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Sample records for human ankle stiffness

  1. Leg stiffness primarily depends on ankle stiffness during human hopping.

    Science.gov (United States)

    Farley, C T; Morgenroth, D C

    1999-03-01

    When humans hop in place or run forward, they adjust leg stiffness to accommodate changes in stride frequency or surface stiffness. The goal of the present study was to determine the mechanisms by which humans adjust leg stiffness during hopping in place. Five subjects hopped in place at 2.2 Hz while we collected force platform and kinematic data. Each subject completed trials in which they hopped to whatever height they chose ("preferred height hopping") and trials in which they hopped as high as possible ("maximum height hopping"). Leg stiffness was approximately twice as great for maximum height hopping as for preferred height hopping. Ankle torsional stiffness was 1.9-times greater while knee torsional stiffness was 1.7-times greater in maximum height hopping than in preferred height hopping. We used a computer simulation to examine the sensitivity of leg stiffness to the observed changes in ankle and knee stiffness. Our model consisted of four segments (foot, shank, thigh, head-arms-trunk) interconnected by three torsional springs (ankle, knee, hip). In the model, increasing ankle stiffness by 1.9-fold, as observed in the subjects, caused leg stiffness to increase by 2.0-fold. Increasing knee stiffness by 1.7-fold had virtually no effect on leg stiffness. Thus, we conclude that the primary mechanism for leg stiffness adjustment is the adjustment of ankle stiffness.

  2. Direct measurement of human ankle stiffness during quiet standing: the intrinsic mechanical stiffness is insufficient for stability.

    Science.gov (United States)

    Loram, Ian D; Lakie, Martin

    2002-12-15

    During quiet standing the human "inverted pendulum" sways irregularly. In previous work where subjects balanced a real inverted pendulum, we investigated what contribution the intrinsic mechanical ankle stiffness makes to achieve stability. Using the results of a plausible model, we suggested that intrinsic ankle stiffness is inadequate for providing stability. Here, using a piezo-electric translator we applied small, unobtrusive mechanical perturbations to the foot while the subject was standing freely. These short duration perturbations had a similar size and velocity to movements which occur naturally during quiet standing, and they produced no evidence of any stretch reflex response in soleus, or gastrocnemius. Direct measurement confirms our earlier conclusion; intrinsic ankle stiffness is not quite sufficient to stabilise the body or pendulum. On average the directly determined intrinsic stiffness is 91 +/- 23 % (mean +/- S.D.) of that necessary to provide minimal stabilisation. The stiffness was substantially constant, increasing only slightly with ankle torque. This stiffness cannot be neurally regulated in quiet standing. Thus we attribute this stiffness to the foot, Achilles' tendon and aponeurosis rather than the activated calf muscle fibres. Our measurements suggest that the triceps surae muscles maintain balance via a spring-like element which is itself too compliant to guarantee stability. The implication is that the brain cannot set ankle stiffness and then ignore the control task because additional modulation of torque is required to maintain balance. We suggest that the triceps surae muscles maintain balance by predictively controlling the proximal offset of the spring-like element in a ballistic-like manner.

  3. Estimation of quasi-stiffness and propulsive work of the human ankle in the stance phase of walking.

    Science.gov (United States)

    Shamaei, Kamran; Sawicki, Gregory S; Dollar, Aaron M

    2013-01-01

    Characterizing the quasi-stiffness and work of lower extremity joints is critical for evaluating human locomotion and designing assistive devices such as prostheses and orthoses intended to emulate the biological behavior of human legs. This work aims to establish statistical models that allow us to predict the ankle quasi-stiffness and net mechanical work for adults walking on level ground. During the stance phase of walking, the ankle joint propels the body through three distinctive phases of nearly constant stiffness known as the quasi-stiffness of each phase. Using a generic equation for the ankle moment obtained through an inverse dynamics analysis, we identify key independent parameters needed to predict ankle quasi-stiffness and propulsive work and also the functional form of each correlation. These parameters include gait speed, ankle excursion, and subject height and weight. Based on the identified form of the correlation and key variables, we applied linear regression on experimental walking data for 216 gait trials across 26 subjects (speeds from 0.75-2.63 m/s) to obtain statistical models of varying complexity. The most general forms of the statistical models include all the key parameters and have an R(2) of 75% to 81% in the prediction of the ankle quasi-stiffnesses and propulsive work. The most specific models include only subject height and weight and could predict the ankle quasi-stiffnesses and work for optimal walking speed with average error of 13% to 30%. We discuss how these models provide a useful framework and foundation for designing subject- and gait-specific prosthetic and exoskeletal devices designed to emulate biological ankle function during level ground walking.

  4. Estimation of quasi-stiffness and propulsive work of the human ankle in the stance phase of walking.

    Directory of Open Access Journals (Sweden)

    Kamran Shamaei

    Full Text Available Characterizing the quasi-stiffness and work of lower extremity joints is critical for evaluating human locomotion and designing assistive devices such as prostheses and orthoses intended to emulate the biological behavior of human legs. This work aims to establish statistical models that allow us to predict the ankle quasi-stiffness and net mechanical work for adults walking on level ground. During the stance phase of walking, the ankle joint propels the body through three distinctive phases of nearly constant stiffness known as the quasi-stiffness of each phase. Using a generic equation for the ankle moment obtained through an inverse dynamics analysis, we identify key independent parameters needed to predict ankle quasi-stiffness and propulsive work and also the functional form of each correlation. These parameters include gait speed, ankle excursion, and subject height and weight. Based on the identified form of the correlation and key variables, we applied linear regression on experimental walking data for 216 gait trials across 26 subjects (speeds from 0.75-2.63 m/s to obtain statistical models of varying complexity. The most general forms of the statistical models include all the key parameters and have an R(2 of 75% to 81% in the prediction of the ankle quasi-stiffnesses and propulsive work. The most specific models include only subject height and weight and could predict the ankle quasi-stiffnesses and work for optimal walking speed with average error of 13% to 30%. We discuss how these models provide a useful framework and foundation for designing subject- and gait-specific prosthetic and exoskeletal devices designed to emulate biological ankle function during level ground walking.

  5. Triceps surae short latency stretch reflexes contribute to ankle stiffness regulation during human running.

    Science.gov (United States)

    Cronin, Neil J; Carty, Christopher P; Barrett, Rod S

    2011-01-01

    During human running, short latency stretch reflexes (SLRs) are elicited in the triceps surae muscles, but the function of these responses is still a matter of controversy. As the SLR is primarily mediated by Ia afferent nerve fibres, various methods have been used to examine SLR function by selectively blocking the Ia pathway in seated, standing and walking paradigms, but stretch reflex function has not been examined in detail during running. The purpose of this study was to examine triceps surae SLR function at different running speeds using Achilles tendon vibration to modify SLR size. Ten healthy participants ran on an instrumented treadmill at speeds between 7 and 15 km/h under 2 Achilles tendon vibration conditions: no vibration and 90 Hz vibration. Surface EMG from the triceps surae and tibialis anterior muscles, and 3D lower limb kinematics and ground reaction forces were simultaneously collected. In response to vibration, the SLR was depressed in the triceps surae muscles at all speeds. This coincided with short-lasting yielding at the ankle joint at speeds between 7 and 12 km/h, suggesting that the SLR contributes to muscle stiffness regulation by minimising ankle yielding during the early contact phase of running. Furthermore, at the fastest speed of 15 km/h, the SLR was still depressed by vibration in all muscles but yielding was no longer evident. This finding suggests that the SLR has greater functional importance at slow to intermediate running speeds than at faster speeds.

  6. Triceps surae short latency stretch reflexes contribute to ankle stiffness regulation during human running.

    Directory of Open Access Journals (Sweden)

    Neil J Cronin

    Full Text Available During human running, short latency stretch reflexes (SLRs are elicited in the triceps surae muscles, but the function of these responses is still a matter of controversy. As the SLR is primarily mediated by Ia afferent nerve fibres, various methods have been used to examine SLR function by selectively blocking the Ia pathway in seated, standing and walking paradigms, but stretch reflex function has not been examined in detail during running. The purpose of this study was to examine triceps surae SLR function at different running speeds using Achilles tendon vibration to modify SLR size. Ten healthy participants ran on an instrumented treadmill at speeds between 7 and 15 km/h under 2 Achilles tendon vibration conditions: no vibration and 90 Hz vibration. Surface EMG from the triceps surae and tibialis anterior muscles, and 3D lower limb kinematics and ground reaction forces were simultaneously collected. In response to vibration, the SLR was depressed in the triceps surae muscles at all speeds. This coincided with short-lasting yielding at the ankle joint at speeds between 7 and 12 km/h, suggesting that the SLR contributes to muscle stiffness regulation by minimising ankle yielding during the early contact phase of running. Furthermore, at the fastest speed of 15 km/h, the SLR was still depressed by vibration in all muscles but yielding was no longer evident. This finding suggests that the SLR has greater functional importance at slow to intermediate running speeds than at faster speeds.

  7. Joint stiffness of the ankle and the knee in running.

    Science.gov (United States)

    Günther, Michael; Blickhan, Reinhard

    2002-11-01

    The spring-mass model is a valid fundament to understand global dynamics of fast legged locomotion under gravity. The underlying concept of elasticity, implying leg stiffness as a crucial parameter, is also found on lower motor control levels, i.e. in muscle-reflex and muscle-tendon systems. Therefore, it seems reasonable that global leg stiffness emerges from local elasticity established by appropriate joint torques. A recently published model of an elastically operating, segmented leg predicts that proper adjustment of joint elasticities to the leg geometry and initial conditions of ground contact provides internal leg stability. Another recent study suggests that in turn the leg segmentation and the initial conditions may be a consequence of metabolic and bone stress constraints. In this study, the theoretical predictions were verified experimentally with respect to initial conditions and elastic joint characteristics in human running. Kinematics and kinetics were measured and the joint torques were estimated by inverse dynamics. Stiffnesses and elastic nonlinearities describing the resulting joint characteristics were extracted from parameter fits. Our results clearly support the theoretical predictions: the knee joint is always stiffer and more extended than the ankle joint. Moreover, the knee torque characteristic on the average shows the higher nonlinearity. According to literature, the leg geometry is a consequence of metabolic and material stress limitations. Adapted to this given geometry, the initial joint angle conditions in fast locomotion are a compromise between metabolic and control effort minimisation. Based on this adaptation, an appropriate joint stiffness ratio between ankle and knee passively safeguards the internal leg stability. The identified joint nonlinearities contribute to the linearisation of the leg spring.

  8. The effects of ankle Kinesio taping on ankle stiffness and dynamic balance.

    Science.gov (United States)

    Fayson, Shirleeah D; Needle, Alan R; Kaminski, Thomas W

    2013-01-01

    The purpose of this study was to determine the effects of Kinesio® taping on static restraint and dynamic postural control of the ankle joint. Thirty female subjects with no history of ankle injury participated in this study. Subjects were tested for passive ankle laxity and stiffness, and time to stabilization following forward, backward, medial, and lateral hops. Subjects were tested prior to tape application, immediately following application, and following 24 hours of use. Differences between taping conditions were investigated using analyses of variance and pairwise comparisons. Stiffness increased following initial application and 24 hours of Kinesio® tape use (F = 6.99, p = .003), despite no observed changes in ankle laxity (F = 0.77, p = .49); however, no changes were observed in time-to-stabilization (F = 0.03, p = .97). Our results suggest that Kinesio® tape may improve static restraint in the ankle joint without altering peak motion or dynamic postural control. A future investigation into Kinesio® tape efficacy in injury prevention or rehabilitation is warranted.

  9. Design of a simple, lightweight, passive-elastic ankle exoskeleton supporting ankle joint stiffness

    Science.gov (United States)

    Kim, Seyoung; Son, Youngsu; Choi, Sangkyu; Ham, Sangyong; Park, Cheolhoon

    2015-09-01

    In this study, a passive-elastic ankle exoskeleton (PEAX) with a one-way clutch mechanism was developed and then pilot-tested with vertical jumping to determine whether the PEAX is sufficiently lightweight and comfortable to be used in further biomechanical studies. The PEAX was designed to supplement the function of the Achilles tendon and ligaments as they passively support the ankle torque with their inherent stiffness. The main frame of the PEAX consists of upper and lower parts connected to each other by tension springs (N = 3) and lubricated hinge joints. The upper part has an offset angle of 5° with respect to the vertical line when the springs are in their resting state. Each spring has a slack length of 8 cm and connects the upper part to the tailrod of the lower part in the neutral position. The tailrod freely rotates with low friction but has a limited range of motion due to the stop pin working as a one-way clutch. Because of the one-way clutch system, the tension springs store the elastic energy only due to an ankle dorsiflexion when triggered by the stop pin. This clutch mechanism also has the advantage of preventing any inconvenience during ankle plantarflexion because it does not limit the ankle joint motion during the plantarflexion phase. In pilot jumping tests, all of the subjects reported that the PEAX was comfortable for jumping due to its lightweight (approximately 1 kg) and compact (firmly integrated with shoes) design, and subjects were able to nearly reach their maximum vertical jump heights while wearing the PEAX. During the countermovement jump, elastic energy was stored during dorsiflexion by spring extension and released during plantarflexion by spring restoration, indicating that the passive spring torque (i.e., supportive torque) generated by the ankle exoskeleton partially supported the ankle joint torque throughout the process.

  10. Summary of Human Ankle Mechanical Impedance During Walking

    Science.gov (United States)

    Rouse, Elliott J.; Krebs, Hermano Igo

    2016-01-01

    The human ankle joint plays a critical role during walking and understanding the biomechanical factors that govern ankle behavior and provides fundamental insight into normal and pathologically altered gait. Previous researchers have comprehensively studied ankle joint kinetics and kinematics during many biomechanical tasks, including locomotion; however, only recently have researchers been able to quantify how the mechanical impedance of the ankle varies during walking. The mechanical impedance describes the dynamic relationship between the joint position and the joint torque during perturbation, and is often represented in terms of stiffness, damping, and inertia. The purpose of this short communication is to unify the results of the first two studies measuring ankle mechanical impedance in the sagittal plane during walking, where each study investigated differing regions of the gait cycle. Rouse et al. measured ankle impedance from late loading response to terminal stance, where Lee et al. quantified ankle impedance from pre-swing to early loading response. While stiffness component of impedance increases significantly as the stance phase of walking progressed, the change in damping during the gait cycle is much less than the changes observed in stiffness. In addition, both stiffness and damping remained low during the swing phase of walking. Future work will focus on quantifying impedance during the “push off” region of stance phase, as well as measurement of these properties in the coronal plane. PMID:27766187

  11. Lower limb joint kinetics and ankle joint stiffness in the sprint start push-off.

    Science.gov (United States)

    Charalambous, Laura; Irwin, Gareth; Bezodis, Ian N; Kerwin, David

    2012-01-01

    Sprint push-off technique is fundamental to sprint performance and joint stiffness has been identified as a performance-related variable during dynamic movements. However, joint stiffness for the push-off and its relationship with performance (times and velocities) has not been reported. The aim of this study was to quantify and explain lower limb net joint moments and mechanical powers, and ankle stiffness during the first stance phase of the push-off. One elite sprinter performed 10 maximal sprint starts. An automatic motion analysis system (CODA, 200 Hz) with synchronized force plates (Kistler, 1000 Hz) collected kinematic profiles at the hip, knee, and ankle and ground reaction forces, providing input for inverse dynamics analyses. The lower-limb joints predominately extended and revealed a proximal-to-distal sequential pattern of maximal extensor angular velocity and positive power production. Pearson correlations revealed relationships (P < 0.05) between ankle stiffness (5.93 ± 0.75 N x m x deg(-1)) and selected performance variables. Relationships between negative power phase ankle stiffness and horizontal (r = -0.79) and vertical (r = 0.74) centre of mass velocities were opposite in direction to the positive power phase ankle stiffness (horizontal: r = 0.85; vertical: r = -0.54). Thus ankle stiffness may affect the goals of the sprint push-off in different ways, depending on the phase of stance considered.

  12. Biomechanics of uphill walking using custom ankle-foot orthoses of three different stiffnesses.

    Science.gov (United States)

    Haight, Derek J; Russell Esposito, Elizabeth; Wilken, Jason M

    2015-03-01

    Ankle-foot orthoses (AFOs) can provide support and improve walking ability in individuals with plantarflexor weakness. Passive-dynamic AFO stiffness can be optimized for over-ground walking, however little research exists for uphill walking, when plantarflexor contributions are key. Compare uphill walking biomechanics (1) between dynamic AFO users and able-bodied control subjects. (2) between injured and sound limbs (3) across different AFO stiffnesses. Twelve patients with unilateral limb-salvage and twelve matched, able-bodied controls underwent biomechanical gait analysis when walking up a 10° incline. Three AFO stiffnesses were tested in the patient group: Nominal (clinically prescribed), Compliant (20% less stiff), and Stiff (20% more stiff). AFO users experienced less ankle motion and power generation, lower knee extensor moments, and greater hip flexion and power generation than controls during uphill walking. Despite these deviations, they walked at equivalent self-selected velocities and stride lengths. Asymmetries were present at the ankle and knee with decreased ankle motion and power, and lower knee extensor moments on the AFO limb. Stiffer AFOs increased knee joint flexion but a 40% range in AFO stiffness had few other effects on gait. Therefore, a wide range of clinically prescribed AFO stiffnesses may adequately assist uphill walking. Published by Elsevier B.V.

  13. Time-varying identification of ankle dynamic joint stiffness during movement with constant muscle activation.

    Science.gov (United States)

    Guarin, Diego L; Kearney, Robert E

    2015-01-01

    Dynamic joint stiffness defines the torque generated at the joint in response to position perturbations. Dynamic stiffness is modulated by the angular position and the muscle activation level, making it difficult to estimate during large movements and/or time-varying muscle contractions. This paper presents a new methodology for estimating dynamic joint stiffness during movement and muscle activation. For this, we formulate a novel, nonlinear, dynamic joint stiffness model and present a new algorithm to estimate its parameters. The algorithm assumes that the variability in the model parameters is a function of the mean joint position. Using this methodology we estimated the dynamic joint stiffness at the ankle throughout ramp and hold displacements during a constant muscle contraction. The estimated model accurately predicted the intrinsic and reflex torques produced at the ankle as a response to small position perturbations during large displacement with muscle activation. Preliminary results show that during muscle contraction, ankle intrinsic stiffness estimated during movement is significantly lower than that estimated during quasi-stationary experiments.

  14. A Comparison of Total and Intrinsic Muscle Stiffness Among Flexors and Extensors of the Ankle, Knee and Elbow

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    Lemoine, Sandra M.

    1997-01-01

    This study examined 3 methods that assessed muscle stiffness. Muscle stiffness has been quantified by tissue reactive force (transverse stiffness), vibration, and force (or torque) over displacement. Muscle stiffness also has two components: reflex (due to muscle sensor activity) and intrinsic (tonic firing of motor units, elastic nature of actin and myosin cross bridges, and connective tissue). This study compared three methods of measuring muscle stiffness of agonist-antagonist muscle pairs of the ankle, knee and elbow.

  15. Effects of plyometric training on passive stiffness of gastrocnemii and the musculo-articular complex of the ankle joint.

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    Fouré, A; Nordez, A; Guette, M; Cornu, C

    2009-12-01

    This study aimed to determine simultaneously the effects of plyometric training on the passive stiffness of the ankle joint musculo-articular complex, the gastrocnemii muscle-tendon complex (MTC) and the Achilles tendon in order to assess possible local adaptations of elastic properties. Seventeen subjects were divided into a trained (TG) group and a control (CG) group. They were tested before and after 8 weeks of a plyometric training period. The ankle joint range of motion (RoM), the global musculo-articular passive stiffness of the ankle joint, the maximal passive stiffness of gastrocnemii and the stiffness of the Achilles tendon during isometric plantar flexion were determined. A significant increase in the jump performances of TG relative to CG was found (squat jumps: +17.6%, P=0.008; reactive jumps: +19.8%, P=0.001). No significant effect of plyometric training was observed in the ankle joint RoM, musculo-articular passive stiffness of the ankle joint or Achilles tendon stiffness (P>0.05). In contrast, the maximal passive stiffness of gastrocnemii of TG increased after plyometric training relative to CG (+33.3%, P=0.001). Thus, a specific adaptation of the gastrocnemii MTC occurred after plyometric training, without affecting the global passive musculo-articular stiffness of the ankle joint.

  16. The contribution of quasi-joint stiffness of the ankle joint to gait in patients with hemiparesis.

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    Sekiguchi, Yusuke; Muraki, Takayuki; Kuramatsu, Yuko; Furusawa, Yoshihito; Izumi, Shin-Ichi

    2012-06-01

    The role of ankle joint stiffness during gait in patients with hemiparesis has not been clarified. The purpose of this study was to determine the contribution of quasi-joint stiffness of the ankle joint to spatiotemporal and kinetic parameters regarding gait in patients with hemiparesis due to brain tumor or stroke and healthy individuals. Spatiotemporal and kinetic parameters regarding gait in twelve patients with hemiparesis due to brain tumor or stroke and nine healthy individuals were measured with a 3-dimensional motion analysis system. Quasi-joint stiffness was calculated from the slope of the linear regression of the moment-angle curve of the ankle joint during the second rocker. There was no significant difference in quasi-joint stiffness among both sides of patients and the right side of controls. Quasi-joint stiffness on the paretic side of patients with hemiparesis positively correlated with maximal ankle power (r=0.73, Phemiparesis. In contrast, healthy individuals might decrease quasi-joint stiffness to avoid deceleration of forward tilt of the tibia. Our findings might be useful for selecting treatment for increased ankle stiffness due to contracture and spasticity in patients with hemiparesis. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Predictive simulation of diabetic gait: Individual contribution of ankle stiffness and muscle weakening.

    Science.gov (United States)

    Santos, Gilmar F; Gomes, Aline A; Sacco, Isabel C N; Ackermann, Marko

    2017-08-01

    Diabetic neuropathic individuals present massive muscle strength reduction at the ankle plantar- and dorsiflexors and increased joint stiffness. Our aim is to investigate the adaptation strategies to these musculoskeletal alterations during walking by means of predictive simulations. We used a seven segment planar musculoskeletal model actuated by eight Hill-type muscles in each leg. The effect of all passive tissue in muscles and other joint structures was modeled by net passive joint moment curves. The predictive simulations were generated by solving an optimal control problem that minimized a cost function, including effort and tracking terms, using direct collocation and a commercial optimal control package. We simulate four conditions to represent the weakening of the distal muscles triceps sural (TS) and tibialis anterior (TA), and five conditions to represent the effect of increasing nonlinear ankle stiffness in flexion. The weakening of the distal muscles leads to a delayed action of the TS and a progressive decrease of the gastrocnemius peak force in the push-off phase. This distal deficit is compensated by a larger hip flexion moment resulting from an increase in the iliopsoas muscle force in this phase, known as the hip strategy. The adaptation mechanisms observed in response to an increase in ankle stiffness include the hip strategy and the exploitation of the passive joint structures as springs, which store energy during midstance and release it during push-off, reducing TS force and power in this phase and leading to a consistent decrease in the overall muscle force levels. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Voluntary control of human jaw stiffness.

    Science.gov (United States)

    Shiller, Douglas M; Houle, Guillaume; Ostry, David J

    2005-09-01

    Recent studies of human arm movement have suggested that the control of stiffness may be important both for maintaining stability and for achieving differences in movement accuracy. In the present study, we have examined the voluntary control of postural stiffness in 3D in the human jaw. The goal is to address the possible role of stiffness control in both stabilizing the jaw and in achieving the differential precision requirements of speech sounds. We previously showed that patterns of kinematic variability in speech are systematically related to the stiffness of the jaw. If the nervous system uses stiffness control as a means to regulate kinematic variation in speech, it should also be possible to show that subjects can voluntarily modify jaw stiffness. Using a robotic device, a series of force pulses was applied to the jaw to elicit changes in stiffness to resist displacement. Three orthogonal directions and three magnitudes of forces were tested. In all conditions, subjects increased the magnitude of jaw stiffness to resist the effects of the applied forces. Apart from the horizontal direction, greater increases in stiffness were observed when larger forces were applied. Moreover, subjects differentially increased jaw stiffness along a vertical axis to counteract disturbances in this direction. The observed changes in the magnitude of stiffness in different directions suggest an ability to control the pattern of stiffness of the jaw. The results are interpreted as evidence that jaw stiffness can be adjusted voluntarily, and thus may play a role in stabilizing the jaw and in controlling movement variation in the orofacial system.

  19. Distinguishing active from passive components of ankle plantar flexor stiffness in stroke, spinal cord injury and multiple sclerosis

    DEFF Research Database (Denmark)

    Lorentzen, Jakob; Grey, Michael J; Crone, Clarissa

    2010-01-01

    to distinguish the contribution of active reflex mechanisms from passive muscle properties to ankle joint stiffness in 31 healthy, 10 stroke, 30 multiple sclerosis and 16 spinal cord injured participants. The results were compared to routine clinical evaluation of spasticity. METHODS: A computer......, but it did not reach statistical significance, except in the stroke group (p

  20. Human plantarflexor stiffness to multiple single-stretch trials.

    Science.gov (United States)

    Blanpied, P; Smidt, G L

    1992-01-01

    The purpose of this investigation was to determine the influence of different stretch velocities, different rates of pre-stretch force development, and different pre-stretch muscle lengths on the intrinsic stiffness exhibited by the quasi-statically contracting active human plantarflexors during multiple single-stretch trials at 20-60% of maximum isometric contraction. Subjects were positioned prone, with the knee flexed 1.57 rad(90 degrees), shank stabilized, and foot secured in a hard plastic orthotic. Slowly increasing isometric plantarflexion force was produced until the plantarflexors were stretched by a rapid 0.2 rad (12 degrees) dorsiflexion movement. Plantarflexion forces and ankle positions were determined during these stretches as well as during resting stretches when the muscle was inactive. Resting forces were subtracted from the active trials, forces converted to torques, and stiffnesses determined for the first 62 ms of the stretch. The slope of the stiffness vs pre-stretch torque relationship averaged 4.30 +/- 0.34 Nm rad-1 Nm-1. Little difference was found between stiffness determined through the single-stretch method and the results of previous studies employing different mechanical inputs. Differences in stiffnesses with different stretching velocities were caused by computational artifact rather than by differences in intrinsic muscular reaction. Faster rates of pre-stretch force increase prior to the stretch resulted in slightly lower stiffnesses. Different pre-stretch muscle lengths apparently did not result in different stiffnesses. The shape of the torque vs displacement curve was remarkably insensitive to the planned manipulations of the testing conditions, responding in a stereotypical manner.

  1. Arterial stiffness evaluation by cardio-ankle vascular index in hypertension and diabetes mellitus subjects.

    Science.gov (United States)

    Wang, Hongyu; Liu, Jinbo; Zhao, Hongwei; Fu, Xiaobao; Shang, Guangyun; Zhou, Yingyan; Yu, Xiaolan; Zhao, Xujing; Wang, Guang; Shi, Hongyan

    2013-01-01

    Arterial stiffness is an independent predictor for vascular diseases. Cardio-ankle vascular index (CAVI) is a new index of arterial stiffness. In the present study, we investigated the possible risk factors involving CAVI in hypertension and diabetes mellitus (DM) subjects. One thousand sixty-three subjects (M/F 533/530) from Shougang Corporation Examination Center were divided into four groups: healthy group (n = 639); hypertension group (n = 312); DM group (n = 58); and hypertension with DM group (n = 54). CAVI was measured by VS-1000 apparatus. Our results showed that CAVI was significantly higher in hypertension subjects with DM than in healthy and hypertension group, respectively (8.59 ± 1.08 vs 7.23 ± 1.10; 8.59 ± 1.08 vs 7.94 ± 1.33; both P hypertension subjects with DM compared with healthy and hypertension groups. Copyright © 2013 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

  2. Resveratrol Ameliorates Arterial Stiffness Assessed by Cardio-Ankle Vascular Index in Patients With Type 2 Diabetes Mellitus.

    Science.gov (United States)

    Imamura, Haruki; Yamaguchi, Takashi; Nagayama, Daiji; Saiki, Atsuhito; Shirai, Kohji; Tatsuno, Ichiro

    2017-08-03

    Resveratrol has been reported to have potent anti-atherosclerotic effects in animal studies. However, there are few interventional studies in human patients with atherosclerogenic diseases. The cardio-ankle vascular index (CAVI) reflects arterial stiffness and is a clinical surrogate marker of atherosclerosis. The aim of the present study was to investigate the effect of resveratrol on arterial stiffness assessed by CAVI in patients with type 2 diabetes mellitus (T2DM).In this double-blind, randomized, placebo-controlled study, 50 patients with T2DM received supplement of a 100mg resveratrol tablet (total resveratrol: oligo-stilbene 27.97 mg/100 mg/day) or placebo daily for 12 weeks. CAVI was assessed at baseline and the end of study. Body weight (BW), blood pressure (BP), glucose and lipid metabolic parameters, and diacron-reactive oxygen metabolites (d-ROMs; an oxidative stress marker) were also measured.Resveratrol supplementation decreased systolic BP (-5.5 ± 13.0 mmHg), d-ROMs (-25.6 ± 41.8 U.CARR), and CAVI (-0.4 ± 0.7) significantly (P resveratrol group than in the placebo group. Multivariate logistic regression analysis identified resveratrol supplementation as an independent predictor for a CAVI decrease of more than 0.5.In conclusion, 12-week resveratrol supplementation may improve arterial stiffness and reduce oxidative stress in patients with T2DM. Resveratrol may be beneficial in preventing the development of atherosclerosis induced by diabetes. However, a large-scale cohort study is required to validate the present findings.

  3. Influence of musculo-tendinous stiffness of the plantar ankle flexor muscles upon maximal power output on a cycle ergometre.

    Science.gov (United States)

    Driss, Tarak; Lambertz, Daniel; Rouis, Majdi; Vandewalle, Henry

    2012-11-01

    The importance of maximal voluntary torque (T (MVC)), maximal rate of torque development (MRTD) and musculo-tendinous stiffness of the triceps surae for maximal power output on a cycle ergometre (Pmax) was studied in 21 healthy subjects by studying the relationships between maximal cycling power related to body mass (Pmax BM(-1)) with T (MVC), MRTD and different indices of musculo-tendinous stiffness of the ankle flexor. Pmax BM(-1) was calculated from the data of an all-out force-velocity test on a Monark cycle ergometre. T (MVC) and MRTD were measured on a specific ankle ergometre. Musculo-tendinous stiffness was estimated by means of quick releases at 20, 40, 60 and 80% T (MVC) on the same ankle ergometre. Pmax BM(-1) was significantly and positively correlated with MRTD related to body mass but the positive correlation between Pmax BM(-1) and T (MVC) did not reach the significance level (0.05). Pmax BM(-1) was significantly and positively correlated with the estimation of stiffness at 40% T (MVC) (S(0.4)), but not with stiffness at 20, 60 and 80% T (MVC). The results of the present study suggest that maximal power output during cycling is significantly correlated with the level of musculo-tendinous stiffness which corresponds to torque range around peak torque at optimal pedal rate. However, the low coefficient of determination (r2 = 0.203) between Pmax BM(-1) and S (0.4) BM(-1) suggested that Pmax BM(-1) largely depended on other factors than the musculo-tendinous stiffness of the only plantar flexors.

  4. Determination of ankle external fixation stiffness by expedited interactive finite element analysis.

    Science.gov (United States)

    Nielsen, Jonathan K; Saltzman, Charles L; Brown, Thomas D

    2005-11-01

    Interactive finite element analysis holds the potential to quickly and accurately determine the mechanical stiffness of alternative external fixator frame configurations. Using as an example Ilizarov distraction of the ankle, a finite element model and graphical user interface were developed that provided rapid, construct-specific information on fixation rigidity. After input of specific construct variables, the finite element software determined the resulting tibial displacement for a given configuration in typically 15s. The formulation was employed to investigate constructs used to treat end-stage arthritis, both in a parametric series and for five specific clinical distraction cases. Parametric testing of 15 individual variables revealed that tibial half-pins were much more effective than transfixion wires in limiting axial tibial displacement. Factors most strongly contributing to stiffening the construct included placing the tibia closer to the fixator rings, and mounting the pins to the rings at the nearest circumferential location to the bone. Benchtop mechanical validation results differed inappreciably from the finite element computations.

  5. The effect of ankle foot orthosis stiffness on the energy cost of walking: A simulation study

    NARCIS (Netherlands)

    Bregman, D.J.J.; Van der Krogt, M.M.; De Groot, V.; Harlaar, J.; Wisse, M.; Collins, S.H.

    2011-01-01

    Background In stroke and multiple sclerosis patients, gait is frequently hampered by a reduced ability to push-off with the ankle caused by weakness of the plantar-flexor muscles. To enhance ankle push-off and to decrease the high energy cost of walking, spring-like carbon-composite Ankle Foot Ortho

  6. Mechanically induced ankle inversion during human walking and jumping.

    NARCIS (Netherlands)

    Nieuwenhuijzen, P.H.J.A.; Grüneberg, C.; Duysens, J.E.J.

    2002-01-01

    A new method to study sudden ankle inversions during human walking and jumping is presented. Ankle inversions of 25 degrees were elicited using a box containing a trap door. During the gait task, subjects walked at a speed of 4 km/h. At a pre-programmed delay after left heel strike, an electromagnet

  7. Mechanically induced ankle inversion during human walking and jumping.

    NARCIS (Netherlands)

    Nieuwenhuijzen, P.H.J.A.; Grüneberg, C.; Duysens, J.E.J.

    2002-01-01

    A new method to study sudden ankle inversions during human walking and jumping is presented. Ankle inversions of 25 degrees were elicited using a box containing a trap door. During the gait task, subjects walked at a speed of 4 km/h. At a pre-programmed delay after left heel strike, an electromagnet

  8. Recycling Energy to Restore Impaired Ankle Function during Human Walking

    NARCIS (Netherlands)

    Collins, S.H.; Kuo, A.D.

    2010-01-01

    Background: Humans normally dissipate significant energy during walking, largely at the transitions between steps. The ankle then acts to restore energy during push-off, which may be the reason that ankle impairment nearly always leads to poorer walking economy. The replacement of lost energy is nec

  9. To evaluate the efficacy of Mobilization Techniques in Post-Traumatic stiff ankle with and without Paraffin Wax Bath.

    Science.gov (United States)

    Rashid, Sajid; Salick, Kamran; Kashif, Muhammah; Ahmad, Awad; Sarwar, Kashif

    2013-11-01

    Mobilization techniques are frequently used by physiotherapists to reduce pain, improve joint movement and facilitate return to activities after injury. The objective of this study was to explore differences in the efficacy of Mobilization Techniques in Post-Traumatic stiff ankle with and without Paraffin Wax Bath. Thirty seven patients of Post Traumatic stiff ankle were recruited for the study at Sajid Physiotherapy & Rehabilitation center, Multan from March 2011 to February 2013. It was a randomized controlled trial and the patients with equal grades of severity were placed in control and study groups. Group A had nineteen patients and Group B had 18 patients. The inclusion criteria were age range from 20-60 years, pain, loss of ROM, with history of trauma and fracture of ankle. The patients with similar complaints but with surgical treatment were excluded. Group A was given mobilization techniques with paraffin wax bath while group B was treated without paraffin wax bath. Improvement was observed by EscolaPaulista de Medicina Range of Motion (EPM-ROM) scale and visual analogue scale (VAS). After ten weeks of treatment, the patients were re-evaluated by an orthopedic surgeon and a Physiotherapist for their symptoms and ROM. t-test was applied to compare outcome between two groups and p movement showed improvement in inversion in group A (0.875 ± 0.276) vs. group B (0.966 ± 0.305) and in eversion in group A (0.948 ± 0.300) vs. group B (0.674 ± 0.213). Mobilization Techniques followed by wax bath resulted in significant improvements of range of motion (ROM), clinical and functional changes. Wax bath alone had no significant effect. After ten weeks intervention treatment, t-test was applied to compare outcome between the two groups and p=0.001to 0.004 in group A and p= 0.104 to 0.168 in group B, (pmobilization and wax bath therapy is an effective and beneficial tool to improve the symptoms and quality of life in post traumatic stiff ankle patients. Joint

  10. Recycling energy to restore impaired ankle function during human walking.

    Directory of Open Access Journals (Sweden)

    Steven H Collins

    Full Text Available BACKGROUND: Humans normally dissipate significant energy during walking, largely at the transitions between steps. The ankle then acts to restore energy during push-off, which may be the reason that ankle impairment nearly always leads to poorer walking economy. The replacement of lost energy is necessary for steady gait, in which mechanical energy is constant on average, external dissipation is negligible, and no net work is performed over a stride. However, dissipation and replacement by muscles might not be necessary if energy were instead captured and reused by an assistive device. METHODOLOGY/PRINCIPAL FINDINGS: We developed a microprocessor-controlled artificial foot that captures some of the energy that is normally dissipated by the leg and "recycles" it as positive ankle work. In tests on subjects walking with an artificially-impaired ankle, a conventional prosthesis reduced ankle push-off work and increased net metabolic energy expenditure by 23% compared to normal walking. Energy recycling restored ankle push-off to normal and reduced the net metabolic energy penalty to 14%. CONCLUSIONS/SIGNIFICANCE: These results suggest that reduced ankle push-off contributes to the increased metabolic energy expenditure accompanying ankle impairments, and demonstrate that energy recycling can be used to reduce such cost.

  11. Adding Stiffness to the Foot Modulates Soleus Force-Velocity Behaviour during Human Walking

    Science.gov (United States)

    Takahashi, Kota Z.; Gross, Michael T.; van Werkhoven, Herman; Piazza, Stephen J.; Sawicki, Gregory S.

    2016-07-01

    Previous studies of human locomotion indicate that foot and ankle structures can interact in complex ways. The structure of the foot defines the input and output lever arms that influences the force-generating capacity of the ankle plantar flexors during push-off. At the same time, deformation of the foot may dissipate some of the mechanical energy generated by the plantar flexors during push-off. We investigated this foot-ankle interplay during walking by adding stiffness to the foot through shoes and insoles, and characterized the resulting changes in in vivo soleus muscle-tendon mechanics using ultrasonography. Added stiffness decreased energy dissipation at the foot (p muscle lever arms) (p muscle behaviour, leading to greater peak force (p shortening speed (p < 0.001). Despite this shift in force-velocity behaviour, the whole-body metabolic cost during walking increased with added foot stiffness (p < 0.001). This increased metabolic cost is likely due to the added force demand on the plantar flexors, as walking on a more rigid foot/shoe surface compromises the plantar flexors’ mechanical advantage.

  12. A Novel Design for Adjustable Stiffness Artificial Tendon for the Ankle Joint of a Bipedal Robot: Modeling & Simulation

    Directory of Open Access Journals (Sweden)

    Aiman Omer

    2015-12-01

    Full Text Available Bipedal humanoid robots are expected to play a major role in the future. Performing bipedal locomotion requires high energy due to the high torque that needs to be provided by its legs’ joints. Taking the WABIAN-2R as an example, it uses harmonic gears in its joint to increase the torque. However, using such a mechanism increases the weight of the legs and therefore increases energy consumption. Therefore, the idea of developing a mechanism with adjustable stiffness to be connected to the leg joint is introduced here. The proposed mechanism would have the ability to provide passive and active motion. The mechanism would be attached to the ankle pitch joint as an artificial tendon. Using computer simulations, the dynamical performance of the mechanism is analytically evaluated.

  13. Differentiation between non-neural and neural contributors to ankle joint stiffness in cerebral palsy

    NARCIS (Netherlands)

    De Gooijer-van de Groep, K.L.; De Vlugt, E.; De Groot, J.H.; Van der Heijden-Maessen, H.C.M.; Wielheesen, D.H.M.; Van Wijlen-Hempel, R.M.S.; Arendzen, J.H.; Meskers, C.G.M.

    2013-01-01

    Background Spastic paresis in cerebral palsy (CP) is characterized by increased joint stiffness that may be of neural origin, i.e. improper muscle activation caused by e.g. hyperreflexia or non-neural origin, i.e. altered tissue viscoelastic properties (clinically: “spasticity” vs. “contracture”). D

  14. A controlled-release ergometer for the human ankle

    NARCIS (Netherlands)

    Hof, AL

    1997-01-01

    A hydraulic ergometer for the human foot is described that can apply ankle rotations up to 1 rad at a constant high speed of 10-20 rad/s against moments up to 200 N m. The initial acceleration is damped, so as not to exceed a preset value. With the presented set-up the series elasticity of the intac

  15. Gait training reduces ankle joint stiffness and facilitates heel strike in children with Cerebral Palsy

    DEFF Research Database (Denmark)

    Willerslev-Olsen, Maria; Lorentzen, Jakob; Nielsen, Jens Bo

    2014-01-01

    stretches below and above reflex threshold. Gait kinematics were recorded by 3-D video-analysis during treadmill walking. Foot pressure was measured by force-sensitive foot soles during treadmill and over-ground walking. RESULTS: Children with increased passive stiffness showed a significant reduction...... and facilitate toe lift and heel strike in children with CP. Intensive gait training may be beneficial in preventing contractures and maintain gait ability in children with CP....

  16. How Does Ankle-foot Orthosis Stiffness Affect Gait in Patients With Lower Limb Salvage?

    Science.gov (United States)

    2014-05-10

    tested and between the patient and control groups. Results An increase in AFO compliance resulted in 20% to 26% less knee flexion relative to the...was calculated from the forward progression of a marker on the seventh cervical vertebrae and corresponded to a dimensionless Froude number of 0.16...in a 20% decrease in stance phase knee flexion relative to the nominal strut (p = 0.003) and a 26% decrease relative to the stiff strut (p = 0.001

  17. Contribution of the transverse arch to foot stiffness in humans

    OpenAIRE

    Yawar, Ali; Korpas, Lucia; Lugo-Bolanos, Maria; Mandre, Shreyas; Venkadesan, Madhusudhan

    2017-01-01

    Stiffness of the human foot is central to its mechanical function, such as elastic energy storage and propulsion. Its doubly-arched structure, manifested as longitudinal and transverse arches, is thought to underlie the stiff nature. However, previous studies have focused solely on the longitudinal arch, and little is known about whether and how the transverse arch impacts the foot's stiffness. The common observation that a flexible currency bill significantly stiffens upon curling it transve...

  18. Assessment of a portable device for the quantitative measurement of ankle joint stiffness in spastic individuals

    DEFF Research Database (Denmark)

    Lorentzen, Jakob; Grey, Michael J; Geertsen, Svend Sparre

    2012-01-01

    OBJECTIVE: Spasticity is a common complication with neurological diseases and CNS lesions. Instrumented systems to evaluate spasticity often cannot provide an immediate result, thus limiting their clinical usefulness. In this study we investigated the accuracy and reliability of the portable...... was measured with the portable device and a stationary torque motor. Inter- and intra-rater reliability was assessed with the intra-class correlation coefficient (ICC). RESULTS: Stiffness measures with the portable and stationary devices were significantly correlated for controls and MS participants (p...

  19. Total ankle joint replacement.

    Science.gov (United States)

    2016-02-01

    Ankle arthritis results in a stiff and painful ankle and can be a major cause of disability. For people with end-stage ankle arthritis, arthrodesis (ankle fusion) is effective at reducing pain in the shorter term, but results in a fixed joint, and over time the loss of mobility places stress on other joints in the foot that may lead to arthritis, pain and dysfunction. Another option is to perform a total ankle joint replacement, with the aim of giving the patient a mobile and pain-free ankle. In this article we review the efficacy of this procedure, including how it compares to ankle arthrodesis, and consider the indications and complications.

  20. Treadmill training with an incline reduces ankle joint stiffness and improves active range of movement during gait in adults with cerebral palsy

    DEFF Research Database (Denmark)

    Lorentzen, Jakob; Kirk, Henrik; Fernandez-Lago, Helena;

    2016-01-01

    of gait were obtained before and after the intervention/control period. Intervention subjects trained 31.4 SD 10.1 days for 29.0 SD 2.3 min (total) 15.2 h. RESULTS: Passive ankle joint stiffness was reduced (F = 5.1; p = 0.031), maximal gait speed increased (F = 42.8, p ... with contractures. 6 weeks of daily uphill gait training improves functional gait parameters such as gait speed and dorsal flexion during gait in adults with cerebral palsy....

  1. Relationship between resistant hypertension and arterial stiffness assessed by brachial-ankle pulse wave velocity in the older patient

    Directory of Open Access Journals (Sweden)

    Chung CM

    2014-09-01

    Full Text Available Chang-Min Chung,1,2 Hui-Wen Cheng,2 Jung-Jung Chang,2 Yu-Sheng Lin,2 Ju-Feng Hsiao,2 Shih-Tai Chang,1 Jen-Te Hsu2,31School of Traditional Chinese Medicine, College of Medicine, Chang Gung University, 2Division of Cardiology, Chang Gung Memorial Hospital, Chiayi, 3Department of Medicine, College of Medicine, Chang Gung University, Taoyuan County, TaiwanBackground: Resistant hypertension (RH is a common clinical condition associated with increased cardiovascular mortality and morbidity in older patients. Several factors and conditions interfering with blood pressure (BP control, such as excess sodium intake, obesity, diabetes, older age, kidney disease, and certain identifiable causes of hypertension are common in patients resistant to antihypertensive treatment. Arterial stiffness, measured by brachial-ankle pulse wave velocity (baPWV, is increasingly recognized as an important prognostic index and potential therapeutic target in hypertensive patients. The aim of this study was to determine whether there is an association between RH and arterial stiffness. Methods: This study included 1,620 patients aged ≥65 years who were referred or self-referred to the outpatient hypertension unit located at a single cardiovascular center. They were separated into normotensive, controlled BP, and resistant hypertension groups. Home BP, blood laboratory parameters, echocardiographic studies and baPWV all were measured. Results: The likelihood of diabetes mellitus was significantly greater in the RH group than in the group with controlled BP (odds ratio 2.114, 95% confidence interval [CI] 1.194–3.744, P=0.010. Systolic BP was correlated in the RH group significantly more than in the group with controlled BP (odds ratio 1.032, 95% CI 1.012–1.053, P=0.001. baPWV (odds ratio 1.084, 95% CI 1.016–1.156, P=0.015 was significantly correlated with the presence of RH. The other factors were negatively correlated with the existence of RH.Conclusion: In

  2. Leg stiffness and stride frequency in human running.

    Science.gov (United States)

    Farley, C T; González, O

    1996-02-01

    When humans and other mammals run, the body's complex system of muscle, tendon and ligament springs behaves like a single linear spring ('leg spring'). A simple spring-mass model, consisting of a single linear leg spring and a mass equivalent to the animal's mass, has been shown to describe the mechanics of running remarkably well. Force platform measurements from running animals, including humans, have shown that the stiffness of the leg spring remains nearly the same at all speeds and that the spring-mass system is adjusted for higher speeds by increasing the angle swept by the leg spring. The goal of the present study is to determine the relative importance of changes to the leg spring stiffness and the angle swept by the leg spring when humans alter their stride frequency at a given running speed. Human subjects ran on treadmill-mounted force platform at 2.5ms-1 while using a range of stride frequencies from 26% below to 36% above the preferred stride frequency. Force platform measurements revealed that the stiffness of the leg spring increased by 2.3-fold from 7.0 to 16.3 kNm-1 between the lowest and highest stride frequencies. The angle swept by the leg spring decreased at higher stride frequencies, partially offsetting the effect of the increased leg spring stiffness on the mechanical behavior of the spring-mass system. We conclude that the most important adjustment to the body's spring system to accommodate higher stride frequencies is that leg spring becomes stiffer.

  3. Relationship between activation of ankle muscles and quasi-joint stiffness in early and middle stances during gait in patients with hemiparesis.

    Science.gov (United States)

    Sekiguchi, Yusuke; Muraki, Takayuki; Tanaka, Naofumi; Izumi, Shin-Ichi

    2015-09-01

    It is unclear whether muscle contraction is necessary to increase quasi-joint stiffness (QJS) of the ankle joint during gait in patients with hemiparesis. The purpose of the present study was to investigate the relationship between QJS and muscle activation at the ankle joint in the stance phase during gait in patients with hemiparesis. Spatiotemporal and kinetic gait parameters and activation of the medial head of the gastrocnemius (MG), soleus (SOL), and tibialis anterior (TA) muscles were measured using a 3-dimensional motion analysis system and surface electromyography, in 21 patients with hemiparesis due to stroke and 10 healthy individuals. In the early stance, the QJS on the paretic side (PS) of patients was greater than that on the non-PS (phemiparesis, plantarflexor activation may not contribute to QJS in the early stance. On the other hand, QJS in the middle stance may be attributed to activation of the MG and SOL. Our findings suggest that activation of the MG and SOL in the middle stance on the PS may require to be enhanced to increase QJS during gait in patients with hemiparesis. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. The Effects of Varying Ankle Foot Orthosis Stiffness on Gait in Children with Spastic Cerebral Palsy Who Walk with Excessive Knee Flexion.

    Directory of Open Access Journals (Sweden)

    Yvette L Kerkum

    Full Text Available Rigid Ankle-Foot Orthoses (AFOs are commonly prescribed to counteract excessive knee flexion during the stance phase of gait in children with cerebral palsy (CP. While rigid AFOs may normalize knee kinematics and kinetics effectively, it has the disadvantage of impeding push-off power. A spring-like AFO may enhance push-off power, which may come at the cost of reducing the knee flexion less effectively. Optimizing this trade-off between enhancing push-off power and normalizing knee flexion in stance is expected to maximize gait efficiency. This study investigated the effects of varying AFO stiffness on gait biomechanics and efficiency in children with CP who walk with excessive knee flexion in stance. Fifteen children with spastic CP (11 boys, 10±2 years were prescribed with a ventral shell spring-hinged AFO (vAFO. The hinge was set into a rigid, or spring-like setting, using both a stiff and flexible performance. At baseline (i.e. shoes-only and for each vAFO, a 3D-gait analysis and 6-minute walk test with breath-gas analysis were performed at comfortable speed. Lower limb joint kinematics and kinetics were calculated. From the 6-minute walk test, walking speed and the net energy cost were determined. A generalized estimation equation (p<0.05 was used to analyze the effects of different conditions. Compared to shoes-only, all vAFOs improved the knee angle and net moment similarly. Ankle power generation and work were preserved only by the spring-like vAFOs. All vAFOs decreased the net energy cost compared to shoes-only, but no differences were found between vAFOs, showing that the effects of spring-like vAFOs to promote push-off power did not lead to greater reductions in walking energy cost. These findings suggest that, in this specific group of children with spastic CP, the vAFO stiffness that maximizes gait efficiency is primarily determined by its effect on knee kinematics and kinetics rather than by its effect on push-off power

  5. Ankle replacement

    Science.gov (United States)

    Ankle arthroplasty - total; Total ankle arthroplasty; Endoprosthetic ankle replacement; Ankle surgery ... You may not be able to have a total ankle replacement if you have had ankle joint infections in ...

  6. Acute and prolonged reduction in joint stiffness in humans after exhausting stretch-shortening cycle exercise.

    Science.gov (United States)

    Kuitunen, S; Avela, J; Kyröläinen, H; Nicol, C; Komi, P V

    2002-11-01

    The purpose of the present study was to examine the acute and long-term fatigue effects of exhausting stretch-shortening cycle (SSC) exercise on the stiffness of ankle and knee joints. Five subjects were fatigued on a sledge apparatus by 100 maximal rebound jumps followed by continuous submaximal jumping until complete exhaustion. Neuromuscular fatigue effects were examined in submaximal hopping (HOP) and in maximal drop jumps (DJ) from 35 (DJ35) and 55 cm (DJ55) heights on a force plate. Additional force and reflex measurements were made using an ankle ergometer. Jumping tests and ankle ergometer tests were carried out before, immediately after, 2 h (2H), 2 days and 7 days (7D) after the SSC exercise. Kinematics, force and electromyography (EMG) recordings were complemented with inverse dynamics, which was used to calculate joint moments. The quotient of changes in joint moment divided by changes in joint angle was used as a value of joint stiffness (JS). In addition, blood lactate concentrations and serum creatine kinase activities were determined. The exercise induced a clear decrease in knee joint stiffness by [mean (SD)] 29 (13)% (P < 0.05) in HOP, 31 (6)% (P < 0.05) in DJ35 and 34 (14)% (P < 0.05) in DJ55. A similar trend was observed in the ankle joint stiffness with significant post-exercise reductions of 22 (8)% (P < 0.05) in DJ35 and of 27 (19)% (P < 0.05) at 2H in DJ55. The subsequent recovery of JS was slow and in some cases incomplete still at 7D. Generally, all the EMG parameters were fully recovered by 2H, whereas the force recovery was still incomplete at this time. These data indicate that the immediate reduction in JS was probably related to the effects of both central (neural) and peripheral (metabolic) fatigue, whereas the prolonged impairment was probably due to peripheral fatigue (muscle damage).

  7. Characterizing stiffness of human prostates using acoustic radiation force.

    Science.gov (United States)

    Zhai, Liang; Madden, John; Foo, Wen-Chi; Mouraviev, Vladimir; Polascik, Thomas J; Palmeri, Mark L; Nightingale, Kathryn R

    2010-10-01

    Acoustic Radiation Force Impulse (ARFI) imaging has been previously reported to portray normal anatomic structures and pathologies in ex vivo human prostates with good contrast and resolution. These findings were based on comparison with histological slides and McNeal's zonal anatomy. In ARFI images, the central zone (CZ) appears darker (smaller displacement) than other anatomic zones and prostate cancer (PCa) is darker than normal tissue in the peripheral zone (PZ). Since displacement amplitudes in ARFI images are determined by both the underlying tissue stiffness and the amplitude of acoustic radiation force that varies with acoustic attenuation, one question that arises is how the relative displacements in prostate ARFI images are related to the underlying prostatic tissue stiffness. In linear, isotropic elastic materials and in tissues that are relatively uniform in acoustic attenuation (e.g., liver), relative displacement in ARFI images has been shown to be correlated with underlying tissue stiffness. However, the prostate is known to be heterogeneous. Variations in acoustic attenuation of prostatic structures could confound the interpretation of ARFI images due to the associated variations in the applied acoustic radiation force. Therefore, in this study, co-registered three-dimensional (3D) ARFI datasets and quantitative shear wave elasticity imaging (SWEI) datasets were acquired in freshly-excised human prostates to investigate the relationship between displacement amplitudes in ARFI prostate images and the matched reconstructed shear moduli. The lateral time-to-peak (LTTP) algorithm was applied to the SWEI data to compute the shear-wave speed and reconstruct the shear moduli. Five types of prostatic tissue (PZ, CZ, transition zone (TZ) and benign prostatic hyperplasia (BPH), PCa and atrophy) were identified, whose shear moduli were quantified to be 4.1 +/- 0.8 kPa, 9.9 +/- 0.9 kPa, 4.8 +/- 0.6 kPa, 10.0 +/- 1.0 kPa and 8.0 kPa, respectively. Linear

  8. Characterizing the stiffness of Human Prostates using Acoustic Radiation Force

    Science.gov (United States)

    Zhai, Liang; Madden, John; Foo, Wen-Chi; Mouraviev, Vladimir; Polascik, Thomas J.; Palmeri, Mark L.; Nightingale, Kathryn R.

    2012-01-01

    Acoustic Radiation Force Impulse (ARFI) imaging has been previously reported to portray normal anatomic structures and pathologies in ex vivo human prostates with good contrast and resolution. These findings were based on comparison with histological slides and McNeal’s zonal anatomy. In ARFI images, the central zone (CZ) appears darker (smaller displacement) than other anatomic zones, and prostate cancer (PCa) is darker than normal tissue in the peripheral zone (PZ). Since displacement amplitudes in ARFI images are determined by both the underlying tissue stiffness and the amplitude of acoustic radiation force which varies with acoustic attenuation, one question that arises is: how are the relative displacements in prostate ARFI images related to the underlying prostatic tissue stiffness? In linear, isotropic elastic materials and in tissues that are relatively uniform in acoustic attenuation (e.g. liver), relative displacement in ARFI images has been shown to be correlated with underlying tissue stiffness. However, the prostate is known to be heterogeneous. Variations in acoustic attenuation of prostatic structures could confound the interpretation of ARFI images due to the associated variations in the applied acoustic radiation force. Therefore, in this study, co-registered three-dimensional (3D) ARFI datasets and quantitative shear wave elasticity imaging (SWEI) datasets were acquired in freshly excised human prostates to investigate the relationship between displacement amplitudes in ARFI prostate images and the matched reconstructed shear moduli. The lateral time-to-peak (LTTP) algorithm was applied to the SWEI data to compute the shear wave speed and reconstruct the shear moduli. Five types of prostatic tissue (PZ, CZ, transition zone (TZ) and benign prostatic hyperplasia (BPH), PCa, and atrophy) were identified, whose shear moduli were quantified to be 4.1±0.8 kPa, 9.9±0.9 kPa, 4.8±0.6 kPa, 10.0±1.0 kPa and 8.0 kPa, respectively. Linear regression was

  9. Stiffness of the human foot and evolution of the transverse arch

    OpenAIRE

    Venkadesan, Madhusudhan; Dias, Marcelo A.; Singh, Dhiraj K.; Bandi, Mahesh M.; Mandre, Shreyas

    2017-01-01

    Foot stiffness underlies its mechanical function, and is central to the evolution of human bipedal locomotion. The stiff and propulsive human foot has two distinct arches, the longitudinal and transverse. By contrast, the feet of non-human primates are flat and softer. Current understanding of foot stiffness is based on studies that focus solely on the longitudinal arch, and little is known about the mechanical function of the transverse arch. However, common experience suggests that transver...

  10. Speed-related spinal excitation from ankle dorsiflexors to knee extensors during human walking

    DEFF Research Database (Denmark)

    Iglesias, Caroline; Nielsen, Jens Bo; Marchand-Pauvert, Véronique

    2008-01-01

    Automatic adjustments of muscle activity throughout the body are required for the maintenance of balance during human walking. One mechanism that is likely to contribute to this control is the heteronymous spinal excitation between human ankle dorsiflexors and knee extensors (CPQ-reflex). Here, we...

  11. The Split Second Effect: The Mechanism of How Equinus Can Damage the Human Foot and Ankle

    Science.gov (United States)

    Amis, James

    2016-01-01

    We are currently in the process of discovering that many, if not the majority, of the non-traumatic acquired adult foot and ankle problems are caused by a singular etiology: non-neuromuscular equinus or the isolated gastrocnemius contracture. There is no question that this biomechanical association exists and in time much more will be uncovered. There are three basic questions that must be answered: why would our calves tighten as we normally age, how does a tight calf, or equinus, actually cause problems remotely in the foot and ankle, and how do the forces produced by equinus cause so many seemingly unrelated pathologies in the foot and ankle? The purpose of this paper is to address the second question: how does a tight calf mechanically cause problems remotely in the foot and ankle? There has been little evidence in the literature addressing the biomechanical mechanisms by which equinus creates damaging forces upon the foot and ankle, and as a result, a precise, convincing mechanism is still lacking. Thus, the mere concept that equinus has anything to do with foot pathology is generally unknown or disregarded. The split second effect, described here, defines exactly how the silent equinus contracture creates incremental and significant damage and injury to the human foot and ankle resulting in a wide variety of pathological conditions. The split second effect is a dissenting theory based on 30 years of clinical and academic orthopedic foot and ankle experience, keen clinical observation along the way, and review of the developing literature, culminating in examination of many hours of slow motion video of normal and abnormal human gait. To my knowledge, no one has ever described the mechanism in detail this precise. PMID:27512692

  12. The Split Second Effect: The Mechanism of How Equinus Damages the Human Foot and Ankle

    Directory of Open Access Journals (Sweden)

    James Amis

    2016-07-01

    Full Text Available We are currently in the process of discovering that many, if not the majority, of non-traumatic acquired adult foot and ankle problems are caused by a singular etiology: equinus or the isolated gastrocnemius contracture. There is no question that this biomechanical association exists and in time much more will be uncovered. There are three basic questions that must be answered: why would our calves tighten as we normally age, how does a tight calf, or equinus, actually cause problems remotely in the foot and ankle, and how do the forces produced by equinus cause each individual resulting specific pathology in the foot and ankle? The purpose of this paper is to address the second question: how does a tight calf mechanically cause problems remotely in the foot and ankle? There has been little evidence in the literature addressing the biomechanical mechanisms by which equinus creates damaging forces upon the foot and ankle and as a result a precise, convincing mechanism is still lacking. Thus the mere concept that equinus has anything to do with foot pathology is generally unknown or disregarded. The split second effect, described here, defines exactly how the silent equinus contracture creates incremental and significant damage and injury to the human foot and ankle resulting in a wide variety of pathological conditions. The split second effect is a dissenting theory based on 30 years of clinical and academic orthopaedic foot and ankle experience, keen clinical observation along the way, and review of the developing literature, culminating in examination of many hours of slow motion video of normal and abnormal human gait. To my knowledge, no one has ever described the mechanism in detail this precise.

  13. Ankle Cheilectomy

    Science.gov (United States)

    ... your primary doctor. Treatments of the Ankle Achilles Tendinosis Surgery Achilles Tendon Rupture Surgery Ankle Arthrodesis Ankle ... for Osteochondral Lesions of the Talus Insertional Achilles Tendinosis Surgery Lateral Ankle Ligament Reconstruction Lateral Ankle Stabilization ...

  14. Modulation of recurrent inhibition from knee extensors to ankle motoneurones during human walking

    DEFF Research Database (Denmark)

    Lamy, Jean-Charles; Iglesias, Caroline; Lackmy, Alexandra

    2008-01-01

    The neural control for muscle coordination during human locomotion involves spinal and supraspinal networks, but little is known about the exact mechanisms implicated. The present study focused on modulation of heteronymous recurrent inhibition from knee extensors to ankle motoneurones at different...... times in the gait cycle, when quadriceps (Quad) muscle activity overlaps that in tibialis anterior (TA) and soleus (Sol). The effects of femoral nerve stimulation on ankle motoneurones were investigated during treadmill walking and during tonic co-contraction of Quad and TA/Sol while standing. Recurrent...

  15. Does ankle joint power reflect type of muscle action of soleus and gastrocnemius during walking in cats and humans?

    Science.gov (United States)

    Cronin, Neil J; Prilutsky, Boris I; Lichtwark, Glen A; Maas, Huub

    2013-04-26

    The main objective of this paper is to highlight the difficulties of identifying shortening and lengthening contractions based on analysis of power produced by resultant joint moments. For that purpose, we present net ankle joint powers and muscle fascicle/muscle-tendon unit (MTU) velocities for medial gastrocnemius (MG) and soleus (SO) muscles during walking in species of different size (humans and cats). For the cat, patterns of ankle joint power and MTU velocity of MG and SO during stance were similar: negative power (ankle moment×angular velocitypower (generation of mechanical energy) was found during MTU shortening. This was also found for the general fascicle velocity pattern in SO. In contrast, substantial differences between ankle joint power and fascicle velocity patterns were observed for MG muscle. In humans, like cats, the patterns of ankle joint power and MTU velocity of SO and MG were similar. Unlike the cat, there were substantial differences between patterns of fascicle velocity and ankle joint power during stance in both muscles. These results indicate that during walking, only a small fraction of mechanical work of the ankle moment is either generated or absorbed by the muscle fascicles, thus confirming the contribution of in-series elastic structures and/or energy transfer via two-joint muscles. We conclude that ankle joint negative power does not necessarily indicate eccentric action of muscle fibers and that positive power cannot be exclusively attributed to muscle concentric action, especially in humans.

  16. Matrix Stiffness Corresponding to Strictured Bowel Induces a Fibrogenic Response in Human Colonic Fibroblasts

    Science.gov (United States)

    Johnson, Laura A.; Rodansky, Eva S.; Sauder, Kay L.; Horowitz, Jeffrey C.; Mih, Justin D.; Tschumperlin, Daniel J.; Higgins, Peter D.

    2013-01-01

    Background Crohn’s disease is characterized by repeated cycles of inflammation and mucosal healing which ultimately progress to intestinal fibrosis. This inexorable progression towards fibrosis suggests that fibrosis becomes inflammation-independent and auto-propagative. We hypothesized that matrix stiffness regulates this auto-propagation of intestinal fibrosis. Methods The stiffness of fresh ex vivo samples from normal human small intestine, Crohn’s disease strictures, and the unaffected margin were measured with a microelastometer. Normal human colonic fibroblasts were cultured on physiologically normal or pathologically stiff matrices corresponding to the physiological stiffness of normal or fibrotic bowel. Cellular response was assayed for changes in cell morphology, α-smooth muscle actin (αSMA) staining, and gene expression. Results Microelastometer measurements revealed a significant increase in colonic tissue stiffness between normal human colon and Crohn’s strictures as well as between the stricture and adjacent tissue margin. In Ccd-18co cells grown on stiff matrices corresponding to Crohn’s strictures, cellular proliferation increased. Pathologic stiffness induced a marked change in cell morphology and increased αSMA protein expression. Growth on a stiff matrix induced fibrogenic gene expression, decreased matrix metalloproteinase and pro-inflammatory gene expression, and was associated with nuclear localization of the transcriptional cofactor MRTF-A. Conclusions Matrix stiffness, representative of the pathological stiffness of Crohn’s strictures, activates human colonic fibroblasts to a fibrogenic phenotype. Matrix stiffness affects multiple pathways suggesting the mechanical properties of the cellular environment are critical to fibroblast function and may contribute to autopropagation of intestinal fibrosis in the absence of inflammation, thereby contributing to the intractable intestinal fibrosis characteristic of Crohn’s disease. PMID

  17. Estimation of quasi-stiffness of the human knee in the stance phase of walking.

    Directory of Open Access Journals (Sweden)

    Kamran Shamaei

    Full Text Available Biomechanical data characterizing the quasi-stiffness of lower-limb joints during human locomotion is limited. Understanding joint stiffness is critical for evaluating gait function and designing devices such as prostheses and orthoses intended to emulate biological properties of human legs. The knee joint moment-angle relationship is approximately linear in the flexion and extension stages of stance, exhibiting nearly constant stiffnesses, known as the quasi-stiffnesses of each stage. Using a generalized inverse dynamics analysis approach, we identify the key independent variables needed to predict knee quasi-stiffness during walking, including gait speed, knee excursion, and subject height and weight. Then, based on the identified key variables, we used experimental walking data for 136 conditions (speeds of 0.75-2.63 m/s across 14 subjects to obtain best fit linear regressions for a set of general models, which were further simplified for the optimal gait speed. We found R(2 > 86% for the most general models of knee quasi-stiffnesses for the flexion and extension stages of stance. With only subject height and weight, we could predict knee quasi-stiffness for preferred walking speed with average error of 9% with only one outlier. These results provide a useful framework and foundation for selecting subject-specific stiffness for prosthetic and exoskeletal devices designed to emulate biological knee function during walking.

  18. Finite element based nonlinear normalization of human lumbar intervertebral disc stiffness to account for its morphology.

    Science.gov (United States)

    Maquer, Ghislain; Laurent, Marc; Brandejsky, Vaclav; Pretterklieber, Michael L; Zysset, Philippe K

    2014-06-01

    Disc degeneration, usually associated with low back pain and changes of intervertebral stiffness, represents a major health issue. As the intervertebral disc (IVD) morphology influences its stiffness, the link between mechanical properties and degenerative grade is partially lost without an efficient normalization of the stiffness with respect to the morphology. Moreover, although the behavior of soft tissues is highly nonlinear, only linear normalization protocols have been defined so far for the disc stiffness. Thus, the aim of this work is to propose a nonlinear normalization based on finite elements (FE) simulations and evaluate its impact on the stiffness of human anatomical specimens of lumbar IVD. First, a parameter study involving simulations of biomechanical tests (compression, flexion/extension, bilateral torsion and bending) on 20 FE models of IVDs with various dimensions was carried out to evaluate the effect of the disc's geometry on its compliance and establish stiffness/morphology relations necessary to the nonlinear normalization. The computed stiffness was then normalized by height (H), cross-sectional area (CSA), polar moment of inertia (J) or moments of inertia (Ixx, Iyy) to quantify the effect of both linear and nonlinear normalizations. In the second part of the study, T1-weighted MRI images were acquired to determine H, CSA, J, Ixx and Iyy of 14 human lumbar IVDs. Based on the measured morphology and pre-established relation with stiffness, linear and nonlinear normalization routines were then applied to the compliance of the specimens for each quasi-static biomechanical test. The variability of the stiffness prior to and after normalization was assessed via coefficient of variation (CV). The FE study confirmed that larger and thinner IVDs were stiffer while the normalization strongly attenuated the effect of the disc geometry on its stiffness. Yet, notwithstanding the results of the FE study, the experimental stiffness showed consistently

  19. Arterial stiffness, as monitored by cardio–ankle vascular index, is affected by obstructive sleep apnea, blood glucose control, and body weight – a case with 8 years follow up

    Science.gov (United States)

    Shimizu, Kazuhiro; Yamamoto, Tomoyuki; Shirai, Kohji

    2016-01-01

    The cardio–ankle vascular index (CAVI) is an indicator of arterial stiffness from the heart to the ankles. The CAVI increases as arteriosclerosis progresses, but it can be decreased by appropriate treatment. There are several risk factors for coronary artery disease, however, the degree of stress caused by each separate risk factor to arteries cannot be assessed. CAVI increases with age and according to the severity of atherosclerosis. We found that CAVI also changes in response to the control of risk factors, which may be associated with the functional stiffness of arteries. CAVI can be a useful indicator of risk control for coronary artery disease. We followed a patient aged 71 years who had diabetes mellitus and obstructive sleep apnea (OSA) by measuring CAVI for 8 years from age 63. He underwent coronary artery bypass grafting due to angina pectoris when he was 63 years old. Before coronary artery bypass grafting, CAVI was 11.8 on the right and 11.5 on the left. Three years later he was found to have OSA and received treatment with continuous positive airway pressure. There was a marked improvement in CAVI after continuous positive airway pressure (age 68; right 10.4, left 10.2). However, following a gradual increase in body weight and worsening of diabetes mellitus, CAVI showed an increasing trend. CAVI decreased with biguanides treatment, but increased again with an increase in body weight. In conclusion, CAVI responded to the patient’s conditions including obesity, diabetes mellitus, and OSA. CAVI is not only a marker of arterial stiffness, but can also be a useful indicator of physiological status; it may be effective in total risk control for coronary artery disease. PMID:27563259

  20. Evidence for a time-invariant phase variable in human ankle control.

    Directory of Open Access Journals (Sweden)

    Robert D Gregg

    Full Text Available Human locomotion is a rhythmic task in which patterns of muscle activity are modulated by state-dependent feedback to accommodate perturbations. Two popular theories have been proposed for the underlying embodiment of phase in the human pattern generator: a time-dependent internal representation or a time-invariant feedback representation (i.e., reflex mechanisms. In either case the neuromuscular system must update or represent the phase of locomotor patterns based on the system state, which can include measurements of hundreds of variables. However, a much simpler representation of phase has emerged in recent designs for legged robots, which control joint patterns as functions of a single monotonic mechanical variable, termed a phase variable. We propose that human joint patterns may similarly depend on a physical phase variable, specifically the heel-to-toe movement of the Center of Pressure under the foot. We found that when the ankle is unexpectedly rotated to a position it would have encountered later in the step, the Center of Pressure also shifts forward to the corresponding later position, and the remaining portion of the gait pattern ensues. This phase shift suggests that the progression of the stance ankle is controlled by a biomechanical phase variable, motivating future investigations of phase variables in human locomotor control.

  1. Human leg model predicts ankle muscle-tendon morphology, state, roles and energetics in walking.

    Directory of Open Access Journals (Sweden)

    Pavitra Krishnaswamy

    2011-03-01

    Full Text Available A common feature in biological neuromuscular systems is the redundancy in joint actuation. Understanding how these redundancies are resolved in typical joint movements has been a long-standing problem in biomechanics, neuroscience and prosthetics. Many empirical studies have uncovered neural, mechanical and energetic aspects of how humans resolve these degrees of freedom to actuate leg joints for common tasks like walking. However, a unifying theoretical framework that explains the many independent empirical observations and predicts individual muscle and tendon contributions to joint actuation is yet to be established. Here we develop a computational framework to address how the ankle joint actuation problem is resolved by the neuromuscular system in walking. Our framework is founded upon the proposal that a consideration of both neural control and leg muscle-tendon morphology is critical to obtain predictive, mechanistic insight into individual muscle and tendon contributions to joint actuation. We examine kinetic, kinematic and electromyographic data from healthy walking subjects to find that human leg muscle-tendon morphology and neural activations enable a metabolically optimal realization of biological ankle mechanics in walking. This optimal realization (a corresponds to independent empirical observations of operation and performance of the soleus and gastrocnemius muscles, (b gives rise to an efficient load-sharing amongst ankle muscle-tendon units and (c causes soleus and gastrocnemius muscle fibers to take on distinct mechanical roles of force generation and power production at the end of stance phase in walking. The framework outlined here suggests that the dynamical interplay between leg structure and neural control may be key to the high walking economy of humans, and has implications as a means to obtain insight into empirically inaccessible features of individual muscle and tendons in biomechanical tasks.

  2. Human Leg Model Predicts Ankle Muscle-Tendon Morphology, State, Roles and Energetics in Walking

    Science.gov (United States)

    Krishnaswamy, Pavitra; Brown, Emery N.; Herr, Hugh M.

    2011-01-01

    A common feature in biological neuromuscular systems is the redundancy in joint actuation. Understanding how these redundancies are resolved in typical joint movements has been a long-standing problem in biomechanics, neuroscience and prosthetics. Many empirical studies have uncovered neural, mechanical and energetic aspects of how humans resolve these degrees of freedom to actuate leg joints for common tasks like walking. However, a unifying theoretical framework that explains the many independent empirical observations and predicts individual muscle and tendon contributions to joint actuation is yet to be established. Here we develop a computational framework to address how the ankle joint actuation problem is resolved by the neuromuscular system in walking. Our framework is founded upon the proposal that a consideration of both neural control and leg muscle-tendon morphology is critical to obtain predictive, mechanistic insight into individual muscle and tendon contributions to joint actuation. We examine kinetic, kinematic and electromyographic data from healthy walking subjects to find that human leg muscle-tendon morphology and neural activations enable a metabolically optimal realization of biological ankle mechanics in walking. This optimal realization (a) corresponds to independent empirical observations of operation and performance of the soleus and gastrocnemius muscles, (b) gives rise to an efficient load-sharing amongst ankle muscle-tendon units and (c) causes soleus and gastrocnemius muscle fibers to take on distinct mechanical roles of force generation and power production at the end of stance phase in walking. The framework outlined here suggests that the dynamical interplay between leg structure and neural control may be key to the high walking economy of humans, and has implications as a means to obtain insight into empirically inaccessible features of individual muscle and tendons in biomechanical tasks. PMID:21445231

  3. Fuzzy variable impedance control based on stiffness identification for human-robot cooperation

    Science.gov (United States)

    Mao, Dachao; Yang, Wenlong; Du, Zhijiang

    2017-06-01

    This paper presents a dynamic fuzzy variable impedance control algorithm for human-robot cooperation. In order to estimate the intention of human for co-manipulation, a fuzzy inference system is set up to adjust the impedance parameter. Aiming at regulating the output fuzzy universe based on the human arm’s stiffness, an online stiffness identification method is developed. A drag interaction task is conducted on a 5-DOF robot with variable impedance control. Experimental results demonstrate that the proposed algorithm is superior.

  4. Arterial stiffness, as monitored by cardio–ankle vascular index, is affected by obstructive sleep apnea, blood glucose control, and body weight – a case with 8 years follow up

    Directory of Open Access Journals (Sweden)

    Shimizu K

    2016-08-01

    Full Text Available Kazuhiro Shimizu,1 Tomoyuki Yamamoto,2,3 Kohji Shirai2,4 1Department of Internal Medicine, Toho University Sakura Medical Center, Chiba, Japan; 2Department of Vascular Function, Toho University Sakura Medical Center, Chiba, Japan; 3Biological Information Analysis Section, Fukuda Denshi Co., Ltd., Tokyo, Japan; 4Department of Internal Medicine, Mihama Hospital, Chiba, Japan Abstract: The cardio–ankle vascular index (CAVI is an indicator of arterial stiffness from the heart to the ankles. The CAVI increases as arteriosclerosis progresses, but it can be decreased by appropriate treatment. There are several risk factors for coronary artery disease, however, the degree of stress caused by each separate risk factor to arteries cannot be assessed. CAVI increases with age and according to the severity of atherosclerosis. We found that CAVI also changes in response to the control of risk factors, which may be associated with the functional stiffness of arteries. CAVI can be a useful indicator of risk control for coronary artery disease. We followed a patient aged 71 years who had diabetes mellitus and obstructive sleep apnea (OSA by measuring CAVI for 8 years from age 63. He underwent coronary artery bypass grafting due to angina pectoris when he was 63 years old. Before coronary artery bypass grafting, CAVI was 11.8 on the right and 11.5 on the left. Three years later he was found to have OSA and received treatment with continuous positive airway pressure. There was a marked improvement in CAVI after continuous positive airway pressure (age 68; right 10.4, left 10.2. However, following a gradual increase in body weight and worsening of diabetes mellitus, CAVI showed an increasing trend. CAVI decreased with biguanides treatment, but increased again with an increase in body weight. In conclusion, CAVI responded to the patient’s conditions including obesity, diabetes mellitus, and OSA. CAVI is not only a marker of arterial stiffness, but can also be a

  5. Elastic properties of Thiel-embalmed human ankle tendon and ligament.

    Science.gov (United States)

    Liao, Xiaochun; Kemp, Sandy; Corner, George; Eisma, Roos; Huang, Zhihong

    2015-10-01

    Thiel embalming is recommended as an alternative to formalin-based embalming because it preserves tissue elasticity, color, and flexibility in the long term, with low infection and toxicity risk. The degree to which Thiel embalming preserves elasticity has so far been assessed mainly by subjective scoring, with little quantitative verification. The aim of this study is to quantify the effect of Thiel embalming on the elastic properties of human ankle tendons and ligament. Biomechanical tensile tests were carried out on six Thiel-embalmed samples each of the peroneus longus, peroneus brevis, and calcaneal tendons, and the calcaneofibular ligament, with strain rates of 0.25%s(-1), 2%s(-1), and 8%s(-1). The stress-strain relationship was calculated from the force-extension response with cross-sectional area and gauge length. Young's modulus was determined from the stress-strain curve. The results showed that the tendon and ligament elasticity were lower after Thiel embalming than the literature values for fresh nonembalmed tendons and ligament. The biomechanical tensile test showed that the measured elasticity of Thiel-embalmed tendons and ligaments increased with the strain rate. The Thiel embalming method is useful for preserving human ankle tendons and ligaments for anatomy and surgery teaching and research, but users need to be aware of its softening effects. The method retains the mechanical strain rate effect on tendons and ligament. © 2015 Wiley Periodicals, Inc.

  6. Validity and reliability of clinical tests for assessing passive ankle stiffness Validade e confiabilidade de medidas clínicas para avaliação da rigidez passiva da articulação do tornozelo

    Directory of Open Access Journals (Sweden)

    Vanessa L. Araújo

    2011-04-01

    Full Text Available BACKGROUND: The presence of inadequate levels of passive ankle stiffness have been associated with the occurrence of movement disorders, the development of pathological conditions and the reduction in the performance of functional activities such as walking, running and jumping. Therefore, clinical tests to evaluate ankle stiffness may be useful for the physical therapy assessment. OBJECTIVES: To investigate the concurrent validity and the intra- and inter-examiner reliability of clinical measures developed to assess passive stiffness of the ankle joint during dorsiflexion movement. METHODS: Fifteen healthy participants underwent to test-retest evaluations of their ankles by two examiners. Two clinical measures were performed: 'position of first detectable resistance' and 'change in passive resistance torque'. The results of these tests were compared to the passive stiffness measured with an isokinetic dynamometer, in which the electromyography activity of specific muscles was monitored to ensure that the test was performed passively (gold standard measure. RESULTS: Pearson correlation coefficients ranged from r=-0.81 to -0.88 (pCONTEXTUALIZAÇÃO: Níveis inadequados de rigidez passiva do tornozelo têm sido associados à ocorrência de disfunções de movimento, ao desenvolvimento de patologias e à redução no desempenho em atividades como marcha, corrida e salto. Testes clínicos para investigar a rigidez dessa articulação podem ser úteis no processo de avaliação fisioterápica. OBJETIVOS: Investigar a validade concorrente e as confiabilidades intra e interexaminadores de medidas clínicas para avaliação da rigidez passiva do tornozelo durante o movimento de dorsiflexão. MÉTODOS: Quinze voluntários saudáveis foram submetidos a avaliações teste-reteste do tornozelo por dois examinadores. Duas medidas clínicas foram realizadas: "posição de primeira resistência detectável" e "mudança do torque passivo de resistência". Os

  7. An improved spinning lens test to determine the stiffness of the human lens

    Science.gov (United States)

    Burd, H.J.; Wilde, G.S.; Judge, S.J.

    2011-01-01

    It is widely accepted that age-related changes in lens stiffness are significant for the development of presbyopia. However, precise details on the relative importance of age-related changes in the stiffness of the lens, in comparison with other potential mechanisms for the development of presbyopia, have not yet been established. One contributing factor to this uncertainty is the paucity and variability of experimental data on lens stiffness. The available published data generally indicate that stiffness varies spatially within the lens and that stiffness parameters tend to increase with age. However, considerable differences exist between these published data sets, both qualitatively and quantitatively. The current paper describes new and improved methods, based on the spinning lens approach pioneered by Fisher, R.F. (1971) ‘The elastic constants of the human lens’, Journal of Physiology, 212, 147–180, to make measurements on the stiffness of the human lens. These new procedures have been developed in an attempt to eliminate, or at least substantially reduce, various systematic errors in Fisher’s original experiment. An improved test rig has been constructed and a new modelling procedure for determining lens stiffness parameters from observations made during the test has been devised. The experiment involves mounting a human lens on a vertical rotor so that the lens spins on its optical axis (typically at 1000 rpm). An automatic imaging system is used to capture the outline of the lens, while it is rotating, at pre-determined angular orientations. These images are used to quantify the deformations developed in the lens as a consequence of the centripetal forces induced by the rotation. Lens stiffness is inferred using axisymmetric finite element inverse analysis in which a nearly-incompressible neo-Hookean constitutive model is used to represent the mechanics of the lens. A numerical optimisation procedure is used to determine the stiffness parameters

  8. Human ankle plantar flexor muscle–tendon mechanics and energetics during maximum acceleration sprinting

    Science.gov (United States)

    Schache, Anthony G.; Brown, Nicholas A. T.; Pandy, Marcus G.

    2016-01-01

    Tendon elastic strain energy is the dominant contributor to muscle–tendon work during steady-state running. Does this behaviour also occur for sprint accelerations? We used experimental data and computational modelling to quantify muscle fascicle work and tendon elastic strain energy for the human ankle plantar flexors (specifically soleus and medial gastrocnemius) for multiple foot contacts of a maximal sprint as well as for running at a steady-state speed. Positive work done by the soleus and medial gastrocnemius muscle fascicles decreased incrementally throughout the maximal sprint and both muscles performed more work for the first foot contact of the maximal sprint (FC1) compared with steady-state running at 5 m s−1 (SS5). However, the differences in tendon strain energy for both muscles were negligible throughout the maximal sprint and when comparing FC1 to SS5. Consequently, the contribution of muscle fascicle work to stored tendon elastic strain energy was greater for FC1 compared with subsequent foot contacts of the maximal sprint and compared with SS5. We conclude that tendon elastic strain energy in the ankle plantar flexors is just as vital at the start of a maximal sprint as it is at the end, and as it is for running at a constant speed. PMID:27581481

  9. Role of the tranverse arch in stiffness of the human foot

    Science.gov (United States)

    Dias, Marcelo A.; Singh, Dhiraj K.; Bandi, Mahesh M.; Venkadesan, Madhusudhan; Mandre, Shreyas

    2015-03-01

    Human ancestors evolved from walking, around 6 million years (Ma) ago, to regular endurance running, around 2 Ma ago. Simultaneously, the feet evolved from a relatively flat structure like that of current day Chimpanzees (or our hands), to the modern human foot with two arches, a longitudinal and a transversal arch. The feet play a crucial role in locomotion by providing sufficient stiffness for propulsion, and being soft and pliable to absorb impacts and store energy elastically. Here we show that the transverse arch could play a central role in stiffness modulation. We first treat the foot as an elastic shell that is with intrinsic curvature. Calculations, numerics and physical experiments all show that for a foot-like shell, the stiffness has a power-law dependence on transverse curvature beyond a critical value. On the other hand, for purely longitudinally curved feet, or transverse curvature below the critical value, lead to low stiffness like a flat plate. Discrete realizations of a continuum shell, more closely resembling the human foot, also exhibit curvature induced stiffening. These results shed light on the role of the quintessentially human feature of a doubly arched foot, and suggest mechanical consequences of disorders such as a collapsed arch. HFSP RGY0091/2013.

  10. Measurement of the mechanical stiffness in cyclotorsion of the human eye

    NARCIS (Netherlands)

    H.J. Simonsz (Huib)

    1984-01-01

    textabstractWe have measured the stiffness in cyclotorsion of the human eye using a scleral suction contact ring mounted on a shaft fitted with an eddy current motor to provide the torque to turn the eye and a shaft-position-encoder to register the torsion. The relation proved to be almost linear wi

  11. Key Insights into Hand Biomechanics: Human Grip Stiffness Can Be Decoupled from Force by Cocontraction and Predicted from Electromyography

    Directory of Open Access Journals (Sweden)

    Hannes Höppner

    2017-05-01

    Full Text Available We investigate the relation between grip force and grip stiffness for the human hand with and without voluntary cocontraction. Apart from gaining biomechanical insight, this issue is particularly relevant for variable-stiffness robotic systems, which can independently control the two parameters, but for which no clear methods exist to design or efficiently exploit them. Subjects were asked in one task to produce different levels of force, and stiffness was measured. As expected, this task reveals a linear coupling between force and stiffness. In a second task, subjects were then asked to additionally decouple stiffness from force at these force levels by using cocontraction. We measured the electromyogram from relevant groups of muscles and analyzed the possibility to predict stiffness and force. Optical tracking was used for avoiding wrist movements. We found that subjects were able to decouple grip stiffness from force when using cocontraction on average by about 20% of the maximum measured stiffness over all force levels, while this ability increased with the applied force. This result contradicts the force–stiffness behavior of most variable-stiffness actuators. Moreover, we found the thumb to be on average twice as stiff as the index finger and discovered that intrinsic hand muscles predominate our prediction of stiffness, but not of force. EMG activity and grip force allowed to explain 72 ± 12% of the measured variance in stiffness by simple linear regression, while only 33 ± 18% variance in force. Conclusively the high signal-to-noise ratio and the high correlation to stiffness of these muscles allow for a robust and reliable regression of stiffness, which can be used to continuously teleoperate compliance of modern robotic hands.

  12. Key Insights into Hand Biomechanics: Human Grip Stiffness Can Be Decoupled from Force by Cocontraction and Predicted from Electromyography

    Science.gov (United States)

    Höppner, Hannes; Große-Dunker, Maximilian; Stillfried, Georg; Bayer, Justin; van der Smagt, Patrick

    2017-01-01

    We investigate the relation between grip force and grip stiffness for the human hand with and without voluntary cocontraction. Apart from gaining biomechanical insight, this issue is particularly relevant for variable-stiffness robotic systems, which can independently control the two parameters, but for which no clear methods exist to design or efficiently exploit them. Subjects were asked in one task to produce different levels of force, and stiffness was measured. As expected, this task reveals a linear coupling between force and stiffness. In a second task, subjects were then asked to additionally decouple stiffness from force at these force levels by using cocontraction. We measured the electromyogram from relevant groups of muscles and analyzed the possibility to predict stiffness and force. Optical tracking was used for avoiding wrist movements. We found that subjects were able to decouple grip stiffness from force when using cocontraction on average by about 20% of the maximum measured stiffness over all force levels, while this ability increased with the applied force. This result contradicts the force–stiffness behavior of most variable-stiffness actuators. Moreover, we found the thumb to be on average twice as stiff as the index finger and discovered that intrinsic hand muscles predominate our prediction of stiffness, but not of force. EMG activity and grip force allowed to explain 72 ± 12% of the measured variance in stiffness by simple linear regression, while only 33 ± 18% variance in force. Conclusively the high signal-to-noise ratio and the high correlation to stiffness of these muscles allow for a robust and reliable regression of stiffness, which can be used to continuously teleoperate compliance of modern robotic hands. PMID:28588472

  13. On the Value of Estimating Human Arm Stiffness during Virtual Teleoperation with Robotic Manipulators

    Directory of Open Access Journals (Sweden)

    Jacopo Buzzi

    2017-09-01

    Full Text Available Teleoperated robotic systems are widely spreading in multiple different fields, from hazardous environments exploration to surgery. In teleoperation, users directly manipulate a master device to achieve task execution at the slave robot side; this interaction is fundamental to guarantee both system stability and task execution performance. In this work, we propose a non-disruptive method to study the arm endpoint stiffness. We evaluate how users exploit the kinetic redundancy of the arm to achieve stability and precision during the execution of different tasks with different master devices. Four users were asked to perform two planar trajectories following virtual tasks using both a serial and a parallel link master device. Users' arm kinematics and muscular activation were acquired and combined with a user-specific musculoskeletal model to estimate the joint stiffness. Using the arm kinematic Jacobian, the arm end-point stiffness was derived. The proposed non-disruptive method is capable of estimating the arm endpoint stiffness during the execution of virtual teleoperated tasks. The obtained results are in accordance with the existing literature in human motor control and show, throughout the tested trajectory, a modulation of the arm endpoint stiffness that is affected by task characteristics and hand speed and acceleration.

  14. Stiffness of hyaluronic acid gels containing liver extracellular matrix supports human hepatocyte function and alters cell morphology.

    Science.gov (United States)

    Deegan, Daniel B; Zimmerman, Cynthia; Skardal, Aleksander; Atala, Anthony; Shupe, Thomas D

    2015-03-01

    Tissue engineering and cell based liver therapies have utilized primary hepatocytes with limited success due to the failure of hepatocytes to maintain their phenotype in vitro. In order to overcome this challenge, hyaluronic acid (HA) cell culture substrates were formulated to closely mimic the composition and stiffness of the normal liver cellular microenvironment. The stiffness of the substrate was modulated by adjusting HA hydrogel crosslinking. Additionally, the repertoire of bioactive molecules within the HA substrate was bolstered by supplementation with normal liver extracellular matrix (ECM). Primary human hepatocyte viability and phenotype were determined over a narrow physiologically relevant range of substrate stiffnesses from 600 to 4600Pa in both the presence and absence of liver ECM. Cell attachment, viability, and organization of the actin cytoskeleton improved with increased stiffness up to 4600Pa. These differences were not evident in earlier time points or substrates containing only HA. However, gene expression for the hepatocyte markers hepatocyte nuclear factor 4 alpha (HNF4α) and albumin significantly decreased on the 4600Pa stiffness at day 7 indicating that cells may not have maintained their phenotype long-term at this stiffness. Function, as measured by albumin secretion, varied with both stiffness and time in culture and peaked at day 7 at the 1200Pa stiffness, slightly below the stiffness of normal liver ECM at 3000Pa. Overall, gel stiffness affected primary human hepatocyte cell adhesion, functional marker expression, and morphological characteristics dependent on both the presence of liver ECM in gel substrates and time in culture.

  15. Arterial stiffness is inversely associated with a better running record in a full course marathon race

    OpenAIRE

    Jung, Su-Jeen; Park, Jae-Hyoung; Lee, Sewon

    2014-01-01

    [Purpose] Arterial stiffness is an independent predictor of cardiovascular risk and may contribute to reduced running capacity in humans. This study investigated the relationship between course record and arterial stiffness in marathoners who participated in the Seoul International Marathon in 2012. [Methods] A total of 30 amateur marathoners (Males n = 28, Females n = 2, mean age = 51.6 ± 8.3 years) were assessed before and after the marathon race. Brachial-ankle pulse wave velocity (ba-PWV)...

  16. Tendon elastic strain energy in the human ankle plantar-flexors and its role with increased running speed.

    Science.gov (United States)

    Lai, Adrian; Schache, Anthony G; Lin, Yi-Chung; Pandy, Marcus G

    2014-09-01

    The human ankle plantar-flexors, the soleus and gastrocnemius, utilize tendon elastic strain energy to reduce muscle fiber work and optimize contractile conditions during running. However, studies to date have considered only slow to moderate running speeds up to 5 m s(-1). Little is known about how the human ankle plantar-flexors utilize tendon elastic strain energy as running speed is advanced towards maximum sprinting. We used data obtained from gait experiments in conjunction with musculoskeletal modeling and optimization techniques to calculate muscle-tendon unit (MTU) work, tendon elastic strain energy and muscle fiber work for the ankle plantar-flexors as participants ran at five discrete steady-state speeds ranging from jogging (~2 m s(-1)) to sprinting (≥8 m s(-1)). As running speed progressed from jogging to sprinting, the contribution of tendon elastic strain energy to the positive work generated by the MTU increased from 53% to 74% for the soleus and from 62% to 75% for the gastrocnemius. This increase was facilitated by greater muscle activation and the relatively isometric behavior of the soleus and gastrocnemius muscle fibers. Both of these characteristics enhanced tendon stretch and recoil, which contributed to the bulk of the change in MTU length. Our results suggest that as steady-state running speed is advanced towards maximum sprinting, the human ankle plantar-flexors continue to prioritize the storage and recovery of tendon elastic strain energy over muscle fiber work.

  17. Estimation of quasi-stiffness of the human hip in the stance phase of walking.

    Directory of Open Access Journals (Sweden)

    Kamran Shamaei

    Full Text Available This work presents a framework for selection of subject-specific quasi-stiffness of hip orthoses and exoskeletons, and other devices that are intended to emulate the biological performance of this joint during walking. The hip joint exhibits linear moment-angular excursion behavior in both the extension and flexion stages of the resilient loading-unloading phase that consists of terminal stance and initial swing phases. Here, we establish statistical models that can closely estimate the slope of linear fits to the moment-angle graph of the hip in this phase, termed as the quasi-stiffness of the hip. Employing an inverse dynamics analysis, we identify a series of parameters that can capture the nearly linear hip quasi-stiffnesses in the resilient loading phase. We then employ regression analysis on experimental moment-angle data of 216 gait trials across 26 human adults walking over a wide range of gait speeds (0.75-2.63 m/s to obtain a set of general-form statistical models that estimate the hip quasi-stiffnesses using body weight and height, gait speed, and hip excursion. We show that the general-form models can closely estimate the hip quasi-stiffness in the extension (R(2 = 92% and flexion portions (R(2 = 89% of the resilient loading phase of the gait. We further simplify the general-form models and present a set of stature-based models that can estimate the hip quasi-stiffness for the preferred gait speed using only body weight and height with an average error of 27% for the extension stage and 37% for the flexion stage.

  18. A critical study on the experimental determination of stiffness and viscosity of the human triceps surae by free vibration methods.

    Science.gov (United States)

    París-García, Federico; Barroso, Alberto; Cañas, José; Ribas, Juan; París, Federico

    2013-09-01

    Muscles and tendons play an important role in human performance. Their mechanical behaviour can be described by analytical/numerical models including springs and dampers. Free vibration techniques are a widely used approach to the in vivo determination of stiffness and viscosity of muscle-tendon complexes involved in sport movements. By considering the data reported in the literature, it appears that the visco-elastic properties of the triceps surae muscle-tendon complexes are independent of the modality in which free vibration is induced as well as they do not depend on the composition of the population of subjects submitted to the experiments. This research will critically discuss this important aspect focussing in particular on two studies documented in the literature. For this purpose, two equipments will be developed to reproduce literature experiments under the assumption that the oscillating part of the body behaves as a single-degree-of-freedom system: The governing degree of freedom is associated with the vertical displacement of the lower leg or with the rotation of the foot around the ankle articulation. Unlike literature, measurements are now conducted on the same population of subjects in order to draw more general conclusions on the real equivalence of results and validity of the mechanical properties determined experimentally. Free vibration tests are accurately simulated by analytical models describing the response of each vibrating system. It is found that if the two measurement protocols are applied to the same population of individuals as it is done in this study, values of visco-elastic properties of muscle-tendon complexes extracted from experimental data are significantly different, the differences presenting a convincing consistency. This result is in contrast with the literature and confirms the need to evaluate results of free vibration techniques by taking homogeneous bases of comparison.

  19. Muscle stiffness, strength loss, swelling and soreness following exercise-induced injury in humans.

    Science.gov (United States)

    Howell, J N; Chleboun, G; Conatser, R

    1993-01-01

    1. In order to study injury-related changes in muscle stiffness, injury to the elbow flexors of thirteen human subjects was induced by a regimen of eccentric exercise. 2. Passive stiffness over an intermediate range of elbow angles was measured with a device which held the relaxed arm of the subject in the horizontal plane and stepped it through the range of elbow angles from 90 deg to near full extension at 180 deg. The relation between static torque and elbow angle was quite linear over the first 50 deg and was taken as stiffness. 3. Stiffness over this range of angles more than doubled immediately after exercise and remained elevated for about 4 days, and may result from low level myofibrillar activation induced by muscle stretch. 4. Arm swelling was biphasic; arm circumference increased by about 3% immediately after exercise, fell back toward normal, then increased by as much as 9% and remained elevated for as long as 9 days. 5. Ultrasound imaging showed most of the swelling immediately following the exercise to be localized to the flexor muscle compartment; subsequent swelling involved other tissue compartments as well. 6. Muscle strength declined by almost 40% after the exercise and recovery was only slight 10 days later; the half-time of recovery appeared to be as long as 5-6 weeks. PMID:8229798

  20. Substratum Stiffness and Latrunculin B Regulate Matrix Gene and Protein Expression in Human Trabecular Meshwork Cells

    Science.gov (United States)

    Thomasy, Sara M.; Wood, Joshua A.; Kass, Philip H.; Murphy, Christopher J.

    2012-01-01

    Purpose. To determine the impact of substratum stiffness and latrunculin-B (Lat-B), on the expression of several matrix proteins that are associated with glaucoma. Methods. Human trabecular meshwork (HTM) cells were cultured on hydrogels possessing stiffness values mimicking those found in normal (5 kPa) and glaucomatous meshworks (75 kPa), or tissue culture polystyrene (TCP; >1 GPa). Cells were treated with 2.0 μM Lat-B in dimethyl sulfoxide (DMSO) or DMSO alone. RT-PCR was used to determine the impact of substratum stiffness and/or Lat-B treatment on the expression of secreted protein, acidic, cysteine rich (SPARC), myocilin, angiopoietin-like factor (ANGPTL)-7, and transglutaminase (TGM)-2. Immunofluorescence was used to assess changes in protein expression. Results. SPARC and myocilin mRNA expression were dramatically increased on the 75 kPa hydrogels and decreased on the 5 kPa hydrogels in comparison to TCP. In contrast, ANGPTL-7 mRNA and TGM-2 mRNA was decreased on the 75 kPa and 5 kPa hydrogels, respectively, in comparison with TCP. Treatment with Lat-B dramatically downregulated both SPARC and myocilin on 75 kPa hydrogels. In contrast, cells grown on TCP produced greater or similar amounts of SPARC and myocilin mRNA after Lat-B treatment. SPARC and myocilin protein expression paralleled changes in mRNA expression. Conclusions. Substratum stiffness impacts HTM matrix gene and protein expression and modulates the impact of Lat-B treatment on the expression of these matrix proteins. Integrating the use of biologically relevant substratum stiffness in the conduction of in vitro experiments gives important insights into HTM cell response to drugs that may more accurately predict responses observed in vivo. PMID:22247475

  1. Prostate tissue stiffness as measured with a resonance sensor system: a study on silicone and human prostate tissue in vitro.

    Science.gov (United States)

    Jalkanen, Ville; Andersson, Britt M; Bergh, Anders; Ljungberg, Börje; Lindahl, Olof A

    2006-07-01

    Prostate cancer is the most common form of cancer in men in Europe and in the USA. Some prostate tumours are stiffer than the surrounding normal tissue, and it could therefore be of interest to measure prostate tissue stiffness. Resonance sensor technology based on piezoelectric resonance detects variations in tissue stiffness due to a change in the resonance frequency. An impression-controlled resonance sensor system was used to detect stiffness in silicone rubber and in human prostate tissue in vitro using two parameters, both combinations of frequency change and force. Variations in silicone rubber stiffness due to the mixing ratio of the two components could be detected (pprostate tissue showed that there existed a statistically significant (MANOVA test, pprostates. Our results indicated that the resonance sensor could be used to detect stiffness variations in silicone and in human prostate tissue in vitro. This is promising for the development of a future diagnostic tool for prostate cancer.

  2. A universal ankle-foot prosthesis emulator for human locomotion experiments.

    Science.gov (United States)

    Caputo, Joshua M; Collins, Steven H

    2014-03-01

    Robotic prostheses have the potential to significantly improve mobility for people with lower-limb amputation. Humans exhibit complex responses to mechanical interactions with these devices, however, and computational models are not yet able to predict such responses meaningfully. Experiments therefore play a critical role in development, but have been limited by the use of product-like prototypes, each requiring years of development and specialized for a narrow range of functions. Here we describe a robotic ankle-foot prosthesis system that enables rapid exploration of a wide range of dynamical behaviors in experiments with human subjects. This emulator comprises powerful off-board motor and control hardware, a flexible Bowden cable tether, and a lightweight instrumented prosthesis, resulting in a combination of low mass worn by the human (0.96 kg) and high mechatronic performance compared to prior platforms. Benchtop tests demonstrated closed-loop torque bandwidth of 17 Hz, peak torque of 175 Nm, and peak power of 1.0 kW. Tests with an anthropomorphic pendulum "leg" demonstrated low interference from the tether, less than 1 Nm about the hip. This combination of low worn mass, high bandwidth, high torque, and unrestricted movement makes the platform exceptionally versatile. To demonstrate suitability for human experiments, we performed preliminary tests in which a subject with unilateral transtibial amputation walked on a treadmill at 1.25 ms-1 while the prosthesis behaved in various ways. These tests revealed low torque tracking error (RMS error of 2.8 Nm) and the capacity to systematically vary work production or absorption across a broad range (from -5 to 21 J per step). These results support the use of robotic emulators during early stage assessment of proposed device functionalities and for scientific study of fundamental aspects of human-robot interaction. The design of simple, alternate end-effectors would enable studies at other joints or with

  3. Design and Preliminary Evaluation of a Two DOFs Cable-Driven Ankle-Foot Prosthesis with Active Dorsiflexion-Plantarflexion and Inversion-Eversion.

    Science.gov (United States)

    Ficanha, Evandro Maicon; Ribeiro, Guilherme Aramizo; Dallali, Houman; Rastgaar, Mohammad

    2016-01-01

    This paper describes the design of an ankle-foot robotic prosthesis controllable in the sagittal and frontal planes. The prosthesis was designed to meet the mechanical characteristics of the human ankle including power, range of motion, and weight. To transfer the power from the motors and gearboxes to the ankle-foot mechanism, a Bowden cable system was used. The Bowden cable allows for optimal placement of the motors and gearboxes in order to improve gait biomechanics such as the metabolic energy cost and gait asymmetry during locomotion. Additionally, it allows flexibility in the customization of the device to amputees with different residual limb sizes. To control the prosthesis, impedance controllers in both sagittal and frontal planes were developed. The impedance controllers used torque feedback from strain gages installed on the foot. Preliminary evaluation was performed to verify the capability of the prosthesis to track the kinematics of the human ankle in two degrees of freedom (DOFs), the mechanical efficiency of the Bowden cable transmission, and the ability of the prosthesis to modulate the impedance of the ankle. Moreover, the system was characterized by describing the relationship between the stiffness of the impedance controllers to the actual stiffness of the ankle. Efficiency estimation showed 85.4% efficiency in the Bowden cable transmission. The prosthesis was capable of properly mimicking human ankle kinematics and changing its mechanical impedance in two DOFs in real time with a range of stiffness sufficient for normal human walking. In dorsiflexion-plantarflexion (DP), the stiffness ranged from 0 to 236 Nm/rad and in inversion-eversion (IE), the stiffness ranged from 1 to 33 Nm/rad.

  4. An EMG-to-force processing approach for determining ankle muscle forces during normal human gait.

    Science.gov (United States)

    Bogey, R A; Perry, J; Gitter, A J

    2005-09-01

    Muscle forces move our limbs. These forces must be estimated with indirect techniques, as direct measurements are neither generally possible nor practical. An electromyography (EMG)-to-force processing technique was developed. Ankle joint moments and, by extension, ankle muscle forces were calculated. The ankle moment obtained by inverse dynamics was calculated for ten normal adults during free speed gait. There was close correlation between inverse dynamics ankle moments and moments determined by the EMG-to-force processing approach. Muscle forces were determined. The gait peak Achilles tendon force occurred in late single limb support. Peak force observed (2.9 kN) closely matched values obtained where force transducers were used to obtain in vivo muscle forces (2.6 kN). The EMG-to-force processing model presented here appears to be a practical means to determine in vivo muscle forces.

  5. Improving human ankle joint position sense using an artificial tongue-placed tactile biofeedback

    CERN Document Server

    Vuillerme, N; Demongeot, J; Payan, Y; Vuillerme, Nicolas; Chenu, Olivier; Demongeot, Jacques; Payan, Yohan

    2006-01-01

    Proprioception is comprised of sensory input from several sources including muscle spindles, joint capsule, ligaments and skin. The purpose of the present experiment was to investigate whether the central nervous system was able to integrate an artificial biofeedback delivered through electrotactile stimulation of the tongue to improve proprioceptive acuity at the ankle joint. To address this objective, nine young healthy adults were asked to perform an active ankle-matching task with and without biofeedback. The underlying principle of the biofeedback consisted of supplying subjects with supplementary information about the position of their matching ankle position relative to their reference ankle position through a tongue-placed tactile output device (Tongue Display Unit). Measures of the overall accuracy and the variability of the positioning were determined using the absolute error and the variable error, respectively. Results showed more accurate and more consistent matching performances with than withou...

  6. Ankle ligament injuries

    Directory of Open Access Journals (Sweden)

    Per A.F.H. Renström

    1998-06-01

    Full Text Available Acute ankle ligament sprains are common injuries. The majority of these occur during athletic participation in the 15 to 35 year age range. Despite the frequency of the injury, diagnostic and treatment protocols have varied greatly. Lateral ligament complex injuries are by far the most common of the ankle sprains. Lateral ligament injuries typically occur during plantar flexion and inversion, which is the position of maximum stress on the anterotalofibular liagment (ATFL. For this reason, the ATFL is the most commonly torn ligament during an inversion injury. In more severe inversion injuries the calcaneofibular (CFL, posterotalofibular (PTFL and subtalar ligament can also be injured. Most acute lateral ankle ligament injuries recover quickly with nonoperative management. The treatment program, called "functional treatment," includes application of the RICE principle (rest, ice, compression, and elevation immediately after the injury, a short period of immobilization and protection with an elastic or inelastic tape or bandage, and early motion exercises followed by early weight bearing and neuromuscular ankle training. Proprioceptive training with a tilt board is commenced as soon as possible, usually after 3 to 4 weeks. The purpose is to improve the balance and neuromuscular control of the ankle. Sequelae after ankle ligament injuries are very common. As much as 10% to 30% of patients with a lateral ligament injury may have chronic symptoms. Symptoms usually include persistent synovitis or tendinitis, ankle stiffness, swelling, and pain, muscle weakness, and frequent giving-way. A well designed physical therapy program with peroneal strengthening and proprioceptive training, along with bracing and/or taping can alleviate instability problems in most patients. For cases of chronic instability that are refractory to bracing and external support, surgical treatment can be explored. If the chronic instability is associated with subtalar instability

  7. Comparison of elasticity of human tendon and aponeurosis in knee extensors and ankle plantar flexors in vivo.

    Science.gov (United States)

    Kubo, Keitaro; Kanehisa, Hiroaki; Fukunaga, Tetsuo

    2005-05-01

    The purposes of this study were to compare the elasticity of tendon and aponeurosis in human knee extensors and ankle plantar flexors in vivo and to examine whether the maximal strain of tendon was correlated to that of aponeurosis. The elongation of tendon and aponeurosis during isometric knee extension (n = 23) and ankle plantar flexion (n = 22), respectively, were determined using a real-time ultrasonic apparatus, while the participants performed ramp isometric contractions up to voluntary maximum. To calculate the strain values from the measured elongation, we measured the respective length of tendon and aponeurosis. For the knee extensors, the maximal strain of aponeurosis (12.1 +/- 2.8 %) was significantly greater than that of the patella tendon (8.3 +/- 2.4 %), p aponeurosis in ankle plantar flexors (2.7 +/- 1.4 %), p plantar flexors there was no significant correlation between maximal strain of tendon and aponeurosis. These results would be important for understanding the different roles of tendon and aponeurosis during human movements and for more accurate muscle modeling.

  8. Muscular strategy shift in human running: dependence of running speed on hip and ankle muscle performance.

    Science.gov (United States)

    Dorn, Tim W; Schache, Anthony G; Pandy, Marcus G

    2012-06-01

    Humans run faster by increasing a combination of stride length and stride frequency. In slow and medium-paced running, stride length is increased by exerting larger support forces during ground contact, whereas in fast running and sprinting, stride frequency is increased by swinging the legs more rapidly through the air. Many studies have investigated the mechanics of human running, yet little is known about how the individual leg muscles accelerate the joints and centre of mass during this task. The aim of this study was to describe and explain the synergistic actions of the individual leg muscles over a wide range of running speeds, from slow running to maximal sprinting. Experimental gait data from nine subjects were combined with a detailed computer model of the musculoskeletal system to determine the forces developed by the leg muscles at different running speeds. For speeds up to 7 m s(-1), the ankle plantarflexors, soleus and gastrocnemius, contributed most significantly to vertical support forces and hence increases in stride length. At speeds greater than 7 m s(-1), these muscles shortened at relatively high velocities and had less time to generate the forces needed for support. Thus, above 7 m s(-1), the strategy used to increase running speed shifted to the goal of increasing stride frequency. The hip muscles, primarily the iliopsoas, gluteus maximus and hamstrings, achieved this goal by accelerating the hip and knee joints more vigorously during swing. These findings provide insight into the strategies used by the leg muscles to maximise running performance and have implications for the design of athletic training programs.

  9. Ankle pain

    Science.gov (United States)

    ... which cushions joints) Infection in the ankle joint Osteoarthritis , gout , rheumatoid arthritis , Reiter syndrome , and other types ... Ma, MD, assistant professor, chief, sports medicine and shoulder service, UCSF Department of Orthopaedic Surgery, San Francisco, ...

  10. Design and Characterization of a Quasi-Passive Pneumatic Foot-Ankle Prosthesis.

    Science.gov (United States)

    Lee, Jeffrey D; Mooney, Luke M; Rouse, Elliott J

    2017-07-01

    The majority of commercially available passive prosthetic feet are not capable of providing joint mechanics that match that of the intact human ankle. Due to their cantilever design, their stiffness characteristics contrast with what has been observed in the biological ankle, namely, an increase in stiffness during the stance phase of walking. In this paper, we introduce the design and control of a pneumatic foot-ankle prosthesis that attempts to provide biomimetic mechanics. The prosthesis is comprised of a pneumatic cylinder in series with a fiberglass leaf spring, and a solenoid valve to control the flow of air between the two sides of the cylinder. The solenoid valve acts as a mechanical clutch, enabling resetting of the ankle's equilibrium position. By adjusting the pressure inside the cylinder, the prosthesis can be customized to provide a range of ankle mechanics. A mechanical testing machine is used to compare the torque-angle curve of the pneumatic prosthesis with a low-profile passive prosthetic foot. Finally, data are presented of one transtibial amputee walking with the prosthesis at 1.2 m/s. The testing shows that the pneumatic prosthesis is capable of providing an appropriate range of motion as well a maximum torque of 94 Nm, while returning approximately 11.5 J of energy.

  11. Assessment of Tumor Stiffness With Shear Wave Elastography in a Human Prostate Cancer Xenograft Implantation Model.

    Science.gov (United States)

    Wang, Yiru; Yao, Binwei; Li, Hongfei; Zhang, Yan; Gao, Hanjing; Gao, Yabin; Peng, Ruiyun; Tang, Jie

    2017-05-01

    To investigate the stiffness of human prostate cancer in a xenograft implantation model using shear wave elastography and compare the pathologic features of tumors with varying elasticity. Human prostate cancer DU-145 cells were injected into 24 nude male mice. The mice were divided into 3 groups according to the time of transplantation (6, 8, and 10 weeks). The volume, elasticity, and Young modulus of tumors were recorded by 2-dimensional sonography and shear wave elastography. The tumors were collected for pathologic analyses: hematoxylin-eosin staining, Ponceau S, and aniline staining were used to stain collagen and elastic fibers, and picric acid-sirius red staining was used to indicate type I and III collagen. The area ratios of collagen I/III were calculated. The correlation between the Young modulus of the tumor and area ratio of collagen I/III were evaluated. Immunohistochemistry of vimentin and α-smooth muscle actin was performed. Nineteen tumors in 3 groups were collected. The volume and mean Young modulus increased with the time of transplantation. There were more collagen fibers in the stiff tumors, and there were significant differences in the area ratios of collagen I/III between groups 1 (mean ± SD, 0.50 ± 0.17) and 3 (1.97 ± 0.56; P prostate cancer xenograft implantation tumors. Collagen fibers, especially collagen type I, play a crucial role in the elasticity in the human prostate cancer xenograft implantation model. © 2017 by the American Institute of Ultrasound in Medicine.

  12. Biomechanical Effects of Stiffness in Parallel With the Knee Joint During Walking.

    Science.gov (United States)

    Shamaei, Kamran; Cenciarini, Massimo; Adams, Albert A; Gregorczyk, Karen N; Schiffman, Jeffrey M; Dollar, Aaron M

    2015-10-01

    The human knee behaves similarly to a linear torsional spring during the stance phase of walking with a stiffness referred to as the knee quasi-stiffness. The spring-like behavior of the knee joint led us to hypothesize that we might partially replace the knee joint contribution during stance by utilizing an external spring acting in parallel with the knee joint. We investigated the validity of this hypothesis using a pair of experimental robotic knee exoskeletons that provided an external stiffness in parallel with the knee joints in the stance phase. We conducted a series of experiments involving walking with the exoskeletons with four levels of stiffness, including 0%, 33%, 66%, and 100% of the estimated human knee quasi-stiffness, and a pair of joint-less replicas. The results indicated that the ankle and hip joints tend to retain relatively invariant moment and angle patterns under the effects of the exoskeleton mass, articulation, and stiffness. The results also showed that the knee joint responds in a way such that the moment and quasi-stiffness of the knee complex (knee joint and exoskeleton) remains mostly invariant. A careful analysis of the knee moment profile indicated that the knee moment could fully adapt to the assistive moment; whereas, the knee quasi-stiffness fully adapts to values of the assistive stiffness only up to ∼80%. Above this value, we found biarticular consequences emerge at the hip joint.

  13. Effect of intercostal muscle and costovertebral joint material properties on human ribcage stiffness and kinematics.

    Science.gov (United States)

    Kindig, Matthew; Li, Zuoping; Kent, Richard; Subit, Damien

    2015-01-01

    Current finite element (FE) models of the human thorax are limited by the lack of local-level validation, especially in the ribcage. This study exercised an existing FE ribcage model for a 50th percentile male under quasi-static point loading and dynamic sternal loading. Both force-displacement and kinematic responses of the ribcage were compared against experimental data. The sensitivity of the model response to changes in the material properties of the costovertebral (CV) joints and intercostal muscles was assessed. The simulations found that adjustments to the CV joints tended to change the amount of rib rotation in the sagittal plane, while changes to the elastic modulus and thickness of the intercostal muscles tended to alter both the stiffness and the direction and magnitude of rib motions. This study can lend insight into the role that the material properties of these two thoracic structures play in the dynamics of the ribcage during a frontal loading condition.

  14. Human soleus sarcomere lengths measured using in vivo microendoscopy at two ankle flexion angles.

    Science.gov (United States)

    Chen, Xuefeng; Delp, Scott L

    2016-12-08

    The forces generated by the soleus muscle play an important role in standing and locomotion. The lengths of the sarcomeres of the soleus affect its force-generating capacity, yet it is unknown how sarcomere lengths in the soleus change as a function of ankle flexion angle. In this study, we used microendoscopy to measure resting sarcomere lengths at 10° plantarflexion and 20° dorsiflexion in 7 healthy individuals. Mean sarcomere lengths at 10° plantarflexion were 2.84±0.09µm (mean±S.E.M.), near the optimal length for sarcomere force generation. Sarcomere lengths were 3.43±0.09µm at 20° dorsiflexion, indicating that they were longer than optimal length when the ankle was in dorsiflexion and the muscle was inactive. Our results indicate a smaller sarcomere length difference between two ankle flexion angles compared to estimates from musculoskeletal models and suggest why these models frequently underestimate the force-generating capacity of the soleus.

  15. Predictive Behavior of a Computational Foot/Ankle Model through Artificial Neural Networks

    Science.gov (United States)

    Hargraves, Rosalyn Hobson

    2017-01-01

    Computational models are useful tools to study the biomechanics of human joints. Their predictive performance is heavily dependent on bony anatomy and soft tissue properties. Imaging data provides anatomical requirements while approximate tissue properties are implemented from literature data, when available. We sought to improve the predictive capability of a computational foot/ankle model by optimizing its ligament stiffness inputs using feedforward and radial basis function neural networks. While the former demonstrated better performance than the latter per mean square error, both networks provided reasonable stiffness predictions for implementation into the computational model. PMID:28250804

  16. Predictive Behavior of a Computational Foot/Ankle Model through Artificial Neural Networks.

    Science.gov (United States)

    Chande, Ruchi D; Hargraves, Rosalyn Hobson; Ortiz-Robinson, Norma; Wayne, Jennifer S

    2017-01-01

    Computational models are useful tools to study the biomechanics of human joints. Their predictive performance is heavily dependent on bony anatomy and soft tissue properties. Imaging data provides anatomical requirements while approximate tissue properties are implemented from literature data, when available. We sought to improve the predictive capability of a computational foot/ankle model by optimizing its ligament stiffness inputs using feedforward and radial basis function neural networks. While the former demonstrated better performance than the latter per mean square error, both networks provided reasonable stiffness predictions for implementation into the computational model.

  17. Predictive Behavior of a Computational Foot/Ankle Model through Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    Ruchi D. Chande

    2017-01-01

    Full Text Available Computational models are useful tools to study the biomechanics of human joints. Their predictive performance is heavily dependent on bony anatomy and soft tissue properties. Imaging data provides anatomical requirements while approximate tissue properties are implemented from literature data, when available. We sought to improve the predictive capability of a computational foot/ankle model by optimizing its ligament stiffness inputs using feedforward and radial basis function neural networks. While the former demonstrated better performance than the latter per mean square error, both networks provided reasonable stiffness predictions for implementation into the computational model.

  18. The presence of fructosamine in human aortic valves is associated with valve stiffness.

    Science.gov (United States)

    Kishabongo, Antoine S; Katchunga, Philippe; Cikomola, Justin C; De Somer, Filip M; De Buyzere, Marc L; Speeckaert, Marijn M; Delanghe, Joris R

    2016-09-01

    Human heart valves are prone to glycation, a fundamental process of ageing. The aim of this study was to establish the relationship between fructosamine formation and the mechanical properties of human aortic valves. 67 patients (age: 76±8 years) diagnosed with an aortic valve stenosis, who underwent an aortic valve replacement were enrolled. Fructosamine and calcium concentrations in aortic valves were determined. Using a transthoracic Doppler echocardiography, aortic valve orifice area and transvalvular pressure gradients were measured. In a subgroup of 32 patients, the aortic valve orifice area was sufficient to carry out mechanical testing on a LFPlus Universal material tester. An in vitro removal of fructosamine of the valve was initiated using ATP-dependent fructosamine 3-kinase (FN3K). A significant correlation was found between the aortic valve fructosamine concentration and the calculated aortic valve orifice area: Y (aortic valve orifice area, mm(2))=1.050-0.228X (aortic valve fructosamine concentration, µmol/g valve) (r=-0.38). A significantly higher calcium concentration was measured in the aortic valves of diabetics in comparison with those of non-diabetics. A multiple regression analysis revealed that the presence of diabetes mellitus and aortic valve fructosamine concentration were the main predictors of the extensibility of the aortic valves. In the in vitro deglycation study, a significant lower aortic valve fructosamine concentration was detected after treatment with FN3K. This resulted in an increased flexibility of the aortic valves. Although no direct causativeness is proven with the presented results, which just show an association between fructosamine, the effect of FN3K and aortic valve stiffness, the present study points for the first time towards a possible additional role of the Amadori products in the biomechanical properties of ageing aortic valves. Published by the BMJ Publishing Group Limited. For permission to use (where not

  19. Yes-associated protein regulates the growth of human non-small cell lung cancer in response to matrix stiffness.

    Science.gov (United States)

    Yuan, Yonggang; Zhong, Weiliang; Ma, Ge; Zhang, Baoxiang; Tian, Hui

    2015-06-01

    The Yes‑associated protein (YAP) transcriptional coactivator is recognized as a crucial regulator of human cancer. However, its involvement in human non‑small cell lung cancer (NSCLC) in response to physical cues remains unclear. In this study, substrates with different rigidity were generated in order to evaluate the role of YAP, and its upstream regulators in the Hippo pathway, in the regulation of growth of an NSCLC cell line within particular environments. It was shown that the expression of the YAP protein in SPCA-1 NSCLC cells was significantly increased when cultured on a stiff substrate compared to a soft substrate. However, the expression of phospho‑YAP protein and large tumor suppressor kinase 1 (LATS1) were markedly decreased after culturing on the stiff substrate. Phosphorylation of YAP by LATS1 leads to cytoplasmic retention of YAP, which inhibits its function as a nuclear transcription coactivator. The study also found that the stiff substrate promoted the growth of NSCLC cells in vitro, and an increase in the transcription levels of Survivin, connective tissue growth factor, amphiregulin and Ki67, as well as a decrease in the expression level of YAP in the cytoplasm, and adecrease in p-YAP. In conclusion, the findings showed that the stiffness of the subcellular matrix altered the behavior of NSCLC cells, and that YAP regulated the growth of NSCLC cells in response to matrix stiffness, thereby suggesting a role for the Hippo‑YAP pathway in the response of NSCLC cell growth to specific microenvironments.

  20. Intralimb compensation strategy depends on the nature of joint perturbation in human hopping.

    Science.gov (United States)

    Chang, Young-Hui; Roiz, Ronald A; Auyang, Arick G

    2008-01-01

    Due to the well-described spring-mass dynamics of bouncing gaits, human hopping is a tractable model for elucidating basic neuromuscular compensation principles. We tested whether subjects would employ a multi-joint or single-joint response to stabilize leg stiffness while wearing a spring-loaded ankle-foot orthosis (AFO) that applied localized resistive and assistive torques to the ankle. We analyzed kinematics and kinetics data from nine subjects hopping in place on one leg, at three frequencies (2.2, 2.4, and 2.8Hz) and three orthosis conditions (freely articulating AFO, AFO with plantarflexion resistance, and AFO with plantarflexion assistance). Leg stiffness was invariant across AFO conditions, however, compensation strategy depended upon the nature of the applied load. Biological ankle stiffness increased in response to a resistive load at twice the rate that it decreased with an assitive load. Ankle adjustments alone fully compensated for an assistive load with no net change in combined (biological plus applied) total ankle stiffness (p > or =0.133). In contrast, a resistive load resulted in a 7.4-9.0% increase in total ankle stiffness across frequencies and a concomitant 10-15% increase in knee joint stiffness at each frequency (pcompensation strategies that are specific to the nature of the joint loading.

  1. Long-term use of first-line highly active antiretroviral therapy is not associated with carotid artery stiffness in human immunodeficiency virus-positive patients

    Directory of Open Access Journals (Sweden)

    Haohui Zhu

    2014-09-01

    Full Text Available Objective: To evaluate whether or not highly active antiretroviral therapy is associated with carotid artery stiffness in human immunodeficiency virus-positive patients in Henan Province, China. Method: Fifty human immunodeficiency virus-positive patients with at least a 5-year history of highly active antiretroviral therapy use and 50 human immunodeficiency virus-positive patients without a history of highly active antiretroviral therapy use were enrolled in this study. Carotid artery intima-media thickness and stiffness were determined by quantitative inter-media thickness and quantitative artery stiffness, respectively. Results: No statistically significant difference in carotid artery intima-media thickness and stiffness was observed between groups. A significant association between human immunodeficiency virus infection time and carotid artery stiffness was observed, but no significant association between human immunodeficiency virus infection time and intima-media thickness was found. No significant association between intima-media thickness, stiffness, and CD4+ and CD8+ T-cell counts were observed. Conclusion: The first-line highly active antiretroviral therapy currently used in China is not associated with carotid artery stiffness in human immunodeficiency virus-positive patients with good highly active antiretroviral therapy compliance. Human immunodeficiency virus may play a role in the development of atherosclerosis.

  2. Osteoarthritis of the Foot and Ankle

    Science.gov (United States)

    ... that creates an increased risk of arthritis. Symptoms People with osteoarthritis in the foot or ankle experience, in varying degrees, one or more of the following: Pain and stiffness in the joint Swelling in or near the joint Difficulty walking or bending the joint Some patients with osteoarthritis ...

  3. Optimizing the use of an artificial tongue-placed tactile biofeedback for improving ankle joint position sense in humans.

    Science.gov (United States)

    Vuillerme, N; Chenu, O; Fleury, A; Demongeot, J; Payan, Y

    2006-01-01

    The performance of an artificial tongue-placed tactile biofeedback device for improving ankle joint position sense was assessed in 12 young healthy adults using an active matching task. The underlying principle of this system consisted of supplying individuals with supplementary information about the position of the matching ankle relative to the reference ankle position through a tongue-placed tactile output device generating electrotactile stimulation on a 36- point (6 x 6) matrix held against the surface of the tongue dorsum. Precisely, (1) no electrodes were activated when both ankles were in a similar angular position within predetermined "angular dead zone" (ADZ); (2) 12 electrodes (2 x 6) of the anterior and posterior zones of the matrix were activated (corresponding to the stimulation of the front and rear portion of the tongue) when the matching ankle was in too plantar and dorsiflexed position relative to the reference ankle, respectively. The effects of two ADZ values of 0.5 degrees and 1.5 degrees were evaluated. Results showed (1) more accurate and more consistent matching performances with than without biofeedback and (2) more accurate and more consistent ankle joint matching performances when using the biofeedback device with the smaller ADZ value. These findings suggest that (1) electrotactile stimulation of the tongue can be used to improve ankle joint proprioception and (2) this improvement can be increased through an appropriate specification of the ADZ parameter provided by the biofeedback system. Further investigations are needed to strengthen the potential clinical value of this device.

  4. Effect of follower load on motion and stiffness of the human thoracic spine with intact rib cage.

    Science.gov (United States)

    Sis, Hadley L; Mannen, Erin M; Wong, Benjamin M; Cadel, Eileen S; Bouxsein, Mary L; Anderson, Dennis E; Friis, Elizabeth A

    2016-10-03

    Researchers have reported on the importance of the rib cage in maintaining mechanical stability in the thoracic spine and on the validity of a compressive follower preload. However, dynamic mechanical testing using both the rib cage and follower load has never been studied. An in vitro biomechanical study of human cadaveric thoracic specimens with rib cage intact in lateral bending, flexion/extension, and axial rotation under varying compressive follower preloads was performed. The objective was to characterize the motion and stiffness of the thoracic spine with intact rib cage and follower preload. The hypotheses tested for all modes of bending were (i) range of motion, elastic zone, and neutral zone will be reduced with a follower load, and (ii) neutral and elastic zone stiffness will be increased with a follower load. Eight human cadaveric thoracic spine specimen (T1-T12) with intact rib cage were subjected to 5Nm pure moments in lateral bending, flexion/extension, and axial rotation under follower loads of 0-400N. Range of motion, elastic and neutral zones, and elastic and neutral zone stiffness values were calculated for functional spinal units and segments within the entire thoracic section. Combined segmental range of motion decreased by an average of 34% with follower load for every mode. Application of a follower load with intact rib cage impacts the motion and stiffness of the human cadaveric thoracic spine. Researchers should consider including both aspects to better represent the physiologic implications of human motion and improve clinically relevant biomechanical thoracic spine testing. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Muscle-specific acute changes in passive stiffness of human triceps surae after stretching.

    Science.gov (United States)

    Hirata, Kosuke; Miyamoto-Mikami, Eri; Kanehisa, Hiroaki; Miyamoto, Naokazu

    2016-05-01

    It remains unclear whether the acute effect of stretching on passive muscle stiffness differs among the synergists. We examined the muscle stiffness responses of the medial (MG) and lateral gastrocnemii (LG), and soleus (Sol) during passive dorsiflexion before and after a static stretching by using ultrasound shear wave elastography. Before and after a 5-min static stretching by passive dorsiflexion, shear modulus of the triceps surae and the Achilles tendon (AT) during passive dorsiflexion in the knee extended position were measured in 12 healthy subjects. Before the static stretching, shear modulus was the greatest in MG and smallest in Sol. The stretching induced significant reductions in shear modulus of MG, but not in shear modulus of LG and Sol. The slack angle was observed at more plantar flexed position in the following order: AT, MG, LG, and Sol. After the stretching, the slack angles of each muscle and AT were significantly shifted to more dorsiflexed positions with a similar extent. When considering the shift in slack angle, the change in MG shear modulus became smaller. The present study indicates that passive muscle stiffness differs among the triceps surae, and that the acute effect of a static stretching is observed only in the stiff muscle. However, a large part of the reduction of passive muscle stiffness at a given joint angle could be due to an increase in the slack length.

  6. The role of human ankle plantar flexor muscle-tendon interaction and architecture in maximal vertical jumping examined in vivo.

    Science.gov (United States)

    Farris, Dominic James; Lichtwark, Glen A; Brown, Nicholas A T; Cresswell, Andrew G

    2016-02-01

    Humans utilise elastic tendons of lower limb muscles to store and return energy during walking, running and jumping. Anuran and insect species use skeletal structures and/or dynamics in conjunction with similarly compliant structures to amplify muscle power output during jumping. We sought to examine whether human jumpers use similar mechanisms to aid elastic energy usage in the plantar flexor muscles during maximal vertical jumping. Ten male athletes performed maximal vertical squat jumps. Three-dimensional motion capture and a musculoskeletal model were used to determine lower limb kinematics that were combined with ground reaction force data in an inverse dynamics analysis. B-mode ultrasound imaging of the lateral gastrocnemius (GAS) and soleus (SOL) muscles was used to measure muscle fascicle lengths and pennation angles during jumping. Our results highlighted that both GAS and SOL utilised stretch and recoil of their series elastic elements (SEEs) in a catapult-like fashion, which likely serves to maximise ankle joint power. The resistance of supporting of body weight allowed initial stretch of both GAS and SOL SEEs. A proximal-to-distal sequence of joint moments and decreasing effective mechanical advantage early in the extension phase of the jumping movement were observed. This facilitated a further stretch of the SEE of the biarticular GAS and delayed recoil of the SOL SEE. However, effective mechanical advantage did not increase late in the jump to aid recoil of elastic tissues. © 2016. Published by The Company of Biologists Ltd.

  7. Movement Performance of Human-Robot Cooperation Control Based on EMG-driven Hill-type and Proportional Models for an Ankle Power-assist Exoskeleton Robot.

    Science.gov (United States)

    Ao, Di; Song, Rong; Gao, Jin-Wu

    2016-06-22

    Although the merits of electromyography (EMG)-based control of powered assistive systems have been certified, the factors that affect the performance of EMG-based human-robot cooperation, which are very important, have received little attention. This study investigates whether a more physiologically appropriate model could improve the performance of human-robot cooperation control for an ankle power-assist exoskeleton robot. To achieve the goal, an EMG-driven Hill-type neuromusculoskeletal model (HNM) and a linear proportional model (LPM) were developed and calibrated through maximum isometric voluntary dorsiflexion (MIVD). The two control models could estimate the real-time ankle joint torque, and HNM is more accurate and can account for the change of the joint angle and muscle dynamics. Then, eight healthy volunteers were recruited to wear the ankle exoskeleton robot and complete a series of sinusoidal tracking tasks in the vertical plane. With the various levels of assist based on the two calibrated models, the subjects were instructed to track the target displayed on the screen as accurately as possible by performing ankle dorsiflexion and plantarflexion. Two measurements, the root mean square error (RMSE) and root mean square jerk (RMSJ), were derived from the assistant torque and kinematic signals to characterize the movement performances, whereas the amplitudes of the recorded EMG signals from the tibialis anterior (TA) and the gastrocnemius (GAS) were obtained to reflect the muscular efforts. The results demonstrated that the muscular effort and smoothness of tracking movements decreased with an increase in the assistant ratio. Compared with LPM, subjects made lower physical efforts and generated smoother movements when using HNM, which implied that a more physiologically appropriate model could enable more natural and human-like human-robot cooperation and has potential value for improvement of human-exoskeleton interaction in future applications.

  8. Decrease of contractile properties and transversal stiffness of single fibers in human soleus after 7-day “dry” immersion

    Science.gov (United States)

    Ogneva, I. V.; Ponomareva, E. V.; Kartashkina, N. L.; Altaeva, E. G.; Fokina, N. M.; Kurushin, V. A.; Kozlovskaya, I. B.; Shenkman, B. S.

    2011-05-01

    The simulation model of "dry" immersion was used to evaluate the effects of plantar mechanical stimulation (PMS) and high frequency electromyostimulation (EMS) on the mechanical properties of human soleus fibers under the conditions of gravitational unloading. We examined contractile properties of single fibers by means of tensometry, transversal stiffness of sarcolemma and different areas of the contractile apparatus by means of atomic force microscopy. It was shown that there is a reduction of transversal stiffness in single muscle fibers under hypogravitational conditions. Application of different countermeasures could compensate this effect. Meanwhile pneumostimulation and electro stimulation act in quite different way. Therefore, pneumostimulation seems to be more effective. The data obtained can be considered as the evidence of the fact that such countermeasures as PMS and electromyostimulation influence on muscle fibers in quite different ways and PMS efficiency is likely to be higher. On the basis of our experimental data on transverse stiffness of mechanotransductional nodes and the contractile apparatus, we can assume that support stimulation allows prevention of destructive processes in muscle fibers. Electrostimulation seems to stimulate contractile activity only without suppression of impairment of the fiber mechanical properties.

  9. Total ankle replacement. Early experiences with STAR prosthesis.

    Science.gov (United States)

    Murnaghan, J. M.; Warnock, D. S.; Henderson, S. A.

    2005-01-01

    Early designs of Total Ankle Replacement (TAR) had a high failure rate. More recent experience with the 3-piece, meniscal bearing, total ankle replacement has been more promising. We report a review of the early results of our first 22 prostheses in 20 patients undergoing Scandinavian Total Ankle Replacement (STAR) in Northern Ireland. There was a mean follow-up time of 26 months. Seventeen patients are pain-free at the ankle joint during normal daily activities. Two of the early cases have required revision surgery due to technical errors. Other complications have included malleolar fractures, poor wound healing and postoperative stiffness. These early results show high levels of patient satisfaction, and we are encouraged to continue with total ankle arthroplasty. There is a steep initial learning curve and use of TAR should be restricted to foot and ankle surgeons. Images Fig 1 Figs 2a and b Figs 2 c and d PMID:16022128

  10. Construction of a finite element model of normal human foot and ankle%正常人足踝部有限元模型的构建研究

    Institute of Scientific and Technical Information of China (English)

    刘清华; 余斌; 金丹; 张美超; 胡岩君; 王丹; 罗吉伟

    2010-01-01

    目的 研究足踝部有限元模型的构建方法,为足踝部生物力学提供一个数字化研究平台. 方法 获取一名30岁男性志愿者的右足螺旋CT扫描图像,利用Mimics软件重建出足踝部28块骨骼及外围软组织的三维结构,通过Solidworks处理后导入Ansys的Workebench模块,建立足踝部三维有限元模型.在模型中还通过解剖和文献数据模拟建立各关节软骨、韧带、跖筋膜、小腿骨间膜,然后模拟踝关节正常站立状态下受力,选择相应边界条件进行加载分析. 结果建立了一个包含骨与外围软组织等复合结构的正常人体右足三维有限元模型,相埘客观地反映了人体足踝部的基本解剖结构和力学特性.模拟人体站立状态垂直加载600 N载荷于胫骨下端的上截面,踝关节胫骨下关节面应力主要分布于中部及前外侧,最大应力为3.97 MPa,平均接触应力为1.52 MPa,接触面积为343.6 mm~2. 结论本研究所建立的止常人体足躁部三维有限元模型经验证结果可靠,可进一步用于足踝部损伤的研究.%Objective To report the construction of a finite element (FE) model of normal human foot and ankle which can be used for biomechanical research. Methods Helical CT scan images of a 30-year-old male volunteer's right foot were obtained, The 3D structures of 28 bones and surrounding soft tissues of the foot and ankle were reconstructed with Mimics software. After processed by SolidWorks, the Workebench modules of Ansys were imported to establish a meshed accurate geometrical model of the foot and ankle. The articular cartilages, ligaments, plantar fascias, crural interosseous membranes were also simulated in the model according to anatomic and literature data. The normal standing status of the ankle joint was simulated for loading analysis using appropriate boundary conditions. Results The 3D FE model of normal human right foot complex, including bones and surrounding soft tissues

  11. Optimizing the Use of an Artificial Tongue-Placed Tactile Biofeedback for Improving Ankle Joint Position Sense in Humans

    CERN Document Server

    Vuillerme, N; Fleury, A; Demongeot, J; Payan, Y; Vuillerme, Nicolas; Chenu, Olivier; Fleury, Anthony; Demongeot, Jacques; Payan, Yohan

    2006-01-01

    The performance of an artificial tongue-placed tactile biofeedback device for improving ankle joint position sense was assessed in 12 young healthy adults using an active matching task. The underlying principle of this system consists of supplying individuals with supplementary information about the position of the matching ankle relative to the reference ankle position through a tongue-placed tactile output device generating electrotactile stimulation on a 36-point (6 X 6) matrix held against the surface of the tongue dorsum. Precisely, (1) no electrodes were activated when both ankles were in a similar angular position within a predetermined "angular dead zone" (ADZ); (2) 12 electrodes (2 X 6) of the anterior and posterior zones of the matrix were activated (corresponding to the stimulation of the front and rear portion of the tongue) when the matching ankle was in a too plantarflexed and dorsiflexed position relative to the reference ankle, respectively. Two ADZ values of 0.5° and 1.5° were...

  12. Design of a Simple and Modular 2-DOF Ankle Physiotherapy Device Relying on a Hybrid Serial-Parallel Robotic Architecture

    Directory of Open Access Journals (Sweden)

    Christos E. Syrseloudis

    2011-01-01

    Full Text Available The aim of this work is to propose a new 2-DOF robotic platform with hybrid parallel-serial structure and to undertake its parametric design so that it can follow the whole range of ankle related foot movements. This robot can serve as a human ankle rehabilitation device. The existing ankle rehabilitation devices present typically one or more of the following shortcomings: redundancy, large size, or high cost, hence the need for a device that could offer simplicity, modularity, and low cost of construction and maintenance. In addition, our targeted device must be safe during operation, disallow undesirable movements of the foot, while adaptable to any human foot. Our detailed study of foot kinematics has led us to a new hybrid architecture, which strikes a balance among all aforementioned goals. It consists of a passive serial kinematics chain with two adjustable screws so that the axes of the chain match the two main ankle-axes of typical feet. An active parallel chain, which consists of two prismatic actuators, provides the movement of the platform. Thus, the platform can follow the foot movements, thanks to the passive chain, and also possesses the advantages of parallel robots, including rigidity, high stiffness and force capabilities. The lack of redundancy yields a simpler device with lower size and cost. The paper describes the kinematics modelling of the platform and analyses the force and velocity transmission. The parametric design of the platform is carried out; our simulations confirm the platform's suitability for ankle rehabilitation.

  13. Matrix stiffness regulation of integrin-mediated mechanotransduction during osteogenic differentiation of human mesenchymal stem cells.

    Science.gov (United States)

    Shih, Yu-Ru V; Tseng, Kuo-Fung; Lai, Hsiu-Yu; Lin, Chi-Hung; Lee, Oscar K

    2011-04-01

    Mesenchymal stem cells (MSCs) cultured on extracellular matrices with different stiffness have been shown to possess diverse lineage commitment owing to the extracellular mechanical stimuli sensed by the cells. The aim of this study was to further delineate how matrix stiffness affects intracellular signaling through the mechanotransducers Rho kinase (ROCK) and focal adhesion kinase (FAK) and subsequently regulates the osteogenic phenotype of MSCs. MSCs were cultured in osteogenic medium on tunable polyacrylamide hydrogels coated with type I collagen with elasticities corresponding to Young's modulus of 7.0 ± 1.2 and 42.1 ± 3.2 kPa. Osteogenic differentiation was increased on stiffer matrices, as evident by type I collagen, osteocalcin, and Runx2 gene expressions and alizarin red S staining for mineralization. Western blot analysis demonstrated an increase in kinase activities of ROCK, FAK, and ERK1/2 on stiffer matrices. Inhibition of FAK, an important mediator of osteogenic differentiation, and inhibition of ROCK, a known mechanotransducer of matrix stiffness during osteogenesis, resulted in decreased expression of osteogenic markers during osteogenic induction. In addition, FAK affects osteogenic differentiation through ERK1/2, whereas ROCK regulates both FAK and ERK1/2. Furthermore, α(2)-integrin was upregulated on stiffer matrices during osteogenic induction, and its knockdown by siRNA downregulated the osteogenic phenotype through ROCK, FAK, and ERK1/2. Taken together, our results provide evidence that the matrix rigidity affects the osteogenic outcome of MSCs through mechanotransduction events that are mediated by α(2)-integrin.

  14. Direct influence of culture dimensionality on human mesenchymal stem cell differentiation at various matrix stiffnesses using a fibrous self-assembling peptide hydrogel.

    Science.gov (United States)

    Hogrebe, Nathaniel J; Gooch, Keith J

    2016-09-01

    Much is unknown about the effects of culture dimensionality on cell behavior due to the lack of biomimetic substrates that are suitable for directly comparing cells grown on two-dimensional (2D) and encapsulated within three-dimensional (3D) matrices of the same stiffness and biochemistry. To overcome this limitation, we used a self-assembling peptide hydrogel system that has tunable stiffness and cell-binding site density as well as a fibrous microarchitecture resembling the structure of collagen. We investigated the effect of culture dimensionality on human mesenchymal stem cell differentiation at different values of matrix stiffness (G' = 0.25, 1.25, 5, and 10 kPa) and a constant RGD (Arg-Gly-Asp) binding site concentration. In the presence of the same soluble induction factors, culture on top of stiff gels facilitated the most efficient osteogenesis, while encapsulation within the same stiff gels resulted in a switch to predominantly terminal chondrogenesis. Adipogenesis dominated at soft conditions, and 3D culture induced better adipogenic differentiation than 2D culture at a given stiffness. Interestingly, initial matrix-induced cell morphology was predictive of these end phenotypes. Furthermore, optimal culture conditions corresponded to each cell type's natural niche within the body, highlighting the importance of incorporating native matrix dimensionality and stiffness into tissue engineering strategies. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2356-2368, 2016.

  15. Gallstone disease is associated with arterial stiffness progression.

    Science.gov (United States)

    Yu, Kai-Jing; Zhang, Ji-Rong; Li, Ying; Huang, Xiaoyi; Liu, Tiemin; Li, Chuanfu; Wang, Rui-Tao

    2017-01-01

    Gallstones have been linked to dyslipidemia, metabolic syndrome and cardiovascular disease. Arterial stiffness is an indicator of subclinical atherosclerosis. The aim of this study was to prospectively examine the relationship between gallstone disease and arterial stiffness progression in 347 men and 454 women. These subjects were followed for 7 years. Arterial stiffness progression was measured based on increases in brachial-ankle pulse wave velocity. Changes in brachial-ankle pulse wave velocity during the study period were significantly greater in patients with gallstones than in subjects without gallstones. After adjusting for multiple risk factors, gallstone disease was found to be a significant and independent predictor of brachial-ankle pulse wave velocity progression (β=0.189; Pgallstone disease is an independent predictor of arterial stiffness progression, even after adjusting for other cardiovascular risk factors.

  16. 基于SolidWorks Simulation的人体踝骨力学分析%Mechanics Analysis of the Human Ankle Based on SolidWorks Simulation

    Institute of Scientific and Technical Information of China (English)

    梁松坚; 王维; 王志泳; 刘亚俊

    2013-01-01

    To establish a digital research platform based on SolidWorks Simulation, then model and analyze human being's ankle in conditions of valgus and varus. Mimics10.01 was used for geometric reconstruction of the ankle based on the CT data of the foot. The model was meshed and assigned with the material properties in SolidWorks software, then imported to simulation. And the distortion situation of the ankle was simulated and analyzed in conditions of valgus and varus. The three-dimensional finite element model of the ankle established had good geometric similarity and could do mechanics analysis and measurement. The simulating results were turned out to be feasible. The mechanics simulation analysis of the human ankle based on SolidWorks Simulation is a effective and reliable method. It can improve the understanding of the mechanics mechanism and provide theoretical support for the clinic diagnosis and treatment of related diseases.%建立一个基于SolidWorks Simulation的数字化研究平台,对正常人体足踝在外翻和内翻状况下进行有限元建模与分析。用CT扫描图像提取志愿者骨骼边缘轮廓数据,利用软件Mimics10.01进行图象三维重建,再将足踝各骨的点云文件导入到SolidWorks软件,利用网格处理向导及曲面生成向导建立三维实体模型,并在对模型进行内翻与外翻状态下,用SolidWorks中的插件Simulation对足踝部分发生形变的过程进行模拟分析。建立的足踝三维有限元模型具有较好的几何相似性,能够进行力学分析和测量,模拟分析结果经验证是可行的。基于SolidWorks Simulation的人体踝骨模拟力学分析是个有效可靠的方法,能提高对其力学机制的认识,并为临床相关疾患的诊治提供理论支持。

  17. Position versus force control: using the 2-DOF robotic ankle trainer to assess ankle's motor control.

    Science.gov (United States)

    Farjadian, Amir B; Nabian, Mohsen; Hartman, Amber; Corsino, Johnathan; Mavroidis, Constantinos; Holden, Maureen K

    2014-01-01

    An estimated of 2,000,000 acute ankle sprains occur annually in the United States. Furthermore, ankle disabilities are caused by neurological impairments such as traumatic brain injury, cerebral palsy and stroke. The virtually interfaced robotic ankle and balance trainer (vi-RABT) was introduced as a cost-effective platform-based rehabilitation robot to improve overall ankle/balance strength, mobility and control. The system is equipped with 2 degrees of freedom (2-DOF) controlled actuation along with complete means of angle and torque measurement mechanisms. Vi-RABT was used to assess ankle strength, flexibility and motor control in healthy human subjects, while playing interactive virtual reality games on the screen. The results suggest that in the task with 2-DOF, subjects have better control over ankle's position vs. force.

  18. Assessment of Ankle Injuries

    Science.gov (United States)

    Mai, Nicholas; Cooper, Leslie

    2009-01-01

    School nurses are faced with the challenge of identifying and treating ankle injuries in the school setting. There is little information guiding the assessment and treatment of these children when an injury occurs. It is essential for school nurses to understand ankle anatomy, pathophysiology of the acute ankle injury, general and orthopedic…

  19. Modified Blair ankle fusion for ankle arthritis

    Institute of Scientific and Technical Information of China (English)

    Wang Shuangli; Huang Zhang; Xiong Gaoxin; Chen Guang; Yin Zhongxiang; Jiang Hua

    2014-01-01

    Objective:To investigate the clinical outcome of modified Blair ankle fusion for ankle arthritis.Methods:Between November 2009 and June 2012,28 patients with ankle arthritis were treated,among whom 11 had obvious foot varus deformity,and 17 were almost normal in appearance.There were 13 males and 15 females with an average age of 49.4 years (range,23-67 years).The main symptoms included swelling,pain,and a limited range of motion of the ankles.The ankle joints functions were assessed by American Orthopedic Foot and Ankle Society (AOFAS) ankle and hindfoot score and visual analog scale (VAS) preoperatively and at 1 year follow-up.Results:Twenty-eight patients were followed up for 19.8 months on average (range,1-2 years).Superficial wound infection occurred in 3 cases,and was cured after debridement; the other incisions healed by first intention without complications.All ankles were fused at 1 year follow-up after operation.The symptom was relieved completely in all patients at last follow-up without complication of implant failure,or nonunion.The postoperative AOFAS ankle and hindfoot score was 83.13±3.76,showing significant difference when compared with the preoperative score (45.38±3.21,P<0.01).VAS was significantly decreased from 8.01±0.63 to 2.31±1.05 at 1 year follow-up (P<0.05).Conclusion:Modified Blair ankle fusion has the advantages of high feasiblity,less cost and rigid fixation.It shows high reliability in pain relief and may obtain a good clinical effectiveness.

  20. Identification of stiffness variations in supporting substances of a human canine tooth with a bracket-beam-piezoelectric sensor and its electromechanical impedance

    Directory of Open Access Journals (Sweden)

    Hector A. Tinoco

    2017-06-01

    Full Text Available In this paper, an experimental method is described to identify the stiffness variations produced by drillings done in different supporting substances of a human canine tooth. To measure the supporting substances parameters through of a canine, a sensor-actuator system was developed. The sensor-actuator device was composed of a stainless steel bracket bonded to a steel wire attached to two piezoelectric transducers, with a concentrated mass attached to the end of the wire. To excite the device, high frequency voltage (between 5 and 10 KHz was applied through the piezo-transducers, which affects the tooth by means of the vibration of the wire. High frequency mechanical vibrations allowed the appraisal of the mechanical response from the supporting substances. Mechanical responses associated with the stiffness of the support were quantified with the electrical impedance of the piezo-transducers. The device was coupled to the crown of a canine tooth simulating a condition of fixing as in the bone, the tooth was fastened by the root portion inside the supporting substance. Four supporting substances were characterized for the tests. After establishing base values of the stiffness of each supporting substance, the stiffness variations were assessed in two stages (two drillings; these were made perpendicularly to the longitudinal axis of the tooth, Results show that it is possible to assess stiffness variations with the proposed methodology as well as to quantify the stiffness differences, by means of variation indexes.

  1. Glossary of Foot and Ankle Terms

    Science.gov (United States)

    ... of Charcot fractures in the foot and ankle. Orthopaedics/Orthopedics - The medical and surgical specialty focused on treating, repairing and reconstructing the human musculoskeletal system. Orthopaedist /Orthopaedic Surgeon - A surgeon whose specialty is treating, repairing ...

  2. Pharmacological modulation of arterial stiffness.

    LENUS (Irish Health Repository)

    Boutouyrie, Pierre

    2011-09-10

    Arterial stiffness has emerged as an important marker of cardiovascular risk in various populations and reflects the cumulative effect of cardiovascular risk factors on large arteries, which in turn is modulated by genetic background. Arterial stiffness is determined by the composition of the arterial wall and the arrangement of these components, and can be studied in humans non-invasively. Age and distending pressure are two major factors influencing large artery stiffness. Change in arterial stiffness with drugs is an important endpoint in clinical trials, although evidence for arterial stiffness as a therapeutic target still needs to be confirmed. Drugs that independently affect arterial stiffness include antihypertensive drugs, mostly blockers of the renin-angiotensin-aldosterone system, hormone replacement therapy and some antidiabetic drugs such as glitazones. While the quest continues for \\'de-stiffening drugs\\

  3. Multivariable dynamic ankle mechanical impedance with relaxed muscles.

    Science.gov (United States)

    Lee, Hyunglae; Krebs, Hermano Igo; Hogan, Neville

    2014-11-01

    Neurological or biomechanical disorders may distort ankle mechanical impedance and thereby impair locomotor function. This paper presents a quantitative characterization of multivariable ankle mechanical impedance of young healthy subjects when their muscles were relaxed, to serve as a baseline to compare with pathophysiological ankle properties of biomechanically and/or neurologically impaired patients. Measurements using a highly backdrivable wearable ankle robot combined with multi-input multi-output stochastic system identification methods enabled reliable characterization of ankle mechanical impedance in two degrees-of-freedom (DOFs) simultaneously, the sagittal and frontal planes. The characterization included important ankle properties unavailable from single DOF studies: coupling between DOFs and anisotropy as a function of frequency. Ankle impedance in joint coordinates showed responses largely consistent with a second-order system consisting of inertia, viscosity, and stiffness in both seated (knee flexed) and standing (knee straightened) postures. Stiffness in the sagittal plane was greater than in the frontal plane and furthermore, was greater when standing than when seated, most likely due to the stretch of bi-articular muscles (medial and lateral gastrocnemius). Very low off-diagonal partial coherences implied negligible coupling between dorsiflexion-plantarflexion and inversion-eversion. The directions of principal axes were tilted slightly counterclockwise from the original joint coordinates. The directional variation (anisotropy) of ankle impedance in the 2-D space formed by rotations in the sagittal and frontal planes exhibited a characteristic "peanut" shape, weak in inversion-eversion over a wide range of frequencies from the stiffness dominated region up to the inertia dominated region. Implications for the assessment of neurological and biomechanical impairments are discussed.

  4. Stiff railguns

    Science.gov (United States)

    Weldon, W. F.; Bacon, J. L.; Weeks, D. A.; Zowarka, R. C., Jr.

    1991-01-01

    Stiff guns have been operated with both plasma and solid armatures. A performance gain was seen in the plasma railgun as stiffness was increased. A stiff gun will help to maintain the bore shape and preserve the integrity of the seam between rail and insulator under the extreme asymmetric loads sustained during high-pressure operation. The hydraulically preloaded moly and ceramic gun has been fired six times at pressures as high as 87 ksi, and the bore still holds roughing vacuum up to two hours after the test. The elimination of seam leakage helps control bore erosion associated with plasma reconstitution from the rail and plasma perturbation that might result in loss-initiating instabilities. Reduced rail deflection allows solid and transitioning armatures to track the bore surface. An analysis of the strain energy associated with the deflection of the railgun structure is presented, and this mechanism is found to be a small fraction of the energy associated with armature loss and the rail resistive loss.

  5. Muscle, reflex and central components in the control of the ankle joint in healthy and spastic man.

    Science.gov (United States)

    Sinkjaer, T

    1997-01-01

    In understanding the control of the ankle joint during different motor tasks, we have to investigate at least three components, namely the influence of i) the passive and intrinsic properties of the intact and active muscle system around the joint (termed the non-reflex component), ii) the mechanical importance of the stretch reflex in the stretched and unloaded muscles, and iii) the supraspinal control of the stretch reflex. This thesis is dealing with the importance of the three components in healthy and spastic persons during sitting, standing, and walking. The results are based on stretch reflex and H-reflex measurements from the ankle extensor muscles. During stretch reflex experiments the foot was mounted to a platform (portable during walking) from which the ankle joint torque and the position were measured. To elicit a stretch reflex, the ankle joint was rotated by a strong motor connected to the platform. The mechanical importance of the stretch reflex was investigated by measuring the changes in joint torque. Electrically, the stretch reflex was recorded as the compound muscle action potential through bipolar surface EMG electrodes placed over the soleus muscle. During H-reflex experiments, the tibial nerve was stimulated at the popliteal fossa and the H-reflex recorded over the soleus muscle as during stretch reflex experiments. To investigate how the contractile properties of a muscle in humans depend on the history of activation, we investigated the intrinsic stiffness of the ankle extensors in healthy subjects. At matched background contraction in sitting subjects, a prolonged contraction increased the intrinsic muscle stiffness by 49%. Muscle yielding has been considered especially important for understanding the reflex compensation. We found a general lack of muscle yield and a mechanically important non-reflex stiffness of the ankle extensors showing that non-reflex stiffness is a prominent factor in normal movements of the ankle joint. In both

  6. Association between human immunodeficiency virus infection and arterial stiffness in children

    NARCIS (Netherlands)

    Kuilder, Justin S.; Idris, Nikmah S.; Grobbee, Diederick E.; Bots, Michiel L.; Cheung, Michael M H; Burgner, David; Kurniati, Nia; Uiterwaal, Cuno S P M

    2017-01-01

    Background Human immunodeficiency virus infection (HIV) is associated with increased cardiovascular risk and adverse cardiovascular outcome in adults. Early recognition of changes in vascular properties might prove essential in cardiovascular prevention in HIV-infected patients. We investigated the

  7. Total ankle arthroplasty in end-stage ankle arthritis

    OpenAIRE

    Demetracopoulos, Constantine A.; Halloran, James P.; Maloof, Paul; Samuel B Adams; Parekh, Selene G.

    2013-01-01

    Recent advancements in ankle prosthesis design, combined with improved surgical techniques for correction of coronal plane deformity and ligamentous balancing, have led to a resurgence of interest in total ankle arthroplasty for the treatment of end-stage ankle arthritis. Although ankle arthrodesis has long been considered the gold standard treatment for ankle arthritis, recent studies have shown that patients who undergo total ankle replacement have equivalent pain relief and improved functi...

  8. Posterior ankle impingement.

    Science.gov (United States)

    Giannini, Sandro; Buda, Roberto; Mosca, Massimiliano; Parma, Alessandro; Di Caprio, Francesco

    2013-03-01

    Posterior ankle impingement is a common cause of chronic ankle pain and results from compression of bony or soft tissue structures during ankle plantar flexion. Bony impingement is most commonly related to an os trigonum or prominent trigonal process. Posteromedial soft tissue impingement generally arises from an inversion injury, with compression of the posterior tibiotalar ligament between the medial malleolus and talus. Posterolateral soft tissue impingement is caused by an accessory ligament, the posterior intermalleolar ligament, which spans the posterior ankle between the posterior tibiofibular and posterior talofibular ligaments. Finally, anomalous muscles have also been described as a cause of posterior impingement.

  9. Arterial Stiffness.

    Science.gov (United States)

    Avolio, Alberto

    2013-04-01

    Stiffness of large arteries has been long recognized as a significant determinant of pulse pressure. However, it is only in recent decades, with the accumulation of longitudinal data from large and varied epidemiological studies of morbidity and mortality associated with cardiovascular disease, that it has emerged as an independent predictor of cardiovascular risk. This has generated substantial interest in investigations related to intrinsic causative and associated factors responsible for the alteration of mechanical properties of the arterial wall, with the aim to uncover specific pathways that could be interrogated to prevent or reverse arterial stiffening. Much has been written on the haemodynamic relevance of arterial stiffness in terms of the quantification of pulsatile relationships of blood pressure and flow in conduit arteries. Indeed, much of this early work regarded blood vessels as passive elastic conduits, with the endothelial layer considered as an inactive lining of the lumen and as an interface to flowing blood. However, recent advances in molecular biology and increased technological sophistication for the detection of low concentrations of biochemical compounds have elucidated the highly important regulatory role of the endothelial cell affecting vascular function. These techniques have enabled research into the interaction of the underlying passive mechanical properties of the arterial wall with the active cellular and molecular processes that regulate the local environment of the load-bearing components. This review addresses these emerging concepts.

  10. Impaired gait function in adults with cerebral palsy is associated with reduced rapid force generation and increased passive stiffness

    DEFF Research Database (Denmark)

    Geertsen, Svend Sparre; Kirk, Henrik; Lorentzen, Jakob

    2015-01-01

    analysis of the ankle joint during treadmill walking was obtained by 3-D motion analysis. RESULTS: Passive stiffness was significantly increased in adults with CP compared to controls. Passive stiffness and RFDdf were correlated to reduced toe lift. RFDpf provided the best correlation to push-off velocity...... (mean age 34.3, range 18-57years) and fifteen healthy age-matched controls were biomechanically measured for passive and reflex-mediated stiffness of the ankle plantarflexors at rest, maximal voluntary plantarflexion and dorsiflexion effort (MVCpf,df) and rate of force development (RFDpf,df). Kinematic......, range of movement in the ankle joint and gait speed. Reflex-mediated stiffness was not correlated to any parameters of impaired gait. CONCLUSIONS: Impaired gait function in adults with CP is associated with reduced RFD and increased passive stiffness of ankle muscles. SIGNIFICANCE: These findings...

  11. In situ measurements of human articular cartilage stiffness by means of a scanning force microscope

    Energy Technology Data Exchange (ETDEWEB)

    Imer, Raphael [Institute of Microtechnology, University of Neuchatel, Jaquet-Droz 1, 2007 Neuchatel (Switzerland); Akiyama, Terunobu [Institute of Microtechnology, University of Neuchatel, Jaquet-Droz 1, 2007 Neuchatel (Switzerland); Rooij, Nico F de [Institute of Microtechnology, University of Neuchatel, Jaquet-Droz 1, 2007 Neuchatel (Switzerland); Stolz, Martin [Maurice E. Mueller Institute, University of Basel, Klingelbergstr. 70, 4056 Basel (Switzerland); Aebi, Ueli [Maurice E. Mueller Institute, University of Basel, Klingelbergstr. 70, 4056 Basel (Switzerland); Kilger, Robert [Clinics for Orthopedic Surgery and Traumatology, Kantonsspital, 4101 Bruderholz (Switzerland); Friederich, Niklaus F [Clinics for Orthopedic Surgery and Traumatology, Kantonsspital, 4101 Bruderholz (Switzerland); Wirz, Dieter [Lab. for Orthopaedic Biomechanics, University of Basel, Klingelbergstr. 50-70, 4056 Basel (Switzerland); Daniels, A U [Lab. for Orthopaedic Biomechanics, University of Basel, Klingelbergstr. 50-70, 4056 Basel (Switzerland); Staufer, Urs [Institute of Microtechnology, University of Neuchatel, Jaquet-Droz 1, 2007 Neuchatel (Switzerland)

    2007-03-15

    Osteoarthritis is a painful and disabling progressive joint disease, characterized by degradation of articular cartilage. In order to study this disease at early stages, we have miniaturized and integrated a complete scanning force microscope into a standard arthroscopic device fitting through a standard orthopedic canula. This instrument will allow orthopedic surgeons to measure the mechanical properties of articular cartilage at the nanometer and micrometer scale in-vivo during a standard arthroscopy. An orthopedic surgeon assessed the handling of the instrument. First measurements of the elasticity-modulus of human cartilage were recorded in a cadaver knee non minimal invasive. Second, minimally invasive experiments were performed using arthroscopic instruments. Load-displacement curves were successfully recorded.

  12. The effect of ankle bracing on landing biomechanics in female netballers.

    Science.gov (United States)

    Mason-Mackay, Anna Ruth; Whatman, Chris; Reid, Duncan; Lorimer, Anna

    2016-07-01

    Investigate the impact of lace-up ankle braces on landing biomechanics. Within-subject repeated measures. Participants completed a drop jump, drop land, and netball-specific task in braced and unbraced conditions. Biomechanical research laboratory. Twenty female high school netballers. Leg, knee, and ankle stiffness, knee/ankle stiffness ratio, knee and ankle sagittal excursion, peak vertical ground reaction force, time-to-peak vertical ground reaction force, and loading rate. In the brace condition leg stiffness increased bilaterally during the drop land (ES = 0.21, 0.22), ankle stiffness increased bilaterally during the drop jump (ES = 0.37, 0.29) and drop land (ES = 0.40, 0.60), and knee/ankle stiffness ratio decreased in all three tasks (ES = -0.22 to -0.45). Ankle sagittal excursion decreased bilaterally during the drop jump (ES = -0.35, -0.53) and drop land (ES = -0.23, -0.46), and decreased in the lead limb during the netball jump (ES = -0.36). Knee excursion decreased bilaterally during the drop jump (ES = -0.36, -0.40) and in the lead limb during netball task (ES = -0.59). Lead limb TTP was greater during the netball jump (ES = 0.41). Lace-up ankle braces may increase leg and joint stiffness and reduce joint excursion during landing but do not appear to affect landing forces. The observed effect on landing biomechanics may predispose young netballers to injury. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. The role of series ankle elasticity in bipedal walking.

    Science.gov (United States)

    Zelik, Karl E; Huang, Tzu-Wei P; Adamczyk, Peter G; Kuo, Arthur D

    2014-04-07

    The elastic stretch-shortening cycle of the Achilles tendon during walking can reduce the active work demands on the plantarflexor muscles in series. However, this does not explain why or when this ankle work, whether by muscle or tendon, needs to be performed during gait. We therefore employ a simple bipedal walking model to investigate how ankle work and series elasticity impact economical locomotion. Our model shows that ankle elasticity can use passive dynamics to aid push-off late in single support, redirecting the body's center-of-mass (COM) motion upward. An appropriately timed, elastic push-off helps to reduce dissipative collision losses at contralateral heelstrike, and therefore the positive work needed to offset those losses and power steady walking. Thus, the model demonstrates how elastic ankle work can reduce the total energetic demands of walking, including work required from more proximal knee and hip muscles. We found that the key requirement for using ankle elasticity to achieve economical gait is the proper ratio of ankle stiffness to foot length. Optimal combination of these parameters ensures proper timing of elastic energy release prior to contralateral heelstrike, and sufficient energy storage to redirect the COM velocity. In fact, there exist parameter combinations that theoretically yield collision-free walking, thus requiring zero active work, albeit with relatively high ankle torques. Ankle elasticity also allows the hip to power economical walking by contributing indirectly to push-off. Whether walking is powered by the ankle or hip, ankle elasticity may aid walking economy by reducing collision losses. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Acute effect of static stretching on passive stiffness of the human gastrocnemius fascicle measured by ultrasound shear wave elastography.

    Science.gov (United States)

    Hirata, Kosuke; Kanehisa, Hiroaki; Miyamoto, Naokazu

    2017-03-01

    Passive muscle stiffness and muscle architecture at a given joint angle, as well as slack angle of the muscle have been shown to change after an acute bout of stretching. However, it remains unclear whether passive muscle stiffness at a given fascicle length is reduced after stretching. We aimed to elucidate the acute effect of static stretching on the passive fascicle stiffness using ultrasound shear wave elastography. Shear modulus, fascicle length, and slack angle of the medial gastrocnemius (MG) as well as passive plantar flexion torque during passive dorsiflexion were measured before and after a 5-min static stretching in 14 healthy males. After stretching, passive torques were significantly reduced at >50% of range of motion (ROM). Shear modulus at a given fascicle length was significantly reduced at >80% of the change in fascicle length during passive dorsiflexion. Slack angle of MG was observed at the middle part of ROM and significantly shifted toward more dorsiflexed position after stretching. The present study showed the significant effectiveness of static stretching on the passive fascicle stiffness. Furthermore, the present results suggest that both the shift in slack angle and the reduction in passive fascicle stiffness contribute to produce the change in passive torque-joint angle relationship during passive dorsiflexion. Notably, the contribution of the reduced passive fascicle stiffness to the decrease in passive torque is substantial over the latter part of ROM.

  15. A powered prosthetic ankle joint for walking and running.

    Science.gov (United States)

    Grimmer, Martin; Holgate, Matthew; Holgate, Robert; Boehler, Alexander; Ward, Jeffrey; Hollander, Kevin; Sugar, Thomas; Seyfarth, André

    2016-12-19

    Current prosthetic ankle joints are designed either for walking or for running. In order to mimic the capabilities of an able-bodied, a powered prosthetic ankle for walking and running was designed. A powered system has the potential to reduce the limitations in range of motion and positive work output of passive walking and running feet. To perform the experiments a controller capable of transitions between standing, walking, and running with speed adaptations was developed. In the first case study the system was mounted on an ankle bypass in parallel with the foot of a non-amputee subject. By this method the functionality of hardware and controller was proven. The Walk-Run ankle was capable of mimicking desired torque and angle trajectories in walking and running up to 2.6 m/s. At 4 m/s running, ankle angle could be matched while ankle torque could not. Limited ankle output power resulting from a suboptimal spring stiffness value was identified as a main reason. Further studies have to show to what extent the findings can be transferred to amputees.

  16. Six degree-of-freedom analysis of hip, knee, ankle and foot provides updated understanding of biomechanical work during human walking.

    Science.gov (United States)

    Zelik, Karl E; Takahashi, Kota Z; Sawicki, Gregory S

    2015-03-01

    Measuring biomechanical work performed by humans and other animals is critical for understanding muscle-tendon function, joint-specific contributions and energy-saving mechanisms during locomotion. Inverse dynamics is often employed to estimate joint-level contributions, and deformable body estimates can be used to study work performed by the foot. We recently discovered that these commonly used experimental estimates fail to explain whole-body energy changes observed during human walking. By re-analyzing previously published data, we found that about 25% (8 J) of total positive energy changes of/about the body's center-of-mass and >30% of the energy changes during the Push-off phase of walking were not explained by conventional joint- and segment-level work estimates, exposing a gap in our fundamental understanding of work production during gait. Here, we present a novel Energy-Accounting analysis that integrates various empirical measures of work and energy to elucidate the source of unexplained biomechanical work. We discovered that by extending conventional 3 degree-of-freedom (DOF) inverse dynamics (estimating rotational work about joints) to 6DOF (rotational and translational) analysis of the hip, knee, ankle and foot, we could fully explain the missing positive work. This revealed that Push-off work performed about the hip may be >50% greater than conventionally estimated (9.3 versus 6.0 J, P=0.0002, at 1.4 m s(-1)). Our findings demonstrate that 6DOF analysis (of hip-knee-ankle-foot) better captures energy changes of the body than more conventional 3DOF estimates. These findings refine our fundamental understanding of how work is distributed within the body, which has implications for assistive technology, biomechanical simulations and potentially clinical treatment.

  17. Triceps surae stretch reflex modulation after a mechanically evoked ankle dorsiflexion during the swing phase of human running.

    Science.gov (United States)

    Scohier, Mikael; De Jaeger, Dominique; Schepens, Benedicte

    2014-10-01

    The purpose of this study was to mechanically evoke a triceps surae stretch reflex during the swing phase of running, to study its within-the-step phase dependency. Seven participants ran on a treadmill at 2.8 m·s-1 wearing an exoskeleton capable of evoking a sudden ankle dorsiflexion. We measured the electromyographic activity of the soleus, medial and lateral gastrocnemii just after the perturbation to evaluate the triceps surae stretch reflex. Similar perturbations were also delivered at rest. Our results showed that the stretch reflex was suppressed during the swing phase of running, except in late swing where a late reflex response was observed. At rest, all triceps surae muscles showed an early reflex response to stretch. Our findings suggest that the triceps surae short/medium-latency stretch reflex cannot be evoked during swing phase and thus cannot contribute to the control of the locomotor pattern after aperturbation during this phase.

  18. Design and characterization of a biologically inspired quasi-passive prosthetic ankle-foot.

    Science.gov (United States)

    Mooney, Luke M; Lai, Cara H; Rouse, Elliott J

    2014-01-01

    By design, commonly worn energy storage and release (ESR) prosthetic feet cannot provide biologically realistic ankle joint torque and angle profiles during walking. Additionally, their anthropomorphic, cantilever architecture causes their mechanical stiffness to decrease throughout the stance phase of walking, opposing the known trend of the biological ankle. In this study, the design of a quasi-passive pneumatic ankle-foot prosthesis is detailed that is able to replicate the biological ankle's torque and angle profiles during walking. The prosthetic ankle is comprised of a pneumatic piston, bending spring and solenoid valve. The mechanical properties of the pneumatic ankle prosthesis are characterized using a materials testing machine and the properties are compared to those from a common, passive ESR prosthetic foot. The characterization spanned a range of ankle equilibrium pressures and testing locations beneath the foot, analogous to the location of center of pressure within the stance phase of walking. The pneumatic ankle prosthesis was shown to provide biologically appropriate trends and magnitudes of torque, angle and stiffness behavior, when compared to the passive ESR prosthetic foot. Future work will focus on the development of a control system for the quasi-passive device and clinical testing of the pneumatic ankle to demonstrate efficacy.

  19. Understanding acute ankle ligamentous sprain injury in sports

    Directory of Open Access Journals (Sweden)

    Fong Daniel TP

    2009-07-01

    . Immobilization should not be used as it results in joint stiffness, muscle atrophy and loss of proprioception. Traditional Chinese medicine such as herbs, massage and acupuncture were well applied in China in managing sports injuries, and was reported to be effective in relieving pain, reducing swelling and edema, and restoring normal ankle function. Finally, the best practice of sports medicine would be to prevent the injury. Different previous approaches, including designing prophylactice devices, introducing functional interventions, as well as change of games rules were highlighted. This paper allows the readers to catch up with the previous researches on ankle sprain injury, and facilitate the future research idea on sport-related ankle sprain injury.

  20. Assessing the Relative Contributions of Active Ankle and Knee Assistance to the Walking Mechanics of Transfemoral Amputees Using a Powered Prosthesis.

    Science.gov (United States)

    Ingraham, Kimberly A; Fey, Nicholas P; Simon, Ann M; Hargrove, Levi J

    2016-01-01

    Powered knee-ankle prostheses are capable of providing net-positive mechanical energy to amputees. Yet, there are limitless ways to deliver this energy throughout the gait cycle. It remains largely unknown how different combinations of active knee and ankle assistance affect the walking mechanics of transfemoral amputees. This study assessed the relative contributions of stance phase knee swing initiation, increasing ankle stiffness and powered plantarflexion as three unilateral transfemoral amputees walked overground at their self-selected walking speed. Five combinations of knee and ankle conditions were evaluated regarding the kinematics and kinetics of the amputated and intact legs using repeated measures analyses of variance. We found eliminating active knee swing initiation or powered plantarflexion was linked to increased compensations of the ipsilateral hip joint during the subsequent swing phase. The elimination of knee swing initiation or powered plantarflexion also led to reduced braking ground reaction forces of the amputated and intact legs, and influenced both sagittal and frontal plane loading of the intact knee joint. Gradually increasing prosthetic ankle stiffness influenced the shape of the prosthetic ankle plantarflexion moment, more closely mirroring the intact ankle moment. Increasing ankle stiffness also corresponded to increased prosthetic ankle power generation (despite a similar maximum stiffness value across conditions) and increased braking ground reaction forces of the amputated leg. These findings further our understanding of how to deliver assistance with powered knee-ankle prostheses and the compensations that occur when specific aspects of assistance are added/removed.

  1. Assessing the Relative Contributions of Active Ankle and Knee Assistance to the Walking Mechanics of Transfemoral Amputees Using a Powered Prosthesis

    Science.gov (United States)

    Simon, Ann M.; Hargrove, Levi J.

    2016-01-01

    Powered knee-ankle prostheses are capable of providing net-positive mechanical energy to amputees. Yet, there are limitless ways to deliver this energy throughout the gait cycle. It remains largely unknown how different combinations of active knee and ankle assistance affect the walking mechanics of transfemoral amputees. This study assessed the relative contributions of stance phase knee swing initiation, increasing ankle stiffness and powered plantarflexion as three unilateral transfemoral amputees walked overground at their self-selected walking speed. Five combinations of knee and ankle conditions were evaluated regarding the kinematics and kinetics of the amputated and intact legs using repeated measures analyses of variance. We found eliminating active knee swing initiation or powered plantarflexion was linked to increased compensations of the ipsilateral hip joint during the subsequent swing phase. The elimination of knee swing initiation or powered plantarflexion also led to reduced braking ground reaction forces of the amputated and intact legs, and influenced both sagittal and frontal plane loading of the intact knee joint. Gradually increasing prosthetic ankle stiffness influenced the shape of the prosthetic ankle plantarflexion moment, more closely mirroring the intact ankle moment. Increasing ankle stiffness also corresponded to increased prosthetic ankle power generation (despite a similar maximum stiffness value across conditions) and increased braking ground reaction forces of the amputated leg. These findings further our understanding of how to deliver assistance with powered knee-ankle prostheses and the compensations that occur when specific aspects of assistance are added/removed. PMID:26807889

  2. Assessing the Relative Contributions of Active Ankle and Knee Assistance to the Walking Mechanics of Transfemoral Amputees Using a Powered Prosthesis.

    Directory of Open Access Journals (Sweden)

    Kimberly A Ingraham

    Full Text Available Powered knee-ankle prostheses are capable of providing net-positive mechanical energy to amputees. Yet, there are limitless ways to deliver this energy throughout the gait cycle. It remains largely unknown how different combinations of active knee and ankle assistance affect the walking mechanics of transfemoral amputees. This study assessed the relative contributions of stance phase knee swing initiation, increasing ankle stiffness and powered plantarflexion as three unilateral transfemoral amputees walked overground at their self-selected walking speed. Five combinations of knee and ankle conditions were evaluated regarding the kinematics and kinetics of the amputated and intact legs using repeated measures analyses of variance. We found eliminating active knee swing initiation or powered plantarflexion was linked to increased compensations of the ipsilateral hip joint during the subsequent swing phase. The elimination of knee swing initiation or powered plantarflexion also led to reduced braking ground reaction forces of the amputated and intact legs, and influenced both sagittal and frontal plane loading of the intact knee joint. Gradually increasing prosthetic ankle stiffness influenced the shape of the prosthetic ankle plantarflexion moment, more closely mirroring the intact ankle moment. Increasing ankle stiffness also corresponded to increased prosthetic ankle power generation (despite a similar maximum stiffness value across conditions and increased braking ground reaction forces of the amputated leg. These findings further our understanding of how to deliver assistance with powered knee-ankle prostheses and the compensations that occur when specific aspects of assistance are added/removed.

  3. Control method for exoskeleton ankle with surface electromyography signals

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhen; WANG Zhen; JIANG Jia-xin; QIAN Jin-wu

    2009-01-01

    This paper is concerned with a control method for an exoskeleton ankle with clectromyography (EMG) signals.The EMG signals of human ankle and the exoskeleton ankle are introduced.Then a control method is proposed to control the exoskeleton ankle using the EMG signals.The feed-forward neural network model applied here is composed of four layers and uses the back-propagation training algorithm.The output signals from neural network are processed by the wavelet transform.Finally the control orders generated from the output signals are passed to the motor controller and drive the exoskeleton to move.Through experiments,the equality of neural network prediction of ankle movement is evaluated by giving the correlation coefficient.It is shown from the experimental results that the proposed method can accurately control the movement of ankle joint.

  4. Energetics and passive dynamics of the ankle in downhill walking.

    Science.gov (United States)

    Holm, Jonathan K; Contakos, Jonas; Lee, Sang-Wook; Jang, John

    2010-11-01

    This study investigated the energetics of the human ankle during the stance phase of downhill walking with the goal of modeling ankle behavior with a passive spring and damper mechanism. Kinematic and kinetic data were collected on eight male participants while walking down a ramp with inclination varying from 0° to 8°. The ankle joint moment in the sagittal plane was calculated using inverse dynamics. Mechanical energy injected or dissipated at the ankle joint was computed by integrating the power across the duration of the stance phase. The net mechanical energy of the ankle was approximately zero for level walking and monotonically decreased (i.e., became increasingly negative) during downhill walking as the slope decreased. The indication is that the behavior of the ankle is energetically passive during downhill walking, playing a key role in dissipating energy from one step to the next. A passive mechanical model consisting of a pin joint coupled with a revolute spring and damper was fit to the ankle torque and its parameters were estimated for each downhill slope using linear regression. The passive model demonstrated good agreement with actual ankle dynamics as indicated by low root-mean-square error values. These results indicate the stance phase behavior of the human ankle during downhill walking may be effectively duplicated by a passive mechanism with appropriately selected spring and damping characteristics.

  5. The acute effects of local vibration therapy on ankle sprain and hamstring strain injuries.

    Science.gov (United States)

    Peer, Kimberly S; Barkley, Jacob E; Knapp, Danielle M

    2009-12-01

    The purpose of this study was to determine if biomechanical muscle stimulation (BMS) applied directly to different segments of the body using the Swisswing device results in acute improvements in range of motion and perceived stiffness in physically active adults with acute or subacute ankle sprain and hamstring strain injuries. Two separate groups of individuals with grade I or II ankle sprain (n = 5; 21.2 +/- 1.9 years) or hamstring strain (Nn= 5; 20.6 +/- 1.8 year) underwent 20 minutes of a controlled therapy consisting of ice, compression, and elevation, and 10 minutes of segmental BMS using the Swisswing at 20 Hz. Ankle (dorsiflexion, plantar flexion, inversion, eversion), hamstring flexibility, and subjective ratings of stiffness were assessed prior to control treatment (baseline), post-control treatment, and post-Swisswing treatment. Relative to the post-control condition, Swisswing treatment significantly (P < 0.03 for all) increased ankle dorsiflexion and eversion and hamstring flexibility, and significantly (P ankle and hamstring stiffness. Segmental BMS therapy using the Swisswing device appears to have significant acute benefits for improving flexibility and reducing perceived stiffness in healthy adults with ankle or hamstring injury. Future research is needed to determine the duration of these effects and if repeated periods of segmental BMS therapy aid in long-term injury recovery.

  6. Modified Evans peroneus brevis lateral ankle stabilization for balancing varus ankle contracture during total ankle replacement.

    Science.gov (United States)

    Roukis, Thomas S

    2013-01-01

    Lateral ankle instability is frequently encountered when performing total ankle replacement and remains a challenge. In the present techniques report, I have described a modification of the Evans peroneus brevis tendon lateral ankle stabilization harvested through limited incisions using simple topographic anatomic landmarks. The harvested peroneus brevis is then transferred either to the anterior distal tibia concomitantly with total ankle replacement or through the tibia when performed after total ankle replacement and secured with plate and screw fixation. This modified Evans peroneus brevis tendon is useful in providing lateral ankle stability during or after primary and revision total ankle replacement.

  7. Total Ankle Replacement for Treatment of End-Stage Osteoarthritis in Elderly Patients

    Science.gov (United States)

    Hintermann, Beat; Knupp, Markus; Zwicky, Lukas; Barg, Alexej

    2012-01-01

    End-stage osteoarthritis of the ankle is a disabling problem, particularly in elderly patients who experience an overall loss of mobility and functional impairment and who then need compensatory adaption. Ankle arthrodesis, which has been demonstrated to provide postoperative pain relief and hindfoot stability, leaves the patient with a stiff foot and gait changes. For elderly patient, these changes may be more critical than generally believed. Additionally, the long duration of healing and rehabilitation process needed for ankle arthrodesis may be problematic in the elderly. In contrast to ankle arthrodesis, total ankle replacement has significant advantages including a less strenuous postoperative rehabilitation and preservation of ankle motion which supports physiological gait. Recently, total ankle replacement has evolved as a safe surgical treatment in patients with end-stage ankle osteoarthritis with reliable mid- to long-term results. Total ankle replacement needs less immobilization than arthrodesis and does allow for early weight-bearing and should be considered as a treatment option of first choice in many elderly patients with end-stage osteoarthritis of the ankle, especially in elderly patients with lower expectations and physical demands. PMID:22720158

  8. Total Ankle Replacement for Treatment of End-Stage Osteoarthritis in Elderly Patients

    Directory of Open Access Journals (Sweden)

    Beat Hintermann

    2012-01-01

    Full Text Available End-stage osteoarthritis of the ankle is a disabling problem, particularly in elderly patients who experience an overall loss of mobility and functional impairment and who then need compensatory adaption. Ankle arthrodesis, which has been demonstrated to provide postoperative pain relief and hindfoot stability, leaves the patient with a stiff foot and gait changes. For elderly patient, these changes may be more critical than generally believed. Additionally, the long duration of healing and rehabilitation process needed for ankle arthrodesis may be problematic in the elderly. In contrast to ankle arthrodesis, total ankle replacement has significant advantages including a less strenuous postoperative rehabilitation and preservation of ankle motion which supports physiological gait. Recently, total ankle replacement has evolved as a safe surgical treatment in patients with end-stage ankle osteoarthritis with reliable mid- to long-term results. Total ankle replacement needs less immobilization than arthrodesis and does allow for early weight-bearing and should be considered as a treatment option of first choice in many elderly patients with end-stage osteoarthritis of the ankle, especially in elderly patients with lower expectations and physical demands.

  9. Exercise-induced changes in triceps surae tendon stiffness and muscle strength affect running economy in humans.

    Science.gov (United States)

    Albracht, Kirsten; Arampatzis, Adamantios

    2013-06-01

    The purpose of the present study was to investigate whether increased tendon-aponeurosis stiffness and contractile strength of the triceps surae (TS) muscle-tendon units induced by resistance training would affect running economy. Therefore, an exercise group (EG, n = 13) performed a 14-week exercise program, while the control group (CG, n = 13) did not change their training. Maximum isometric voluntary contractile strength and TS tendon-aponeurosis stiffness, running kinematics and fascicle length of the gastrocnemius medialis (GM) muscle during running were analyzed. Furthermore, running economy was determined by measuring the rate of oxygen consumption at two running velocities (3.0, 3.5 ms(-1)). The intervention resulted in a ∼7 % increase in maximum plantarflexion muscle strength and a ∼16 % increase in TS tendon-aponeurosis stiffness. The EG showed a significant ∼4 % reduction in the rate of oxygen consumption and energy cost, indicating a significant increase in running economy, while the CG showed no changes. Neither kinematics nor fascicle length and elongation of the series-elastic element (SEE) during running were affected by the intervention. The unaffected SEE elongation of the GM during the stance phase of running, in spite of a higher tendon-aponeurosis stiffness, is indicative of greater energy storage and return and a redistribution of muscular output within the lower extremities while running after the intervention, which might explain the improved running economy.

  10. Intraoperative length and tension curves of human eye muscles. Including stiffness in passive horizontal eye movement in awake volunteers

    NARCIS (Netherlands)

    H.J. Simonsz (Huib); G.H. Kolling (Gerold); H. Kaufmann (Herbert); B. van Dijk (Bob)

    1986-01-01

    textabstractIntraoperative continuous-registration length and tension curves of attached and detached eye muscles were made in 18 strabismic patients under general anesthesia. For relaxed eye muscles, we found an exponential relation between length and tension. An increased stiffness was quantified

  11. Effects of safflower seed extract on arterial stiffness

    Directory of Open Access Journals (Sweden)

    Katsuya Suzuki

    2010-11-01

    Full Text Available Katsuya Suzuki1, Shigekazu Tsubaki2, Masami Fujita3, Naoto Koyama1, Michio Takahashi1, Kenji Takazawa41Research Institute for Health Fundamentals, Ajinomoto Co., Inc., Kawasaki; 2Samoncho Clinic, Tokyo; 3Shinanozaka Clinic, Tokyo; 4Tokyo Medical University Hachioji Medical Center, Tokyo, JapanAbstract: Safflower seed extract (SSE contains characteristic polyphenols and serotonin derivatives (N-(p-coumaroyl serotonin and N-feruloylserotonin, which are reported to inhibit oxidation of low-density lipoprotein (LDL, formation of atherosclerotic plaques, and improve arterial stiffness as assessed by pulse wave analysis in animal models. The effects of long-term supplementation with SSE on arterial stiffness in human subjects were evaluated. This double-blind, placebo-controlled study was conducted in 77 males (35–65 years and 15 postmenopausal females (55–65 years with high-normal blood pressure or mild hypertension who were not undergoing treatment. Subjects received SSE (70 mg/day as serotonin derivatives or placebo for 12 weeks, and pulse wave measurements, ie, second derivative of photoplethysmogram (SDPTG, augmentation index, and brachial-ankle pulse wave velocity (baPWV were conducted at baseline, and at weeks 4, 8, and 12. Vascular age estimated by SDPTG aging index improved in the SSE-supplemented group when compared with the placebo group at four (P = 0.0368 and 12 weeks (P = 0.0927. The trend of augmentation index reduction (P = 0.072 versus baseline was observed in the SSE-supplemented group, but reduction of baPWV by SSE supplementation was not observed. The SSE-supplemented group also showed a trend towards a lower malondialdehyde-modified-LDL autoantibody titer at 12 weeks from baseline. These results suggest long-term ingestion of SSE in humans could help to improve arterial stiffness.Keywords: safflower, serotonin derivatives, antioxidants, augmentation index, pulse wave velocity

  12. Stretching human mesenchymal stromal cells on stiffness-customized collagen type I generates a smooth muscle marker profile without growth factor addition

    Science.gov (United States)

    Rothdiener, Miriam; Hegemann, Miriam; Uynuk-Ool, Tatiana; Walters, Brandan; Papugy, Piruntha; Nguyen, Phong; Claus, Valentin; Seeger, Tanja; Stoeckle, Ulrich; Boehme, Karen A.; Aicher, Wilhelm K.; Stegemann, Jan P.; Hart, Melanie L.; Kurz, Bodo; Klein, Gerd; Rolauffs, Bernd

    2016-01-01

    Using matrix elasticity and cyclic stretch have been investigated for inducing mesenchymal stromal cell (MSC) differentiation towards the smooth muscle cell (SMC) lineage but not in combination. We hypothesized that combining lineage-specific stiffness with cyclic stretch would result in a significantly increased expression of SMC markers, compared to non-stretched controls. First, we generated dense collagen type I sheets by mechanically compressing collagen hydrogels. Atomic force microscopy revealed a nanoscale stiffness range known to support myogenic differentiation. Further characterization revealed viscoelasticity and stable biomechanical properties under cyclic stretch with >99% viable adherent human MSC. MSCs on collagen sheets demonstrated a significantly increased mRNA but not protein expression of SMC markers, compared to on culture flasks. However, cyclic stretch of MSCs on collagen sheets significantly increased both mRNA and protein expression of α-smooth muscle actin, transgelin, and calponin versus plastic and non-stretched sheets. Thus, lineage-specific stiffness and cyclic stretch can be applied together for inducing MSC differentiation towards SMCs without the addition of recombinant growth factors or other soluble factors. This represents a novel stimulation method for modulating the phenotype of MSCs towards SMCs that could easily be incorporated into currently available methodologies to obtain a more targeted control of MSC phenotype. PMID:27775041

  13. Stretching human mesenchymal stromal cells on stiffness-customized collagen type I generates a smooth muscle marker profile without growth factor addition

    Science.gov (United States)

    Rothdiener, Miriam; Hegemann, Miriam; Uynuk-Ool, Tatiana; Walters, Brandan; Papugy, Piruntha; Nguyen, Phong; Claus, Valentin; Seeger, Tanja; Stoeckle, Ulrich; Boehme, Karen A.; Aicher, Wilhelm K.; Stegemann, Jan P.; Hart, Melanie L.; Kurz, Bodo; Klein, Gerd; Rolauffs, Bernd

    2016-10-01

    Using matrix elasticity and cyclic stretch have been investigated for inducing mesenchymal stromal cell (MSC) differentiation towards the smooth muscle cell (SMC) lineage but not in combination. We hypothesized that combining lineage-specific stiffness with cyclic stretch would result in a significantly increased expression of SMC markers, compared to non-stretched controls. First, we generated dense collagen type I sheets by mechanically compressing collagen hydrogels. Atomic force microscopy revealed a nanoscale stiffness range known to support myogenic differentiation. Further characterization revealed viscoelasticity and stable biomechanical properties under cyclic stretch with >99% viable adherent human MSC. MSCs on collagen sheets demonstrated a significantly increased mRNA but not protein expression of SMC markers, compared to on culture flasks. However, cyclic stretch of MSCs on collagen sheets significantly increased both mRNA and protein expression of α-smooth muscle actin, transgelin, and calponin versus plastic and non-stretched sheets. Thus, lineage-specific stiffness and cyclic stretch can be applied together for inducing MSC differentiation towards SMCs without the addition of recombinant growth factors or other soluble factors. This represents a novel stimulation method for modulating the phenotype of MSCs towards SMCs that could easily be incorporated into currently available methodologies to obtain a more targeted control of MSC phenotype.

  14. What Is a Foot and Ankle Surgeon?

    Science.gov (United States)

    ... Foot & Ankle Surgeon? A A A | Print | Share What is a Foot & Ankle Surgeon? Foot and ankle ... of conditions that affect people of every age. What education has a foot and ankle surgeon received? ...

  15. Stresses in the ankle joint and total ankle replacement design.

    Science.gov (United States)

    Kakkar, Rahul; Siddique, M S

    2011-06-01

    The ankle is a highly congruent joint with a surface area of 11-13 cm(2). Total ankle replacements have been attempted since the early 1970s and design has continually evolved as the early designs were a failure. This was because the stresses involved and the mutiaxial motion of the ankle has not been understood until recently. It has been shown that the talus slides as well as rolls during the ankle arc of motion from plantarflexion to dorsiflexion. Furthermore, the articular surfaces and the calcaneofibular and tibiocalcaneal ligaments have been shown to form a four bar linkage dictating ankle motion. A new design ankle replacement has been suggested recently which allows multiaxial motion at the ankle while maintaining congruency throughout the arc of motion. The early results of this ankle replacement have been encouraging without any reported failures due to mechanical loosening.

  16. The effect of the oral contraceptive pill on the passive stiffness of the human gastrocnemius muscle in vivo.

    Science.gov (United States)

    Morse, C I; Spencer, J; Hussain, A W; Onambele, G L

    2013-03-01

    The aim of this investigation was to determine the effect of sustained monophasic oral contraceptive pill (MOCP) use on the in vivo passive stiffness of the gastrocnemius medialis (GM) muscle-tendon unit. Twenty four females volunteered for this study (age range 20-25 yrs); twelve participants had been taking the combined MOCP for a minimum of 12 months, and twelve participants, who had never taken the MOCP, formed a control group. Distal displacement of the GM myotendinous junction (MTJ) was measured during passive dorsiflexion at 2 Nm increments to 20 Nm, and at end range of motion using ultrasonography. In addition, GM MTJ displacement was measured at passive torques equivalent to 5, 10 and 15% of plantarflexion maximal voluntary contraction (MVC) torque, and relative to GM length. MOCP users had significantly greater GM MTJ displacement at all passive torques (PMTJ displacement, passive muscle stiffness is less in MOCP using females, compared to non-pill users.

  17. A model of open-loop control of equilibrium position and stiffness of the human elbow joint.

    Science.gov (United States)

    Kistemaker, Dinant A; Van Soest, Arthur J; Bobbert, Maarten F

    2007-03-01

    According to the equilibrium point theory, the control of posture and movement involves the setting of equilibrium joint positions (EP) and the independent modulation of stiffness. One model of EP control, the alpha-model, posits that stable EPs and stiffness are set open-loop, i.e. without the aid of feedback. The purpose of the present study was to explore for the elbow joint the range over which stable EPs can be set open-loop and to investigate the effect of co-contraction on intrinsic low-frequency elbow joint stiffness (K (ilf)). For this purpose, a model of the upper and lower arm was constructed, equipped with Hill-type muscles. At a constant neural input, the isometric force of the contractile element of the muscles depended on both the myofilamentary overlap and the effect of sarcomere length on the sensitivity of myofilaments to [Ca2+] (LDCS). The musculoskeletal model, for which the parameters were chosen carefully on the basis of physiological literature, captured the salient isometric properties of the muscles spanning the elbow joint. It was found that stable open-loop EPs could be achieved over the whole range of motion of the elbow joint and that K (ilf), which ranged from 18 to 42 N m.rad(-1), could be independently controlled. In the model, LDCS contributed substantially to K (ilf) (up to 25 N m.rad(-1)) and caused K (ilf) to peak at a sub-maximal level of co-contraction.

  18. Total Ankle Replacement for Treatment of End-Stage Osteoarthritis in Elderly Patients

    OpenAIRE

    Beat Hintermann; Markus Knupp; Lukas Zwicky; Alexej Barg

    2012-01-01

    End-stage osteoarthritis of the ankle is a disabling problem, particularly in elderly patients who experience an overall loss of mobility and functional impairment and who then need compensatory adaption. Ankle arthrodesis, which has been demonstrated to provide postoperative pain relief and hindfoot stability, leaves the patient with a stiff foot and gait changes. For elderly patient, these changes may be more critical than generally believed. Additionally, the long duration of healing and r...

  19. X-Ray Exam: Ankle

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old X-Ray Exam: Ankle KidsHealth > For Parents > X-Ray Exam: Ankle A A A What's in ... español Radiografía: tobillo What It Is An ankle X-ray is a safe and painless test that ...

  20. Inferring Muscle-Tendon Unit Power from Ankle Joint Power during the Push-Off Phase of Human Walking: Insights from a Multiarticular EMG-Driven Model

    Science.gov (United States)

    2016-01-01

    Introduction Inverse dynamics joint kinetics are often used to infer contributions from underlying groups of muscle-tendon units (MTUs). However, such interpretations are confounded by multiarticular (multi-joint) musculature, which can cause inverse dynamics to over- or under-estimate net MTU power. Misestimation of MTU power could lead to incorrect scientific conclusions, or to empirical estimates that misguide musculoskeletal simulations, assistive device designs, or clinical interventions. The objective of this study was to investigate the degree to which ankle joint power overestimates net plantarflexor MTU power during the Push-off phase of walking, due to the behavior of the flexor digitorum and hallucis longus (FDHL)–multiarticular MTUs crossing the ankle and metatarsophalangeal (toe) joints. Methods We performed a gait analysis study on six healthy participants, recording ground reaction forces, kinematics, and electromyography (EMG). Empirical data were input into an EMG-driven musculoskeletal model to estimate ankle power. This model enabled us to parse contributions from mono- and multi-articular MTUs, and required only one scaling and one time delay factor for each subject and speed, which were solved for based on empirical data. Net plantarflexing MTU power was computed by the model and quantitatively compared to inverse dynamics ankle power. Results The EMG-driven model was able to reproduce inverse dynamics ankle power across a range of gait speeds (R2 ≥ 0.97), while also providing MTU-specific power estimates. We found that FDHL dynamics caused ankle power to slightly overestimate net plantarflexor MTU power, but only by ~2–7%. Conclusions During Push-off, FDHL MTU dynamics do not substantially confound the inference of net plantarflexor MTU power from inverse dynamics ankle power. However, other methodological limitations may cause inverse dynamics to overestimate net MTU power; for instance, due to rigid-body foot assumptions. Moving

  1. Review on design and control aspects of ankle rehabilitation robots.

    Science.gov (United States)

    Jamwal, Prashant K; Hussain, Shahid; Xie, Sheng Q

    2015-03-01

    Ankle rehabilitation robots can play an important role in improving outcomes of the rehabilitation treatment by assisting therapists and patients in number of ways. Consequently, few robot designs have been proposed by researchers which fall under either of the two categories, namely, wearable robots or platform-based robots. This paper presents a review of both kinds of ankle robots along with a brief analysis of their design, actuation and control approaches. While reviewing these designs it was observed that most of them are undesirably inspired by industrial robot designs. Taking note of the design concerns of current ankle robots, few improvements in the ankle robot designs have also been suggested. Conventional position control or force control approaches, being used in the existing ankle robots, have been reviewed. Apparently, opportunities of improvement also exist in the actuation as well as control of ankle robots. Subsequently, a discussion on most recent research in the development of novel actuators and advanced controllers based on appropriate physical and cognitive human-robot interaction has also been included in this review. Implications for Rehabilitation Ankle joint functions are restricted/impaired as a consequence of stroke or injury during sports or otherwise. Robots can help in reinstating functions faster and can also work as tool for recording rehabilitation data useful for further analysis. Evolution of ankle robots with respect to their design and control aspects has been discussed in the present paper and a novel design with futuristic control approach has been proposed.

  2. Establishment and evaluation of finite element model of human foot and ankle%人体足踝部有限元模型的建立及有效性分析

    Institute of Scientific and Technical Information of China (English)

    吴恺; 杨茂伟; 都承斐

    2012-01-01

    背景:传统的足踝部生物力学研究有其局限性,本文介绍一种足踝部有限元建模方法,使其具有高度的几何相似及物理相似.目的:探讨建立足踝部有限元模型的方法,为生物力学研究提供数字化仿真平台.方法:通过CT扫描1名男性志愿者踝关节获取足踝部影像学资料,将其输入Mimics软件重建骨骼和韧带,通过Geomagic处理并生成关节软骨后导入Ansys的Workbench模块,建立足踝部有限元模型,参考相关文献确定材料属性,划分网格,设置边界条件,模拟踝关节正常站立状态下受力,进行加载分析.结果:本研究建立了一个包含骨、软骨及韧带的足踝部有限元模型,相对客观地反映了人体足踝部的基本解剖结构和力学特性.模拟人体站立状态垂直加载600 N载荷于胫、腓骨下端的上截面,踝关节胫骨下关节面的接触应力主要分布在中部及前外侧,最大接触应力为3.74MPa,接触面积为335.5 mm2.踝关节周围四条主要韧带的位移(拉伸长度)中:胫跟韧带>胫舟韧带>跟腓韧带>下胫腓联合前韧带.结论:本研究所建立的人体足踝部有限元模型经验证结果可靠,可进一步用于足踝部生物力学研究.%Background: To redeem the limitations of experimental foot and ankle biomechanics research, the authors describe a new method that makes the finite element model more similar with human foot and ankle in both geometry and physical character. Objective: The purpose of the present study is to explore how to establish finite element model of normal human foot and ankle which can provide a digital simulation platform for biomechanics research. Methods: CT images were obtained by scanning the foot and ankle of a male volunteer Then the data were imported into Mimics software to reconstruct the three-dimensional structure of bones and ligaments. Articular cartilages were established in Geomagic, and the three components of ankle were integrated

  3. Repetitive recombinant human bone morphogenetic protein 2 injections improve the callus microarchitecture and mechanical stiffness in a sheep model of distraction osteogenesis

    Directory of Open Access Journals (Sweden)

    Marc-Frederic Pastor

    2012-03-01

    Full Text Available Evidence suggests that recombinant human bone morphogenetic protein 2 (rhBMP-2 increases the mechanical integrity of callus tissue during bone healing. This effect may be either explained by an increase of callus formation or a modification of the trabecular microarchitecture. Therefore the purpose of the study was to evaluate the potential benefit of rhBMP-2 on the trabecular microarchitecture and on multidirectional callus stiffness. Further we asked, whether microarchitecture changes correlate with optimized callus stiffness. In this study a tibial distraction osteogenesis (DO model in 12 sheep was used to determine, whether percutaneous injection of rhBMP-2 into the distraction zone influences the microarchitecture of the bone regenerate. After a latency period of 4 days, the tibiae were distracted at a rate of 1.25 mm/day over a period of 20 days, resulting in total lengthening of 25 mm. The operated limbs were randomly assigned to one treatment groups and one control group: (A triple injection of rhBMP-2 (4 mg rhBMP-2/injection and (B no injection. The tibiae were harvested after 74 days and scanned by μCT (90 μm/voxel. In addition, we conducted a multidirectional mechanical testing of the tibiae by using a material testing system to assess the multidirectional strength. The distraction zones were tested for torsional stiffness and bending stiffness antero-posterior (AP and medio-lateral (ML direction, compression strength and maximum axial torsion. Statistical analysis was performed using multivariate analysis of variance (ANOVA followed by student’s t-test and Regression analysis using power functions with a significance level of P<0.05. Triple injections of rhBMP-2 induced significant changes in the trabecular architecture of the regenerate compared with the control: increased trabecular number (Tb.N. (treatment group 1.73 mm/1 vs. control group 1.2 mm/1, increased cortical bone volume fraction (BV/TV (treatment group 0.68 vs

  4. Stiffness in the Hand

    Science.gov (United States)

    ... include: Arthritis Fractures Dislocations Bad sprains Tendon and muscle injuries Evaluating Hand Stiffness Your doctor will ask when the stiffness ... scan. CAUSES SIGNS AND ... stretching exercises for the joints and muscles to help loosen them. Different types of splints ...

  5. Method for lower extremity exoskeleton's ankle joint trajectory to track human's in swing phase%在摆动相中用于下肢外骨骼跟踪人体踝关节轨迹的方法

    Institute of Scientific and Technical Information of China (English)

    贾山; 路新亮; 韩亚丽; 王兴松

    2014-01-01

    为实现外骨骼摆动腿踝关节对人体踝关节运动轨迹的跟踪,建立了外骨骼摆动腿逆运动学模型与卡尔曼滤波预测模型,并在外骨骼摆动腿踝关节处设置人机位姿误差传感器,同时进行了人体步态实验。仿真中以实验测取的人体踝关节相对于其髋关节的运动轨迹作为外骨骼踝关节的跟踪对象,并依此计算外骨骼踝关节处人机位姿误差。采用卡尔曼滤波器对外骨骼摆动腿的髋、膝关节位置进行预测,再利用外骨骼逆运动学模型对预测结果进行校正。结果表明:该方法能良好地实现外骨骼摆动腿踝关节对人体踝关节的运动轨迹跟踪,并且卡尔曼滤波预测能明显改善跟踪的滞后性,同时仅需检测外骨骼踝关节处的人机位姿误差也有助于简化人机之间的传感器布置。%To achieve the tracking of the exoskeleton's ankle joint motion trajectory to the human's in the swing phase of a gait,an inverse kinematics model of the exoskeleton's swing leg and a Kal-man filtering prediction model are established.Human-machine posture error sensors are set on the exoskeleton's ankle joints.Meanwhile,human gait experiments are carried out.In the simulation, the trajectory data of the human's ankle joint relative to the hip joint obtained in the experiments are taken as the reference trajectory of the exoskeleton's ankle joint and the calculation basis of the hu-man-machine posture error at the exoskeleton's ankle joint.The Kalman filter is employed to predict the angular positions of the exoskeleton's hip and knee joints.Then,the results of inverse kinematics of the exoskeleton are utilized to correct the prediction.The simulation results indicate that this meth-od can well achieve the tracking of the exoskeleton's ankle joint motion trajectory to the human's in the swing phase of a gait.The Kalman filtering prediction model can significantly decrease the track-ing lag.And the demand

  6. Footballer's ankle: a case report

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    @@ Footballer' s ankle is anterior bony spur or anterior impingement symptom of the ankle with anterior ankle pain, limited and painful dorsiflexion. The cause is commonly seen in athletes and dancers, and is probably due to repetitive minor trauma. The condition was firstly described by Morris;1 McMurray2 reported good results from excision of the spurs, naming it footballer's ankle. Opening resection of osteophytes of the anterior tibial and superior talar is an effective treatment for anterior impingement of the ankle.

  7. Biomechanics of the Ankle-Foot System during Stair Ambulation: Implications for Design of Advanced Ankle-Foot Prostheses

    Science.gov (United States)

    2011-12-15

    effective shape progresses superiorly. After the foot is flat on the step, the effective shape travels superiorly and anteriorly as weight is shifted...During Walking. Ph.D. Thesis. Palmer, M., 2002. Sagittal Plane Charaterization Of Normal Human Ankle Function Across A Range Of Walking Gait Speeds. M.S...human joint motion—part I: ankle, hip, and spine . Journal of Biomechanics 35 (4), 543–548. Yack, H.J., Nielsen, D.H., et al., 1999. Kinetic patterns

  8. Stiff person syndrome.

    Science.gov (United States)

    Ciccoto, Giuseppe; Blaya, Maike; Kelley, Roger E

    2013-02-01

    Recognizing stiff person syndrome is clinically important. It is uncommon, characterized by body stiffness associated with painful muscle spasms, and varies in location and severity. It is subdivided into stiff trunk versus stiff limb presentation, and as a progressive encephalomyelitis. Stiff person-type syndrome also reflects a paraneoplastic picture. Most patients demonstrate exaggerated lumbar lordosis. Roughly 60% of patients have antiglutamic acid decarboxylase antibodies in the blood and the cerebrospinal fluid. The differential diagnosis includes many severe conditions. There are reports of response to muscle relaxants, immunosuppressants, intravenous gamma globulin, plasma exchange, a number of anticonvulsants, and botulinum toxin.

  9. The Effect of High Dose Cholecalciferol on Arterial Stiffness and Peripheral and Central Blood Pressure in Healthy Humans

    DEFF Research Database (Denmark)

    Bressendorff, Iain; Brandi, Lisbet; Schou, Morten

    2016-01-01

    and blood pressure in healthy normotensive adults. METHODS: 40 healthy adults were randomised in this double-blinded study to either oral cholecalciferol 3000 IU/day or matching placebo and were followed for 16 weeks to examine any effects on pulse wave velocity (PWV), augmentation index (AIx), peripheral...... and central blood pressure and 24-hour ambulatory blood pressure. RESULTS: 22 subjects in the cholecalciferol arm and 18 subjects in the placebo arm completed the 16 weeks of follow-up. There was no difference in changes in PWV, AIx corrected for heart rate or central or peripheral blood pressure between...... the two groups. There was no correlation between serum 25-hydroxy vitamin D and any of these parameters. CONCLUSIONS: Oral cholecalciferol 3000 IU/day does not affect arterial stiffness or blood pressure after 16 weeks of treatment in healthy normotensive adults. TRIAL REGISTRATION: ClinicalTrials.gov NCT...

  10. Improvement in gait following combined ankle and subtalar arthrodesis.

    Science.gov (United States)

    Tenenbaum, Shay; Coleman, Scott C; Brodsky, James W

    2014-11-19

    affected limb postoperatively. There were marked increases in gait velocity, ankle moment, and hip motion and power, documenting objective improvements in ambulatory function. The data showed that preoperative ankle motion was greatly diminished. This may suggest that pain is more important than stiffness in asymmetric gait. Copyright © 2014 by The Journal of Bone and Joint Surgery, Incorporated.

  11. Convergence of ipsi- and contralateral muscle afferents on common interneurons mediating reciprocal inhibition of ankle plantarflexors in humans

    DEFF Research Database (Denmark)

    Mrachacz-Kersting, Natalie; Geertsen, Svend Sparre; Stevenson, Andrew James Thomas

    2017-01-01

    reciprocal Ia inhibition of the opposite limb. This study was designed to investigate whether this pathway is similar in humans to that described in animals. Thirteen healthy volunteers participated in one of two experiments. In experiment 1, the effects of ipsilateral posterior tibial nerve (i......CPN stimulation were delivered separately or in combination and changes in the ongoing electromyography (EMG) quantified. In experiment 2, the amplitude of a test SOL H-reflex elicited by contralateral PTN (cPTN) stimulation was quantified following iPTN, cCPN or iPTN + cCPN nerve stimulation (n = 5). Intensities...... used during the H-reflex conditioning experiment were 1.79 ± 0.4 × MT for the iPTN stimulation and 0.88 ± 0.16 × MT for cCPN stimulation. Across all participants, the onset of the cSOL EMG suppression was 42 ± 4, 44 ± 3 and 44 ± 3 ms for iPTN, cCPN and iPTN + cCPN conditions, respectively...

  12. Intra-articular Pressure Based Stress Analysis of the Distal Tibia Following Insertion of a Total Ankle Replacement

    OpenAIRE

    Soodmand, Ehsan; Natsakis, Tassos; Jonkers, Ilse; Vander Sloten, Jos

    2015-01-01

    The ankle joint plays an important role in transferring the human body weight to the ground. Given the associated loading, Osteoarthritis (OA) is one of the most common disorders in the ankle joint. The most common treatment of ankle OA is total ankle arthroplasty (TAA). However it is not known whether TAA influences the stress levels of the bone structures and specially the distal tibia. Clinical studies previously related the occurrence of tibia cysts to focal stress concentrations. In this...

  13. American Orthopaedic Foot and Ankle Society

    Science.gov (United States)

    ... Statements Publications Foot & Ankle International (FAI) Foot & Ankle Orthopaedics (FAO) In~Stride Newsletter News Center Press Releases ... the best possible care, see a foot & ankle ORTHOPAEDIC surgeon. Find one in your area here. Having ...

  14. A Novel Index Using Ankle Hemodynamic Parameters to Assess the Severity of Peripheral Arterial Disease: A Pilot Study

    Science.gov (United States)

    Tanno, Jun; Gatate, Yodo; Kasai, Takatoshi; Nakano, Shintaro; Senbonmatsu, Takaaki; Sato, Osamu; Ichioka, Shigeru; Kuro-o, Makoto; Nishimura, Shigeyuki

    2016-01-01

    In peripheral arterial disease (PAD) of the lower extremities, the presence of flow-limiting stenoses can be objectively detected by the ankle-brachial index (ABI). However, the severity of ischemic symptoms is not necessarily associated with the ABI value. Atherosclerotic plaque in lower extremity PAD induces ankle arterial stiffness and reduces ankle vascular resistance, which may decrease ankle blood flow and cause ischemic symptoms. We hypothesized that the ankle hemodynamic index (AHI), defined as the ratio of ankle arterial stiffness to ankle vascular resistance, could be used to assess the blood supply deficiency in a diseased lower limb in patients with PAD. The 85 consecutive patients with PAD who were retrospectively analyzed in this study had Rutherford grade 1 to grade 6 ischemia diagnosed as PAD and significant stenotic lesions (>50% diameter stenosis) of the lower extremity on contrast angiography. The AHI was calculated as the product of the ankle pulse pressure and the ratio of heart rate to ankle mean arterial pressure (ankle pulse pressure × heart rate/ankle mean arterial pressure). The Rutherford grade was significantly correlated with the AHI (r = 0.50, P < 0.001), but not with the ABI (r = 0.07, P = 0.52). Multiple ordinal regression analysis showed that anemia (odds ratio 0.66, P = 0.002) and AHI (odds ratio 1.04, P = 0.02) were independently associated with Rutherford grade. Our study shows that AHI, a novel parameter based on the ABI measurement, is well correlated with ischemic symptoms, and may be a useful means to assess the arterial blood supply of the lower extremities of patients with PAD. PMID:27760183

  15. Estimating Gear Teeth Stiffness

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard

    2013-01-01

    The estimation of gear stiffness is important for determining the load distribution between the gear teeth when two sets of teeth are in contact. Two factors have a major influence on the stiffness; firstly the boundary condition through the gear rim size included in the stiffness calculation...... and secondly the size of the contact. In the FE calculation the true gear tooth root profile is applied. The meshing stiffness’s of gears are highly non-linear, it is however found that the stiffness of an individual tooth can be expressed in a linear form assuming that the contact length is constant....

  16. Stiffness of compression devices

    Directory of Open Access Journals (Sweden)

    Giovanni Mosti

    2013-03-01

    Full Text Available This issue of Veins and Lymphatics collects papers coming from the International Compression Club (ICC Meeting on Stiffness of Compression Devices, which took place in Vienna on May 2012. Several studies have demonstrated that the stiffness of compression products plays a major role for their hemodynamic efficacy. According to the European Committee for Standardization (CEN, stiffness is defined as the pressure increase produced by medical compression hosiery (MCH per 1 cm of increase in leg circumference.1 In other words stiffness could be defined as the ability of the bandage/stockings to oppose the muscle expansion during contraction.

  17. Idiopathic toe-walking in children, adolescents and young adults: a matter of local or generalised stiffness?

    Directory of Open Access Journals (Sweden)

    van de Putte Elise

    2011-03-01

    Full Text Available Abstract Background Idiopathic Toe Walking (ITW is present in children older than 3 years of age still walking on their toes without signs of neurological, orthopaedic or psychiatric diseases. ITW has been estimated to occur in 7% to 24% of the childhood population. To study associations between Idiopathic Toe Walking (ITW and decrease in range of joint motion of the ankle joint. To study associations between ITW (with stiff ankles and stiffness in other joints, muscle strength and bone density. Methods In a cross-sectional study, 362 healthy children, adolescents and young adults (mean age (sd: 14.2 (3.9 years participated. Range of joint motion (ROM, muscle strength, anthropometrics sport activities and bone density were measured. Results A prevalence of 12% of ITW was found. Nine percent had ITW and severely restricted ROM of the ankle joint. Children with ITW had three times higher chance of severe ROM restriction of the ankle joint. Participants with ITW and stiff ankle joints had a decreased ROM in other joints, whereas bone density and muscle strength were comparable. Conclusion ITW and a decrease in ankle joint ROM might be due to local stiffness. Differential etiological diagnosis should be considered.

  18. Contributions of knee swing initiation and ankle plantar flexion to the walking mechanics of amputees using a powered prosthesis.

    Science.gov (United States)

    Ingraham, Kimberly A; Fey, Nicholas P; Simon, Ann M; Hargrove, Levi J

    2014-01-01

    Recently developed powered prostheses are capable of producing near-physiological joint torque at the knee and/or ankle joints. Based on previous studies of biological joint impedance and the mechanics of able-bodied gait, an impedance-based controller has been developed for a powered knee and ankle prosthesis that integrates knee swing initiation and powered plantar flexion in late stance with increasing ankle stiffness throughout stance. In this study, five prosthesis configuration conditions were tested to investigate the individual contributions of each sub-strategy to the overall walking mechanics of four unilateral transfemoral amputees as they completed a clinical 10-m walk test using a powered knee and ankle prosthesis. The baseline condition featured constant ankle stiffness and no swing initiation or powered plantar flexion. The four remaining conditions featured knee swing initiation alone (SI) or in combination with powered plantar flexion (SI+PF), increasing ankle stiffness (SI+IK), or both (SI+PF+IK). Self-selected walking speed did not significantly change between conditions, although subjects tended to walk the slowest in the baseline condition compared to conditions with swing initiation. The addition of powered plantar flexion resulted in significantly higher ankle power generation in late stance irrespective of ankle stiffness. The inclusion of swing initiation resulted in a significantly more flexed knee at toe off and a significantly higher average extensor knee torque following toe off. Identifying individual contributions of intrinsic control strategies to prosthesis biomechanics could help inform the refinement of impedance-based prosthesis controllers and simplify future designs of prostheses and lower-limb assistive devices alike.

  19. Association of Inflammatory Gene Polymorphisms and Conventional Risk Factors With Arterial Stiffness by Age

    OpenAIRE

    ,

    2013-01-01

    Background Inflammatory gene polymorphisms are potentially associated with atherosclerosis risk, but their age-related effects are unclear. To investigate the age-related effects of inflammatory gene polymorphisms on arterial stiffness, we conducted cross-sectional and 5-year follow-up studies using the cardio-ankle vascular index (CAVI) as a surrogate marker of arterial stiffness. Methods We recruited 1850 adults aged 34 to 69 years from the Japanese general population. Inflammatory gene pol...

  20. Increased unilateral tendon stiffness and its effect on gait 2-6 years after Achilles tendon rupture.

    Science.gov (United States)

    Agres, A N; Duda, G N; Gehlen, T J; Arampatzis, A; Taylor, W R; Manegold, S

    2015-12-01

    Achilles tendon rupture (ATR) alters tissue composition, which may affect long-term tendon mechanics and ankle function during movement. However, a relationship between Achilles tendon (AT) properties and ankle joint function during gait remains unclear. The primary hypotheses were that (a) post-ATR tendon stiffness and length differ from the noninjured contralateral side and that (b) intra-patient asymmetries in AT properties correlate to ankle function asymmetries during gait, determined by ankle angles and moments. Ultrasonography and dynamometry were used to assess AT tendon stiffness, strain, elongation, and rest length in both limbs of 20 ATR patients 2-6 years after repair. Three-dimensional ankle angles and moments were determined using gait analysis. Injured tendons exhibited increased stiffness, rest length, and altered kinematics, with higher dorsiflexion and eversion, and lower plantarflexion and inversion. Intra-patient tendon stiffness and tendon length ratios were negatively correlated to intra-patient ratios of the maximum plantarflexion moment and maximum dorsiflexion angle, respectively. These results suggest that after surgical ATR repair, higher AT stiffness, but not a longer AT, may contribute to deficits in plantarflexion moment generation. These data further support the claim that post-ATR tendon regeneration results in the production of a tissue that is functionally different than noninjured tendon. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Biomaterial arrays with defined adhesion ligand densities and matrix stiffness identify distinct phenotypes for tumorigenic and nontumorigenic human mesenchymal cell types.

    Science.gov (United States)

    Hansen, Tyler D; Koepsel, Justin T; Le, Ngoc Nhi; Nguyen, Eric H; Zorn, Stefan; Parlato, Matthew; Loveland, Samuel G; Schwartz, Michael P; Murphy, William L

    2014-05-01

    Here, we aimed to investigate migration of a model tumor cell line (HT-1080 fibrosarcoma cells, HT-1080s) using synthetic biomaterials to systematically vary peptide ligand density and substrate stiffness. A range of substrate elastic moduli were investigated by using poly(ethylene glycol) (PEG) hydrogel arrays (0.34 - 17 kPa) and self-assembled monolayer (SAM) arrays (~0.1-1 GPa), while cell adhesion was tuned by varying the presentation of Arg-Gly-Asp (RGD)-containing peptides. HT-1080 motility was insensitive to cell adhesion ligand density on RGD-SAMs, as they migrated with similar speed and directionality for a wide range of RGD densities (0.2-5% mol fraction RGD). Similarly, HT-1080 migration speed was weakly dependent on adhesion on 0.34 kPa PEG surfaces. On 13 kPa surfaces, a sharp initial increase in cell speed was observed at low RGD concentration, with no further changes observed as RGD concentration was increased further. An increase in cell speed ~ two-fold for the 13 kPa relative to the 0.34 kPa PEG surface suggested an important role for substrate stiffness in mediating motility, which was confirmed for HT-1080s migrating on variable modulus PEG hydrogels with constant RGD concentration. Notably, despite ~ two-fold changes in cell speed over a wide range of moduli, HT-1080s adopted rounded morphologies on all surfaces investigated, which contrasted with well spread primary human mesenchymal stem cells (hMSCs). Taken together, our results demonstrate that HT-1080s are morphologically distinct from primary mesenchymal cells (hMSCs) and migrate with minimal dependence on cell adhesion for surfaces within a wide range of moduli, whereas motility is strongly influenced by matrix mechanical properties.

  2. Novel Rho/MRTF/SRF Inhibitors Block Matrix-stiffness and TGF-β–Induced Fibrogenesis in Human Colonic Myofibroblasts

    Science.gov (United States)

    Johnson, Laura A.; Rodansky, Eva S.; Haak, Andrew J.; Larsen, Scott D.; Neubig, Richard R.; Higgins, Peter D. R.

    2016-01-01

    Background Ras homolog gene family, member A (RhoA)/Rho-associated coiled-coil forming protein kinase signaling is a key pathway in multiple types of solid organ fibrosis, including intestinal fibrosis. However, the pleiotropic effects of RhoA/Rho-associated coiled-coil forming protein kinase signaling have frustrated targeted drug discovery efforts. Recent recognition of the role of Rho-regulated gene transcription by serum response factor (SRF) and its transcriptional cofactor myocardin-related transcription factor A (MRTF-A) suggest a novel locus for pharmacological intervention. Methods Because RhoA signaling is mediated by both physical and biochemical stimuli, we examined whether pharmacological inhibition of RhoA or the downstream transcription pathway of MRTF-A/SRF could block intestinal fibrogenesis in 2 in vitro models. Results In this study, we demonstrate that inhibition of RhoA signaling blocks both matrix-stiffness and transforming growth factor beta–induced fibrogenesis in human colonic myofibroblasts. Repression of alpha-smooth muscle actin and collagen expression was associated with the inhibition of MRTF-A nuclear localization. CCG-1423, a first-generation Rho/MRTF/SRF pathway inhibitor, repressed fibrogenesis in both models, yet has unacceptable cytotoxicity. Novel second-generation inhibitors (CCG-100602 and CCG-203971) repressed both matrix-stiffness and transforming growth factor beta–mediated fibrogenesis as determined by protein and gene expression in a dose-dependent manner. Conclusions Targeting the Rho/MRTF/SRF mechanism with second-generation Rho/MRTF/SRF inhibitors may represent a novel approach to antifibrotic therapeutics. PMID:24280883

  3. Enzymatically cross-linked gelatin-phenol hydrogels with a broader stiffness range for osteogenic differentiation of human mesenchymal stem cells.

    Science.gov (United States)

    Wang, Li-Shan; Du, Chan; Chung, Joo Eun; Kurisawa, Motoichi

    2012-05-01

    An injectable hydrogel system, composed of gelatin-hydroxyphenylpropionic acid (Gtn-HPA) conjugates chemically cross-linked by an enzyme-mediated oxidation reaction, has been designed as a biodegradable scaffold for tissue engineering. In light of the role of substrate stiffness on cell differentiation, we herein report a newly improved Gtn hydrogel system with a broader range of stiffness control that uses Gtn-HPA-tyramine (Gtn-HPA-Tyr) conjugates to stimulate the osteogenic differentiation of human mesenchymal stem cells (hMSCs). The Gtn-HPA-Tyr conjugate was successfully synthesized through a further conjugation of Tyr to Gtn-HPA conjugate by means of a general carbodiimide/active ester-mediated coupling reaction. Proton nuclear magnetic resonance and UV-visible measurements showed a higher total phenol content in the Gtn-HPA-Tyr conjugate than that content in the Gtn-HPA conjugate. The Gtn-HPA-Tyr hydrogels were formed by the oxidative coupling of phenol moieties catalyzed by hydrogen peroxide (H(2)O(2)) and horseradish peroxidase (HRP). Rheological studies revealed that a broader range of storage modulus (G') of Gtn-HPA-Tyr hydrogel (600-26,800 Pa) was achieved using different concentrations of H(2)O(2), while the G' of the predecessor Gtn-HPA hydrogels was limited to the range of 1000 to 13,500 Pa. The hMSCs on Gtn-HPA-Tyr hydrogel with G' greater than 20,000 showed significantly up-regulated expressions of osteocalcin and runt-related transcription factor 2 (RUNX2) on both the gene and protein level, with the presence of alkaline phosphatase, and the evidence of calcium accumulation. These studies with the Gtn-HPA-Tyr hydrogel with G' greater than 20,000 collectively suggest the stimulation of the hMSCs into osteogenic differentiation, while these same observations were not found with the Gtn-HPA hydrogel with a G' of 13,500.

  4. Crosslinking by advanced glycation end products increases the stiffness of the collagen network in human articular cartilage: A possible mechanism through which age is a risk factor for osteoarthritis

    NARCIS (Netherlands)

    Verzijl, N.; Groot, J. de; Zaken, C.B.; Braun-Benjamin, O.; Maroudas, A.; Bank, R.A.; Mizrahi, J.; Schalkwijk, C.G.; Thorpe, S.R.; Baynes, J.W.; Bijlsma, J.W.J.; Lafeber, F.P.J.G.; TeKoppele, J.M.

    2002-01-01

    Objective. Age is an important risk factor for osteoarthritis (OA). During aging, nonenzymatic glycation results in the accumulation of advanced glycation end products (AGEs) in cartilage collagen. We studied the effect of AGE crosslinking on the stiffness of the collagen network in human articular

  5. Crosslinking by advanced glycation end products increases the stiffness of the collagen network in human articular cartilage: A possible mechanism through which age is a risk factor for osteoarthritis

    NARCIS (Netherlands)

    Verzijl, N.; Groot, J. de; Zaken, C.B.; Braun-Benjamin, O.; Maroudas, A.; Bank, R.A.; Mizrahi, J.; Schalkwijk, C.G.; Thorpe, S.R.; Baynes, J.W.; Bijlsma, J.W.J.; Lafeber, F.P.J.G.; TeKoppele, J.M.

    2002-01-01

    Objective. Age is an important risk factor for osteoarthritis (OA). During aging, nonenzymatic glycation results in the accumulation of advanced glycation end products (AGEs) in cartilage collagen. We studied the effect of AGE crosslinking on the stiffness of the collagen network in human articular

  6. Total ankle replacement or ankle fusion in painful advanced hemophilic arthropathy of the ankle.

    Science.gov (United States)

    Rodriguez-Merchan, E Carlos

    2015-12-01

    In advanced painful hemophilic arthropathy of the ankle, the last resort is surgical treatment (ankle arthrodesis [AA] or total ankle replacement [TAR]). There is a controversy in the literature on which of the two procedures is more appropriate. A review of the literature was performed to clarify such a controversy. The first search engine was MedLine (keywords: total ankle replacement, ankle arthrodesis). Seventy articles were found in MedLine. Of these, only 16 were selected and reviewed because they were strictly focused on the topic of this article. The second search engine was the Cochrane Library, where only nine systematic reviews were found on the role of TAR and AA in non-hemophilia patients. TAR and AA provide pain relief and patient satisfaction in hemophilia patients in the short term. The available non-hemophilia literature is insufficient to conclude which treatment is superior. My current view is that AA may be preferable in most hemophilia patients.

  7. Reverse Evans peroneus brevis medial ankle stabilization for balancing valgus ankle contracture during total ankle replacement.

    Science.gov (United States)

    Roukis, Thomas S; Prissel, Mark A

    2014-01-01

    Medial ankle instability secondary to deltoid ligament insufficiency is frequently encountered when performing total ankle replacement and remains a challenge. In the present techniques report, we describe a "reverse" Evans peroneus brevis tendon nonanatomic deltoid ligament reconstruction for medial ankle stabilization harvested through limited incisions using simple topographic anatomic landmarks. The harvested peroneus brevis tendon is brought through a drill hole in the talus from laterally to medially, aiming for the junction of the talar neck and body plantar to the midline. The tendon is the brought superiorly and obliquely to the anterior medial aspect of the distal tibia where it is secured under a plate and screw construct. This modified Evans peroneus brevis tendon nonanatomic deltoid ligament reconstruction is useful in providing medial ankle stability during or after primary and revision total ankle replacement.

  8. A decreased level of serum soluble Klotho is an independent biomarker associated with arterial stiffness in patients with chronic kidney disease.

    Directory of Open Access Journals (Sweden)

    Masashi Kitagawa

    Full Text Available BACKGROUND: Klotho was originally identified in a mutant mouse strain unable to express the gene that consequently showed shortened life spans. In humans, low serum Klotho levels are related to the prevalence of cardiovascular diseases in community-dwelling adults. However, it is unclear whether the serum Klotho levels are associated with signs of vascular dysfunction such as arterial stiffness, a major determinant of prognosis, in human subjects with chronic kidney disease (CKD. METHODS: We determined the levels of serum soluble Klotho in 114 patients with CKD using ELISA and investigated the relationship between the level of Klotho and markers of CKD-mineral and bone disorder (CKD-MBD and various types of vascular dysfunction, including flow-mediated dilatation, a marker of endothelial dysfunction, ankle-brachial pulse wave velocity (baPWV, a marker of arterial stiffness, intima-media thickness (IMT, a marker of atherosclerosis, and the aortic calcification index (ACI, a marker of vascular calcification. RESULTS: The serum Klotho level significantly correlated with the 1,25-dihydroxyvitamin D level and inversely correlated with the parathyroid hormone level and the fractional excretion of phosphate. There were significant decreases in serum Klotho in patients with arterial stiffness defined as baPWV≥1400 cm/sec, atherosclerosis defined as maximum IMT≥1.1 mm and vascular calcification scores of ACI>0%. The serum Klotho level was a significant determinant of arterial stiffness, but not endothelial dysfunction, atherosclerosis or vascular calcification, in the multivariate analysis in either metabolic model, the CKD model or the CKD-MBD model. The adjusted odds ratio of serum Klotho for the baPWV was 0.60 (p = 0.0075. CONCLUSIONS: Decreases in the serum soluble Klotho levels are independently associated with signs of vascular dysfunction such as arterial stiffness in patients with CKD. Further research exploring whether therapeutic approaches

  9. The Effect of Sprint Start Speed on Lower-limb Stiffness in Sprint Runners

    Directory of Open Access Journals (Sweden)

    Mansour Eslami

    2015-09-01

    Full Text Available Objective: Lower extremity stiffness is associated with variables such as the frequency and length of running steps, the amount of muscle force and power production. Previous studies showed contradictory findings regarding the relationship between lower extremities joints stiffness and start velocity. Sprint start can be highly affected by two key components of lower limb stiffness, namely, force and time. However, no research has yet investigated the effect of start velocity changes on lower–limb stiffness during sprint start. To test the effect of velocity changes on lower-limb stiffness during sprint start. Method: 15 male members of track and field were selected for this study. Leg stiffness was calculated dividing peak ground reaction force by the leg length. Joint stiffness was also estimated dividing the muscle moment of force by joint angular displacement. Subjects performed a start with three different speeds. Results: From low to high start velocity, means of leg stiffness, knee stiffness and ankle stiffness increased by 67.53%, 41.9% and 39.03% respectively. Conclusion: The findings show that lower-limb stiffness could be a key factor in changing runners' acceleration during sprint start.

  10. Can Chronic Ankle Instability be Prevented? Rethinking Management of Lateral Ankle Sprains.

    Science.gov (United States)

    Denegar, Craig R.; Miller, Sayers J., III

    2002-01-01

    Investigates whether chronic ankle instability can be prevented, discussing: the relationship between mechanical and functional instability; normal ankle mechanics, sequelae to lateral ankle sprains, and abnormal ankle mechanics; and tissue healing, joint dysfunction, and acute lateral ankle sprain management. The paper describes a treatment model…

  11. Sex Differences in Limb and Joint Stiffness in Recreational Runners

    Directory of Open Access Journals (Sweden)

    Sinclair Jonathan

    2015-09-01

    Full Text Available Purpose. Female runners are known to be at greater risk from chronic running injuries than age-matched males, although the exact mechanisms are often poorly understood. The aim of the current investigation was to determine if female recreational runners exhibit distinct limb and joint stiffness characteristics in relation to their male counterparts. Methods. Fourteen male and fourteen female runners ran over a force platform at 4.0 m · s-1. Lower limb kinematics were collected using an eight-camera optoelectric motion capture system operating at 250 Hz. Measures of limb and joint stiffness were calculated as a function of limb length and joint moments divided by the extent of limb and joint excursion. All stiffness and joint moment parameters were normalized to body mass. Sex differences in normalized limb and knee and ankle joint stiffness were examined statistically using independent samples t tests. Results. The results indicate that normalized limb (male = 0.18 ± 0.07, female = 0.37 ± 0.10 kN · kg · m-1 and knee stiffness (male = 5.59 ± 2.02, female = 7.34 ± 1.78 Nm · kg · rad-1 were significantly greater in female runners. Conclusions. On the basis that normalized knee and limb stiffness were shown to be significantly greater in female runners, the findings from the current investigation may provide further insight into the aetiology of the distinct injury patterns observed between sexes.

  12. Treatment of Unstable Ankle Fractures

    Directory of Open Access Journals (Sweden)

    Yaniel Truffín Rodríguez

    2015-11-01

    Full Text Available Patients with unstable ankle fractures frequently attend the emergency rooms. It is estimated that there are 122 ankle fractures per 100 000 people a year. Surgical treatment of those that are unstable is inevitable since they can not be corrected in a conservative way. Several surgical procedures for repair of such lesions have been described and all of them constitute important tools for the orthopedic surgeon. Therefore, we conducted a literature review to discuss the current management of unstable ankle fractures based on the analysis of the published literature and the experiences in the Dr. Gustavo Aldereguía Lima University General Hospital of Cienfuegos.

  13. Effects of increasing physical activity on foot structure and ankle muscle strength in adults with obesity

    Science.gov (United States)

    Zhao, Xiaoguang; Tsujimoto, Takehiko; Kim, Bokun; Katayama, Yasutomi; Wakaba, Kyousuke; Wang, Zhennan; Tanaka, Kiyoji

    2016-01-01

    [Purpose] The purpose of this study was to examine the effects of increasing physical activity on foot structure and ankle muscle strength in adults with obesity and to verify whether the rate of change in foot structure is related to that in ankle muscle strength. [Subjects and Methods] Twenty-seven adults with obesity completed a 12-week program in which the intensity of physical activity performed was gradually increased. Physical activity was monitored using a three-axis accelerometer. Foot structure was assessed using a three-dimensional foot scanner, while ankle muscle strength was measured using a dynamometry. [Results] With the increasing physical activity, the participants’ feet became thinner (the rearfoot width, instep height, and girth decreased) and the arch became higher (the arch height index increased) and stiffer (the arch stiffness index increased); the ankle muscle strength also increased after the intervention. Additionally, the changes in the arch height index and arch stiffness index were not associated with changes in ankle muscle strength. [Conclusion] Increasing physical activity may be one possible approach to improve foot structure and function in individuals with obesity. PMID:27630426

  14. Changes in the stiffness of the human tibial cartilage-bone complex in early-stage osteoarthrosis

    DEFF Research Database (Denmark)

    Ding, Ming; Dalstra, M; Linde, F

    1998-01-01

    Cylindrical human tibial cartilage-bone unit specimens were removed from 9 early-stage medial osteoarthrotic (OA) tibiae (mean age 74 years) and 10 normal age-matched tibiae (mean age 73 years). These specimens were divided into 4 groups: OA, lateral comparison, medial age-matched, and lateral ag...... and bone remained significant in the three control groups. Our findings suggest that both cartilage and bone in early-stage OA are mechanically inferior to normal, and that OA cartilage and bone have lost their unit function to mechanical loading....

  15. Posttraumatic stiff elbow

    Directory of Open Access Journals (Sweden)

    Ravi Mittal

    2017-01-01

    Full Text Available Posttraumatic stiff elbow is a frequent and disabling complication and poses serious challenges for its management. In this review forty studies were included to know about the magnitude of the problem, causes, pathology, prevention, and treatment of posttraumatic stiff elbow. These studies show that simple measures such as internal fixation, immobilization in extension, and early motion of elbow joint are the most important steps that can prevent elbow stiffness. It also supports conservative treatment in selected cases. There are no clear guidelines about the choice between the numerous procedures described in literature. However, this review article disproves two major beliefs-heterotopic ossification is a bad prognostic feature, and passive mobilization of elbow causes elbow stiffness.

  16. Posttraumatic stiff elbow

    Science.gov (United States)

    Mittal, Ravi

    2017-01-01

    Posttraumatic stiff elbow is a frequent and disabling complication and poses serious challenges for its management. In this review forty studies were included to know about the magnitude of the problem, causes, pathology, prevention, and treatment of posttraumatic stiff elbow. These studies show that simple measures such as internal fixation, immobilization in extension, and early motion of elbow joint are the most important steps that can prevent elbow stiffness. It also supports conservative treatment in selected cases. There are no clear guidelines about the choice between the numerous procedures described in literature. However, this review article disproves two major beliefs-heterotopic ossification is a bad prognostic feature, and passive mobilization of elbow causes elbow stiffness.

  17. The effects of prosthetic ankle dorsiflexion and energy return on below-knee amputee leg loading.

    Science.gov (United States)

    Ventura, Jessica D; Klute, Glenn K; Neptune, Richard R

    2011-03-01

    Prosthetic devices are intended to return lower limb amputees to their pre-amputation functional status. However, prosthetic devices designed for unilateral below-knee amputees have yet to completely restore the biomechanical functions normally provided by the ankle muscles, leading to gait asymmetries and increased reliance on their intact leg. In an effort to improve amputee gait, energy storage and return feet have been developed that store mechanical energy in elastic structures in early to mid-stance and return it in late stance. However, little is known regarding how ankle compliance and the level of energy return influences walking mechanics. The purpose of this study was to identify the influence of prosthetic ankle dorsiflexion and energy storage and return on leg loading during steady-state walking. Compliant ankles with different stiffness levels were attached to a Seattle Lightfoot2 in different orientations (forward- and reverse-facing). The ankles decreased residual leg vertical ground reaction forces in late stance, increased residual leg propulsive ground reaction force impulses and increased residual leg knee joint extensor moments. The reverse-facing ankles increased residual leg vertical ground reaction forces in early stance, and the compliant forward-facing ankle increased residual leg braking impulses. In contrast to previous studies, increased energy storage and return from compliant ankles did not decrease hip joint powers or the intact leg vertical ground reaction forces. These results provide insight into the relationships between ankle dorsiflexion, energy storage and return, and leg loading, which may lead to more effective prosthetic devices to improve amputee gait. Copyright © 2010 Elsevier Ltd. All rights reserved.

  18. Broken Ankle/Broken Foot

    Science.gov (United States)

    ... so that your doctor can examine your gait. Imaging tests Not all foot and ankle injuries require ... an orthopedic surgeon may need to use pins, plates or screws to maintain proper position of your ...

  19. Effects of ankle balance taping with kinesiology tape for a patient with chronic ankle instability

    Science.gov (United States)

    Kim, Byeong-Jo; Lee, Jung-Hoon; Kim, Chang-Tae; Lee, Sun-Min

    2015-01-01

    [Purpose] To report the effects of ankle balance taping for a patient with chronic ankle instability (CAI). [Subject] A 33-year-old man with a 10 year history of chronic ankle stability. [Methods] ABT with kinesiology tape was performed for 2 months (average, 16 h/day) around the right ankle. [Results] At the end of two months, no ankle instability was noted when ascending and descending the stairs, jumping, turning, operating the pedals while driving, and lifting heavy objects. [Conclusion] The repeated use of kinesiology tape in ankle balance taping may be an effective treatment for recovering the ankle stability of patients with chronic ankle instability. PMID:26311206

  20. Effects of ankle balance taping with kinesiology tape for a patient with chronic ankle instability.

    Science.gov (United States)

    Kim, Byeong-Jo; Lee, Jung-Hoon; Kim, Chang-Tae; Lee, Sun-Min

    2015-07-01

    [Purpose] To report the effects of ankle balance taping for a patient with chronic ankle instability (CAI). [Subject] A 33-year-old man with a 10 year history of chronic ankle stability. [Methods] ABT with kinesiology tape was performed for 2 months (average, 16 h/day) around the right ankle. [Results] At the end of two months, no ankle instability was noted when ascending and descending the stairs, jumping, turning, operating the pedals while driving, and lifting heavy objects. [Conclusion] The repeated use of kinesiology tape in ankle balance taping may be an effective treatment for recovering the ankle stability of patients with chronic ankle instability.

  1. Changes in joint range of motion and muscle-tendon unit stiffness after varying amounts of dynamic stretching.

    Science.gov (United States)

    Mizuno, Takamasa

    2016-11-28

    The purpose of this study was to examine the effects of varying amounts of dynamic stretching (DS) on joint range of motion (ROM) and stiffness of the muscle-tendon unit (MTU). Fifteen healthy participants participated in four randomly ordered experimental trials, which involved one (DS1), four (DS4) and seven (DS7) sets of DS, or control conditions/seated at rest (CON). Each DS set consisted of 15 repetitions of an ankle dorsiflexion-plantarflexion movement. The displacement of the muscle-tendon junction (MTJ) was measured using ultrasonography while the ankle was passively dorsiflexed at 0.0174 rad · s(‒1) to its maximal dorsiflexion angle. Passive torque was also measured using an isokinetic dynamometer. Ankle ROM was significantly increased after DS4 and DS7 compared with the pre-intervention values (P < 0.05), but there were no significant differences in ankle ROM between DS4 and DS7. No differences were observed in ankle ROM after DS1 and CON. In addition, the stiffness of the MTU, passive torque and displacement of the MTJ at submaximal dorsiflexion angles did not change in any of the experimental conditions. These results indicate that DS4 increased ankle ROM without changing the mechanical properties of the MTU, and that this increase in ankle ROM plateaued after DS4.

  2. Total ankle replacement. Design evolution and results.

    Science.gov (United States)

    van den Heuvel, Alexander; Van Bouwel, Saskia; Dereymaeker, Greta

    2010-04-01

    The ankle joint has unique anatomical, biomechanical and cartilaginous structural characteristics that allow the joint to withstand the very high mechanical stresses and strains over years. Any minor changes to any of these features predispose the joint to osteoarthritis. Total ankle replacement (TAR) is evolving as an alternative to ankle arthrodesis for the treatment of end-stage ankle osteoarthritis. Initial implant designs from the early 1970s had unacceptably high failure and complication rates. As a result many orthopaedic surgeons have restricted the use of TAR in favour of ankle arthrodesis. Long term follow-up studies following ankle arthrodesis show risks of developing adjacent joint osteoarthritis. Therefore research towards a successful ankle replacement continues. Newer designs and longer-term outcome studies have renewed the interest in ankle joint replacement. We present an overview of the evolution, results and current concepts of total ankle replacement.

  3. The gearing function of running shoe longitudinal bending stiffness.

    Science.gov (United States)

    Willwacher, Steffen; König, Manuel; Braunstein, Björn; Goldmann, Jan-Peter; Brüggemann, Gert-Peter

    2014-07-01

    The purpose of the present study was to investigate whether altered longitudinal bending stiffness (LBS) levels of the midsole of a running shoe lead to a systematic change in lower extremity joint lever arms of the ground reaction force (GRF). Joint moments and GRF lever arms in the sagittal plane were determined from 19 male subjects running at 3.5 m/s using inverse dynamics procedures. LBS was manipulated using carbon fiber insoles of 1.9 mm and 3.2 mm thickness. Increasing LBS led to a significant shift of joint lever arms to a more anterior position. Effects were more pronounced at distal joints. Ankle joint moments were not significantly increased in the presence of higher GRF lever arms when averaged over all subjects. Still, two individual strategies (1: increase ankle joint moments while keeping push-off times almost constant, 2: decrease ankle joint moments and increase push-off times) could be identified in response to increased ankle joint lever arms that might reflect individual differences between subjects with respect to strength capacities or anthropometric characteristics. The results of the present study indicate that LBS systematically influences GRF lever arms of lower extremity joints during the push-off phase in running. Further, individual responses to altered LBS levels could be identified that could aid in finding optimum LBS values for a given individual. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Ankle blood pressure as a predictor of total and cardiovascular mortality

    Directory of Open Access Journals (Sweden)

    Salomaa Veikko

    2008-02-01

    Full Text Available Abstract Background The ankle blood pressure is commonly used as a ratio to the brachial blood pressure, called ankle-brachial index (ABI. Very few studies have considered the independent value of the ankle blood pressure without indexing it to the brachial blood pressure. We examined the value of ankle blood pressure, together with the exercise blood pressure, as a predictor of cardiovascular (CVD and total mortality. Methods A prospective follow-up study of 3,858 consecutive ambulatory patients (mean age 51 years, 65,9% male referred to a symptom-limited exercise test between August 1989 and December 1995. The cohort was followed up for all-cause and CVD mortality until December 31, 2004, by record linkage with the National Causes-of-Death Register. The independent value of ankle blood pressure as a predictor of cardiovascular and total mortality was assessed using Cox proportional hazards modelling. Results The average follow-up time was 14 years, during which 346 persons died, 108 of them due to CVD. Persons with normal ( Conclusion These results suggest that the ankle blood pressure has an independent value as a marker of arterial stiffness or subclinical atherosclerosis and a risk of future mortality in middle-aged, asymptomatic persons.

  5. Regional brain stiffness changes across the Alzheimer's disease spectrum.

    Science.gov (United States)

    Murphy, Matthew C; Jones, David T; Jack, Clifford R; Glaser, Kevin J; Senjem, Matthew L; Manduca, Armando; Felmlee, Joel P; Carter, Rickey E; Ehman, Richard L; Huston, John

    2016-01-01

    Magnetic resonance elastography (MRE) is an MRI-based technique to noninvasively measure tissue stiffness. Currently well established for clinical use in the liver, MRE is increasingly being investigated to measure brain stiffness as a novel biomarker of a variety of neurological diseases. The purpose of this work was to apply a recently developed MRE pipeline to measure regional brain stiffness changes in human subjects across the Alzheimer's disease (AD) spectrum, and to gain insights into the biological processes underlying those stiffness changes by correlating stiffness with existing biomarkers of AD. The results indicate that stiffness changes occur mostly in the frontal, parietal and temporal lobes, in accordance with the known topography of AD pathology. Furthermore, stiffness in those areas correlates with existing imaging biomarkers of AD including hippocampal volumes and amyloid PET. Additional analysis revealed preliminary but significant evidence that the relationship between brain stiffness and AD severity is nonlinear and non-monotonic. Given that similar relationships have been observed in functional MRI experiments, we used task-free fMRI data to test the hypothesis that brain stiffness was sensitive to structural changes associated with altered functional connectivity. The analysis revealed that brain stiffness is significantly and positively correlated with default mode network connectivity. Therefore, brain stiffness as measured by MRE has potential to provide new and essential insights into the temporal dynamics of AD, as well as the relationship between functional and structural plasticity as it relates to AD pathophysiology.

  6. Ankle Brachial Index

    Energy Technology Data Exchange (ETDEWEB)

    Wikstroem, J.; Hansen, T.; Johansson, L.; Lind, L.; Ahlstroem, H. (Dept. of Radiology and Dept. of Medical Sciences, Uppsala Univ. Hospital, Uppsala (SE))

    2008-03-15

    Background: Whole-body magnetic resonance angiography (WBMRA) permits noninvasive vascular assessment, which can be utilized in epidemiological studies. Purpose: To assess the relation between a low ankle brachial index (ABI) and high-grade stenoses in the pelvic and leg arteries in the elderly. Material and Methods: WBMRA was performed in a population sample of 306 subjects aged 70 years. The arteries below the aortic bifurcation were graded after the most severe stenosis according to one of three grades: 0-49% stenosis, 50-99% stenosis, or occlusion. ABI was calculated for each side. Results: There were assessable WBMRA and ABI examinations in 268 (right side), 265 (left side), and 258 cases (both sides). At least one >=50% stenosis was found in 19% (right side), 23% (left side), and 28% (on at least one side) of the cases. The corresponding prevalences for ABI <0.9 were 4.5%, 4.2%, and 6.6%. An ABI cut-off value of 0.9 resulted in a sensitivity, specificity, and positive and negative predictive value of 20%, 99%, 83%, and 84% on the right side, and 15%, 99%, 82%, and 80% on the left side, respectively, for the presence of a >= 50% stenosis in the pelvic or leg arteries. Conclusion: An ABI <0.9 underestimates the prevalence of peripheral arterial occlusive disease in the general elderly population

  7. Posterior Ankle Structure Injury During Total Ankle Replacement.

    Science.gov (United States)

    Reb, Christopher W; McAlister, Jeffrey E; Hyer, Christopher F; Berlet, Gregory C

    2016-01-01

    Total ankle replacement studies have focused on reporting complications that are directly observed clinically or radiographically, including wound problems, technical errors, implant loosening, subsidence, infection, bone fractures, and heterotopic ossification. However, patients can still experience unresolved pain even when these problems have been ruled out. We initiated a study to more clearly define the relative risk of injury to the anatomic structures in the posterior ankle during total ankle replacement using a third-generation implant system. Ten fresh-frozen adult cadaveric below-the-knee specimens were positioned in the intraoperative positioning frame of an approved total ankle replacement system and adjusted to achieve proper foot alignment using fluoroscopic imaging. The relationship between the tibial cutting guide pins and the posterior neurovascular and tendon structures was measured using digital calipers. High rates of posterior structural injury were found. Nearly all proximal-medial pins encountered a posteromedial neurovascular structure, most commonly the tibial nerve. The distal-medial pins mainly encountered posteromedial tendinous structures, in particular, the flexor digitorum longus tendon. The proximal lateral pins were highly likely to encounter the Achilles tendon and the sural nerve. Our results support our hypothesis that the tibial neurovascular structures are at the greatest risk when preparing for and completing the bony resection, particularly with the medial and proximal cuts. Posterior ankle soft tissue structure injuries can occur during implantation but currently with unknown frequency and undetermined significance. Further study of posterior structural injuries could result in a more informed approach to post-total ankle replacement complications and management.

  8. Dynamic stiffness of suction caissons

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Liingaard, Morten; Andersen, Lars

    The purpose of this report is to evaluate the dynamic soil-structure interaction of suction caissons for offshore wind turbines. The investigation is limited to a determination of the vertical dynamic stiffness of suction caissons. The soil surrounding the foundation is homogenous with linear...... of the skirt length, Poisson's ratio and the ratio between soil stiffness and skirt stiffness. Finally the dynamic behaviour at high frequencies is investigated....... viscoelastic properties. The dynamic stiffness of the suction caisson is expressed by dimensionless frequency-dependent dynamic stiffness coefficients corresponding to the vertical degree of freedom. The dynamic stiffness coefficients for the foundations are evaluated by means of a dynamic three...

  9. Cryotherapy induces an increase in muscle stiffness.

    Science.gov (United States)

    Point, Maxime; Guilhem, Gaël; Hug, François; Nordez, Antoine; Frey, Alain; Lacourpaille, Lilian

    2017-03-06

    Although cold application (i.e., cryotherapy) may be useful to treat sports injuries and to prevent muscle damage, it is unclear whether it has adverse effects on muscle mechanical properties. This study aimed to determine the effect of air-pulsed cryotherapy on muscle stiffness estimated using ultrasound shear wave elastography. Myoelectrical activity, ankle passive torque, shear modulus (an index of stiffness) and muscle temperature of the gastrocnemius medialis were measured before, during an air-pulsed cryotherapy (-30°) treatment of 4 sets of 4 minutes with 1 min recovery in between, and during a 40-min post-cryotherapy period. Muscle temperature significantly decreased after the second set of treatment (10 min: 32.3 ± 2.5°C; P < 0.001), peaked at 29 min (27.9 ± 2.2°C; P < 0.001) and remained below baseline values at 60 minutes (29.5 ± 2.0°C; P < 0.001). Shear modulus increased by +11.5 ± 11.8% after the second set (10 min; P = 0.011), peaked at 30 min (+34.7 ± 42.6%; P < 0.001) and remained elevated until the end of the post-treatment period (+25.4 ± 17.1%; P < 0.001). These findings provide evidence that cryotherapy induces an increase in muscle stiffness. This acute change in muscle mechanical properties may lower the amount of stretch that the muscle tissue is able to sustain without subsequent injury. This should be considered when using cryotherapy in athletic practice. This article is protected by copyright. All rights reserved.

  10. Motion Simulation of a New Ankle Rehabilitation Device

    Directory of Open Access Journals (Sweden)

    Cristina Racu (Cazacu

    2016-06-01

    Full Text Available The ankle structure holds one of the most important role in the human biomechanics. Due to complexity of everyday activities this joint is the most prone to be injured part of the lower limb. For a complete recovery of the locomotion function, recovery exercises are mandatory. The introduction of robotic physical recovery systems represents a modern alternative to traditional recovery. Based on the 3D virtual model and a previous dimensional synthesis of a new ankle rehabilitation device, its motion simulation is presented in this paper, to prove that it may fully recover the range of motion required for this joint.

  11. Modeling and stress analyses of a normal foot-ankle and a prosthetic foot-ankle complex.

    Science.gov (United States)

    Ozen, Mustafa; Sayman, Onur; Havitcioglu, Hasan

    2013-01-01

    Total ankle replacement (TAR) is a relatively new concept and is becoming more popular for treatment of ankle arthritis and fractures. Because of the high costs and difficulties of experimental studies, the developments of TAR prostheses are progressing very slowly. For this reason, the medical imaging techniques such as CT, and MR have become more and more useful. The finite element method (FEM) is a widely used technique to estimate the mechanical behaviors of materials and structures in engineering applications. FEM has also been increasingly applied to biomechanical analyses of human bones, tissues and organs, thanks to the development of both the computing capabilities and the medical imaging techniques. 3-D finite element models of the human foot and ankle from reconstruction of MR and CT images have been investigated by some authors. In this study, data of geometries (used in modeling) of a normal and a prosthetic foot and ankle were obtained from a 3D reconstruction of CT images. The segmentation software, MIMICS was used to generate the 3D images of the bony structures, soft tissues and components of prosthesis of normal and prosthetic ankle-foot complex. Except the spaces between the adjacent surface of the phalanges fused, metatarsals, cuneiforms, cuboid, navicular, talus and calcaneus bones, soft tissues and components of prosthesis were independently developed to form foot and ankle complex. SOLIDWORKS program was used to form the boundary surfaces of all model components and then the solid models were obtained from these boundary surfaces. Finite element analyses software, ABAQUS was used to perform the numerical stress analyses of these models for balanced standing position. Plantar pressure and von Mises stress distributions of the normal and prosthetic ankles were compared with each other. There was a peak pressure increase at the 4th metatarsal, first metatarsal and talus bones and a decrease at the intermediate cuneiform and calcaneus bones, in

  12. Stiff Quantum Polymers

    OpenAIRE

    Kleinert, H

    2007-01-01

    At ultralow temperatures, polymers exhibit quantum behavior, which is calculated here for the second and fourth moments of the end-to-end distribution in the large-stiffness regime. The result should be measurable for polymers in wide optical traps.

  13. Effects of ankle eversion taping using kinesiology tape in a patient with ankle inversion sprain.

    Science.gov (United States)

    Lee, Sun-Min; Lee, Jung-Hoon

    2016-01-01

    [Purpose] The aim of this study was to report the effects of ankle eversion taping using kinesiology tape on ankle inversion sprain. [Subject] The subject was a 21-year-old woman with Grade 2 ankle inversion sprain. [Methods] Ankle eversion taping was applied to the sprained left ankle using kinesiology tape for 4 weeks (average, 15 h/day). [Results] Ankle instability and pain were reduced, and functional dynamic balance was improved after ankle eversion taping for 4 weeks. The Cumberland Ankle Instability Tool score and reach distances in the Y-Balance and lunge tests were increased. [Conclusion] Repeated ankle eversion taping may be an effective treatment intervention for ankle inversion sprain.

  14. Acute effects of aerobic exercise intensity on arterial stiffness after glucose ingestion in young men.

    Science.gov (United States)

    Kobayashi, Ryota; Hashimoto, Yuto; Hatakeyama, Hiroyuki; Okamoto, Takanobu

    2016-10-18

    Arterial stiffness increases after glucose ingestion. Acute low- and moderate-intensity aerobic exercise decreases arterial stiffness. However, the acute effects of 30 min of cycling at low- and moderate-intensity [25% (LE trial) and 65% (ME trial) peak oxygen uptake, respectively] on arterial stiffness at 30, 60 and 120 min of a postexercise glucose ingestion. Ten healthy young men (age, 22·4 ± 0·5 years) performed LE and ME trials on separate days in a randomized controlled crossover fashion. Carotid-femoral (aortic) pulse wave velocity (PWV), femoral-ankle (leg) PWV, carotid augmentation index (AIx) and carotid blood pressure (BP) (applanation tonometry), brachial and ankle BP (oscillometric device), heart rate (HR) (electrocardiography), blood glucose (UV-hexokinase method) and blood insulin (CLEIA method) levels were measured at before (baseline) and at 30, 60 and 120 min after the 75-g OGTT. Leg PWV, ankle pulse pressure and BG levels significantly increased from baseline after the 75-g OGTT in the LE trial (P<0·05), but not in the ME trial. Insulin levels and HR significantly increased from baseline after the 75-g OGTT in both trials (P<0·05). Aortic PWV, carotid AIx, brachial BP and carotid BP did not change from baseline after the 75-g OGTT in both trials. The present findings indicate that aerobic exercise at moderate intensity before glucose ingestion suppresses increases leg arterial stiffness after glucose ingestion.

  15. The Incidence of Ankle Sprains in Orienteering.

    Science.gov (United States)

    Ekstrand, Jan; And Others

    1990-01-01

    Investigates relationship between ankle sprains and participation time in competitive orienteering. Examined 15,474 competitors in races in the Swedish O-ringen 5-day event in 1987. Injuries requiring medical attention were analyzed, showing 137 (23.9 percent) ankle sprains. Injury incidence was 8.4/10,000 hours. Incidence of ankle sprains was…

  16. Acute Ankle Sprains in Primary Care

    NARCIS (Netherlands)

    R.M. van Rijn (Rogier)

    2010-01-01

    textabstractOf all injuries of the musculoskeletal system, 25% are acute lateral ankle sprains.1 In the USA and the UK there are about 23,000 and 5000 ankle sprains, respectively, each day. In the Netherlands approximately 600,000 people sustain an ankle injury each year, of those 120,000 occur duri

  17. Effect of coronary occlusion during percutaneous transluminal angioplasty in humans on left ventricular chamber stiffness and regional diastolic pressure-radius relations

    NARCIS (Netherlands)

    W. Wijns (William); P.W.J.C. Serruys (Patrick); C.J. Slager (Cornelis); J. Grimm; H.P. Krayenbuehl; P.G. Hugenholtz (Paul); O.M. Hess (Otto)

    1986-01-01

    textabstractThe effect of repeated (3 to 10 second) and transient (15 to 75 second) abrupt coronary occlusion on the global and regional chamber stiffness was studied in nine patients undergoing angioplasty of a single proximal left anterior descending coronary artery stenosis. The left ventricular

  18. Depression, Anxiety, and Arterial Stiffness

    NARCIS (Netherlands)

    Seldenrijk, Adrie; van Hout, Hein P. J.; van Marwijk, Harm W. J.; de Groot, Eric; Gort, Johan; Rustemeijer, Cees; Diamant, Michaela; Penninx, Brenda W. J. H.

    2011-01-01

    Background: Arterial stiffness gains attention as a potential mechanism underlying the frequently found association between depression or anxiety and cardiovascular disease. However, observations regarding stiffness and psychopathology were often based on small samples. The current study aimed to

  19. Genetics of Stiff Child Syndrome

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2005-11-01

    Full Text Available A Chinese boy with a DYT1 gene mutation presented with muscle stiffness, painful muscle spasms, myoclonus, and dystonia, compatible with stiff child syndrome, and is reported from Queen Mary Hospital, the University of Hong Kong.

  20. Effect of Reduced Stiffness Dance Flooring on Lower Extremity Joint Angular Trajectories During a Ballet Jump.

    Science.gov (United States)

    Hackney, James; Brummel, Sara; Newman, Mary; Scott, Shannon; Reinagel, Matthew; Smith, Jennifer

    2015-09-01

    We carried out a study to investigate how low stiffness flooring may help prevent overuse injuries of the lower extremity in dancers. It was hypothesized that performing a ballet jump (sauté) on a reduced stiffness dance floor would decrease maximum joint flexion angles and negative angular velocities at the hips, knees, or ankles compared to performing the same jump on a harder floor. The participants were 15 young adult female dancers (age range 18 to 28, mean = 20.89 ± 2.93 years) with at least 5 years of continuous ballet experience and without history of serious lower body injury, surgery, or recent pain. They performed sautés on a (low stiffness) Harlequin ® WoodSpring Floor and on a vinyl-covered hardwood on concrete floor. Maximum joint flexion angles and negative velocities at bilateral hips, knees, and ankles were measured with the "Ariel Performance Analysis System" (APAS). Paired one-tailed t-tests yielded significant decreases in maximum knee angle (average decrease = 3.4° ± 4.2°, p = 0.026) and angular negative velocity of the ankles (average decrease = 18.7°/sec ± 27.9°/sec, p = 0.009) with low stiffness flooring. If the knee angle is less acute, then the length of the external knee flexion moment arm will also be shorter and result in a smaller external knee flexion moment, given an equal landing force. Also, high velocities of eccentric muscle contraction, which are necessary to control negative angular velocity of the ankle joint, are associated with higher risk of musculotendinous injury. Hence, our findings indicate that reduced floor stiffness may indeed help decrease the likelihood of lower extremity injuries.

  1. Ankle Joint Angle and Lower Leg Musculotendinous Unit Responses to Cryotherapy.

    Science.gov (United States)

    Akehi, Kazuma; Long, Blaine C; Warren, Aric J; Goad, Carla L

    2016-09-01

    Akehi, K, Long, BC, Warren, AJ, and Goad, CL. Ankle joint angle and lower leg musculotendinous unit responses to cryotherapy. J Strength Cond Res 30(9): 2482-2492, 2016-The use of cold application has been debated for its influence on joint range of motion (ROM) and stiffness. The purpose of this study was to determine whether a 30-minute ice bag application to the plantarflexor muscles or ankle influences passive ankle dorsiflexion ROM and lower leg musculotendinous stiffness (MTS). Thirty-five recreationally active college-aged individuals with no history of lower leg injury 6 months before data collection volunteered. On each testing day, we measured maximum passive ankle dorsiflexion ROM (°) and plantarflexor torque (N·m) on an isokinetic dynamometer to calculate the passive plantarflexor MTS (N·m per degree) at 4 joint angles before, during, and after a treatment. Surface electromyography amplitudes (μV), and skin surface and ambient air temperature (°C) were also measured. Subjects received an ice bag to the posterior lower leg, ankle joint, or nothing for 30 minutes in different days. Ice bag application to the lower leg and ankle did not influence passive ROM (F(12,396) = 0.67, p = 0.78). Passive torque increased after ice bag application to the lower leg (F(12,396) = 2.21, p = 0.011). Passive MTS at the initial joint angle increased after ice bag application to the lower leg (F(12,396) = 2.14, p = 0.014) but not at the other joint angles (p > 0.05). Surface electromyography amplitudes for gastrocnemius and soleus muscles increased after ice application to the lower leg (F(2,66) = 5.61, p = 0.006; F(12,396) = 3.60, p < 0.001). Ice bag application to the lower leg and ankle joint does not alter passive dorsiflexion ROM but increases passive ankle plantarflexor torque in addition to passive ankle plantarflexor MTS at the initial joint angle.

  2. The Effect of Rib Shape on Stiffness.

    Science.gov (United States)

    Holcombe, Sven A; Wang, Stewart C; Grotberg, James B

    2016-11-01

    This study investigates the isolated effect of rib shape on the mechanical characteristics of ribs subjected to multiple forms of loading. It aims to measure the variation in stiffness due to shape that is seen throughout the population and, in particular, provide a tool for researchers to better understand the influence of shape on resulting stiffness. A previously published six-parameter shape model of the central axis of human ribs was used. It has been shown to accurately model the overall rib path using intrinsic geometric properties such as size, aspect ratio, and skewness, through shapes based on logarithmic spirals with high curvature continuity. In this study the model was fitted to 19,500 ribs from 989 adult female and male CT scans having demographic distributions matching the US adult population. Mechanical loading was simulated through a simplified finite element model aimed at isolating rib shape from other factors influencing mechanical response. Four loading scenarios were used representing idealized free and constrained loading conditions in axial (body-anterior) and lateral directions. Characteristic rib stiffness and maximum stress location were tracked as simulation output measures. Regression models of rib stiffness found that all shape model parameters added information when predicting stiffness under each loading condition, with their linear combination able to account for 95% of the population stiffness variation due to shape in midlevel ribs for free axial loading, and 92%-98% in other conditions. Full regression models including interactive terms explained up to 99% of population variability. Results allow researchers to better evaluate the differences in stiffness results that are obtained from physical testing by providing a framework with which to explain variation due to rib shape.

  3. Physical inactivity and arterial stiffness in COPD

    Directory of Open Access Journals (Sweden)

    Sievi NA

    2015-09-01

    Full Text Available Noriane A Sievi,1 Daniel Franzen,1 Malcolm Kohler,1,2 Christian F Clarenbach1 1Division of Pulmonology, University Hospital of Zurich, 2Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland Background: Arterial stiffness is an important predictor of cardiovascular risk besides classic cardiovascular risk factors. Previous studies showed that arterial stiffness is increased in patients with COPD compared to healthy controls and exercise training may reduce arterial stiffness. Since physical inactivity is frequently observed in patients with COPD and exercise training may improve arterial stiffness, we hypothesized that low daily physical activity may be associated with increased arterial stiffness. Methods: In 123 patients with COPD (72% men; mean [standard deviation] age: 62 [7.5] years; median [quartile] forced expiratory volume in 1 second 35 [27/65] %predicted, arterial stiffness was assessed by augmentation index (AI. Daily physical activity level (PAL was measured by an activity monitor (SenseWear Pro™ >1 week. The association between AI and PAL was investigated by univariate and multivariate regression analysis, taking into account disease-specific characteristics and comorbidities. Results: Patients suffered from moderate (35%, severe (32%, and very severe (33% COPD, and 22% were active smokers. Median (quartile PAL was 1.4 (1.3/1.5 and mean (standard deviation AI 26% (9.2%. PAL showed a negative association with AI (B=-9.32, P=0.017 independent of age, sex, blood pressure, and airflow limitation. Conclusion: In COPD patients, a higher PAL seems to favorably influence arterial stiffness and therefore may reduce cardiovascular risk. Clinical Trial Registration: www.ClinicalTrials.gov, NCT01527773 Keywords: activity monitor, airflow limitation, COPD, physical activity level

  4. [Contraction properties and musculo-tendinous stiffness of the human triceps surae muscle and their change as a result of a long-term bed-rest].

    Science.gov (United States)

    Koriak, Iu A

    2012-01-01

    The effect of a 120-day 5 degree head-down tilt (HDT) bed rest on the mechanical properties and electromechanical delay (EMD) of the human triceps surae (TS) muscle was studied in four (mean age 31.5+/-1.7 yr) healthy young women subjects. The TS mechanical properties were evaluated based on the following indicators: maximal voluntary contraction (MVC), maximal strength (Po; frequency 150 Hz), peak twitch force (Poc), time-to-peak tension (TPT), half-relaxation time (1/2 RT) and tension development time to reach 25, 50, 75 and 90% of maximal tension. Force deficit (Pd) were estimated. In response to a light signal,the subject was supposed to make a voluntary foot flexion, with the instruction "to exert the fastest and greatest tension". EMD measurements were recorded from each subject during voluntary contraction. Surface electrodes sensed electromyographic (EMG) activity in the soleus muscle. A separate timer was used to determine total reaction time (TRT). Premotor time (PMT) was taken to be the time interval from the delivery of the signal to change in EMG. EMD was the time interval between the change in EMG and movement i.e. the time interval between EMG and the onset of muscle tension. After HDT Poe, MVC and Po decreased by 24.4, 36.1 and 11.5%, respectively, while Pd increased by 38.8%. TPT increased by 13.6%, while 1/2RT decreased by 19.2%. The rate of increase of voluntary contractions calculated according to a relative scale significantly increased, while the rate of development of electrically evoked contraction did not show any significant differences. The voluntary contraction EMD increased by 27.4%; PMT by 8.7%, and TRT by 13.6%. Thus, the mechanical changes suggest that weightlessness changes not only the peripheral processes associated with contractions but also the central and neural command. EMD is a simple and quick method for evaluation of muscle stiffness changes. Moreover, EMD can serve as an indicator of the functional condition of the

  5. Powered ankle-foot prosthesis for the improvement of amputee ambulation.

    Science.gov (United States)

    Au, Samuel K; Herr, Hugh; Weber, Jeff; Martinez-Villalpando, Ernesto C

    2007-01-01

    This paper presents the mechanical design, control scheme, and clinical evaluation of a novel, motorized ankle-foot prosthesis, called MIT Powered Ankle-Foot Prosthesis. Unlike a conventional passive-elastic ankle-foot prosthesis, this prosthesis can provide active mechanical power during the stance period of walking. The basic architecture of the prosthesis is a unidirectional spring, configured in parallel with a force-controllable actuator with series elasticity. With this architecture, the anklefoot prosthesis matches the size and weight of the human ankle, and is also capable of delivering high mechanical power and torque observed in normal human walking. We also propose a biomimetic control scheme that allows the prosthesis to mimic the normal human ankle behavior during walking. To evaluate the performance of the prosthesis, we measured the rate of oxygen consumption of three unilateral transtibial amputees walking at self-selected speeds to estimate the metabolic walking economy. We find that the powered prosthesis improves amputee metabolic economy from 7% to 20% compared to the conventional passive-elastic prostheses (Flex-Foot Ceterus and Freedom Innovations Sierra), even though the powered system is twofold heavier than the conventional devices. This result highlights the benefit of performing net positive work at the ankle joint to amputee ambulation and also suggests a new direction for further advancement of an ankle-foot prosthesis.

  6. Lucy's flat feet: the relationship between the ankle and rearfoot arching in early hominins.

    Directory of Open Access Journals (Sweden)

    Jeremy M DeSilva

    Full Text Available BACKGROUND: In the Plio-Pleistocene, the hominin foot evolved from a grasping appendage to a stiff, propulsive lever. Central to this transition was the development of the longitudinal arch, a structure that helps store elastic energy and stiffen the foot during bipedal locomotion. Direct evidence for arch evolution, however, has been somewhat elusive given the failure of soft-tissue to fossilize. Paleoanthropologists have relied on footprints and bony correlates of arch development, though little consensus has emerged as to when the arch evolved. METHODOLOGY/PRINCIPAL FINDINGS: Here, we present evidence from radiographs of modern humans (n = 261 that the set of the distal tibia in the sagittal plane, henceforth referred to as the tibial arch angle, is related to rearfoot arching. Non-human primates have a posteriorly directed tibial arch angle, while most humans have an anteriorly directed tibial arch angle. Those humans with a posteriorly directed tibial arch angle (8% have significantly lower talocalcaneal and talar declination angles, both measures of an asymptomatic flatfoot. Application of these results to the hominin fossil record reveals that a well developed rearfoot arch had evolved in Australopithecus afarensis. However, as in humans today, Australopithecus populations exhibited individual variation in foot morphology and arch development, and "Lucy" (A.L. 288-1, a 3.18 Myr-old female Australopithecus, likely possessed asymptomatic flat feet. Additional distal tibiae from the Plio-Pleistocene show variation in tibial arch angles, including two early Homo tibiae that also have slightly posteriorly directed tibial arch angles. CONCLUSIONS/SIGNIFICANCE: This study finds that the rearfoot arch was present in the genus Australopithecus. However, the female Australopithecus afarensis "Lucy" has an ankle morphology consistent with non-pathological flat-footedness. This study suggests that, as in humans today, there was variation in arch

  7. Possible factors for ankle fractures

    Directory of Open Access Journals (Sweden)

    Tabaković Dejan

    2010-01-01

    Full Text Available Background/Aim. Classification of ankle fractures is commonly used for selecting an appropriate treatment and prognosing an outcome of definite management. One of the most used classifications is the Danis-Weber classification. To the best of our knowledge, in the available literature, there are no parameters affecting specific types of ankle fractures according to the Danis-Weber classification. The aim of this study was to analyze the correlation of the following parameters: age, body weight, body mass index (BMI, height, osteoporosis, osteopenia and physical exercises with specific types of ankle fractures using the Danis-Weber classification. Methods. A total of 85 patients grouped by the Danis-Weber classification fracture types were analyzed and the significance of certain parameters for specific types of ankle fractures was established. Results. The proportion of females was significantly higher (p < 0.001 with a significantly higher age (59.9 years, SD ± 14.2 in relation to males (45.1 years, SD ± 12.8 (p < 0.0001. Type A fracture was most frequent in the younger patients (34.2 years, SD ± 8.6, and those with increased physical exercises (p = 0.020. In type B fracture, the risk factor was osteoporosis (p = 0.0180, while in type C fracture, body weight (p = 0.017 and osteoporosis (p = 0.004 were significant parameters. Conclusion. Statistical analysis using the Danis-Weber classification reveals that there are certain parameters suggesting significant risk factors for specific types of ankle fractures.

  8. On gear tooth stiffness evaluation

    DEFF Research Database (Denmark)

    Pedersen, Niels Leergaard; Jørgensen, Martin Felix

    2014-01-01

    The estimation of gear stiffness is important for determining the load distribution between the gear teeth when two sets of teeth are in contact. Two factors have a major influence on the stiffness; firstly the boundary condition through the gear rim size included in the stiffness calculation...... and secondly the size of the contact. In the FE calculation the true gear tooth root profile is applied. The meshing stiffnesses of gears are highly non-linear, it is however found that the stiffness of an individual tooth can be expressed in a linear form assuming that the contact width is constant. © 2014...

  9. Design and validation of a platform robot for determination of ankle impedance during ambulation.

    Science.gov (United States)

    Rouse, Elliott J; Hargrove, Levi J; Peshkin, Michael A; Kuiken, Todd A

    2011-01-01

    In order to provide natural, biomimetic control to recently developed powered ankle prostheses, we must characterize the impedance of the ankle during ambulation tasks. To this end, a platform robot was developed that can apply an angular perturbation to the ankle during ambulation and simultaneously acquire ground reaction force data. In this study, we detail the design of the platform robot and characterize the impedance of the ankle during quiet standing. Subjects were perturbed by a 3° dorsiflexive ramp perturbation with a length of 150 ms. The impedance was defined parametrically, using a second order model to map joint angle to the torque response. The torque was determined using the inverted pendulum assumption, and impedance was identified by the least squares best estimate, yielding an average damping coefficient of 0.03 ± 0.01 Nms/° and an average stiffness coefficient of 3.1 ± 1.2 Nm/°. The estimates obtained by the proposed platform robot compare favorably to those published in the literature. Future work will investigate the impedance of the ankle during ambulation for powered prosthesis controller development.

  10. Ankle inversion taping using kinesiology tape for treating medial ankle sprain in an amateur soccer player.

    Science.gov (United States)

    Lee, Sun-Min; Lee, Jung-Hoon

    2015-07-01

    [Purpose] The purpose of this study was to report the effects of ankle inversion taping using kinesiology tape in a patient with a medial ankle sprain. [Subject] A 28-year-old amateur soccer player suffered a Grade 2 medial ankle sprain during a match. [Methods] Ankle inversion taping was applied to the sprained ankle every day for 2 months. [Results] His symptoms were reduced after ankle inversion taping application for 2 months. The self-reported function score, the reach distances in the Star Excursion Balance Test, and the weight-bearing ankle dorsiflexion were increased. [Conclusion] This study showed that ankle inversion taping using kinesiology tape may be an effective therapy for a patient with a medial ankle sprain.

  11. Musculotendinous Stiffness of Triceps Surae, Maximal Rate of Force Development, and Vertical Jump Performance

    Directory of Open Access Journals (Sweden)

    Tarak Driss

    2015-01-01

    Full Text Available The relationships between ankle plantar flexor musculotendinous stiffness (MTS and performance in a countermovement vertical jump (CMJ and maximal rate of torque development (MRTD were studied in 27 active men. MTS was studied by means of quick releases at 20 (S0.2, 40 (S0.4, 60 (S0.6, and 80% (S0.8 of maximal voluntary torque (TMVC. CMJ was not correlated with strength indices but was positively correlated with MRTD/BM, S0.4/BM. The slope α2 and intercept β2 of the torque-stiffness relationships from 40 to 80% TMVC were correlated negatively (α2 and positively (β2 with CMJ. The different stiffness indices were not correlated with MRTD. The prediction of CMJ was improved by the introduction of MRTD in multiple regressions between CMJ and stiffness. CMJ was also negatively correlated with indices of curvature of the torque-stiffness relationship. The subjects were subdivided in 3 groups in function of CMJ (groups H, M, and L for high, medium, and low performers, resp.. There was a downward curvature of the torque-stiffness relationship at high torques in group H or M and the torque-stiffness regression was linear in group L only. These results suggested that torque-stiffness relationships with a plateau at high torques are more frequent in the best jumpers.

  12. Musculotendinous stiffness of triceps surae, maximal rate of force development, and vertical jump performance.

    Science.gov (United States)

    Driss, Tarak; Lambertz, Daniel; Rouis, Majdi; Jaafar, Hamdi; Vandewalle, Henry

    2015-01-01

    The relationships between ankle plantar flexor musculotendinous stiffness (MTS) and performance in a countermovement vertical jump (CMJ) and maximal rate of torque development (MRTD) were studied in 27 active men. MTS was studied by means of quick releases at 20 (S0.2), 40 (S0.4), 60 (S0.6), and 80% (S0.8) of maximal voluntary torque (T(MVC)). CMJ was not correlated with strength indices but was positively correlated with MRTD/BM, S 0.4/BM. The slope α 2 and intercept β 2 of the torque-stiffness relationships from 40 to 80% T(MVC) were correlated negatively (α 2) and positively (β 2) with CMJ. The different stiffness indices were not correlated with MRTD. The prediction of CMJ was improved by the introduction of MRTD in multiple regressions between CMJ and stiffness. CMJ was also negatively correlated with indices of curvature of the torque-stiffness relationship. The subjects were subdivided in 3 groups in function of CMJ (groups H, M, and L for high, medium, and low performers, resp.). There was a downward curvature of the torque-stiffness relationship at high torques in group H or M and the torque-stiffness regression was linear in group L only. These results suggested that torque-stiffness relationships with a plateau at high torques are more frequent in the best jumpers.

  13. The Effects of Barefoot and Shod Running on Limb and Joint Stiffness Characteristics in Recreational Runners.

    Science.gov (United States)

    Sinclair, Jonathan; Atkins, Stephen; Taylor, Paul J

    2016-01-01

    The authors aimed to determine the effects of barefoot (BF) and several commercially available barefoot-inspired (BFIS) footwear models on limb and joint stiffness characteristics compared with conventional footwear (CF). Fifteen male participants ran over a force platform at 4.0 m.s(-1), in BF, BFIS, and CF conditions. Measures of limb and joint stiffness were calculated for each footwear. The results indicate that limb and knee stiffness were greater in BF and minimalist BFIS than in CF. CF and more structured BFIS were associated with a greater ankle stiffness compared with BF and minimalist BFIS. These findings serve to provide further insight into the susceptibility of runners to different injury mechanisms as a function of footwear.

  14. High trans but not saturated fat beverage causes an acute reduction in postprandial vascular endothelial function but not arterial stiffness in humans.

    Science.gov (United States)

    Lane-Cordova, Abbi D; Witmer, Jordan R; Dubishar, Kaitlyn; DuBose, Lyndsey E; Chenard, Catherine A; Siefers, Kyle J; Myers, Janie E; Points, Lauren J; Pierce, Gary L

    2016-10-01

    A diet high in trans-fatty acids (TFAs) is associated with a higher risk of cardiovascular disease (CVD) than a diet high in saturated fatty acids (SFAs), but the mechanisms remain unclear. We hypothesized that a beverage high in TFAs would cause a larger reduction in postprandial endothelial function and an increase in arterial stiffness, in part from greater reductions in insulin sensitivity, compared with a beverage high in SFAs. Eleven healthy adults (aged 47±5 years) ingested a warm test beverage (520 kcal, 56 g total fat, 5 g carbohydrate, 1 g protein) high in either TFAs or SFAs in a randomized cross-over study. Ingestion of the beverage high in TFAs (p<0.01) but not high in SFAs (p=0.49) decreased endothelial function (brachial artery flow-mediated dilation, mmΔ) at 3-4 hours (p<0.01 for time; p=0.034 for interaction), but did not alter aortic stiffness or carotid β-stiffness. The homeostasis model of insulin resistance (interaction p=0.062) tended to decrease after SFAs but not TFAs. A beverage high in TFAs but not SFAs results in a postprandial reduction in endothelial function and a trend for decreased insulin sensitivity, potentially explaining the higher risk of CVD with a diet high in TFAs. © The Author(s) 2016.

  15. Design and simulation of a cable-pulley-based transmission for artificial ankle joints

    Science.gov (United States)

    Liu, Huaxin; Ceccarelli, Marco; Huang, Qiang

    2016-06-01

    In this paper, a mechanical transmission based on cable pulley is proposed for human-like actuation in the artificial ankle joints of human-scale. The anatomy articular characteristics of the human ankle is discussed for proper biomimetic inspiration in designing an accurate, efficient, and robust motion control of artificial ankle joint devices. The design procedure is presented through the inclusion of conceptual considerations and design details for an interactive solution of the transmission system. A mechanical design is elaborated for the ankle joint angular with pitch motion. A multi-body dynamic simulation model is elaborated accordingly and evaluated numerically in the ADAMS environment. Results of the numerical simulations are discussed to evaluate the dynamic performance of the proposed design solution and to investigate the feasibility of the proposed design in future applications for humanoid robots.

  16. The Scandinavian Total Ankle Replacement and the ideal biomechanical requirements of ankle replacements.

    Science.gov (United States)

    Robati, Shibby; Salih, Alan; Ghosh, Koushik; Vinayakam, Parthiban

    2016-03-01

    The complex anatomy of the articular bone surfaces, ligaments, tendon attachments and muscles makes the ankle joint difficult to replicate in prosthetic replacements. Ever since the early 1970s, which saw the dawn of the first total ankle replacements, there have been numerous other attempts at replicating the joint, often with poor clinical outcomes. The anatomy of the ankle is discussed, followed by evidence of the normal ankle biomechanics and the ideal requirements of an ankle replacement. We focus on the Scandinavian Total Ankle Replacement and evaluate whether these requirements have been met.

  17. Reduced effects of tendon vibration with increased task demand during active, cyclical ankle movements

    Science.gov (United States)

    Floyd, Lisa M.; Holmes, Taylor C.; Dean, Jesse C.

    2013-01-01

    Tendon vibration can alter proprioceptive feedback, one source of sensory information which humans can use to produce accurate movements. However, the effects of tendon vibration during functional movement vary depending on the task. For example, ankle tendon vibration has considerably smaller effects during walking than standing posture. The purpose of this study was to test whether the effects of ankle tendon vibration are predictably influenced by the mechanical demands of a task, as quantified by peak velocity. Twelve participants performed symmetric, cyclical ankle plantarflexion/dorsiflexion movements while lying prone with their ankle motion unconstrained. The prescribed movement period (1s, 3s) and peak-to-peak amplitude (10°, 15°, 20°) were varied across trials; shorter movement periods or larger amplitudes increased the peak velocity. In some trials, vibration was continuously and simultaneously applied to the right ankle plantarflexor and dorsiflexor tendons, while the left ankle tendons were never vibrated. The vibration frequency (40, 80, 120, 160 Hz) was varied across trials. During trials without vibration, participants accurately matched the movement of their ankles. The application of 80 Hz vibration to the right ankle tendons significantly reduced the amplitude of right ankle movement. However, the effect of vibration was smaller during more mechanically demanding (i.e. higher peak velocity) movements. Higher vibration frequencies had larger effects on movement accuracy, possibly due to parallel increases in vibration amplitude. These results demonstrate that the effects of ankle tendon vibration are dependent on the mechanical demand of the task being performed, but cannot definitively identify the underlying physiological mechanism. PMID:24136344

  18. Mechanics of dog walking compared with a passive, stiff-limbed, 4-bar linkage model, and their collisional implications.

    Science.gov (United States)

    Usherwood, James R; Williams, Sarah B; Wilson, Alan M

    2007-02-01

    Here, we present a simple stiff-limbed passive model of quadrupedal walking, compare mechanics predicted from the model with those observed from forceplate measurements of walking dogs and consider the implications of deviation from model predictions, especially with reference to collision mechanics. The model is based on the geometry of a 4-bar linkage consisting of a stiff hindleg, back, foreleg and the ground between the hind and front feet. It uses empirical morphological and kinematic inputs to determine the fluctuations in potential and kinetic energy, vertical and horizontal forces and energy losses associated with inelastic collisions at each foot placement. Using forceplate measurements to calculate centre of mass motions of walking dogs, we find that (1) dogs may, but are not required to, spend periods of double support (one hind- and one forefoot) agreeing with the passive model; (2) legs are somewhat compliant, and mechanical energy fluctuates during triple support, with mechanical energy being lost directly after hindfoot placement and replaced following forefoot placement. Footfall timings and timing of mechanical energy fluctuations are consistent with strategies to reduce collisional forces, analogous to the suggested role of ankle extension as an efficient powering mechanism in human walking.

  19. Ankle blood pressure as a predictor of total and cardiovascular mortality

    Science.gov (United States)

    Hietanen, Heikki; Pääkkönen, Rauni; Salomaa, Veikko

    2008-01-01

    Background The ankle blood pressure is commonly used as a ratio to the brachial blood pressure, called ankle-brachial index (ABI). Very few studies have considered the independent value of the ankle blood pressure without indexing it to the brachial blood pressure. We examined the value of ankle blood pressure, together with the exercise blood pressure, as a predictor of cardiovascular (CVD) and total mortality. Methods A prospective follow-up study of 3,858 consecutive ambulatory patients (mean age 51 years, 65,9% male) referred to a symptom-limited exercise test between August 1989 and December 1995. The cohort was followed up for all-cause and CVD mortality until December 31, 2004, by record linkage with the National Causes-of-Death Register. The independent value of ankle blood pressure as a predictor of cardiovascular and total mortality was assessed using Cox proportional hazards modelling. Results The average follow-up time was 14 years, during which 346 persons died, 108 of them due to CVD. Persons with normal (<140 mmHg) resting brachial blood pressure, ankle blood pressure < 175 mmHg and exercise blood pressure at moderate exercise level ≤215 mmHg at baseline investigation, had the best prognosis and were taken as the reference category. Among persons with elevated ankle blood pressure (≥175 mmHg) but normal or borderline resting brachial pressure and normal exercise blood pressure (≤215 mmHg) at moderate exercise level the multivariate-adjusted hazard ratios (HR, 95% confidence interval) for CVD and total mortality were 2.70 (1.52 – 4.80) and 2.13 (1.58 – 2.85), respectively. Similar and equally significant HRs were observed in persons with both elevated ankle blood pressure and elevated exercise blood pressure, as well as in those persons with elevated exercise blood pressure but ankle blood pressure < 175 mmHg. Conclusion These results suggest that the ankle blood pressure has an independent value as a marker of arterial stiffness or

  20. Stiffness, resilience, compressibility

    Energy Technology Data Exchange (ETDEWEB)

    Leu, Bogdan M. [Argonne National Laboratory, Advanced Photon Source (United States); Sage, J. Timothy, E-mail: jtsage@neu.edu [Northeastern University, Department of Physics and Center for Interdisciplinary Research on Complex Systems (United States)

    2016-12-15

    The flexibility of a protein is an important component of its functionality. We use nuclear resonance vibrational spectroscopy (NRVS) to quantify the flexibility of the heme iron environment in the electron-carrying protein cytochrome c by measuring the stiffness and the resilience. These quantities are sensitive to structural differences between the active sites of different proteins, as illustrated by a comparative analysis with myoglobin. The elasticity of the entire protein, on the other hand, can be probed quantitatively from NRVS and high energy-resolution inelastic X-ray scattering (IXS) measurements, an approach that we used to extract the bulk modulus of cytochrome c.

  1. Explosive Resistance Training Increases Rate of Force Development in Ankle Dorsiflexors and Gait Function in Adults With Cerebral Palsy.

    Science.gov (United States)

    Kirk, Henrik; Geertsen, Svend S; Lorentzen, Jakob; Krarup, Kasper B; Bandholm, Thomas; Nielsen, Jens B

    2016-10-01

    Kirk, H, Geertsen, SS, Lorentzen, J, Krarup, KB, Bandholm, T, and Nielsen, JB. Explosive resistance training increases rate of force development in ankle dorsiflexors and gait function in adults with cerebral palsy. J Strength Cond Res 30(10): 2749-2760, 2016-Alterations in passive elastic properties of muscles and reduced ability to quickly generate muscle force contribute to impaired gait function in adults with cerebral palsy (CP). In this study, we investigated whether 12 weeks of explosive and progressive heavy-resistance training (PRT) increases rate of force development of ankle dorsiflexors (RFDdf), improves gait function, and affects passive ankle joint stiffness in adults with CP. Thirty-five adults (age: 36.5; range: 18-59 years) with CP were nonrandomly assigned to a PRT or nontraining control (CON) group in this explorative trial. The PRT group trained ankle dorsiflexion, plantarflexion, leg press, hamstring curls, abdominal curls, and back extension 3 days per week for 12 weeks, with 3 sets per exercise and progressing during the training period from 12 to 6 repetition maximums. RFDdf, 3-dimensional gait analysis, functional performance, and ankle joint passive and reflex-mediated muscle stiffness were evaluated before and after. RFDdf increased significantly after PRT compared to CON. PRT also caused a significant increase in toe lift late in swing and a significantly more dorsiflexed ankle joint at ground contact and during stance. The increased toe-lift amplitude was correlated to the increased RFDdf (r = 0.73). No other between-group differences were observed. These findings suggest that explosive PRT may increase RFDdf and facilitate larger range of movement in the ankle joint during gait. Explosive PRT should be tested in clinical practice as part of a long-term training program for adults with CP.

  2. Paired changes in electromechanical delay and musculo-tendinous stiffness after endurance or plyometric training.

    Science.gov (United States)

    Grosset, Jean-Francois; Piscione, Julien; Lambertz, Daniel; Pérot, Chantal

    2009-01-01

    When measured in vivo electromechanical delay (EMD) depends mainly on the elastic properties of the muscle-tendon unit. Recent studies have shown changes in stiffness of the triceps surae (TS) following a period of training. To confirm the influence of musculo-tendinous stiffness on EMD, this study investigates paired changes in these two parameters after a training period. Two types of training known to induce opposite changes in stiffness were analysed. EMD and musculo-tendinous stiffness were measured on adult subjects before and after 10 weeks of endurance (n = 21) or plyometric (n = 9) trainings. EMD was defined as the time lag between the TS M-wave latency and the onset of muscle twitch evoked at rest by supramaximal electrical stimulations of the posterior tibial nerve. Quick release tests were used to evaluate the musculo-tendinous stiffness of the ankle plantar flexors. The stiffness index was defined as the slope of the relationship between angular stiffness and external torque values. Endurance training, known to preferentially activate the slow, stiffer muscle fibers, leads to a decrease in EMD and to an increase in stiffness index. Following plyometric training, which specifically recruits fast, more compliant fibers, EMD and the stiffness index exhibited adaptations directionally opposite to those seen with endurance training. When pooling the data for the two subject groups, a correlation was found between changes in EMD and changes in musculo-tendinous stiffness indexes. Thus, changes in EMD values are proposed to indirectly link to changes in musculo-tendinous stiffness for subjects involved in muscle training.

  3. Leg and Joint Stiffness in Children with Spastic Diplegic Cerebral Palsy during Level Walking.

    Directory of Open Access Journals (Sweden)

    Ting-Ming Wang

    Full Text Available Individual joint deviations are often identified in the analysis of cerebral palsy (CP gait. However, knowledge is limited as to how these deviations affect the control of the locomotor system as a whole when striving to meet the demands of walking. The current study aimed to bridge the gap by describing the control of the locomotor system in children with diplegic CP in terms of their leg stiffness, both skeletal and muscular components, and associated joint stiffness during gait. Twelve children with spastic diplegia CP and 12 healthy controls walked at a self-selected pace in a gait laboratory while their kinematic and forceplate data were measured and analyzed during loading response, mid-stance, terminal stance and pre-swing. For calculating the leg stiffness, each of the lower limbs was modeled as a non-linear spring, connecting the hip joint center and the corresponding center of pressure, with varying stiffness that was calculated as the slope (gradient of the axial force vs. the deformation curve. The leg stiffness was further decomposed into skeletal and muscular components considering the alignment of the lower limb. The ankle, knee and hip of the limb were modeled as revolute joints with torsional springs whose stiffness was calculated as the slope of the moment vs. the angle curve of the joint. Independent t-tests were performed for between-group comparisons of all the variables. The CP group significantly decreased the leg stiffness but increased the joint stiffness during stance phase, except during terminal stance where the leg stiffness was increased. They appeared to rely more on muscular contributions to achieve the required leg stiffness, increasing the muscular demands in maintaining the body posture against collapse. Leg stiffness plays a critical role in modulating the kinematics and kinetics of the locomotor system during gait in the diplegic CP.

  4. Hydrocolonotherapy ankle joints after injuries

    Directory of Open Access Journals (Sweden)

    Volodymyr Muchin

    2016-02-01

    Full Text Available Purpose: to improve efficiency of gydrokinesitherapy by means of specially designed devices and monolasts for patients after ankle joint injuries. Material & Methods: there are pedagogical methods, clinical and radiological methods, anthropometric measurements and goniometry were used. Results: the author's technique of hydrokinesitherapy with application hydrokinesimechanotherapy device in the program of physical rehabilitation which provides optimum conditions for the recovery process was developed. Conclusions: the specially designed hydrokinesomechanotherapeutic device and monolasts are allow strictly controlled movement in all planes of the ankle joint, which contributes to the acceleration of the recovery; the conducted anthropometric and goniometric studies were indicate more rapid elimination of edema, increase movement amplitude, carries opposition to the development of contractures and muscle atrophy.

  5. Annular lipoatrophy of the ankles.

    Science.gov (United States)

    Dimson, Otobia G; Esterly, Nancy B

    2006-02-01

    Lipoatrophic panniculitis likely represents a group of disorders characterized by an inflammatory panniculitis followed by lipoatrophy. It occurs locally in a variety of settings and has been reported in the literature under various terms, including annular atrophic connective tissue panniculitis of the ankles, annular and semicircular lipoatrophy, abdominal lipoatrophy, and connective tissue panniculitis. Herein, a case of annular lipoatrophy of the ankles is described in a 6-year-old girl with autoimmune thyroid disease. Histologically, a mixed lobular panniculitis with lipophages was present. This pattern resembles that seen in lipoatrophic panniculitis. After a single, acute episode of an inflammatory process with subsequent lipoatrophy, her skin lesions have stabilized for 2 years requiring no treatment.

  6. Hydrocolonotherapy ankle joints after injuries

    OpenAIRE

    Volodymyr Muchin; Oleksandr Zviriaka

    2016-01-01

    Muchin V., Zviriaka O. Purpose: to improve efficiency of gydrokinesitherapy by means of specially designed devices and monolasts for patients after ankle joint injuries. Material & Methods: there are pedagogical methods, clinical and radiological methods, anthropometric measurements and goniometry were used. Results: the author's technique of hydrokinesitherapy with application hydrokinesimechanotherapy device in the program of physical rehabilitation which provides optimum conditions for...

  7. Reliability of metatarsophalangeal and ankle joint torque measurements by an innovative device.

    Science.gov (United States)

    Man, Hok-Sum; Leung, Aaron Kam-Lun; Cheung, Jason Tak-Man; Sterzing, Thorsten

    2016-07-01

    The toe flexor muscles maintain body balance during standing and provide push-off force during walking, running, and jumping. Additionally, they are important contributing structures to maintain normal foot function. Thus, weakness of these muscles may cause poor balance, inefficient locomotion and foot deformities. The quantification of metatarsophalangeal joint (MPJ) stiffness is valuable as it is considered as a confounding factor in toe flexor muscles function. MPJ and ankle joint stiffness measurement is still largely depended on manual skills as current devices do not have good control on alignment, angular joint speed and displacement during measurement. Therefore, this study introduces an innovative dynamometer and protocol procedures for MPJ and ankle Joint torque measurement with precise and reliable foot alignment, angular joint speed and displacement control. Within-day and between-day test-retest experiments on MPJ and ankle joint torque measurement were conducted on ten and nine healthy male subjects respectively. The mean peak torques of MPJ and ankle joint of between-day and within-day measurement were 1.50±0.38Nm/deg and 1.19±0.34Nm/deg. The corresponding torques of the ankle joint were 8.24±2.20Nm/deg and 7.90±3.18Nm/deg respectively. Intraclass-correlation coefficients (ICC) of averaged peak torque of both joints of between-day and within-day test-retest experiments were ranging from 0.91 to 0.96, indicating the innovative device is systematic and reliable for the measurements and can be used for multiple scientific and clinical purposes.

  8. Biomaterial arrays with defined adhesion ligand densities and matrix stiffness identify distinct phenotypes for tumorigenic and nontumorigenic human mesenchymal cell types

    OpenAIRE

    Hansen, Tyler D.; Koepsel, Justin T.; Le, Ngoc Nhi; Nguyen, Eric H.; Zorn, Stefan; Parlato, Matthew; Loveland, Samuel G.; Schwartz, Michael P.; Murphy, William L.

    2014-01-01

    Here, we aimed to investigate migration of a model tumor cell line (HT-1080 fibrosarcoma cells, HT-1080s) using synthetic biomaterials to systematically vary peptide ligand density and substrate stiffness. A range of substrate elastic moduli were investigated by using poly(ethylene glycol) (PEG) hydrogel arrays (0.34 - 17 kPa) and self-assembled monolayer (SAM) arrays (~0.1-1 GPa), while cell adhesion was tuned by varying the presentation of Arg-Gly-Asp (RGD)-containing peptides. HT-1080 moti...

  9. Total Ankle Arthroplasty: A Brief Review

    Directory of Open Access Journals (Sweden)

    Roger A. Mann

    2012-12-01

    Full Text Available Ankle fusion has long been the standard of treatment for end-stage ankle arthritis, and a successful arthroplasty has been a long sought alternative. It is a motion sparing procedure and may greatly reduce the potential for adjacent level degeneration as seen with arthrodesis. The typical candidate for arthroplasty is a healthy low demand patient, although the indications are widening as the success of the procedure has increased. Nevertheless, it is not fail-safe, technical expertise and experience are necessary to achieve a successful result. We have been treating ankle arthritis with the Scandinavian Total Ankle Replacement (STAR ankle replacement prosthesis for over ten years. We believe that arthroplasty will surpass arthrodesis as the standard of care for severe ankle arthritis.

  10. Imaging findings in arthrofibrosis of the ankle and foot.

    Science.gov (United States)

    Linklater, James M; Fessa, Chris K

    2012-07-01

    Arthrofibrosis is defined as joint pain and stiffness that does not allow functional range of motion and is due to adhesions or contracture of the joint. Arthrofibrosis is characterized by an abnormal proliferation of fibrous tissue that may be focal or diffuse and intra-articular or extra-articular. Trauma and surgery are the most common etiological factors. In the ankle and foot symptomatic arthrofibrosis is not uncommonly seen in the talocrural joint, posterior subtalar joint, and the metatarsophalangeal joints. Imaging can assist with diagnosis and planning treatment, most commonly using MRI and occasionally ultrasound. Typical imaging findings consist of capsular and pericapsular thickening and scarring, best demonstrated on proton-density MR images but also demonstrable on ultrasound. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  11. Outcome of ankle arthrodesis in posttraumatic arthritis

    Directory of Open Access Journals (Sweden)

    B S Narayana Gowda

    2012-01-01

    Full Text Available Background: Ankle arthrodesis is still a gold standard salvage procedure for the management of ankle arthritis. There are several functional and mechanical benefits of ankle arthrodesis, which make it a viable surgical procedure in the management of ankle arthritis. The functional outcomes following ankle arthrodesis are not very well known. The purpose of this study was to perform a clinical and radiographic evaluation of ankle arthrodesis in posttraumatic arthritis performed using Charnley′s compression device. Materials and Methods: Between January 2006 and December 2009 a functional assessment of 15 patients (10 males and 5 females who had undergone ankle arthrodesis for posttraumatic arthritis and/or avascular necrosis (AVN talus (n=6, malunited bimalleolar fracture (n=4, distal tibial plafond fractures (n=3, medial malleoli nonunion (n=2. All the patients were assessed clinically and radiologically after an average followup of 2 years 8 months (range 1-5.7 years. Results: All patients had sound ankylosis and no complications related to the surgery. Scoring the patients with the American Orthopaedic Foot and Ankle Society (AOFAS Ankle-Hindfoot scale, we found that 11 of the 15 had excellent results, two had good, and two showed fair results. They were all returned to their preinjury activities. Conclusion: We conclude that, the ankle arthrodesis can still be considered as a standard procedure in ankle arthritis. On the basis of these results, patients should be counseled that an ankle fusion will help to relieve pain and to improve overall function. Still, one should keep in mind that it is a salvage procedure that will cause persistent alterations in gait with a potential for deterioration due to the development of subtalar arthritis.

  12. Clinical application of a modular ankle robot for stroke rehabilitation

    Science.gov (United States)

    Forrester, Larry W.; Roy, Anindo; Goodman, Ronald N.; Rietschel, Jeremy; Barton, Joseph E.; Krebs, Hermano Igo; Macko, Richard F.

    2015-01-01

    Background Advances in our understanding of neuroplasticity and motor learning post-stroke are now being leveraged with the use of robotics technology to enhance physical rehabilitation strategies. Major advances have been made with upper extremity robotics, which have been tested for efficacy in multi-site trials across the subacute and chronic phases of stroke. In contrast, use of lower extremity robotics to promote locomotor re-learning has been more recent and presents unique challenges by virtue of the complex multi-segmental mechanics of gait. Objectives Here we review a programmatic effort to develop and apply the concept of joint-specific modular robotics to the paretic ankle as a means to improve underlying impairments in distal motor control that may have a significant impact on gait biomechanics and balance. Methods An impedance controlled ankle robot module (anklebot) is described as a platform to test the idea that a modular approach can be used to modify training and measure the time profile of treatment response. Results Pilot studies using seated visuomotor anklebot training with chronic patients are reviewed, along with results from initial efforts to evaluate the anklebot's utility as a clinical tool for assessing intrinsic ankle stiffness. The review includes a brief discussion of future directions for using the seated anklebot training in the earliest phases of sub-acute therapy, and to incorporate neurophysiological measures of cerebro-cortical activity as a means to reveal underlying mechanistic processes of motor learning and brain plasticity associated with robotic training. Conclusions Finally we conclude with an initial control systems strategy for utilizing the anklebot as a gait training tool that includes integrating an Internal Model-based adaptive controller to both accommodate individual deficit severities and adapt to changes in patient performance. PMID:23949045

  13. Clinical application of a modular ankle robot for stroke rehabilitation.

    Science.gov (United States)

    Forrester, Larry W; Roy, Anindo; Goodman, Ronald N; Rietschel, Jeremy; Barton, Joseph E; Krebs, Hermano Igo; Macko, Richard F

    2013-01-01

    Advances in our understanding of neuroplasticity and motor learning post-stroke are now being leveraged with the use of robotics technology to enhance physical rehabilitation strategies. Major advances have been made with upper extremity robotics, which have been tested for efficacy in multi-site trials across the subacute and chronic phases of stroke. In contrast, use of lower extremity robotics to promote locomotor re-learning has been more recent and presents unique challenges by virtue of the complex multi-segmental mechanics of gait. Here we review a programmatic effort to develop and apply the concept of joint-specific modular robotics to the paretic ankle as a means to improve underlying impairments in distal motor control that may have a significant impact on gait biomechanics and balance. An impedance controlled ankle robot module (anklebot) is described as a platform to test the idea that a modular approach can be used to modify training and measure the time profile of treatment response. Pilot studies using seated visuomotor anklebot training with chronic patients are reviewed, along with results from initial efforts to evaluate the anklebot's utility as a clinical tool for assessing intrinsic ankle stiffness. The review includes a brief discussion of future directions for using the seated anklebot training in the earliest phases of sub-acute therapy, and to incorporate neurophysiological measures of cerebro-cortical activity as a means to reveal underlying mechanistic processes of motor learning and brain plasticity associated with robotic training. Finally we conclude with an initial control systems strategy for utilizing the anklebot as a gait training tool that includes integrating an Internal Model-based adaptive controller to both accommodate individual deficit severities and adapt to changes in patient performance.

  14. Biomechanical consequences of gait impairment at the ankle and foot : Injury, malalignment, and co-contraction

    OpenAIRE

    Wang, Ruoli

    2012-01-01

    The human foot contributes significantly to the function of the whole lower extremity during standing and locomotion. Nevertheless, the foot and ankle often suffer injuries and are affected by many musculoskeletal and neurological pathologies. The overall aim of this thesis was to evaluate gait parameters and muscle function change due to foot and ankle injury, malalignment and co-contraction. Using 3D gait analysis, analytical analyses and computational simulations, biomechanical consequence...

  15. Total ankle arthroplasty: An imaging overview

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Da Rae; Choi, Yun Sun; Chun, Ka Young; Jung, Yoon Young; Kim, Jin Su; Young, Ki Won [Eulji Hospital, Eulji University, Seoul (Korea, Republic of); Potter, Hollis G.; Li, Angela E. [Dept. of Radiology and Imaging, Hospital for Special Surgery, New York (United States)

    2016-06-15

    With advances in implant technology, total ankle arthroplasty (TAA) has become an increasingly popular alternative to arthrodesis for the management of end-stage ankle arthritis. However, reports in the literature do not focus on the imaging features of TAA. Through a literature review, we demonstrate basic design features of the current ankle arthroplasty system, and the normal and abnormal postoperative imaging features associated with such devices. Pre- and postoperative evaluations of ankle arthroplasty mainly include radiography; in addition, computed tomography and magnetic resonance imaging provide further characterization of imaging abnormalities. Familiarization with multimodal imaging features of frequent procedural complications at various postoperative intervals is important in radiological practice.

  16. Total Ankle Arthroplasty: An Imaging Overview.

    Science.gov (United States)

    Kim, Da-Rae; Choi, Yun Sun; Potter, Hollis G; Li, Angela E; Chun, Ka-Young; Jung, Yoon Young; Kim, Jin-Su; Young, Ki-Won

    2016-01-01

    With advances in implant technology, total ankle arthroplasty (TAA) has become an increasingly popular alternative to arthrodesis for the management of end-stage ankle arthritis. However, reports in the literature do not focus on the imaging features of TAA. Through a literature review, we demonstrate basic design features of the current ankle arthroplasty system, and the normal and abnormal postoperative imaging features associated with such devices. Pre- and postoperative evaluations of ankle arthroplasty mainly include radiography; in addition, computed tomography and magnetic resonance imaging provide further characterization of imaging abnormalities. Familiarization with multimodal imaging features of frequent procedural complications at various postoperative intervals is important in radiological practice.

  17. Fusion following failed total ankle replacement.

    Science.gov (United States)

    Wünschel, Markus; Leichtle, Ulf G; Leichtle, Carmen I; Walter, Christian; Mittag, Falk; Arlt, Eva; Suckel, Andreas

    2013-04-01

    Although mid- to long-term results after total ankle replacement have improved because of available second- and third-generation devices, failure of total ankle replacement is still more common compared with total hip replacement and total knee replacement. The portfolio of available total ankle replacement revision component options is small. Furthermore, the bone stock of the tibiotalar region is scarce making it difficult and in some situations impossible to perform revision total ankle replacement. In these cases tibiotalar and tibiotalocalcaneal fusions are valuable options. This article describes which surgical procedures should be performed depending on the initial situation and gives detailed advice on surgical technique, postoperative care, and clinical results.

  18. Maisonneuve-hyperplantarflexion variant ankle fracture.

    Science.gov (United States)

    Hinds, Richard M; Tran, Wesley H; Lorich, Dean G

    2014-11-01

    Maisonneuve fractures are rare ankle injuries, accounting for up to 7% of all ankle fractures. They consist of a proximal third fibula fracture, syndesmotic disruption, and medial ankle injury (either a deltoid ligament disruption or a medial malleolus fracture), and are often successfully managed with nonoperative treatment of the proximal fibula fracture and open reduction and internal fixation (ORIF) of the medial ankle injury and syndesmotic disruption. The hyperplantarflexion variant ankle fracture comprises approximately 7% of all ankle fractures and features dual posterior tibial lip fractures featuring a posterolateral fragment and a posteromedial fragment. Good functional results have been reported in the literature after ORIF of both the posterolateral and posteromedial fragments of this variant fracture that is not described by the Lauge-Hansen classification. In this report, the authors present the unique case of an isolated ankle fracture demonstrating characteristics of both a Maisonneuve fracture and a hyperplantarflexion variant ankle fracture. They also highlight the diagnostic imaging characteristics, including magnetic resonance imaging (MRI) and preoperative radiograph findings, surgical treatment, and postoperative clinical outcome for this patient with a Maisonneuve-hyperplantarflexion variant ankle fracture. To the authors' knowledge, this unique fracture pattern has not been reported previously in the literature. The authors conclude that although good results were seen postoperatively in this case, the importance of ORIF of both the posteromedial and posterolateral fragments of variant fractures cannot be overstated. They also found MRI to be a particularly helpful adjunct in formulating the correct diagnosis and treatment plan.

  19. Find an Orthopaedic Foot and Ankle MD/DO

    Science.gov (United States)

    ... Content AOFAS / FootCareMD / Find a Surgeon Find an Orthopaedic Foot & Ankle Surgeon Page Content The Orthopaedic Distinction Who are Orthopaedic Foot & Ankle Surgeons? Orthopaedic foot and ankle surgeons ...

  20. Finite element micro-modelling of a human ankle bone reveals the importance of the trabecular network to mechanical performance: new methods for the generation and comparison of 3D models.

    Science.gov (United States)

    Parr, W C H; Chamoli, U; Jones, A; Walsh, W R; Wroe, S

    2013-01-04

    Most modelling of whole bones does not incorporate trabecular geometry and treats bone as a solid non-porous structure. Some studies have modelled trabecular networks in isolation. One study has modelled the performance of whole human bones incorporating trabeculae, although this required considerable computer resources and purpose-written code. The difference between mechanical behaviour in models that incorporate trabecular geometry and non-porous models has not been explored. The ability to easily model trabecular networks may shed light on the mechanical consequences of bone loss in osteoporosis and remodelling after implant insertion. Here we present a Finite Element Analysis (FEA) of a human ankle bone that includes trabecular network geometry. We compare results from this model with results from non-porous models and introduce protocols achievable on desktop computers using widely available softwares. Our findings show that models including trabecular geometry are considerably stiffer than non-porous whole bone models wherein the non-cortical component has the same mass as the trabecular network, suggesting inclusion of trabecular geometry is desirable. We further present new methods for the construction and analysis of 3D models permitting: (1) construction of multi-property, non-porous models wherein cortical layer thickness can be manipulated; (2) maintenance of the same triangle network for the outer cortical bone surface in both 3D reconstruction and non-porous models allowing exact replication of load and restraint cases; and (3) creation of an internal landmark point grid allowing direct comparison between 3D FE Models (FEMs).

  1. Effects of weight loss and insulin reduction on arterial stiffness in the SAVE trial

    Directory of Open Access Journals (Sweden)

    Hughes Timothy M

    2012-09-01

    Full Text Available Abstract Background Chronic arterial stiffness contributes to the negative health effects of obesity and insulin resistance, which include hypertension, stroke, and increased cardiovascular and all-cause mortality. Weight loss and improved insulin sensitivity are individually associated with improved central arterial stiffness; however, their combined effects on arterial stiffness are poorly understood. The purpose of this study was to determine how insulin levels modify the improvements in arterial stiffness seen with weight loss in overweight and obese young adults. Methods To assess the effects of weight loss and decreased fasting insulin on vascular stiffness, we studied 339 participants in the Slow the Adverse Effects of Vascular Aging (SAVE trial. At study entry, the participants were aged 20–45, normotensive, non-diabetic, and had a body-mass index of 25–39.9 kg/m2. Measures of pulse wave velocity (PWV in the central (carotid-femoral (cfPWV, peripheral (femoral-ankle (faPWV, and mixed (brachial-ankle (baPWV vascular beds were collected at baseline and 6 months. The effects of 6-month change in weight and insulin on measures of PWV were estimated using multivariate regression. Results After adjustment for baseline risk factors and change in systolic blood pressure, 6-month weight loss and 6-month change in fasting insulin independently predicted improvement in baPWV but not faPWV or cfPWV. There was a significant interaction between 6-month weight change and change in fasting insulin when predicting changes in baPWV (p baPWV. Conclusions Young adults with excess weight who both lower their insulin levels and lose weight see the greatest improvement in vascular stiffness. This improvement in vascular stiffness with weight loss and insulin declines may occur throughout the vasculature and may not be limited to individual vascular beds. Trial registration NCT00366990

  2. Arterial Stiffness in Nonhypertensive Type 2 Diabetes Patients in Ghana

    Science.gov (United States)

    Antwi, Daniel A.; Gyan, Ben

    2016-01-01

    Background. Increased arterial stiffness is an independent cardiovascular risk factor in diabetes patients and general population. However, the contribution of diabetes to arterial stiffness is often masked by coexistent obesity and hypertension. In this study, we assessed arterial stiffness in nonhypertensive, nonobese type 2 diabetes (T2DM) patients in Ghana. Methods. In case-control design, 166 nonhypertensive, nonobese participants, comprising 96 T2DM patients and 70 nondiabetes controls, were recruited. Peripheral and central blood pressure (BP) indices were measured, and arterial stiffness was assessed as aortic pulse wave velocity (PWVao), augmentation index (AIx), cardioankle vascular index (CAVI), and heart-ankle pulse wave velocity (haPWV). Results. With similar peripheral and central BP indices, T2DM patients had higher PWVao (8.3 ± 1 versus 7.8 ± 1.3, p = 0.044) and CAVI (7.9 ± 1.2 versus 6.9 ± 0.7, p = 0.021) than nondiabetic control. AIx and haPWV were similar between T2DM and nondiabetic controls. Multiple regression models showed that, in the entire study participants, the major determinants of PWVao were diabetes status, age, gender, systolic BP, and previous smoking status (β = 0.22, 0.36, 0.48, 0.21, and 0.25, resp.; all p < 0.05); the determinants of CAVI were diabetes status, age, BMI, heart rate, HbA1c, total cholesterol, HDL cholesterol, and previous smoking status (β = 0.21, 0.38, 0.2, 0.18, 0.24. 0.2, −0.19, and 0.2, resp.; all p < 0.05). Conclusion. Our findings suggest that nonhypertensive, nonobese T2DM patients have increased arterial stiffness without appreciable increase in peripheral and central pressure indices.

  3. Passive mechanical properties of gastrocnemius muscles of people with ankle contracture after stroke.

    Science.gov (United States)

    Kwah, Li Khim; Herbert, Robert D; Harvey, Lisa A; Diong, Joanna; Clarke, Jillian L; Martin, Joshua H; Clarke, Elizabeth C; Hoang, Phu D; Bilston, Lynne E; Gandevia, Simon C

    2012-07-01

    To investigate the mechanisms of contracture after stroke by comparing passive mechanical properties of gastrocnemius muscle-tendon units, muscle fascicles, and tendons in people with ankle contracture after stroke with control participants. Cross-sectional study. Laboratory in a research institution. A convenience sample of people with ankle contracture after stroke (n=20) and able-bodied control subjects (n=30). Not applicable. Stiffness and lengths of gastrocnemius muscle-tendon units, lengths of muscle fascicles, and tendons at specific tensions. At a tension of 100N, the gastrocnemius muscle-tendon unit was significantly shorter in participants with stroke (mean, 436mm) than in able-bodied control participants (mean, 444mm; difference, 8mm; 95% confidence interval [CI], 0.2-15mm; P=.04). Muscle fascicles were also shorter in the stroke group (mean, 44mm) than in the control group (mean, 50mm; difference, 6mm; 95% CI, 1-12mm; P=.03). There were no significant differences between groups in the mean stiffness or length of the muscle-tendon units and fascicles at low tension, or in the mean length of the tendons at any tension. People with ankle contracture after stroke have shorter gastrocnemius muscle-tendon units and muscle fascicles than control participants at high tension. This difference is not apparent at low tension. Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  4. Current concepts review: ankle fractures.

    Science.gov (United States)

    Arastu, M H; Demcoe, R; Buckley, R E

    2012-01-01

    Ankle fractures are common injuries that require meticulous technique in order to optimise outcome. The Lauge-Hansen and Danis-Weber classifications in addition to careful evaluation of the injury mechanism can help guide treatment but surgeons must be aware that there are injury patterns that will not always fit the afore mentioned patterns. The principles of atraumatic soft tissue handling, rigid internal fixation and early range of motion exercises are critical for successfully treating these injuries. There are still areas of treatment uncertainty and future directed research is needed in order to address some of these questions.

  5. Haemophilic arthropathy of the ankle treated by total ankle replacement: a case series.

    Science.gov (United States)

    Barg, A; Elsner, A; Hefti, D; Hintermann, B

    2010-07-01

    The standard treatment for end-stage osteoarthritis of the ankle joint in haemophilic patients has been fusion of the ankle joint. Total ankle replacement is still controversial as a treatment option. The objective of this prospective study was to evaluate the mid-term outcome in patients treated with total ankle replacement using an unconstrained three-component ankle implant. Ten haemophilic ankles in eight patients (mean age: 43.2 years, range 26.7-57.5) treated with total ankle replacement were followed up for a minimum of 2.7 years (mean: 5.6, range 2.7-7.6). The outcome was measured with clinical and radiological evaluations. There were no intra- or peri-operative complications. The AOFAS-hindfoot-score increased from 38 (range 8-57) preoperatively to 81 (range 69-95) postoperatively. All patients were satisfied with the results. Four patients became pain free; in the whole patient cohort pain level decreased from 7.1 (range 4-9) preoperatively to 0.8 (range 0-3) postoperatively. All categories of SF-36 score showed significant improvements in quality of life. In one patient, open ankle arthrolysis was performed because of painful arthrofibrosis. For patients with haemophilic osteoarthritis of the ankle joint, total ankle replacement is a valuable alternative treatment to ankle fusion.

  6. Radiological aspects of sprained ankle syndrome

    NARCIS (Netherlands)

    Sijbrandij, E.S.

    2002-01-01

    This thesis addresses several problems related to sprained ankle syndrome. The purpose of this thesis is to evaluate the imaging features of sprained ankles, found on new radiological modalities, and to assess the additional diagnostic understanding and treatment planning of helical CT as well as M

  7. Assessment of acute foot and ankle sprains.

    Science.gov (United States)

    Lynam, Louise

    2006-07-01

    Acute ankle and foot trauma is a regular emergency presentation and prompt strategic assessment skills are required to enable nurses to categorise and prioritise these injuries appropriately. This article provides background information on the anatomy and physiology of the lower limb to help nurses to identify various grades of ankle sprain as well as injuries that are limb threatening

  8. Osteochondral defects in the ankle: why painful?

    NARCIS (Netherlands)

    van Dijk, C.N.; Reilingh, M.L.; Zengerink, M.; van Bergen, C.J.A.

    2010-01-01

    Osteochondral defects of the ankle can either heal and remain asymptomatic or progress to deep ankle pain on weight bearing and formation of subchondral bone cysts. The development of a symptomatic OD depends on various factors, including the damage and insufficient repair of the subchondral bone pl

  9. Osteochondral defects in the ankle: why painful?

    NARCIS (Netherlands)

    van Dijk, C.N.; Reilingh, M.L.; Zengerink, M.; van Bergen, C.J.A.

    2010-01-01

    Osteochondral defects of the ankle can either heal and remain asymptomatic or progress to deep ankle pain on weight bearing and formation of subchondral bone cysts. The development of a symptomatic OD depends on various factors, including the damage and insufficient repair of the subchondral bone pl

  10. Influence of simulated microgravity on mechanical properties in the human triceps surae muscle in vivo. I: effect of 120 days of bed-rest without physical training on human muscle musculo-tendinous stiffness and contractile properties in young women.

    Science.gov (United States)

    Koryak, Yuri A

    2014-05-01

    The aim of this study was to investigate the effect of a 120-day 5° head-down tilt (HDT) bed-rest on the mechanical properties of the human triceps surae muscle in healthy young women subjects. Measurements included examination of the properties of maximal voluntary contractions (MVC), twitch contractions (P t) and tetanic contractions (P o). The difference between P o and MVC expressed as a percentage of P o and referred to as force deficiency (P d), was calculated. Electromyographic (EMG) activity in the soleus muscle, electromechanical delay (EMD) and total reaction time (TRT) were also calculated. EMD was the time interval between the change in EMG and the onset of muscle tension. Premotor time (PMT) was taken to be the time interval from the delivery of the signal to change in EMG. After HDT P t, MVC and P o had decreased by 11.5, 36.1, 24.4 %, respectively, P d had increased by 38.8 %. Time-to-peak tension had increased by 13.6 %, but half-relaxation time had decreased by 19.2 %. The rate of rise in isometric voluntary tension development had reduced, but no changes were observed in the electrically evoked contraction. EMD had increased by 27.4 %; PMT and TRT decreased by 21.4, and 13.7 %, respectively. The experimental findings indicated that neural as well as muscle adaptation occurred in response to HDT. EMD is a simple and quick method for evaluation of muscle stiffness changes and can serve as an indicator of the functional condition of the neuromuscular system.

  11. Total ankle replacement - surgical treatment and rehabilitation.

    Science.gov (United States)

    Prusinowska, Agnieszka; Krogulec, Zbigniew; Turski, Piotr; Przepiórski, Emil; Małdyk, Paweł; Księżopolska-Orłowska, Krystyna

    2015-01-01

    Functions of the ankle joint are closely connected with the gait and ability to maintain an upright position. Degenerative lesions of the joint directly contribute to postural disorders and greatly restrict propulsion of the foot, thus leading to abnormal gait. Development of total ankle replacement is connected with the use of the method as an efficient treatment of joint injuries and continuation of achievements in hip and knee surgery. The total ankle replacement technique was introduced as an alternative to arthrodesis, i.e. surgical fixation, which made it possible to preserve joint mobility and to improve gait. Total ankle replacement is indicated in post-traumatic degenerative joint disease and joint destruction secondary to rheumatoid arthritis. In this paper, total ankle replacement and various types of currently used endoprostheses are discussed. The authors also describe principles of early postoperative rehabilitation as well as rehabilitation in the outpatient setting.

  12. Chinese Massage Therapy for Ankle Injury

    Institute of Scientific and Technical Information of China (English)

    CHEN Ming-xia; LI Nian-qun; HUANG Guo-qi

    2003-01-01

    Purpose: To explore the therapeutic methods and effects in the treatment of acute and chronic injuries of the ankle joint by Chinese massage therapy in combination with external application of Chinese herbal drugs and functional exercises. Methods: Totally, 36 cases of the patients with acute soft tissue injury, chronic soft tissue injury and post-fracture sequelae of the ankle joint were treated by Chinese massage therapy, external application or external wash of Chinese herbal drugs, and exercises of dorsal flexion and extension of the ankle joint, to observe the restoration of the ankle functions.Results: In 36 cases of the patients, the results showed remarkable effect in 18 cases, effect in 16 cases, failure in 2 cases and the effective rate in 94.4%. Conclusion: The combined use of Chinese massage therapy, external application of Chinese herbal drugs and functional exercises can produce precise effect in the treatment of soft tissue injury of the ankle joint.

  13. Assessment of the non-linear behaviour of plastic ankle foot orthoses by the finite element method

    OpenAIRE

    Syngellakis, S.; Arnold, M. A.; Rassoulian, H.

    2000-01-01

    The stiffness characteristics of plastic ankle foot orthoses (AFOs) are studied through finite element modelling and stress analysis. Particular attention is given to the modelling and prediction of non-linear AFO behaviour, which has been frequently observed in previous experimental studies but not fully addressed analytically. Both large deformation effects and material non-linearity are included in the formulation and their individual influence on results assessed. The finite element progr...

  14. A Reply to Stiff and Boster.

    Science.gov (United States)

    Petty, Richard E.; And Others

    1987-01-01

    Addresses the major errors and misconceptions perpetuated by Stiff and Boster's response to criticism of Stiff's 1986 article. Focuses on the major conceptual and methodological issues of Stiff's model. (NKA)

  15. The human foot and heel–sole–toe walking strategy: a mechanism enabling an inverted pendular gait with low isometric muscle force?

    Science.gov (United States)

    Usherwood, J. R.; Channon, A. J.; Myatt, J. P.; Rankin, J. W.; Hubel, T. Y.

    2012-01-01

    Mechanically, the most economical gait for slow bipedal locomotion requires walking as an ‘inverted pendulum’, with: I, an impulsive, energy-dissipating leg compression at the beginning of stance; II, a stiff-limbed vault; and III, an impulsive, powering push-off at the end of stance. The characteristic ‘M’-shaped vertical ground reaction forces of walking in humans reflect this impulse–vault–impulse strategy. Humans achieve this gait by dissipating energy during the heel-to-sole transition in early stance, approximately stiff-limbed, flat-footed vaulting over midstance and ankle plantarflexion (powering the toes down) in late stance. Here, we show that the ‘M’-shaped walking ground reaction force profile does not require the plantigrade human foot or heel–sole–toe stance; it is maintained in tip–toe and high-heel walking as well as in ostriches. However, the unusual, stiff, human foot structure—with ground-contacting heel behind ankle and toes in front—enables both mechanically economical inverted pendular walking and physiologically economical muscle loading, by producing extreme changes in mechanical advantage between muscles and ground reaction forces. With a human foot, and heel–sole–toe strategy during stance, the shin muscles that dissipate energy, or calf muscles that power the push-off, need not be loaded at all—largely avoiding the ‘cost of muscle force’—during the passive vaulting phase. PMID:22572024

  16. The human foot and heel-sole-toe walking strategy: a mechanism enabling an inverted pendular gait with low isometric muscle force?

    Science.gov (United States)

    Usherwood, J R; Channon, A J; Myatt, J P; Rankin, J W; Hubel, T Y

    2012-10-07

    Mechanically, the most economical gait for slow bipedal locomotion requires walking as an 'inverted pendulum', with: I, an impulsive, energy-dissipating leg compression at the beginning of stance; II, a stiff-limbed vault; and III, an impulsive, powering push-off at the end of stance. The characteristic 'M'-shaped vertical ground reaction forces of walking in humans reflect this impulse-vault-impulse strategy. Humans achieve this gait by dissipating energy during the heel-to-sole transition in early stance, approximately stiff-limbed, flat-footed vaulting over midstance and ankle plantarflexion (powering the toes down) in late stance. Here, we show that the 'M'-shaped walking ground reaction force profile does not require the plantigrade human foot or heel-sole-toe stance; it is maintained in tip-toe and high-heel walking as well as in ostriches. However, the unusual, stiff, human foot structure--with ground-contacting heel behind ankle and toes in front--enables both mechanically economical inverted pendular walking and physiologically economical muscle loading, by producing extreme changes in mechanical advantage between muscles and ground reaction forces. With a human foot, and heel-sole-toe strategy during stance, the shin muscles that dissipate energy, or calf muscles that power the push-off, need not be loaded at all--largely avoiding the 'cost of muscle force'--during the passive vaulting phase.

  17. Stiffness of desiccating insect wings

    Energy Technology Data Exchange (ETDEWEB)

    Mengesha, T E; Vallance, R R [Department of Mechanical Engineering, The George Washington University, 738 Phillips Hall, 801 22nd St NW, Washington, DC 20052 (United States); Mittal, R, E-mail: vallance@gwu.edu [Department of Mechanical Engineering, Johns Hopkins University, 126 Latrobe Hall, 3400 N Charles Street, Baltimore, MD 21218 (United States)

    2011-03-15

    The stiffness of insect wings is typically determined through experimental measurements. Such experiments are performed on wings removed from insects. However, the wings are subject to desiccation which typically leads to an increase in their stiffness. Although this effect of desiccation is well known, a comprehensive study of the rate of change in stiffness of desiccating insect wings would be a significant aid in planning experiments as well as interpreting data from such experiments. This communication presents a comprehensive experimental analysis of the change in mass and stiffness of gradually desiccating forewings of Painted Lady butterflies (Vanessa cardui). Mass and stiffness of the forewings of five butterflies were simultaneously measured every 10 min over a 24 h period. The averaged results show that wing mass declined exponentially by 21.1% over this time period with a time constant of 9.8 h, while wing stiffness increased linearly by 46.2% at a rate of 23.4 {mu}N mm{sup -1} h{sup -1}. For the forewings of a single butterfly, the experiment was performed over a period of 1 week, and the results show that wing mass declined exponentially by 52.2% with a time constant of 30.2 h until it reached a steady-state level of 2.00 mg, while wing stiffness increased exponentially by 90.7% until it reached a steady-state level of 1.70 mN mm{sup -1}. (communication)

  18. Cocoa intake and arterial stiffness in subjects with cardiovascular risk factors

    Directory of Open Access Journals (Sweden)

    Recio-Rodríguez José

    2012-02-01

    Full Text Available Abstract Background To analyze the relationship of cocoa intake to central and peripheral blood pressure, arterial stiffness, and carotid intima-media thickness in subjects with some cardiovascular risk factor. Findings Design: A cross-sectional study of 351 subjects (mean age 54.76 years, 62.4% males. Measurements: Intake of cocoa and other foods using a food frequency questionnaire, central and peripheral (ambulatory and office blood pressure, central and peripheral augmentation index, pulse wave velocity, ambulatory arterial stiffness index, carotid intima-media thickness, and ankle-brachial index. Results: Higher pulse wave velocity and greater cardiovascular risk were found in non-cocoa consumers as compared to high consumers (p Conclusions In subjects with some cardiovascular risk factors, cocoa consumption does not imply improvement in the arterial stiffness values. Trial Registration Clinical Trials.gov Identifier: NCT01325064.

  19. Analytical theory for shape stiffness

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The shape stiffness of mill m is defined as the crosswise rigidity of the unit width of steel plate, that is, m=k/b. By differentiating the steel plate crown equation in the vector model of steel plate shape, a new concise equation for the shape stiffness, kc=m+q, is obtained. Furthermore, by combining the calculation equation for steel plate crown derived from Castigliano's theorem, an analytical calculation equation for the shape rigidity of rolled steel plate is derived. The correctness and practicability of the theory for the shape stiffness are demonstrated by comparing the results from the numerical calculation with the practical data of a rolling mill.

  20. Analytical theory for shape stiffness

    Institute of Scientific and Technical Information of China (English)

    张进之

    2000-01-01

    The shape stiffness of mill m is defined as the crosswise rigidity of the unit width of steel plate, that is, m = k/b. By differentiating the steel plate crown equation in the vector model of steel plate shape, a new concise equation for the shape stiffness, kc = m + q, is obtained. Furthermore, by combining the calculation equation for steel plate crown derived from Castigliano’s theorem, an analytical calculation equation for the shape rigidity of rolled steel plate is derived. The correctness and practicability of the theory for the shape stiffness are demonstrated by comparing the results from the numerical calculation with the practical data of a rolling mill.

  1. Long sleep duration associated with a higher risk of increased arterial stiffness in males.

    Science.gov (United States)

    Tsai, Tsai-Chen; Wu, Jin-Shang; Yang, Yi-Ching; Huang, Ying-Hsiang; Lu, Feng-Hwa; Chang, Chih-Jen

    2014-08-01

    We aimed to examine the association between sleep duration and arterial stiffness among adults of different ages, because to date there has been only one study on this relationship, which was confined to middle-aged civil servants. Cross-sectional study. A health examination center in National Cheng Kung University Hospital, Taiwan. A total of 3,508 subjects, age 20-87 y, were enrolled after excluding those with a history of cerebrovascular events, coronary artery disease, peripheral artery disease, and taking lipid-lowering drugs, antihypertensives, hypoglycemic agents, and anti-inflammatory drugs, from October 2006 to August 2009. N/A. SLEEP DURATION WAS CLASSIFIED INTO THREE GROUPS: short ( 8 h). Arterial stiffness was measured by brachial-ankle pulse-wave velocity (baPWV), and increased arterial stiffness was defined as baPWV ≥ 1400 cm/sec. The sleep duration was different for subjects with and without increased arterial stiffness in males, but not in females. In the multivariate analysis for males, long sleepers (odds ratio [OR] 1.75, P = 0.034) but not short sleepers (OR 0.98, P = 0.92) had a higher risk of increased arterial stiffness. In addition, age, estimated glomerular filtration rate, hypertension, diabetes, total cholesterol/high-density lipoprotein cholesterol ratio, cigarette smoking, and exercise were also independently associated factors. However, in females, neither short nor long sleep duration was associated with increased arterial stiffness. Long sleep duration was associated with a higher risk of increased arterial stiffness in males. Short sleepers did not exhibit a significant risk of increased arterial stiffness in either sex. Tsai TC, Wu JS, Yang YC, Huang YH, Lu FH, Chang CJ. Long sleep duration associated with a higher risk of increased arterial stiffness in males. SLEEP 2014;37(8):1315-1320.

  2. Fabrication of Janus hydrogels with stiffness gradient using drop coalescence

    Science.gov (United States)

    Lee, Donghee; Golden, Kale; Ryu, Sangjin

    2016-11-01

    The stiffness of the extracellular matrix (ECM) regulates cellular behaviors, and polyacrylamide (PAAM) gels with stiffness gradient have been used to simulate inhomogeneous ECM and to study the effects of the ECM stiffness on cells. Such hydrogel substrates with stiffness gradient can be fabricated with relatively complicated methods using microfluidics and moving masks. In our study, we develop a simpler method for fabricating Janus hydrogel which has a gradient of stiffness. Two prepolymer solutions were prepared for soft and stiff gel compositions, respectively, and one drop of each solution was placed on a hydrophobic patterned glass. Then, these two drops were gently squeezed by another glass being slowly lowered until coalescence, and gel polymerization was initiated after a certain time period for mixing. The motion of the drops was guided by the hydrophobic pattern. AFM nano-indentation showed that the fabricated Janus PAAM gels have a stiffness gradient which could be controlled by increasing mixing time. This study was supported by Bioengineering for Human Health Grant from UNL and UNMC.

  3. Does it pay to have a damper in a powered ankle prosthesis? A power-energy perspective.

    Science.gov (United States)

    Eslamy, Mahdy; Grimmer, Martin; Rinderknecht, Stephan; Seyfarth, Andre

    2013-06-01

    In this paper we investigated on peak power (PP) and energy (ER) requirements for different active ankle actuation concepts that can have both elasticity and damping characteristics. A lower PP or ER requirement is an important issue because it will lead to a smaller motor or battery. In addition to spring, these actuation concepts are assumed to have (passive) damper in series (series elastic-damper actuator SEDA) or parallel (parallel elastic-damper actuator PEDA) to the motor. For SEA (series elastic actuator), SEDA and PEDA, we calculated the required minimum motor PP and ER in different human gaits: normal level walking, ascending and descending the stairs. We found that for level walking and ascending the stairs, the SEA concept, and for descending, the SEDA, were the favorable concepts to reduce required minimum PP and ER in comparison to a DD (direct drive) concept. In SEDA concept, the minimum PP could be reduced to half of what SEA would require. Nevertheless, it was found that spring was always required, however damper showed 'task specific' advantages. As a result, if a simple design perspective is in mind, from PP-ER viewpoint, SEA could be the best compromise to be used for different above-mentioned gaits. For SEDA or PEDA concepts, a controllable damper should be used. In addition, our results show that it is beneficial to select spring stiffness in SEA, based on level walking gait. The PP and ER requirements would increase very slightly for stairs ascending, and to some extent (10.5%) for descending as a consequence of this selection. In contrast, stiffness selection based on stair ascending or descending, increases the PP requirements of level walking more noticeably (17-24%).

  4. Level Classifications of Foundation Stiffness

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Liingaard, Morten

    2007-01-01

    This article describes a foundation module developed and implemented in both HAWC and FLEX capable of to simulate the frequency dependent stiffness and damping of foundations e.g. pile, gravitation and bucket foundations.......This article describes a foundation module developed and implemented in both HAWC and FLEX capable of to simulate the frequency dependent stiffness and damping of foundations e.g. pile, gravitation and bucket foundations....

  5. Revision of the aseptic and septic total ankle replacement.

    Science.gov (United States)

    Espinosa, Norman; Wirth, Stephan Hermann

    2013-04-01

    Total ankle replacement has become a popular treatment of symptomatic end-stage ankle osteoarthritis. Contemporary total ankle replacement systems provide more anatomic and biomechanically sound function. However, longevity is still limited and long-term results of modern total ankle replacement designs are not available. In the case of failure, conversion into arthrodesis has remained the treatment of choice but at the cost of hindfoot function and potential degeneration of the adjacent joints. Thus, revision total ankle replacement by exchange of the prosthetic components represents an attractive solution. This article focuses on revision total ankle replacement and conversion to ankle arthrodesis.

  6. FATIGUE DEVICE FOR TESTING ANKLE JOINT ENDOPROSTHESES

    Directory of Open Access Journals (Sweden)

    Cristian TOADER-PASTI

    2012-05-01

    Full Text Available The paper proposes a model of a fatigue device for testing dedicated to ankle prostheses. The concept of the testing device relies on two aspects: almost any type of ankle prosthesis can be tested on it and it has to work on INSTRON axial-torsion testing machine. Starting from these requirements, a 3D functional assembly that reproduces the real movement of the ankle joint during gait cycle has been designed. The device is based on a cam-follower mechanism.

  7. Foot and ankle injuries in theatrical dancers.

    Science.gov (United States)

    Hardaker, W T; Margello, S; Goldner, J L

    1985-10-01

    The theatrical dancer is a unique combination of athlete and artist. The physical demands of dance class, rehearsal, and performance can lead to injury, particularly to the foot and ankle. Ankle sprains are the most common acute injury. Chronic injuries predominate and relate primarily to the repeated impact loading of the foot and ankle on the dance floor. Contributing factors include anatomic variation, improper technique, and fatigue. Early and aggressive conservative management is usually successful and surgery is rarely indicated. Orthotics play a limited but potentially useful role in treatment. Following treatment, a structured rehabilitation program is fundamental to the successful return to dance.

  8. Conversion of ankle autofusion to total ankle replacement using the Salto XT revision prosthesis.

    Science.gov (United States)

    Williamson, Emilie R C; Demetracopoulos, Constantine A; Ellis, Scott J

    2016-09-01

    Few reports in the literature have described the conversion of a surgically fused ankle to a total ankle replacement. The takedown of an autofusion and conversion to a prosthesis has not been described. We report the case of a patient with severe rheumatoid arthritis with an ankle autofusion fixed in equinus and severe talonavicular arthritis that was converted to ankle replacement using the Salto XT revision system. We describe the reasons why the decision was made to perform total ankle arthroplasty while concomitantly fusing the talonavicular joint, and discuss the rationale of the various surgical treatment options considered. We describe the clinical and radiographic outcomes achieved in this case. At 12 months post-operatively the patient reported significant reduction of pain, increased FAOS scores and had increased ankle range of motion.

  9. Biomechanics of the ankle joint and clinical outcomes of total ankle replacement.

    Science.gov (United States)

    Michael, Junitha M; Golshani, Ashkahn; Gargac, Shawn; Goswami, Tarun

    2008-10-01

    Until the 1970s ankle arthrodesis was considered to be the "gold-standard" to treat arthritis. But the low fusion rate of ankle arthrodeses along with the inability to achieve normal range of motion led to the growing interest in the development of total ankle replacements. Though the short-term outcomes were good, their long-term outcomes were not as promising. To date, most models do not exactly mimic the anatomical functionality of a natural ankle joint. Therefore, research is being conducted worldwide to either enhance the existing models or develop new models while understanding the intricacies of the joint more precisely. This paper reviews the anatomical and biomechanical aspects of the ankle joint. Also, the evolution and comparison of clinical outcomes of various total ankle replacements are presented.

  10. Sprint interval and traditional endurance training induce similar improvements in peripheral arterial stiffness and flow-mediated dilation in healthy humans.

    Science.gov (United States)

    Rakobowchuk, Mark; Tanguay, Sophie; Burgomaster, Kirsten A; Howarth, Krista R; Gibala, Martin J; MacDonald, Maureen J

    2008-07-01

    Low-volume sprint interval training (SIT), or repeated sessions of brief, intense intermittent exercise, elicits metabolic adaptations that resemble traditional high-volume endurance training (ET). The effects of these different forms of exercise training on vascular structure and function remain largely unexplored. To test the hypothesis that SIT and ET would similarly improve peripheral artery distensibility and endothelial function and central artery distensibility, we recruited 20 healthy untrained subjects (age: 23.3 +/- 2.8 yr) and had them perform 6 wk of SIT or ET (n = 5 men and 5 women per group). The SIT group completed four to six 30-s "all-out" Wingate tests separated by 4.5 min of recovery 3 days/wk. The ET group completed 40-60 min of cycling at 65% of their peak oxygen uptake (Vo2peak) 5 days/wk. Popliteal endothelial function, both relative and normalized to shear stimulus, was improved after training in both groups (main effect for time, P < 0.05). Carotid artery distensibility was not statistically altered by training (P = 0.29) in either group; however, popliteal artery distensibility was improved in both groups to the same degree (main effect, P < 0.05). We conclude that SIT is a time-efficient strategy to elicit improvements in peripheral vascular structure and function that are comparable to ET. However, alterations in central artery distensibility may require a longer training stimuli and/or greater initial vascular stiffness than observed in this group of healthy subjects.

  11. Torque-stiffness-controlled dynamic walking with central pattern generators.

    Science.gov (United States)

    Huang, Yan; Vanderborght, Bram; Van Ham, Ronald; Wang, Qining

    2014-12-01

    Walking behavior is modulated by controlling joint torques in most existing passivity-based bipeds. Controlled Passive Walking with adaptable stiffness exhibits controllable natural motions and energy efficient gaits. In this paper, we propose torque-stiffness-controlled dynamic bipedal walking, which extends the concept of Controlled Passive Walking by introducing structured control parameters and a bio-inspired control method with central pattern generators. The proposed walking paradigm is beneficial in clarifying the respective effects of the external actuation and the internal natural dynamics. We present a seven-link biped model to validate the presented walking. Effects of joint torque and joint stiffness on gait selection, walking performance and walking pattern transitions are studied in simulations. The work in this paper develops a new solution of motion control of bipedal robots with adaptable stiffness and provides insights of efficient and sophisticated walking gaits of humans.

  12. Transfibular ankle arthrodesis: A novel method for ankle fusion - A short term retrospective study

    Directory of Open Access Journals (Sweden)

    S Muthukumar Balaji

    2017-01-01

    Full Text Available Background: Ankle arthrodesis has long been the traditional operative treatment for posttraumatic arthritis, rheumatoid arthritis, infection, neuromuscular conditions, and salvage of failed ankle arthroplasty. It remains the treatment of choice for patients in whom heavy and prolonged activity is anticipated. We present our short term followup study of functional outcome of patients who underwent transfibular ankle arthrodesis for arthritis of ankle due to various indications. Materials and Methods: 29 transfibular ankle arthrodesis in 29 patients performed between April 2009 and April 2014 were included in this study. The mean age was 50 years (range 22-75 years. The outcome analysis with a minimum of 1-year postoperative followup were included. All the patients were assessed with the American Orthopaedic Foot and Ankle Society (AOFAS Hindfoot scale. Results: All cases of ankle fusions (100% progressed to solid union in a mean postoperative duration of 3.8 months (range 3-6 months. All patients had sound arthrodesis. The mean followup period was 32.52 months (standard deviation ± 10.34. The mean AOFAS score was 74 (pain score = 32, functional score = 42. We found that twenty patients (68.96% out of 29, had excellent results, 7 (24.13% had good, and 2 (6.89% showed fair results. Conclusion: Transfibular ankle arthrodesis is a simple and effective procedure for ankle arthritis. It achieves a high rate of union and good functional outcome on midterm followup.

  13. Transfibular ankle arthrodesis: A novel method for ankle fusion – A short term retrospective study

    Science.gov (United States)

    Balaji, S Muthukumar; Selvaraj, V; Devadoss, Sathish; Devadoss, Annamalai

    2017-01-01

    Background: Ankle arthrodesis has long been the traditional operative treatment for posttraumatic arthritis, rheumatoid arthritis, infection, neuromuscular conditions, and salvage of failed ankle arthroplasty. It remains the treatment of choice for patients in whom heavy and prolonged activity is anticipated. We present our short term followup study of functional outcome of patients who underwent transfibular ankle arthrodesis for arthritis of ankle due to various indications. Materials and Methods: 29 transfibular ankle arthrodesis in 29 patients performed between April 2009 and April 2014 were included in this study. The mean age was 50 years (range 22-75 years). The outcome analysis with a minimum of 1-year postoperative followup were included. All the patients were assessed with the American Orthopaedic Foot and Ankle Society (AOFAS) Hindfoot scale. Results: All cases of ankle fusions (100%) progressed to solid union in a mean postoperative duration of 3.8 months (range 3–6 months). All patients had sound arthrodesis. The mean followup period was 32.52 months (standard deviation ± 10.34). The mean AOFAS score was 74 (pain score = 32, functional score = 42). We found that twenty patients (68.96%) out of 29, had excellent results, 7 (24.13%) had good, and 2 (6.89%) showed fair results. Conclusion: Transfibular ankle arthrodesis is a simple and effective procedure for ankle arthritis. It achieves a high rate of union and good functional outcome on midterm followup. PMID:28216754

  14. Primary ankle arthrodesis for neglected open weber B ankle fracture dislocation.

    LENUS (Irish Health Repository)

    Thomason, Katherine

    2014-07-01

    Primary ankle arthrodesis used to treat a neglected open ankle fracture dislocation is a unique decision. A 63-year-old man presented to the emergency department with a 5-day-old open fracture dislocation of his right ankle. After thorough soft tissue debridement, primary arthrodesis of the tibiotalar joint was performed using initial Kirschner wire fixation and an external fixator. Definitive soft tissue coverage was later achieved using a latissimus dorsi free flap. The fusion was consolidated to salvage the limb from amputation. The use of primary arthrodesis to treat a compound ankle fracture dislocation has not been previously described.

  15. Lichen simplex chronicus on the ankle (image)

    Science.gov (United States)

    Lichen simplex chronicus on the ankle: Lichen simplex chronicus is also known as neurodermatitis. A minor itch may encourage scratching which increases the irritation, leading to more scratching. This ...

  16. Compression therapy after ankle fracture surgery

    DEFF Research Database (Denmark)

    Winge, R; Bayer, L; Gottlieb, H

    2017-01-01

    PURPOSE: The main purpose of this systematic review was to investigate the effect of compression treatment on the perioperative course of ankle fractures and describe its effect on edema, pain, ankle joint mobility, wound healing complication, length of stay (LOS) and time to surgery (TTS). The aim...... undergoing surgery, testing either intermittent pneumatic compression, compression bandage and/or compression stocking and reporting its effect on edema, pain, ankle joint mobility, wound healing complication, LOS and TTS. To conclude on data a narrative synthesis was performed. RESULTS: The review included...... eight studies (451 patients). Seven studies found a significant effect on edema, two studies described a significant reduction in pain, one a positive effect on ankle movement, two a positive effect on wound healing, one a reduction in LOS and finally two studies reported reduction in TTS. A systematic...

  17. American College of Foot and Ankle Surgeons

    Science.gov (United States)

    ... Practice Management Education Opportunities Practice Management e-Learning e-Learning CME Transcripts Corporate Relations Faculty Application Research & Publications Journal of Foot and Ankle Surgery ACFAS Update Read ...

  18. A Stiffness Estimator for Agonistic-Antagonistic Variable-Stiffness-Actuator Devices

    OpenAIRE

    Menard, Tomas; Grioli, Giorgio; Bicchi, Antonio

    2014-01-01

    International audience; Safe Physical Human Robot Interaction, conservation of energy and adaptability are just the main robotic applications that prompted the development of a number of Variable Stiffness Actuators (VSA). Implemented in a variety of ways, they use various technologies, and feature the most diverse mechanical solutions, all of which share a fundamentally unavoidable nonlinear behavior. The control schemes proposed for these actuators typically aim at independent control of th...

  19. Feasibility and Reliability of Quantifying Passive Muscle Stiffness in Young Children Using Shear Wave Ultrasound Elastography

    Science.gov (United States)

    Brandenburg, Joline E.; Eby, Sarah F.; Song, Pengfei; Zhao, Heng; Landry, Bradford W.; Kingsley-Berg, Shirley; Bamlet, William R.; Chen, Shigao; Sieck, Gary C.; An, Kai-Nan

    2014-01-01

    Objective To investigate the feasibility and reliability of passive muscle stiffness measurements in children through use of shear wave ultrasound elastography. Methods This is a prospective cross -sectional study quantifying the passive stiffness of bilateral lateral gastrocnemii muscles during passive stretch in twenty typically developing children (age range, 2.0–12.6 years). Data collected included passive stiffness of the lateral gastrocnemius muscle (shear modulus in kilopascal [kPa]) at four positions of progressive passive foot dorsiflexion; demographic characteristics of the child participants; and comparison of demographic characteristics with the shear modulus. Results Passive stiffness increased with increasing stretch (mean [SD] range of stretch, 7.1 [2.0]–36.2 [22.0] kPa). For all four foot positions, no significant difference was found between right and left legs (range P=0.42 to P=0.98) or between the sexes (range P=0.28 to P> 0.99). No correlation of passive muscle stiffness to age, body mass index, or ankle range of motion was found. Reliability of measurements was good to excellent (mean [95% CI] range of reliability 0.67 [0.44–0.83] to 0.80 [0.63–0.90]). Conclusions Measurements of passive stiffness of the lateral gastrocnemius muscle are feasible and reliable in children as young as 2 years. Because the present study found no significant difference between sex and the side tested in this age-group, future studies involving children of this age range may not need to be stratified on the basis of these parameters. Defining normal passive muscle stiffness in children is critical for identifying and understanding the implications of abnormal passive muscle stiffness in children with neuromuscular disorders. PMID:25792582

  20. Postoperative infection in the foot and ankle.

    LENUS (Irish Health Repository)

    Chan, Victoria O

    2012-07-01

    Our discussion highlights the commonly performed surgical procedures in the foot and ankle and reviews the various imaging modalities available for the detection of infection with graphic examples to better enable radiologists to approach the radiological evaluation of postoperative infection in the foot and ankle. Discrimination between infectious and noninfectious inflammation remains a diagnostic challenge usually needing a combination of clinical assessment, laboratory investigations, and imaging studies to increase diagnostic accuracy.

  1. Salvage arthrodesis for failed total ankle arthroplasty

    Science.gov (United States)

    Zürcher, Arthur W

    2010-01-01

    Background and purpose Total ankle arthroplasty (TAA) has gained popularity in recent years. If it fails, however, salvage arthrodesis must be reliable as a rescue procedure. We therefore investigated the clinical, radiographic, and subjective outcome after salvage arthrodesis in a consecutive group of patients, and concentrated on the influence of the method of fixation on union rate and on salvage in inflammatory joint disease. Patients and methods Between 1994 and 2005, salvage arthrodesis was performed on 18 ankles (18 patients). Diagnosis was inflammatory joint disease (IJD) in 15 cases and osteoarthritis (OA) in 3. Tibio-talar fusion was performed in 7 ankles, and tibio-talocalcaneal fusion in 11. Serial radiographs were studied for time to union. Clinical outcome at latest follow-up was measured by the AOFAS score, the foot function index (FFI) and by VAS scores for pain, function, and satisfaction. Results Blade plates were used in 7 ankles (4 IJD, 3 OA); all united. Nonunion developed in 7 of the 11 rheumatic ankles stabilized by other methods. 11 patients (8 fused ankles, 3 nonunions) were available for clinical evaluation. Their mean AOFAS score was 62 and mean overall FFI was 70. VAS score for pain was 20, for function 64, and for satisfaction 74. The scores were similar in united and non-united ankles. Interpretation Blade plate fixation is successful in salvage arthrodesis for failed TAA. A high nonunion rate was found after salvage ankle arthrodesis in IJD with other methods of fixation. Clinical results were fair to good. PMID:20175648

  2. Total Ankle Arthroplasty: A Brief Review

    OpenAIRE

    Mann, Roger A.; Harrison, Matthew J.

    2012-01-01

    Ankle fusion has long been the standard of treatment for end-stage ankle arthritis, and a successful arthroplasty has been a long sought alternative. It is a motion sparing procedure and may greatly reduce the potential for adjacent level degeneration as seen with arthrodesis. The typical candidate for arthroplasty is a healthy low demand patient, although the indications are widening as the success of the procedure has increased. Nevertheless, it is not fail-safe, technical expertise and exp...

  3. An epidemiological survey on ankle sprain.

    OpenAIRE

    Yeung, M S; Chan, K. M.; So, C H; Yuan, W Y

    1994-01-01

    Ankle sprain is a common sports injury and is often regarded as trivial by athletes and coaches. This epidemiological study was conducted among three categories of Hong Kong Chinese athletes: national teams, competitive athletes and recreational athletes. This study shows that as much as 73% of all athletes had recurrent ankle sprain and 59% of these athletes had significant disability and residual symptoms which led to impairment of their athletic performance. This study indicates that a pro...

  4. TOTAL ANKLE REPLACEMENT: WHY, WHEN AND HOW?

    Science.gov (United States)

    Bonasia, Davide Edoardo; Dettoni, Federico; Femino, John E; Phisitkul, Phinit; Germano, Margherita; Amendola, Annunziato

    2010-01-01

    Total ankle replacement (TAR) was first attempted in the 1970s, but poor results led to its being considered inferior to ankle fusion until the late 1980s and early 1990s. By that time, newer designs which more closely replicated the natural anatomy of the ankle, showed improved clinical outcomes.1 Currently, even though controversy still exists about the effectiveness of TAR compared to ankle fusion, TAR has shown promising mid-term results and should no longer be considered an experimental procedure. Factors related to improved TAR outcomes include: 1) better patient selection, 2) more precise knowledge and replication of ankle biomechanics, 3) the introduction of less-constrained designs with reduced bone resection and no need for cementation, and 4) greater awareness of soft-tissue balance and component alignment. When TAR is performed, a thorough knowledge of ankle anatomy, pathologic anatomy and biomechanics is needed along with a careful pre-operative plan. These are fundamental in obtaining durable and predictable outcomes. The aim of this paper is to outline these aspects through a literature review. PMID:21045984

  5. Total ankle replacement for posttraumatic arthritis

    Science.gov (United States)

    Weme, Rebecca A Nieuwe; van Solinge, Guido; N Doornberg, Job; Sierevelt, Inger; Haverkamp, Daniël; Doets, H Cornelis

    2015-01-01

    Background and purpose Most studies on total ankle replacement (TAR) have used a case mix of patients. We evaluated the outcome of TAR performed for end-stage arthritis either because of fracture or ligamentous injury. Patients and methods We prospectively followed 88 consecutive patients (50 postfracture ankles and 40 ankles with instability arthritis (2 bilateral)) who underwent TAR between 2001 and 2009. Mean follow-up for both groups was 5 years. Results Preoperative varus deformity of 10° or more was present in 23 ankles in the instability group. At 6 years, survival with revision or salvage fusion as an endpoint was 87% (95% CI: 74–99) in the postfracture group and 79% (95% CI: 63–94) in the instability group. Progressive periprosthetic osteolysis was seen in 23 ankles, and required salvage fusion in 6. The number of reoperations was similar in both groups. Clinical outcome, as assessed with 2 ankle scores and 2 questionnaires, showed good results and was similar at the latest follow-up. Interpretation The outcome was similar in the postfracture and instability groups and also similar to that reported in series including a case mix of patients. In contrast to earlier reports, preoperative frontal plane deformity in this series was not identified as a risk factor for failure. PMID:25772269

  6. Hemoglobin A1c and arterial and ventricular stiffness in older adults.

    Directory of Open Access Journals (Sweden)

    Susan J Zieman

    Full Text Available OBJECTIVE: Arterial and ventricular stiffening are characteristics of diabetes and aging which confer significant morbidity and mortality; advanced glycation endproducts (AGE are implicated in this stiffening pathophysiology. We examined the association between HbA(1c, an AGE, with arterial and ventricular stiffness measures in older individuals without diabetes. RESEARCH DESIGN & METHODS: Baseline HbA(1c was measured in 830 participants free of diabetes defined by fasting glucose or medication use in the Cardiovascular Health Study, a population-based cohort study of adults aged ≥ 65 years. We performed cross-sectional analyses using baseline exam data including echocardiography, ankle and brachial blood pressure measurement, and carotid ultrasonography. We examined the adjusted associations between HbA(1c and multiple arterial and ventricular stiffness measures by linear regression models and compared these results to the association of fasting glucose (FG with like measures. RESULTS: HbA(1c was correlated with fasting and 2-hour postload glucose levels (r = 0.21; p<0.001 for both and positively associated with greater body-mass index and black race. In adjusted models, HbA(1c was not associated with any measure of arterial or ventricular stiffness, including pulse pressure (PP, carotid intima-media thickness, ankle-brachial index, end-arterial elastance, or left ventricular mass (LVM. FG levels were positively associated with systolic, diastolic and PP and LVM. CONCLUSIONS: In this sample of older adults without diabetes, HbA(1c was not associated with arterial or ventricular stiffness measures, whereas FG levels were. The role of AGE in arterial and ventricular stiffness in older adults may be better assessed using alternate AGE markers.

  7. Arterial Stiffness: Recommendations and Standardization

    Science.gov (United States)

    Townsend, Raymond R.

    2017-01-01

    The use of arterial stiffness measurements in longitudinal cohorts of normal populations, hypertensive patients, diabetic patients, healthy elderly, and patients on hemodialysis have confirmed the value of this important measure of arterial health, and established its complementary role to measures of blood pressure. Its contribution to understanding cardiovascular and mortality risk beyond blood pressure measurements has moved measures of arterial stiffness into the ranks of factors such as elevated cholesterol, diabetes, and left ventricular hypertrophy in considering cardiovascular risk. The recent international collaboration's publication of reference ranges for normal people and those with hypertension, along with the American Heart Association's recent scientific statement on standardizing arterial stiffness measurements are important aspects to consider in future studies employing these valuable methods, particularly as interventions that not only lower blood pressure but improve arterial function are tested in the clinical arena. PMID:28275588

  8. A multiwell platform for studying stiffness-dependent cell biology.

    Directory of Open Access Journals (Sweden)

    Justin D Mih

    Full Text Available Adherent cells are typically cultured on rigid substrates that are orders of magnitude stiffer than their tissue of origin. Here, we describe a method to rapidly fabricate 96 and 384 well platforms for routine screening of cells in tissue-relevant stiffness contexts. Briefly, polyacrylamide (PA hydrogels are cast in glass-bottom plates, functionalized with collagen, and sterilized for cell culture. The Young's modulus of each substrate can be specified from 0.3 to 55 kPa, with collagen surface density held constant over the stiffness range. Using automated fluorescence microscopy, we captured the morphological variations of 7 cell types cultured across a physiological range of stiffness within a 384 well plate. We performed assays of cell number, proliferation, and apoptosis in 96 wells and resolved distinct profiles of cell growth as a function of stiffness among primary and immortalized cell lines. We found that the stiffness-dependent growth of normal human lung fibroblasts is largely invariant with collagen density, and that differences in their accumulation are amplified by increasing serum concentration. Further, we performed a screen of 18 bioactive small molecules and identified compounds with enhanced or reduced effects on soft versus rigid substrates, including blebbistatin, which abolished the suppression of lung fibroblast growth at 1 kPa. The ability to deploy PA gels in multiwell plates for high throughput analysis of cells in tissue-relevant environments opens new opportunities for the discovery of cellular responses that operate in specific stiffness regimes.

  9. Stiffness mapping prostate biopsy samples using a tactile sensor.

    Science.gov (United States)

    Peng, Qiyu; Omata, Sadao; Peehl, Donna M; Constantinou, Chris E

    2011-01-01

    Previous studies have demonstrated that the stiffness of cancerous cells reflects their pathological stage and progression rates, with increased cancerous cell stiffness associated with increased aggressiveness. Therefore, the elasticity of the cancerous cells has the potential to be used as an indicator of the cancer's aggressiveness. However, the sensitivity and resolution of current palpation and imaging techniques are not sufficient to detect small cancerous tissues. In previous studies, we developed a tactile-based device to map with high resolution the stiffness of a tissue section. The purpose of this study is to evaluate this device using different tissues (BPH, Cancer and PZ) collected from human prostates. The preliminary results show that the tactile device is sensitive enough to tell the differences of the stiffness of different tissues. The results also disclosed the factors (humidity, temperature and tissue degradation) which could dramatically affect the results of stiffness mapping. The tactile technology described in this paper has the potential to help disclose the underlying mechanical mechanisms that lead to increased stiffness in prostate tumors.

  10. Control of a powered ankle-foot prosthesis based on a neuromuscular model.

    Science.gov (United States)

    Eilenberg, Michael F; Geyer, Hartmut; Herr, Hugh

    2010-04-01

    Control schemes for powered ankle-foot prostheses rely upon fixed torque-ankle state relationships obtained from measurements of intact humans walking at target speeds and across known terrains. Although effective at their intended gait speed and terrain, these controllers do not allow for adaptation to environmental disturbances such as speed transients and terrain variation. Here we present an adaptive muscle-reflex controller, based on simulation studies, that utilizes an ankle plantar flexor comprising a Hill-type muscle with a positive force feedback reflex. The model's parameters were fitted to match the human ankle's torque-angle profile as obtained from level-ground walking measurements of a weight and height-matched intact subject walking at 1 m/s. Using this single parameter set, clinical trials were conducted with a transtibial amputee walking on level ground, ramp ascent, and ramp descent conditions. During these trials, an adaptation of prosthetic ankle work was observed in response to ground slope variation, in a manner comparable to intact subjects, without the difficulties of explicit terrain sensing. Specifically, the energy provided by the prosthesis was directly correlated to the ground slope angle. This study highlights the importance of neuromuscular controllers for enhancing the adaptiveness of powered prosthetic devices across varied terrain surfaces.

  11. [Revision arthroplasty of the ankle joint].

    Science.gov (United States)

    Hintermann, B; Barg, A; Knupp, M

    2011-11-01

    In the last 20 years total ankle replacement has become a viable alternative to arthrodesis for end-stage osteoarthritis of the ankle. Numerous ankle prosthesis designs have appeared on the market in the past and attracted by the encouraging intermediate results reported in the literature, many surgeons have started to perform this procedure. With increased availability on the market the indications for total ankle replacement have also increased in recent years. In particular, total ankle replacement may now be considered even in younger patients. Therefore, despite progress in total ankle arthroplasty the number of failures may increase. Up to now, arthrodesis was considered to be the gold standard for salvage of failed ankle prostheses. Because of extensive bone loss on the talar side, in most instances tibiocalcaneal fusion is the only reliable solution. An alternative to such extended hindfoot fusions would be revision arthroplasty. To date, however, there are no reported results of revision arthroplasty for salvage of a failed ankle replacement.Based on our experience prosthetic components with a flat undersurface are most likely to be able to find solid support on remaining bone stock. The first 83 cases (79 patients, 46 males, 33 females, average age 58.9 years, range 30.6-80.7 years) with a average follow-up of 5.4 years (range 2-11 years) showed excellent to good results in 69 cases (83%), a satisfactory result in 12 cases (15%) and a fair result in 2 cases (2%) and 47 patients (56%) were pain free. Primary loosening was noted in three cases and of these two cases were successfully revised by another total ankle replacement and in one case with arthrodesis. Another case with hematogenous infection was also revised by arthrodesis. At the last follow-up control two components were considered to be loose and the overall loosening rate was thus 6%.This series has proven that revision arthroplasty can be a promising option for patients with failed total

  12. Arterial Stiffness and Pharmacological Interventions – The TRanscend Arterial stiffNess Substudy (TRANS study

    Directory of Open Access Journals (Sweden)

    Jirar Topouchian

    2007-09-01

    Full Text Available Jirar Topouchian1, Ramzi El Feghali1, Bruno Pannier1, Shuyu Wang2, Feng Zhao3, Karel Smetana4, Koon Teo3, Roland Asmar11The CardioVascular Institute, Paris, France; 2Beijing Clinical Trial and Research Center, Beijing, China; 3Population Health Research Institute, Hamilton, Canada; 4Vojenska nemocnice Plzen, Pizen, Czech RepublicAbstract: The degree of arterial stiffness is correlated with the risk of cardiovascular diseases and it is a powerful predictor for morbidity and mortality. Studies have shown that arterial stiffness reduction is associated with an improvement in survival. Reduction of arterial stiffness by pharmacological drugs varies according to the drugs and doses used and duration of treatment. This effect on the arteries differs among the various classes of drugs and among individual drugs in the same class. Quantification of the stiffness and other properties of the arterial wall can be used to monitor the responses to therapy in individuals with hypertension and other cardiovascular diseases. These measures can then be used as surrogate markers for the risk of clinical events. Inhibition of the renin-angiotensin system (RAS is associated with an important decrease in cardiovascular risk. Findings from clinical trials support the hypothesis that the protective effects of RAS inhibition are partly independent from blood pressure reduction and related to several mechanisms including vascular protective effects. The aim of the TRanscend Arterial stiffNess Substudy (TRANS is to assess the effect of an angiotensin II receptor blocker (ARB, telmisartan, on the arterial stiffness in a subgroup of patients from the Telmisartan Randomized Assessment Study in aCE iNtolerant subjects with cardiovascular Disease (TRANSCEND trial. The TRANSCEND trial is an international, multicenter, randomized double blind placebo controlled trial of telmisartan that enrolled patients at high risk for cardiovascular events. Some clinical baseline data of the

  13. Ambulatory arterial stiffness indices and target organ damage in hypertension

    Directory of Open Access Journals (Sweden)

    Gómez-Marcos Manuel

    2012-01-01

    Full Text Available Abstract Background The present study was designed to evaluate which arterial stiffness parameter - AASI or the home arterial stiffness index (HASI - correlates best with vascular, cardiac and renal damage in hypertensive individuals. Methods A cross-sectional study was carried out involving 258 hypertensive patients. AASI and HASI were defined as the 1-regression slope of diastolic over systolic blood pressure readings obtained from 24-hour recordings and home blood pressure over 6 days. Renal damage was evaluated by glomerular filtration rate (GFR and microalbuminuria; vascular damage by carotid intima-media thickness (IMT, pulse wave velocity (PWV and ankle/brachial index (ABI; and left ventricular hypertrophy by the Cornell voltage-duration product (VDP and the Novacode index. Results AASI and HASI were not correlated with microalbuminuria, however AASI and HASI- blood pressure variability ratio (BPVR showed negative correlation with GRF. The Cornell PDV was positively correlated with AASI- BPVR-Sleep (r = 0.15, p Conclusions After adjusting for age, gender and 24-hour heart, the variables that best associated with the variability of IMT, PWV and ABI were AASI and Awake-AASI, and with GFR was HASI-BPVR.

  14. One year follow-up after operative ankle fractures: a prospective gait analysis study with a multi-segment foot model.

    Science.gov (United States)

    Wang, Ruoli; Thur, Charlotte K; Gutierrez-Farewik, Elena M; Wretenberg, Per; Broström, Eva

    2010-02-01

    Ankle fractures are one of the most common lower limb traumas. Several studies reported short- and long-term post-operative results, mainly determined by radiographic and subjective functional evaluations. Three-dimensional gait analysis with a multi-segment foot model was used in the current study to quantify the inter-segment foot motions in 18 patients 1 year after surgically treated ankle fractures. Data were compared to that from gender- and age-matched healthy controls. The correlations between Olerud/Molander ankle score and kinematics were also evaluated. Patients with ankle fractures showed less plantarflexion and smaller range of motion in the injured talocrural joint, which were believed to be a sign of residual joint stiffness after surgery and immobilization. Moreover, the forefoot segment had smaller sagittal and transverse ranges of motion, less plantarflexion and the hallux segment had less dorsiflexion and smaller sagittal range of motion. The deviations found in the forefoot segment may contribute to the compensation mechanisms of the injured ankle joint. Findings of our study show that gait analysis with a multi-segment foot model provides a quantitative and objective way to perform the dynamic assessment of post-operative ankle fractures, and makes it possible to better understand not only how the injured joint is affected, but also the surrounding joints.

  15. Lase Ultrasonic Web Stiffness tester

    Energy Technology Data Exchange (ETDEWEB)

    Tim Patterson, Ph.D., IPST at Ga Tech

    2009-01-12

    The objective is to provide a sensor that uses non-contact, laser ultrasonics to measure the stiffness of paper during the manufacturing process. This will allow the manufacturer to adjust the production process in real time, increase filler content, modify fiber refining and as result produce a quality product using less energy. The sensor operates by moving back and forth across the paper web, at pre-selected locations firing a laser at the sheet, measuring the out-of-plane velocity of the sheet then using that measurement to calculate sheet stiffness.

  16. Dynamic stiffness of suction caissons

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo; Liingaard, Morten; Andersen, Lars

    This report concerns the dynamic soil-structure interaction of steel suction caissons applied as foundations for offshore wind turbines. An emphasis is put on torsional vibrations and coupled sliding/rocking motion, and the influence of the foundation geometry and the properties of the surrounding...... soil is examined. The soil is simplified as a homogenous linear viscoelastic material and the dynamic stiffness of the suction caisson is expressed in terms of dimensionless frequency-dependent coefficients corresponding to the different degrees of freedom. The dynamic stiffness coefficients...

  17. Do Ankle Orthoses Improve Ankle Proprioceptive Thresholds or Unipedal Balance in Older Persons with Peripheral Neuropathy?

    Science.gov (United States)

    Son, Jaebum; Ashton-Miller, James A.; Richardson, James K.

    2010-01-01

    Objective To determine whether ankle orthoses that provide medial and lateral support, and have been found to decrease gait variability in older persons with peripheral neuropathy, decrease (improve) frontal plane ankle proprioceptive thresholds or increase unipedal stance time in that same population. Design Observational study in which unipedal stance time was determined with a stopwatch, and frontal plane ankle (inversion and eversion) proprioceptive thresholds were quantified during bipedal stance with and without the ankle orthoses, in 11 older diabetic subjects with peripheral neuropathy (8 men; age 72 ± 7.1 years) using a foot cradle system which presented a series of 100 rotational stimuli. Results The subjects demonstrated no change in combined frontal plane (inversion + eversion) proprioceptive thresholds or unipedal stance time with versus without the orthoses (1.06 ± 0.56 versus 1.13 ± 0.39 degrees, respectively; p = 0.955 and 6.1 ± 6.5 versus 6.2 ± 5.4 seconds, respectively; p = 0.922). Conclusion Ankle orthoses which provide medial-lateral support do not appear to change ankle inversion/eversion proprioceptive thresholds or unipedal stance time in older persons with diabetic peripheral neuropathy. Previously identified improvements in gait variability using orthoses in this population are therefore likely related to an orthotically-induced stiffening of the ankle rather than a change in ankle afferent function. PMID:20407302

  18. Measurement of blood pressure, ankle blood pressure and calculation of ankle brachial index in general practice

    DEFF Research Database (Denmark)

    Nexøe, Jørgen; Damsbo, Bent; Lund, Jens Otto

    2012-01-01

    BACKGROUND: Low ankle brachial index (ABI) is a sensitive measure of 'burden' of atherosclerosis, indicating cardiovascular risk of the asymptomatic patient. Conventionally, ABI values......BACKGROUND: Low ankle brachial index (ABI) is a sensitive measure of 'burden' of atherosclerosis, indicating cardiovascular risk of the asymptomatic patient. Conventionally, ABI values...

  19. Association between arterial stiffness, cerebral small vessel disease and cognitive impairment: a systematic review and meta-analysis

    Science.gov (United States)

    van Sloten, Thomas T; Protogerou, Athanase D; Henry, Ronald MA; Schram, Miranda T; Launer, Lenore J; Stehouwer, Coen DA

    2017-01-01

    Arterial stiffness may be a cause of cerebral small vessel disease and cognitive impairment. We therefore performed a systematic review and meta-analysis of studies on the association between stiffness, cerebral small vessel disease and cognitive impairment. For the associations between stiffness (i.e. carotid-femoral pulse wave velocity (cfPWV), brachial-ankle PWV (baPWV), carotid stiffness and pulse pressure) on the one hand and cerebral small vessel disease and cognitive impairment on the other, we identified 23 (n=15,666/22 cross-sectional/3 longitudinal) and 41 studies (n=57,671/30 cross-sectional/15 longitudinal), respectively. Pooled analyses of cross-sectional studies showed that greater stiffness was associated with markers of cerebral small vessel disease with odds ratios, per +1 SD, of 1.29 to 1.32 (P<.001). Studies on cognitive impairment could not be pooled due to large heterogeneity. Some (but not all) studies showed an association between greater stiffness and cognitive impairment, and the strength of this association was relatively weak. The present study supports the hypothesis that greater arterial stiffness is a contributor to microvascular brain disease. PMID:25827412

  20. Metabolic syndrome is associated with change in subclinical arterial stiffness - A community-based Taichung Community Health Study

    Directory of Open Access Journals (Sweden)

    Lin Wen-Yuan

    2011-10-01

    Full Text Available Abstract Background The aim of this study was to evaluate the effect of MetS on arterial stiffness in a longitudinal study. Methods Brachial-ankle pulse wave velocity (baPWV, a measurement interpreted as arterial stiffness, was measured in 1518 community-dwelling persons at baseline and re-examined within a mean follow-up period of 3 years. Multivariate linear regression with generalized estimating equations (GEE were used to examine the longitudinal relationship between MetS and its individual components and baPWV, while multivariate logistic regression with GEE was used to examine the longitudinal relationship between MetS and its individual components and the high risk group with arterial stiffness. Results Subjects with MetS showed significantly greater baPWV at the end point than those without MetS, after adjusting for age, gender, education, hypertension medication and mean arterial pressure (MAP. MetS was associated with the top quartile of baPWV (the high-risk group of arterial stiffness, adjusted odds ratio [95% confidence interval] 1.52 [1.21-1.90], and a significant linear trend of risk for the number of components of MetS was found (p for trend Conclusions MetS affects the subject's progression to arterial stiffness. Arterial stiffness increased as the number of MetS components increased. Management of MetS is important for preventing the progression to advanced arterial stiffness.

  1. Prostate cancer detection using a combination of Raman spectroscopy and stiffness sensing

    OpenAIRE

    Lindahl, Olof; Nyberg, Morgan; Jalkanen, Ville; Ramser, Kerstin

    2014-01-01

    Prostate cancer (PCa) is the most common cancer form for men in Europe. A sensor system combining Raman spectroscopy and stiffness sensing with a resonance sensor has recently been developed by us for prostate cancer detection. In this study the sensor system has been used for measurements on two slices of fresh human prostate tissue. The stiffness sensor could detect locations slices with significantly different stiffness contrasts (p < 0.05). Raman spectroscopic measurements could be per...

  2. The results of ankle arthrodesis with screws for end stage ankle arthrosis.

    Science.gov (United States)

    Torudom, Yingyong

    2010-02-01

    Aim of this study was to evaluate the results of ankle arthrodesis with screws in patients with ankle arthrosis. The author studied 19 patients (20 feet) who had been treated by ankle arthrodesis with screws from 2003 to 2008. Ten patients were men (11 feet) and nine (9 feet) were women. Their mean age was 56 years (30 to 65), and the average duration of follow-up was four years (2 to 6). Two compression screws were used in all feet. Union was achieved in 19 of the 20 feet (95%). Average scores for pain and clinical condition are increase after operation. One re-operation was performed for nonunion. Author conclude that ankle arthrodesis with screws was effective treatment for ankle arthrosis.

  3. Arthroscopic Management of Complications Following Total Ankle Replacement.

    Science.gov (United States)

    Lui, Tun Hing; Roukis, Thomas S

    2015-10-01

    There is great potential of managing the complications of total ankle replacement arthroscopically and endoscopically, and these procedures can be summarized into 3 groups. Group 1 includes procedures of the ankle joint proper with close proximity to the articular components of the total ankle replacement. Group 2 includes procedures of the tibia and talus with close proximity to the nonarticular parts of the total ankle replacement. Group 3 includes procedures that are away from the total ankle replacement. However, these remain master arthroscopist procedures and should be performed by foot and ankle surgeons who perform them with regularity.

  4. [Ankle joint arthritis--etiology, diagnosis and treatment].

    Science.gov (United States)

    Uri, Ofir; Haim, Amir

    2008-11-01

    Ankle joint arthritis causes functional limitation and affects the quality of life many patients. It follows traumatic injuries, inflammatory joint arthritis, primary osteoarthritis, hemochromatosis and infections. Understanding the unique anatomy and biomechanics of the ankle is important for diagnosis and treatment of ankle joint pathology. The treatment of ankle joint arthritis has advanced considerably in recent years and it is still a surgical challenge. Total ankle replacement seems to be a promising form of treatment, even though current data does not demonstrate advantages over ankle joint arthrodesis.

  5. Prospective study of ankle and foot fractures in elderly women

    Directory of Open Access Journals (Sweden)

    Yadagiri Surender Rao

    2015-01-01

    Full Text Available The epidemiology of ankle fractures in old people is changing as time passes on. The incidence of ankle fractures increases with advancing age. The study conducted was among a rural popula-tion which comprised of 68 women (32 women with ankle fractures & 36 women with foot fractures. Patients studied were in the age group more than 50 years. The study highlights the etiological & risk factors for fractures of ankle & foot. The commonest ankle fracture was the lateral malleolar fracture & the commonest foot fracture was the 5th Metatarsal fracture. Diabetes is a risk factor which increases the occurrence of ankle and foot injuries.

  6. [A very slow growing ankle swelling in a healthy male].

    Science.gov (United States)

    Merlo, Christoph; Merlo, Pierina; Holzinger, Fernando; Pranghofer, Sigrid; Pfeiffer, David; Nüesch, Reto

    2014-08-20

    We describe the case report of a 66-year-old man with a very slow growing ankle tumour caused by a subcutaneous fungal abscess. Phaeoacremonium inflatipes, a member of the Dematiaceae family, was identified by needle puncture and culture of the non-odorous creamy yellow brown fluid. The fungal pseudocyst was surgically removed in toto and no further fungicidal drug therapy was required. Human infections by dematiaceous fungi causes subcutaneous phaeohyphomycosis, a rare, deep fungal infection of the skin and subcutaneous tissues usually acquired through traumatic skin lesions. In addition, systemic infections are reported, predominantly in immunosuppressed individuals.

  7. Ankle fusion stability: a biomechanical comparison of external versus internal fixation.

    Science.gov (United States)

    Hoover, Justin R; Santrock, Robert D; James, William C

    2011-04-11

    This biomechanical study compares bimalleolar external fixation to conventional crossed-screw construct in terms of stability and compression for ankle arthrodesis. The goals of the study were to determine which construct is more stable with bending and torsional forces, and to determine which construct achieves more compression.Fourth-generation bone composite tibia and talocalcaneal models were made to 50th percentile anatomic specifications. Fourteen ankle fusion constructs were created with bimalleolar external fixators and 14 with crossed-screw constructs. Ultimate bend, torque, and compression testing were completed on the external fixator and crossed-screw constructs using a multidirectional Materials Testing Machine (MTS Systems Corp, Eden Prairie, Minnesota). Ultimate bend testing revealed a statistically significant difference (P=.0022) with the mean peak load to failure for the external fixator constructs of 973.2 N compared to 612.5 N for the crossed-screw constructs. Ultimate torque testing revealed the mean peak torque to failure for the external fixator construct was 80.2 Nm and 28.1 Nm for the crossed-screw construct, also a statistically significant difference (P=.0001). The compression testing yielded no statistically significant difference (P=.9268) between the average failure force of the external fixator construct (81.6 kg) and the crossed-screw construct (81.2 kg).With increased stiffness in both bending and torsion and comparable compressive strengths, bimalleolar external fixation is an excellent option for tibiotalar ankle arthrodesis.

  8. Three-dimensional finite element stress analysis of the polypropylene, ankle-foot orthosis: static analysis.

    Science.gov (United States)

    Chu, T M; Reddy, N P; Padovan, J

    1995-07-01

    An asymmetric 3-dimensional finite element model (FEM) of the ankle-foot orthosis (AFO) together with the ankle-foot complex was developed using the computer aided design (CAD) program PATRAN. Static analysis of normal and pathological motions of the ankle-foot complex such as the "drop-foot" problem were conducted using the FEM program ADINA. A total of 313 three dimensional solid elements and 10 truss elements were used. Heel strike and toe-off condition were simulated. Results revealed that the peak compressive stress (1.6 MPa) in the AFO model occurred in the heel regions of the AFO and the maximum tensile stress (0.8 MPa) occurred in the neck region of the AFO during toe-off. Parametric analyses revealed that the model was sensitive to the elastic moduli of the AFO and of the soft tissue, but was relatively insensitive to the ligament stiffness. The results confirmed the hypothesis that peak stresses in the orthosis occur in the heal and neck regions of the orthosis.

  9. Learning to walk with an adaptive gain proportional myoelectric controller for a robotic ankle exoskeleton.

    Science.gov (United States)

    Koller, Jeffrey R; Jacobs, Daniel A; Ferris, Daniel P; Remy, C David

    2015-11-04

    Robotic ankle exoskeletons can provide assistance to users and reduce metabolic power during walking. Our research group has investigated the use of proportional myoelectric control for controlling robotic ankle exoskeletons. Previously, these controllers have relied on a constant gain to map user's muscle activity to actuation control signals. A constant gain may act as a constraint on the user, so we designed a controller that dynamically adapts the gain to the user's myoelectric amplitude. We hypothesized that an adaptive gain proportional myoelectric controller would reduce metabolic energy expenditure compared to walking with the ankle exoskeleton unpowered because users could choose their preferred control gain. We tested eight healthy subjects walking with the adaptive gain proportional myoelectric controller with bilateral ankle exoskeletons. The adaptive gain was updated each stride such that on average the user's peak muscle activity was mapped to maximal power output of the exoskeleton. All subjects participated in three identical training sessions where they walked on a treadmill for 50 minutes (30 minutes of which the exoskeleton was powered) at 1.2 ms(-1). We calculated and analyzed metabolic energy consumption, muscle recruitment, inverse kinematics, inverse dynamics, and exoskeleton mechanics. Using our controller, subjects achieved a metabolic reduction similar to that seen in previous work in about a third of the training time. The resulting controller gain was lower than that seen in previous work (β=1.50±0.14 versus a constant β=2). The adapted gain allowed users more total ankle joint power than that of unassisted walking, increasing ankle power in exchange for a decrease in hip power. Our findings indicate that humans prefer to walk with greater ankle mechanical power output than their unassisted gait when provided with an ankle exoskeleton using an adaptive controller. This suggests that robotic assistance from an exoskeleton can allow

  10. Robot-Assisted Rehabilitation of Ankle Plantar Flexors Spasticity: A Three-Month Study with Proprioceptive Neuromuscular Facilitation

    Directory of Open Access Journals (Sweden)

    Zhihao Zhou

    2016-11-01

    Full Text Available In this paper, we aim to investigate the effect of Proprioceptive Neuromuscular Facilitation (PNF based rehabilitation for ankle plantar flexors spasticity by using a Robotic Ankle-foot Rehabilitation System (RARS. A modified robot-assisted system was proposed and seven post-stroke patients with hemiplegic spastic ankles participated a three-month of robotic PNF training. Their impaired sides were used as the experimental group while their unimpaired sides as the control group. A robotic intervention for the experimental group generally started from a two minutes passive stretching to warm-up or relax the soleus and gastrocnemius muscle and also ended with the same one. Then a PNF training session included 30 trails was activated between them. The rehabilitation trainings were carried out three times a week as an addition of their regular rehabilitation exercise. Passive ankle joint range of motion, resistance torque and stiffness were measured in both ankles before and after the intervention. The changes in Achilles' tendon length, walking speed, and lower limb function were also evaluated by the same physician or physiotherapist for each participant. Biomechanical measurements before interventions showed significant difference between the experimental group and the control group due to ankle spasticity. For the control group, there was no significant difference in the three months with no robotic intervention. But for the experimental group, passive dorsiflexion range of motion increased ( p0.05 . The robotic rehabilitation also improved the muscle strength ( p0.05 and fast walking speed ( p<0.05 . These results indicated that PNF based robotic intervention could significantly alleviate lower limb spasticity and improve the motor function in chronic stroke participant. The robotic system could potentially be used as an effective tool in post-stroke rehabilitation training.

  11. Complications after ankle and hindfoot arthroscopy.

    Science.gov (United States)

    Blázquez Martín, T; Iglesias Durán, E; San Miguel Campos, M

    To evaluate the percentage of complications associated with ankle and hindfoot arthroscopy in our hospital and to compare the results with those reported in the literature. A retrospective descriptive review was conducted on the complications associated with ankle and hindfoot arthroscopy performed between May 2008 and April 2013. A total of 257 arthroscopy were performed, 23% on subtalar joint, and 77% of ankle joint. An anterior approach was used in 69%, with 26% by a posterior approach, and the remaining 5% by combined access. A total of 31 complications (12.06%) were found. The most common complication was neurological damage (14 cases), with the most affected nerve being the superficial peroneal nerve (8 cases). Persistent drainage through the portals was found in 10 cases, with 4 cases of infection, and 3 cases of complex regional pain syndrome type 1. There have been substantial advances in arthroscopy of ankle and hindfoot in recent years, expanding its indications, and also the potential risk of complications. The complication rate (12.06%) found in this study is consistent with that described in the literature (0-17%), with neurological injury being the most common complication. Ankle and hindfoot arthroscopy is a safe procedure. It is important to make a careful preoperative planning, to use a meticulous technique, and to perform an appropriate post-operative care, in order to decrease the complication rates. Copyright © 2016 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

  12. Radiographic Evaluation of the Ankle Mortise

    Directory of Open Access Journals (Sweden)

    Hamid Mirbagheri

    2010-05-01

    Full Text Available The ankle joint is the most frequently injured joint in adults. Decisions on management are usually based on clinical examination and interpretation of the x-rays. Stability of the ankle mortise relies on the configuration of the osseous structures and the ligaments. A basic radiographic examination consists of a mortise-view and a lateral view. Some add the AP-view. The Mortise view is an AP-view with 15-25 degrees endorotation of the foot. "nThe view clearly demonstrates both lateral and medial joint spaces. On a true AP-view the talus overlaps a portion of the lateral malleolus obscuring the lateral aspect of the ankle joint. However, the AP-view will give you an extra view on both malleoli from a different angle. The lateral radiograph of the ankle should include the base of the fifth metatarsal because of the frequency of fractures at this side that clinically mimic a fracture of the ankle.

  13. Tele-rehabilitation using in-house wearable ankle rehabilitation robot.

    Science.gov (United States)

    Jamwal, Prashant K; Hussain, Shahid; Mir-Nasiri, Nazim; Ghayesh, Mergen H; Xie, Sheng Q

    2016-09-22

    This article explores wide-ranging potential of the wearable ankle robot for in-house rehabilitation. The presented robot has been conceptualized following a brief analysis of the existing technologies, systems, and solutions for in-house physical ankle rehabilitation. Configuration design analysis and component selection for ankle robot have been discussed as part of the conceptual design. The complexities of human robot interaction are closely encountered while maneuvering a rehabilitation robot. We present a fuzzy logic-based controller to perform the required robot-assisted ankle rehabilitation treatment. Designs of visual haptic interfaces have also been discussed, which will make the treatment interesting, and the subject will be motivated to exert more and regain lost functions rapidly. The complex nature of web-based communication between user and remotely sitting physiotherapy staff has also been discussed. A high-level software architecture appended with robot ensures user-friendly operations. This software is made up of three important components: patient-related database, graphical user interface (GUI), and a library of exercises creating virtual reality-specifically developed for ankle rehabilitation.

  14. Analysis of the Effects of Normal Walking on Ankle Joint Contact Characteristics After Acute Inversion Ankle Sprain.

    Science.gov (United States)

    Bae, Ji Yong; Park, Kyung Soon; Seon, Jong Keun; Jeon, Insu

    2015-12-01

    To show the causal relationship between normal walking after various lateral ankle ligament (LAL) injuries caused by acute inversion ankle sprains and alterations in ankle joint contact characteristics, finite element simulations of normal walking were carried out using an intact ankle joint model and LAL injury models. A walking experiment using a volunteer with a normal ankle joint was performed to obtain the boundary conditions for the simulations and to support the appropriateness of the simulation results. Contact pressure and strain on the talus articular cartilage and anteroposterior and mediolateral translations of the talus were calculated. Ankles with ruptured anterior talofibular ligaments (ATFLs) had a higher likelihood of experiencing increased ankle joint contact pressures, strains and translations than ATFL-deficient ankles. In particular, ankles with ruptured ATFL + calcaneofibular ligaments and all ruptured ankles had a similar likelihood as the ATFL-ruptured ankles. The push off stance phase was the most likely situation for increased ankle joint contact pressures, strains and translations in LAL-injured ankles.

  15. Single leg balance test to identify risk of ankle sprains

    National Research Council Canada - National Science Library

    Trojian, T H; McKeag, D B

    2006-01-01

    .... The association between a positive SLB test and future ankle sprains was significant. Controlling for confounding variables, the relative risk for an ankle sprain with a positive SLB test was 2.54 (95...

  16. Laser application on haptics: Tactile stiffness measurement

    Science.gov (United States)

    Scalise, L.; Memeo, M.; Cannella, F.; Valente, M.; Caldwell, D. G.; Tomasini, E. P.

    2012-06-01

    There is a great interest in exploring the proprieties of the sense of the touch, its detailed knowledge in fact is a key issue in the area of robotics, haptics and human-machine interaction. In this paper, the authors focus their attention on a novel measurement method for the assessment of the tactile stiffness based on a original test rig; tactile stiffness is defined as the ratio between force, exerted by the finger, and the displacement of the finger tip operated during the test. To reach this scope, the paper describes a specific experimental test-rig used for the evaluation of subject tactile sensitivity, where finger force applied during tests as well as displacement and velocity of displacement, operated by the subject under investigation, are measured. Results show that tactile stiffness is linear respect to stimuli spatial difference (which is proportional to the difficulty to detect the variation of them). In particular, it has been possible to relate the force and displacement measured during the tests. The relationship between the response of the subject to the grating, velocity and force is determined. These results permit to carry out the further experimental tests on the same subject avoiding the use of a load cell and therefore simplifying the measurement test rig and data post-processing. Indeed, the first aspect (use of a load cell) can be relevant, because the grating positions are different, requiring a specific re-calibration and setting before each trial; while the second aspect allows simplify the test rig complexity and the processing algorithm.

  17. Bilateral ankle edema with bilateral iritis.

    Science.gov (United States)

    Kumar, Sunil

    2007-07-01

    I report two patient presented to me with bilateral symmetrical ankle edema and bilateral acute iritis. A 42-year-old female of Indian origin and 30-year-old female from Somalia both presented with bilateral acute iritis. In the first patient, bilateral ankle edema preceded the onset of bilateral acute iritis. Bilateral ankle edema developed during the course of disease after onset of ocular symptoms in the second patient. Both patients did not suffer any significant ocular problem in the past, and on systemic examination, all clinical parameters were within normal limit. Lacrimal gland and conjunctival nodule biopsy established the final diagnosis of sarcoidosis in both cases, although the chest x-rays were normal.

  18. Cutaneous mechanisms of isometric ankle force control

    DEFF Research Database (Denmark)

    Choi, Julia T; Jensen, Jesper Lundbye; Leukel, Christian

    2013-01-01

    output. We used repetitive electrical stimulation of the superficial peroneal (foot dorsum) and medial plantar nerves (foot sole) to disrupt cutaneous afferent input in 8 healthy subjects. We measured the effects of repetitive nerve stimulation on (1) tactile thresholds, (2) performance in an ankle force......-matching and (3) an ankle position-matching task. Additional force-matching experiments were done to compare the effects of transient versus continuous stimulation in 6 subjects and to determine the effects of foot anesthesia using lidocaine in another 6 subjects. The results showed that stimulation decreased...... of transient stimulation on force error were greater when compared to continuous stimulation and lidocaine injection. Position-matching performance was unaffected by peroneal nerve or plantar nerve stimulation. Our results show that cutaneous feedback plays a role in the control of force output at the ankle...

  19. Explicit Time-Stepping for Stiff ODEs

    CERN Document Server

    Eriksson, Kenneth; Logg, Anders; 10.1137/S1064827502409626

    2012-01-01

    We present a new strategy for solving stiff ODEs with explicit methods. By adaptively taking a small number of stabilizing small explicit time steps when necessary, a stiff ODE system can be stabilized enough to allow for time steps much larger than what is indicated by classical stability analysis. For many stiff problems the cost of the stabilizing small time steps is small, so the improvement is large. We illustrate the technique on a number of well-known stiff test problems.

  20. Technical advance: introducing a novel metric, directionality time, to quantify human neutrophil chemotaxis as a function of matrix composition and stiffness.

    Science.gov (United States)

    O'Brien, Xian M; Loosley, Alex J; Oakley, Katie E; Tang, Jay X; Reichner, Jonathan S

    2014-06-01

    A direct consequence of cellular movement and navigation, migration incorporates elements of speed, direction, and persistence of motion. Current techniques to parameterize the trajectory of a chemotaxing cell most commonly pair migration speed with some measure of persistence by calculating MSD, RMS speed, TAD, and/or CI. We address inherent limitations in TAD and CI for comparative analysis by introducing two new analytical tools to quantify persistence: directionality index and directionality time. With the use of these tools, we show that the mechanical properties of the underlying substrate contribute significantly to the regulation of human neutrophil chemotaxis toward fMLP on Fgn-, Col-, and Fn-coated gels of varying elasticity. The β₁-integrin ligand Col demonstrated mechanosensitive speed. In contrast, β₂-integrin ligand Fgn supported mechanosensitive persistence. Fn, recognized by β₁ and β₂ integrins, mechanoregulated speed and persistence. Blocking β₂ integrins of cells migrating on Fn identified an underlying β₂-integrin-directed modulation of persistence. These data demonstrate that individual components of the neutrophil chemotactic response show integrin dependence and are finely tunable with different ligand, mechanotactic, and chemotactic cues, underscoring the need for sensitive analytical methods.

  1. Elastic energy storage in leaf springs for a lever-arm based variable stiffness actuator

    NARCIS (Netherlands)

    Barrett, Eamon; Fumagalli, Matteo; Carloni, Raffaella

    2016-01-01

    The increasing use of Variable Stiffness Actuators (VSAs) in robotic joints is helping robots to meet the demands of human-robot interaction, requiring high safety and adaptability. The key feature of a VSA is the ability to exploit internal elastic elements to obtain a variable output stiffness.

  2. Elastic energy storage in leaf springs for a lever-arm based variable stiffness actuator

    NARCIS (Netherlands)

    Barrett, Eamon; Fumagalli, Matteo; Carloni, Raffaella

    2016-01-01

    The increasing use of Variable Stiffness Actuators (VSAs) in robotic joints is helping robots to meet the demands of human-robot interaction, requiring high safety and adaptability. The key feature of a VSA is the ability to exploit internal elastic elements to obtain a variable output stiffness. Th

  3. Sport stretching : Effect on passive muscle stiffness of short hamstrings

    NARCIS (Netherlands)

    Halbertsma, JPK; vanBolhuis, AI; Goeken, LNH

    1996-01-01

    Objective: To evaluate the effects of one 10-minute stretch on muscle stiffness in subjects with short hamstrings. Design: Randomized control trial. Setting: Laboratory for human movement sciences in the department of rehabilitation of a university hospital. Subjects: Sixteen students from the Depar

  4. Management of Osseous and Soft-Tissue Ankle Equinus During Total Ankle Replacement.

    Science.gov (United States)

    Roukis, Thomas S; Simonson, Devin C

    2015-10-01

    Obtaining functional alignment of a total ankle replacement, including physiologic sagittal plane range of motion, is paramount for a successful outcome. This article reviews the literature on techniques available for correction of osseous and soft-tissue equinus at the time of index total ankle replacement. These techniques include anterior tibiotalar joint cheilectomy, posterior superficial muscle compartment lengthening, posterior ankle capsule release, and release of the posterior portions of the medial and lateral collateral ligament complexes. The rationale for these procedures and the operative sequence of events for these procedures are presented.

  5. Substrate stiffness regulates filopodial activities in lung cancer cells.

    Directory of Open Access Journals (Sweden)

    Yu-Ren Liou

    Full Text Available Microenvironment stiffening plays a crucial role in tumorigenesis. While filopodia are generally thought to be one of the cellular mechanosensors for probing environmental stiffness, the effects of environmental stiffness on filopodial activities of cancer cells remain unclear. In this work, we investigated the filopodial activities of human lung adenocarcinoma cells CL1-5 cultured on substrates of tunable stiffness using a novel platform. The platform consists of an optical system called structured illumination nano-profilometry, which allows time-lapsed visualization of filopodial activities without fluorescence labeling. The culturing substrates were composed of polyvinyl chloride mixed with an environmentally friendly plasticizer to yield Young's modulus ranging from 20 to 60 kPa. Cell viability studies showed that the viability of cells cultured on the substrates was similar to those cultured on commonly used elastomers such as polydimethylsiloxane. Time-lapsed live cell images were acquired and the filopodial activities in response to substrates with varying degrees of stiffness were analyzed. Statistical analyses revealed that lung cancer cells cultured on softer substrates appeared to have longer filopodia, higher filopodial densities with respect to the cellular perimeter, and slower filopodial retraction rates. Nonetheless, the temporal analysis of filopodial activities revealed that whether a filopodium decides to extend or retract is purely a stochastic process without dependency on substrate stiffness. The discrepancy of the filopodial activities between lung cancer cells cultured on substrates with different degrees of stiffness vanished when the myosin II activities were inhibited by treating the cells with blebbistatin, which suggests that the filopodial activities are closely modulated by the adhesion strength of the cells. Our data quantitatively relate filopodial activities of lung cancer cells with environmental stiffness and

  6. Shoulder Stiffness : Current Concepts and Concerns

    NARCIS (Netherlands)

    Itoi, Eiji; Arce, Guillermo; Bain, Gregory I.; Diercks, Ronald L.; Guttmann, Dan; Imhoff, Andreas B.; Mazzocca, Augustus D.; Sugaya, Hiroyuki; Yoo, Yon-Sik

    2016-01-01

    Shoulder stiffness can be caused by various etiologies such as immobilization, trauma, or surgical interventions. The Upper Extremity Committee of ISAKOS defined the term "frozen shoulder" as idiopathic stiff shoulder, that is, without a known cause. Secondary stiff shoulder is a term that should be

  7. Energy-Efficient Variable Stiffness Actuators

    NARCIS (Netherlands)

    Visser, Ludo C.; Carloni, Raffaella; Stramigioli, Stefano

    2011-01-01

    Variable stiffness actuators are a particular class of actuators that is characterized by the property that the apparent output stiffness can be changed independent of the output position. To achieve this, variable stiffness actuators consist of a number of elastic elements and a number of actuated

  8. Foot and Ankle Injuries in American Football.

    Science.gov (United States)

    Hsu, Andrew R; Anderson, Robert B

    Physicians need to be aware of a variety of foot and ankle injuries that commonly occur in American football, including turf toe, Jones fractures, Lisfranc injuries, syndesmotic and deltoid disruption, and Achilles ruptures. These injuries are often complex and require early individual tailoring of treatment and rehabilitation protocols. Successful management and return to play requires early diagnosis, a thorough work-up, and prompt surgical intervention when warranted with meticulous attention to restoration of normal foot and ankle anatomy. Physicians should have a high suspicion for subtle injuries and variants that can occur via both contact and noncontact mechanisms.

  9. Characterization of ankle function during stair ambulation

    OpenAIRE

    Gates, Deanna H.; Lelas, Jennifer L.; Della Croce, Ugo; Herr, Hugh; Bonato, Paolo

    2004-01-01

    The aim of this study was to examine the ankle joint during level walking, stair ascent, and stair descent to determine models for use in the design of prosthetic and orthotic systems. Ten healthy subjects were asked to walk (1) across a level walkway, (2) up, and (3) down an instrumented stairway. Sagittal plane kinematic and kinetic data were analyzed to obtain ankle biomechanics during the stance phase of each task. Each stance phase was broken down into sub-phases based on the power traje...

  10. Ankle fusion using a 2-incision, 3-screw technique

    NARCIS (Netherlands)

    R.P.M. Hendrickx; G.M.M.J. Kerkhoffs; S.A.S. Stufkens; C.N. van Dijk; R.K. Marti

    2011-01-01

    Reliable fusion and optimal correction of the alignment of the ankle joint using a 2-incision, 3-screw technique. Symptomatic osteoarthritis of the ankle joint after insufficient other treatment, severe deformity of the osteoarthritic ankle joint, or salvation procedure after failed arthroplasty. Ac

  11. Lower-limb amputee ankle and hip kinetic response to an imposed error in mediolateral foot placement.

    Science.gov (United States)

    Segal, Ava D; Shofer, Jane B; Klute, Glenn K

    2015-11-26

    Maintaining balance while walking is challenging for lower limb amputees. The effect of prosthetic foot stiffness on recovery kinetics from an error in foot placement may inform prescription practice and lead to new interventions designed to improve balance. Ten unilateral transtibial amputees were fit with two prosthetic feet with different stiffness properties in random order. After a 3-week acclimation period, they returned to the lab for testing before switching feet. Twelve non-amputees also participated in a single data collection. While walking on an instrumented treadmill, we imposed a repeatable, unexpected medial or lateral disturbance in foot placement by releasing a burst of air at the ankle just before heel strike. Three-dimensional motion capture, ground reaction force and center of pressure (COP) data were collected for two steps prior, the disturbed step and three steps after the disturbance. During undisturbed walking, coronal ankle impulse was lower by 42% for amputees wearing a stiff compared to a compliant foot (p=0.017); however, across steps, both prosthetic recovery patterns were similar compared to the sound limb and non-amputees. Peak coronal hip moment was 15-20% lower for both foot types during undisturbed walking (pamputees. Amputee prosthetic COP excursion was unaffected by the disturbance (2.4% change) compared to the sound limb (59% change; pamputees (55% change; pamputees.

  12. Negative stiffness in gear contact

    Directory of Open Access Journals (Sweden)

    Půst L.

    2015-12-01

    Full Text Available The tooth contact stiffness is very often included in dynamic mathematical models of gear drives. It is an important value for calculation of torsion eigenfrequencies as well as the dynamic properties of the whole transmission systems. Planetary gear drives have several advantages over simple parallel axis gears, especially due to theirs compact design and great torque-to-weight ratio caused by multiple parallel paths. However, the dimensional or mounting errors can cause that some planets have the tendency to take more load than the others. One of the ways how to improve load sharing is the application of flexible planetary pins or by using a free central wheel. However in such cases, the wheels motion is defined in one rotation coordinate and two translation coordinates — tangential and radial. The reaction force at radial change of axis distance is usually neglected. The focus of this contribution is to derive the stiffness of this radial connection and to analyse the influence of radial stiffness on planetary gear dynamics.

  13. Low-intensity resistance training after high-intensity resistance training can prevent the increase of central arterial stiffness.

    Science.gov (United States)

    Okamoto, T; Masuhara, M; Ikuta, K

    2013-05-01

    Although high-intensity resistance training increases arterial stiffness, low-intensity resistance training reduces arterial stiffness. The present study investigates the effect of low-intensity resistance training before and after high-intensity resistance training on arterial stiffness. 30 young healthy subjects were randomly assigned to a group that performed low-intensity resistance training before high-intensity resistance training (BLRT, n=10), a group that performed low-intensity resistance training after high-intensity resistance training (ALRT, n=10) and a sedentary control group (n=10). The BLRT and ALRT groups performed resistance training at 80% and 50% of one repetition maximum twice each week for 10 wk. Arterial stiffness was measured using carotid-femoral and femoral-ankle pulse wave velocity (PWV). One-repetition maximum strength in the both ALRT and BLRT significantly increased after the intervention (Ptraining in the ALRT group did not change from before training. In contrast, carotid-femoral PWV after combined training in the BLRT group increased from before training (P training in the both BLRT and ALRT groups did not change from before training. These results suggest that although arterial stiffness is increased by low-intensity resistance training before high-intensity resistance training, performing low-intensity resistance training thereafter can prevent the increase of arterial stiffness. © Georg Thieme Verlag KG Stuttgart · New York.

  14. Recalcitrant Lateral Premalleolar Bursitis of the Ankle Associated with Lateral Ankle Instability

    Directory of Open Access Journals (Sweden)

    Masashi Naito

    2017-01-01

    Full Text Available Lateral premalleolar bursitis of the ankle is a rarely reported disorder in the English literature although it is not uncommon in Asian countries where people commonly sit on their feet. Here, we present the case of a 66-year-old woman with recalcitrant lateral premalleolar bursitis associated with lateral ankle instability which was successfully treated with surgical resection of the bursa and repair of the anterior talofibular ligament. Operative findings revealed a communication between the bursa and articular cavity of the ankle joint via the sheath of the extensor digitorum longus tendon, which was considered to act as a check valve leading to a large and recalcitrant bursitis. This report provides a novel concept about the etiology of recalcitrant lateral premalleolar bursitis of the ankle.

  15. Therapeutic Interventions for Increasing Ankle Dorsiflexion After Ankle Sprain: A Systematic Review

    Science.gov (United States)

    Terada, Masafumi; Pietrosimone, Brian G.; Gribble, Phillip A.

    2013-01-01

    Context: Clinicians perform therapeutic interventions, such as stretching, manual therapy, electrotherapy, ultrasound, and exercises, to increase ankle dorsiflexion. However, authors of previous studies have not determined which intervention or combination of interventions is most effective. Objective: To determine the magnitude of therapeutic intervention effects on and the most effective therapeutic interventions for restoring normal ankle dorsiflexion after ankle sprain. Data Sources: We performed a comprehensive literature search in Web of Science and EBSCO HOST from 1965 to May 29, 2011, with 19 search terms related to ankle sprain, dorsiflexion, and intervention and by cross-referencing pertinent articles. Study Selection: Eligible studies had to be written in English and include the means and standard deviations of both pretreatment and posttreatment in patients with acute, subacute, or chronic ankle sprains. Outcomes of interest included various joint mobilizations, stretching, local vibration, hyperbaric oxygen therapy, electrical stimulation, and mental-relaxation interventions. Data Extraction: We extracted data on dorsiflexion improvements among various therapeutic applications by calculating Cohen d effect sizes with associated 95% confidence intervals (CIs) and evaluated the methodologic quality using the Physiotherapy Evidence Database (PEDro) scale. Data Synthesis: In total, 9 studies (PEDro score = 5.22 ± 1.92) met the inclusion criteria. Static-stretching interventions with a home exercise program had the strongest effects on increasing dorsiflexion in patients 2 weeks after acute ankle sprains (Cohen d = 1.06; 95% CI = 0.12, 2.42). The range of effect sizes for movement with mobilization on ankle dorsiflexion among individuals with recurrent ankle sprains was small (Cohen d range = 0.14 to 0.39). Conclusions: Static-stretching intervention as a part of standardized care yielded the strongest effects on dorsiflexion after acute ankle sprains. The

  16. Telemetric ambulatory arterial stiffness index, a predictor of cardio-cerebro-vascular mortality, is associated with aortic stiffness-determining factors.

    Science.gov (United States)

    Li, Zhi-Yong; Xu, Tian-Ying; Zhang, Sai-Long; Zhou, Xiao-Ming; Xu, Xue-Wen; Guan, Yun-Feng; Lo, Ming; Miao, Chao-Yu

    2013-09-01

    Ambulatory arterial stiffness index (AASI) has been proposed as a new measure of arterial stiffness for predicting cardio-cerebro-vascular morbidity and mortality. However, there has been no research on the direct relationships between AASI and arterial stiffness-determining factors. We utilized beat-to-beat intra-aortic blood pressure (BP) telemetry to characterize AASI in Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). By determination of aortic structural components and analysis of their correlations with AASI, we provided the first direct evidence for the associations between AASI and arterial stiffness-determining factors including the collagen content and collagen/elastin. Ambulatory arterial stiffness index was positively correlated with pulse pressure in both WKY and SHR, less dependent on BP and BP variability than pulse pressure, and relatively stable, especially the number of BP readings not less than ~36. The correlations between AASI and aortic components were comparable for various AASI values derived from BP readings not less than ~36. Not only AASI but also BP variability and pulse pressure demonstrated a direct relationship with arterial stiffness. These findings indicate AASI may become a routine measure in human arterial stiffness assessment. It is recommended to use a cluster of parameters such as AASI, BP variability, and pulse pressure for evaluating arterial stiffness. © 2013 John Wiley & Sons Ltd.

  17. Short-term ankle motor performance with ankle robotics training in chronic hemiparetic stroke.

    Science.gov (United States)

    Roy, Anindo; Forrester, Larry W; Macko, Richard F

    2011-01-01

    Cerebrovascular accident (stroke) often results in impaired motor control and persistent weakness that may lead to chronic disability, including deficits in gait and balance function. Finding ways to restore motor control may help reduce these deficits; however, little is known regarding the capacity or temporal profile of short-term motor adaptations and learning at the hemiparetic ankle. Our objective was to determine the short-term effects of a single session of impedance-controlled ankle robot ("anklebot") training on paretic ankle motor control in chronic stroke. This was a double-arm pilot study on a convenience sample of participants with chronic stroke (n = 7) who had residual hemiparetic deficits and an equal number of age- and sex-matched nondisabled control subjects. Training consisted of participants in each group playing a target-based video game with the anklebot for an hour, for a total of 560 movement repetitions in dorsiflexion/plantar flexion ranges followed by retest 48 hours later. Task difficulty was adjusted to ankle range of motion, with robotic assistance decreased incrementally across training. Assessments included robotic measures of ankle motor control on unassisted trials before and after training and at 48 hours after training. Following exposure to the task, subjects with stroke improved paretic ankle motor control across a single training session as indexed by increased targeting accuracy (21.6 +/- 8.0 to 31.4 +/- 4.8, p = 0.05), higher angular speeds (mean: 4.7 +/- 1.5 degrees/s to 6.5 +/- 2.6 degrees/s, p 0.05) at 48 hours in both groups. Robust maintenance of motor adaptation in the robot-trained paretic ankle over 48 hours may be indicative of short-term motor learning. Our initial results suggest that the anklebot may be a flexible motor learning platform with the potential to detect rapid changes in ankle motor performance poststroke.

  18. Short-term ankle motor performance with ankle robotics training in chronic hemiparetic stroke

    Directory of Open Access Journals (Sweden)

    Anindo Roy, PhD

    2011-05-01

    Full Text Available Cerebrovascular accident (stroke often results in impaired motor control and persistent weakness that may lead to chronic disability, including deficits in gait and balance function. Finding ways to restore motor control may help reduce these deficits; however, little is known regarding the capacity or temporal profile of short-term motor adaptations and learning at the hemiparetic ankle. Our objective was to determine the short-term effects of a single session of impedance-controlled ankle robot (“anklebot” training on paretic ankle motor control in chronic stroke. This was a double-arm pilot study on a convenience sample of participants with chronic stroke (n = 7 who had residual hemiparetic deficits and an equal number of age- and sex-matched nondisabled control subjects. Training consisted of participants in each group playing a target-based video game with the anklebot for an hour, for a total of 560 movement repetitions in dorsiflexion/plantar flexion ranges followed by retest 48 hours later. Task difficulty was adjusted to ankle range of motion, with robotic assistance decreased incrementally across training. Assessments included robotic measures of ankle motor control on unassisted trials before and after training and at 48 hours after training. Following exposure to the task, subjects with stroke improved paretic ankle motor control across a single training session as indexed by increased targeting accuracy (21.6 +/– 8.0 to 31.4 +/– 4.8, p = 0.05, higher angular speeds (mean: 4.7 +/– 1.5 degrees/s to 6.5 +/– 2.6 degrees/s, p 0.05 at 48 hours in both groups. Robust maintenance of motor adaptation in the robot-trained paretic ankle over 48 hours may be indicative of short-term motor learning. Our initial results suggest that the anklebot may be a flexible motor learning platform with the potential to detect rapid changes in ankle motor performance poststroke.

  19. An examination of ankle, knee, and hip torque production in individuals with chronic ankle instability.

    Science.gov (United States)

    Gribble, Phillip A; Robinson, Richard H

    2009-03-01

    There is some debate in the literature as to whether strength deficits exist at the ankle in individuals with chronic ankle instability (CAI). Additionally, there is evidence to suggest that knee and hip performance is altered in those with CAI. Therefore, the purpose of this study was to determine whether CAI is associated with deficits in ankle, knee, and hip torque. Fifteen subjects with unilateral CAI and fifteen subjects with healthy ankles participated. Subjects reported to the laboratory for one session during which the torque production of ankle plantar flexion/dorsiflexion, knee flexion/extension, and hip flexion/extension were measured with an isokinetic device. Subjects performed 5 maximum-effort repetitions of a concentric/concentric protocol at 60 degrees .s for both extremities. Average peak torque (APT) values were calculated. The subjects with CAI demonstrated significantly less APT production for knee flexion (F1,28 = 5.40; p = 0.03) and extension (F1,28 = 5.34; p = 0.03). Subjects with CAI exhibited significantly less APT for ankle plantar flexion in the injured limb compared with their noninjured limb (F1,28 = 6.51; p = 0.02). No significant difference in ankle dorsiflexion or hip flexion/extension APT production existed between the 2 groups. Individuals with CAI, in addition to deficits in ankle plantar flexion torque, had deficits in knee flexor and extensor torque, suggesting that distal joint instability may lead to knee joint neuromuscular adaptations. There were no similar deficits at the hip. Future research should determine what implications this has for prevention and rehabilitation of lower-extremity injury. Clinicians may need to consider including rehabilitation efforts to address these deficits when rehabilitating patients with CAI.

  20. Measurement and Treatment of Passive Muscle Stiffness

    DEFF Research Database (Denmark)

    Kirk, Henrik

    This PhD thesis is based on research conducted at the University of Copenhagen and Helene Elsass Center from 2012 to 2015. Measurements and treatment of passive muscle stiffness in people with cerebral palsy (CP) comprise the focus of the thesis. The thesis summarizes the results from four studies...... stiffness. I introduce how to evaluate and distinguish between passive muscle stiffness and reflex-mediated stiffness in research and in clinical practice. Furthermore, I present ”the Portable Spasticity Assessment Device”, which was developed as a part of the PhD study. I discuss the validity......-mediated stiffness was considered a major problem. However, this study shows that significantly reduced RFD and increased passive muscle stiffness, rather than reflex-mediated stiffness, are the major contributors to impaired gait function in adults with CP, compared with neurologically healthy subjects. The third...

  1. Passive stiffness of hindlimb muscles in anurans with distinct locomotor specializations.

    Science.gov (United States)

    Danos, Nicole; Azizi, Emanuel

    2015-08-01

    Anurans (frogs and toads) have been shown to have relatively compliant skeletal muscles. Using a meta-analysis of published data we have found that muscle stiffness is negatively correlated with joint range of motion when examined across mammalian, anuran and bird species. Given this trend across a broad phylogenetic sample, we examined whether the relationship held true within anurans. We identified four species that differ in preferred locomotor mode and hence joint range of motion (Lithobates catesbeianus, Rhinella marina, Xenopus laevis and Kassina senegalensis) and hypothesized that smaller in vivo angles (more flexed) at the knee and ankle joint would be associated with more compliant extensor muscles. We measured passive muscle tension during cyclical stretching (20%) around L0 (sarcomere lengths of 2.2 μm) in fiber bundles extracted from cruralis and plantaris muscles. We found no relationship between muscle stiffness and range of motion for either muscle-joint complex. There were no differences in the passive properties of the cruralis muscle among the four species, but the plantaris muscles of the Xenopus and Kassina were significantly stiffer than those of the other two species. Our results suggest that in anurans the stiffness of muscle fibers is a relatively minor contributor to stiffness at the level of joints and that variation in other anatomical properties including muscle-tendon architecture and joint mechanics as well as active control likely contribute more significantly to range of motion during locomotion. Copyright © 2015 Elsevier GmbH. All rights reserved.

  2. Cutaneous mechanisms of isometric ankle force control.

    Science.gov (United States)

    Choi, Julia T; Lundbye-Jensen, Jesper; Leukel, Christian; Nielsen, Jens Bo

    2013-07-01

    The sense of force is critical in the control of movement and posture. Multiple factors influence our perception of exerted force, including inputs from cutaneous afferents, muscle afferents and central commands. Here, we studied the influence of cutaneous feedback on the control of ankle force output. We used repetitive electrical stimulation of the superficial peroneal (foot dorsum) and medial plantar nerves (foot sole) to disrupt cutaneous afferent input in 8 healthy subjects. We measured the effects of repetitive nerve stimulation on (1) tactile thresholds, (2) performance in an ankle force-matching and (3) an ankle position-matching task. Additional force-matching experiments were done to compare the effects of transient versus continuous stimulation in 6 subjects and to determine the effects of foot anesthesia using lidocaine in another 6 subjects. The results showed that stimulation decreased cutaneous sensory function as evidenced by increased touch threshold. Absolute dorsiflexion force error increased without visual feedback during peroneal nerve stimulation. This was not a general effect of stimulation because force error did not increase during plantar nerve stimulation. The effects of transient stimulation on force error were greater when compared to continuous stimulation and lidocaine injection. Position-matching performance was unaffected by peroneal nerve or plantar nerve stimulation. Our results show that cutaneous feedback plays a role in the control of force output at the ankle joint. Understanding how the nervous system normally uses cutaneous feedback in motor control will help us identify which functional aspects are impaired in aging and neurological diseases.

  3. Malignant melanoma of the foot and ankle.

    Science.gov (United States)

    John, K J; Hayes, D W; Green, D R; Dickerson, J

    2000-04-01

    Malignant melanoma is a serious and devastating skin disease that podiatrists may be called upon to treat. It is pertinent that delays in diagnosis and treatment of malignant melanoma be avoided. Some of the topics discussed in this article are causes, clinical features, classification, and treatment of malignant melanoma, focusing on the foot and ankle.

  4. Hip-ankle coordination during gait in individuals with chronic ankle instability.

    Science.gov (United States)

    Yen, Sheng-Che; Chui, Kevin K; Corkery, Marie B; Allen, Elizabeth A; Cloonan, Caitlin M

    2017-03-01

    Individuals with chronic ankle instability (CAI) may have sensorimotor impairments that affect control at the hip in addition to the ankle. The purpose of this study was to compare hip-ankle coordination and coordination variability between individuals with CAI and healthy individuals during walking. Ten healthy subjects and 10 subjects with CAI were recruited to walk on a treadmill. Hip-ankle coordination was quantified using vector coding, and coordination variability was quantified using coefficient of correspondence. We found significant between-group differences in hip-ankle coordination in the frontal plane around loading response (Control: 165.9±18.4°; CAI: 127.6±48.6°, p=0.04) and in the sagittal plane around the first half of mid stance (Control: 307.2±9.8°; CAI: 291.8±11.4°, pcoordination variability in the frontal plane around the second half of mid stance (Control: 0.54±0.06; CAI: 0.45±0.07, Pcoordination and coordination variability in stance phase during walking. Gait training is important in CAI rehabilitation, and the training should address altered hip-ankle coordination to reduce the risk of recurrent injuries. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Powered ankle-foot prosthesis to assist level-ground and stair-descent gaits.

    Science.gov (United States)

    Au, Samuel; Berniker, Max; Herr, Hugh

    2008-05-01

    The human ankle varies impedance and delivers net positive work during the stance period of walking. In contrast, commercially available ankle-foot prostheses are passive during stance, causing many clinical problems for transtibial amputees, including non-symmetric gait patterns, higher gait metabolism, and poorer shock absorption. In this investigation, we develop and evaluate a myoelectric-driven, finite state controller for a powered ankle-foot prosthesis that modulates both impedance and power output during stance. The system employs both sensory inputs measured local to the external prosthesis, and myoelectric inputs measured from residual limb muscles. Using local prosthetic sensing, we first develop two finite state controllers to produce biomimetic movement patterns for level-ground and stair-descent gaits. We then employ myoelectric signals as control commands to manage the transition between these finite state controllers. To transition from level-ground to stairs, the amputee flexes the gastrocnemius muscle, triggering the prosthetic ankle to plantar flex at terminal swing, and initiating the stair-descent state machine algorithm. To transition back to level-ground walking, the amputee flexes the tibialis anterior muscle, triggering the ankle to remain dorsiflexed at terminal swing, and initiating the level-ground state machine algorithm. As a preliminary evaluation of clinical efficacy, we test the device on a transtibial amputee with both the proposed controller and a conventional passive-elastic control. We find that the amputee can robustly transition between the finite state controllers through direct muscle activation, allowing rapid transitioning from level-ground to stair walking patterns. Additionally, we find that the proposed finite state controllers result in a more biomimetic ankle response, producing net propulsive work during level-ground walking and greater shock absorption during stair descent. The results of this study highlight the

  6. Chronic ankle instability: Arthroscopic anatomical repair.

    Science.gov (United States)

    Arroyo-Hernández, M; Mellado-Romero, M; Páramo-Díaz, P; García-Lamas, L; Vilà-Rico, J

    Ankle sprains are one of the most common injuries. Despite appropriate conservative treatment, approximately 20-40% of patients continue to have chronic ankle instability and pain. In 75-80% of cases there is an isolated rupture of the anterior talofibular ligament. A retrospective observational study was conducted on 21 patients surgically treated for chronic ankle instability by means of an arthroscopic anatomical repair, between May 2012 and January 2013. There were 15 men and 6 women, with a mean age of 30.43 years (range 18-48). The mean follow-up was 29 months (range 25-33). All patients were treated by arthroscopic anatomical repair of anterior talofibular ligament. Four (19%) patients were found to have varus hindfoot deformity. Associated injuries were present in 13 (62%) patients. There were 6 cases of osteochondral lesions, 3 cases of posterior ankle impingement syndrome, and 6 cases of peroneal pathology. All these injuries were surgically treated in the same surgical time. A clinical-functional study was performed using the American Orthopaedic Foot and Ankle Society (AOFAS) score. The mean score before surgery was 66.12 (range 60-71), and after surgery it increased up to a mean of 96.95 (range 90-100). All patients were able to return to their previous sport activity within a mean of 21.5 weeks (range 17-28). Complications were found in 3 (14%) patients. Arthroscopic anatomical ligament repair technique has excellent clinical-functional results with a low percentage of complications, and enables patients to return to their previous sport activity within a short period of time. Copyright © 2016 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Total Ankle Arthroplasty: An Overview of the Canadian Experience.

    Science.gov (United States)

    Latham, Warren C W; Lau, Johnny T C

    2016-06-01

    Total ankle arthroplasty use has increased across Canada over the last two decades. Multiple implant designs are readily available and implanted across Canada. Although arthrodesis is a reliable procedure for treating end-stage ankle arthritis, ankle replacement is often the preferred surgical treatment by patients. A recent prospective study evaluated intermediate-term outcomes of ankle replacement and arthrodesis at multiple centers across Canada, with variability in prosthesis type, surgeon, and surgical technique. Intermediate-term clinical outcomes of total ankle replacement and ankle arthrodesis were comparable in a diverse cohort in which treatment was tailored to patient presentation; however, rates of reoperation and major complications were higher after ankle replacement.

  8. Measuring Ankle Instability in Pediatric Charcot-Marie-Tooth Disease.

    Science.gov (United States)

    Mandarakas, Melissa; Hiller, Claire E; Rose, Kristy J; Burns, Joshua

    2013-11-01

    Children with Charcot-Marie-Tooth disease frequently suffer ankle sprain and experience chronic ankle instability; however, no pediatric self-reported measures of chronic ankle instability exist. The aim was to modify and validate the most reliable measure of chronic ankle instability in adults: the Cumberland Ankle Instability Tool. The Cumberland Ankle Instability Tool-Youth was tested for reliability, construct validity, and sensitivity to discriminate between 104 children aged 8 to 16 years: 31 children with Charcot-Marie-Tooth disease, 31 unaffected children with a history of ankle sprains, and 42 controls. Children with Charcot-Marie-Tooth disease had lower scores compared to unaffected children with a history of sprains (χ(2) = 15.10; P Charcot-Marie-Tooth disease.

  9. State of the art review of knee-ankle-foot orthoses.

    Science.gov (United States)

    Tian, Feng; Hefzy, Mohamed Samir; Elahinia, Mohammad

    2015-02-01

    Knee-ankle-foot orthoses (KAFOs) are used to assist in ambulation. The purpose of this paper is to review existing KAFO designs which can be grouped into passive KAFOs, stance control (SC) KAFOs, and dynamic KAFOs. The conventional passive KAFOs do not provide any active control for knee motions. SCKAFOs lock the knee joint during the stance phase and allow free rotations during the swing phase. Some SCKAFOs switch between the stance and swing phases using body posture, while others use some kind of a control system to perform this switch. Finally, dynamic KAFOs control the knee joint during both stance and swing phases. Four dynamic systems are identified in the literature that use pneumatics, linear springs, hydraulics, and torsional rods made of superelastic alloys to control the knee joint during the gait cycle. However, only the two systems that use linear springs and torsional rods can reproduce the normal knee stiffness pattern which has two distinct characteristics: a soft stiffness during the swing phase and a hard stiffness during the stance phase. This review indicates that there is a need to conduct research regarding new KAFO designs that duplicate normal knee function during the whole gait cycle.

  10. Spastic paretic stiff-legged gait: biomechanics of the unaffected limb.

    Science.gov (United States)

    Kerrigan, D C; Frates, E P; Rogan, S; Riley, P O

    1999-01-01

    A concern for individuals with hemiparesis affecting their gait, which heretofore has never been studied, is the possibility that various compensations occurring in the unaffected limb may strain or fatigue the muscles or ligaments and/or predispose to joint injury in that limb. We studied the biomechanics of the unaffected limb during walking in 20 subjects with hemiparesis who had stiff-legged gait as a result of stroke. An optoelectronic motion analysis and force platform system was used to estimate torques in all three planes about the hip, knee, and ankle. Sagittal plane joint motion and power about the unaffected hip, knee, and ankle were also studied. Data were compared with control walking data collected from 20 able-bodied controls. On average, peak torques and powers were all either reduced or the same compared with controls, even though in some instances values were >2 standard deviations (SD) above the control means. Our findings suggest that on average the probability of excessive muscular-tendon effort and the risk for biomechanical injury in the unaffected limb are minimal compared with able-bodied, walking controls. However, given individual variability, we recommend routine clinical gait analysis for all people with stiff-legged gait to eliminate excessive values in certain biomechanical parameters, which could, if not addressed, predispose to muscle-tendon strain or joint or ligamentous injury.

  11. No change in calf muscle passive stiffness after botulinum toxin injection in children with cerebral palsy.

    Science.gov (United States)

    Alhusaini, Adel A A; Crosbie, Jack; Shepherd, Roberta B; Dean, Catherine M; Scheinberg, Adam

    2011-06-01

    Stiffness and shortening of the calf muscle due to neural or mechanical factors can profoundly affect motor function. The aim of this study was to investigate non-neurally mediated calf-muscle tightness in children with cerebral palsy (CP) before and after botulinum toxin type A (BoNT-A) injection. Sixteen children with spastic CP (seven females, nine males; eight at Gross Motor Function Classification System level I, eight at level II; age range 4-10 y) and calf muscle spasticity were tested before and during the pharmaceutically active phase after injection of BoNT-A. Measures of passive muscle compliance and viscoelastic responses, hysteresis, and the gradient of the torque-angle curve were computed and compared before and after injection. Although there was a slight, but significant increase in ankle range of motion after BoNT-A injection and a small, significant decrease in the torque required to achieve plantigrade and 5° of dorsiflexion, no significant difference in myotendinous stiffness or hysteresis were detected after BoNT-A injection. Despite any effect on neurally mediated responses, the compliance of the calf muscle was not changed and the muscle continued to offer significant resistance to passive motion of the ankle. These findings suggest that additional treatment approaches are required to supplement the effects of BoNT-A injections when managing children with calf muscle spasticity. © The Authors. Developmental Medicine & Child Neurology © 2011 Mac Keith Press.

  12. Effect of External Ankle Support on Ankle and Knee Biomechanics During the Cutting Maneuver in Basketball Players.

    Science.gov (United States)

    Klem, Nardia-Rose; Wild, Catherine Y; Williams, Sian A; Ng, Leo

    2017-03-01

    Despite the high prevalence of lower extremity injuries in female basketball players as well as a high proportion of athletes who wear ankle braces, there is a paucity of research pertaining to the effects of ankle bracing on ankle and knee biomechanics during basketball-specific tasks. To compare the effects of a lace-up brace (ASO), a hinged brace (Active T2), and no ankle bracing (control) on ankle and knee joint kinematics and joint reaction forces in female basketball athletes during a cutting maneuver. Controlled laboratory study. Twenty healthy, semi-elite female basketball players performed a cutting task under both ankle brace conditions (lace-up ankle brace and hinged ankle brace) and a no-brace condition. The 3-dimensional kinematics of the ankle and knee during the cutting maneuver were measured with an 18-camera motion analysis system (250 Hz), and ground-reaction force data were collected by use of a multichannel force plate (2000 Hz) to quantify ankle and knee joint reaction forces. Conditions were randomized using a block randomization method. Compared with the control condition, the hinged ankle brace significantly restricted peak ankle inversion (mean difference, 1.7°; P = .023). No significant difference was found between the lace-up brace and the control condition ( P = .865). Compared with the lace-up brace, the hinged brace significantly reduced ankle and knee joint compressive forces at the time of peak ankle dorsiflexion (mean difference, 1.5 N/kg [ P = .018] and 1.4 N/kg [ P = .013], respectively). Additionally, the hinged ankle brace significantly reduced knee anterior shear forces compared with the lace-up brace both during the deceleration phase and at peak ankle dorsiflexion (mean difference, 0.8 N/kg [ P = .018] and 0.9 N/kg [ P = .011], respectively). The hinged ankle brace significantly reduced ankle inversion compared with the no-brace condition and reduced ankle and knee joint forces compared with the lace-up brace in a female

  13. Explosive resistance training increases rate of force development in ankle dorsiflexors and gait function in adults with cerebral palsy

    DEFF Research Database (Denmark)

    Kirk, Henrik; Geertsen, Svend Sparre; Lorentzen, Jakob

    2016-01-01

    Alterations in passive elastic properties of muscles and reduced ability to quickly generate muscle force contribute to impaired gait function in adults with cerebral palsy (CP). Here, we investigated if 12 weeks of progressive and explosive resistance training (PRT) increases rate of force...... dorsiflexion, plantarflexion, leg press, hamstring curls, abdominal curls and back extension 3 days/week for 12 weeks, with 3 sets per exercise and progressing during the training period from 12-6 RM. RFDdf, 3-D gait analysis, functional performance and ankle joint passive- and reflex-mediated muscle stiffness...

  14. Muscle recruitment and coordination with an ankle exoskeleton.

    Science.gov (United States)

    Steele, Katherine M; Jackson, Rachel W; Shuman, Benjamin R; Collins, Steven H

    2017-07-05

    Exoskeletons have the potential to assist and augment human performance. Understanding how users adapt their movement and neuromuscular control in response to external assistance is important to inform the design of these devices. The aim of this research was to evaluate changes in muscle recruitment and coordination for ten unimpaired individuals walking with an ankle exoskeleton. We evaluated changes in the activity of individual muscles, cocontraction levels, and synergistic patterns of muscle coordination with increasing exoskeleton work and torque. Participants were able to selectively reduce activity of the ankle plantarflexors with increasing exoskeleton assistance. Increasing exoskeleton net work resulted in greater reductions in muscle activity than increasing exoskeleton torque. Patterns of muscle coordination were not restricted or constrained to synergistic patterns observed during unassisted walking. While three synergies could describe nearly 95% of the variance in electromyography data during unassisted walking, these same synergies could describe only 85-90% of the variance in muscle activity while walking with the exoskeleton. Synergies calculated with the exoskeleton demonstrated greater changes in synergy weights with increasing exoskeleton work versus greater changes in synergy activations with increasing exoskeleton torque. These results support the theory that unimpaired individuals do not exclusively use central pattern generators or other low-level building blocks to coordinate muscle activity, especially when learning a new task or adapting to external assistance, and demonstrate the potential for using exoskeletons to modulate muscle recruitment and coordination patterns for rehabilitation or performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Immediate effect of walking with talus-stabilizing taping on ankle kinematics in subjects with limited ankle dorsiflexion.

    Science.gov (United States)

    Kang, Min-Hyeok; Kim, Ji-Won; Choung, Sung-Dae; Park, Kyue-Nam; Kwon, Oh-Yun; Oh, Jae-Seop

    2014-08-01

    To determine the effects of walking with talus-stabilizing taping (TST) on ankle dorsiflexion (DF) and heel-off time in the stance phase of gait and ankle DF passive range of motion (PROM). Pre- and post-intervention study. University motion analysis laboratory. Ten subjects participated in this study. Sixteen ankles with limited ankle DF PROM were tested. Ankle DF PROM was measured using a goniometer, and maximum ankle DF before heel-off and time to heel-off in the stance phase of gait were measured using a 3D motion analysis system before and after walking with TST. Data were analyzed using a paired t-test. Ankle maximum DF before heel-off (p = 0.001), time to heel-off during the stance phase of gait (p = 0.005), and ankle DF PROM (p Walking with TST is an effective self-exercise for improving ankle kinematics during gait and increasing ankle DF PROM in individuals with limited ankle DF PROM. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. A multimodal approach to ankle instability: Interrelations between subjective and objective assessments of ankle status in athletes.

    Science.gov (United States)

    Golditz, Tobias; Welsch, Goetz H; Pachowsky, Milena; Hennig, Friedrich F; Pfeifer, Klaus; Steib, Simon

    2016-03-01

    The aim of this retrospective cohort study is to investigate the association between different subjective and objective assessments of ankle function in a population of athletes with or without functional ankle instability (FAI). 29 athletes with a history of ankle spraining were divided into two groups according to their ankle status: 16 with FAI (initial ankle sprain with residual functional instability) (age 24.6 ± 3.1 years), and 13 COPERS (initial ankle sprain without residual instability) (age 25.3 ± 4.4 years). The assessment of each individual's ankle function was based on three approaches: The "functional-ankle-ability-measure" (FAAM) assessing subjective ankle functionality, measures of sensorimotor control as objective functional measurements and MRI-based T2-mapping as a quantitative marker of compositional joint status. Pearson's product-moment-correlation coefficient, student's t-test and analysis-of-variance were used for statistical analysis. Significant group differences existed for subjective ankle function (FAAM, p = 0.04) and MRI-data mainly in the medial compartment of the ankle joint (p ≤ 0.05). We found unique associations between T2-mapping results and sensorimotor scores in the COPER (r = -0.756-0.849), and "FAI"-group (r = 0.630-0.657). The location and magnitude differed between groups. No correlations existed between these measures and the FAAM. This exploratory study provides preliminary evidence for potential interrelations between various diagnostic measures of ankle function and structure in individuals with and without FAI. We found associations between MRI-results and selected measures of sensorimotor control, indicating a potential link between loss of ankle function and early joint degeneration. Despite these interrelations, each of the different assessment options appears to contain unique information on ankle functionality important in a clinical assessment. © 2015 Orthopaedic Research Society. Published by Wiley

  17. Predicting functional recovery after acute ankle sprain.

    Directory of Open Access Journals (Sweden)

    Sean R O'Connor

    Full Text Available INTRODUCTION: Ankle sprains are among the most common acute musculoskeletal conditions presenting to primary care. Their clinical course is variable but there are limited recommendations on prognostic factors. Our primary aim was to identify clinical predictors of short and medium term functional recovery after ankle sprain. METHODS: A secondary analysis of data from adult participants (N = 85 with an acute ankle sprain, enrolled in a randomized controlled trial was undertaken. The predictive value of variables (age, BMI, gender, injury mechanism, previous injury, weight-bearing status, medial joint line pain, pain during weight-bearing dorsiflexion and lateral hop test recorded at baseline and at 4 weeks post injury were investigated for their prognostic ability. Recovery was determined from measures of subjective ankle function at short (4 weeks and medium term (4 months follow ups. Multivariate stepwise linear regression analyses were undertaken to evaluate the association between the aforementioned variables and functional recovery. RESULTS: Greater age, greater injury grade and weight-bearing status at baseline were associated with lower function at 4 weeks post injury (p<0.01; adjusted R square=0.34. Greater age, weight-bearing status at baseline and non-inversion injury mechanisms were associated with lower function at 4 months (p<0.01; adjusted R square=0.20. Pain on medial palpation and pain on dorsiflexion at 4 weeks were the most valuable prognostic indicators of function at 4 months (p< 0.01; adjusted R square=0.49. CONCLUSION: The results of the present study provide further evidence that ankle sprains have a variable clinical course. Age, injury grade, mechanism and weight-bearing status at baseline provide some prognostic information for short and medium term recovery. Clinical assessment variables at 4 weeks were the strongest predictors of recovery, explaining 50% of the variance in ankle function at 4 months. Further

  18. Assessment of the non-linear behaviour of plastic ankle foot orthoses by the finite element method.

    Science.gov (United States)

    Syngellakis, S; Arnold, M A; Rassoulian, H

    2000-01-01

    The stiffness characteristics of plastic ankle foot orthoses (AFOs) are studied through finite element modelling and stress analysis. Particular attention is given to the modelling and prediction of non-linear AFO behaviour, which has been frequently observed in previous experimental studies but not fully addressed analytically. Both large deformation effects and material non-linearity are included in the formulation and their individual influence on results assessed. The finite element program is subsequently applied to the simulation of a series of tests designed to investigate the relation between AFO trimline location and stiffness for moderate and large rotations. Through careful consideration and identification of key modelling parameters, the developed finite element solution proves to be a reliable and effective alternative means of assessing variations of a typical plastic AFO design so that particular patient requirements could be met, in the long term.

  19. Stiffness estimation of a parallel kinematic machine

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents a simple yet comprehensive approach to quickly estimating the stiff-ness of a tripod-based parallel kinematic machine. This approach can be implemented in two steps. Inthe first step, the machine structure is decomposed into two substructures associated with the machineframe and parallel mechanism. The stiffness models of these two substructures are formulated bymeans of virtual work principle. This is followed by the second step that enables the stiffness model ofthe machine structure as a whole to be achieved by linear superposition. The 3D representations of themachine stiffness within the usable workspace are depicted and the contributions of different componentrigidities to the machine stiffness are discussed. The result is compared with that obtained through finiteelement analysis.

  20. Measurement and Treatment of Passive Muscle Stiffness

    DEFF Research Database (Denmark)

    Kirk, Henrik

    This PhD thesis is based on research conducted at the University of Copenhagen and Helene Elsass Center from 2012 to 2015. Measurements and treatment of passive muscle stiffness in people with cerebral palsy (CP) comprise the focus of the thesis. The thesis summarizes the results from four studies......, which aimed to investigate: 1) The development of a clinical method to evaluate and distinguish neural (reflex mediated stiffness) and non-neural (passive muscle stiffness) components of muscle stiffness in adults with CP by objective and reliable measurements. 2) The association between increased...... passive muscle, muscle strength and gait function in adults with CP 3) The effect of resistance training and gait training accordingly on muscle strength, passive muscle stiffness and functional gait in adults with CP. The first part of the thesis defines reflex mediated stiffness and passive muscle...

  1. Numerical Analysis of Plastic Gear Stiffness

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    This paper established practical 3-D gear models to study the stiffness influencing factors of a loaded gear by finite element method, such as friction parameters, material properties, and gear structures. The research shows that, in elastic deformation, gear stiffness increases when sliding friction ability of contact pair decreases;meanwhile, the gear structure, especially asymmetric design in gear's shaft direction will also decrease gear stiffness.

  2. Ambulatory arterial stiffness index: rationale and methodology

    OpenAIRE

    Dolan, Eamon; Li,Yan; Thijs, Lutgarde; McCormack, Patricia; Staessen, Jan A; O'Brien, Eoin; Stanton, Alice

    2006-01-01

    OBJECTIVES: Increased arterial stiffness is associated with the development of cardiovascular disease and may even predict its development at an early stage. Increased pulse pressure is seen as a marker of increased arterial stiffness and can be readily measured by ambulatory blood pressure monitoring. We propose another surrogate measure of arterial stiffness derived from ambulatory blood pressure monitoring that may predict cardiovascular mortality over and above pulse pressure, namely, the...

  3. Diminished Foot and Ankle Muscle Volumes in Young Adults With Chronic Ankle Instability

    Science.gov (United States)

    Feger, Mark A.; Snell, Shannon; Handsfield, Geoffrey G.; Blemker, Silvia S.; Wombacher, Emily; Fry, Rachel; Hart, Joseph M.; Saliba, Susan A.; Park, Joseph S.; Hertel, Jay

    2016-01-01

    Background: Patients with chronic ankle instability (CAI) have demonstrated altered neuromuscular function and decreased muscle strength when compared with healthy counterparts without a history of ankle sprain. Up to this point, muscle volumes have not been analyzed in patients with CAI to determine whether deficits in muscle size are present following recurrent sprain. Purpose: To analyze intrinsic and extrinsic foot and ankle muscle volumes and 4-way ankle strength in young adults with and without CAI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Five patients with CAI (mean age, 23.0 ± 4 years; 1 male, 4 females) and 5 healthy controls (mean age, 23.8 ± 4.5 years; 1 male, 4 females) volunteered for this study. Novel fast-acquisition magnetic resonance imaging (MRI) was used to scan from above the femoral condyles through the foot and ankle. The perimeter of each muscle was outlined on each axial slice and then the 2-dimensional area was multiplied by the slice thickness (5 mm) to calculate the muscle volume. Plantar flexion, dorsiflexion, inversion, and eversion isometric strength were measured using a handheld dynamometer. Patients with CAI were compared with healthy controls on all measures of muscle volume and strength. Extrinsic muscle volumes of patients with CAI were also compared with a normative database of healthy controls (n = 24) by calculating z scores for each muscle individually for each CAI subject. Results: The CAI group had smaller total shank, superficial posterior compartment, soleus, adductor hallucis obliqus, and flexor hallucis brevis muscle volumes compared with healthy controls as indicated by group means and associated 90% CIs that did not overlap. Cohen d effect sizes for the significant group differences were all large and ranged from 1.46 to 3.52, with 90% CIs that did not cross zero. The CAI group had lower eversion, dorsiflexion, and 4-way composite ankle strength, all with group means and associated 90

  4. A new approach to determine press stiffness

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Wanheim, Tarras

    2004-01-01

    A new procedure is proposed for measuring press stiffness, including separated horizontal and vertical loading of the press frame. The load can be eccentrically positioned for measuring rotational stiffnesses. Two loading devices and corresponding measuring equipment for registration of press...... deflections are designed. The press stiffness is presented as a 6 by 6 flexibility matrix. The approach has been tested by measuring the stiffness of a 5000 kN O-frame, ring element, hydraulic press, a 10000 kN O-frame, pillar element, hydraulic press and a 10000 kN O-frame, ring element mechanical press...

  5. WAY TO DETERMINE STIFFNESS FUNCTION OF STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    WANG De-ming; GAI Bing-zheng

    2005-01-01

    For calculating the stiffness function of a structure, the differential equation of the vibration of the structure was divided into the differential equation on the original stiffness function that was known, and Fredholm integral equation of the first kind on the undetermined stiffness function that was unknown. And the stable solutions of the integral equation, when the smooth factor was equal to zero, was solved by the extrapolation with p smooth factors. So the stiffness function of the structure is obtained. Applied examples show that the method is feasible and effective.

  6. A Systematic Review on the Treatment of Acute Ankle Sprain Brace versus Other Functional Treatment Types

    NARCIS (Netherlands)

    E. Kemler; I. van de Port; F. Backx; C.N. van Dijk

    2011-01-01

    Ankle injuries, especially ankle sprains, are a common problem in sports and medical care. Ankle sprains result in pain and absenteeism from work and/or sports participation, and can lead to physical restrictions such as ankle instability. Nowadays, treatment of ankle injury basically consists of ta

  7. Combining dynamic stretch and tunable stiffness to probe cell mechanobiology in vitro.

    Directory of Open Access Journals (Sweden)

    Angela M Throm Quinlan

    Full Text Available Cells have the ability to actively sense their mechanical environment and respond to both substrate stiffness and stretch by altering their adhesion, proliferation, locomotion, morphology, and synthetic profile. In order to elucidate the interrelated effects of different mechanical stimuli on cell phenotype in vitro, we have developed a method for culturing mammalian cells in a two-dimensional environment at a wide range of combined levels of substrate stiffness and dynamic stretch. Polyacrylamide gels were covalently bonded to flexible silicone culture plates and coated with monomeric collagen for cell adhesion. Substrate stiffness was adjusted from relatively soft (G' = 0.3 kPa to stiff (G' = 50 kPa by altering the ratio of acrylamide to bis-acrylamide, and the silicone membranes were stretched over circular loading posts by applying vacuum pressure to impart near-uniform stretch, as confirmed by strain field analysis. As a demonstration of the system, porcine aortic valve interstitial cells (VIC and human mesenchymal stem cells (hMSC were plated on soft and stiff substrates either statically cultured or exposed to 10% equibiaxial or pure uniaxial stretch at 1 Hz for 6 hours. In all cases, cell attachment and cell viability were high. On soft substrates, VICs cultured statically exhibit a small rounded morphology, significantly smaller than on stiff substrates (p<0.05. Following equibiaxial cyclic stretch, VICs spread to the extent of cells cultured on stiff substrates, but did not reorient in response to uniaxial stretch to the extent of cells stretched on stiff substrates. hMSCs exhibited a less pronounced response than VICs, likely due to a lower stiffness threshold for spreading on static gels. These preliminary data demonstrate that inhibition of spreading due to a lack of matrix stiffness surrounding a cell may be overcome by externally applied stretch suggesting similar mechanotransduction mechanisms for sensing stiffness and

  8. Charcot foot and ankle with osteomyelitis

    OpenAIRE

    Donegan, Ryan; Sumpio, Bauer; Peter A. Blume

    2013-01-01

    This paper presents a review of the current literature discussing topics of Charcot osteoarthropathy, osteomyelitis, diagnosing osteomyelitis, antibiotic management of osteomyelitis, and treatment strategies for management of Charcot osteoarthropathy with concurrent osteomyelitis.Keywords: Charcot foot; osteomyelitis; diabetes mellitus; infection; neuropathy(Published: 1 October 2013)Citation: Diabetic Foot & Ankle 2013, 4: 21361 - http://dx.doi.org/10.3402/dfa.v4i0.21361

  9. [Ankle joint prosthesis for bone defects].

    Science.gov (United States)

    Lampert, C

    2011-11-01

    Large defects of the talus, i.e. due to tumors, large areas of osteolysis in total ankle replacement (TAR) and posttraumatic talus body necrosis are difficult to manage. The gold standard in these circumstances is still tibiocalcaneal arthrodesis with all the negative aspects of a completely rigid hindfoot. We started 10 years ago to replace the talus by a custom-made, all cobalt-chrome implant (laser sintering). The first patient with a giant cell tumor did very well but the following patients showed all subsidence of the metal talus into the tibia due to missing bony edges. Therefore, we constructed a custom-made talus (mirrored from the healthy side) and combined it with a well functioning total ankle prosthesis (Hintegra). So far we have implanted this custom-made implant into 3 patients: the first had a chondrosarcoma of the talus (1 year follow-up), the second had massive osteolysis/necrosis of unknown origin (6 months follow-up) and the third massive osteolysis following a correct TAR (2 months follow-up). The results are very encouraging as all of the patients are practically pain free and have a good range of movement (ROM): D-P flexion 15°-0-20° but less motion in the lower ankle joint: ROM P-S 5°-0-5°. No subsidence was detected in the tibia or the calcaneus. The custom-made talus combined with the Hintegra total ankle replacement will probably be an interesting alternative to a tibiocalcaneal arthrodesis in selected cases with massive defects of the talus.

  10. Symptomatic anterior subtalar arthrosis after ankle arthrodesis.

    Science.gov (United States)

    Lui, Tun Hing

    2014-05-13

    A 76-year-old man reported right lateral heel pain 11 years after ankle arthrodesis. Clinically, there was tenderness in the right sinus tarsi and over the junction point between the talonavicular and calcaneocuboid joints. Radiographs showed that the joint spaces of the posterior subtalar joint and the talonavicular joint were preserved although there were osteophytes at both joints. Arthroscopic findings showed degeneration of the anterior subtalar and talonavicular joints. The symptoms subsided after arthroscopic debridement. 2014 BMJ Publishing Group Ltd.

  11. Knee and ankle joint torque-angle relationships of multi-joint leg extension.

    Science.gov (United States)

    Hahn, Daniel; Olvermann, Matthias; Richtberg, Jan; Seiberl, Wolfgang; Schwirtz, Ansgar

    2011-07-28

    The force-length-relation (F-l-r) is an important property of skeletal muscle to characterise its function, whereas for in vivo human muscles, torque-angle relationships (T-a-r) represent the maximum muscular capacity as a function of joint angle. However, since in vivo force/torque-length data is only available for rotational single-joint movements the purpose of the present study was to identify torque-angle-relationships for multi-joint leg extension. Therefore, inverse dynamics served for calculation of ankle and knee joint torques of 18 male subjects when performing maximum voluntary isometric contractions in a seated leg press. Measurements in increments of 10° knee angle from 30° to 100° knee flexion resulted in eight discrete angle configurations of hip, knee and ankle joints. For the knee joint we found an ascending-descending T-a-r with a maximum torque of 289.5° ± 43.3 Nm, which closely matches literature data from rotational knee extension. In comparison to literature we observed a shift of optimum knee angle towards knee extension. In contrast, the T-a-r of the ankle joint vastly differed from relationships obtained for isolated plantar flexion. For the ankle T-a-r derived from multi-joint leg extension subjects operated over different sections of the force-length curve, but the ankle T-a-r derived from isolated joint efforts was over the ascending limb for all subjects. Moreover, mean maximum torque of 234.7 ± 56.6 Nm exceeded maximal strength of isolated plantar flexion (185.7 ± 27.8 Nm). From these findings we conclude that muscle function between isolated and more physiological multi-joint tasks differs. This should be considered for ergonomic and sports optimisation as well as for modelling and simulation of human movement.

  12. Reducing the metabolic cost of walking with an ankle exoskeleton: interaction between actuation timing and power.

    Science.gov (United States)

    Galle, Samuel; Malcolm, Philippe; Collins, Steven Hartley; De Clercq, Dirk

    2017-04-27

    Powered ankle-foot exoskeletons can reduce the metabolic cost of human walking to below normal levels, but optimal assistance properties remain unclear. The purpose of this study was to test the effects of different assistance timing and power characteristics in an experiment with a tethered ankle-foot exoskeleton. Ten healthy female subjects walked on a treadmill with bilateral ankle-foot exoskeletons in 10 different assistance conditions. Artificial pneumatic muscles assisted plantarflexion during ankle push-off using one of four actuation onset timings (36, 42, 48 and 54% of the stride) and three power levels (average positive exoskeleton power over a stride, summed for both legs, of 0.2, 0.4 and 0.5 W∙kg(-1)). We compared metabolic rate, kinematics and electromyography (EMG) between conditions. Optimal assistance was achieved with an onset of 42% stride and average power of 0.4 W∙kg(-1), leading to 21% reduction in metabolic cost compared to walking with the exoskeleton deactivated and 12% reduction compared to normal walking without the exoskeleton. With suboptimal timing or power, the exoskeleton still reduced metabolic cost, but substantially less so. The relationship between timing, power and metabolic rate was well-characterized by a two-dimensional quadratic function. The assistive mechanisms leading to these improvements included reducing muscular activity in the ankle plantarflexors and assisting leg swing initiation. These results emphasize the importance of optimizing exoskeleton actuation properties when assisting or augmenting human locomotion. Our optimal assistance onset timing and average power levels could be used for other exoskeletons to improve assistance and resulting benefits.

  13. Acute effect of stretching one leg on regional arterial stiffness in young men.

    Science.gov (United States)

    Yamato, Yosuke; Hasegawa, Natsuki; Fujie, Shumpei; Ogoh, Shigehiko; Iemitsu, Motoyuki

    2017-06-01

    Our previous study demonstrated that a single bout of stretching exercises acutely reduced arterial stiffness. We hypothesized that this acute vascular response is due to regional mechanical stimulation of the peripheral arteries. To test this hypothesis, we examined the effect of a single bout of passive one leg stretching on arterial stiffness, comparing the stretched and the non-stretched leg in the same subject. Twenty-five healthy young men (20.9 ± 0.3 years, 172.5 ± 1.4 cm, 64.1 ± 1.2 kg) volunteered for the study. Subjects underwent a passive calf stretching on one leg (six repetitions of 30-s static stretch with a 10-s recovery). Pulse wave velocity (PWV, an index of arterial stiffness), blood pressure (BP), and heart rate (HR) were measured before and immediately, 15, and 30 min after the stretching. Femoral-ankle PWV (faPWV) in the stretched leg was significantly decreased from baseline (835.0 ± 15.9 cm/s) to immediately (802.9 ± 16.8 cm/s, P stretching, despite no changes in systolic and diastolic BP, or HR. However, faPWV in the non-stretched leg was not significantly altered at any time. Brachial-ankle PWV (baPWV) also showed similar responses with faPWV, but this response was not significant. Additionally, the passive stretching did not alter carotid-femoral PWV (cfPWV). These results suggest that mechanical stimulation to peripheral arteries as induced by static passive stretch may modulate arterial wall properties directly, rather than resulting in a systemic effect.

  14. Forces predicted at the ankle during running.

    Science.gov (United States)

    Burdett, R G

    1982-01-01

    A biomechanical model of the ankle joint was developed and was used to predict the forces at the ankle during the stance phase of running. Measurements from five cadavers were averaged to obtain insertion points and directions of pull of equivalent tendons with respect to the assumed center of the ankle joint. A minimum joint force solution was obtained by assuming that only two equivalent muscle groups could exert force at one time. Three subjects ran at 4.47 m/s across a force platform that recorded the external forces and moments acting on the foot. Cinematography was used to measure the foot and leg positions during stance. Peak resultant joint forces ranging from 9.0 to 13.3 times body weight and peak Achilles tendon forces ranging from 5.3 to 10.0 times body weight were predicted. Small variations in some cases resulted in large differences in predicted forces. The highest tendon forces predicted exceeded those reported to cause damage to cadaver tendons in other studies.

  15. TO COMPARE THE EFFECTIVENESS OF CRYOTHERAPY WITH EXERCISES VERSUS TAPING WITH EXERCISES IN TREATING ACUTE LATERAL ANKLE SPRAIN

    Directory of Open Access Journals (Sweden)

    Suresh

    2014-12-01

    Full Text Available BACKGROUND: Ankle sprain is a common form of sport injuries and it is a leading cause of pain and disability in common man and sportsman worldwide. Rate of this injury is 1 per 10, 000 persons in common man whereas lateral ligament injuries account for 15 to 25% of all sports injuries. Lateral ankle sprains are one of the most common injuries sustained in sports and exercise activities. It is one of the most common soft tissue injury encountered in clinical practice. Complications such as prolonged ankle pain, a high recurrence rate, and chronic laxity underline the importance of careful diagnosis and treatment of ankle sprain. Physical therapy such as cryotherapy and taping technique are frequently used and have been cited that use of cryotherapy and taping technique have shown significant improvement in relieving pain and improving functional ability. OBJECTIVES: This study is intended to find and compare the effectiveness of Cryotherapy and exercises versus taping and exercises in acute lateral ankle sprain. DESIGN: A comparative study. SETTING: Kempegowda department of Orthopaedics and Rehabilitation unit-Kempegowda institute of physiotherapy. SUBJECTS: 40 patients (20 in each group. INTERVENTION: Forty males and female patients with lateral ankle sprain belonging to an age group of 15-35 years were selected for the study who fulfilled the inclusion and exclusion criteria and were divided into two groups. Group A was treated with Cryotherapy and exercises and group B was treated with taping and exercises with a frequency of 7 sittings for one week. Treatment outcomes were assessed using VAS, ROM, and LEFS for pain and functional ability. OUTCOME MEASURES: VAS to measure pain intensity, ROM for stiffness and Lower extremity functional scale for functional ability. RESULT: In comparison with VAS, ROM and LEFS, Group B shows significant improvement of all the parameters than Group A. INTERPRETATION & CONCLUSION: Study findings concluded that

  16. Proportional EMG control of ankle plantar flexion in a powered transtibial prosthesis.

    Science.gov (United States)

    Wang, Jing; Kannape, Oliver A; Herr, Hugh M

    2013-06-01

    The human calf muscle generates 80% of the mechanical work to walk throughout stance-phase, powered plantar flexion. Powered plantar flexion is not only important for walking energetics, but also to minimize the impact on the leading leg at heel-strike. For unilateral transtibial amputees, it has recently been shown that knee load on the leading, intact limb decreases as powered plantar flexion in the trailing prosthetic ankle increases. Not surprisingly, excessive loads on the leading, intact knee are believed to be causative of knee osteoarthritis, a leading secondary impairment in lower-extremity amputees. In this study, we hypothesize that a transtibial amputee can learn how to control a powered ankle-foot prosthesis using a volitional electromyographic (EMG) control to directly modulate ankle powered plantar flexion. We here present preliminary data, and find that an amputee participant is able to modulate toe-off angle, net ankle work and peak power across a broad range of walking speeds by volitionally modulating calf EMG activity. The modulation of these key gait parameters is shown to be comparable to the dynamical response of the same powered prosthesis controlled intrinsically (No EMG), suggesting that transtibial amputees can achieve an adequate level of powered plantar flexion controllability using direct volitional EMG control.

  17. Muscle contributions to center of mass excursion in ankle and hip strategies during forward body tilting.

    Science.gov (United States)

    Ogaya, Shinya; Okita, Yusuke; Fuchioka, Satoshi

    2016-10-03

    Humans employ two distinct strategies to maintain balance during standing: the ankle and hip strategies. People with a high fall risk tend to alter their motion patterns during forward body tilting from a hip to an ankle strategy. Improved knowledge regarding how muscles control the center of mass (COM) during balancing would facilitate clinical assessment. The present study aimed to investigate individual muscle contributions to COM motion during forward body tilting with both ankle and hip strategies in 16 healthy adults. While standing, participants were instructed to oscillate their bodies and touch anterior and posterior targets at 0.5Hz. The anterior target was positioned at the sternum height level in a HIGH and 5% lower in a LOW condition to induce ankle and hip strategies, respectively. The muscle tension force was calculated from measured angle data using a two-dimensional, muscle-driven forward simulation model. Muscle contributions to COM acceleration during forward body tilting were calculated via induced acceleration analysis. Long hamstrings were found to increase upward-contributing action and forward COM acceleration in the LOW condition during forward tilting. In contrast, the contribution of the soleus to backward COM acceleration was reduced. These results imply that the contribution of hamstrings to forward COM acceleration is disadvantageous to fore-aft COM control and balance recovery during forward body tilting.

  18. Talar Osteochondroma Fracture Presenting as Posterior Ankle Impingement.

    Science.gov (United States)

    Ercin, Ersin; Bilgili, Mustafa Gokhan; Gamsizkan, Mehmet; Avsar, Serdar

    2016-05-01

    Osteochondromas are the most common benign bone tumors. They are usually asymptomatic and found incidentally. When symptomatic, the symptoms are usually due to its location and size. Fracture of an osteochondroma presenting as posterior ankle impingement is a rare condition. We describe a 22-year-old man with solitary exostosis who presented with a posterior ankle mass and posterior ankle impingement with 2 years of follow-up. Surgical intervention was the treatment of choice in this patient, and histologic examination revealed a benign osteochondroma. Osteochondromas found in the posterior aspect of the talus can be complicated by fracture due to persistent motion of the ankle. Talar osteochondroma should be included in the differential diagnosis of posterior ankle impingement causes. Posterior talar osteochondromas, especially when a stalk is present, should be treated surgically before it is more complicated by a fracture and posterior ankle impingement.

  19. Shearwave Dispersion Ultrasonic Vibrometry (SDUV) for measuring prostate shear stiffness and viscosity – An in vitro pilot study

    OpenAIRE

    Mitri, F. G.; Urban, M.W.; Fatemi, M.; Greenleaf, J.F.

    2010-01-01

    This paper reports shear stiffness and viscosity “virtual biopsy” measurements of three excised non-cancerous human prostates using shearwave dispersion ultrasound vibrometry (SDUV) in vitro. Improved methods for prostate guided-biopsy are required to effectively guide needle biopsy to the suspected site. In addition, tissue stiffness measurement helps identifying a suspected site to perform biopsy because stiffness has been shown to correlate with pathology. More importantly, early detection...

  20. How crouch gait can dynamically induce stiff-knee gait.

    Science.gov (United States)

    van der Krogt, Marjolein M; Bregman, Daan J J; Wisse, Martijn; Doorenbosch, Caroline A M; Harlaar, Jaap; Collins, Steven H

    2010-04-01

    Children with cerebral palsy frequently experience foot dragging and tripping during walking due to a lack of adequate knee flexion in swing (stiff-knee gait). Stiff-knee gait is often accompanied by an overly flexed knee during stance (crouch gait). Studies on stiff-knee gait have mostly focused on excessive knee muscle activity during (pre)swing, but the passive dynamics of the limbs may also have an important effect. To examine the effects of a crouched posture on swing knee flexion, we developed a forward-dynamic model of human walking with a passive swing knee, capable of stable cyclic walking for a range of stance knee crouch angles. As crouch angle during stance was increased, the knee naturally flexed much less during swing, resulting in a 'stiff-knee' gait pattern and reduced foot clearance. Reduced swing knee flexion was primarily due to altered gravitational moments around the joints during initial swing. We also considered the effects of increased push-off strength and swing hip flexion torque, which both increased swing knee flexion, but the effect of crouch angle was dominant. These findings demonstrate that decreased knee flexion during swing can occur purely as the dynamical result of crouch, rather than from altered muscle function or pathoneurological control alone.

  1. Estrogen receptor-alpha genotype affects exercise-related reduction of arterial stiffness.

    Science.gov (United States)

    Hayashi, Koichiro; Maeda, Seiji; Iemitsu, Motoyuki; Otsuki, Takeshi; Sugawara, Jun; Tanabe, Takumi; Miyauchi, Takashi; Kuno, Shinya; Ajisaka, Ryuichi; Matsuda, Mitsuo

    2008-02-01

    Arterial stiffness, an independent risk factor for cardiovascular disease, increases with advancing age. Arterial stiffness is improved by regular exercise, but individual responses to exercise training are variable. Given that estrogen and estrogen receptor-alpha (ER-alpha) can induce vasodilation and can exert an antiatherosclerotic effect in vessels, we hypothesized that gene polymorphisms of ER-alpha might influence the ability of regular exercise to improve arterial stiffness in postmenopausal women. One hundred ninety-five healthy postmenopausal women (62 +/- 6 yr, mean +/- SD) participated in our cross-sectional study. We determined the genotype of single-nucleotide polymorphisms (SNP) at -401T/C of intron 1 of the ER-alpha gene. Arterial stiffness was measured by brachial-ankle pulse wave velocity (baPWV), and daily physical activity was estimated by a uniaxial accelerometer. Subjects were divided into active and inactive groups according to the median value (200 kcal.d(-1)) of energy expenditure. baPWV in individuals with the TT variant of -401T/C genotype were significantly higher than for individuals with the TC+CC genotype. No significant differences in mean baPWV values were found between the active group and the inactive group (P = 0.09). A significant reduction of baPWV secondary to increased daily physical activity was observed in individuals with the TC+CC genotype but not in individuals with the TT genotype (TT/active: 1470 +/- 36 cm.s(-1); TT/inactive: 1457 +/- 34 cm.s(-1); TC+CC/active: 1359 +/- 21 cm.s(-1); TC+CC/inactive: 1433 +/- 24 cm.s(-1)). These results suggest that ER-alpha polymorphism affects the regular exercise-related reduction in arterial stiffness in healthy postmenopausal women.

  2. Arterial stiffness, antiphospholipid antibodies, and pulmonary arterial hypertension in systemic lupus erythematosus.

    Science.gov (United States)

    Lee, Ji Hyun; Im Cho, Kyoung

    2014-12-01

    The aim of this study is to evaluate the role of arterial stiffness in pulmonary arterial hypertension (PAH) in systemic lupus erythematosus (SLE) patients and its relationship with antiphospholipid antibody (aPL). Measurement of brachial ankle pulse wave velocity (baPWV), carotid arterial stiffness, and pulmonary vascular resistance (PVR) was performed in 51 patients with SLE. PAH was diagnosed if the pulmonary artery systolic pressure was >40mmHg. Information concerning SLE duration, medication, and serum autoantibodies was recorded. SLE activity was assessed by the SLE disease activity index (SLEDAI). aPL was present in 10 patients (20%), and PAH was detected in 6 patients (12%). The prevalence of Raynaud's phenomenon, baPWV, positive aPL, and titers of IgG anticardiolipin antibody (aCL) were increased in SLE with PAH; however, no difference was found in inflammatory markers, disease duration, and SLEDAI compared to SLE without PAH. Carotid artery deformation and right ventricular function were reduced in patients with PAH (all p<0.05). Carotid artery circumferential strain (r=0.34, p=0.021), radial strain (r=-0.30, p=0.045), and baPWV (r=0.46, p=0.001) showed significant correlation between IgG aCL. Univariate and multiple regression analysis revealed that the only significant independent predictors of the presence of PAH were baPWV, carotid artery stiffness, and IgG aCL. Arterial stiffness might contribute to the pathogenesis of PAH related to SLE as well as aPLs. Furthermore, the significant association of aPL with arterial stiffness suggests its important role in PAH with SLE. Copyright © 2014 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  3. Design, modelling and simulation aspects of an ankle rehabilitation device

    Science.gov (United States)

    Racu, C. M.; Doroftei, I.

    2016-08-01

    Ankle injuries are amongst the most common injuries of the lower limb. Besides initial treatment, rehabilitation of the patients plays a crucial role for future activities and proper functionality of the foot. Traditionally, ankle injuries are rehabilitated via physiotherapy, using simple equipment like elastic bands and rollers, requiring intensive efforts of therapists and patients. Thus, the need of robotic devices emerges. In this paper, the design concept and some modelling and simulation aspects of a novel ankle rehabilitation device are presented.

  4. Assessment and management of patients with ankle injuries.

    Science.gov (United States)

    Walker, Jennie

    2014-08-19

    Foot and ankle injuries are common and can have a significant effect on an individual's daily activities. Nurses have an important role in the assessment, management, ongoing care and support of patients with ankle injuries. An understanding of the anatomy and physiology of the ankle enables nurses to identify significant injuries, which may result in serious complications, and communicate effectively with the multidisciplinary team to improve patient care and outcomes.

  5. The product of resting heart rate times blood pressure is associated with high brachial-ankle pulse wave velocity.

    Science.gov (United States)

    Wang, Anxin; Tao, Jie; Guo, Xiuhua; Liu, Xuemei; Luo, Yanxia; Liu, Xiurong; Huang, Zhe; Chen, Shuohua; Zhao, Xingquan; Jonas, Jost B; Wu, Shouling

    2014-01-01

    To investigate potential associations between resting heart rate, blood pressure and the product of both, and the brachial-ankle pulse wave velocity (baPWV) as a maker of arterial stiffness. The community-based "Asymptomatic Polyvascular Abnormalities in Community (APAC) Study" examined asymptomatic polyvascular abnormalities in a general Chinese population and included participants with an age of 40+ years without history of stroke and coronary heart disease. Arterial stiffness was defined as baPWV≥1400 cm/s. We measured and calculated the product of resting heart rate and systolic blood pressure (RHR-SBP) and the product of resting heart rate and mean arterial pressure (RHR-MAP). The study included 5153 participants with a mean age of 55.1 ± 11.8 years. Mean baPWV was 1586 ± 400 cm/s. Significant (Pheart rate or higher arterial blood pressure, with the highest baPWV observed in individuals from the highest quartiles of resting heart rate and blood pressure. After adjusting for confounding parameters such as age, sex, educational level, body mass index, fasting blood concentrations of glucose, blood lipids and high-sensitive C-reactive protein, smoking status and alcohol consumption, prevalence of arterial stiffness increased significantly (Pheart rate in combination with higher blood pressure are risk factors for arterial stiffness.

  6. Benign and malignant tumors of the foot and ankle

    Energy Technology Data Exchange (ETDEWEB)

    Singer, Adam D.; Datir, Abhijit; Langley, Travis [Emory University Hospital, Department of Radiology, Section of Musculoskeletal Imaging, Atlanta, GA (United States); Tresley, Jonathan [University of Wisconsin, Department of Radiology, Madison, WI (United States); Clifford, Paul D.; Jose, Jean; Subhawong, Ty K. [University of Miami, Department of Radiology, Miami, FL (United States)

    2016-03-15

    Pain and focal masses in the foot and ankle are frequently encountered and often initiate a workup including imaging. It is important to differentiate benign lesions from aggressive benign or malignant lesions. In this review, multiple examples of osseous and soft tissue tumors of the foot and ankle will be presented. Additionally, the compartmental anatomy of the foot and ankle will be discussed in terms of its relevance for percutaneous biopsy planning and eventual surgery. Finally, a general overview of the surgical management of benign, benign aggressive and malignant tumors of the foot and ankle will be discussed. (orig.)

  7. Joint mobilization acutely improves landing kinematics in chronic ankle instability.

    Science.gov (United States)

    Delahunt, Eamonn; Cusack, Kim; Wilson, Laura; Doherty, Cailbhe

    2013-03-01

    The objective of this study is to examine the acute effect of ankle joint mobilizations akin to those performed in everyday clinical practice on sagittal plane ankle joint kinematics during a single-leg drop landing in participants with chronic ankle instability (CAI). Fifteen participants with self-reported CAI (defined as mobilizations performed included Mulligan talocrural joint dorsiflexion mobilization with movement, Mulligan inferior tibiofibular joint mobilization, and Maitland anteroposterior talocrural joint mobilization. Three CODA cx1 units (Charnwood Dynamics Ltd., Leicestershire, UK) were used to provide information on ankle joint sagittal plane angular displacement. The dependent variable under investigation was the angle of ankle joint plantarflexion at the point of initial contact during the drop landing. There was a statistically significant acute decrease in the angle of ankle joint plantarflexion from premobilization (34.89° ± 4.18°) to postmobilization (31.90° ± 5.89°), t(14) = 2.62, P mobilization was 2.98° with a 95% confidence interval ranging from 0.54 to 5.43. The eta squared statistic (0.32) indicated a large effect size. These results indicate that mobilization acted to acutely reduce the angle of ankle joint plantarflexion at initial contact during a single-leg drop landing. Mobilization applied to participants with CAI has a mechanical effect on the ankle joint, thus facilitating a more favorable positioning of the ankle joint when landing from a jump.

  8. Subtalar Fusion Rate in Patients With Previous Ipsilateral Ankle Arthrodesis.

    Science.gov (United States)

    Zanolli, Diego H; Nunley, James A; Easley, Mark E

    2015-09-01

    Isolated subtalar arthrodesis is generally successful, with reported fusion rates of 84% to 100%. However, alteration of subtalar joint mechanics and talar body vasculature after ankle fusion may negatively influence subsequent ipsilateral subtalar joint fusion. Because there is very limited information on the subtalar fusion rate in patients with previous ipsilateral ankle fusion, the purpose of this study was to describe fusion rates in subtalar joint arthrodesis with and without preexisting ankle fusion in a large consecutive series of primary subtalar arthrodesis cases. All primary subtalar fusions performed between January 2000 and December 2010 were reviewed. Thirteen of 151 consecutive cases were in patients with existing ipsilateral ankle fusions. All patients were evaluated for clinical and radiographic evidence of nonunion at follow-up, and fusion rates in the groups with and without previous ipsilateral ankle fusion were compared. Five nonunions occurred in the 13 cases with prior ipsilateral ankle arthrodesis, a 61.5% fusion rate. Twelve nonunions were identified in the 138 cases without prior ankle arthrodesis, a significantly higher fusion rate of 91.3% (P = .007). In our series, the subtalar fusion rate in patients with previous ipsilateral ankle arthrodesis was significantly lower than that for subtalar arthrodesis in the absence of ipsilateral ankle arthrodesis. Level III, retrospective comparative study. © The Author(s) 2015.

  9. Pioglitazone improves the cardio-ankle vascular index in patients with type 2 diabetes mellitus treated with metformin

    Directory of Open Access Journals (Sweden)

    Ohira M

    2014-07-01

    Full Text Available Masahiro Ohira,1 Takashi Yamaguchi,1 Atsuhito Saiki,1 Noriko Ban,1 Hidetoshi Kawana,1 Ayako Nagumo,1 Takeyoshi Murano,2 Kohji Shirai,3 Ichiro Tatsuno1 1Center for Diabetes, Endocrinology and Metabolism, 2Department of Clinical Laboratory Medicine, 3Department of Vascular Function, Sakura Hospital, Toho University Medical Center, Chiba, Japan Background: Type 2 diabetes is known to be associated with elevated cardiovascular mortality. Pioglitazone improves blood pressure (BP and pulse wave velocity (PWV, which is an arterial stiffness parameter. Arterial stiffness is closely associated with cardiovascular disease. However, PWV is correlated with BP. The cardio-ankle vascular index (CAVI reflects arterial stiffness independent of BP. Pioglitazone improves PWV but reduces blood pressure. The aim of this study was to re-evaluate the effect of pioglitazone on arterial stiffness with CAVI. Methods: Sixty patients with type 2 diabetes mellitus and already on 500 mg/day of metformin received add-on therapy of pioglitazone 15 mg/day or glimepiride 1 mg/day for 6 months, during which time changes in their metabolic parameters and CAVI were observed. Results: After 6 months of treatment, both pioglitazone (n=30 and glimepiride (n=30 improved fasting blood glucose and glycated hemoglobin. The changes in fasting blood glucose and glycated hemoglobin between the two groups were greater in the pioglitazone group. Systolic and diastolic BP was decreased in both groups, with no significant between-group differences. Only pioglitazone increased serum adiponectin levels, and the change in adiponectin between the pioglitazone and glimepiride groups was significantly different. CAVI was decreased significantly by pioglitazone but remained unchanged after treatment with glimepiride. The change in CAVI between the two groups was significantly different. Conclusion: These results suggest that pioglitazone improves CAVI, a BP-independent arterial stiffness parameter

  10. Stiff person syndrome: a case report.

    Science.gov (United States)

    Kelly, Patricia A; Kuberski, Carolyn

    2014-08-01

    The case report features a patient who had a diagnosis of a common type of breast cancer with an uncommon neurologic syndrome. She had extreme pain and progressive stiffness with cognitive and functional decline. This article includes the pathogenesis and treatment options for a rare, but treatable, autoimmune disorder of malignancy called stiff person syndrome.

  11. Arterial Stiffness and Dialysis Calcium Concentration

    Directory of Open Access Journals (Sweden)

    Fabrice Mac-Way

    2011-01-01

    Full Text Available Arterial stiffness is the major determinant of isolated systolic hypertension and increased pulse pressure. Aortic stiffness is also associated with increased cardiovascular morbidity and mortality in patients with chronic kidney disease, hypertension, and general population. Hemodynamically, arterial stiffness results in earlier aortic pulse wave reflection leading to increased cardiac workload and decreased myocardial perfusion. Although the clinical consequence of aortic stiffness has been clearly established, its pathophysiology in various clinical conditions still remains poorly understood. The aim of the present paper is to review the studies that have looked at the impact of dialysis calcium concentration on arterial stiffness. Overall, the results of small short-term studies suggest that higher dialysis calcium is associated with a transient but significant increase in arterial stiffness. This calcium dependant increase in arterial stiffness is potentially explained by increased vascular smooth muscle tone of the conduit arteries and is not solely explained by changes in mean blood pressure. However, the optimal DCa remains to be determined, and long term studies are required to evaluate its impact on the progression of arterial stiffness.

  12. Determination of 6 stiffnesses for a press

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Eriksen, Morten; Wanheim, Tarras

    2000-01-01

    the workpiece will result in deflections of the press, which will decrease the tolerances of the component. At present, it is possible to measure the reaction forces from the workpiece, for instance by use of the model material technique as described in [1-2]. If the stiffness and clearances of the press...... is known too, the final dimensions can be predicted by divide the force by the stiffness and add the clearance. If the stiffness of the press is known, it is possible to optimize the orientation of the workpiece too, so the direction, in which the best tolerances is demanded, is equal to the direction...... in which the press has the highest stiffness. Furthermore, knowledge about the stiffnesses of all presses in a production system makes it possible to choose the press which best fit to a specific process....

  13. Measurement and Treatment of Passive Muscle Stiffness

    DEFF Research Database (Denmark)

    Kirk, Henrik

    2016-01-01

    This PhD thesis is based on research conducted at the University of Copenhagen and Helene Elsass Center from 2012 to 2015. Measurements and treatment of passive muscle stiffness in people with cerebral palsy (CP) comprise the focus of the thesis. The thesis summarizes the results from four studies......, which aimed to investigate: 1) The development of a clinical method to evaluate and distinguish neural (reflex mediated stiffness) and non-neural (passive muscle stiffness) components of muscle stiffness in adults with CP by objective and reliable measurements 2) The association between increased......, and good correlation to measurements from a stationary dynamometer. The second part of the thesis discusses the finding of a significant correlation between gait function, reduced rate of force development (RFD), and increased passive muscle stiffness in adults with CP. Previously, the reflex...

  14. Rolling Element Bearing Stiffness Matrix Determination (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Y.; Parker, R.

    2014-01-01

    Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between bearing radial, axial, and tilting bearing deflections.

  15. Stiffness Control of Surgical Continuum Manipulators

    Science.gov (United States)

    Mahvash, Mohsen; Dupont, Pierre E.

    2013-01-01

    This paper introduces the first stiffness controller for continuum robots. The control law is based on an accurate approximation of a continuum robot’s coupled kinematic and static force model. To implement a desired tip stiffness, the controller drives the actuators to positions corresponding to a deflected robot configuration that produces the required tip force for the measured tip position. This approach provides several important advantages. First, it enables the use of robot deflection sensing as a means to both sense and control tip forces. Second, it enables stiffness control to be implemented by modification of existing continuum robot position controllers. The proposed controller is demonstrated experimentally in the context of a concentric tube robot. Results show that the stiffness controller achieves the desired stiffness in steady state, provides good dynamic performance, and exhibits stability during contact transitions. PMID:24273466

  16. Comparison of total ankle replacement and ankle arthrodesis in patients with haemophilia using gait analysis: two case reports

    OpenAIRE

    Dauty, Marc; Gross, Raphael; Leboeuf, Fabien; Trossaert, Marc

    2015-01-01

    Background Severe hemophilia is an inherited, lifelong bleeding disorder characterized by spontaneous bleeding, which results in painful joint deformities. Currently two surgical treatments are available to treat haemophilia-related ankle joint destruction: ankle arthrodesis and total ankle replacement. The aim of the present study was to compare these two surgical procedures in haemophiliac subjects. Case presentation Kinematic and dynamic parameters were quantified using a three-dimensional...

  17. Is End-Stage Ankle Arthrosis Best Managed with Total Ankle Replacement or Arthrodesis? A Systematic Review

    OpenAIRE

    Jordan, Robert W.; Chahal, Gurdip S.; Anna Chapman

    2014-01-01

    Introduction. End-stage ankle osteoarthritis is a debilitating condition. Traditionally, ankle arthrodesis (AA) has been the surgical intervention of choice but the emergence of total ankle replacement (TAR) has challenged this concept. This systematic review aims to address whether TAR or AA is optimal in terms of functional outcomes. Methods. We conducted a systematic review according to PRISMA checklist using the online databases Medline and EMBASE after January 1, 2005. Participants must ...

  18. Adaptive control of a variable-impedance ankle-foot orthosis to assist drop-foot gait.

    Science.gov (United States)

    Blaya, Joaquin A; Herr, Hugh

    2004-03-01

    An active ankle-foot orthoses (AAFO) is presented where the impedance of the orthotic joint is modulated throughout the walking cycle to treat drop-foot gait. During controlled plantar flexion, a biomimetic torsional spring control is applied where orthotic joint stiffness is actively adjusted to minimize forefoot collisions with the ground. Throughout late stance, joint impedance is minimized so as not to impede powered plantar flexion movements, and during the swing phase, a torsional spring-damper control lifts the foot to provide toe clearance. To assess the clinical effects of variable-impedance control, kinetic and kinematic gait data were collected on two drop-foot participants wearing the AAFO. For each participant, zero, constant, and variable impedance control strategies were evaluated and the results were compared to the mechanics of three age, weight, and height matched normals. We find that actively adjusting joint impedance reduces the occurrence of slap foot allows greater powered plantar flexion and provides for less kinematic difference during swing when compared to normals. These results indicate that a variable-impedance orthosis may have certain clinical benefits for the treatment of drop-foot gait compared to conventional ankle-foot orthoses having zero or constant stiffness joint behaviors.

  19. Association of inflammatory gene polymorphisms and conventional risk factors with arterial stiffness by age.

    Science.gov (United States)

    Kheradmand, Motahare; Niimura, Hideshi; Kuwabara, Kazuyo; Nakahata, Noriko; Nakamura, Akihiko; Ogawa, Shin; Mantjoro, Eva Mariane; Shimatani, Keiichi; Nerome, Yasuhito; Owaki, Tetsuhiro; Kusano, Ken; Takezaki, Toshiro

    2013-01-01

    Inflammatory gene polymorphisms are potentially associated with atherosclerosis risk, but their age-related effects are unclear. To investigate the age-related effects of inflammatory gene polymorphisms on arterial stiffness, we conducted cross-sectional and 5-year follow-up studies using the cardio-ankle vascular index (CAVI) as a surrogate marker of arterial stiffness. We recruited 1850 adults aged 34 to 69 years from the Japanese general population. Inflammatory gene polymorphisms were selected from NF-kB1, CD14, IL-6, IL-10, MCP-1, ICAM-1, and TNF-α. Associations of CAVI with genetic and conventional risk factors were estimated by sex and age group (34-49, 50-59, and 60-69 years) using a general linear model. The association with 5-year change in CAVI was examined longitudinally. Glucose intolerance was associated with high CAVI among women in all age groups, while hypertension was associated with high CAVI among participants in all age groups, except younger women. Mean CAVI for the CD14 CC genotype was lower than those for the TT and CT genotypes (P for trend = 0.005), while the CD14 polymorphism was associated with CAVI only among men aged 34 to 49 years (P = 0.006). No association of the other 6 polymorphisms with CAVI was observed. No association with 5-year change in CAVI was apparent. Inflammatory gene polymorphisms were not associated with arterial stiffness. To confirm these results, further large-scale prospective studies are warranted.

  20. Impact attenuation properties of jazz shoes alter lower limb joint stiffness during jump landings.

    Science.gov (United States)

    Fong Yan, Alycia; Smith, Richard M; Hiller, Claire E; Sinclair, Peter J

    2017-05-01

    To quantify the impact attenuation properties of the jazz shoes, and to investigate the in-vivo effect of four jazz shoe designs on lower limb joint stiffness during a dance-specific jump. Repeated measures. A custom-built mechanical shoe tester similar to that used by athletic shoe companies was used to vertically impact the forefoot and heel region of four different jazz shoe designs. Additionally, dancers performed eight sautés in second position in bare feet and the shoe conditions. Force platforms and 3D-motion capture were used to analyse the joint stiffness of the midfoot, ankle, knee and hip during the jump landings. Mechanical testing of the jazz shoes revealed significant differences in impact attenuation characteristics among each of the jazz shoe designs. Gross knee and midfoot joint stiffness were significantly affected by the jazz shoe designs in the dancers' jump landings. The tested jazz shoe designs altered the impact attenuating capacity of jump landing technique in dancers. The cushioned jazz shoes are recommended particularly for injured dancers to reduce impact on the lower limb. Jazz shoe design should consider the impact attenuation properties of the forefoot region, due to the toe-strike landing technique in dance movement. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  1. Association between arterial stiffness and left ventricular diastolic function in relation to gender and age

    Science.gov (United States)

    Kim, Hack-Lyoung; Lim, Woo-Hyun; Seo, Jae-Bin; Chung, Woo-Young; Kim, Sang-Hyun; Kim, Myung-A.; Zo, Joo-Hee

    2017-01-01

    Abstract Left ventricular (LV) diastolic dysfunction and subsequent overt heart failure are more prevalent in elderly women. Close interaction between arterial stiffness and LV morphology/function has been reported. The aim of this study was to investigate whether there is an age- and gender-dependent relationship between arterial stiffness and LV diastolic function. A total of 819 subjects (58.6 ± 13.3 years, 50.2% men) without structural heart disease (LV ejection fraction ≥50%) were retrospectively analyzed. All participants underwent transthoracic echocardiography and brachial-ankle pulse wave velocity (baPWV) measurement on the same day. The association of baPWV with septal e′ velocity and average E/e′ was assessed. In the total study subjects, baPWV was negatively correlated with septal e′ velocity (r = 0.383, P  0.05 for each). In conclusion, baPWV was independently associated with septal e′ velocity and E/e′ in elderly women but not in younger women or men. The results of this study provide additional evidence that increased arterial stiffness plays an important role in the development of heart failure with preserved ejection fraction as well as LV diastolic dysfunction in elderly women. PMID:28072727

  2. Acute decrease in the stiffness of resting muscle belly due to static stretching.

    Science.gov (United States)

    Taniguchi, K; Shinohara, M; Nozaki, S; Katayose, M

    2015-02-01

    The purpose of the study was to examine the acute effect of static stretching exercise on the resting stiffness of gastrocnemius muscle belly. Ten healthy young adults performed standing wall stretching in dorsiflexion for 1 min at a time and repeated five times. Before and after stretching, the shear modulus was measured in medial and lateral heads of the resting gastrocnemius muscle with ultrasound shear-wave elastography. After the stretching, dorsiflexion range of motion (ROM) of the ankle joint increased (P stretching, shear modulus decreased (P stretching across muscle heads. The decrease in shear modulus returned in 20 min after stretching. In the comparison group of 10 additional subjects, the standing intervention without stretching had no influence on these measures. There was a negative correlation between dorsiflexion ROM and shear modulus in either head before and after stretching. The results demonstrate the transient decreases in the stiffness of the resting gastrocnemius muscle belly and indicate that joint flexibility is greater in individuals with lower resting stiffness of the muscle belly.

  3. Serum ferritin levels are associated with arterial stiffness in healthy Korean adults.

    Science.gov (United States)

    Ha, Ji Yoon; Kim, Min Kyung; Kang, Shinae; Nam, Ji Sun; Ahn, Chul Woo; Kim, Kyung Rae; Park, Jong Suk

    2016-08-01

    Although an association between serum ferritin and atherosclerosis has been suggested, limited epidemiologic data are available regarding the association between ferritin and arterial stiffness in healthy adults. A total of 2932 healthy subjects were enrolled in this study. Anthropometric and biochemical profiles including ferritin were measured. The arterial stiffness was measured using brachial-ankle pulse wave velocity (baPWV). Serum ferritin levels were classified into quartiles and baPWV values gradually increased with each ferritin quartile. Multiple regression analysis showed that ferritin levels were independently correlated with baPWV. After adjusting for multiple risk factors, as compared with the lowest quartile, the odds ratios for high baPWV (>75(th) percentile) were 1.15 (0.84-1.56), 1.37 (0.97-1.73), and 1.46 (1.29-2.17) among men (p for trend ferritin, respectively. In conclusion, serum ferritin levels are independently associated with arterial stiffness in healthy Korean adults. © The Author(s) 2016.

  4. Evaluation of a smartphone-based assessment system in subjects with chronic ankle instability.

    Science.gov (United States)

    Chiu, Ya-Lan; Tsai, Yi-Ju; Lin, Chueh-Ho; Hou, You-Ruei; Sung, Wen-Hsu

    2017-02-01

    Ankle sprain is the most common sports-related injury, and approximately 80% of patients studied suffered recurrent sprains. These repeated ankle injuries could cause chronic ankle instability, a decrease in sports performance, and a decrease in postural control ability. At the present time, smartphones have become very popular and powerful devices, and smartphone applications (apps) that have been shown to have good validity have been designed to measure human body motion. However, the app focusing on ankle function assessment and rehabilitation is still not widely used and has very limited functions. The purpose of this study is to evaluate the feasibility of smartphone-based systems in the assessment of postural control ability for patients with chronic ankle instability. Fifteen physically active adults (6 male, 9 female; aged = 23.4 ± 5.28 years; height = 167.13 ± 7.3 cm; weight = 62.06 ± 10.82 kg; BMI = 22.08 ± 2.57 kg/ m(2)) were recruited, and these participants had at least one leg that was evaluated as scoring lower than 27 points according to the Cumberland Ankle Instability Tool (CAIT). The smartphone used in the study was ASUS Zenfone 2, and an app developed using MIT App Inventor was used to record built-in accelerometer data during the assessment process. Subjects were asked to perform single leg stance for 20 s in eyes-open and eyes-closed conditions with each leg. The smartphone was fixed in an upright position on the middle of the shin, using an exercise armband, with the screen facing forward. The average of recorded acceleration data was used to represent the postural control performance, and higher values indicated more instability. Data were analyzed with a paired t-test with SPSS 17.0, and the statistical significance was set as alpha smartphone software can be used to discriminate between the different performances of the healthier leg and injured leg, and also between eyes-open and eyes

  5. Finite element analysis of a total ankle replacement during the stance phase of gait.

    Science.gov (United States)

    Reggiani, B; Leardini, A; Corazza, F; Taylor, M

    2006-01-01

    Total ankle replacement (TAR) designs have still several important issues to be addressed before the treatment becomes fully acceptable clinically. Very little is known about the performance, in terms of the contact pressures and kinematics of TAR when subjected to daily activities such as level gait. For this purpose, an explicit finite element model of a novel 3-component TAR was developed, which incorporated a previously validated mechanical model of the ankle ligament apparatus. The intermediate mobile polyethylene meniscal bearing was modelled as an elastic-plastic continuum while the articulating surfaces of the tibial and talar metal components as rigid bodies. Overall kinematics, contact pressures and ligament forces were analysed during passive, i.e. virtually unloaded, and active, i.e. stance phase of gait, conditions. Simulation of passive motion predicted similar kinematics as reported previously in an analytical four-bar linkage model. The meniscal bearing was observed to move 5.6 mm posteriorly during the simulated stance and the corresponding antero-posterior displacement of the talar component was 8.3 mm. The predicted pattern and the amount (10.6 degrees ) of internal-external rotation of the ankle complex were found to be in good agreement with corresponding in vivo measurements on normal ankles. A peak contact pressure of 16.8 MPa was observed, with majority of contact pressures below 10 MPa. For most ligaments, reaction forces remain within corresponding physiological ranges. A first realistic representation of the biomechanical behaviour of the human ankle when replaced by prosthetic joints is provided. The applied methodology can potentially be applied to other TAR designs.

  6. Proportional EMG control of ankle plantar flexion in a powered transtibial prosthesis.

    OpenAIRE

    Wang, Jing; Kannape, Oliver; Herr, Hugh M.

    2013-01-01

    The human calf muscle generates 80% of the mechanical work to walk throughout stance-phase, powered plantar flexion. Powered plantar flexion is not only important for walking energetics, but also to minimize the impact on the leading leg at heel-strike. For unilateral transtibial amputees, it has recently been shown that knee load on the leading, intact limb decreases as powered plantar flexion in the trailing prosthetic ankle increases. Not surprisingly, excessive loads on the leading, intac...

  7. Design and experimental evaluation of a lightweight, high-torque and compliant actuator for an active ankle foot orthosis.

    Science.gov (United States)

    Moltedo, Marta; Bacek, Tomislav; Langlois, Kevin; Junius, Karen; Vanderborght, Bram; Lefeber, Dirk

    2017-07-01

    The human ankle joint plays a crucial role during walking. At the push-off phase the ankle plantarflexors generate the highest torque among the lower limb joints during this activity. The potential of the ankle plantarflexors is affected by numerous pathologies and injuries, which cause a decrease in the ability of the subject to achieve a natural gait pattern. Active orthoses have shown to have potential in assisting these subjects. The design of such robots is very challenging due to the contrasting design requirements of wearability (light weight and compact) and high torques capacity. This paper presents the development of a high-torque ankle actuator to assist the ankle joint in both dorsiflexion and plantarflexion. The compliant actuator is a spindle-driven MACCEPA (Mechanically Adjustable Compliance and Controllable Equilibrium Position Actuator). The design of the actuator was made to keep its weight as low as possible, while being able to provide high torques. As a result of this novel design, the actuator weighs 1.18kg. Some static characterization tests were perfomed on the actuator and their results are shown in the paper.

  8. Genetic determinants of arterial stiffness: Results from the Rotterdam Study

    NARCIS (Netherlands)

    M.P.S. Sie (Mark)

    2007-01-01

    textabstractArterial stiffness increases with age. It is also associated with various diseases, such as diabetes mellitus and hypertension. Recently, arterial stiffness has also been found to independently predict cardiovascular disease. The pathogenesis of arterial stiffness, however, has n

  9. Clinical measurement of mechanical ankle instability.

    Science.gov (United States)

    Parasher, Raju K; Nagy, Dawn R; Em, April L; Phillips, Howard J; Mc Donough, Andrew L

    2012-10-01

    Clinicians commonly use the anterior draw test (ligament laxity) and distal fibular position (lateral malleolus displacement), to measure ankle instability. The purpose of this study was to establish intra-rater and inter-rater reliability for the anterior draw test and distal fibular position in a clinical setting. The anterior draw test (AD) was measured with a plastic Goniometer, and was defined as the linear displacement of the foot as it is drawn anteriorly with the ankle held in 20 degrees of plantar-flexion. Distal fibular position (DFP) was measured in standing using a digital vernier caliper and was the relative linear distance between the lateral and the medial malleoli. 20 participants aged 21-28 volunteered for the study and were measured on both ankles. It was found that Intra-tester reliability (ICC) ranged from 0.88 to 0.97 for AD and DFP; while inter-tester reliability (ICC) was 0.6 for AD and 0.77 for DFP. In addition for measures across trials, the standard error of the measurement (SEM) was, on average 0.66 mm for AD and 1.7 mm for DFP. While the limits of agreement (LOA) was ±0.17 mm for AD and ±4.03 mm for DFP. However, the SEM and LOA between testers was 2.27 mm and ±2.27 mm respectively for AD; and for 3.1 mm and ±10.4 mm for DFP. Overall the results suggest that both measures, as defined in this study exhibit moderate to good reliability and low standard error of measurement, suggesting a high degree of repeatability across trials.

  10. Total ankle prostheses in rheumatoid arthropathy

    Science.gov (United States)

    Schutte, Bernard; Louwerens, Jan Willem K; van den Hoogen, Frank H J; de Waal Malefijt, Maarten C

    2009-01-01

    Background and purpose The first generations of total ankle replacements (TARs) showed a high rate of early failure. In the last decades, much progress has been made in the development of TARs, with the newer generation showing better results. We evaluated TARs implanted with rheumatoid arthritis (RA) or juvenile inflammatory arthritis (JIA) as indication. Patients and methods 58 total ankle prostheses (Buechel-Pappas and STAR type) were implanted in patients with RA (n = 53) or JIA (n = 5) in 54 patients (4 bilateral). After a mean follow-up of 2.7 (1–9) years, all patients were reviewed by two orthopedic surgeons who were not the surgeons who performed the operation. Standard AP and lateral radiographs were taken and a Kofoed ankle score was obtained; this is a clinical score ranging from 0–100 and consists of sub-scores for pain, disability, and range of motion. Results 2 patients died of unrelated causes. Of the 52 patients who were alive (56 prostheses), 51 implants were still in place and showed no signs of loosening on the most recent radiographs. The mean Kofoed score at follow-up was 73 points (SD 16, range 21–92). 4 patients showed a poor result (score < 50) with persistent pain for which no obvious reason could be found. 5 implants were removed, 4 because of infection and 1 because of aseptic loosening. Interpretation Medium-term results of the STAR and BP types of TAR in RA were satisfactory. The main reason for failure of the implant was infection. PMID:19634020

  11. 10-year survival of total ankle arthroplasties

    Science.gov (United States)

    2011-01-01

    Background and purpose There is an ongoing need to review large series of total ankle replacements (TARs) for monitoring of changes in practice and their outcome. 4 national registries, including the Swedish Ankle Register, have previously reported their 5-year results. We now present an extended series with a longer follow-up, and with a 10-year survival analysis. Patients and methods Records of uncemented 3-component TARs were retrospectively reviewed, determining risk factors such as age, sex, and diagnosis. Prosthetic survival rates were calculated with exchange or removal of components as endpoint—excluding incidental exchange of the polyethylene meniscus. Results Of the 780 prostheses implanted since 1993, 168 (22%) had been revised by June 15, 2010. The overall survival rate fell from 0.81 (95% CI: 0.79–0.83) at 5 years to 0.69 (95% CI: 0.67–0.71) at 10 years. The survival rate was higher, although not statistically significantly so, during the latter part of the period investigated. Excluding the STAR prosthesis, the survival rate for all the remaining designs was 0.78 at 10 years. Women below the age of 60 with osteoarthritis were at a higher risk of revision, but age did not influence the outcome in men or women with rheumatoid arthritis. Revisions due to technical mistakes at the index surgery and instability were undertaken earlier than revisions for other reasons. Interpretation The results have slowly improved during the 18-year period investigated. However, we do not believe that the survival rates of ankle replacements in the near future will approach those of hip and knee replacements—even though improved instrumentation and design of the prostheses, together with better patient selection, will presumably give better results. PMID:22066551

  12. Tendinopathies of the foot and ankle.

    Science.gov (United States)

    Simpson, Michael R; Howard, Thomas M

    2009-11-15

    Because our understanding of tendinopathy has evolved in recent years, the condition is now considered a degenerative process; this affects the approach to treatment. Initial therapy should always involve relative rest and modification of physical activity, use of rehabilitative exercises, and evaluation of intrinsic and extrinsic causes of injury. The posterior tibial tendon is a dynamic arch stabilizer; injury to this tendon can cause a painful flat-footed deformity with hindfoot valgus and midfoot abduction (characterized by the too many toes sign). Treatment of posterior tibial tendinopathy is determined by its severity and can include immobilization, orthotics, physical therapy, or subspecialty referral. Because peroneal tendinopathy is often misdiagnosed, it can lead to chronic lateral ankle pain and instability and should be suspected in a patient with either of these symptoms. Treatment involves physical therapy and close monitoring for surgical indications. Achilles tendinopathy is often caused by overtraining, use of inappropriate training surfaces, and poor flexibility. It is characterized by pain in the Achilles tendon 4 to 6 cm above the point of insertion into the calcaneus. Evidence from clinical trials shows that eccentric strengthening of the calf muscle can help patients with Achilles tendinopathy. Flexor hallucis longus tendinopathy is most common among ballet dancers. Patients may complain of an insidious onset of pain in the posteromedial aspect of the ankle; treatment involves correcting physical training errors, focusing on body mechanics, and strengthening the body's core. Anterior tibial tendinopathy is rare, but is typically seen in patients older than 45 years. It causes weakness in dorsiflexion of the ankle; treatment involves short-term immobilization and physical therapy.

  13. Walking cycle control for an active ankle prosthesis with one degree of freedom monitored from a personal computer.

    Science.gov (United States)

    Cordero Andrés, Guzhñay; Arévalo Luis, Calle; Abad Julio, Zambrano

    2015-08-01

    This paper proposes a fuzzy control algorithm for human walking cycle of an active ankle prosthesis for people who have suffered amputation of the lower limb, the system has one degree of freedom in the sagittal plane. Also, a biomechanical analysis of foot and ankle is shown to define the phases of plantar support and swinging. The used actuator is an intelligent servomotor, Dynamixel MX-106T which has torque, current and position feedback, among others, allowing real-time telemetry of the prototype implemented in a microcontroller system.

  14. Robotic Ankle for Omnidirectional Rock Anchors

    Science.gov (United States)

    Parness, Aaron; Frost, Matthew; Thatte, Nitish

    2013-01-01

    Future robotic exploration of near-Earth asteroids and the vertical and inverted rock walls of lava caves and cliff faces on Mars and other planetary bodies would require a method of gripping their rocky surfaces to allow mobility without gravitational assistance. In order to successfully navigate this terrain and drill for samples, the grippers must be able to produce anchoring forces in excess of 100 N. Additionally, the grippers must be able to support the inertial forces of a moving robot, as well gravitational forces for demonstrations on Earth. One possible solution would be to use microspine arrays to anchor to rock surfaces and provide the necessary load-bearing abilities for robotic exploration of asteroids. Microspine arrays comprise dozens of small steel hooks supported on individual suspensions. When these arrays are dragged along a rock surface, the steel hooks engage with asperities and holes on the surface. The suspensions allow for individual hooks to engage with asperities while the remaining hooks continue to drag along the surface. This ensures that the maximum possible number of hooks engage with the surface, thereby increasing the load-bearing abilities of the gripper. Using the microspine array grippers described above as the end-effectors of a robot would allow it to traverse terrain previously unreachable by traditional wheeled robots. Furthermore, microspine-gripping robots that can perch on cliffs or rocky walls could enable a new class of persistent surveillance devices for military applications. In order to interface these microspine grippers with a legged robot, an ankle is needed that can robotically actuate the gripper, as well as allow it to conform to the large-scale irregularities in the rock. The anchor serves three main purposes: deploy and release the anchor, conform to roughness or misalignment with the surface, and cancel out any moments about the anchor that could cause unintentional detachment. The ankle design contains a

  15. A Survey of Parachute Ankle Brace Breakages

    Science.gov (United States)

    2008-01-10

    reduced since it was subject to abrasion from the concrete in the harness shed, asphalt on the loading ramp, and dirt on the drop zone. b. DJ...strap was also directly under the heel and subject to abrasion from concrete in the harness shed, asphalt on the loading ramp, and dirt on the drop...airborne injuries), airborne students who did not wear the brace were 1.90 times more likely to experience an ankle sprain, 1.47 times more likely to

  16. Stiff substrates enhance cultured neuronal network activity.

    Science.gov (United States)

    Zhang, Quan-You; Zhang, Yan-Yan; Xie, Jing; Li, Chen-Xu; Chen, Wei-Yi; Liu, Bai-Lin; Wu, Xiao-an; Li, Shu-Na; Huo, Bo; Jiang, Lin-Hua; Zhao, Hu-Cheng

    2014-08-28

    The mechanical property of extracellular matrix and cell-supporting substrates is known to modulate neuronal growth, differentiation, extension and branching. Here we show that substrate stiffness is an important microenvironmental cue, to which mouse hippocampal neurons respond and integrate into synapse formation and transmission in cultured neuronal network. Hippocampal neurons were cultured on polydimethylsiloxane substrates fabricated to have similar surface properties but a 10-fold difference in Young's modulus. Voltage-gated Ca(2+) channel currents determined by patch-clamp recording were greater in neurons on stiff substrates than on soft substrates. Ca(2+) oscillations in cultured neuronal network monitored using time-lapse single cell imaging increased in both amplitude and frequency among neurons on stiff substrates. Consistently, synaptic connectivity recorded by paired recording was enhanced between neurons on stiff substrates. Furthermore, spontaneous excitatory postsynaptic activity became greater and more frequent in neurons on stiff substrates. Evoked excitatory transmitter release and excitatory postsynaptic currents also were heightened at synapses between neurons on stiff substrates. Taken together, our results provide compelling evidence to show that substrate stiffness is an important biophysical factor modulating synapse connectivity and transmission in cultured hippocampal neuronal network. Such information is useful in designing instructive scaffolds or supporting substrates for neural tissue engineering.

  17. Dynamic stiffness of suction caissons - vertical vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Ibsen, Lars Bo; Liingaard, M.; Andersen, Lars

    2006-12-15

    The dynamic response of offshore wind turbines are affected by the properties of the foundation and the subsoil. The purpose of this report is to evaluate the dynamic soil-structure interaction of suction caissons for offshore wind turbines. The investigation is limited to a determination of the vertical dynamic stiffness of suction caissons. The soil surrounding the foundation is homogenous with linear viscoelastic properties. The dynamic stiffness of the suction caisson is expressed by dimensionless frequency-dependent dynamic stiffness coefficients corresponding to the vertical degree of freedom. The dynamic stiffness coefficients for the foundations are evaluated by means of a dynamic three-dimensional coupled Boundary Element/Finite Element model. Comparisons are made with known analytical and numerical solutions in order to evaluate the static and dynamic behaviour of the Boundary Element/Finite Element model. The vertical frequency dependent stiffness has been determined for different combinations of the skirt length, Poisson's ratio and the ratio between soil stiffness and skirt stiffness. Finally the dynamic behaviour at high frequencies is investigated. (au)

  18. [Influence of Ankle Braces on the Prevalence of Ankle Inversion Injuries in the Swiss Volleyball National League A].

    Science.gov (United States)

    Jaggi, J; Kneubühler, S; Rogan, S

    2016-06-01

    Ankle inversion is a common injury among volleyball players. The injury rate during a game is 2.1 times higher than during training. As a result, the preventive use of ankle braces is frequently observed in Swiss volleyball leagues. Studies have shown that ankle braces have a preventive effect on the prevalence of ankle inversion. In Switzerland there has been no investigation into the preventive use of braces and their influence on prevalence. For this reason, the goals of this study are 1) to determine when, why and by whom ankle braces are worn and 2) to evaluate the injury rate of users and non-users of ankle braces. A modified questionnaire was sent to 18 men's and women's teams of the Swiss National League A. The questionnaire included questions about injury rates and the circumstances of ankle inversion injuries. The data were statistically analysed with Microsoft Excel 2012 and SPSS Version 20. The overall response rate was 61 %, allowing data from 181 players to be analysed. 33 % (59 of 181) of the players used an ankle brace. There was a statistically significant difference in the prevalence of ankle inversion between users (12 injured) and non-users (8 injured) (p = 0.006). Wearing an ankle brace during training or during a game made no difference in the prevention of injuries (p = 0.356). More athletes were injured during training (n = 13) than during a game (n = 7). The results of the present study indicate that volleyball players preferably wear ankle braces to prevent injury. More than one third of the players in the study wore an ankle brace, 60 % for primary prevention and 40 % for secondary prevention due to a previous injury. The study shows that significantly more users than non-users of ankle braces were injured. This is contrary to literature. Furthermore it was shown that more injuries occur during training than during a game. This finding results from the fact that ankle braces were rarely worn during training. It is

  19. THE EFFECTS OF KINESIO TAPING ON PROPRIOCEPTION AT THE ANKLE

    Directory of Open Access Journals (Sweden)

    Mark DeBeliso

    2004-03-01

    Full Text Available An experiment was designed to determine if KinesioTM taping the anterior and lateral portion of the ankle would enhance ankle proprioception compared to the untaped ankle. 30 subjects, 15 men, 15 women, ages 18-30 participated in this study. Exclusion criteria: Ankle injury < 6 months prior to testing, significant ligament laxity as determined through clinical evaluation by an ATC, or any severe foot abnormality. Experiment utilized a single group, pretest and posttest. Plantar flexion and inversion with 20° of plantar flexion reproduction of joint position sense (RJPS was determined using an ankle RJPS apparatus. Subjects were barefooted, blindfolded, and equipped with headphones playing white noise to eliminate auditory cues. Subjects had five trials in both plantar flexion and inversion with 20° plantar flexion before and after application of the KinesioTM tape to the anterior/lateral portion of the ankle. Constant error and absolute error were determined from the difference between the target angle and the trial angle produced by the subject. The treatment group (KinesioTM taped subjects showed no change in constant and absolute error for ankle RJPS in plantar flexion and 20º of plantar flexion with inversion when compared to the untaped results using the same motions. The application of KinesioTM tape does not appear to enhance proprioception (in terms of RJPS in healthy individuals as determined by our measures of RJPS at the ankle in the motions of plantar flexion and 20º of plantar flexion with inversion.

  20. Hindfoot endoscopy for posterior ankle impingement. Surgical technique

    NARCIS (Netherlands)

    van Dijk, C.N.; de Leeuw, P.A.J.; Scholten, P.E.

    2009-01-01

    BACKGROUND: The surgical treatment of posterior ankle impingement is associated with a high rate of complications and a substantial time to recover. An endoscopic approach to the posterior ankle (hindfoot endoscopy) may lack these disadvantages. We hypothesized that hindfoot endoscopy causes less mo

  1. Dislocated ankle fracture complicated by near total distal ischaemia

    Science.gov (United States)

    Duygun, Fatih; Sertkaya, Omer; Aldemir, Cengiz; Dogan, Ali

    2013-01-01

    Total arterial ischaemia is rarely seen following a dislocated ankle fracture but if it does and intervention is not made, it can lead to serious morbidity. We present a 39-year-old woman with almost total occlusion in the arteria tibialis and arteria dorsalis pedis following a dislocated ankle fracture as a result of a bicycle fall. PMID:24248319

  2. Simultaneous bilateral total ankle replacement using a 3-component prosthesis

    Science.gov (United States)

    2011-01-01

    Background and purpose Total ankle replacement is an established surgical procedure in patients with end-stage ankle osteoarthritis. We analyzed complications and medium-term results in patients with simultaneous bilateral total ankle replacement. Patients and methods 10 women and 16 men, mean age 60 (SD 13) years, were followed for a median of 5 (2–10) years. Results There were no intraoperative or perioperative complications, with the exception of 1 patient with prolonged wound healing. Major revision surgery was necessary in 6 of the 52 ankles, including 4 revisions of prosthetic components. The average pain score decreased from 6.9 (4−10) to 1.8 (0−4) points. The American Orthopaedic Foot and Ankle Society hindfoot score increased from 32 (SD 14) points preoperatively to 74 (SD 12) points postoperatively. The average range of motion increased from 28° (SD 12) preoperatively to 38° (SD 9) postoperatively. All 8 categories of SF-36 score improved. Interpretation Simultaneous bilateral total ankle replacement is a suitable method for restoration of function and attainment of pain relief in patients with bilateral end-stage ankle osteoarthritis. The results of this procedure, including complication rates, revision rates, and functional outcome, are comparable to those reported in patients with unilateral total ankle replacement. PMID:21999622

  3. Medium- to long-term outcome of ankle arthrodesis

    NARCIS (Netherlands)

    R.P.M. Hendrickx; S.A.S. Stufkens; E.E. de Bruijn; I.N. Sierevelt; C.N. van Dijk; G.M.M.J. Kerkhoffs

    2011-01-01

    Despite improvement in outcome after ankle arthroplasty, fusion of the ankle joint is still considered the gold standard. A matter of concern is deterioration of clinical outcome as a result of loss of motion and advancing degeneration of adjacent joints. We performed a long-term study to address th

  4. Accelerated Solutions for Transcendental Stiffness Matrix Eigenproblems

    Directory of Open Access Journals (Sweden)

    F.W. Williams

    1996-01-01

    Full Text Available This article outlines many existing and forthcoming methods that can be used alone, or in various combinations, to accelerate the solutions of the transcendental stiffness matrix eigenproblems that arise when the stiffness matrix is assembled from exact member stiffnesses, which are obtained by solving the member differential equations exactly. Thus distributed member mass and/or the flexural effect of axial loading are incorporated exactly, and the solutions are the natural frequencies for vibration problems or the critical load factors for buckling problems.

  5. Human balancing of an inverted pendulum: position control by small, ballistic-like, throw and catch movements.

    Science.gov (United States)

    Loram, Ian D; Lakie, Martin

    2002-05-01

    In standing, there are small sways of the body. Our interest is to use an artificial task to illuminate the mechanisms underlying the sways and to account for changes in their size. Using the ankle musculature, subjects balanced a large inverted pendulum. The equilibrium of the pendulum is unstable and quasi-regular sway was observed like that in quiet standing. By giving full attention to minimising sway subjects could systematically reduce pendulum movement. The pendulum position, the torque generated at each ankle and the soleus and tibialis anterior EMGs were recorded. Explanations about how the human inverted pendulum is balanced usually ignore the fact that balance is maintained over a range of angles and not just at one angle. Any resting equilibrium position of the pendulum is unstable and in practice temporary; movement to a different resting equilibrium position can only be accomplished by a biphasic 'throw and catch' pattern of torque and not by an elastic mechanism. Results showed that balance was achieved by the constant repetition of a neurally generated ballistic-like biphasic pattern of torque which can control both position and sway size. A decomposition technique revealed that there was a substantial contribution to changes in torque from intrinsic mechanical ankle stiffness; however, by itself this was insufficient to maintain balance or to control position. Minimisation of sway size was caused by improvement in the accuracy of the anticipatory torque impulses. We hypothesise that examination of centre of mass and centre of pressure data for quiet standing will duplicate these results.

  6. Technique of Arthroscopic Treatment of Impingement After Total Ankle Arthroplasty.

    Science.gov (United States)

    Gross, Christopher E; Neumann, Julie A; Godin, Jonathan A; DeOrio, James K

    2016-04-01

    Rates of medial and/or lateral gutter impingement after total ankle replacement are not insignificant. If impingement should occur, it typically arises an average of 17 months after total ankle replacement. Our patient underwent treatment for right ankle medial gutter bony impingement with arthroscopic debridement 5 years after her initial total ankle replacement. Standard anteromedial and anterolateral portals and a 30° 2.7-mm-diameter arthroscope were used. An aggressive soft-tissue and bony resection was performed using a combination of curettes, a 3.5-mm shaver, a 5.5-mm unsheathed burr, a drill, and a radiofrequency ablator. This case shows that arthroscopic treatment is an effective and potentially advantageous alternative to open treatment of impingement after total ankle replacement. In addition, symptoms of impingement often improve in a short amount of time after arthroscopic debridement of the medial and/or lateral gutter.

  7. Total ankle replacement – surgical treatment and rehabilitation

    Science.gov (United States)

    Krogulec, Zbigniew; Turski, Piotr; Przepiórski, Emil; Małdyk, Paweł; Księżopolska-Orłowska, Krystyna

    2015-01-01

    Functions of the ankle joint are closely connected with the gait and ability to maintain an upright position. Degenerative lesions of the joint directly contribute to postural disorders and greatly restrict propulsion of the foot, thus leading to abnormal gait. Development of total ankle replacement is connected with the use of the method as an efficient treatment of joint injuries and continuation of achievements in hip and knee surgery. The total ankle replacement technique was introduced as an alternative to arthrodesis, i.e. surgical fixation, which made it possible to preserve joint mobility and to improve gait. Total ankle replacement is indicated in post-traumatic degenerative joint disease and joint destruction secondary to rheumatoid arthritis. In this paper, total ankle replacement and various types of currently used endoprostheses are discussed. The authors also describe principles of early postoperative rehabilitation as well as rehabilitation in the outpatient setting. PMID:27407223

  8. Finite element analysis of a composite artificial ankle

    Science.gov (United States)

    Perkins, Leigh Ann; Johnston, Lawrence; Denniston, Charles; Czekalski, Blaise E.

    1993-01-01

    Ultra-light carbon fiber composite materials are being utilized in artificial limbs with increasing frequency in recent years. Dr. Arthur Copes, an orthotist from Baton Rouge, Louisiana, has developed a graphite expoxy composite material artificial ankle (Copes/Bionic Ankle) that is intended to be used by amputees who require the most advanced above-and-below-the-knee prosthetic devices. The Copes/Bionic Ankle is designed to reproduce the function of the natural ankle joint by allowing the composite material to act as a spring mechanism without the use of metal mechanical parts. NASA Marshall Space Flight Center has agreed to participate in the design effort by providing the structural analysis of the artificial ankle design.

  9. A pneumatically powered knee-ankle-foot orthosis (KAFO) with myoelectric activation and inhibition.

    Science.gov (United States)

    Sawicki, Gregory S; Ferris, Daniel P

    2009-06-23

    The goal of this study was to test the mechanical performance of a prototype knee-ankle-foot orthosis (KAFO) powered by artificial pneumatic muscles during human walking. We had previously built a powered ankle-foot orthosis (AFO) and used it effectively in studies on human motor adaptation, locomotion energetics, and gait rehabilitation. Extending the previous AFO to a KAFO presented additional challenges related to the force-length properties of the artificial pneumatic muscles and the presence of multiple antagonistic artificial pneumatic muscle pairs. Three healthy males were fitted with custom KAFOs equipped with artificial pneumatic muscles to power ankle plantar flexion/dorsiflexion and knee extension/flexion. Subjects walked over ground at 1.25 m/s under four conditions without extensive practice: 1) without wearing the orthosis, 2) wearing the orthosis with artificial muscles turned off, 3) wearing the orthosis activated under direct proportional myoelectric control, and 4) wearing the orthosis activated under proportional myoelectric control with flexor inhibition produced by leg extensor muscle activation. We collected joint kinematics, ground reaction forces, electromyography, and orthosis kinetics. The KAFO produced approximately 22%-33% of the peak knee flexor moment, approximately 15%-33% of the peak extensor moment, approximately 42%-46% of the peak plantar flexor moment, and approximately 83%-129% of the peak dorsiflexor moment during normal walking. With flexor inhibition produced by leg extensor muscle activation, ankle (Pearson r-value = 0.74 +/- 0.04) and knee ( r = 0.95 +/- 0.04) joint kinematic profiles were more similar to the without orthosis condition compared to when there was no flexor inhibition (r = 0.49 +/- 0.13 for ankle, p = 0.05, and r = 0.90 +/- 0.03 for knee, p = 0.17). The proportional myoelectric control with flexor inhibition allowed for a more normal gait than direct proportional myoelectric control. The current orthosis

  10. A pneumatically powered knee-ankle-foot orthosis (KAFO with myoelectric activation and inhibition

    Directory of Open Access Journals (Sweden)

    Ferris Daniel P

    2009-06-01

    Full Text Available Abstract Background The goal of this study was to test the mechanical performance of a prototype knee-ankle-foot orthosis (KAFO powered by artificial pneumatic muscles during human walking. We had previously built a powered ankle-foot orthosis (AFO and used it effectively in studies on human motor adaptation, locomotion energetics, and gait rehabilitation. Extending the previous AFO to a KAFO presented additional challenges related to the force-length properties of the artificial pneumatic muscles and the presence of multiple antagonistic artificial pneumatic muscle pairs. Methods Three healthy males were fitted with custom KAFOs equipped with artificial pneumatic muscles to power ankle plantar flexion/dorsiflexion and knee extension/flexion. Subjects walked over ground at 1.25 m/s under four conditions without extensive practice: 1 without wearing the orthosis, 2 wearing the orthosis with artificial muscles turned off, 3 wearing the orthosis activated under direct proportional myoelectric control, and 4 wearing the orthosis activated under proportional myoelectric control with flexor inhibition produced by leg extensor muscle activation. We collected joint kinematics, ground reaction forces, electromyography, and orthosis kinetics. Results The KAFO produced ~22%–33% of the peak knee flexor moment, ~15%–33% of the peak extensor moment, ~42%–46% of the peak plantar flexor moment, and ~83%–129% of the peak dorsiflexor moment during normal walking. With flexor inhibition produced by leg extensor muscle activation, ankle (Pearson r-value = 0.74 ± 0.04 and knee ( r = 0.95 ± 0.04 joint kinematic profiles were more similar to the without orthosis condition compared to when there was no flexor inhibition (r = 0.49 ± 0.13 for ankle, p = 0.05, and r = 0.90 ± 0.03 for knee, p = 0.17. Conclusion The proportional myoelectric control with flexor inhibition allowed for a more normal gait than direct proportional myoelectric control. The current

  11. The endogenous fluorescence of fibroblast in collagen gels as indicator of stiffness of the extracellular matrix

    Science.gov (United States)

    Padilla-Martinez, J. P.; Ortega-Martinez, A.; Franco, W.

    2016-03-01

    The stiffness or rigidity of the extracellular matrix (ECM) regulates cell response. Established mechanical tests to measure stiffness, such as indentation and tensile tests, are invasive and destructive to the sample. Endogenous or native molecules to cells and ECM components, like tryptophan and cross-links of collagen, display fluorescence upon irradiation with ultraviolet light. Most likely, the concentration of these endogenous fluorophores changes as the stiffness of the ECM changes. In this work we investigate the endogenous fluorescence of collagen gels containing fibroblasts as a non-invasive non-destructive method to measure stiffness of the ECM. Human fibroblast cells were cultured in three-dimensional gels of type I collagen (50,000 cells/ml). This construct is a simple model of tissue contraction. During contraction, changes in the excitation-emission matrix (a fluorescence map in the 240-520/290-530 nm range) of constructs were measured with a spectrofluoremeter, and changes in stiffness were measured with a standard indentation test over 16 days. Results show that a progressive increase in fluorescence of the 290/340 nm excitation-emission pair correlates with a progressive increase in stiffness (r=0.9, α=0.5). The fluorescence of this excitation-emission pair is ascribed to tryptophan and variations in the fluorescence of this pair correlate with cellular proliferation. In this tissue model, the endogenous functional fluorescence of proliferating fibroblast cells is a biomechanical marker of stiffness of the ECM.

  12. Vascular Aging and Arterial Stiffness.

    Science.gov (United States)

    Mikael, Luana de Rezende; Paiva, Anelise Machado Gomes de; Gomes, Marco Mota; Sousa, Ana Luiza Lima; Jardim, Paulo César Brandão Veiga; Vitorino, Priscila Valverde de Oliveira; Euzébio, Maicon Borges; Sousa, Wátila de Moura; Barroso, Weimar Kunz Sebba

    2017-06-29

    Cardiovascular diseases (CVD) account annually for almost one third of all deaths worldwide. Among the CVD, systemic arterial hypertension (SAH) is related to more than half of those outcomes. Type 2 diabetes mellitus is an independent risk factor for SAH because it causes functional and structural damage to the arterial wall, leading to stiffness. Several studies have related oxidative stress, production of free radicals, and neuroendocrine and genetic changes to the physiopathogenesis of vascular aging. Indirect ways to analyze that aging process have been widely studied, pulse wave velocity (PWV) being considered gold standard to assess arterial stiffness, because there is large epidemiological evidence of its predictive value for cardiovascular events, and it requires little technical knowledge to be performed. A pulse wave is generated during each cardiac contraction and travels along the arterial bed until finding peripheral resistance or any bifurcation point, determining the appearance of a reflected wave. In young individuals, arteries tend to be more elastic, therefore, the reflected wave occurs later in the cardiac cycle, reaching the heart during diastole. In older individuals, however, the reflected wave occurs earlier, reaching the heart during systole. Because PWV is an important biomarker of vascular damage, highly valuable in determining the patient's global cardiovascular risk, we chose to review the articles on vascular aging in the context of cardiovascular risk factors and the tools available to the early identification of that damage. Resumo As doenças cardiovasculares são anualmente responsáveis por quase um terço do total de mortes no mundo. Dentre elas, a hipertensão arterial sistêmica (HAS) está relacionada com mais da metade desses desfechos. O diabetes mellitus tipo 2 é visto com um fator de risco independente para HAS por causar lesões funcionais e estruturais na parede arterial, ocasionando-lhe enrijecimento. Diversos estudos

  13. Ankle tuberculosis. A case in childhood.

    Science.gov (United States)

    Navarrete, F E; Gómez-Alessandri, J; Tintó, M; Sánchez-González, M; Vicent, V

    Articular tuberculosis of the ankle joint is a rare presentation of skeletal tuberculosis (10% of cases). This unusual location and the low index of clinical suspicion leads to delays in diagnosis and treatment. Radiographic and analytic studies are unspecific in the first stage. CAT and MRI are useful in diagnosis. Chemotherapy is the mainstay of treatment and surgery is often required to establish the diagnosis and in the treatment. We report a case of ankle tuberculosis in a 22 month-old child. The diagnosis was confirmed by synovial biopsy. There was no patient or family contact with tuberculosis patients. There was no risk factor. There was no lung disease. Diagnosis was made 1 year after onset of symptoms. The treatment was with chemotherapy and surgery was performed as preventive treatment of equinus deformity and osteoarthritis. Good clinical and functional outcome was achieved after 20 years of follow up. Copyright © 2017 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

  14. A high normal ankle-brachial index combined with a high pulse wave velocity is associated with cerebral microbleeds.

    Science.gov (United States)

    Kinjo, Yoshino; Ishida, Akio; Kinjo, Kozen; Ohya, Yusuke

    2016-08-01

    Arterial stiffness is associated with the pathogenesis of cerebral microbleeds (CMBs). The ankle-brachial index (ABI) is used to predict arterial stiffness. We hypothesized that the increase in ABI with age occurs as a result of increasing arterial stiffness and wave reflection, and is thus associated with target organ damage. The aim of this study was to investigate the relationship between ABI, brachial-ankle pulse wave velocity (baPWV), and CMBs. We recruited 990 cardiovascular disease-free and stroke-free participants [median age 53 (24-86) years, 531 were woman] who underwent brain MRI, ABI, and baPWV at a health checkup. The prevalence of CMBs was 4%. Both ABI (1.14 vs. 1.10) and baPWV (17.29 vs. 14.68 m/s) were higher in participants with CMBs than those without. Cutoff values of ABI and baPWV for the presence of CMBs were 1.12 and 16.07 m/s, respectively. Multivariate logistic regression analysis showed that ABI at least 1.12 [odds ratio (OR) 2.57, 95% confidence interval (CI) 1.30-5.37, P CMBs. Moreover, the combination of ABI at least 1.12 and baPWV at least 16.07 m/s was strongly associated with CMBs (OR 5.26, 95% CI 1.93-16.92, P CMBs in a screened Japanese cohort, suggesting a novel use for ABI as a predictor for target organ damage.

  15. Effects of chronic ankle instability and induced mediolateral muscular fatigue of the ankle on competitive taekwondo athletes.

    Science.gov (United States)

    Lee, Myeounggon; Youm, Changhong; Son, Minji; Kim, Jinhee; Kim, Youkyung

    2017-08-01

    [Purpose] The purpose of this study was to investigate the effects of chronic ankle instability and induced mediolateral muscular fatigue of the ankle on competitive Taekwondo athletes during single-leg drop landing. [Subjects and Methods] Fourteen competitive taekwondo athletes with chronic ankle instability and 14 healthy adults participated, and they performed three single-leg drop landings from a 40-cm height before and after induced fatigue. Ankle angular position, peak vertical ground reaction force, loading rate, eccentric work, and contribution were calculated and analyzed. [Results] Athletes had lower ankle eversion and abduction angle than the controls did at maximum knee flexion both pre- and post-fatigue. Furthermore, athletes had lower eccentric work of the hip than the controls did post-fatigue, and they had lower eccentric work of the knee than controls at both pre- and post-fatigue. The eccentric work of the knee increased while, peak vertical ground reaction force decreased in both, athletes as well as controls post-fatigue. [Conclusion] Taekwondo athletes with chronic ankle instability who participate in a high-intensity training program are continuously exposed to potential injuries of their ankle or knee joints. Therefore, competitive taekwondo athletes with chronic ankle instability should limit their participation in regular training until they complete the rehabilitation process.

  16. Stiff Neck, Torticollis, and Pseudotumor Cerebri

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2002-05-01

    Full Text Available Three prepubertal children diagnosed with pseudotumor cerebri and presenting with stiff neck and torticollis are reported from Schneider Children’s Medical Center, Sackler School of Medicine, Tel Aviv, Israel.

  17. Observed variations of monopile foundation stiffness

    DEFF Research Database (Denmark)

    Kallehave, Dan; Thilsted, C.L.; Diaz, Alberto Troya

    2015-01-01

    The soil-structure stiffness of monopile foundations for offshore wind turbines has a high impact on the fatigue loading during normal operating conditions. Thus, a robust design must consider the evolution of pile-soil stiffness over the lifetime of the wind farm. This paper present and discuss...... full-scale measurements obtained from one offshore wind turbine structure located within Horns Reef II offshore wind farm. Data are presented for a 2.5 years period and covers normal operating conditions and one larger storm event. A reduction of the pile-soil stiffness was observed during the storm...... events, followed by a complete regain to a pre-storm level when the storm subsided. In additional, no long term variations of the pile-soil stiffness was observed. The wind turbine is located in dense to very dense sand deposits....

  18. Strength and stiffness of engineering systems

    CERN Document Server

    Leckie, Frederick A

    2009-01-01

    This book on the stiffness and strength of engineering systems integrates a wide array of topics into a unified text, including plasticity, fracture, composite materials, energy approaches, and mechanics of microdevices (MEMs)..

  19. Vascular Stiffness in Insulin Resistance and Obesity

    Directory of Open Access Journals (Sweden)

    Guanghong eJia

    2015-08-01

    Full Text Available Obesity, insulin resistance, and type 2 diabetes are associated with a substantially increased prevalence of vascular fibrosis and stiffness, with attendant increased risk of cardiovascular and chronic kidney disease. Although the underlying mechanisms and mediators of vascular stiffness are not well understood, accumulating evidence supports the role of metabolic and immune dysregulation related to increased adiposity, activation of the renin angiotensin aldosterone system, reduced bioavailable nitric oxide, increased vascular extracellular matrix (ECM and ECM remodeling in the pathogenesis of vascular stiffness. This review will give a brief overview of the relationship between obesity, insulin resistance and increased vascular stiffness to provide a contemporary understanding of the proposed underlying mechanisms and potential therapeutic strategies.

  20. Stiff person syndrome and myasthenia gravis.

    Directory of Open Access Journals (Sweden)

    Saravanan P

    2002-01-01

    Full Text Available Association of stiff person syndrome, an immune related disorder of anterior horn cells and myasthenia gravis an endplate disorder with similar pathogenesis, is rare. This communication documents this association in the Indian literature for the first time.

  1. Determination of 6 stiffnesses for a press

    DEFF Research Database (Denmark)

    Arentoft, Mogens; Eriksen, Morten; Wanheim, Tarras

    2000-01-01

    The industry is increasingly demanding for better tolerances at cold forged products caused by the tough competition at the market. Near net-shape or net-shape production save resources for machining and reduce therefore also the material costs. During the forming process, the reaction forces fro...... in which the press has the highest stiffness. Furthermore, knowledge about the stiffnesses of all presses in a production system makes it possible to choose the press which best fit to a specific process....... is known too, the final dimensions can be predicted by divide the force by the stiffness and add the clearance. If the stiffness of the press is known, it is possible to optimize the orientation of the workpiece too, so the direction, in which the best tolerances is demanded, is equal to the direction...

  2. Serum Uric Acid Level and Diverse Impacts on Regional Arterial Stiffness and Wave Reflection

    Directory of Open Access Journals (Sweden)

    Suyan Bian

    2012-08-01

    Full Text Available Background: Both increased arterial stiffness and hyperuricaemia are associated with elevated cardiovascular risks. Little is known about the relations of serum uric acid (UA level to regional arterial stiffness and wave reflection. The aim of the study was to investigate the gender-specific association of serum UA and indices of arterial function in a community-based investigation in China.Methods: Cross-sectional data from 2374 adults (mean age 58.24 years who underwent routine laboratory tests, regional pulse wave velocity (PWV and pulse wave analysis measurements were analyzed in a gender-specific manner. None of the participants had atherosclerotic cardiovascular disease, chronic renal failure, systemic inflammatory disease, gout, or were under treatment which would affect serum UA level.Results: Men had higher serum UA level than women. Subjects with hyperuricaemia had significantly higher carotid-ankle PWV in both genders (P< 0.05, and the carotid-femoral PWV (PWVc-f was higher in women (P< 0.001 while the augmentation index was marginally lower in men (P = 0.049. Multiple regression analysis showed that serum UA was an independent determinant only for PWVc-f in women (β = 0.104, P = 0.027 when adjusted for atherogenic confounders. No other independent relationship was found between UA level and other surrogates of arterial stiffness.Conclusions: Serum UA levels are associated with alterations in systemic arterial stiffness that differ in men and women. Women might be more susceptible to large vascular damage associated with hyperuricaemia.

  3. Association between Urine Creatinine Excretion and Arterial Stiffness in Chronic Kidney Disease: Data from the KNOW-CKD Study

    Directory of Open Access Journals (Sweden)

    Young Youl Hyun

    2016-08-01

    Full Text Available Background/Aims: Previous studies have shown that low muscle mass is associated with arterial stiffness, as measured by pulse wave velocity (PWV, in a population without chronic kidney disease (CKD. This link between low muscle mass and arterial stiffness may explain why patients with CKD have poor cardiovascular outcomes. However, the association between muscle mass and arterial stiffness in CKD patients is not well known. Methods: Between 2011 and 2013, 1,529 CKD patients were enrolled in the prospective Korean Cohort Study for Outcome in Patients With Chronic Kidney Disease (KNOW-CKD. We analyzed 888 participants from this cohort who underwent measurements of 24-hr urinary creatinine excretion (UCr and brachial-ankle PWV (baPWV at baseline examination. The mean of the right and left baPWV (mPWV was used as a marker of arterial stiffness. Results: The baPWV values varied according to the UCr quartile (1,630±412, 1,544±387, 1,527±282 and 1,406±246 for the 1st to 4th quartiles of UCr, respectively, PConclusion: Low muscle mass estimated by low UCr was associated high baPWV in pre-dialysis CKD patients in Korea. Further studies are needed to confirm the causal relationship between UCR and baPWV, and the role of muscle mass in the development of cardiovascular disease in CKD.

  4. Effect of yoga on arterial stiffness in elderly subjects with increased pulse pressure: A randomized controlled study.

    Science.gov (United States)

    Patil, Satish Gurunathrao; Aithala, Manjunatha R; Das, Kusal Kanti

    2015-08-01

    We aimed to determine the effect of yoga on arterial function in elderly with increased pulse pressure (PP). Randomized controlled study with two parallel groups. Elderly subjects with PP≥60 mmHg (n=60). Yoga group (n=30) was assigned for yoga training and brisk-walking (BW) group (n=30) for brisk-walk with stretching exercise for 1h in the morning for 6 days in a week for 12 weeks. Arterial stiffness measures: Brachial-ankle pulse wave velocity (baPWV), Carotid-femoral pulse wave velocity (c-f PWV), aortic augmentation index (AIx@75), arterial stiffness index at brachial (bASI) and tibial arteries (aASI). Total serum nitric oxide concentration (NOx) as an index of endothelial function. Heart rate variability (HRV) measures: Low frequency and high frequency in normalized units (LFnu, HFnu) and LF/HF ratio. The mean between-group change (with 95% CI) in arterial stiffness: c-f PWV(m/s) [1.25(0.59-1.89); pyoga group in vascular function, BP and autonomic function, while no significant change within-BW group was observed. Our findings suggest that yoga program offered was more effective than brisk-walk in reducing arterial stiffness along with BP in elderly individuals with increased PP. Yoga can also significantly reduce sympathetic activity and improve endothelial function with enhancement in bioavailability of NO. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Effects of aerobic exercise on the resting heart rate, physical fitness, and arterial stiffness of female patients with metabolic syndrome.

    Science.gov (United States)

    Kang, Seol-Jung; Kim, Eon-Ho; Ko, Kwang-Jun

    2016-06-01

    [Purpose] The purpose of this study was to investigate the effects of aerobic exercise on the resting heart rate, physical fitness, and arterial stiffness or female patients with metabolic syndrome. [Subjects and Methods] Subjects were randomly assigned to an exercise group (n=12) or a control group (n=11). Subjects in the exercise group performed aerobic exercise at 60-80% of maximum heart rate for 40 min 5 times a week for 12 weeks. The changes in metabolic syndrome risk factors, resting heart rate, physical fitness, and arterial stiffness were measured and analyzed before and after initiation of the exercise program to determine the effect of exercise. Arterial stiffness was assessed based on brachial-ankle pulse wave velocity (ba-PWV). [Results] Compared to the control group; The metabolic syndrome risk factors (weight, % body fat, waist circumference, systolic blood pressure, diastolic blood pressure, and HDL-Cholesterol) were significantly improved in the exercise: resting heart rate was significantly decreased; VO2max, muscle strength and muscle endurance were significantly increased; and ba-PWV was significantly decreased. [Conclusion] Aerobic exercise had beneficial effects on the resting heart rate, physical fitness, and arterial stiffness of patients with metabolic syndrome.

  6. Assessment of a virtual functional prototyping process for the rapid manufacture of passive-dynamic ankle-foot orthoses.

    Science.gov (United States)

    Schrank, Elisa S; Hitch, Lester; Wallace, Kevin; Moore, Richard; Stanhope, Steven J

    2013-10-01

    Passive-dynamic ankle-foot orthosis (PD-AFO) bending stiffness is a key functional characteristic for achieving enhanced gait function. However, current orthosis customization methods inhibit objective premanufacture tuning of the PD-AFO bending stiffness, making optimization of orthosis function challenging. We have developed a novel virtual functional prototyping (VFP) process, which harnesses the strengths of computer aided design (CAD) model parameterization and finite element analysis, to quantitatively tune and predict the functional characteristics of a PD-AFO, which is rapidly manufactured via fused deposition modeling (FDM). The purpose of this study was to assess the VFP process for PD-AFO bending stiffness. A PD-AFO CAD model was customized for a healthy subject and tuned to four bending stiffness values via VFP. Two sets of each tuned model were fabricated via FDM using medical-grade polycarbonate (PC-ISO). Dimensional accuracy of the fabricated orthoses was excellent (average 0.51 ± 0.39 mm). Manufacturing precision ranged from 0.0 to 0.74 Nm/deg (average 0.30 ± 0.36 Nm/deg). Bending stiffness prediction accuracy was within 1 Nm/deg using the manufacturer provided PC-ISO elastic modulus (average 0.48 ± 0.35 Nm/deg). Using an experimentally derived PC-ISO elastic modulus improved the optimized bending stiffness prediction accuracy (average 0.29 ± 0.57 Nm/deg). Robustness of the derived modulus was tested by carrying out the VFP process for a disparate subject, tuning the PD-AFO model to five bending stiffness values. For this disparate subject, bending stiffness prediction accuracy was strong (average 0.20 ± 0.14 Nm/deg). Overall, the VFP process had excellent dimensional accuracy, good manufacturing precision, and strong prediction accuracy with the derived modulus. Implementing VFP as part of our PD-AFO customization and manufacturing framework, which also includes fit customization, provides a novel and powerful method to

  7. Vascular Physiology according to Clinical Scenario in Patients with Acute Heart Failure: Evaluation using the Cardio-Ankle Vascular Index.

    Science.gov (United States)

    Goto, Toshihiko; Wakami, Kazuaki; Mori, Kento; Kikuchi, Shohei; Fukuta, Hidekatsu; Ohte, Nobuyuki

    2016-01-01

    Increased aortic stiffness may be an important cause of acute heart failure (AHF). Clinical scenario (CS), which classifies the pathophysiology of AHF based on the initial systolic blood pressure (sBP), was proposed to provide the most appropriate therapy for AHF patients. In CS, elevated aortic stiffness, vascular failure, has been considered as a feature of patients categorized as CS1 (sBP > 140 mmHg at initial presentation). However, whether elevated aortic stiffness, vascular failure, is present in such patients has not been fully elucidated. Therefore, we assessed aortic stiffness in AHF patients using the cardio-ankle vascular index (CAVI), which is considered to be independent of instantaneous blood pressure. Sixty-four consecutive AHF patients (mean age, 70.6 ± 12.8 years; 39 men) were classified with CS, based on their initial sBP: CS1: sBP > 140 mmHg (n = 29); CS2: sBP 100-140 mmHg (n = 22); and CS3: sBP 100 mmHg (n = 13). There were significant group differences in CAVI (CS1 vs. CS2 vs. CS3: 9.7 ± 1.4 vs. 8.4 ± 1.7 vs. 8.3 ± 1.7, p = 0.006, analysis of variance). CAVI was significantly higher in CS1 than in CS2 (p = 0.02) and CS3 (p = 0.04). CAVI did not significantly correlate with sBP at the time of measurement of CAVI (r = 0.24 and p = 0.06). Aortic stiffness assessed using blood pressure-independent methodology apparently increased in CS1 AHF patients. We conclude that vascular failure is a feature of CS1 AHF initiation.

  8. Arterial pressure suffices to increase liver stiffness.

    Science.gov (United States)

    Piecha, Felix; Peccerella, Teresa; Bruckner, Tom; Seitz, Helmut-Karl; Rausch, Vanessa; Mueller, Sebastian

    2016-11-01

    Noninvasive measurement of liver stiffness (LS) has been established to screen for liver fibrosis. Since LS is also elevated in response to pressure-related conditions such as liver congestion, this study was undertaken to learn more about the role of arterial pressure on LS. LS was measured by transient elastography (μFibroscan platform, Echosens, Paris, France) during single intravenous injections of catecholamines in anesthetized rats with and without thioacetamide (TAA)-induced fibrosis. The effect of vasodilating glycerol trinitrate (GTN) on LS was also studied. Pressures in the abdominal aorta and caval and portal veins were measured in real time with the PowerLab device (AD Instruments, Dunedin, New Zealand). Baseline LS values in all rats (3.8 ± 0.5 kPa, n = 25) did not significantly differ from those in humans. Epinephrine and norepinephrine drastically increased mean arterial pressure (MAP) from 82 to 173 and 156 mmHg. Concomitantly, LS almost doubled from 4 to 8 kPa, while central venous pressure remained unchanged. Likewise, portal pressure only showed a slight and delayed increase. In the TAA-induced fibrosis model, LS increased from 9.5 ± 1.0 to 25.6 ± 14.7 kPa upon epinephrine injection and could efficiently be decreased by GTN. We finally show a direct association in humans in a physiological setting of elevated cardiac output and MAP. During continuous spinning at 200 W, MAP increased from 84 ± 8 to 99 ± 11 mmHg while LS significantly increased from 4.4 ± 1.8 to 6.7 ± 2.1 kPa. In conclusion, our data show that arterial pressure suffices to increase LS. Moreover, lowering MAP efficiently decreases LS in fibrotic livers that are predominantly supplied by arterial blood. Copyright © 2016 the American Physiological Society.

  9. Numerical assessment of the stiffness index.

    Science.gov (United States)

    Epstein, Sally; Vergnaud, Anne-Claire; Elliott, Paul; Chowienczyk, Phil; Alastruey, Jordi

    2014-01-01

    Elevated systemic vascular stiffness is associated with increased risk of cardiovascular disease. It has been suggested that the time difference between the two characteristic peaks of the digital volume pulse (DVP) measured at the finger using photoplethysmography is related to the stiffness of the arterial tree, and inversely proportional to the stiffness index (SI). However, the precise physical meaning of the SI and its relation to aortic pulse wave velocity (aPWV) is yet to be ascertained. In this study we investigated numerically the effect of changes in arterial wall stiffness, peripheral resistances, peripheral compliances or peripheral wave reflections on the SI and aPWV. The SI was calculated from the digital area waveform simulated using a nonlinear one-dimensional model of pulse wave propagation in a 75-artery network, which includes the larger arteries of the hand. Our results show that aPWV is affected by changes in aortic stiffness, but the SI is primarily affected by changes in the stiffness of all conduit vessels. Thus, the SI is not a direct substitute for aPWV. Moreover, our results suggest that peripheral reflections in the upper body delay the time of arrival of the first peak in the DVP. The second peak is predominantly caused by the impedance mismatch within the 75 arterial segments, rather than by peripheral reflections.

  10. Stiffness of Railway Soil-Steel Structures

    Science.gov (United States)

    Machelski, Czesław

    2015-12-01

    The considerable influence of the soil backfill properties and that of the method of compacting it on the stiffness of soil-steel structures is characteristic of the latter. The above factors (exhibiting randomness) become apparent in shell deformation measurements conducted during construction and proof test loading. A definition of soil-shell structure stiffness, calculated on the basis of shell deflection under the service load, is proposed in the paper. It is demonstrated that the stiffness is the inverse of the deflection influence function used in structural mechanics. The moving load methodology is shown to be useful for testing, since it makes it possible to map the shell deflection influence line also in the case of group loads (concentrated forces), as in bridges. The analyzed cases show that the shell's span, geometry (static scheme) and the height of earth fill influence the stiffness of the structure. The soil-steel structure's characteristic parameter in the form of stiffness k is more suitable for assessing the quality of construction works than the proposed in code geometric index ω applied to beam structures. As shown in the given examples, parameter k is more effective than stiffness parameter λ used to estimate the deformation of soil-steel structures under construction. Although the examples concern railway structures, the methodology proposed in the paper is suitable also for road bridges.

  11. Microenvironmental stiffness enhances glioma cell proliferation by stimulating epidermal growth factor receptor signaling.

    Directory of Open Access Journals (Sweden)

    Vaibhavi Umesh

    Full Text Available The aggressive and rapidly lethal brain tumor glioblastoma (GBM is associated with profound tissue stiffening and genomic lesions in key members of the epidermal growth factor receptor (EGFR pathway. Previous studies from our laboratory have shown that increasing microenvironmental stiffness in culture can strongly enhance glioma cell behaviors relevant to tumor progression, including proliferation, yet it has remained unclear whether stiffness and EGFR regulate proliferation through common or independent signaling mechanisms. Here we test the hypothesis that microenvironmental stiffness regulates cell cycle progression and proliferation in GBM tumor cells by altering EGFR-dependent signaling. We began by performing an unbiased reverse phase protein array screen, which revealed that stiffness modulates expression and phosphorylation of a broad range of signals relevant to proliferation, including members of the EGFR pathway. We subsequently found that culturing human GBM tumor cells on progressively stiffer culture substrates both dramatically increases proliferation and facilitates passage through the G1/S checkpoint of the cell cycle, consistent with an EGFR-dependent process. Western Blots showed that increasing microenvironmental stiffness enhances the expression and phosphorylation of EGFR and its downstream effector Akt. Pharmacological loss-of-function studies revealed that the stiffness-sensitivity of proliferation is strongly blunted by inhibition of EGFR, Akt, or PI3 kinase. Finally, we observed that stiffness strongly regulates EGFR clustering, with phosphorylated EGFR condensing into vinculin-positive focal adhesions on stiff substrates and dispersing as microenvironmental stiffness falls to physiological levels. Our findings collectively support a model in which tissue stiffening promotes GBM proliferation by spatially and biochemically amplifying EGFR signaling.

  12. 主动型仿生踝关节假肢的设计%Design of powered bionic ankle prosthesis

    Institute of Scientific and Technical Information of China (English)

    赵改平; 曹帅; 尚昆; 阮超; 赵伟钦; 王祯祥; 郭丹

    2011-01-01

    背景:与髋、膝关节假肢设计相对比较成熟的技术相比,踝关节作为人体下肢关节的重要组成部分,也是最为灵活的部分,一直以来研究都比较滞后,相关的假肢踝关节产品未能很好的满足假肢患者的需求.目的:从生物力学、解剖学和生理学角度出发,设计和研制出能在矢状面内做屈伸运动的主动型仿生踝关节假肢装置.方法:根据仿生学原理和人体踝关节在步态行走时的受力特点和生理功能,建立二自由度的主动型仿生踝关节的力学模型,设计假肢踝关节的机械结构与控制系统,其主要部件包括仿生踝关节系统、辅助装置、数据控制系统和数据采集系统.结果与结论:利用研制出的踝关节装置进行系统测试,使用正常人行走时的踝关节角度数据作为输入信号,以步进电机作为动力驱动实现模拟踝关节的运动,通过数据采集系统获得输出的角度数据.测试结果表明仿生踝关节能够跟随输入角度数据运动,实现了仿生踝关节跟随运动的预期目标.%BACKGROUND: Ankle prosthesis has been researched as a focus point for improving living quality of disabled persons suffers from lower limb.OBJECTIVE: To design and manufacture the powered bionic ankle prosthesis based on biomechanics, anatomy and physiology theories.METHODS: According to bionics principle, the stress characteristics and physiological functions of the human ankle joint during gait analysis, mechanics model of ankle prosthesis with two-degree-of-freedom motion is established and mechanical structure and control system of ankle prosthesis are designed. The bionic ankle prosthesis, which includes bionic ankle system, auxiliary devices, data control and data acquisition systems, can do flexion and extension in the sagittal plane.RESULTS AND CONCLUSION: A system testing was performed based on the ankle prosthesis device. The normal human ankle walking gait data as the input signal

  13. Stiffness Effects in Rocker-Soled Shoes: Biomechanical Implications

    Science.gov (United States)

    Su, Pei-Fang; Chung, Chia-Hua; Hsia, Chi-Chun; Chang, Chih-Han

    2017-01-01

    Rocker-soled shoes provide a way to reduce the possible concentration of stress, as well as change movement patterns, during gait. This study attempts to examine how plantar force and spatio-temporal variables are affected by two rocker designs, one with softer and one with denser sole materials, by comparing them with the barefoot condition and with flat-soled shoes. Eleven subjects’ gait parameters during walking and jogging were recorded. Our results showed that compared with barefoot walking, plantar forces were higher for flat shoes while lower for both types of rocker shoes, the softer-material rocker being the lowest. The plantar force of flat shoes is greater than the vertical ground reaction force, while that of both rocker shoes is much less, 13.87–30.55% body weight. However, as locomotion speed increased to jogging, for all shoe types, except at the second peak plantar force of the denser sole material rocker shoes, plantar forces were greater than for bare feet. More interestingly, because the transmission of force was faster while jogging, greater plantar force was seen in the rocker-soled shoes with softer material than with denser material; results for higher-speed shock absorption in rocker-soled shoes with softer material were thus not as good. In general, the rolling phenomena along the bottom surface of the rocker shoes, as well as an increase in the duration of simultaneous curve rolling and ankle rotation, could contribute to the reduction of plantar force for both rocker designs. The possible mechanism is the conversion of vertical kinetic energy into rotational kinetic energy. To conclude, since plantar force is related to foot-ground interface and deceleration methods, rocker-design shoes could achieve desired plantar force reduction through certain rolling phenomena, shoe-sole stiffness levels, and locomotion speeds. PMID:28046009

  14. Stiffness compatibility of coralline hydroxyapatite bone substitute under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    REN ChaoFeng; HOU ZhenDe; ZHAO Wei

    2009-01-01

    When hydroxyapatite bone substitutes are implanted in human bodies, bone tissues will grow into their porous structure, which will reinforce their strength and stiffness. The concept of mechanical com-patibility of bone substitutes implies that their mechanical properties are similar to the bone tissues around, as if they were part of the bone. The mechanical compatibility of bone substitutes includes both static and dynamic behavior, due to the mechanical properties of bone depending on the strain rate. In this study, split Hopkinson pressure bar technique (SHPB) was employed to determine the dy-namic mechanical properties of coralline hydroxyapatite, bones with and bones without organic com-ponents, and their dynamic stress-strain curves of the three materials were obtained. The mechanical effects of collagens in bone were assessed, by comparing the difference between the Young's moduli of the three materials. As the implanted bone substitute becomes a part of bone, it can be regarded as an inclusion composite. The effective modulus of the composite was also evaluated in order to estimate its mechanical compatibility on stiffness. The evaluated result shows that the suitable porosity of HA is0.8, which is in favor of both static and dynamic stiffness compatibility.

  15. Stiffness compatibility of coralline hydroxyapatite bone substitute under dynamic loading

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    When hydroxyapatite bone substitutes are implanted in human bodies,bone tissues will grow into their porous structure,which will reinforce their strength and stiffness.The concept of mechanical com-patibility of bone substitutes implies that their mechanical properties are similar to the bone tissues around,as if they were part of the bone.The mechanical compatibility of bone substitutes includes both static and dynamic behavior,due to the mechanical properties of bone depending on the strain rate.In this study,split Hopkinson pressure bar technique(SHPB) was employed to determine the dy-namic mechanical properties of coralline hydroxyapatite,bones with and bones without organic com-ponents,and their dynamic stress-strain curves of the three materials were obtained.The mechanical effects of collagens in bone were assessed,by comparing the difference between the Young’s moduli of the three materials.As the implanted bone substitute becomes a part of bone,it can be regarded as an inclusion composite.The effective modulus of the composite was also evaluated in order to estimate its mechanical compatibility on stiffness.The evaluated result shows that the suitable porosity of HA is 0.8,which is in favor of both static and dynamic stiffness compatibility.

  16. [Isokinetic assessment of ankles in patients with rheumatoid arthritis].

    Science.gov (United States)

    Oliveira, Silvia Cristina Gutierrez; Oliveira, Leda Magalhaes; Jones, Anamaria; Natour, Jamil

    2015-01-01

    The foot and ankle in rheumatoid arthritis undergo highly destructive synovitis with loss of muscle strength. To evaluate the muscle strength of ankles in patients with rheumatoid arthritis based on isokinetic dynamometry parameters. Thirty patients with a diagnosis of rheumatoid arthritis involving the ankle(s) and 30 healthy subjects (control group) matched for age, gender, race, body mass index and lower limb dominance were studied. Dorsiflexion, plantarflexion, inversion and eversion were evaluated in all subjects on an isokinetic Cybex Norm dynamometer. The variables were compared between the rheumatoid arthritis and control groups and between the right and left ankles, and the dorsiflexor/plantar flexor and invertor/evertor muscle strength ratio was determined. Patients with rheumatoid arthritis performed statistically worse in the isokinetic dynamometry test for all ankle movements. The muscle strength ratio between dorsiflexors and plantar flexors was different in the two groups. No significant differences were observed in the invertor and evertor ratios. In the two groups the plantar flexor musculature was statistically stronger than dorsiflexors. We conclude that patients with rheumatoid arthritis perform worse in isokinetic dynamometry regarding all ankle movements than control subjects, with similar isokinetic test results being observed for the right and left side in both groups, with few exceptions. Isokinetic evaluation posed no additional risk such as important pain or inflammatory activity to patients with rheumatoid arthritis. Copyright © 2014 Elsevier Editora Ltda. All rights reserved.

  17. Influence of distal tibiofibular synostosis on ankle function

    Institute of Scientific and Technical Information of China (English)

    HOU Zhen-hai; ZHOU Ji-hong; YE Hong; SHI Jian-guo; ZHENG Long-bao; YAO Jun; NI Zhi-ming

    2009-01-01

    Objective: To study the influence distal tibiofibular synostosis on ankle function.Methods: From October 1998 to October 2004,a total of 281 consecutive patients underwent operations because of ankle fractures or distal fractures of the tibia and fibula.Distal tibiofibular synostosis occurred after operation in 8 Patients.The duration of follow-up averaged 20.6 months (14-44 months).The ankle function was assessed on the basis of functional rating system described by Mazur.1Results: According to Mazur's ankle evaluation system,4 patients achieved an excellent result,2 a good result and 2 a fair result.The dorsiflexion of the synostosis ankle reduced by 8.26 degrees as compared with that of the contralateral ankle.and there was little influence on the plantar flexion.All the Patients had a normal gait.Conclusion: The distal tibiofibular synostosis after the operation of ankle fractures or distal fractures of the tibia and fibula usually gives rise to few symptoms and needs no specific treatment.

  18. Mobile-bearing total ankle arthroplasty : a fundamental assessment of the clinical, radiographic and functional outcomes

    NARCIS (Netherlands)

    Doets, Hendrik Cornelis

    2009-01-01

    Ankle arthritis often leads to significant impairments for the patient. As total ankle arthroplasty (TAA) with use of fixed-bearing (2-component) total ankle prostheses has a high rate of early failures, fusion of the ankle joint is, until today, considered to be the standard surgical treatment for

  19. Three-dimensional volume rendering of the ankle based on magnetic resonance images enables the generation of images comparable to real anatomy

    Science.gov (United States)

    Anastasi, Giuseppe; Cutroneo, Giuseppina; Bruschetta, Daniele; Trimarchi, Fabio; Ielitro, Giuseppe; Cammaroto, Simona; Duca, Antonio; Bramanti, Placido; Favaloro, Angelo; Vaccarino, Gianluigi; Milardi, Demetrio

    2009-01-01

    We have applied high-quality medical imaging techniques to study the structure of the human ankle. Direct volume rendering, using specific algorithms, transforms conventional two-dimensional (2D) magnetic resonance image (MRI) series into 3D volume datasets. This tool allows high-definition visualization of single or multiple structures for diagnostic, research, and teaching purposes. No other image reformatting technique so accurately highlights each anatomic relationship and preserves soft tissue definition. Here, we used this method to study the structure of the human ankle to analyze tendon–bone–muscle relationships. We compared ankle MRI and computerized tomography (CT) images from 17 healthy volunteers, aged 18–30 years (mean 23 years). An additional subject had a partial rupture of the Achilles tendon. The MRI images demonstrated superiority in overall quality of detail compared to the CT images. The MRI series accurately rendered soft tissue and bone in simultaneous image acquisition, whereas CT required several window-reformatting algorithms, with loss of image data quality. We obtained high-quality digital images of the human ankle that were sufficiently accurate for surgical and clinical intervention planning, as well as for teaching human anatomy. Our approach demonstrates that complex anatomical structures such as the ankle, which is rich in articular facets and ligaments, can be easily studied non-invasively using MRI data. PMID:19678857

  20. Registry data trends of total ankle replacement use.

    Science.gov (United States)

    Roukis, Thomas S; Prissel, Mark A

    2013-01-01

    Joint arthroplasty registry data are meaningful when evaluating the outcomes of total joint replacement, because they provide unbiased objective information regarding survivorship and incidence of use. Critical evaluation of the registry data information will benefit the surgeon, patient, and industry. However, the implementation and acceptance of registry data for total ankle replacement has lagged behind that of hip and knee implant arthroplasty. Currently, several countries have national joint arthroplasty registries, with only some procuring information for total ankle replacement. We performed an electronic search to identify publications and worldwide registry databanks with pertinent information specific to total ankle replacement to determine the type of prostheses used and usage trends over time. We identified worldwide registry data from 33 countries, with details pertinent to total ankle replacement identified in only 6 countries. The obtained information was arbitrarily stratified into 3 distinct periods: 2000 to 2006, 2007 to 2010, and 2011. Within these study periods, the data from 13 total ankle replacement systems involving 3,980 ankles were identified. The vast majority (97%) of the reported ankle replacements were 3-component, mobile-bearing, uncemented prostheses. Three usage trends were identified: initial robust embracement followed by abrupt disuse, minimal use, and initial embracement followed by sustained growth in implantation. Before the widespread acceptance of new total ankle replacements, the United States should scrutinize and learn from the international registry data and develop its own national joint registry that would include total ankle replacement. Caution against the adoption of newly released prostheses, especially those without readily available revision components, is recommended.

  1. Preoperative gait characterization of patients with ankle arthrosis.

    Science.gov (United States)

    Khazzam, Michael; Long, Jason T; Marks, Richard M; Harris, Gerald F

    2006-08-01

    The purpose of this study was to evaluate the kinematic changes that occur about the foot and ankle during gait in patients with degenerative joint disease (DJD). By comparing a normal adult population with what was found in the DJD population we determined how the motion of theses groups differed, thereby characterizing how this pathology affects foot and ankle motion. A 15-camera Vicon Motion Analysis System was used in conjunction with weight bearing radiographs to obtain three-dimensional motion of the foot and ankle during ambulation. The study was comprised of 34 patients and 35 ankles diagnosed with DJD (19 men and 15 women) of the ankle and 25 patients with normal ankles (13 men and 12 women). Dynamic foot and ankle motion was analyzed using the four-segment Milwaukee Foot Model (MFM). The data from this model resulted in three-dimensional (3D) kinematic parameters in the sagittal, coronal, and transverse planes as well as spatial-temporal parameters. Patient health status was evaluated using the SF-36 Health Survey and American Orthopaedics Foot and Ankle Society (AOFAS) hindfoot scores. The DJD group showed significant differences (pgait. This decreased range of motion may be related to several factors including bony deformity, muscle weakness, and attempts to decrease the pain associated with weight bearing. To date there has not been a study which describes the effect of this disease process on motion of the foot and ankle. These findings may prove to be useful in the pre-operative assessment of these patients.

  2. Study on ankle rehabilitation force measuring device%踝关节康复受力测量装置研究

    Institute of Scientific and Technical Information of China (English)

    段学习; 王蕴岭; 汪琦

    2011-01-01

    According to the requirements for ankle rehabilitation, based on biomedical knowledge and institutional knowledge, the equivalent of open serial kinematic chain model of human foot bionic body is built. An ankle rehabilitation device is designed to get the force of ankle rehabilitation indirectly by static analysis of integrated model and change of the plantar force to ankle rehabilitation coordinate system. The rehabilitation equipment with ankle rehabilitation force measuring device can improve the effect of ankle rehabilitation and shorten the recovery time.%针对踝关节康复要求,基于生物医学知识和机构学知识提出串联运动链等效人体足仿生机构模型.设计开发出一种踝关节受力测量装置,将患者在康复过程中的足底受力折算到踝关节坐标系,间接得到患者踝关节康复受力值,可作为医护人员指导患者控制康复运动强度的参照数据.实验表明安装踝关节康复受力测量装置的康复器械提高了踝关节的康复效果,有效缩短了康复周期,降低了二次损伤的几率.

  3. The stable stiffness triangle - drained sand during deformation cycles

    DEFF Research Database (Denmark)

    Sabaliauskas, Tomas; Ibsen, Lars Bo

    2017-01-01

    Cyclic, drained sand stiffness was observed using the Danish triaxial appa- ratus. New, deformation dependant soil property (the stable stiffness triangle) was detected. Using the the stable stiffness triangle, secant stiffness of drained sand was plausible to predict (and control) even during ir...

  4. Use of a trabecular metal implant in ankle arthrodesis after failed total ankle replacement

    Science.gov (United States)

    2010-01-01

    Background and purpose Arthrodesis after failed total ankle replacement is complicated and delayed union, nonunion, and shortening of the leg often occur—especially with large bone defects. We investigated the use of a trabecular metal implant and a retrograde intramedullary nail to obtain fusion. Patients and methods 13 patients with a migrated or loose total ankle implant underwent arthrodesis with the use of a retrograde intramedullary nail through a trabecular metal Tibial Cone. The mean follow-up time was 1.4 (0.6–3.4) years. Results At the last examination, 7 patients were pain-free, while 5 had some residual pain but were satisfied with the procedure. 1 patient was dissatisfied and experienced pain and swelling when walking. The implant-bone interfaces showed no radiographic zones or gaps in any patient, indicating union. Interpretation The method is a new way of simplifying and overcoming some of the problems of performing arthrodesis after failed total ankle replacement. PMID:21067435

  5. Outcome of unilateral ankle arthrodesis and total ankle replacement in terms of bilateral gait mechanics.

    Science.gov (United States)

    Chopra, Swati; Rouhani, Hossein; Assal, Mathieu; Aminian, Kamiar; Crevoisier, Xavier

    2014-03-01

    Previous studies assessed the outcome of ankle arthrodesis (AA) and total ankle replacement (TAR) surgeries; however, the extent of postoperative recovery towards bilateral gait mechanics (BGM) is unknown. We evaluated the outcome of the two surgeries at least 2 years post rehabilitation, focusing on BGM. 36 participants, including 12 AA patients, 12 TAR patients, and 12 controls were included. Gait assessment over 50 m distance was performed utilizing pressure insoles and 3D inertial sensors, following which an intraindividual comparison was performed. Most spatiotemporal and kinematic parameters in the TAR group were indicative of good gait symmetry, while the AA group presented significant differences. Plantar pressure symmetry among the AA group was also significantly distorted. Abnormality in biomechanical behavior of the AA unoperated, contralateral foot was observed. In summary, our results indicate an altered BGM in AA patients, whereas a relatively fully recovered BGM is observed in TAR patients, despite the quantitative differences in several parameters when compared to a healthy population. Our study supports a biomechanical assessment and rehabilitation of both operated and unoperated sides after major surgeries for ankle osteoarthrosis.

  6. Genetically elevated levels of circulating triglycerides and brachial-ankle pulse wave velocity in a Chinese population.

    Science.gov (United States)

    Yao, W-M; Zhang, H-F; Zhu, Z-Y; Zhou, Y-L; Liang, N-X; Xu, D-J; Zhou, F; Sheng, Y-H; Yang, R; Gong, L; Yin, Z-J; Chen, F-K; Cao, K-J; Li, X-L

    2013-04-01

    Elevated levels of circulating triglycerides and increased arterial stiffness are associated with cardiovascular disease. Numerous studies have reported an association between levels of circulating triglycerides and arterial stiffness. We used Mendelian randomization to test whether this association is causal. We investigated the association between circulating triglyceride levels, the apolipoprotein A-V (ApoA5) -1131T>C single nucleotide polymorphism and brachial-ankle pulse wave velocity (baPWV) by examining data from 4421 subjects aged 18-74 years who were recruited from the Chinese population. baPWV was significantly associated with the levels of circulating triglycerides after adjusting for age, sex, body mass index (BMI), systolic blood pressure, heart rate, waist-to-hip ratio, antihypertensive treatment and diabetes mellitus status. The -1131C allele was associated with a 5% (95% confidence interval 3-8%) increase in circulating triglycerides (adjusted for age, sex, BMI, waist-to-hip ratio, diabetes mellitus and antihypertensive treatment). Instrumental variable analysis showed that genetically elevated levels of circulating triglycerides were not associated with increased baPWV. These results do not support the hypothesis that levels of circulating triglycerides have a causal role in the development of arterial stiffness.

  7. Agility to INBONE: anterior and posterior approaches to the difficult revision total ankle replacement.

    Science.gov (United States)

    DeVries, J George; Scott, Ryan T; Berlet, Gregory C; Hyer, Christopher F; Lee, Thomas H; DeOrio, James K

    2013-01-01

    Total ankle replacement is now acknowledged as a viable alternative to ankle arthrodesis for end-stage ankle arthritis. The authors present a series of 14 patients who were converted from the Agility total ankle replacement to an INBONE total ankle replacement. This report is unique in that anterior and posterior approaches are discussed and detailed. Although the authors present successful conversion of the Agility total ankle replacement to an INBONE total ankle replacement, the difficulty of this procedure is demonstrated by the high complication rate and 2 early failures.

  8. Strategies for Revision Total Ankle Replacement

    Directory of Open Access Journals (Sweden)

    Thomas S. Roukis, DPM, PhD, FACFAS

    2014-12-01

    Full Text Available As the frequency of primary total ankle replacement (TAR continues to build, revision will become more commonplace. At present there are no “standard principles” associated with revision TAR. What is clear is that the current approaches are technically complex, fraught with complications and no one approach represents the only answer. Exchange of TAR metallic components to the same system standard or dedicated revision components are viable options with limited occurrence of complications. Explantation and conversion to custom-design long stemmed components has limited availability. Explantation and conversion to another TAR system is high-risk and has strong potential for complications. The use of metal reinforced polymethylmethacrylate cement augmentation of failed TAR systems and tibio-talo-calcaneal arthrodesis should be reserved for very select situations where other options are not possible. There is a real need for long-term survivorship following revision TAR and future efforts ought to be directed in this area.

  9. Waves in geomaterials exhibiting negative stiffness behaviour

    Science.gov (United States)

    Esin, Maxim; Dyskin, Arcady; Pasternak, Elena

    2016-04-01

    Negative stiffness denotes the type of material behaviour when the force applied to the body decreases the body's deformation increases. Some geomaterials, for instance, rocks, demonstrate behaviour of this type at certain loads: during the compression tests the loading curves exhibit descending branch (post-peak softening). One of the possible mechanisms of the negative stiffness appearance in geomaterials is rotation of non-spherical grains. It is important to emphasize that in this case the descending branch may be reversible given that the testing machine is stiff enough (in general case it means an importance of boundary conditions). Existence of geomaterials with a negative modulus associated with rotations may have significant importance. In particular, important is understanding of the wave propagation in such materials. We study the stability of geomaterials with negative stiffness inclusions and wave propagation in it using two approaches: Cosserat continuum and discrete mass-spring models. In both cases we consider the rotational degrees of freedom in addition to the conventional translational ones. We show that despite non positiveness of the energy the materials with negative stiffness elements can be stable if certain conditions are met. In the case of Cosserat continuum the Cosserat shear modulus (the modulus relating the non-symmetrical part of shear stress and internal rotations) is allowed to assume negative values as long as its value does not exceed the value of the standard (positive) shear modulus. In the case of discrete mass-spring systems (with translational and rotational springs) the concentration of negative stiffness springs and the absolute values of negative spring stiffness are limited. The critical concentration when the system loses stability and the amplitude of the oscillations tends to infinity is equal to 1/2 and 3/5 for two- and three-dimensional cases respectively.

  10. Multicenter follow-up study of ankle fracture surgery

    Institute of Scientific and Technical Information of China (English)

    XU Hai-lin; WANG Gang; WANG Guang-lin; WU Xin-bao; LIU Li-min; LI Xuan; ZHANG Dian-ying; FU Zhong-guo; WANG Tian-bing; ZHANG Pei-xun; JIANG Bao-guo; SHEN Hui-liang

    2012-01-01

    Background Few data on ankle fractures in China from large multicenter epidemiological and clinical studies are available.The aim of this research was to evaluate the epidemiological features and surgical outcomes of ankle fractures by reviewing 235 patients who underwent ankle fracture surgery at five hospitals in China.Methods This study included patients who underwent ankle fracture surgery at five Chinese hospitals from January 2000 to July 2009.Age,gender,mechanism of injury,Arbeitsgemeinschaft für Osteosynthesefragen (AO) fracture type,fracture pattern,length of hospital stay and treatment outcome were recorded.Statistical analyses were conducted using SPSS software.The American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale,visual analogue scale (VAS),and arthritis scale were used to evaluate outcome.Results Of 235 patients with ankle fractures,105 were male with an average age of 37.8 years and 130 were female with an average age of 47.3 years.The average follow-up period was 55.7 months.There were significant differences in the ratios of patients in different age groups between males and females,and in mechanisms of injury among different age groups.There were also significant differences in the length of hospital stay among different fracture types and mechanisms of injury.In healed fractures,the average AOFAS ankle-hindfoot score was 95.5,with an excellence rate of 99.6%,the average VAS score was 0.17,and the average arthritis score was 0.18.Movement of the injured ankle was significantly different to that of the uninjured ankle.There were no significant differences between AO fracture types,fracture patterns or follow-up periods and AOFAS score,but there were some significant differences between these parameters and ankle joint movements,pain VAS score and arthritis score.Conclusions Ankle fractures occur most commonly in middle-aged and young males aged 20-39 years and in elderly females aged 50-69 years.The most common mechanisms of

  11. Early intra-articular complement activation in ankle fractures

    DEFF Research Database (Denmark)

    Schmal, Hagen; Salzmann, Gian M; Niemeyer, Philipp;

    2014-01-01

    osteochondritis dissecans (OCD) of the ankle. All fractures needed external fixation during which joint effusions were collected. Fluid analysis was done by ELISA measuring aggrecan, bFGF, IL-1 β, IGF-1, and the complement components C3a, C5a, and C5b-9. The time periods between occurrence of fracture...... and OCD patients, bFGF, IGF-1, and all complement components were significantly higher concentrated in ankle joints with fractures (P Complement activation and inflammatory cell infiltration characterize the joint biology following acute ankle fractures....

  12. Review of ankle inversion sprain simulators in the biomechanics laboratory

    Directory of Open Access Journals (Sweden)

    Sophia Chui-Wai Ha

    2015-10-01

    Full Text Available Ankle inversion ligamentous sprain is one of the most common sports injuries. The most direct way is to investigate real injury incidents, but it is unethical and impossible to replicate on test participants. Simulators including tilt platforms, trapdoors, and fulcrum devices were designed to mimic ankle inversion movements in laboratories. Inversion angle was the only element considered in early designs; however, an ankle sprain is composed of inversion and plantarflexion in clinical observations. Inversion velocity is another parameter that increased the reality of simulation. This review summarised the simulators, and aimed to compare and contrast their features and settings.

  13. Seasonality of Ankle Swelling: Population Symptom Reporting Using Google Trends.

    Science.gov (United States)

    Liu, Fangwei; Allan, G Michael; Korownyk, Christina; Kolber, Michael; Flook, Nigel; Sternberg, Harvey; Garrison, Scott

    2016-07-01

    In our experience, complaints of ankle swelling are more common in summer, typically from patients with no obvious cardiovascular disease. Surprisingly, this observation has never been reported. To objectively establish this phenomenon, we sought evidence of seasonality in the public's Internet searches for ankle swelling. Our data, obtained from Google Trends, consisted of all related Google searches in the United States from January 4, 2004, to January 26, 2016. Consistent with our expectations and confirmed by similar data for Australia, Internet searches for information on ankle swelling are highly seasonal (highest in midsummer), with seasonality explaining 86% of search volume variability.

  14. Diabetic charcot neuroarthropathy of the foot and ankle with osteomyelitis.

    Science.gov (United States)

    Ramanujam, Crystal L; Stapleton, John J; Zgonis, Thomas

    2014-10-01

    One of the most devastating foot and/or ankle complications in the diabetic population with peripheral neuropathy is the presence of Charcot neuroarthropathy (CN). In recent years, diabetic limb salvage has been attempted more frequently as opposed to major lower extremity amputation for CN of the foot and ankle with ulceration and/or deep infection. Treatment strategies for osteomyelitis in the diabetic population have evolved. This article reviews some of the most common surgical strategies recommended for the diabetic patient with CN of the foot and/or ankle and concomitant osteomyelitis.

  15. Internal Fixation of Open Ankle Fracture. Report of Two Cases

    Directory of Open Access Journals (Sweden)

    Yaniel Truffin Rodríguez

    2014-10-01

    Full Text Available Open ankle fracture is sporadically seen in the orthopedic practice. Its clinical course is subject to multiple factors, showing a propensity to cause ankle osteoarthritis over the years. Two cases treated at the Dr. Gustavo Aldereguía Lima University General Hospital in Cienfuegos are presented. The patients underwent emergency surgical treatment consisting of surgical cleaning of the open wound, reduction of the dislocation and internal fixation of the fracture. These cases are presented due to the infrequency of this type of ankle injury and its importance for the medical staff, especially orthopedic doctors.

  16. Ultrasound-guided interventions of the foot and ankle.

    Science.gov (United States)

    Yablon, Corrie M

    2013-02-01

    Ultrasound (US) provides excellent delineation of tendons and ligaments in the foot and ankle and provides real-time visualization of a needle during interventions, yielding greater accuracy and efficacy than the traditional blind approach using anatomical landmarks. For this reason, US is rapidly gaining acceptance as the preferred modality for guiding interventions in the foot and ankle where the anatomy is complex, neurovascular structures should be identified, and precise technique is demanded. In the foot and ankle, US is especially useful to guide tendon sheath, bursal, and Achilles paratenon injections, Morton neuroma injections, plantar fascial injections, and joint aspirations and injections.

  17. Bipolar fresh osteochondral allograft of the ankle.

    Science.gov (United States)

    Giannini, Sandro; Buda, Roberto; Grigolo, Brunella; Bevoni, Roberto; Di Caprio, Francesco; Ruffilli, Alberto; Cavallo, Marco; Desando, Giovanna; Vannini, Francesca

    2010-01-01

    Severe post-traumatic ankle arthritis poses a reconstructive challenge in the young and active patient. Bipolar fresh osteochondral allograft (BFOA) may represent an intriguing alternative to arthrodesis and prosthetic replacement. The aim of this study was to describe a lateral trans-malleolar technique for BFOA, and to evaluate the results in a case series. From 2004 to 2006, 32 patients, mean age of 36.8 +/- 8.4 years, affected by ankle arthritis underwent BFOA with a mean followup of 31.2 months. The graft was prepared by specifically designed jigs, including the talus and the tibia with the medial malleolus. The host surfaces were prepared by the same jigs through a lateral approach. The graft was placed and fixed with twist-off screws. Patients were evaluated clinically and radiographically at 2, 4, and 6 month after operation, and at a minimum 24 months followup. A biopsy of the grafted areas was obtained from 7 patients at 1-year followup for histological and immunohistochemical examination. Preoperative AOFAS score was 33.1 +/- 10.9 and postoperatively 69.5 +/- 19.4 (p < 0.0005). Six failures occurred. Cartilage harvests showed hyaline-like histology with a normal collagen component but low proteoglycan presence and a disorganized structure. Samples were positive for MMP-1, MMP-13 and Capsase-3. The use of BFOA represents an intriguing alternative to arthrodesis or arthroplasty. We believe precise allograft sizing, stable fitting and fixation and delayed weightbearing were key factors for a successful outcome. Further research regarding the immunological behavior of transplanted cartilage is needed.

  18. Optimal management of ankle syndesmosis injuries

    Directory of Open Access Journals (Sweden)

    Porter DA

    2014-08-01

    Full Text Available David A Porter, Ryan R Jaggers, Adam Fitzgerald Barnes, Angela M Rund Methodist Sports Medicine/The Orthopedic Specialists, Indianapolis, IN, USA Abstract: Syndesmosis injuries occur when there is a disruption of the distal attachment of the tibia and fibula. These injuries occur commonly (up to 18% of ankle sprains, and the incidence increases in the setting of athletic activity. Recognition of these injuries is key to preventing long-term morbidity. Diagnosis and treatment of these injuries requires a thorough understanding of the normal anatomy and the role it plays in the stability of the ankle. A complete history and physical examination is of paramount importance. Patients usually experience an external rotation mechanism of injury. Key physical exam features include detailed documentation about areas of focal tenderness (syndesmosis and deltoid and provocative maneuvers such as the external rotation stress test. Imaging workup in all cases should consist of radiographs with the physiologic stress of weight bearing. If these images are inconclusive, then further imaging with external rotation stress testing or magnetic resonance imaging are warranted. Nonoperative treatment is appropriate for stable injuries. Unstable injuries should be treated operatively. This consists of stabilizing the syndesmosis with either trans-syndesmotic screw or tightrope fixation. In the setting of a concomitant Weber B or C fracture, the fibula is anatomically reduced and stabilized with a standard plate and screw construct. Proximal fibular fractures, as seen in the Maisonneuve fracture pattern, are not repaired operatively. Recent interest is moving toward repair of the deltoid ligament, which may provide increased stability, especially in rehabilitation protocols that involve early weight bearing. Rehabilitation is focused on allowing patients to return to their pre-injury activities as quickly and safely as possible. Protocols initially focus on

  19. Optimal management of ankle syndesmosis injuries.

    Science.gov (United States)

    Porter, David A; Jaggers, Ryan R; Barnes, Adam Fitzgerald; Rund, Angela M

    2014-01-01

    Syndesmosis injuries occur when there is a disruption of the distal attachment of the tibia and fibula. These injuries occur commonly (up to 18% of ankle sprains), and the incidence increases in the setting of athletic activity. Recognition of these injuries is key to preventing long-term morbidity. Diagnosis and treatment of these injuries requires a thorough understanding of the normal anatomy and the role it plays in the stability of the ankle. A complete history and physical examination is of paramount importance. Patients usually experience an external rotation mechanism of injury. Key physical exam features include detailed documentation about areas of focal tenderness (syndesmosis and deltoid) and provocative maneuvers such as the external rotation stress test. Imaging workup in all cases should consist of radiographs with the physiologic stress of weight bearing. If these images are inconclusive, then further imaging with external rotation stress testing or magnetic resonance imaging are warranted. Nonoperative treatment is appropriate for stable injuries. Unstable injuries should be treated operatively. This consists of stabilizing the syndesmosis with either trans-syndesmotic screw or tightrope fixation. In the setting of a concomitant Weber B or C fracture, the fibula is anatomically reduced and stabilized with a standard plate and screw construct. Proximal fibular fractures, as seen in the Maisonneuve fracture pattern, are not repaired operatively. Recent interest is moving toward repair of the deltoid ligament, which may provide increased stability, especially in rehabilitation protocols that involve early weight bearing. Rehabilitation is focused on allowing patients to return to their pre-injury activities as quickly and safely as possible. Protocols initially focus on controlling swelling and recovery from surgery. The protocols then progress to restoration of motion, early protected weight bearing, restoration of strength, and eventually a

  20. Variable stiffness design of redundantly actuated planar rotational parallel mechanisms

    Institute of Scientific and Technical Information of China (English)

    Li Kangkang; Jiang Hongzhou; Cui Zuo; Huang Qun

    2017-01-01

    Redundantly actuated planar rotational parallel mechanisms (RAPRPMs) adapt to the requirements of robots under different working conditions by changing the antagonistic internal force to tune their stiffness. The geometrical parameters of the mechanism impact the performances of modulating stiffness. Analytical expressions relating stiffness and geometrical parameters of the mechanism were formulated to obtain the necessary conditions of variable stiffness. A novel method of variable stiffness design was presented to optimize the geometrical parameters of the mechanism. The stiffness variation with the internal force was maximized. The dynamic change of