Sample records for stress fractures result

  1. Spallation and fracture resulting from reflected and intersecting stress waves.

    Kinslow, R.


    Discussion of the effects of stress waves produced in solid by explosions or high-velocity impacts. These waves rebound from free surfaces in the form of tensile waves that are capable of causing internal fractures or spallation of the material. The high-speed framing camera is shown to be an important tool for observing the stress waves and fracture in transparent targets, and its photographs provide valuable information on the mechanics of fracture.

  2. Stress Fractures

    Stress fractures Overview Stress fractures are tiny cracks in a bone. They're caused by repetitive force, often from overuse — such as repeatedly jumping up and down or running long distances. Stress fractures can also arise from normal use of ...

  3. Metatarsal stress fractures - aftercare

    ... page: // Metatarsal stress fractures - aftercare To use the sharing features on ... that connect your ankle to your toes. A stress fracture is a break in the bone that ...


    Đivo Ban


    Full Text Available Children and adolescents today, all before starting with regular sports activities and involvement in semi-professional and top professional sport, so it increases the num- ber of discovered stress fractures in this age. This type of injury can occur as a consequence of action one strong force, or the many repeated small force strength, to be exact, when the load (stress transcend ability reparations bones. Stress fractures are recorded and described up to the lower limbs. Research has been confirmed that the bones of lower leg are mostly made in injury, and with the el- derly and with the population of children and young adolescents. Occur in many sports, something to them is greater when the frequency of running and often are present in the female population. According to the results of numerous investigations, mistakes in the training are the most common cause of the emergence of stress fracture. In a direct comparison with complemented these injuries is the condition of muscles, so it is important that at the sa- me time carry out exercises strengthen muscles and stretching. Typical clinical signs of stress fractures are localized painful sensitivity to palpa- tion and runoff in a small number of cases. The basic diagnostic procedure is a medical check, it is the small, radiology and scintigraphyc diagnostics (most accurate and mag- netic resonance imaging. Treatment is usually without surgery and conservative, with rest and reducing stress, and its activity athlete breaks mainly between four and eight weeks. Only the very need surgical treatment The most important thing is that attention is focused on the proper prevention and to take all that it ever occurred to stress fractures that athletes ramble of the courts and the competition (better education of sports workers, separation of groups with increa- sed risk of the formation of an injury, adaptation activities age and abilities of athletes, adequate sports equipment, high-quality sports

  5. Stress fractures in runners.

    McCormick, Frank; Nwachukwu, Benedict U; Provencher, Matthew T


    Stress fractures are a relatively common entity in athletes, in particular, runners. Physicians and health care providers should maintain a high index of suspicion for stress fractures in runners presenting with insidious onset of focal bone tenderness associated with recent changes in training intensity or regimen. It is particularly important to recognize “high-risk” fractures, as these are associated with an increased risk of complication. A patient with confirmed radiographic evidence of a high-risk stress fracture should be evaluated by an orthopedic surgeon. Runners may benefit from orthotics, cushioned sneakers, interval training, and vitamin/calcium supplementation as a means of stress fracture prevention.

  6. FAST TRACK PAPER: The creation of an asymmetric hydraulic fracture as a result of driving stress gradients

    Fischer, T.; Hainzl, S.; Dahm, T.


    Hydraulic fracture stimulation is frequently performed in hydrocarbon reservoirs and geothermal systems to increase the permeability of the rock formation. These hydraulic fractures are often mapped by hypocentres of induced microearthquakes. In some cases microseismicity exhibits asymmetry relative to the injection well, which can be interpreted by unequal conditions for fracture growth at opposite sides of the well or by observation effects. Here we investigate the role of the lateral change of the minimum compressive stress. We use a simple model to describe the relation among the lateral stress gradient, the mean viscous pressure gradients in the fracture wings, the fracture geometry, and the net pressure in the fracture. Our model predicts a faster fracture growth in the direction of decreasing stress and a limited growth in the opposite direction. We derive a simple relationship to estimate the lateral stress gradient from the injection pressure and the shape of the seismic hypocentre cloud. The model is tested by microseismic data obtained during stimulation of a Canyon Sands gas field in West Texas. Using a maximum likelihood method we fit the parameters of the asymmetric fracture model to the space-time pattern of hypocentres. The estimated stress gradients per metre are in the range from 0.008 to 0.010 times the bottom-hole injection overpressure (8-10 kPam-1 assuming the net pressure of 1 MPa). Such large horizontal gradients in the order of the hydrostatic gradient could be caused by the inhomogeneous extraction of gas resulting in a lateral change of the effective normal stress acting normal to the fracture wall.

  7. Anisotropic stress accumulation in cooling lava flows and resulting fracture patterns: Insights from starch-water desiccation experiments

    Lodge, Robert W. D.; Lescinsky, David T.


    Desiccation of starch-water slurries is a useful analog for the production of polygonal fractures/columnar joints in cooling lava flows. When left to dry completely, a simple mixture of 1:1 starch and water will produce columns that appear remarkably similar to natural columnar joints formed in cooled lava flows. Columns form when the accumulation of isotropic stress exceeds the tensile strength of a material, at which point a fracture forms and advances through the material perpendicular to the desiccating surface. Individual fractures will initially form orthogonal to the desiccation surface but will quickly evolve into a hexagonal fracture network that advances incrementally through the material. However, some fracture patterns found within natural lava flows are not hexagonal ( Lodge and Lescinsky, 2009-this issue), but rather have fracture lengths that are much longer than the distance to adjacent fractures. These fractures are commonly found at lava flows that have interacted with glacial ice during emplacement. The purpose of this study is to utilize starch analog experiments to better understand the formation of these fractures and the stress regimes responsible for their non-hexagonal patterns. To simulate anisotropic conditions during cooling, the starch slurry was poured into a container with a movable wall that was attached to a screw-type jack. The jack was then set to slowly extend or retract while the slurry desiccated. This resulted in either a decrease or increase in the chamber cross-sectional area thus creating compressional or extensional regimes. Decreasing chamber area (DCA) experiments resulted in fractures with larger lengths parallel to the direction of wall movement (also direction of compression). It also caused localized thrust faulting and curved column development. Increasing chamber area (ICA) experiments produced a zone of horizontal column development along the expanding margin (produced when the wall detached from the sample

  8. Interpretation of stress damage on fracture conductivity

    Berumen, Sergio; Tiab, Djebbar [PEMEX E and P and The University of Oklahoma, School of Petroleum and Geological Engineering, Norman, OK (United States)


    This paper focuses on the investigation of pressure responses in a well producing through a composite system of a stress-sensitive vertical symmetric or asymmetric fracture interacting with a stress-sensitive permeable-porous medium. Results of this investigation demonstrate that when the fracture conductivity is stress dependent, the use of conventional techniques to evaluate fractured wells may lead to incorrect estimates of the fracture-formation properties. For finite conductivity fractures, the stress effects in the formation have a negligible influence on the absolute value of the slope that defines the pseudo-bilinear flow regime. During this flow regime only the pressure sensitivity in the fracture and the fracture conductivity govern this flow period. For cases that involve highly conductive fractures, it was found that the slope of 0.5 which defines the linear flow regime is not influenced by the stress effect of the fracture and formation. However, stress in highly conductive fractures has a measurable influence in the change of conductivity. The occurrence of the stress damage in finite and infinite conductivity fractures is due to the partial closure fracture or partial choke fracture effect and can be anticipated in terms of pressure or time level by using the equations provided in this work. The results derived from this research have a major impact in improving the analysis of fractured wells pressure responses, as well as in forecasting of fracture closure occurrence and in programming stimulation operations in fractured wells. An example with synthetic data is presented to illustrate these new findings

  9. Stress fractures in the lower extremity

    Berger, Ferco H. [Academic Medical Center, University of Amsterdam, Department of Radiology, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Jonge, Milko C. de [Academic Medical Center, University of Amsterdam, Department of Radiology, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands); Maas, Mario [Academic Medical Center, University of Amsterdam, Department of Radiology, Meibergdreef 9, 1105 AZ Amsterdam (Netherlands)]. E-mail:


    Stress fractures are fatigue injuries of bone usually caused by changes in training regimen in the population of military recruits and both professional and recreational athletes. Raised levels of sporting activity in today's population and refined imaging technologies have caused a rise in reported incidence of stress fractures in the past decades, now making up more than 10% of cases in a typical sports medicine practice. Background information (including etiology, epidemiology, clinical presentation and treatment and prevention) as well as state of the art imaging of stress fractures will be discussed to increase awareness amongst radiologists, providing the tools to play an important role in diagnosis and prognosis of stress fractures. Specific fracture sites in the lower extremity will be addressed, covering the far majority of stress fracture incidence. Proper communication between treating physician, physical therapist and radiologist is needed to obtain a high index of suspicion for this easily overlooked entity. Radiographs are not reliable for detection of stress fractures and radiologist should not falsely be comforted by them, which could result in delayed diagnosis and possibly permanent consequences for the patient. Although radiographs are mandatory to rule out differentials, they should be followed through when negative, preferably by magnetic resonance imaging (MRI), as this technique has proven to be superior to bone scintigraphy. CT can be beneficial in a limited number of patients, but should not be used routinely.

  10. Stress fractures: definition, diagnosis and treatment☆

    Astur, Diego Costa; Zanatta, Fernando; Arliani, Gustavo Gonçalves; Moraes, Eduardo Ramalho; Pochini, Alberto de Castro; Ejnisman, Benno


    Stress fractures were first described in Prussian soldiers by Breithaupt in 1855. They occur as the result of repeatedly making the same movement in a specific region, which can lead to fatigue and imbalance between osteoblast and osteoclast activity, thus favoring bone breakage. In addition, when a particular region of the body is used in the wrong way, a stress fracture can occur even without the occurrence of an excessive number of functional cycles. The objective of this study was to review the most relevant literature of recent years in order to add key information regarding this pathological condition, as an updating article on this topic. PMID:26962487

  11. Pedicular stress fracture in the lumbar spine

    Chong, V.F.H.; Htoo, M.M. [Singapore General Hospital, Singapore, (Singapore). Department of Diagnostic Radiology


    Spondylolisthesis with or without spondylolysis is common in the lumbar spine. Associated fracture in the pedicle (`pediculolysis`) is unusual. The margins of pedicular stress fractures, like spondylolysis, usually appear sclerotic. A patient with a pedicular stress fracture with minimal marginal sclerosis suggesting an injury of recent onset is presented here. There was associated bilateral spondylolysis. The findings in this patient suggest that established pediculolysis probably represents a stress fracture that has failed to heal. (authors). 10 refs., 2 figs.

  12. Hydraulic fracture model comparison study: Complete results

    Warpinski, N.R. [Sandia National Labs., Albuquerque, NM (United States); Abou-Sayed, I.S. [Mobil Exploration and Production Services (United States); Moschovidis, Z. [Amoco Production Co. (US); Parker, C. [CONOCO (US)


    Large quantities of natural gas exist in low permeability reservoirs throughout the US. Characteristics of these reservoirs, however, make production difficult and often economic and stimulation is required. Because of the diversity of application, hydraulic fracture design models must be able to account for widely varying rock properties, reservoir properties, in situ stresses, fracturing fluids, and proppant loads. As a result, fracture simulation has emerged as a highly complex endeavor that must be able to describe many different physical processes. The objective of this study was to develop a comparative study of hydraulic-fracture simulators in order to provide stimulation engineers with the necessary information to make rational decisions on the type of models most suited for their needs. This report compares the fracture modeling results of twelve different simulators, some of them run in different modes for eight separate design cases. Comparisons of length, width, height, net pressure, maximum width at the wellbore, average width at the wellbore, and average width in the fracture have been made, both for the final geometry and as a function of time. For the models in this study, differences in fracture length, height and width are often greater than a factor of two. In addition, several comparisons of the same model with different options show a large variability in model output depending upon the options chosen. Two comparisons were made of the same model run by different companies; in both cases the agreement was good. 41 refs., 54 figs., 83 tabs.

  13. Fractures and stresses in Bone Spring sandstones

    Lorenz, J.C.; Warpinski, N.R.; Sattler, A.R.; Northrop, D.A.


    This project is a collaboration between Sandia National Laboratories and Harvey E. Yates Company being conducted under the auspices of the Oil Recovery Technology Partnership. The project seeks to apply perspectives related to the effects of natural fractures, stress, and sedimentology to the simulation and production of low-permeability gas reservoirs to low-permeability oil reservoirs as typified by the Bone Spring sandstones of the Permian Basin, southeast New Mexico. This report presents the results and analysis obtained in 1989 from 233 ft of oriented core, comprehensive suite of logs, various in situ stress measurements, and detailed well tests conducted in conjunction with the drilling of two development wells. Natural fractures were observed in core and logs in the interbed carbonates, but there was no direct evidence of fractures in the sandstones. However, production tests of the sandstones indicated permeabilities and behavior typical of a dual porosity reservoir. A general northeast trend for the maximum principal horizontal stress was observed in an elastic strain recovery measurements and in strikes of drilling-induced fractures; this direction is subparallel to the principal fracture trend observed in the interbed carbonates. Many of the results presented are believed to be new information for the Bone Spring sandstones. 57 figs., 18 tabs.

  14. Impact of Stress on Anomalous Transport in Fractured Rock

    Kang, P. K.; Lei, Q.; Lee, S.; Dentz, M.; Juanes, R.


    Fluid flow and transport in fractured rock controls many natural and engineered processes in the subsurface. However, characterizing flow and transport through fractured media is challenging due to the large heterogeneity of fractured rock properties. In addition to these "static" challenges, geologic fractures are always under significant overburden stress, and changes in the stress state can lead to changes in the fracture's ability to conduct fluids. While confining stress has been shown to impact fluid flow through fractures in a fundamental way, the impact of confining stress on transport through fractured rock remains largely unexplored. The link between anomalous (non-Fickian) transport and confining stress has been shown only recently, at the level of a single rough fracture [1]. Here, we investigate the impact of confining stress on flow and transport through discrete fracture networks. We model geomechanical effects in 2D fractured rock by means of a finite-discrete element method (FEMDEM), which can capture the deformation of matrix blocks, reactivation and propagation of cracks. We implement a joint constitutive model within the FEMDEM framework to simulate the effect of fracture roughness. We apply the model to a fracture network extracted from the geological map of an actual outcrop to obtain the aperture field at different stress conditions (Figure 1). We then simulate fluid flow and particle transport through the stressed fracture networks. We observe that anomalous transport emerges in response to confining stress on the fracture networks, and show that this anomalous behavior can be linked to the stress state of the rock. Finally, we develop an effective transport model that captures the anomalous transport through stressed fractures. Our results point to a heretofore unrecognized link between geomechanics and anomalous transport in discrete fractured networks. [1] P. K. Kang, S. Brown, and R. Juanes, Emergence of anomalous transport in stressed

  15. Female athlete triad and stress fractures.

    Feingold, David; Hame, Sharon L


    Stress fractures are a common occurrence in athletes, and the incidence of stress fractures in female Division 1 collegiate athletes is double that of men. Hormonal influences on bone and bone morphology may influence the risk for fracture. A high level of suspicion and special imaging procedures allow for accurate diagnosis of these fractures. In stress fractures that are associated with the female athlete triad, addressing the three aspects of the triad--eating disorders, amenorrhea, and osteoporosis--are critical for successful treatment. Preparticipation screening for the presence of signs of the female athlete triad by monitoring weight, energy level, menstrual cycles, and bone mineral density may help to prevent the occurrence of stress fractures in this population.


    A.S. Grader; D. Elsworth; P.M. Halleck; F. Alvarado; A. Alajmi; Z. Karpyn; N. Mohammed; S. Al-Enezi


    The main objectives of this project are to quantify the changes in fracture porosity and multiphase transport properties as a function of confining stress. These changes will be integrated into conceptual and numerical models that will improve our ability to predict and optimize fluid transport in fractured system. This report details our progress on: (a) developing the direct experimental measurements of fracture aperture and topology and fluid occupancy using high-resolution x-ray micro-tomography, (b) quantifying the effect of confining stress on the distribution of fracture aperture, and (c) characterization of shear fractures and their impact on multi-phase flow. The three-dimensional surface that describes the large-scale structure of the fracture in the porous medium can be determined using x-ray micro-tomography with significant accuracy. Several fractures have been scanned and the fracture aperture maps have been extracted. The success of the mapping of fracture aperture was followed by measuring the occupancy of the fracture by two immiscible phases, water and decane, and water and kerosene. The distribution of fracture aperture depends on the effective confining stress on the nature of the rock and the type and distribution of the asperities that keep the fracture open. Fracture apertures at different confining stresses were obtained by micro-tomography covering a range of about two thousand psig. Initial analysis of the data shows a significant aperture closure with increase in effective confining stress. Visual descriptions of the process are shown in the report while detailed analysis of the behavior of the distribution of fracture aperture is in progress. Both extensional and shear fractures are being considered. The initial multi-phase flow tests were done in extensional fractures. Several rock samples with induced shear fracture are being studies, and some of the new results are presented in this report. These samples are being scanned in order to

  17. Our Results in Penile Fractures

    Tufan Süelözgen


    Full Text Available Introduction Penile fracture is a urological emergency caused by direct trauma to an erected penis, tearing the tunica albuginea in the corpus cavernosum. The preferred treatment method is draining the hematoma and surgical repair of tunica albuginea tear as soon as possible following diagnosis. Materials and Methods Forty-nine patients who were diagnosed with penile fracture between January 2009 and December 2014 were reviewed. Physical examination was performed to see the extent of penile hematoma, the side of the penile curvature and the presence of blood in the external meatus. Two patients who were diagnosed with urethrorrhagia underwent retrograde urethrogram for urethral injury. In all patients, penile skin was peeled using a circular subcoronal degloving incision and tunica tear was repaired using absorbable suture materials. The patients were then followed for painful erections, penile deformities and erection angles. Results The average age of the 49 patients, who were included in the study, was 36.5 years (21-65. In their etiological questioning, most patients reported the fracture occurring during sexual intercourse. Retrograde urethrography was indicated in 2 patients with blood in the external meatus and were diagnosed with urethral injury. The patients were taken to emergency surgery. Tunica defects varied between 1 and 2 cm. Incomplete urethral injuries were primarily repaired around 18 French Foley catheter. None of the patients reported penile deformity or painful erections. Their erection angles were found to be within the normal range. Conclusion Even though it is a relatively rare condition, penile fractures are so important that might cause serious complications when not treated surgically. A thorough anamnesis and physical examination suffice for diagnosis.

  18. Measurements of residual stress in fracture mechanics coupons

    Prime, Michael B [Los Alamos National Laboratory; Hill, Michael R [U.C. DAVIS; Nav Dalen, John E [HILL ENGINEERING


    This paper describes measurements of residual stress in coupons used for fracture mechanics testing. The primary objective of the measurements is to quantify the distribution of residual stress acting to open (and/or close) the crack across the crack plane. The slitting method and the contour method are two destructive residual stress measurement methods particularly capable of addressing that objective, and these were applied to measure residual stress in a set of identically prepared compact tension (C(T)) coupons. Comparison of the results of the two measurement methods provides some useful observations. Results from fracture mechanics tests of residual stress bearing coupons and fracture analysis, based on linear superposition of applied and residual stresses, show consistent behavior of coupons having various levels of residual stress.

  19. Effect of ground stress on hydraulic fracturing of methane well

    DU Chun-zhi; MAO Xian-biao; MIAO Xie-xing; WANG Peng


    Most of the coal reservoirs in China are of low-permeability, so hydraulic fracturing is widely used to improve the permeability in the extraction of gas by ground drilling. The ground stress around the well was analyzed by using theory of elasticity. The pressure when the well fractured is formulated and the effect of ground stress on pressure is discussed. The effect of ground-stress-differences on hydraulic fracturing was analyzed by using the numerical software RFPA2D-Flow in reference to the tectonic stress in Jincheng coal area. The results show that: 1) the position where initial fracture appears is random and fracture branches emerge when the fractures expand if ground stresses in any two directions within a horizontal plane are equal; 2) otherwise, the fractures expand in general along the direction of maximum ground stress and the critical pressure decreases with increasing ground-stress-differences and 3) the preferred well-disposition pattern is diamond shaped. The preferred well spacing is 250 m×300 m. This study can provide a reference for the design of wells.

  20. Transverse Stress Fracture of the Proximal Patella

    Atsumi, Satoru; Arai, Yuji; Kato, Ko; Nishimura, Akinobu; Nakazora, Shigeto; Nakagawa, Shuji; Ikoma, Kazuya; Fujiwara, Hiroyoshi; Sudo, Akihiro; Kubo, Toshikazu


    Abstract Among stress fractures associated with sports activities, patellar stress fracture is rare. Regarding patella stress fractures, so far only distal transverse or lateral longitudinal fractures have been reported, but there are no reports of transverse fractures occurring in the proximal patella. We describe an extremely rare case of transverse stress fracture of proximal patella in a 9-year-old athlete. A 9-year old boy, who participated in sports (sprints and Kendo) presented with left knee pain without any external injury. In plain radiographs, a fracture line was observed in the proximal 1/3 of the left patella, and a patella stress fracture was diagnosed. For treatment, because 7 months of conservative therapy showed no improvement, internal fixation was carried out using Acutrak screws, and bone union was thus achieved. Three months after the operation, he was able to return to his previous level of athletic sports activity. Regarding the mechanism of onset, it is believed that the causes are longitudinal traction force and patellofemoral contact pressure. On the other hand, the contact region of the patella with the femur changes with the flexion angle of the knee. In the current case, the fracture occurred at a site where the patella was in contact with the femur at a flexion angle of >90°, so it is believed that it occurred as a clinical condition from being subjected to repeated longitudinal traction force and patellofemoral contact pressure at a flexion angle of >90°, during the sports activities of sprints and Kendo. The nonunion of the transverse stress fracture of his proximal patella was successfully treated with internal fixation using Acutrak screws. PMID:26871789

  1. Genetic predisposition for femoral neck stress fractures in military conscripts

    Barral Sandra; Sahi Timo; Ruohola Juha-Petri; Solovieva Svetlana; Pihlajamäki Harri; Hartikka Heini; Korvala Johanna; Ott Jürg; Ala-Kokko Leena; Männikkö Minna


    Abstract Background Stress fractures are a significant problem among athletes and soldiers and may result in devastating complications or even permanent handicap. Genetic factors may increase the risk, but no major susceptibility genes have been identified. The purpose of this study was to search for possible genetic factors predisposing military conscripts to femoral neck stress fractures. Results Eight genes involved in bone metabolism or pathology (COL1A1, COL1A2, OPG, ESR1, VDR, CTR, LRP5...

  2. Stress Fractures of the Foot and Ankle in Athletes

    Mayer, Stephanie W.; Joyner, Patrick W.; Almekinders, Louis C.; Parekh, Selene G.


    Context: Stress fractures of the foot and ankle are a common problem encountered by athletes of all levels and ages. These injuries can be difficult to diagnose and may be initially evaluated by all levels of medical personnel. Clinical suspicion should be raised with certain history and physical examination findings. Evidence Acquisition: Scientific and review articles were searched through PubMed (1930-2012) with search terms including stress fractures and 1 of the following: foot ankle, medial malleolus, lateral malleolus, calcaneus, talus, metatarsal, cuboid, cuneiform, sesamoid, or athlete. Study Design: Clinical review. Level of Evidence: Level 5. Results: Stress fractures of the foot and ankle can be divided into low and high risk based upon their propensity to heal without complication. A wide variety of nonoperative strategies are employed based on the duration of symptoms, type of fracture, and patient factors, such as activity type, desire to return to sport, and compliance. Operative management has proven superior in several high-risk types of stress fractures. Evidence on pharmacotherapy and physiologic therapy such as bone stimulators is evolving. Conclusion: A high index of suspicion for stress fractures is appropriate in many high-risk groups of athletes with lower extremity pain. Proper and timely work-up and treatment is successful in returning these athletes to sport in many cases. Low-risk stress fracture generally requires only activity modification while high-risk stress fracture necessitates more aggressive intervention. The specific treatment of these injuries varies with the location of the stress fracture and the goals of the patient. PMID:25364480

  3. Emergence of anomalous transport in stressed rough fractures

    Kang, Peter K.; Brown, Stephen; Juanes, Ruben


    We report the emergence of anomalous (non-Fickian) transport through a rough-walled fracture as a result of increasing normal stress on the fracture. We show that the origin of this anomalous transport behavior can be traced to the emergence of a heterogeneous flow field dominated by preferential channels and stagnation zones, as a result of the larger number of contacts in a highly stressed fracture. We show that the velocity distribution determines the late-time scaling of particle spreading, and velocity correlation determines the magnitude of spreading and the transition time from the initial ballistic regime to the asymptotic anomalous behavior. We also propose a spatial Markov model that reproduces the transport behavior at the scale of the entire fracture with only three physical parameters. Our results point to a heretofore unrecognized link between geomechanics and particle transport in fractured media.

  4. 3-D description of fracture surfaces and stress-sensitivity analysis for naturally fractured reservoirs

    Zhang, S.Q.; Jioa, D.; Meng, Y.F.; Fan, Y.


    Three kinds of reservoir cores (limestone, sandstone, and shale with natural fractures) were used to study the effect of morphology of fracture surfaces on stress sensitivity. The cores, obtained from the reservoirs with depths of 2170 to 2300 m, have fractures which are mated on a large scale, but unmated on a fine scale. A specially designed photoelectric scanner with a computer was used to describe the topography of the fracture surfaces. Then, theoretical analysis of the fracture closure was carried out based on the fracture topography generated. The scanning results show that the asperity has almost normal distributions for all three types of samples. For the tested samples, the fracture closure predicted by the elastic-contact theory is different from the laboratory measurements because plastic deformation of the aspirates plays an important role under the testing range of normal stresses. In this work, the traditionally used elastic-contact theory has been modified to better predict the stress sensitivity of reservoir fractures. Analysis shows that the standard deviation of the probability density function of asperity distribution has a great effect on the fracture closure rate.

  5. Numerical Investigation on Stress Shadowing in Fluid Injection-Induced Fracture Propagation in Naturally Fractured Geothermal Reservoirs

    Yoon, Jeoung Seok; Zimmermann, Günter; Zang, Arno


    In low permeability shale reservoirs, multi-stage hydraulic fracturing is largely used to increase the productivity by enlarging the stimulated rock volume. Hydraulic fracture created alters the stress field around it, and affects the subsequent fractures by the change of the stress field, in particular, mostly increased minimum principal stress at the area of subsequent fracturing. This is called stress shadow which accumulates as the fracturing stages advance from toe to heel. Hydraulic fractures generated in such altered stress field are shorter and compact with orientation deviating significantly from the far-field maximum horizontal stress orientation. This paper presents 2D discrete element-based numerical modeling of multi-stage hydraulic fracturing in a naturally fractured reservoir and investigates stress shadowing. The stress shadowing is tested with two different injection scenarios: constant and cyclic rate injections. The results show that cyclic injection tends to lower the effect of stress shadow as well as mitigates the magnitude of the induced seismicity. Another modeling case is presented to show how the stress shadow can be utilized to optimize a hydraulic fracture network in application to Groß Schönebeck geothermal reservoir, rather than being mitigated. The modeling demonstrated that the stress shadow is successfully utilized for optimizing the geothermal heat exchanger by altering the initial in situ stress field from highly anisotropic to less or even to isotropic.

  6. Genetic predisposition for femoral neck stress fractures in military conscripts

    Barral Sandra


    Full Text Available Abstract Background Stress fractures are a significant problem among athletes and soldiers and may result in devastating complications or even permanent handicap. Genetic factors may increase the risk, but no major susceptibility genes have been identified. The purpose of this study was to search for possible genetic factors predisposing military conscripts to femoral neck stress fractures. Results Eight genes involved in bone metabolism or pathology (COL1A1, COL1A2, OPG, ESR1, VDR, CTR, LRP5, IL-6 were examined in 72 military conscripts with a femoral neck stress fracture and 120 controls. The risk of femoral neck stress fracture was significantly higher in subjects with low weight and body mass index (BMI. An interaction between the CTR (rs1801197 minor allele C and the VDR C-A haplotype was observed, and subjects lacking the C allele in CTR and/or the C-A haplotype in VDR had a 3-fold higher risk of stress fracture than subjects carrying both (OR = 3.22, 95% CI 1.38-7.49, p = 0.007. In addition, the LRP5 haplotype A-G-G-C alone and in combination with the VDR haplotype C-A was associated with stress fractures through reduced body weight and BMI. Conclusions Our findings suggest that genetic factors play a role in the development of stress fractures in individuals subjected to heavy exercise and mechanical loading. The present results can be applied to the design of future studies that will further elucidate the genetics of stress fractures.

  7. Rare stress fracture: longitudinal fracture of the femur.

    Pérez González, M; Velázquez Fragua, P; López Miralles, E; Abad Moretón, M M


    42-year-old man with pain in the posterolateral region of the right knee that began while he was running. Initially, it was diagnosed by magnetic resonance (MR) as a possible aggressive process (osteosarcoma or Ewing's sarcoma) but with computed tomography it was noted a cortical hypodense linear longitudinal image with a continuous, homogeneous and solid periosteal reaction without clear soft tissue mass that in this patient suggest a longitudinal distal femoral fatigue stress fracture. This type of fracture at this location is very rare. Stress fractures are entities that can be confused with an agressive process. MR iscurrently the most sensitive and specific imaging method for its diagnosis. Copyright © 2017 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.


    Sanda Dubravcic-Simunjak


    Full Text Available Figure skating is a physically demanding sport that requires a unique combination of artistic ability, speed, agility, flexibility and power. During the last decades not only the competitive schedule has become tougher, but after introduction of the new judging system in 2003, also more emphasis is put on difficult technical elements, jumps, steps and spins (ISU Rules, 2006. More studies about possible increasing prevalence of stress fractures in figure skaters and contributing factors are lacking (Dubravcic-Simunjak et al., 2003; Moran, 2000; Pecina et al., 1990. Therefore the aim of this study was to obtain data about the current stress fracture cumulative risk among elite junior and senior figure skaters, as well as possible factors that may contribute to stress fracture incidence. An anonymous questionnaire, divided into 5 sections, inquired about the prevalence of stress fracture were mailed and distributed to all 62 International Skating Union (ISU members by the ISU headquarters in Lausanne, Switzerland. The guidelines of the Helsinki declaration 2004 were followed. From the 644 skaters who received the questionnaire, 412 completed ones were returned from 110 female juniors (78 single skaters, 12 pair skaters and 20 ice dancers and 135 female seniors (97 single skaters, 16 pair skaters and 22 ice dancers and from 79 male juniors (47 single skaters, 12 pair skaters and 20 ice dancers and 88 male seniors (50 single skaters, 16 pair skaters and 22 ice dancers, coming from different ISU members. The response rate was 62% in females and 67% in males. The median age for female skaters was 16 years and for males 18 years (range 12-25 years. All participants started to skate between 3 and 6 years of age and started to compete in national and international competitions when they were between 5 and 7 years old. At the time of this analysis, they had been skating between 9 and 20 years.In females 41 (16.7%, and in males 25 (13.8% figure skaters

  9. Experimental study on water seepage constitutive law of fracture in rock under 3D stress

    赵阳升; 杨栋; 郑少河; 胡耀青


    The test method and test result of water seepage constitutive law of fracture in rock under 3D stress are introduced. A permeability coefficient formula including the coefficient of fracture connection, normal stiffness, 3D stress, initial width of fracture and Poisson ratio is presented based on the analysis of the test theory and its result.

  10. Self-reported versus diagnosed stress fractures in norwegian female elite athletes.

    Oyen, Jannike; Torstveit, Monica Klungland; Sundgot-Borgen, Jorunn


    The aim of this study was to determine the prevalence of self- reported versus diagnosed stress fractures in female elite athletes and non-athletic controls. A random sample of Norwegian elite athletes from the national teams, aged 13-39 years (n = 186) and a random sample of non-athletic controls (n = 145) in the same age group participated in the study. The athletes represented a junior- or senior team, or a recruiting squad for one of these teams, in one of 46 different sports/events. A higher percentage of athletes self-reported stress fractures (14.0%) compared to those diagnosed with stress fractures (8.1%) (p stress fractures, but none of them were diagnosed with stress fractures. These results indicate that self-reporting of stress fractures has low validity. This finding has important implications for further research on stress fractures in athletes. Key pointsThis study is the first to compare self-reported and diagnosed stress fractures in the total population of elite athletes representing all kinds of sports.The results indicate that self-reporting of stress fractures has low validity in both athletes and non-athletic controls, and other measurement methods should be considered when evaluating possible stress fractures.Based on our results, stress fractures seem to be a sport-related injury.

  11. Transverse Stress Fracture of the Proximal Patella: A Case Report

    Atsumi, Satoru; Arai, Yuji; Kato, Ko; Nishimura, Akinobu; Nakazora, Shigeto; Nakagawa, Shuji; Ikoma, Kazuya; Fujiwara, Hiroyoshi; Sudo, Akihiro; Kubo, Toshikazu


    .... Regarding patella stress fractures, so far only distal transverse or lateral longitudinal fractures have been reported, but there are no reports of transverse fractures occurring in the proximal patella...

  12. Lumbar facet stress fracture in a ballet dancer.

    Fehlandt, A F; Micheli, L J


    A frequent cause of back pain in athletes and dancers is stress injury to the posterior vertebral elements. Stress fractures affect the pars interarticularis and, rarely, other vertebral regions. The authors present their experience with the diagnosis and treatment of a fourth lumbar inferior articular facet stress fracture in a ballerina in this brief report and discuss the literature concerning posterior element stress fractures.

  13. Optimization of Multi-Cluster Fracturing Model under the Action of Induced Stress in Horizontal Wells

    Shanyong Liu


    Full Text Available Volume fracturing in shale gas forms complex fracture networks and increases stimulated reservoir volume through large-scale fracturing operation with plug-perforation technology. However, some perforation clusters are stimulated unevenly after fracturing. This study aims to solve this problem by analyzing the shortcomings of the conventional fracturing model and developing a coupled model based on the 2D fracture motion equation, energy conservation law, linear elastic mechanics, and stress superposition principle. First, a multi-fracture in-situ stress model was built by studying the induced stress produced by the fracture initiation to deduce the multi-fracture induced stress impact factor on the basis of the stress superposition principle. Then, the classical Perkins–Kern–Nordgren model was utilized with the crustal stress model. Finally, a precise fracturing design method was used to optimize perforation and fracturing parameters under the new model. Results demonstrate that the interference effect among fractures is the major factor causing the non-uniform propagation of each fracture. Compression on the main horizontal stress increases the net pressure. Therefore, both the degree of operation difficulty and the complexity of fracture geometry are improved. After applying the optimal design, the production is increased by 20%, and the cost is reduced by 15%.

  14. Stress generation and hierarchical fracturing in reactive systems

    Jamtveit, B.; Iyer, K.; Royne, A.; Malthe-Sorenssen, A.; Mathiesen, J.; Feder, J.


    Hierarchical fracture patterns are the result of a slowly driven fracturing process that successively divides the rocks into smaller domains. In quasi-2D systems, such fracture patterns are characterized by four sided domains, and T-junctions where new fractures stop at right angles to pre-existing fractures. We describe fracturing of mm to dm thick enstatite layers in a dunite matrix from the Leka ophiolite complex in Norway. The fracturing process is driven by expansion of the dunite matrix during serpentinization. The cumulative distributions of fracture lengths show a scaling behavior that lies between a log - normal and power law (fractal) distribution. This is consistent with a simple fragmentation model in which domains are divided according to a 'top hat' distribution of new fracture positions within unfractured domains. Reaction-assisted hierarchical fracturing is also likely to be responsible for other (3-D) structures commonly observed in serpentinized ultramafic rocks, including the mesh-textures observed in individual olivine grains, and the high abundance of rectangular domains at a wide range of scales. Spectacular examples of 3-D hierarchical fracture patterns also form during the weathering of basaltic intrusions (dolerites). Incipient chemical weathering of dolerites in the Karoo Basin in South Africa occurs around water- filled fractures, originally produced by thermal contraction or by externally imposed stresses. This chemical weathering causes local expansion of the rock matrix and generates elastic stresses. On a mm to cm scale, these stresses lead to mechanical layer-by-layer spalling, producing the characteristic spheroidal weathering patterns. However, our field observations and computer simulations demonstrate that in confined environments, the spalling process alone is unable to relieve the elastic stresses. In such cases, chemical weathering drives a much larger scale hierarchical fracturing process in which fresh dolerite undergoes a

  15. Stress Fracture of the Proximal Fibula in Military Recruits

    Hong, Seoung Hwan; Chu, In Tak


    Background We wanted to report on stress fracture of the proximal fibula and to suggest the pathomechanism of this fracture. Methods Between April 2004 through April 2005, the military recruits who complained of leg pain during the 6 weeks basic training in the Republic of Korea Marine Corps education and training group were evaluated according to their clinical manifestations and plain radiographs. Results Twelve recruits of 635 recruits who complained leg pain were diagnosed as having fibul...

  16. Acetabular stress fractures in military endurance athletes and recruits: incidence and MRI and scintigraphic findings

    Williams, T.R. [Portsmouth Naval Medical Center, Radiology Department, Charette Health Care Center, Portsmouth, VA (United States); Puckett, M.L.; Shin, A.Y.; Gorman, J.D. [Naval Medical Center San Diego, Radiology Department, San Diego, CA (United States); Denison, G. [US Naval Hospital Guam (United States)


    Objective: To evaluate the incidence and the MRI and scintigraphic appearance of acetabular stress (fatigue) fractures in military endurance athletes and recruits. Design and patients: One hundred and seventy-eight active duty military endurance trainees with a history of activity-related hip pain were evaluated by both MRI and bone scan over a 2-year period. Patients in the study ranged in age from 17 to 45 years. They had hip pain related to activity and had plain radiographs of the hip and pelvis that were interpreted as normal or equivocal. The study was originally designed to evaluate the MRI and scintigraphic appearance of femoral neck stress fractures. Patients had scintigraphy and a limited MRI examination (coronal imaging only) within 48 h of the bone scan. Twelve patients demonstrated imaging findings compatible with acetabular stress fractures. Results: Stress fractures are common in endurance athletes and in military populations; however, stress fracture of the acetabulum is uncommon. Twelve of 178 patients (6.7%) in our study had imaging findings consistent with acetabular stress fractures. Two patterns were identified. Seven of the 12 (58%) patients had acetabular roof stress fractures. In this group, two cases of bilateral acetabular roof stress fractures were identified, one with a synchronous tensile sided femoral neck stress fracture. The remaining five of 12 (42%) patients had anterior column stress fractures, rarely occurring in isolation, and almost always occurring with inferior pubic ramus stress fracture (4 of 5, or 80%). One case of bilateral anterior column stress fractures was identified without additional sites of injury. Conclusions: Stress fractures are commonplace in military populations, especially endurance trainees. Acetabular stress fractures are rare and therefore unrecognized, but do occur and may be a cause for activity-related hip pain in a small percentage of military endurance athletes and recruits. (orig.)

  17. [Stress fractures of the distal fibula in an osteoporotic woman].

    Schwartz, Frederik; Heerfordt, Ida Marie


    We report a case of an 81-year-old osteoporotic woman, who suffered stress fractures of the distal fibula on both sides within a two-year period. The risk factors for stress fractures are reviewed and the importance of a high index of suspicion for stress fractures is emphasized. When a stress fracture is suspected it should lead to plain radiography and treatment with protected weight-bearing with crutches or a brace.

  18. Analysis of fracture patterns and local stress field variations in fractured reservoirs

    Deckert, Hagen; Drews, Michael; Fremgen, Dominik; Wellmann, J. Florian


    A meaningful qualitative evaluation of permeabilities in fractured reservoirs in geothermal or hydrocarbon industry requires the spatial description of the existing discontinuity pattern within the area of interest and an analysis how these fractures might behave under given stress fields. This combined information can then be used for better estimating preferred fluid pathway directions within the reservoir, which is of particular interest for defining potential drilling sites. A description of the spatial fracture pattern mainly includes the orientation of rock discontinuities, spacing relationships between single fractures and their lateral extent. We have examined and quantified fracture patterns in several outcrops of granite at the Costa Brava, Spain, and in the Black Forest, Germany, for describing reservoir characteristics. For our analysis of fracture patterns we have used photogrammetric methods to create high-resolution georeferenced digital 3D images of outcrop walls. The advantage of this approach, compared to conventional methods for fracture analysis, is that it provides a better 3D description of the fracture geometry as the entity of position, extent and orientation of single fractures with respect to their surrounding neighbors is conserved. Hence for instance, the method allows generating fracture density maps, which can be used for a better description of the spatial distribution of discontinuities in a given outcrop. Using photogrammetric techniques also has the advantage to acquire very large data sets providing statistically sound results. To assess whether the recorded discontinuities might act as fluid pathways information on the stress field is needed. A 3D model of the regional tectonic structure was created and the geometry of the faults was put into a mechanical 3D Boundary Element (BE) Model. The model takes into account the elastic material properties of the geological units and the orientation of single fault segments. The

  19. Effect of electric field, stress and environment on delayed fracture of a PZT-5 ferroelectric ceramic

    WANG; Yi; SU; Yanjing; CHU; Wuyang; QIAO; Lijie


    The combined effect of electric and mechanical loading on fracture of a PZT-5 ferroelectric ceramic in silicone oil has been investigated using a single edge notched specimen. The results show that the fracture toughness and the threshold stress intensity factor of delayed fracture in silicone oil, i.e. stress corrosion cracking, decrease linearly with the increasing applied electric field, either positive or negative. For the PZT-5 ferroelectric ceramics, delayed fracture in silicone oil under sustained positive or negative field can occur, and the threshold field for delayed fracture under sustained positive or negative field decreases linearly with applied stress intensity factor. The combined effect of electric and mechanical loading on delayed fracture in silicone oil includes fieldenhancing delayed fracture under sustained load and stress-enhancing delayed fracture in silicone oil under sustained field.

  20. Seepage properties of a single rock fracture subjected to triaxial stresses


    Coupled properties of seepage and stress fields of rock fractures greatly influence the safety of geotechnical engineering work.Based on the closing defomation principle of a single rock fracture,equations describing relationships of aperture and triaxial stresses are developed,and coupled models of seepage and triaxial stresses are proposed.Seepage tests are conducted under triaxial stress conditions by adopting hard granite specimens with an artificial fracture.The results show that the normal stress,lateral stress and seepage pressure significantly affect the flow behavior of rock fractures,and that hydraulic conductivity decreases with increasing normal.stress,but increases with rising lateral stress or seepage pressure.In addition,an exponential function provides a good representation of the seepage characteristics of a single rock fracture subjected to triaxial stresses.

  1. MRI examination of stress fractures. Kernspintomographische Untersuchungen von Stressfrakturen

    Yousry, T.; Fink, U.; Breitner, S.; Stelzer, A.; Tiling, R.; Staebler, A. (Klinikum Grosshadern, Muenchen (Germany, F.R.). Radiologische Klinik und Poliklinik)


    Stress fractures can represent a diagnostic problem especially in their differentiation from bone tumours. 6 patients with 7 lesions were examined. MRI visualised the stress fractures and established the diagnosis of stress fracture vs. tumour in 6 cases. In the seventh, biopsy having been performed, a tumour was ruled out. MRI is more sensitive than radiography in the detection of stress fractures, showing the characteristic changes earlier. MRI, being a very sensitive method in the diagnosis of stress fractures and a reliable one in their differentiation from bone tumours, can be applied in cases of unusual clinical course and difficult radiological diagnosis prior to biopsy. (orig.).

  2. Dietary intake and stress fractures among elite male combat recruits

    Moran Daniel S


    Full Text Available Abstract Background Appropriate and sufficient dietary intake is one of the main requirements for maintaining fitness and health. Inadequate energy intake may have a negative impact on physical performance which may result in injuries among physically active populations. The purpose of this research was to evaluate a possible relationship between dietary intake and stress fracture occurrence among combat recruits during basic training (BT. Methods Data was collected from 74 combat recruits (18.2 ± 0.6 yrs in the Israeli Defense Forces. Data analyses included changes in anthropometric measures, dietary intake, blood iron and calcium levels. Measurements were taken on entry to 4-month BT and at the end of BT. The occurrence of stress reaction injury was followed prospectively during the entire 6-month training period. Results Twelve recruits were diagnosed with stress fracture in the tibia or femur (SF group. Sixty two recruits completed BT without stress fractures (NSF. Calcium and vitamin D intakes reported on induction day were lower in the SF group compared to the NSF group-38.9% for calcium (589 ± 92 and 964 ± 373 mg·d-1, respectively, p -1, respectively, p Conclusions The development of stress fractures in young recruits during combat BT was associated with dietary deficiency before induction and during BT of mainly vitamin D and calcium. For the purpose of intervention, the fact that the main deficiency is before induction will need special consideration.

  3. [Stress fracture after changing to barefoot running].

    Christensen, Mikkel


    Barefoot running is increasing in popularity but little is known about the implications in respect to injuries. It has been proposed that barefoot running is associated with a decrease in running injuries as it represents a more natural way of running. A 50-year-old runner with a weekly running distance of 50 km presented suffering from a stress fracture of the second metatarsal after six weeks of intensive barefoot running.

  4. Role of MRI in hip fractures, including stress fractures, occult fractures, avulsion fractures

    Nachtrab, O. [Department of Radiology, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Gobowen, Oswestry Shropshire SY10 7AG (United Kingdom); Cassar-Pullicino, V.N., E-mail: [Department of Radiology, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Gobowen, Oswestry Shropshire SY10 7AG (United Kingdom); Lalam, R.; Tins, B.; Tyrrell, P.N.M.; Singh, J. [Department of Radiology, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Gobowen, Oswestry Shropshire SY10 7AG (United Kingdom)


    MR imaging plays a vital role in the diagnosis and management of hip fractures in all age groups, in a large spectrum of patient groups spanning the elderly and sporting population. It allows a confident exclusion of fracture, differentiation of bony from soft tissue injury and an early confident detection of fractures. There is a spectrum of MR findings which in part is dictated by the type and cause of the fracture which the radiologist needs to be familiar with. Judicious but prompt utilisation of MR in patients with suspected hip fractures has a positive therapeutic impact with healthcare cost benefits as well as social care benefits.

  5. Atypical stress-avulsion fracture of the Lisfranc joint complex.

    O'Neill, Barry J


    Antiphospholipid syndrome and systemic erythematosus have been associated with metatarsal stress fractures. Stress fractures of the Lisfranc joint complex are uncommon injuries but have been reported to occur most frequently in ballet dancers. We present a case of an avulsion fracture of the Lisfranc joint complex that occurred spontaneously. We have reviewed the association between systemic conditions and metatarsal fractures and proposed a series of hypothetical pathological events that may have contributed to this unusual injury.

  6. A Fracture Probability Competition Mechanism of Stress Corrosion Cracking

    Yanliang HUANG


    The stress corrosion cracking (SCC) of austenitic stainless steel was studied via polarization,slow strain rate and scanning electron microscope (SEM) techniques. Many SCC mechanisms have been proposed in which hydrogen embrittlement and passive film rupture-repassivation theories are generally accepted, but they can hardly explain the SCC mechanism of austenitic stainless steel in acidic chloride solution adequately, because the steel is in active dissolution state and cathodic polarization can prevent it from occurring. Our experiment shows that the anodic current increases the creep rate and decreases the plastic strength of the material on single smooth specimen as well as at the SCC crack tip. The fractured surface was characterized as brittle cleavage, while the surface crack of smooth specimen was almost vertical to the tensile strength, which can confirm that the cracks were caused by tensile stresses. A fracture probability competition mechanism of SCC was proposed on the basis of the experimental results combined with the viewpoint of ductile-brittle fracture competition. When the anodic dissolution current is increased to a certain degree, the probability of fracture by tensile stress will exceed that by shear stress, and the brittle fracture will occur. The proposed SCC mechanism can not only explain the propagation of SCC cracks but can explain the crack initiation as well. The strain on the surface distributes unevenly when a smooth specimen is deformed, so does the anodic current distribution. The crack will initiate at a point where the anodic current density is large enough to cause the material at a specific point to fracture in brittle manner.

  7. Spinal fractures resulting from traumatic injuries

    Heidari Pedram; Zarei Mohammad Reza; Rasouli Mohammad Reza; Alexander R Vaccaro; Rahimi-Movaghar Vafa


    Objective:To illustrate mechanisms of spine fractures and the pattern of spinal injuries characterized by the major mechanisms in urban population of Iran.Methods:Data regarding spinal injuries including demographics,mechanism and level of spinal injury,abbreviated injury score,associated injuries and final fate of the patients were extracted from the Iranian national trauma registry database from 1999 to 2004.Results:A total of 619 patients with traumatic spine fractures were identified,of whom 68.5% were males.The peak frequency of these injuries occurred in the 21-40 year age-group.Accidental falls and road traffic crashes(RTCs)were the most common mechanisms of spinal fractures(47.2% and 44.1%,respectively).RTCs tended to occur in younger patients compared with accidental falls.The most common spinal region for spinal fracture was the lumbar spine(53.63%).Cervical spine fractures were significantly more common in RTCs,while lumbar spine fractures were more common in accidental falls(P<0.001).A total of 171(27.6%)patients had associated non-spinal injuries,of whom 127 had associated extremity injuries,and 55 had head injuries.Thirty-six(5.6%)patients had spinal cord injury(SCI).The injury severity score of the RTC group was significantly higher than that of accidental falls(P=0.002).Fifteen(4%)patients died of traumatic injuries.The rate of death was significantly higher in RTCs compared with accidental falls(5.1% vs 2.1%,P=0.039).Conclusions:The patterns of spinal fractures are similar to those reported from developed countries.RTCs tend to affect the younger age population and are associated with a higher degree of associated injuries and mortality than accidental falls.Therefore preventive strategies should be based on reduction of the number and severity of RTCs.

  8. Application of the results of pipe stress analyses into fracture mechanics defect analyses for welds of nuclear piping components; Uebernahme der Ergebnisse von Rohrsystemanalysen (Spannungsanalysen) fuer bruchmechanische Fehlerbewertungen fuer Schweissnaehte an Rohrleitungsbauteilen in kerntechnischen Anlagen

    Dittmar, S.; Neubrech, G.E.; Wernicke, R. [TUeV Nord SysTec GmbH und Co.KG (Germany); Rieck, D. [IGN Ingenieurgesellschaft Nord mbH und Co.KG (Germany)


    For the fracture mechanical assessment of postulated or detected crack-like defects in welds of piping systems it is necessary to know the stresses in the un-cracked component normal to the crack plane. Results of piping stress analyses may be used if these are evaluated for the locations of the welds in the piping system. Using stress enhancing factors (stress indices, stress factors) the needed stress components are calculated from the component specific sectional loads (forces and moments). For this procedure the tabulated stress enhancing factors, given in the standards (ASME Code, German KTA regulations) for determination and limitation of the effective stresses, are not always and immediately adequate for the calculation of the stress component normal to the crack plane. The contribution shows fundamental possibilities and validity limits for adoption of the results of piping system analyses for the fracture mechanical evaluation of axial and circumferential defects in welded joints, with special emphasis on typical piping system components (straight pipe, elbow, pipe fitting, T-joint). The lecture is supposed to contribute to the standardization of a code compliant and task-related use of the piping system analysis results for fracture mechanical failure assessment. [German] Fuer die bruchmechanische Bewertung von postulierten oder bei der wiederkehrenden zerstoerungsfreien Pruefung detektierten rissartigen Fehlern in Schweissnaehten von Rohrsystemen werden die Spannungen in der ungerissenen Bauteilwand senkrecht zur Rissebene benoetigt. Hierfuer koennen die Ergebnisse von Rohrsystemanalysen (Spannungsanalysen) genutzt werden, wenn sie fuer die Orte der Schweissnaehte im Rohrsystem ausgewertet werden. Mit Hilfe von Spannungserhoehungsfaktoren (Spannungsindizes, Spannungsbeiwerten) werden aus den komponentenweise berechneten Schnittlasten (Kraefte und Momente) die benoetigten Spannungskomponenten berechnet. Dabei sind jedoch die in den Regelwerken (ASME

  9. Composite fracture using the normal stress ratio theory

    Beuth, J. L., Jr.; Gurdal, Z.; Herakovich, C. T.


    Experiments were performed on center-notched specimens of unidirectional AS4/3501-6 graphite-epoxy subjected to varied far-field loading conditions. Specimens tested include on-axis and off-axis tensile coupons and Iosipescu shear specimens, allowing the study of normal, shear, and combined far-field loading conditions. From the tests, the direction of initial crack extension and the far-field stresses at crack initiation and fracture are obtained. The normal stress ratio theory is subsequently applied within a macroscopic-level homogeneous anisotropic stress solution to predict the direction of crack extension, critical stresses, and other crack growth behavior for the experiments. Comparison between experimental results and theoretical predictions indicates that application of the normal stress ratio theory within a macroscopic-level stress analysis has significant potential as an approach to modeling composite crack growth.

  10. Results of surgically treated talar fractures

    Ali Yeganeh; Atefe Alaee; Bahram Boddouhi; Ali Behkam-Rad; Gholamreza Shahoseini


    Objective:Talar fractures present a great challenge to surgeons due to poor treatment outcome and high incidence of sequelae.The purpose of this study was to report the surgical treatment outcome of displaced talar fractures treated by internal fixation.Methods:Atotal of 30 patients with a mean age of 38 years presenting with talar body or neck fractures were studied retrospectively to assess postoperative outcome based on American Orthopaedic Foot & Ankle Society AnkleHindfoot scale.Results:Postoperatively,malunion was found in 18 cases,infection in 5 cases and avascular necrosis in 12 cases.There were 12 cases with subtalar arthritis and 18 cases with both subtalar and malleolar arthritis.The average score of questionnaire was 64± 12.Functional score was 53± 15 and pain score was 65±13.Range of motion failure was detected as 15±4.Conclusion:Talar injuries can compromise motion of the foot and ankle and result in poor prognosis on longterm evaluation.Late complications subsequent to surgically treated talar body fractures are inevitable,and patients are supposed to be counseled about the adverse outcome.

  11. Modelling stress-dependent permeability in fractured rock including effects of propagating and bending fractures

    Latham, J.P.; Xiang, J.; Belayneh, M.; Nick, H.M.; Tsang, C.F.; Blunt, M.J.


    The influence of in-situ stresses on flow processes in fractured rock is investigated using a novel modelling approach. The combined finite-discrete element method (FEMDEM) is used to model the deformation of a fractured rock mass. The fracture wall displacements and aperture changes are modelled in

  12. Stress Related Fracturing in Dimension Stone Quarries

    Hamdi Deliormanli, Ahmet; Maerz, Norbert H.


    In Missouri, the horizontal stresses (pressures) in the near surface rock are uncommonly high. While the vertical stresses in rock are simply a function of the weight of the overlying rock, near surface stresses can be many times higher. The near surface horizontal stresses can be in excess of 5 times greater than the vertical stresses. In this research, Flatjack method was used to measure horizontal stress in Red Granite Quarry in Missouri. The flat jack method is an approved method of measuring ground stresses. A saw cut is used to “relax” the stress in the ground by allowing the rock to deform inwards the cut. A hydraulic flat jack is used to inflate the slot; to push the rock back to its stressed position, as measured by a strain gauge on either side of the slot. The pressure in the jack, when the rock is exactly back to its original position, is equal to the ground stress before the saw cut was made. According to the results, present production direction for each pit is not good because the maximum stress direction is perpendicular with production direction. This case causes unintentional breakage results in the loss rock. The results show that production direction should be changed.

  13. Stress Fracture and Nonunion of Coronoid Process in a Gymnast

    T. Hetling


    Full Text Available Background. Gymnasts have high mechanical loading forces of up to 14 times body weight. Overuse lesions are typical in wrists and stress fractures in the olecranon, while isolated fractures of the coronoid process are uncommon. We present a case of retraumatized nonunion stress fracture of the ulnar coronoid process. Case Description. A 19-year-old gymnast presented with elbow pain after training. Imaging confirmed an old fracture of the coronoid process. We describe a 6-month multiphase return to competition rehabilitation program, which allowed him to compete pain-freely. Literature Review. Acute and overuse injuries in gymnasts are known but no nonunion of the coronoid process has been described before. Only one case of stress fracture of coronoid process in a gymnast was reported. Purpose and Clinical Relevance. We could successfully and conservatively return to sport a reactivated nonunion of a stress fracture of the coronoid process.

  14. Stress fractures of forearm bones in military recruits of rifle drill training.

    Kuo, Chun-Lin; Pan, Ru-Yu; Wu, Jia-Lin; Huang, Wen-Sheng; Wang, Shyu-Jye


    Stress fractures rarely occur in the forearms. These injuries usually occur in healthy young patients, which are usually neglected by patients or physicians. Early diagnosis and treatment are important to avoid late complications of these fractures. The purpose of this study was to analyze a case series of military recruits who participated in rifle drill training and presented with forearm stress fractures at our institution. We evaluated 216 military recruits of rifle drill training. Twelve patients were diagnosed with forearm stress fractures by typical history, physical examination, laboratory studies, serial radiographs, and bone scan examinations. Eighteen fractures were found in 12 patients. On initial radiographs, 11 had periosteal reactions, 4 had callus formation with complete fracture lines, and 3 were normal. All 18 fractures had increase radioactivity in the involved middle (15 of 18) or distal (2 of 18) ulnae and one middle radius (1 of 18). Stress fractures of the forearms in military rifle drill training usually occur in middle ulnae. Fifty percent of them were bilateral fractures. A high index of suspicion is the key to diagnosis. Early diagnosis with conservative treatment can achieve satisfactory results and avoid late complications of stress fractures.


    Ran Yanovich


    Full Text Available To investigate the association of polymorphisms within candidate genes which we hypothesized may contribute to stress fracture predisposition, a case-control, cross- sectional study design was employed. Genotyping 268 Single Nucleotide Polymorphisms- SNPs within 17 genes in 385 Israeli young male and female recruits (182 with and 203 without stress fractures. Twenty-five polymorphisms within 9 genes (NR3C1, ANKH, VDR, ROR2, CALCR, IL6, COL1A2, CBG, and LRP4 showed statistically significant differences (p < 0.05 in the distribution between stress fracture cases and non stress fracture controls. Seventeen genetic variants were associated with an increased stress fracture risk, and eight variants with a decreased stress fracture risk. None of the SNP associations remained significant after correcting for multiple comparisons (false discovery rate- FDR. Our findings suggest that genes may be involved in stress fracture pathogenesis. Specifically, the CALCR and the VDR genes are intriguing candidates. The putative involvement of these genes in stress fracture predisposition requires analysis of more cases and controls and sequencing the relevant genomic regions, in order to define the specific gene mutations

  16. Oncogenic osteomalacia presenting as bilateral stress fractures of the tibia

    Ohashi, Kenjirou; Ohnishi, Takeshi; Ishikawa, Tohru [Department of Radiology, St. Marianna University Hospital, Kanagawa (Japan); Tani, Haruo [Department of Internal Medicine III, St. Marianna University Hospital, Kawasaki City, Kanagawa (Japan); Uesugi, Keisuke [Department of Otolaryngology, St. Marianna University Hospital, Kawasaki City, Kanagawa (Japan); Takagi, Masayuki [Department of Pathology, St. Marianna University Hospital, Kawasaki City, Kanagawa (Japan)


    We report on a patient with bilateral stress fractures of the tibia who subsequently showed classic biochemical features of oncogenic osteomalacia. Conventional radiographs were normal. MR imaging revealed symmetric, bilateral, band-like low-signal lesions perpendicular to the medial cortex of the tibiae and corresponding to the only lesions subsequently seen on the bone scan. A maxillary sinus lesion was subsequently detected and surgically removed resulting in prompt alleviation of symptoms and normalization of hypophosphatemia and low 1,25-(OH){sub 2} vitamin D{sub 3}. The lesion was pathologically diagnosed as a hemangiopericytoma-like tumor. Patients with oncogenic osteomalacia may present with stress fractures limited to the tibia, as seen in athletes. The clue to the real diagnosis lies in paying close attention to the serum phosphate levels, especially in patients suffering generalized symptoms of weakness and not given to unusual physical activity. (orig.) With 4 figs., 6 refs.

  17. Postpartum Sacral Stress Fracture: An Atypical Case Report

    Andrea Speziali


    Full Text Available Sacral stress fractures are common in elderly people. However, sacral stress fracture should be always screened in the differential diagnoses of low back pain during the postpartum period. We present a case of sacral fracture in a thirty-six-year-old woman with low back pain and severe right buttock pain two days after cesarean section delivery of a 3.9 Kg baby. The diagnosis was confirmed by MRI and CT scan, while X-ray was unable to detect the fracture. Contribution of mechanical factors during the cesarean section is not a reasonable cause of sacral fracture. Pregnancy and lactation could be risk factors for sacral stress fracture even in atraumatic delivery such as cesarean section. Our patient had no risk factors for osteoporosis except for pregnancy and lactation. Transient or focal osteoporosis is challenging to assess and it cannot be ruled out even if serum test and mineral density are within the normal range.

  18. Stress fracture in the world class athlete: a case study.

    Jensen, J E


    Stress fracture presents a difficult problem in the high performance, world-class athlete. Competitive demands provide little tolerance for, or agreement with, prolonged periods of rest which are the first line of conservative treatment methods. The use of a specifically programmed, pulsed, low-intensity ultrasound device to shorten the time of healing was investigated in a well-known gymnast with an Olympic deadline. Prior animal, in vitro, and clinical studies had established the safety and effectiveness of this device in fractures. The location of the stress injury was in the mid-tibia which is considered to present the greatest challenge to an early healing result. The low-intensity ultrasound device was prescribed for daily use at home. At 3 wk after the start of low-intensity ultrasound, the stress fracture responded well and the patient was allowed use of tumble track, trampoline, and to do some weight-bearing activities, such as jumping in the pool and loading-type activities. At 4.5 wk, the patient progressed to full workout activities and participated in a trial meet for the Olympics. At 6 wk, the patient's participation in the women's gymnastic team event was a factor in the United States receiving a gold medal.

  19. The impact of in-situ stress and outcrop-based fracture geometry on hydraulic aperture and upscaled permeability in fractured reservoirs

    Bisdom, Kevin; Bertotti, Giovanni; Nick, Hamidreza M.


    Aperture has a controlling impact on porosity and permeability and is a source of uncertainty in modeling of naturally fractured reservoirs. This uncertainty results from difficulties in accurately quantifying aperture in the subsurface and from a limited fundamental understanding of the mechanical and diagenetic processes that control aperture. In the absence of cement bridges and high pore pressure, fractures in the subsurface are generally considered to be closed. However, experimental work, outcrop analyses and subsurface data show that some fractures remain open, and that aperture varies even along a single fracture. However, most fracture flow models consider constant apertures for fractures. We create a stress-dependent heterogeneous aperture by combining Finite Element modeling of discrete fracture networks with an empirical aperture model. Using a modeling approach that considers fractures explicitly, we quantify equivalent permeability, i.e. combined matrix and stress-dependent fracture flow. Fracture networks extracted from a large outcropping pavement form the basis of these models. The results show that the angle between fracture strike and σ1 has a controlling impact on aperture and permeability, where hydraulic opening is maximum for an angle of 15°. At this angle, the fracture experiences a minor amount of shear displacement that allows the fracture to remain open even when fluid pressure is lower than the local normal stress. Averaging the heterogeneous aperture to scale up permeability probably results in an underestimation of flow, indicating the need to incorporate full aperture distributions rather than simplified aperture models in reservoir-scale flow models.

  20. Non-linear hydrotectonic phenomena: Part I - fluid flow in open fractures under dynamical stress loading

    Archambeau, C.B. [Univ. of Colorado, Boulder, CO (United States)


    A fractured solid under stress loading (or unloading) can be viewed as behaving macroscopically as a medium with internal, hidden, degrees of freedom, wherein changes in fracture geometry (i.e. opening, closing and extension) and flow of fluid and gas within fractures will produce major changes in stresses and strains within the solid. Likewise, the flow process within fractures will be strongly coupled to deformation within the solid through boundary conditions on the fracture surfaces. The effects in the solid can, in part, be phenomenologically represented as inelastic or plastic processes in the macroscopic view. However, there are clearly phenomena associated with fracture growth and open fracture fluid flows that produce effects that can not be described using ordinary inelastic phenomenology. This is evident from the fact that a variety of energy release phenomena can occur, including seismic emissions of previously stored strain energy due to fracture growth, release of disolved gas from fluids in the fractures resulting in enhanced buoyancy and subsequent energetic flows of gas and fluids through the fracture system which can produce raid extension of old fractures and the creation of new ones. Additionally, the flows will be modulated by the opening and closing of fractures due to deformation in the solid, so that the flow process is strongly coupled to dynamical processes in the surrounding solid matrix, some of which are induced by the flow itself.

  1. Unstable Jefferson fractures: Results of transoral osteosynthesis

    Yong Hu


    Full Text Available Background: Majority of C 1 fractures can be effectively treated conservatively by immobilization or traction unless there is an injury to the transverse ligament. Conservative treatment usually involves a long period of immobilization in a halo-vest. Surgical intervention generally involves fusion, eliminating the motion of the upper cervical spine. We describe the treatment of unstable Jefferson fractures designed to avoid these problems of both conservative and invasive methods. Materials and Methods: A retrospective review of 12 patients with unstable Jefferson fractures treated with transoral osteosynthesis of C 1 between July 2008 and December 2011 was performed. A steel plate and C 1 lateral mass screw fixation were used to repair the unstable Jefferson fractures. Our study group included eight males and four females with an average age of 33 years (range 23-62 years. Results: Patients were followed up for an average of 16 months after surgery. Range of motion of the cervical spine was by and large physiologic: Average flexion 35° (range 28-40°, average extension 42° (range 30-48°. Lateral bending to the right and left averaged 30° and 28° respectively (range 12-36° and 14-32° respectively. The average postoperative rotation of the atlantoaxial joint, evaluated by functional computed tomography scan was 60° (range 35-72°. Total average lateral displacement of the lateral masses was 7.0 mm before surgery (range 5-12 mm, which improved to 3.5 mm after surgery (range 1-6.5 mm. The total average difference of the atlanto-dens interval in flexion and extension after surgery was 1.0 mm (range 1-3 mm. Conclusions: Transoral osteosynthesis of the anterior ring using C 1 lateral mass screws is a viable option for treating unstable Jefferson fractures, which allows maintenance of rotation at the C 1-C 2 joint and restoration of congruency of the atlanto-occipital and atlantoaxial joints.

  2. Stress fracture of the distal fibula in flatfoot patients: case report

    Cheng, Yu; Yang, HuiLin; Ni, Li; Song, Dawei; Zhang, Hongtao


    The increase in proportional loading of the fibula with progression of hindfoot deformity would lead to high fibular loads during rapid walking, resulting in insufficiency fractures. We report an unusual mechanism of such fracture in a textile worker resulting from valgus alignment from a stage III flatfoot deformity. The stress fracture was missed initially and only confirmed by CT examination. The patient responded well to nonoperative treatment and had an excellent recovery with no residua...

  3. Navicular Stress Fracture Outcomes in Athletes: Analysis of 62 Injuries.

    Saxena, Amol; Behan, Shontal A; Valerio, Dallas L; Frosch, Dominick L

    The optimal treatment modalities for navicular stress fractures in athletes is currently unknown for this season-ending injury. The present study evaluated factors that might be significant and affect healing outcomes, specifically focusing on the return to activity (RTA) time and a decreased desired activity (DDA) after treatment in athletes. Such considerations included previous navicular stress fractures, patient demographic data and type of sport, and initiation time of treatment. The data from 59 patients with 62 fractures were prospectively analyzed from May 2005 through July 2016. The results showed a significant correlation between a previous navicular stress fracture and decreased desired activity. The average duration of symptoms before receiving definitive treatment was 8.8 months. Computed tomography as the initial imaging modality correlated positively with a correct diagnosis (1.00). In contrast, magnetic resonance imaging, when used initially, was only 71% accurate. Runners constituted most of the cohort at 38 (61.3%). Ten other athletes were involved in jumping sports. Of the 62 injuries, 21 (33.9%) were in elite or professional athletes, all of whom were able to RTA, with 1 patient, a 38-year-old world record holding runner, having a DDA. Seven refractures (11.2%) occurred an average >5 years after the initial injury, predominantly in those aged <21 years, none with previous surgery. Eight patients (12.9%) developed postinjury arthrosis, including 1 with DDA. Patients who underwent open reduction and internal fixation had a RTA of 4.56 months compared with those who had undergone nonoperative treatment, who had an average RTA of 3.97 months. Seven patients (11.2%) underwent screw removal and required a longer RTA. Overall, of the 62 injuries, the patients with 57 of the injuries (91.9%) were able to RTA at their preinjury level. Copyright © 2017 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  4. Evaluation results of using sole Ilizarov fixator in Pilon fractures

    Ahmad Reza Mirbolook


    Conclusion: According to the results obtained and comparing them with the results of other treatments ,one can claim that this treating approach is better than the others for pilon fractures,particularly for type 3c pilon fractures.

  5. Analyses of thermal stress and fracture during cryopreservation of blood vessel

    华泽钊; 徐红艳; 周国燕; 刘锦纷; 黄惠民; 丁文祥


    The occurrence of fractures in the vessel wall has been a major problem for human blood vessel cryopreservation. The large volumetric expansion of water during crystallization produces great inner stresses. To solve these complicated heat transfer and thermal stress problems, a model and an analytic method are presented in this paper, with which transient temperature field, the transient stress field inside the blood vessels during freezing can be calculated and analyzed, and the probable cracks or fractures can be predicted. The analytic results of sheep thoracic artery are consistent with the experimental observations of fractures.

  6. Stress analysis of fracture of atherosclerotic plaques: crack propagation modeling.

    Rezvani-Sharif, Alireza; Tafazzoli-Shadpour, Mohammad; Kazemi-Saleh, Davood; Sotoudeh-Anvari, Maryam


    Traditionally, the degree of luminal obstruction has been used to assess the vulnerability of atherosclerotic plaques. However, recent studies have revealed that other factors such as plaque morphology, material properties of lesion components and blood pressure may contribute to the fracture of atherosclerotic plaques. The aim of this study was to investigate the mechanism of fracture of atherosclerotic plaques based on the mechanical stress distribution and fatigue analysis by means of numerical simulation. Realistic models of type V plaques were reconstructed based on histological images. Finite element method was used to determine mechanical stress distribution within the plaque. Assuming that crack propagation initiated at the sites of stress concentration, crack propagation due to pulsatile blood pressure was modeled. Results showed that crack propagation considerably changed the stress field within the plaque and in some cases led to initiation of secondary cracks. The lipid pool stiffness affected the location of crack formation and the rate and direction of crack propagation. Moreover, increasing the mean or pulse pressure decreased the number of cycles to rupture. It is suggested that crack propagation analysis can lead to a better recognition of factors involved in plaque rupture and more accurate determination of vulnerable plaques.

  7. Unusual exercise-related stress fractures. Two case reports

    Fink-Bennett, D.M.; Benson, M.T.


    We describe two unusual exercise-related stress fractures, one in the sacroiliac joint of a long distance runner, the other in the body of the scapulae of an above-knee amputee. Each were detected on a 2-hour delay bone scan. To our knowledge, neither have been described scintigraphically. The bilateral scapular fracture is an unreported entity, and the fractured SI joint is a very uncommon site for an overuse injury.

  8. Dynamic Response in Transient Stress-Field Behavior Induced by Hydraulic Fracturing

    Jenkins, Andrew

    magnitude. These types of shifts are of great concern because they can impact subsequent fracture development causing non-uniform fracture propagation and the potential overlapping of fracture paths as they extend from the wellbore at the point of injection. The dynamics of stress variation that occur with respect to hydraulic fracturing is a somewhat new area of study. In order to accomplish the goals of this thesis and continue future research in this area a new transient model has been developed in order to asses these dynamic systems and determine their influence on fracture behavior. This applies the use of a fully coupled finite element method in 2-D using linear elastic fracture mechanics which is then expanded using displacement discontinuity to a cohesive zone model in 3-D. A static boundary element model was also used to determine stress fields surrounding static, predetermined fracture geometries. These models have been verified against analytical solutions for simple cases and are now being applied to more detailed case studies and analysis. These models have been briefly discussed throughout this thesis in order to give insight on their current capabilities and application as well as their future potential within this area of research. The majority of this work introduces transient stress field prediction to cases of single and multiple hydraulic fractures. The static assessment of these stresses is determined for verification of results to those found in publication which leads into these transient stress field variations. A new method has been developed and applied to the stress state prediction for the first time in a transient fracture model which is partly based upon a critical distance theory. These dynamic interactions can provide useful insight to pertinent issues within the petroleum and natural gas industry such as those to hydraulic fracturing fluid loss and induced seismic events, as well as to applications of efficiency and optimization of the

  9. Transverse Stress Fracture of the Proximal Patella: A Case Report.

    Atsumi, Satoru; Arai, Yuji; Kato, Ko; Nishimura, Akinobu; Nakazora, Shigeto; Nakagawa, Shuji; Ikoma, Kazuya; Fujiwara, Hiroyoshi; Sudo, Akihiro; Kubo, Toshikazu


    Among stress fractures associated with sports activities, patellar stress fracture is rare. Regarding patella stress fractures, so far only distal transverse or lateral longitudinal fractures have been reported, but there are no reports of transverse fractures occurring in the proximal patella. We describe an extremely rare case of transverse stress fracture of proximal patella in a 9-year-old athlete.A 9-year old boy, who participated in sports (sprints and Kendo) presented with left knee pain without any external injury. In plain radiographs, a fracture line was observed in the proximal 1/3 of the left patella, and a patella stress fracture was diagnosed. For treatment, because 7 months of conservative therapy showed no improvement, internal fixation was carried out using Acutrak screws, and bone union was thus achieved. Three months after the operation, he was able to return to his previous level of athletic sports activity.Regarding the mechanism of onset, it is believed that the causes are longitudinal traction force and patellofemoral contact pressure. On the other hand, the contact region of the patella with the femur changes with the flexion angle of the knee. In the current case, the fracture occurred at a site where the patella was in contact with the femur at a flexion angle of >90°, so it is believed that it occurred as a clinical condition from being subjected to repeated longitudinal traction force and patellofemoral contact pressure at a flexion angle of >90°, during the sports activities of sprints and Kendo. The nonunion of the transverse stress fracture of his proximal patella was successfully treated with internal fixation using Acutrak screws.

  10. Longitudinal stress fracture of the femur: A rare presentation

    Bilreiro, Carlos; Bahia, Carla; Castro, Miguel Oliveira e


    We present the case of an 80 year old woman with hip pain, caused by a longitudinal femoral insufficiency stress fracture, depicted with radiographs, CT and MR. This type of fracture is very rare, with only a few cases reported. We conducted a literature review and compared the findings with the present case. PMID:27069976

  11. Medial supracondylar stress fracture in an adolescent pitcher

    Chang, Eric Y.; Chung, Christine B. [VA San Diego Healthcare System, San Diego, CA (United States); University of California, San Diego Medical Center, San Diego, CA (United States); Fronek, Jan [Scripps Healthcare, La Jolla, CA (United States)


    We report the occurrence of a medial supracondylar stress fracture in an adolescent pitcher. To our knowledge, this fracture has not been described in the literature, and awareness of this entity allows initiation of therapy and precludes further unnecessary work-up. The radiographic, computed tomography, and magnetic resonance imaging appearances are reviewed and the mechanism of injury is discussed. (orig.)

  12. Lower thoracic rib stress fractures in baseball pitchers.

    Gerrie, Brayden J; Harris, Joshua D; Lintner, David M; McCulloch, Patrick C


    Stress fractures of the first rib on the dominant throwing side are well-described in baseball pitchers; however, lower thoracic rib fractures are not commonly recognized. While common in other sports such as rowing, there is scant literature on these injuries in baseball. Intercostal muscle strains are commonly diagnosed in baseball pitchers and have a nearly identical presentation but also a highly variable healing time. The diagnosis of a rib stress fracture can predict a more protracted recovery. This case series presents two collegiate baseball pitchers on one team during the same season who were originally diagnosed with intercostal muscle strains, which following magnetic resonance imaging (MRI) were found to have actually sustained lower thoracic rib stress fractures. The first sustained a stress fracture of the posterior aspect of the right 8th rib on the dominant arm side, while the second presented with a left-sided 10th rib stress fracture on the nondominant arm side. In both cases, MRI was used to visualize the fractures as plain radiographs are insensitive and commonly negative early in patient presentation. Patients were treated with activity modification, and symptomatic management for 4-6 weeks with a graduated return to throwing and competition by 8-10 weeks. The repetitive high stresses incurred by pitching may cause either dominant or nondominant rib stress fractures and this should be included in the differential diagnosis of thoracic injuries in throwers. It is especially important that athletic trainers and team physicians consider this diagnosis, as rib fractures may have a protracted course and delayed return to play. Additionally, using the appropriate imaging techniques to establish an accurate diagnosis can help inform return-to-play decisions, which have important practical applications in baseball, such as roster management and eligibility.

  13. MR semiology of stress fractures; Semiologie IRM des fractures de fatigue

    Boyer, B.; Cordoliani, Y.S.; Naudinat, E.; Sylvestre, A.; Pharaboz, C. [Hopital des Armees Begin, 94 - Saint-Mande (France)


    Nuclear Magnetic Resonance imaging can contribute to stress fractures diagnosis when it makes obvious the fracture line which signal is variable in function of site lesion. The importance of inflammatory reactions must not call the diagnosis in question again. 5 figs., 8 refs.

  14. The effect of multiaxial stress state on creep behavior and fracture mechanism of P92 steel

    Chang, Yuan; Xu, Hong, E-mail:; Ni, Yongzhong; Lan, Xiang; Li, Hongyuan


    The creep experiments on plain and double U-typed notched specimens were conducted on P92 steel at 650 °C. The notch strengthening effect was found in the notched specimens. Fracture appearance observed by scanning electron microscopy revealed that dimpled fracture for relatively blunt notched specimen, and dimpled fracture doubled with intergranular brittle fracture for relatively sharp notched specimen, which meant that fracture mechanism of P92 steel altered due to the presence of the notch. Meanwhile, based on Norton–Bailey and Kachanov–Robotnov constitutive models, a modified model was proposed. Finite element simulations were carried out to investigate the effect of multiaxial stress state on the creep behavior, fracture mechanism and damage evolvement of P92 steel. The simulation results agreed well with the fracture behaviors observed experimentally.

  15. 99mTc-MDP bone scintigraphy in the diagnosis of stress fracture of the metatarsal bones mimicking oligoarthritis

    Jauković Ljiljana


    Full Text Available Background. Stress fractures are the injuries of soft tissues and bones caused by intensive and repeated stress on a bone. Repeated submaximal stress disturbs the balance between the processes of bone production and resorption that results in fracture. Case report. We presented a case of a patient with stress fracture of metatarsal bone. The patient was diagnosed and treated as having reactive oligoarthritis caused by Chlamydia trachomatis and administered antibiotics. Initial plain radiography was negative for bone fracture. Tc-99m bone scintigraphy suggested stress fracture of the second metatarsal. Plain radiography was became positive three weeks later, showing callus formation in the proximal part of the second metatarsal. Conclusion. Bone scintigraphy is a diagnostic test of choice in early diagnosis of stress fracture, and it is important to apply it timely in order to include the entire therapy and prevent complications, as well as to let a patient return to previous daily activites.

  16. Measurement of residual stresses using fracture mechanics weight functions

    Fan, Y. [Bettis Atomic Power Laboratory, West Mifflin, PA (United States)


    A residual stress measurement method has been developed to quantify through-the-thickness residual stresses. Accurate measurement of residual stresses is crucial for many engineering structures. Fabrication processes such as welding and machining generate residual stresses that are difficult to predict. Residual stresses affect the integrity of structures through promoting failures due to brittle fracture, fatigue, stress corrosion cracking, and wear. In this work, the weight function theory of fracture mechanics is used to measure residual stresses. The weight function theory is an important development in computational fracture mechanics. Stress intensity factors for arbitrary stress distribution on the crack faces can be accurately and efficiently computed for predicting crack growth. This paper demonstrates that the weight functions are equally useful in measuring residual stresses. In this method, an artificial crack is created by a thin cut in a structure containing residual stresses. The cut relieves the residual stresses normal to the crack-face and allows the relieved residual stresses to deform the structure. Strain gages placed adjacent to the cut measure the relieved strains corresponding to incrementally increasing depths of the cut. The weight functions of the cracked body relate the measured strains to the residual stresses normal to the cut within the structure. The procedure details, such as numerical integration of the singular functions in applying the weight function method, will be discussed. (author)

  17. Treatment results in isolated humerus majus fractures

    Hakan Serhat Yanık


    Full Text Available Introduction: The aim of this study is to evaluate the resultsof patients with the isolated greater tubercul fractures(GTF of humerus who conservatively or surgicallytreated.Materials and methods: 23 patients were admitted (11women, 12 men with GTF (54% dominant side of 24shoulder between 2008 and 2011. All of patient wereevaluated with MRI as preoperatively soft tissue injury.There was supraspinatus muscle tear together with GTFin 3 case and their shoulder were arthroscopically assistedrotator cuff repair. Osteosynthesis was performed in 3case with screw and fixation in 2 case with suture. GTF of16 shoulder were conservatively treated. Shoulder functionafter treatment were evaluated according to Constantscore (CS, Quick-DASH score (QDS and VAS score.Results: Three patients with screw fixation had CS 68,6points, QDS 12,8 points, VAS score 1,66. Two patientswith suture fixation had 67,5 CS points, 5,1 QDS pointsp,and 2 VAS score. Three patients with rotator cuff tear repairhad 82,6 CS points, 16,6 QDS points, and 2,33 VASscore. In patients with conservatively treated mean CSwas 63,9 points, QDS 26,1 points, VAS 2,96 points.Conclusions: In this study, conservative and surgicaltreatment results were satisfactory. In terms of pain theresults were excellent. In conclusion, GTFs are rare buttrouble-free with a good observation and sufficient rehabilitation.J Clin Exp Invest 2012; 3 (3: 378-382Key words: Humerus, fracture, greater, tubercul

  18. Bilateral First Rib Stress Fractures in a Basketball Player

    Abidin (Radyoloji Kilincer


    Full Text Available I read the article published by Aydogdu et al with a great interest. I congratulate them for this successfully written case report. Additionally, I want to focus an important point about the case they presented is that the diagnosis in that case is likely stress fracture. It is understood from the text and title that they avoided to make a diagnosis of stress fracture in the case, despite of history of lifting heavy weights for three days. And also I decided to mention through this article to an example of our case with bilateral first rib old fractures.

  19. A case report of missed femoral neck stress fracture

    Onibere Oruaro Adebayo


    Full Text Available Femoral neck stress fracture (FNSF is an uncommon but potentially serious orthopaedic problem. This is a case report on missed femoral neck stress fracture in a 62-year-old female who was initially treated as early-onset coxarthrosis. She later presented to us with a displaced intra-capsular neck of left femur fracture and underwent total hip replacement. This case illustrates that causes other than osteoarthritis should be taken into consideration in patients presenting with anterior hip pain where symptoms are disproportionate to clinical and radiological findings. More advanced investigations such as MRI scan or regular follow up with plain radiographs should be performed. A delay in diagnosis can lead to secondary displacement of the femoral neck stress fracture.

  20. Expected Time to Return to Athletic Participation Following Stress Fracture in Division I Collegiate Athletes

    Jamieson, Marissa; Everson, Sonsecharae; Siegel, Courtney; Miller, Timothy Lee


    Objectives: The objective of this study was to evaluate and determine the expected time to return to athletic participation in Division I collegiate Track and Field athletes. Methods: All stress fractures diagnosed in athletes on a single Division I collegiate men’s and women’s track and field/ cross-country team were recorded over a 4-year period. Site and severity of the injury were recorded and graded based on the Kaeding-Miller Classification System for stress fractures. Time to return to full unrestricted athletic participation was recorded for each athlete and correlated with the site and severity grade of the injury. Time to return to athletic participation was also analyzed for gender differences. Results: Fifty-seven stress fractures were diagnosed in 38 athletes over a 4-year period. Thirty-seven of these injuries occurred in women; twenty in men. Mean time to return to participation in women was 13.9 weeks and 11.2 weeks in men. There were 10 athletes who sustained recurrent or multiple stress fractures. Thirty-three stress fractures occurred in the tibia, and 10 occurred in the 2nd through 4th metatarsals. Three occurred in the 5th metatarsal, 6 in the tarsal bones (2 navicular), and 5 in the pelvis. Mean times to return to athletic activity based on site of injury and with extreme outliers removed were as follows: tibia- 13.3 weeks, 2nd through 4th metatarsals- 11.7 weeks, 5th metatarsal- 11.7 weeks, tarsals- 12.1 weeks, and pelvis- 13.0 weeks. There were 31 grade 2 stress fractures, 11 grade 3 stress fractures, and two grade 5 stress fractures that occurred bilaterally in the same patient. Mean times to return to athletic participation again with extreme outliers excluded were as follows: Grade 2- 12.3 weeks, Grade 3- 14.1 weeks, and Grade 5- 17 weeks. There were no Grade 4 (displaced) stress fractures diagnosed in this cohort of patients. Conclusion: Stress injuries to bone occur frequently in track and field athletes. Based on data collected

  1. Chemical and Mechanical Alteration of Fractures: Micro-Scale Simulations and Comparison to Experimental Results

    Ameli, P.; Detwiler, R. L.; Elkhoury, J. E.; Morris, J. P.


    Fractures are often the main pathways for subsurface fluid flow especially in rocks with low matrix porosity. Therefore, the hydro-mechanical properties of fractures are of fundamental concern for subsurface CO2 sequestration, enhanced geothermal energy production, enhanced oil recovery, and nuclear waste disposal. Chemical and mechanical stresses induced during these applications may lead to significant alteration of the hydro-mechanical properties of fractures. Laboratory experiments aimed at understanding the chemo-hydro-mechanical response of fractures have shown a range of results that contradict simple conceptual models. For example, under conditions favoring mineral dissolution, where one would expect an overall increase in permeability and fracture aperture, permeability increases under some conditions and decreases under others. Recent experiments have attempted to link these core-scale observations to the relevant small-scale processes occurring within fractures. Results suggest that the loss of mechanical strength in asperities due to chemical alteration may cause non-uniform deformation and alteration of fracture apertures. However, it remains difficult to directly measure the coupled chemical and mechanical processes that lead to alteration of contacting fracture surfaces, which challenges our ability to predict the long-term evolution of the hydro-mechanical properties of fractures. Here, we present a computational model that uses micro-scale surface roughness and explicitly couples dissolution and elastic deformation to calculate local alterations in fracture aperture under chemical and mechanical stresses. Chemical alteration of the fracture surfaces is modeled using a depth-averaged algorithm of fracture flow and reactive transport. Then, we deform the resulting altered fracture-surfaces using an algorithm that calculates the elastic deformation. Nonuniform dissolution may cause the location of the resultant force between the two contacting

  2. Results of open tibial fracture treatment using external fixation

    Golubović Ivan


    Full Text Available Introduction. Open lower leg fractures are the most common open fractures of the locomotor system and their treatment is associated with a number of complications. Objective. The aim of the paper was to present the results of the treatment of 68 patients with open lower leg fractures, as well as the complications that accompany the treatment of these fractures. Methods. In the analyzed group, there were 45 (66.18% men and 23 (33.82% women. The majority of patients - 33 (48.53% of them - were injured in motor vehicle accidents, whereas 24 (35.29% patients sustained injuries due to falls from heights. In two (2.94% patients the cause of open tibial fractures was gunshot injuries. In the analyzed group, there were 18 (26.47% type I open fractures, 21 (30.88% type II open fractures, 19 (27.94% type IIIA open fractures, seven (10.29% type IIIB open fractures, and three (4.41% type IIIC open fractures. Results. The tibial shaft fracture healed without serious complications in 50 (73.53% patients, whereas in 18 (26.47% patients we observed some complications. Nonunion was found in 10 (14.71% patients, osteitis in four (5.88, malunion in two (2.94% patients. Milder complications such as soft tissue pin tract infection developed in 13 (19.12% patients, infection of the open fracture wound soft tissue was observed in four (5.88% patients. Conclusion. Basic principles in the treatment of open lower leg fractures in this study are thorough primary open fracture wound treatment followed by the delayed wound closure, stable fracture fixation using unilateral external skeletal device, proper antibiotic treatment and tetanus prophylaxis. The results correlate with similar studies. [Projekat Ministarstva nauke Republike Srbije, br. III 41017: Virtual Human Osteoarticular System and its Application in Preclinical and Clinical Practice

  3. SUPERPOSE-An excel visual basic program for fracture modeling based on the stress superposition method

    Ismail Ozkaya, Sait


    An Excel Visual Basic program, SUPERPOSE, is presented to predict the distribution, relative size and strike of tensile and shear fractures on anticlinal structures. The program is based on the concept of stress superposition; addition of curvature-related local tensile stress and regional far-field stress. The method accurately predicts fractures on many Middle East Oil Fields that were formed under a strike slip regime as duplexes, flower structures or inverted structures. The program operates on the Excel platform. The program reads the parameters and structural grid data from an Excel template and writes the results to the same template. The program has two routines to import structural grid data in the Eclipse and Zmap formats. The platform of SUPERPOSE is a single layer structural grid of a given cell size (e.g. 50×50 m). In the final output, a single tensile or two conjugate shear fractures are placed in each cell if fracturing criteria are satisfied; otherwise the cell is left blank. Strike of the representative fracture(s) is calculated and exact, but the length is an index of fracture porosity (fracture density×length×aperture) within that cell.

  4. Dietary and training predictors of stress fractures in female runners.

    Wentz, Laurel; Liu, Pei-Yang; Ilich, Jasminka Z; Haymes, Emily M


    To compare female runners with and without a history of stress fractures to determine possible predictors of such fractures. 27 female runners (age 18-40 yr) who had had at least 1 stress fracture were matched to a control sample of 32 female runners without a history of stress fractures. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (iDXA). Subjects answered questionnaires on stress-fracture history, training, menstrual status, and diet. No significant differences were found in menstrual characteristics, diet and dairy intake, or bone measurements. Weekly servings of milk during middle school significantly predicted BMD at the femur (p = .010), femoral neck (p = .002), Ward's triangle (p = .014), and femoral shaft (p = .005). Number of menstrual cycles in the previous year predicted femoral-neck BMD (p = .004). Caffeine intake was negatively associated with BMD of the femur (p = .010), femoral neck (p = .003), trochanter (p = .038), and femoral shaft (p = .035). Weekly hours of training were negatively associated with total-body BMD (p = .021), total-body bone mineral content (p = .028), and lumbar-spine BMD (p = .011). Predictors for stress fractures included the number of years running, predominantly running on hard ground, irregular menstrual history, low total-body BMD, and low current dietary calcium intake when controlling for body-mass index (Nagelkerke R2 = .364). Servings of milk during middle-school years were positively correlated with hip BMD, although current calcium intake, low BMD, irregular menstrual history, hard training surface, and long history of training duration were the most important predictors of stress fractures.

  5. Some effects of stress, friction and fluid flow on hydraulic fracturing

    Hanson, M.E.; Anderson, G.D.; Shaffer, R.J.; Thorson, L.D.


    We are conducting a DOE funded research program which is aimed at understanding the hydraulic fracturing process, especially those phenomena and parameters which strongly affect or control the fracture geometry. Our theoretical and experimental studies consistently confirm the well known fact that in-situ stress has a primary effect on fracture geometry and that fractures propagate perpendicular to the least principal stress. In addition, we find that frictional interfaces in reservoirs can affect fracturing. We have also quantified some of the effects on fracture geometry due to frictional slippage along interfaces. We found that variation of friction along an interface can result in abrupt steps in the fracture path. These effects have been seen in the mine back of emplaced fractures and are demonstrated both theoretically and in the laboratory. Further experiments and calculations are starting to indicate the possible control of the fracture height by the vertical change in the cables to X-608A wells should be replaced, and develop v across categories of persons affected. Respondents were selected according to a purposive sampling strategy, wn are also included. The management plan for the operation of the plant is discussed. (DMC)

  6. Early results and future challenges of the Danish Fracture Database

    Gromov, K.; Brix, Michael; Kallemose, T.


    (currently 15,000). 85% of all procedures were performed on adult fractures and 15% on paediatric fractures. Proximal femur (33%), distal radius (15%) and malleolar fractures (12%) were the three most common primary adult fractures. Pain and discomfort from orthopaedic hardware, infection and failure......INTRODUCTION: The Danish Fracture Database (DFDB) was established in 2011 to establish nationwide prospective quality assessment of all fracture-related surgery. In this paper, we describe the DFDB's setup, present preliminary data from the first annual report and discuss its future potential...... are registered. Indication for reoperation is also recorded. The reoperation rate and the one-year mortality are the primary indicators of quality. RESULTS: Approximately 10,000 fracture-related surgical procedures were registered in the database at the time of presentation of the first annual DFDB report...

  7. kISMET: Stress and fracture characterization in a deep mine

    Oldenburg, C. M.; Dobson, P. F.; Daley, T. M.; Birkholzer, J. T.; Cook, P. J.; Ajo Franklin, J. B.; Rutqvist, J.; Siler, D.; Kneafsey, T. J.; Nakagawa, S.; Wu, Y.; Guglielmi, Y.; Ulrich, C.; Marchesini, P.; Wang, H. F.; Haimson, B. C.; Sone, H.; Vigilante, P.; Roggenthen, W.; Doe, T.; Lee, M.; Mattson, E.; Huang, H.; Johnson, T. C.; Morris, J.; White, J. A.; Johnson, P. A.; Coblentz, D. D.; Heise, J.


    We are developing a community facility called kISMET (permeability (k) and Induced Seismicity Management for Energy Technologies) at the Sanford Underground Research Facility (SURF) in Lead, SD. The purpose of kISMET is to investigate stress and the effects of rock fabric on hydraulic fracturing. Although findings from kISMET may have broad applications that inform stress and fracturing in anisotropic rock, results will be most applicable to improving control of hydraulic fracturing for enhanced geothermal systems (EGS) in crystalline rock. At the kISMET site on the 4850 ft (1480 m depth) level of SURF, we have drilled and cored an array of nearly vertical boreholes in Precambrian phyllite. The array consists of four 50-m deep monitoring boreholes surrounding one 100-m deep borehole forming a 6 m-wide five-spot pattern at a depth of 1530 m. Previous investigations of the stress field at SURF suggest that the principal stress s1 is nearly vertical. By aligning the kISMET boreholes approximately with σ1, fractures created in the center borehole should in theory be perpendicular to σ3, the least principal horizontal stress. But the phyllite at kISMET has a strong fabric (foliation) that could influence fracturing. Stress measurements and stimulation using hydraulic fracturing will be carried out in the center borehole using a straddle packer and high-pressure pump. We will use an impression packer and image logs after stress testing and stimulation to determine fracture orientation and extent at the center borehole. In order to study the control of stress, rock fabric, and stimulation approach on size, aperture, and orientation of hydraulic fractures, we will carefully monitor the stress measurements and stimulation. For example, we will use continuous active source seismic (CASSM) in two of the monitoring boreholes to measure changes in seismic-wave velocity as water fills the fracture. Second, near real-time electrical resistance tomography (ERT) will be used in

  8. Postpartum osteoporosis associated with proximal tibial stress fracture

    Clemetson, I.A.; Anderson, S.E. [Department of Radiology, University Hospital of Bern, Inselspital, 3010, Bern (Switzerland); Popp, A.; Lippuner, K. [Department of Osteology, University Hospital of Bern, Inselspital, 3010, Bern (Switzerland); Ballmer, F. [Knee and Sports Medicine Unit, Lindenhofspital Bern, 3012, Bern (Switzerland)


    A 33-year-old woman presented with acute nonspecific knee pain, 6 months postpartum. MR imaging, computed tomography and radiography were performed and a proximal tibia plateau insufficiency fracture was detected. Bone densitometry demonstrated mild postpartum osteoporosis. To our knowledge these findings have not been described in this location and in this clinical setting. The etiology of the atraumatic fracture of the tibia is presumed to be due to a low bone mineral density. The bone loss was probably due to pregnancy, lactation and postpartum hormonal changes. There were no other inciting causes and the patient was normocalcemic. We discuss the presence of a postpartum stress fracture in a hitherto undescribed site in a patient who had lactated following an uncomplicated pregnancy and had no other identifiable cause for a stress fracture. (orig.)

  9. Marrow changes in anorexia nervosa masking the presence of stress fractures on MR imaging

    Tins, B.; Cassar-Pullicino, V. [Department of Radiology, RJAH Orthopaedic and District Hospital, Oswestry (United Kingdom)


    Patients with anorexia nervosa (AN) usually have abnormal bone and bone marrow metabolism resulting in osteopenia and serous bone marrow change. There is an increased risk of stress/insufficiency fractures and these can be the first presentation of AN. This case report describes a patient with previously undiagnosed AN who presented with foot pain. The serous bone marrow changes of AN were found to mask the MR imaging features of stress fractures, as both had low T1w and high T2w and STIR signal intensities. Contrast enhancement was not helpful but actually masked fractures. Scintigraphy was helpful. The radiologist might be the first clinician to raise the possibility of AN and should be aware of the difficulties in diagnosing stress fractures in bones with underlying serous bone marrow change. In this severe case of AN even the heel fat pad and the fat pad in Kager's triangle had undergone serous change.

  10. Stress fracture of the proximal fibula after total knee arthroplasty.

    Vaish, Abhishek; Vaishya, Raju; Agarwal, Amit Kumar; Vijay, Vipul


    We report a rare case of proximal fibular fatigue fracture developing 14 years after total knee arthroplasty in a known case of rheumatoid arthritis. A valgus deformity of the knee can put abnormal stress on the upper fibula leading to its failure. We believe that, as the fibula acts as an important lateral strut, its disruption due to a fracture led to rapid progress of the valgus deformity of the knee in this patient.

  11. The impact of in-situ stress and outcrop-based fracture geometry on hydraulic aperture and upscaled permeability in fractured reservoirs

    Bisdom, Kevin; Bertotti, Giovanni; Nick, Hamid


    Aperture has a controlling impact on porosity and permeability and is a source of uncertainty in modeling of naturally fractured reservoirs. This uncertainty results from difficulties in accurately quantifying aperture in the subsurface and from a limited fundamental understanding of the mechanical...... explicitly, we quantify equivalent permeability, i.e. combined matrix and stress-dependent fracture flow. Fracture networks extracted from a large outcropping pavement form the basis of these models. The results show that the angle between fracture strike and σ 1 has a controlling impact on aperture...... and permeability, where hydraulic opening is maximum for an angle of 15°. At this angle, the fracture experiences a minor amount of shear displacement that allows the fracture to remain open even when fluid pressure is lower than the local normal stress. Averaging the heterogeneous aperture to scale up...

  12. Diagnostic accuracy of magnetic resonance imaging versus computed tomography in stress fractures of the lumbar spine

    Ganiyusufoglu, A.K., E-mail: [Department of Radiology, Florence Nightingale Hospital, Istanbul (Turkey); Onat, L. [Department of Radiology, Florence Nightingale Hospital, Istanbul (Turkey); Karatoprak, O.; Enercan, M.; Hamzaoglu, A. [Department of Orthopedics and Traumatology, Florence Nightingale Hospital, Istanbul (Turkey)


    Aim: To compare the diagnostic accuracy of magnetic resonance imaging (MRI) with computed tomography (CT) in stress fractures of the lumbar spine. Materials and methods: Radiological and clinical data from 57 adolescents and young adults with a diagnosis of stress injury of the lumbar spine were retrospectively reviewed. All cases had undergone both 1.5 T MRI and 16-section CT examinations. All MRI and CT images were retrospectively reviewed and evaluated in separate sessions. The fracture morphology (complete/incomplete, localization) and vertebral levels were noted at both the CT and MRI examinations. Bone marrow/peri-osseous soft-tissue oedema was also determined at MRI. Results: In total, 73 complete and 32 incomplete stress fractures were detected with CT. Sixty-seven complete, 24 incomplete fractures and eight stress reactions were detected using MRI in the same study group. Marrow oedema was also seen in eight of the complete and 20 of the incomplete fractures. The specificity, sensitivity, and accuracy of MRI in detecting fracture lines were 99.6, 86.7, and 97.2%, respectively. MRI was more accurate at the lower lumbar levels in comparison to upper lumbar levels. Conclusion: MRI has a similar diagnostic accuracy to CT in determining complete fractures with or without accompanying marrow oedema and incomplete fractures with accompanying marrow oedema, especially at the lower lumbar levels, which constitutes 94% of all fractures. At upper lumbar levels and in the incomplete fractures of the pars interarticularis with marked surrounding sclerosis, MRI has apparent limitations compared to CT imaging.

  13. Stress fracture in acetabular roof due to motocross: case report

    Alexandre de Paiva Luciano


    Full Text Available ABSTRACT One of the first steps to be taken in order to reduce sports injuries such as stress fractures is to have in-depth knowledge of the nature and extent of these pathological conditions. We present a case report of a stress fracture of the acetabular roof caused through motocross. This type of case is considered rare in the literature. The description of the clinical case is as follows. The patient was a 27-year-old male who started to have medical follow-up because of uncharacteristic pain in his left hip, which was concentrated mainly in the inguinal region of the left hip during motocross practice. After clinical investigation and complementary tests, he was diagnosed with a stress fracture of the acetabular roof.

  14. Stress fracture in acetabular roof due to motocross: case report.

    de Paiva Luciano, Alexandre; Filho, Nelson Franco


    One of the first steps to be taken in order to reduce sports injuries such as stress fractures is to have in-depth knowledge of the nature and extent of these pathological conditions. We present a case report of a stress fracture of the acetabular roof caused through motocross. This type of case is considered rare in the literature. The description of the clinical case is as follows. The patient was a 27-year-old male who started to have medical follow-up because of uncharacteristic pain in his left hip, which was concentrated mainly in the inguinal region of the left hip during motocross practice. After clinical investigation and complementary tests, he was diagnosed with a stress fracture of the acetabular roof.

  15. Bilateral stress fractures of the ulnae in a Kendo (Japanese fencing) player.

    Sujino, T; Ohe, T; Shinozuka, M


    A case of bilateral stress fractures of the ulnae in a Kendo (Japanese fencing) player is reported; the mechanism of the fractures, particularly the difference in the site of fracture between the right and left ulna, is discussed.

  16. 16-Detector multislice CT in the detection of stress fractures: a comparison with skeletal scintigraphy

    Groves, A.M. [Department of Radiology, Addenbrooke' s Hospital NHS Trust, University of Cambridge, Cambridge (United Kingdom)]. E-mail:; Cheow, H.K. [Department of Nuclear Medicine, Addenbrooke' s Hospital NHS Trust, University of Cambridge, Cambridge (United Kingdom); Balan, K.K. [Department of Nuclear Medicine, Addenbrooke' s Hospital NHS Trust, University of Cambridge, Cambridge (United Kingdom); Housden, B.A. [Department of Radiology, Addenbrooke' s Hospital NHS Trust, University of Cambridge, Cambridge (United Kingdom); Bearcroft, P.W.P. [Department of Radiology, Addenbrooke' s Hospital NHS Trust, University of Cambridge, Cambridge (United Kingdom); Dixon, A.K. [Department of Radiology, Addenbrooke' s Hospital NHS Trust, University of Cambridge, Cambridge (United Kingdom)


    AIMS: To test the hypothesis that the improved resolution afforded by 16-detector computed tomography (CT) would translate to better stress fracture detection when compared with skeletal scintigraphy. MATERIALS AND METHODS: Thirty-three cases of suspected stress fractures in 26 patients were investigated using skeletal scintigraphy and 16-detector CT performed on the same day. Planar images of the lower limbs were taken 3 h post-injection of 400 MBq {sup 99m}Tc-methylene diphosphonate ({sup 99m}Tc-MDP). {sup 99m}Tc-MDP uptake was quantified at suspected fracture sites. CT was performed using a 16-detector multisection machine employing 0.75 mm detectors and images reconstructed in 0.5 mm increments. Examinations were reported independently and discordant results were compared at follow-up. RESULTS: At initial reporting scintigraphy identified fractures in 13 of the 33 cases and CT identified four of the 33. In one case, on review of the CT images, a fracture was present in the distal fibula that was not initially identified. This resulted in eight scintigraphic-positive CT-negative discordant cases. The {sup 99m}Tc-MDP uptake was significantly lower in the discordant fracture group compared with the concordant group (p<0.01). CONCLUSIONS: Despite technological advances in CT, scintigraphy appeared to detect more stress fractures. As such, multidetector CT should not be used as a routine initial investigation in stress fracture detection. The potential use of {sup 99m}Tc-MDP quantification at fracture sites is of interest and may be worth further investigation.

  17. The impact of different aperture distribution models and critical stress criteria on equivalent permeability in fractured rocks

    Bisdom, Kevin; Bertotti, Giovanni; Nick, Hamidreza M.


    Predicting equivalent permeability in fractured reservoirs requires an understanding of the fracture network geometry and apertures. There are different methods for defining aperture, based on outcrop observations (power law scaling), fundamental mechanics (sublinear length-aperture scaling), and experiments (Barton-Bandis conductive shearing). Each method predicts heterogeneous apertures, even along single fractures (i.e., intrafracture variations), but most fractured reservoir models imply constant apertures for single fractures. We compare the relative differences in aperture and permeability predicted by three aperture methods, where permeability is modeled in explicit fracture networks with coupled fracture-matrix flow. Aperture varies along single fractures, and geomechanical relations are used to identify which fractures are critically stressed. The aperture models are applied to real-world large-scale fracture networks. (Sub)linear length scaling predicts the largest average aperture and equivalent permeability. Barton-Bandis aperture is smaller, predicting on average a sixfold increase compared to matrix permeability. Application of critical stress criteria results in a decrease in the fraction of open fractures. For the applied stress conditions, Coulomb predicts that 50% of the network is critically stressed, compared to 80% for Barton-Bandis peak shear. The impact of the fracture network on equivalent permeability depends on the matrix hydraulic properties, as in a low-permeable matrix, intrafracture connectivity, i.e., the opening along a single fracture, controls equivalent permeability, whereas for a more permeable matrix, absolute apertures have a larger impact. Quantification of fracture flow regimes using only the ratio of fracture versus matrix permeability is insufficient, as these regimes also depend on aperture variations within fractures.

  18. Simulating the hydraulic stimulation of multiple fractures in an anisotropic stress field applying the discrete element method

    Zeeb, Conny; Frühwirt, Thomas; Konietzky, Heinz


    Key to a successful exploitation of deep geothermal reservoirs in a petrothermal environment is the hydraulic stimulation of the host rock to increase permeability. The presented research investigates the fracture propagation and interaction during hydraulic stimulation of multiple fractures in a highly anisotropic stress field. The presented work was conducted within the framework of the OPTIRISS project, which is a cooperation of industry partners and universities in Thuringia and Saxony (Federal States of Germany) and was funded by the European Fond for Regional Development. One objective was the design optimization of the subsurface geothermal heat exchanger (SGHE) by means of numerical simulations. The presented simulations were conducted applying 3DEC (Itasca™), a software tool based on the discrete element method. The simulation results indicate that the main direction of fracture propagation is towards lower stresses and thus towards the biosphere. Therefore, barriers might be necessary to limit fracture propagation to the designated geological formation. Moreover, the hydraulic stimulation significantly alters the stresses in the vicinity of newly created fractures. Especially the change of the minimum stress component affects the hydraulic stimulation of subsequent fractures, which are deflected away from the previously stimulated fractures. This fracture deflection can render it impossible to connect all fractures with a second borehole for the later production. The results of continuative simulations indicate that a fracture deflection cannot be avoided completely. Therefore, the stage alignment was modified to minimize fracture deflection by varying (1) the pauses between stages, (2) the spacing's between adjacent stages, and (3) the angle between stimulation borehole and minimum stress component. An optimum SGHE design, which implies that all stimulated fractures are connected to the production borehole, can be achieved by aligning the stimulation

  19. Effect of stress sensitivity on displacement efficiency in CO2 flooding for fractured low permeability reservoirs

    Wang Rui; Yue Xiangan; Zhao Renbao; Yan Pingxiang; Dave Freeman


    Carbon dioxide flooding is an effective means of enhanced oil recovery for low permeability reservoirs. If fractures are present in the reservoir, CO2 may flow along the fractures, resulting in low gas displacement efficiency. Reservoir pore pressure will fluctuate to some extent during a CO2 flood, causing a change in effective confining pressure. The result is rock deformation and a reduction in permeability with the reduction in fracture permeability, causing increased flow resistance in the fracture space. Simultaneously, gas cross flowing along the fractures is partially restrained. In this work, the effect of stress changes on permeability was studied through a series of flow experiments. The change in the flowrate distribution in a matrix block and contained fracture with an increase in effective pressure were analyzed. The results lead to an implicit comparison which shows that permeability of fractured core decreases sharply with an increase in effective confining pressure. The fracture flowrate ratio declines and the matrix flowrate ratio increases. Fracture flow will partially divert to the matrix block with the increase in effective confining pressure, improving gas displacement efficiency.

  20. Bilateral stress fractures of femoral neck in non-athletes: a report of four cases

    Naik Monappa A


    Full Text Available 【Abstract】Femoral neck stress fractures (FNSFs are rare, constituting only 5% of all stress fractures in young adults. These fractures are usually seen in athletes, military recruits and patients with underlying metabolic diseases. The treatment of FNSFs is still controversial because of the inherent complications associated with the treatment procedure. We came across 4 cases of bilateral FNSFs in non-athletic individuals who were manual labourers with-out underlying bony disorders. Two patients with FNSFs and coxa vara deformity on both sides were managed by subtrochanteric valgus osteotomy and dynamic hip screw fixation. One of the remaining two patients was treated by cannulated cancellous screw fixation on one side and sub-trochanteric valgus osteotomy on the other side. The fourth patient received subtrochanteric valgus osteotomy on one side and bipolar hemiarthroplasty on the other side after failed cannulated screw fixation. All the fractures healed without any complications. No evidence of avascular ne-crosis or arthritis was noted in our series. Subtrochanteric valgus osteotomy restores normal neck-shaft angle in pa-tients suffering from FNSFs combined with coxa vara deformity. Moreover, it helps to bring the forces acting around the hip to normal biomechanical levels, leading to fracture union and better results. Replacement arthroplasty is recommended to patients who fail to achieve bony union after fixation. Key words: Fractures, stress; Femoral neck fractures; Coxa vara; Osteotomy

  1. Clinical analysis of the rap stress stimulator applied for crus fracture after skeletal external fixation

    Zhuang, Ping; Hong, Jiayuan; Chen, Wei; Wu, Jin; Ding, Zhenqi


    Introduction Open crus fracture is still difficult in clinical treatment because of the delayed fracture union and high rate of nonunion after the operation. A consensus has been reached that mechanical stress can promote fracture healing. We independently developed a stress stimulator, which can provide longitudinal pressure for the fixed fracture end of the lower legs to promote fracture healing. The purpose of this study is to explore the advantages and clinical effect of the rap stress st...

  2. Thermoelastic stresses induced by non-isothermal fluid injection into fractured rock

    Mossop, A.; Matthai, S. K.


    The injection of cold water into hot fractured rock occurs in a number of industrial scenarios, most commonly in the recharge of geothermal reservoirs and during waterflood operations in hydrocarbon reservoirs. The cold water cools the rock local to the fracture flow pathways, the cooled rock contracts, causing localised stress perturbations. Essentially analogous physical processes are involved in the injection of hot fluids into cooler rock such as occur in steam flood operations in viscous oil recovery. In this study we investigate such thermoelastic stresses induced by non-isothermal injection into a three dimensional fractured rock mass. The starting point of our analysis is an idealized model of injection into a single, uniform, horizontal fracture. For this case we have previously found semi-analytic solutions and analytic estimates of the stress perturbation and these are in turn used for cross-verification of an isoparametric, quadratic, finite element model of the system. In the numerical model the fractures are treated as discrete conductive channels within the matrix and an additional feature is that the matrix itself can be assigned a non-zero permeability. As the numerical simulator follows a fundamentally different methodology for solving these thermoelastic problems, the results help to validate some of the scaling relationships and non-intuitive behaviour deduced from the analytic estimates (e.g. for a broad range of flow rates, fracture normal stress perturbations decrease with increasing injection rates). The finite element model is then used to explore progressively more complex fracture geometries and networks. Finally we investigate the validity of a continuum limit as fracture densities increase to the point that fracture separation length scales are comparable with thermal diffusion length scales.

  3. Creep and Fracture of a Protein Gel under Stress

    Leocmach, Mathieu; Perge, Christophe; Divoux, Thibaut; Manneville, Sébastien


    Biomaterials such as protein or polysaccharide gels are known to behave qualitatively as soft solids and to rupture under an external load. Combining optical and ultrasonic imaging to shear rheology we show that the failure scenario of a protein gel is reminiscent of brittle solids: after a primary creep regime characterized by a power-law behavior whose exponent is fully accounted for by linear viscoelasticity, fractures nucleate and grow logarithmically perpendicularly to shear, up to the sudden rupture of the gel. A single equation accounting for those two successive processes nicely captures the full rheological response. The failure time follows a decreasing power law with the applied shear stress, similar to the Basquin law of fatigue for solids. These results are in excellent agreement with recent fiber-bundle models that include damage accumulation on elastic fibers and exemplify protein gels as model, brittlelike soft solids.

  4. Stress Fracture of the Ulna in an Elite Ice Dancer

    Davide Tornese


    Full Text Available Stress fracture of the ulna is a rare overuse injury often arising from repetitive excessive forearm rotation. Here we report the first case of ulnar stress fracture in a female ice dancer. Diagnosis was made by history and physical examination, with the aid of imaging studies (plain x-ray, computed tomography, and magnetic resonance imaging, and biomechanical analysis of forearm pronation and supination. Following identification and modification of the causal technical element, the ice dancer was able to continue training and competing without cessation of activity. Treatment was with a 30-day course of capacitively coupled bone stimulation to promote fracture healing, confirmed on radiography and magnetic resonance imaging. Such injuries to ice dancers may be prevented at the planning stage of technical elements in the dance program if coaches place more attention on the potentially deleterious effects of difficult positions the lifted dancer must sustain to reward points on the technical elements score.

  5. Micromechanical studies of cyclic creep fracture under stress controlled loading

    van der Giessen, Erik; Tvergaard, Viggo


    This paper deals with a study of intergranular failure by creep cavitation under stress-controlled cyclic loading conditions. Loading is assumed to be slow enough that diffusion and creep mechanisms (including grain boundary sliding) dominate, leading to intergranular creep fracture. This study i...

  6. An Unusual Stress Fracture in an Archer with Hypophosphatasia

    Umut Yavuz


    Full Text Available We report a 45-year-old male archer with stress fracture in his left ulna on the background of adult type of hypophosphatasia. The patient presented to several medical centers for pain around the left elbow and received medical treatment upon diagnosis of tenosynovitis. History of the patient revealed that he had had diagnosis of hypophosphatasia ten years ago and underwent percutaneous screwing for stress fracture on both of his femoral necks. Upon finding nondisplaced stress fracture on proximal metaphysis of the ulna on X-ray, the patient underwent magnetic resonance imaging (MRI in order to exclude pathological causes. No additional pathology was observed in MRI scanning. The patient’s sportive activities were restricted for 6 weeks and he received conservative management with arm slings. Adult type of hypophosphatasia is a disease manifesting with widespread osteoporosis and presenting with low serum level of alkali phosphatase (ALP. Stress fracture should definitely be considered in the patients with history of hypophosphatasia and refractory extremity pain.

  7. Micromechanical studies of cyclic creep fracture under stress- controlled loading

    Giessen, E. van der; Tvergaard, V.


    This paper deals with a study of intergranular failure by creep cavitation under stress-controlled cyclic loading conditions. Loading is assumed to be slow enough that diffusion and creep mechanisms (including grain boundary sliding) dominate, leading to intergranular creep fracture. This study is

  8. An interactive surgical planning tool for acetabular fractures: initial results

    Marincek Borut


    Full Text Available Abstract Background Acetabular fractures still are among the most challenging fractures to treat because of complex anatomy, involved surgical access to fracture sites and the relatively low incidence of these lesions. Proper evaluation and surgical planning is necessary to achieve anatomic reduction of the articular surface and stable fixation of the pelvic ring. The goal of this study was to test the feasibility of preoperative surgical planning in acetabular fractures using a new prototype planning tool based on an interactive virtual reality-style environment. Methods 7 patients (5 male and 2 female; median age 53 y (25 to 92 y with an acetabular fracture were prospectively included. Exclusion criterions were simple wall fractures, cases with anticipated surgical dislocation of the femoral head for joint debridement and accurate fracture reduction. According to the Letournel classification 4 cases had two column fractures, 2 cases had anterior column fractures and 1 case had a T-shaped fracture including a posterior wall fracture. The workflow included following steps: (1 Formation of a patient-specific bone model from preoperative computed tomography scans, (2 interactive virtual fracture reduction with visuo-haptic feedback, (3 virtual fracture fixation using common osteosynthesis implants and (4 measurement of implant position relative to landmarks. The surgeon manually contoured osteosynthesis plates preoperatively according to the virtually defined deformation. Screenshots including all measurements for the OR were available. The tool was validated comparing the preoperative planning and postoperative results by 3D-superimposition. Results Preoperative planning was feasible in all cases. In 6 of 7 cases superimposition of preoperative planning and postoperative follow-up CT showed a good to excellent correlation. In one case part of the procedure had to be changed due to impossibility of fracture reduction from an ilioinguinal approach

  9. Transferability of Charpy Absorbed Energy to Fracture Toughness Based on Weibull Stress Criterion

    Hongyang JING; Lianyong XU; Lixing HUO; Fumiyoshi Minami


    The relationship between Charpy absorbed energy and the fracture toughness by means of the (crack tip opening displacement (CTOD)) method was analyzed based on the Weibull stress criterion. The Charpy absorbed energy and the fracture toughness were measured for the SN490B steel under the ductile-brittle transition temperature region. For the instrumented Charpy impact test, the curves between the loading point displacement and the load against time were recorded. The critical Weibull stress was taken as a fracture controlled parameter, and it could not be affected by the specimen configuration and the loading pattern based on the local approach. The parameters controlled brittle fracture are obtained from the Charpy absorbed energy results, then the fracture toughness for the compact tension (CT) specimen is predicted. It is found that the results predicted are in good agreement with the experimental. The fracture toughness could be evaluated by the Charpy absorbed energy, because the local approach gives a good description for the brittle fracture even though the Charpy impact specimen or the CT specimen is used for the given material.

  10. Talar body fatigue stress fractures: three cases observed in elite female gymnasts

    Rossi, F. [National Institute of Sports Medicine of the Italian Olympic Committee, Rome (Italy); Dragoni, S. [National Institute of Sports Medicine of the Italian Olympic Committee, Rome (Italy); Istituto Nazionale di Medicina dello Sport, Rome (Italy)


    To introduce and emphasize the clinical and radiological findings of three talar body fatigue stress fractures in competitive athletes. Clinical and radiographic skeletal records of 24,562 athletes taken between 1962 and 2002 were retrospectively reviewed. Among these, 6851 files related to acute foot and ankle injuries or chronic post-traumatic sequelae were found. There were 925 (3.76%) stress fatigue fractures selected from the whole collection. Among these there were three cases (0.32%) of talar body stress fractures diagnosed in elite female gymnasts 15 - 17 years old. The negative first radiograph become positive 4-6 weeks later. Scintigraphy was positive at an early stage and consistent for the diagnosis. CT and MRI gave positive results 1-2 weeks after the beginning of symptoms which were always greatly diagnostic. The sports medicine literature lacks reports of talar body fatigue stress fractures. The poor initial sensitivity of radiography makes it problematic to establish an early diagnosis. A wise combination of scintigraphy, CT and MRI has therefore to be relied upon. Familiarity with this rare location for a stress fracture may prevent delayed diagnosis and long-lasting damage, both of which are important factors in competitive athletes. (orig.)

  11. Damage and fracture mechanism of 6063 aluminum alloy under three kinds of stress states

    ZHU Hao; ZHU Liang; CHEN Jianhong


    To study the damage and fracture mechanism of 6063 aluminum alloy under different stress states,three kinds of representative triaxial stress states have been adopted,namely smooth tensile,notch tensile,and pure shear.The results of the study indicate the following.During the notch tensile test,a relatively higher stress triaxiality appears in the root of the notch.With the applied loading increasing,the volume fraction of microvoids in the root of the notch increases continuously.When it reaches the critical volume fraction of microvoids,the specimen fractures.During the pure shear test,the stress triaxiality almost equals to zero,and there is almost no microvoids but a shear band at the center of the butterfly specimen.The shear band results from nonuniform deformation constantly under the shear stress.With stress concentration,cracks are produced within the shear band and are later coalesced.When the equivalent plastic strain reaches the critical value (equivalent plastic fracture strain),the butterfly specimen fractures.During the smooth tensile test,the stress triaxiality in the gauge of the specimen remains constant at 0.33.Thus,the volume of microvoids of the smooth tensile test is less than that of the notch tensile test and the smooth specimen fractures due to shearing between microvoids.The G-T-N damage model and Johnson-Cook model are used to simulate the notch tensile and shear test,respectively.The simulated engineering stress-strain curves fit the measured engineering stress-strain curves very well.In addition,the empirical damage evolution equation for the notch specimen is obtained from the experimental data and FEM simulations.

  12. Correlation between porous structure and fracture stress for metallurgical coke

    Gardien, J.F.; Lemaire, E.; Dubs, A.; Osmont, P.; Laurent, J.P.; Steiler, J.M. (Institut de Recherches de la Siderurgie Francaise, Maizieres-les-Metz (France))


    Various samples of coke have been characterized by diametral compression and the geometry of the porous network has been analysed in terms of fractal structure. It is found that the coke studied exhibits a fractal behaviour on at least two decades. Diametral compression test leads to two different ways of breaking; brittle fracture, and in some cases complex fracture. As expected, the fracture stress is not linked with the fractal dimension in case of brittle fracture, but with the mean size of the largest pores. In case of complex loading conditions, the fracture strength is linked with the fractal dimension. The models of Cook and of Anderson, which integrate fractal description of porous materials in Griffith's theory, do not seem to be valid concerning coke material. The present approach of characterising the porous structure of coke by the fractal dimension seems adapted to explain coke strength, especially under complex stress conditions, but should be extended to an increased number of coke type samples.

  13. Use of non-fault fractures in stress tensor reconstruction using the Mohr Circle with the Win-tensor program

    Delvaux, Damien


    stress axes can be determined and the stress ratio R (sigma 2-3)/sigma1-3) has to be pre-determined. With the combined function (F11), it provide an additional constrain to the classical angular misfit. With data sets composed of a majority of neoformed fractures, stress inversion using the Mohr Distance F10 function provide a good approximation of the 3 stress axes (using only the fracture data) as compared with the results of the F11 composite function (using also the observed slip lines). Tensor program is available at (

  14. Report of Galeazzi fracture resulting from a ballistic injury.

    Fillingham, Yale; Hellman, Michael; Haughom, Bryan; Erickson, Brandon; Szatkowski, Jan


    Galeazzi fractures are a rare injury to occur in adults, which are typically associated with high energy trauma. To our knowledge, the reported cases in the literature have only been associated with motor vehicle accidents, falls from a height, or athletic endeavors. The application of the force in the setting of a Galeazzi fracture has been disputed, but it is believed to occur with the wrist in hyperextension and pronation. We describe a 27-year-old male who presented with multiple gunshot wounds that included his right forearm. The injury sustained to his right forearm resulted in a Galeazzi fracture, which after open reduction and internal fixation, demonstrated subluxation of the distal radioulnar joint in pronation. We provide a novel mechanism of a Galeazzi fracture that demonstrates a method for sustaining the fracture pattern without the wrist in the typical position of hyperextension and pronation.

  15. A new coal-permeability model: Internal swelling stress and fracture-matrix interaction

    Liu, H.H.; Rutqvist, J.


    We have developed a new coal-permeability model for uniaxial strain and constant confining stress conditions. The model is unique in that it explicitly considers fracture-matrix interaction during coal deformation processes and is based on a newly proposed internal-swelling stress concept. This concept is used to account for the impact of matrix swelling (or shrinkage) on fracture-aperture changes resulting from partial separation of matrix blocks by fractures that do not completely cut through the whole matrix. The proposed permeability model is evaluated with data from three Valencia Canyon coalbed wells in the San Juan Basin, where increased permeability has been observed during CH{sub 4} gas production, as well as with published data from laboratory tests. Model results are generally in good agreement with observed permeability changes. The importance of fracture-matrix interaction in determining coal permeability, demonstrated in this work using relatively simple stress conditions, underscores the need for a dual-continuum (fracture and matrix) mechanical approach to rigorously capture coal-deformation processes under complex stress conditions, as well as the coupled flow and transport processes in coal seams.

  16. Atypical femoral neck stress fracture in a marathon runner: a case report and literature review.


    BACKGROUND: Femoral neck stress fractures are relatively rare and may present as sports-related injuries. The presentation is variable, and prompt diagnosis facilitates the earliest return to pre-morbid functional activity levels. Delayed detection may precipitate femoral non-union or avascular necrosis, resulting in long-term functional deficit. AIMS: We present the case of a basicervical femoral neck stress fracture occurring in a 23-year-old marathon runner. The pathophysiology and practical management issues related to this unusual injury pattern are discussed. CONCLUSION: The growing interest in amateur athletic activities should raise the index of suspicion for stress fractures of the femoral neck in healthy adults with atypical hip pain. Increased levels of patient education and physician awareness can reduce the incidence of long-term morbidity in cases of this unusual sports-related injury.

  17. Effective-stress-law behavior of Austin chalk rocks for deformation and fracture conductivity

    Warpinski, N.R.; Teufel, L.W.


    Austin chalk core has been tested to determine the effective law for deformation of the matrix material and the stress-sensitive conductivity of the natural fractures. For deformation behavior, two samples provided data on the variations of the poroelastic parameter, {alpha}, for Austin chalk, giving values around 0.4. The effective-stress-law behavior of a Saratoga limestone sample was also measured for the purpose of obtaining a comparison with a somewhat more porous carbonate rock. {alpha} for this rock was found to be near 0.9. The low {alpha} for the Austin chalk suggests that stresses in the reservoir, or around the wellbore, will not change much with changes in pore pressure, as the contribution of the fluid pressure is small. Three natural fractures from the Austin chalk were tested, but two of the fractures were very tight and probably do not contribute much to production. The third sample was highly conductive and showed some stress sensitivity with a factor of three reduction in conductivity over a net stress increase of 3000 psi. Natural fractures also showed a propensity for permanent damage when net stressed exceeded about 3000 psi. This damage was irreversible and significantly affected conductivity. {alpha} was difficult to determine and most tests were inconclusive, although the results from one sample suggested that {alpha} was near unity.

  18. Stress evolution during 3D single-layer visco-elastic buckle folding: Implications for the initiation of fractures

    Liu, Xiaolong; Eckert, Andreas; Connolly, Peter


    Buckle folds of sedimentary strata commonly feature a variety of different fracture sets. Some fracture sets including outer arc tensile fractures and inner arc shear fractures at the fold hinge zones are well understood by the extensional and compressional strain/stress pattern. However, other commonly observed fracture sets, including tensile fractures parallel to the fold axis, tensile fractures cutting through the limb, extensional faults at the fold hinge, and other shear fractures of various orientations in the fold limb, fail to be intuitively explained by the strain/stress regimes during the buckling process. To obtain a better understanding of the conditions for the initiation of the various fractures sets associated with single-layer cylindrical buckle folds, a 3D finite element modeling approach using a Maxwell visco-elastic rheology is utilized. The influences of three model parameters with significant influence on fracture initiation are considered: burial depth, viscosity, and permeability. It is concluded that these parameters are critical for the initiation of major fracture sets at the hinge zone with varying degrees. The numerical simulation results further show that the buckling process fails to explain most of the fracture sets occurring in the limb unless the process of erosional unloading as a post-fold phenomenon is considered. For fracture sets that only develop under unrealistic boundary conditions, the results demonstrate that their development is realistic for a perclinal fold geometry. In summary, a more thorough understanding of fractures sets associated with buckle folds is obtained based on the simulation of in-situ stress conditions during the structural development of buckle folds.

  19. Stress fracture injury in young military men and women.

    Armstrong, David W; Rue, John-Paul H; Wilckens, John H; Frassica, Frank J


    Approximately 5% of all military recruits incur stress fracture injuries during intense physical training, predominately in the lower extremity. We compared young men and women with stress fracture injury (subjects) to a matched group of uninjured volunteers (controls) during a summer training program at the United States Naval Academy to identify possible risk factors for stress fracture injury. The subject group was composed of 13 female and 18 male plebes with training-induced stress fracture injury verified by plain radiographs and/or nuclear bone scan. The control group was composed of 13 female and 18 male plebes who remained without injury during plebe summer training but who were matched with the 31 injured plebes for the Initial Strength Test (1-mi run time, means: women, 7.9 min; men, 6.4 min) and body mass index (means: women, 23.4; men, 23.8). We found that the subjects lost significant body weight (mean, 2.63 +/- 0.54 kg) between Day 1 and the date of their diagnosis of a stress fracture (mean, Day 35) and that they continued to lose weight until the date of their DEXA scan (mean, Day 49). Among female plebes, there was no evidence of the female athlete triad (eating disorders, menstrual dysfunction, or low bone density). Thigh girth was significantly smaller in female subjects than in female controls and trended to be lower in male subjects than in male controls. Total body bone mineral content was significantly lower in the male subjects than in male controls. Bone mineral density of the distal tibia and femoral neck were not significantly different between the groups. DEXA-derived structural geometric properties were not different between subjects and controls. Because, on average, tibias were significantly longer in male subjects than in male controls, the mean bone strength index in male subjects was significantly lower than that of male controls. We conclude that significant, acute weight loss combined with regular daily physical training among

  20. Sequential Proximal Tibial Stress Fractures associated with Prolonged usage of Methotrexate and Corticosteroids: A Case Report

    Tan TJL


    Full Text Available Stress fractures of the proximal tibia metaphysis are rare in the elderly. We present a case of a 65-year old male who developed sequential proximal tibia stress fractures associated with prolonged usage of methotrexate and prednisolone within a span of 18 months. Magnetic Resonance Imaging revealed an incomplete stress fracture involving the medial proximal tibial region. The patient was treated with stemmed total knee arthroplasty (TKA bilaterally. Stress fractures should be considered in patients with atypical knee pain who have a history of methotrexate and prednisolone usage. TKA is an effective treatment in stress fractures of the proximal tibia.

  1. Post-operative stress fractures complicating surgery for painful forefoot conditions.

    Edwards, Max R; Jack, Christopher; Jones, Gareth G; Singh, Samrendu K


    A stress fracture is caused by repetitive or unusual loading of a bone leading to mechanical failure. Fatigue type stress fractures occur in normal bone exposed to abnormally high repetitive loads, whereas insufficiency type stress fractures occur in abnormal bone exposed to normal loads. We describe three cases of insufficiency stress fractures that have complicated surgery for painful forefoot conditions. The diagnosis and management of these cases are discussed. Stress fractures should be included in the differential diagnosis of any patient who continues or develops pain after surgery to the forefoot.

  2. In-situ stress measurements and stress change monitoring to monitor overburden caving behaviour and hydraulic fracture pre-conditioning

    Puller Jesse W.; Mills Ken W.; Jeffrey Rob G.; Walker Rick J.


    A coal mine in New South Wales is longwall mining 300 m wide panels at a depth of 160–180 m directly below a 16–20 m thick conglomerate strata. As part of a strategy to use hydraulic fracturing to manage potential windblast and periodic caving hazards associated with these conglomerate strata, the in-situ stresses in the conglomerate were measured using ANZI strain cells and the overcoring method of stress relief. Changes in stress associated with abutment loading and placement of hydraulic fractures were also measured using ANZI strain cells installed from the surface and from underground. Overcore stress mea-surements have indicated that the vertical stress is the lowest principal stress so that hydraulic fractures placed ahead of mining form horizontally and so provide effective pre-conditioning to promote caving of the conglomerate strata. Monitoring of stress changes in the overburden strata during longwall retreat was undertaken at two different locations at the mine. The monitoring indicated stress changes were evi-dent 150 m ahead of the longwall face and abutment loading reached a maximum increase of about 7.5 MPa. The stresses ahead of mining change gradually with distance to the approaching longwall and in a direction consistent with the horizontal in-situ stresses. There was no evidence in the stress change monitoring results to indicate significant cyclical forward abutment loading ahead of the face. The for-ward abutment load determined from the stress change monitoring is consistent with the weight of over-burden strata overhanging the goaf indicated by subsidence monitoring.

  3. Stress- and Chemistry-Mediated Permeability Enhancement/Degradation in Stimulated Critically-Stressed Fractures

    Derek Elsworth; Abraham S. Grader; Chris Marone; Phillip Halleck; Peter Rose; Igor Faoro; Joshua Taron; André Niemeijer; Hideaki Yasuhara


    This work has investigated the interactions between stress and chemistry in controlling the evolution of permeability in stimulated fractured reservoirs through an integrated program of experimentation and modeling. Flow-through experiments on natural and artificial fractures in Coso diorite have examined the evolution of permeability under paths of mean and deviatoric stresses, including the role of dissolution and precipitation. Models accommodating these behaviors have examined the importance of incorporating the complex couplings between stress and chemistry in examining the evolution of permeability in EGS reservoirs. This document reports the findings of experiment [1,2] and analysis [3,4], in four sequential chapters.

  4. Stress fracture of the distal fibula in flatfoot patients: case report

    Cheng, Yu; Yang, Huilin; Ni, Li; Song, Dawei; Zhang, Hongtao


    The increase in proportional loading of the fibula with progression of hindfoot deformity would lead to high fibular loads during rapid walking, resulting in insufficiency fractures. We report an unusual mechanism of such fracture in a textile worker resulting from valgus alignment from a stage III flatfoot deformity. The stress fracture was missed initially and only confirmed by CT examination. The patient responded well to nonoperative treatment and had an excellent recovery with no residual symptoms finally. Fracture of the distal fibula caused by rigid hindfoot valgus in stage III flatfoot deformity is a previously undescribed injury. We report a patient who presented with this injury, the possible mechanisms of such injury, its management and outcome. PMID:26131245

  5. Anisotropy effect on the stress-based fracture forming limit diagram using a modified Lou-Huh ductile fracture criterion

    Park, Namsu; Huh, Hoon


    This paper is concerned with the anisotropy effect on the stress-based fracture forming limit diagram using a modified Lou-Huh ductile fracture criterion. In sheet metal forming process, a usage of advanced high-strength steels (AHSSs) has been remarkably increasing for the lightweight car body and good formability. It is, however, unable to evaluate the formability of AHSS with the conventional forming limit diagram during complex forming processes since it is obtained by assuming the proportional loading path and AHSS shows sudden fracture involving little amount of necking. The stress-based fracture forming limit diagram was constructed using a modified Lou-Huh ductile fracture criterion in order to evaluate the formability of AHSS accurately. The anisotropy effect on the fracture strain is also evaluated to reflect the material behavior of sheet metals in constructing the criterion for the prediction of onset of the fracture. The constructed stress-based fracture forming limit diagrams deal with the stress state ranging from pure shear to equi-biaxial tension with the variation of orientation of sheet metals. It is clearly observed that the stress-based fracture forming limit diagrams are varied with the change of orientation of sheet metals.

  6. [Stress reactions--stress fracture of the upper femoral neck in endurance sports].

    Schultz, W; Stinus, H; Schleicher, W; Hess, T


    Stress reactions of the musculoskeletal system may be interpreted as possible precursors of stress fractures. Biological material, in contrast to artificial products, can react in numerous and complex ways. This can not only lead to a continual weakening of the tissue, but also to adaptation phenomena in response to overuse. The causes of such stress reactions are still unclear in many respects. For example, it is unknown to what extent a predisposition to these stress symptoms is created by mechanical stress alone or whether other factors such as physical condition, nutrition or even hormone balance come into play. Early diagnosis considerably reduces the healing process and, the later the diagnosis of the stress reaction, the more drawn out is the healing process and the extent of the athlete's absence from training. In this connection may be discussed whether the stress reaction can be the represent as the precursor of the stress fracture. In light of the need for taking special care in obtaining anamnestic data and determining the predisposition of an athlete, it appears to be justified to perform whole body bone scanning in the initial stages and particularly after an innocuous radiological finding. To what extent more current methods (e. g. MRI) can be applied without exposing the athlete to undue radiation cannot be conclusively judged at present. The treatment of a stress reaction should, at least at the beginning, be the same as for a diagnosed stress fracture.

  7. Maximum twin shear stress factor criterion for sliding mode fracture initiation

    黎振兹; 李慧剑; 黎晓峰; 周洪彬; 郝圣旺


    Previous researches on the mixed mode fracture initiation criteria were mostly focused on opening mode fracture. In this study, the authors proposed a new criterion for mixed mode sliding fracture initiation, which is the maximum twin shear stress factor criterion. The authors studied a finite width plate with central slant crack, subject to a far-field uniform uniaxial tensile or compressive stress.

  8. Stresses and Shear Fracture Zone of Jinshazhou Tunnel Surrounding Rock in Rich Water Region

    ZHENG Jun-jie; LOU Xiao-ming


    Field evidence has shown that large-scale and unstable discontinuous planes in the rock mass surrounding tunnels in rich water region are probably generated after excavation. The tunnel surrounding rock was divided into three zones, including elastic zone, plastic damage zone and shear fracture zone fof assessing the stability of the tunnel surrounding rock. By local hydrogeology, the stresses of surrounding rock of Jinshazhou circular tunnel was analyzed and the stress solutions on the elastic and plastic damage zones were obtained by applying the theories of fluid-solid coupling and elasto-plastic damage mechanics. The shear fracture zone generated by joints was studied and its range was determined by using Mohr-Coulomb strength criterion. Finally, the correctness of the theoretical results was validated by comparing the scopes of shear fracture zones calculated in this paper with those from literature.

  9. [Bilateral stress fracture of the mid-tibial shaft in a professional dancer].

    Tomčovčík, L; Tomčovčíková, A


    Stress fractures of the anterior cortex of the mid-tibial shaft in dancers are rare, with a 1.4 % incidence in injured eli- te dancers. Treatment can be difficult and long-lasting and can seriously influence the dancer's career. The authors pre- sent the case of a 26-year-old professional dancer of a folk dance ensemble who suffered rare simultaneous bilateral mid-tibial shaft stress fractures. A conservative method of treatment with avoiding exercise and dancing activities resulted in the resolution of symptoms and healing of the fractures after 6 months. The patient finished his dancing career because of the necessity of a prolonged therapy interfering with his dancing activities. Current options of the treatment are also presented.

  10. Misdiagnosis of sacral stress fracture: an underestimated cause of low back pain in pregnancy?

    Deschamps Perdomo, Ambar; Tome-Bermejo, Felix; Piñera, Angel R; Alvarez, Luis


    Sacral stress fracture during pregnancy is an uncommon condition with unclear pathophysiology, presenting with non-specific symptoms and clinical findings. To date, few cases have been published in the literature describing the occurrence of sacral stress fracture during pregnancy. We report a 28-year-old primigravid patient who developed lumbosacral pain at the end of the second trimester. Symptoms were overlooked throughout pregnancy and the postpartum period, resulting in the development of secondary chronic gait and balance problems. Stress fracture of the sacrum should be included in the differential diagnosis of low back and sacral pain during pregnancy. Its prevalence is probably underestimated because of the lack of specificity of the symptoms. Plain radiographs are not appropriate due to radiation exclusion; magnetic resonance is the only method that can be applied safely. There is limited information on natural history but many patients are expected to have a benign course. However, misdiagnosis may lead to prolonged morbidity and the development of secondary gait abnormalities. Stress fracture of the sacrum should be included in the differential diagnosis of low back and sacral pain during pregnancy. A high index of suspicion is necessary to establish an early diagnosis and appropriate treatment.

  11. Analysis of the results of different types of diaphyseal tibial fractures with intraosseous and of plate osteosynthesis

    V. V. Pisarev


    Full Text Available Aim of this study - comparative assesment of treatment outcomes of different types of diaphyseal shin fractures in patients with bone and intraosteal lackable osteosynthesis. Material and methods. We examined 222 patients with fused diaphyseal shin fractures. In 122 patients close reduction and intraosteal lackable osteosynthesis of shin bones was performed, in 100 - open reduction and osteosynthesis of shin bones with plates LCDCP All patients were divided into subgroups according to АО/ASIF classification (fractures type А, В, С. The evaluation of the results was done in two years period after surgery with questionnaire SF36, outpatients clinic cards analysis, CITO cards study outcomes of fractures, rheovasography and X-ray examination. Results. We found that in patients with fractures types A and В these two types of osteosynthesis lead to similar results according to questionnaire SF36, comparable with control group. Bone osteosynthesis in treatment of fractures type С results in higher quality of life, comparable with control group, than intraosteal. Indicators of treatment outcomes in accordance with CITO card in bone osteosynthesis were higher than in intraosteal. In bone osteosynthesis of fractures type A the terms of temporary disability and fusion significantly lower than in intraosteal osteosynthesis of the similar fractures. Reduce of the tolerance to heavy physical stress in patients with fractures type С in intraosteal osteosynthesis determined by low blood flow in shin. Treatment of shin fractures with bone and intraosteal osteosynthesis follows by equal risks of complications.

  12. Lower limb stress fractures in sport: Optimising their management and outcome

    Robertson, Greg A J; Wood, Alexander M


    Stress fractures in sport are becoming increasing more common, comprising up to 10% of all of sporting injuries. Around 90% of such injuries are located in the lower limb. This articles aims to define the optimal management of lower limb stress fractures in the athlete, with a view to maximise return rates and minimise return times to sport. Treatment planning of this condition is specific to the location of the injury. However, there remains a clear division of stress fractures by “high” and “low” risk. “Low risk” stress fractures are those with a low probability of fracture propagation, delayed union, or non-union, and so can be managed reliably with rest and exercise limitation. These include stress fractures of the Postero-Medial Tibial Diaphysis, Metatarsal Shafts, Distal Fibula, Medial Femoral Neck, Femoral Shaft and Calcaneus. “High risk” stress fractures, in contrast, have increased rates of fracture propagation, displacement, delayed and non-union, and so require immediate cessation of activity, with orthopaedic referral, to assess the need for surgical intervention. These include stress fractures of the Anterior Tibial Diaphysis, Fifth Metatarsal Base, Medial Malleolus, Lateral Femoral Neck, Tarsal Navicular and Great Toe Sesamoids. In order to establish the optimal methods for managing these injuries, we present and review the current evidence which guides the treatment of stress fractures in athletes. From this, we note an increased role for surgical management of certain high risk stress fractures to improve return times and rates to sport. Following this, key recommendations are provided for the management of the common stress fracture types seen in the athlete. Five case reports are also presented to illustrate the application of sport-focussed lower limb stress fracture treatment in the clinical setting. PMID:28361017

  13. Stress fractures of ankle and wrist in childhood: nature and frequency

    Oestreich, Alan E. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); Bhojwani, Nicholas [University of Cincinnati College of Medicine, Cincinnati, OH (United States)


    Stress fractures of many etiologies are found not infrequently in various tarsal bones but are less commonly recognized in carpal bones. To assess the distribution of tarsal and carpal stress fractures. During the last three decades, the senior author collected locations of tarsal and carpal bone stress fracture callus seen on plain radiographs. 527 children with tarsal and carpal stress fractures were identified (88 children had multiple bones involved). The totals were: calcaneus 244, cuboid 188, talus 121, navicular 24, cuneiforms 23, capitate 18, lunate 1, and scaphoid 1. Stress fractures were more frequently seen once we became aware each particular bone could be involved. Tarsal and carpal stress fractures in children are not rare. Careful perusal of these bones is urged in all susceptible children with limping or wrist pain. (orig.)

  14. Bilateral stress fractures of femoral neck in non-athletes:a report of four cases

    Monappa A Naik; Premjit Sujir; Sujit Kumar Tripathy; Sandeep Vijayan; Shamsi Hameed; Sharath K Rao


    Femoral neck stress fractures (FNSFs) are rare,constituting only 5% of all stress fractures in young adults.These fractures are usually seen in athletes,military recruits and patients with underlying metabolic diseases.The treatment of FNSFs is still controversial because of the inherent complications associated with the treatment procedure.We came across 4 cases of bilateral FNSFs in non-athletic individuals who were manual labourers without underlying bony disorders.Two patients with FNSFs and coxa vara deformity on both sides were managed by subtrochanteric valgus osteotomy and dynamic hip screw fixation.One of the remaining two patients was treated by cannulated cancellous screw fixation on one side and subtrochanteric valgus osteotomy on the other side.The fourth patient received subtrochanteric valgus osteotomy on one side and bipolar hemiarthroplasty on the other side after failed cannulated screw fixation.All the fractures healed without any complications.No evidence of avascular necrosis or arthritis was noted in our series.Subtrochanteric valgus osteotomy restores normal neck-shaft angle in patients suffering from FNSFs combined with coxa vara deformity.Moreover,it helps to bring the forces acting around the hip to normal biomechanical levels,leading to fracture union and better results.Replacement arthroplasty is recommended to patients who fail to achieve bony union after fixation.

  15. On the fracture of human dentin: Is it stress- orstrain-controlled?

    Nalla, R.K.; Kinney, J.H.; Ritchie, R.O.


    Despite substantial clinical interest in the fracture resistance of human dentin, there is little mechanistic information in archival literature that can be usefully used to model such fracture. In fact, although the fracture event indent in, akin to other mineralized tissues like bone, is widely believed to be locally strain-controlled, there has never been any scientific proof to support this belief. The present study seeks to address this issue through the use of a novel set of in vitro experiments in Hanks' balanced salt solution involving a double-notched bend test geometry, which is designed to discern whether the critical failure events involved in the onset of fracture are locally stress- or strain-controlled. Such experiments are further used to characterize the notion of ''plasticity'' in dentin and the interaction of cracks with the salient microstructural features. It is observed that fracture in dentin is indeed locally strain-controlled and that the presence of dentinal tubules does not substantially affect this process of crack initiation and growth. The results presented are believed to be critical steps in the development of a micromechanical model for the fracture of human dentin that takes into consideration the influence of both the microstructure and the local failure mode.

  16. Permeability Enhancement in Enhanced Geothermal System as a result of Hydraulic Fracturing and Jacking

    Jalali, Mohammadreza; Klepikova, Maria; Fisch, Hansruedi; Amann, Florian; Loew, Simon


    A decameter-scale in-situ hydraulic stimulation and circulation (ISC) experiment has been initiated by the newly-founded Swiss Competence Centre for Energy Research - Supply of Electricity (SCCER-SoE) at Nagra's Grimsel Test Site (GTS) as a part of the work-package WP1 of the Deep Underground Laboratory (DUG-Lab) initiative. The experiment area is situated in the southern part of the GTS in a low fracture density volume of the Grimsel granodiorite. The hydraulic properties of the granitic rock mass are supposed to be similar to those expected in the crystalline basement of the alpine foreland where deep enhanced geothermal systems might be developed in future. The main objectives of the multi-disciplinary experiment are to provide a high resolution pre- and post-stimulation characterization of fracture permeability and connectivity, to investigate patterns of preferential flow paths, to describe the pressure propagation during the stimulation phases and to evaluate the efficiency of the fracture-matrix heat exchanger. A comprehensive test & monitoring layout including a fair number of boreholes instrumented with a variety of sensors (e.g. pressure, strain, displacement, temperature, and seismic sensors) is designed to collect detailed data during multiple hydraulic stimulation runs. The diffusion of fluid pressure is expected to be governed mainly by the properties and geometry of the existent fracture network. The hydraulic transmissivity of fractures are in the range of 10-7 to 10-9 m2/s whereas the matrix rock has a very low hydraulic conductivity (K ˜ 10-12 m/s). As part of the stress measurement campaign during the pre-stimulation phase of the ISC experiment, a series of hydraulic fracturing (HF) and hydraulic tests in pre-existing fractures (HTPF) were conducted. The tests were accompanied by micro-seismic monitoring within several observation boreholes to investigate the initiation and propagation of the induced fractures. Together with results from over

  17. Clinical analysis of the rap stress stimulator applied for crus fracture after skeletal external fixation.

    Zhuang, Ping; Hong, Jiayuan; Chen, Wei; Wu, Jin; Ding, Zhenqi


    Open crus fracture is still difficult in clinical treatment because of the delayed fracture union and high rate of nonunion after the operation. A consensus has been reached that mechanical stress can promote fracture healing. We independently developed a stress stimulator, which can provide longitudinal pressure for the fixed fracture end of the lower legs to promote fracture healing. The purpose of this study is to explore the advantages and clinical effect of the rap stress stimulator applied for open crus fracture after skeletal external fixation. One hundred and sixty-five patients (183 limbs) who suffered from open tibia and fibula fracture received skeletal external fixation, of which 108 limbs were treated with the rap stress stimulator after external fixation and 75 limbs were treated with regular functional exercises of muscle contraction and joint activity only. Then the fracture healing time and rate of nonunion were compared between the two groups. The mean fracture healing time and rate of nonunion in the group treated with the rap stress stimulator were 138.27 ±4.45 days and 3.70% respectively, compared to 153.43 ±4.89 days and 10.67% in the group treated without the stimulator. The rap stress stimulator significantly shortened the fracture healing time and reduced the rate of nonunion for treating open tibia and fibula fractures.

  18. Incidence and Time to Return to Training for Stress Fractures during Military Basic Training

    Alexander M. Wood


    Full Text Available Currently, little is known about the length of time required to rehabilitate patients from stress fractures and their return to preinjury level of physical activity. Previous studies have looked at the return to sport in athletes, in a general population, where rehabilitation is not as controlled as within a captive military population. In this study, a longitudinal prospective epidemiological database was assessed to determine the incidence of stress fractures and the time taken to rehabilitate recruits to preinjury stage of training. Findings demonstrated a background prevalence of 5% stress fractures in Royal Marine training; femoral and tibial stress fractures take 21.1 weeks to return to training with metatarsal stress fractures being the most common injury taking 12.2 weeks. Rehabilitation from stress fractures accounts for 814 weeks of recruit rehabilitation time per annum. Stress fracture incidence is still common in military training; despite this stress fracture recovery times remain constant and represent a significant interruption in training. It takes on average 5 weeks after exercise specific training has restarted to reenter training at a preinjury level, regardless of which bone has a stress fracture. Further research into their prevention, treatment, and rehabilitation is required to help reduce these burdens.

  19. In-situ stress from hydraulic fracture measurements in G Tunnel, Nevada Test Site

    Smith, C.; Vollendorf, W. C.; Warren, W. E.


    Hydraulic fracture work in G Tunnel, Nevada Test Site, performed to obtain the in-situ stress state is discussed. Field equipment and procedures are described; analysis is developed to relate the hydraulic fracture pressures to the in-situ stress state. Pressure data are analyzed to provide estimates of the stress state at a number of locations in the tunnel complex. A unique feature of the work is the mineback - a mining process in which the rock is cut away to reveal the actual plane of the fracture. Advantages, limitations, and problem areas associated with extracting in-situ stress fields from hydraulic fracture pressure records are discussed in detail.

  20. The effect of fracture density and stress state on the static and dynamic bulk moduli of Westerly granite

    Blake, O. O.; Faulkner, D. R.


    Elastic properties are key parameters during the deformation of rocks. They can be measured statically or dynamically, but the two measurements are often different. In this study, the static and dynamic bulk moduli (Kstatic and Kdynamic) were measured at varying effective stress for dry and fluid-saturated Westerly granite with controlled fracture densities under isotropic and differential stress states. Isotropic fracturing of different densities was induced in samples by thermal treatment to 250, 450, 650, and 850°C. Results show that fluid saturation does not greatly affect static moduli but increases dynamic moduli. Under isotropic loading, high fracture density and/or low effective pressure results in a low Kstatic/Kdynamic ratio. For dry conditions Kstatic/Kdynamic approaches 1 at low fracture densities when the effective pressure is high, consistent with previous studies. Stress-induced anisotropy exists under differential stress state that greatly affects Kstatic compared to Kdynamic. As a result, the Kstatic/Kdynamic ratio is higher than that for the isotropic stress state and approaches 1 with increasing axial loading. The effect of stress-induced anisotropy increases with increasing fracture density. A key omission in previous studies comparing static and dynamic properties is that anisotropy has not been considered. The standard methods for measuring static elastic properties, such as Poisson's ratio, Young's and shear modulus, involve subjecting the sample to a differential stress state that promotes anisotropy. Our results show that stress-induced anisotropy resulting from differential stress state is a major contributor to the difference between static and dynamic elasticity and is dominant with high fracture density.

  1. Results of fracture mechanics tests on PNC SUS 304 plate

    Mills, W.J.; James, L.A.; Blackburn, L.D.


    PNC provided SUS 304 plate to be irradiated in FFTF at about 400/sup 0/C to a target fluence of 5 x 10/sup 21/ n/cm/sup 2/ (E > 0.1 MeV). The actual irradiation included two basically different exposure levels to assure that information would be available for the exposure of interest. After irradiation, tensile properties, fatigue-crack growth rates and J-integral fracture toughness response were determined. These same properties were also measured for the unirradiated material so radiation damage effects could be characterized. This report presents the results of this program. It is expected that these results would be applicable for detailed fracture analysis of reactor components. Recent advances in elastic-plastic fracture mechanics enable reasonably accurate predictions of failure conditions for flawed stainless steel components. Extensive research has focused on the development of J-integral-based engineering approach for assessing the load carrying capacity of low-strength, high-toughness structural materials. Furthermore, Kanninen, et al., have demonstrated that J-integral concepts can accurately predict the fracture response for full-scale cracked structures manufactured from Type 304 stainless steel.

  2. Numerical Simulation of Rock Fracturing under Laboratory True-Triaxial Stress Conditions

    Ghofrani Tabari, Mehdi; Hazzard, Jim; Young, R. Paul


    A True-triaxial test (TTT) also known as polyaxial test was carried out on saturated Fontainebleau sandstone to elevate our knowledge about the role of the intermediate principal stress on deformation, fracturing and failure patterns of the rock using acoustic emission (AE) monitoring. The induced AE activities were studied by location of the AE events and mapping them on the captured features in the post-mortem CT scan images of the failed sample. The time-lapse monitoring of the velocity structure and AE activity in the sample portrayed a deformational path which led to propagation of fractures and formation of failure patterns in the rock. Having these experimental results, we aimed at running a numerical model of our true-triaxial testing system using an Itasca software based on three-dimensional explicit finite-difference method called FLAC3D. The loads were applied at the end of each platen while the steel platens transferred the stress to the surface of the cubic specimen. In order to simulate the failure, randomly distributed strength demonstrated by Mohr-Columb failure criterion was implemented in the spatial elements of the model representing the random distribution of the micro-cracks. During the experiment, pseudo-boundary surfaces were formed along the minimum and intermediate principal stress axes in the rock due to non-uniform distribution of stress as a result of geometrical constraints including the corner effects and friction on the platen-rock surfaces. Both the real AE data as well as the numerical simulation verified that coalescence of micro-cracks mainly occurred around these pseudo-boundaries with highest stress gradients as well as highest velocity gradients in the rock specimen and formed curvi-planar fractures. The rock specimen strength and brittleness in the macro-scale was also obtained from the stress-strain curve which was consistent with the experimental laboratory measurements. Eventually, the failure of the rock specimen was


    Daniel R. Burns; M. Nafi Toksoz


    We have extended a three-dimensional finite difference elastic wave propagation model previously developed at the Massachusetts Institute of Technology (MIT) Earth Resources Laboratory (ERL) for modeling and analyzing the effect of fractures on seismic waves. The code has been translated into C language and parallelized [using message passing interface (MPI)] to allow for larger models to be run on Linux PC computer clusters. We have also obtained another 3-D code from Lawrence Berkeley Laboratory, which we will use for verification of our ERL code results and also to run discrete fracture models. Testing of both codes is underway. We are working on a new finite difference model of borehole wave propagation for stressed formations. This code includes coordinate stretching to provide stable, variable grid sizes that will allow us to model the thin fluid annulus layers in borehole problems, especially for acoustic logging while drilling (LWD) applications. We are also extending our analysis routines for the inversion of flexural wave dispersion measurements for in situ stress estimates. Initial results on synthetic and limited field data are promising for a method to invert cross dipole data for the rotation angle and stress state simultaneously. A meeting is being scheduled between MIT and Shell Oil Company scientists to look at data from a fractured carbonate reservoir that may be made available to the project. The Focus/Disco seismic processing system from Paradigm Geophysical has been installed at ERL for field data analysis and as a platform for new analysis modules. We have begun to evaluate the flow properties of discrete fracture distributions through a simple 2D numerical model. Initial results illustrate how fluid flow pathways are very sensitive to variations in the geometry and apertures of fracture network.

  4. Evaluation of Thompson's quadricepsplasty results in patients with knee stiffness resulted from femoral fracture

    Hamid Mousavi


    Full Text Available Background: Posttraumatic and/or postsurgical knee stiffness is one of the orthopedic complications which is difficult to be treated and can affect individual's life negatively. The aim of this study is to investigate the results of quadricepsplasty in patients with knee stiffness resulted from femoral fracture. Materials and Methods: This is a cross-sectional study on all patients with femoral fracture which has caused knee flexion limitation referred to Kashani and Al-Zahra Hospitals in Isfahan from January 2010 to March 2013. The type and site of fracture, joint extension, and fracture fixation technique were recorded. Moreover, the range of motion (ROM before surgery, under general anesthesia, and 3- and 6-month postoperation were measured. Results: Among the patients, 13 had a simple fracture (48% and 14 had a segmental fracture (51.9%. Considering the fracture site, 11, 10, and 6 patients had femoral (40.74%, supracondylar (37.3%, and femoral supracondylar (22.2% fractures, respectively. The fracture fixation was performed by the plate, external, and Wagner fixation techniques for 24 (88.9%, 2 (7.4%, and 1 (3.7% patients, respectively. The mean ROM before operation, under general anesthesia, and 3- and 6-month postoperation were determined to be 33.15° ± 24.73°, 122.60° ± 10.22°, 99.63° ± 16.52°, and 100.74° ± 15.67°, respectively. The mean ROM value at various stages was not similar (P < 0.001. The mean changes in the ROM were 79.2° ± 24.6° and 62.1° ± 19.7° in the cases with simple and segmental fractures, respectively. The mean changes in the knee ROM were significantly higher in simple fractures in comparison with the segmental femoral fracture (P = 0.03. Conclusion: We found Thompson's quadricepsplasty may successfully increase the range of knee flexion in knee fracture and also regardless of quadriceps time.

  5. Evaluation of Thompson's quadricepsplasty results in patients with knee stiffness resulted from femoral fracture.

    Mousavi, Hamid; Mir, Behrouz; Safaei, Ali


    Posttraumatic and/or postsurgical knee stiffness is one of the orthopedic complications which is difficult to be treated and can affect individual's life negatively. The aim of this study is to investigate the results of quadricepsplasty in patients with knee stiffness resulted from femoral fracture. This is a cross-sectional study on all patients with femoral fracture which has caused knee flexion limitation referred to Kashani and Al-Zahra Hospitals in Isfahan from January 2010 to March 2013. The type and site of fracture, joint extension, and fracture fixation technique were recorded. Moreover, the range of motion (ROM) before surgery, under general anesthesia, and 3- and 6-month postoperation were measured. Among the patients, 13 had a simple fracture (48%) and 14 had a segmental fracture (51.9%). Considering the fracture site, 11, 10, and 6 patients had femoral (40.74%), supracondylar (37.3%), and femoral supracondylar (22.2%) fractures, respectively. The fracture fixation was performed by the plate, external, and Wagner fixation techniques for 24 (88.9%), 2 (7.4%), and 1 (3.7%) patients, respectively. The mean ROM before operation, under general anesthesia, and 3- and 6-month postoperation were determined to be 33.15° ± 24.73°, 122.60° ± 10.22°, 99.63° ± 16.52°, and 100.74° ± 15.67°, respectively. The mean ROM value at various stages was not similar (P < 0.001). The mean changes in the ROM were 79.2° ± 24.6° and 62.1° ± 19.7° in the cases with simple and segmental fractures, respectively. The mean changes in the knee ROM were significantly higher in simple fractures in comparison with the segmental femoral fracture (P = 0.03). We found Thompson's quadricepsplasty may successfully increase the range of knee flexion in knee fracture and also regardless of quadriceps time.

  6. Stress analysis and optimization of Nd:YAG pulsed laser processing of notches for fracture splitting of a C70S6 connecting rod

    Kou, Shuqing; Gao, Yan; Zhao, Yong; Lin, Baojun [Jilin University, Changchun (China)


    The pulsed laser pre-processing of a notch as the fracture initiation source for the splitting process is the key mechanism of an advanced fracture splitting technology for C70S6 connecting rods. This study investigated the stress field of Nd:YAG pulsed laser grooving, which affects the rapid fracture initiation at the notch root and the controlled crack extension in the critical fracture splitting quality, to improve manufacturing quality. Thermal elastic-plastic incremental theory was applied to build the finite element analysis model of the stress field of pulsed laser grooving for fracture splitting based on the Rotary-Gauss body heat source. The corresponding numerical simulation of the stress field was conducted. The changes and distributions of the stress during pulsed laser grooving were examined, the influence rule of the primary technological parameters on the residual stress was analyzed, and the analysis results were validated by the corresponding cutting experiment. Results showed that the residual stress distribution was concentrated in the Heat-affected zone (HAZ) near the fracture splitting notch, which would cause micro-cracks in the HAZ. The stress state of the notch root in the fracture initiation direction was tensile stress, which was beneficial to the fracture initiation and the crack rapid extension in the subsequent fracture splitting process. However, the uneven distribution of the stress could lead to fracture splitting defects, and thus the residual stress should be lowered to a reasonable range. Decreasing the laser pulse power, increasing the processing speed, and lowering the pulse width can lower the residual stress. Along with the actual production, the reasonable main technological parameters were obtained.

  7. Presentation of metastatic carcinoma as pedal stress fracture and ingrown toenail.

    Mitchell, Dianne I; Riley, Philip J


    Metastatic lesions localized to the foot are rare. When present, such lesions are typically associated with a poor prognosis. A good history can help guide the clinician when formulating differential diagnoses for a questionable clinical presentation. We report the case of a patient presenting with findings indicative of a metatarsal stress fracture and an ingrown toenail, which eventually resulted in the diagnosis of metastatic disease from the lung. ACFAS Level of Clinical Evidence: 4.

  8. The Association of Femoral Neck Stress Fractures with Femoral Acetabular Impingement

    Safran, Marc R.; Goldin, Michael; Anderson, Christian; Fredericson, Michael; Stevens, Kathryn J.


    Objectives: To determine if there is an increased incidence of femoral acetabular impingement (FAI) in patients presenting with stress fractures of the femoral neck. Methods: After IRB approval, the imaging studies of 25 athletes (22 females, 3 males, mean age 26, range 19 - 39 years) with femoral neck stress injuries were assessed for the presence of features suggesting FAI, including acetabular retroversion, coxa profunda, abnormal femoral head-neck junction, fibrocystic change, os acetabulae, labral tear and chondral injury. All subjects had to have an adequate AP Pelvis radiograph, a lateral radiograph of the affected hip, and an MRI of the affected hip. The alpha angle, anterior offset ratio, and center to edge (CE) angle were measured on radiographs. The grade of stress injury was determined on MR images. All images and measurements were made by a musculoskeletal fellowship trained radiologist, a fellowship trained orthopaedic surgeon, an orthopaedic sports medicine fellow and a physical medicine and rehabilitation resident. Charts were reviewed to determine treatment of the stress fracture, outcome and final follow up, as well as to determine if the patient had any further treatment for their hip. Results: Of the 25 hips (18 right, 7 left) with femoral neck stress reactions, 9 were grade 2 (bone marrow edema), 5 were grade 3 (high T2 and low T1 marrow signal), and 11 were grade 4 (stress fracture). Twenty patients (80%) had coxa profunda - where the floor of the cotyloid fossa touches or extends beyond the ilioischial line (incidence in general population is 15.2% of males, and 19.4% of females). Coxa profunda, defined by the floor of the cotyloid fossa touching or extending beyond the ilioischial line and a center edge angle of more than 35o, was present in 28% of subjects. Acetabular retroversion as assessed by the crossover sign was present in 42% (normal incidence is 5% of population). Center edge angle was greater than 35o in 20% and greater than 40 o

  9. Sacral Stress Fracture Mimicking Lumbar Radiculopathy in a Mounted Police Officer: Case Report and Literature Review.

    Bednar, Drew A; Almansoori, Khaled


    Study Design Case report and review of the literature. Objective To present a unique case of L5 radiculopathy caused by a sacral stress fracture without neurologic compression. Methods We present our case and its clinical evolution and review the available literature on similar pathologies. Results Relief of the unusual mechanical loading causing sacral stress fracture led to rapid resolution of radiculopathy. Conclusion L5 radiculopathy can be caused by a sacral stress fracture and can be relieved by simple mechanical treatment of the fracture.

  10. Effects of laser heat treatment on the fracture morphologies of X80 pipeline steel welded joints by stress corrosion

    De-jun Kong; Cun-dong Ye


    The surfaces of X80 pipeline steel welded joints were processed with a CO2 laser, and the effects of laser heat treatment (LHT) on H2S stress corrosion in the National Association of Corrosion Engineers (NACE) solution were analyzed by a slow strain rate test. The frac-ture morphologies and chemical components of corrosive products before and after LHT were analyzed by scanning electron microscopy and energy-dispersive spectroscopy, respectively, and the mechanism of LHT on stress corrosion cracking was discussed. Results showed that the fracture for welded joints was brittle in its original state, while it was transformed to a ductile fracture after LHT. The tendencies of hydro-gen-induced corrosion were reduced, and the stress corrosion sensitivity index decreased from 35.2%to 25.3%, indicating that the stress corrosion resistance of X80 pipeline steel welded joints has been improved by LHT.

  11. Tensile and fracture toughness test results of neutron irradiated beryllium

    Chaouadi, R.; Moons, F.; Puzzolante, J.L. [Centre d`Etude de l`Energie Nucleaire, Mol (Belgium)


    Tensile and fracture toughness test results of four Beryllium grades are reported here. The flow and fracture properties are investigated by using small size tensile and round compact tension specimens. Irradiation was performed at the BR2 material testing reactor which allows various temperature and irradiation conditions. The fast neutron fluence (>1 MeV) ranges between 0.65 and 2.45 10{sup 21} n/cm{sup 2}. In the meantime, un-irradiated specimens were aged at the irradiation temperatures to separate if any the effect of temperature from irradiation damage. Test results are analyzed and discussed, in particular in terms of the effects of material grade, test temperature, thermal ageing and neutron irradiation. (author)


    Hiroyuki Fujioka


    Full Text Available A 17-year-old boy, who played a weight lifting in high school, sustained stress fracture of the first rib without any causes. We successfully treated first rib stress fracture with limitation of using the upper extremity and with using low-intensity pulsed ultrasound

  13. A Comparison between Deep and Shallow Stress Fields in Korea Using Earthquake Focal Mechanism Inversions and Hydraulic Fracturing Stress Measurements

    Lee, Rayeon; Chang, Chandong; Hong, Tae-kyung; Lee, Junhyung; Bae, Seong-Ho; Park, Eui-Seob; Park, Chan


    We are characterizing stress fields in Korea using two types of stress data: earthquake focal mechanism inversions (FMF) and hydraulic fracturing stress measurements (HF). The earthquake focal mechanism inversion data represent stress conditions at 2-20 km depths, whereas the hydraulic fracturing stress measurements, mostly conducted for geotechnical purposes, have been carried out at depths shallower than 1 km. We classified individual stress data based on the World Stress Map quality ranking scheme. A total of 20 FMF data were classified into A-B quality, possibly representing tectonic stress fields. A total of 83 HF data out of compiled 226 data were classified into B-C quality, which we use for shallow stress field characterization. The tectonic stress, revealed from the FMF data, is characterized by a remarkable consistency in its maximum stress (σ1) directions in and around Korea (N79±2° E), indicating a quite uniform deep stress field throughout. On the other hand, the shallow stress field, represented by HF data, exhibits local variations in σ1 directions, possibly due to effects of topography and geologic structures such as faults. Nonetheless, there is a general similarity in σ1 directions between deep and shallow stress fields. To investigate the shallow stress field statistically, we follow 'the mean orientation and wavelength analysis' suggested by Reiter et al. (2014). After the stress pattern analysis, the resulting stress points distribute sporadically over the country, not covering the entire region evenly. In the western part of Korea, the shallow σ1directions are generally uniform with their search radius reaching 100 km, where the average stress direction agrees well with those of the deep tectonic stress. We note two noticeable differences between shallow and deep stresses in the eastern part of Korea. First, the shallow σ1 orientations are markedly non-uniform in the southeastern part of Korea with their search radius less than 25 km

  14. Stress corrosion-controlled rates of mode I fracture propagation in calcareous bedrock

    Voigtlaender, Anne; Leith, Kerry; Krautblatter, Michael


    Surface bedrock on natural rock slopes is subject to constant and cyclic environmental stresses (wind, water, wave, ice, seismic or gravitational). Studies indicate that these stresses range up to several hundred kPa, generally too low to cause macroscopic changes in intact rock, although clear evidence of fracture generation, crack propagation and weathering of bedrock illustrates the effect of environmental stresses at the Earth's surface. We suggest that material degradation and its extent, is likely to be controlled by the rate of stress corrosion cracking (SCC). Stress corrosion is a fluid-material reaction, where fluids preferentially react with strained atomic bonds at the tip of developing fractures. Stress corrosion in ferrous and siliceous materials is often accepted as the fracture propagation and degradation rate-controlling process where materials are subject to stresses and fluids. Although evidence for chemical weathering in propagating bedrock fractures is clear in natural environments, the physical system and quantification of stress corrosion in natural rocks is yet to be addressed. Here, we present preliminary data on the relationship between stresses at levels commonly present on natural rock slopes, and material damage resulting from stress corrosion under constant or cyclic tensile loading. We undertake single notch three-point bending tests (SNBT) on fresh calcareous bedrock specimens (1100x100x100mm) over a two-month period. Two beams containing an artificial notch are stressed to 75% of their ultimate strength, and a constant supply of weak acid is applied at the notch tip to enhance chemical reactions. A third, unloaded, beam is also exposed to weak acid in order to elucidate the contribution of stress corrosion cracking to the material degradation. Stresses at the tip of propagating cracks affect the kinetics of the chemical reaction in the specimen exposed to both loading and corrosion, leading to an increase in degradation, and greater

  15. Acute Stress Fracture of the Pelvis after Total Hip Arthroplasty: A Case Report.

    Akinbo, Oluwaseun; Tyagi, Vineet


    Acute hip pain following total hip arthroplasty (THA) could have numerous causes to include stress fracture of the pelvis. Stress fractures of the pelvis are rare and have been reported to involve the medial wall and the pubic ramus. A unique case is presented demonstrating the clinical presentation and management of an acute stress fracture of ilium and anterior column following a THA. A 72-year-old man underwent an uncomplicated right THA. He was noted to have femoral head resorption and thin osteoporotic bone intraoperatively. He initially did well postoperatively and ambulating without pain or assistive devices. Within 1 month of surgery, he returned with acute right hip pain without any traumatic event. Radiographs showed migration of the acetabular component and computed tomography scan confirmed a fracture through the ilium. The patient underwent revision surgery, where the fracture was reduced and internal fixation was achieved with a reconstruction plate and acetabular cage construct. At 9 months postoperatively, the patient remained pain-free with full weight bearing and with stable radiographs. Elderly patients who undergo THA may have low bone mineral density. These patients can develop stress fractures in their pelvis after surgery. These fractures may involve the medial wall, posterior column, or posterior wall. In patients who develop atraumatic pain postoperatively, it is important to consider for potential stress fractures of the ilium and evaluate appropriately with imaging. In these cases, revision surgery can be necessary to provide fixation of the stress fracture.

  16. Exercise-induced rib stress fractures: influence of reduced bone mineral density

    Vinther, Anders; Kanstrup, Inge-Lis; Christiansen, Erik;


    Exercise-induced rib stress fractures have been reported frequently in elite rowers during the past decade. The etiology of rib stress fractures is unclear, but low bone mineral density (BMD) has been suggested to be a potential risk factor for stress fractures in weight-bearing bones. The present...... study investigated BMD in seven Danish national team rowers with previous rib stress fracture (RSF) and 7 controls (C) matched for gender, age, height, weight and training experience. Total body scan and specific scans of the lumbar spine (L2-L4), femoral neck and distal radius were performed using...... density may be a potential risk factor for the development of exercise-induced rib stress fractures in elite rowers....

  17. The area moment of inertia of the tibia: a risk factor for stress fractures.

    Milgrom, C; Giladi, M; Simkin, A; Rand, N; Kedem, R; Kashtan, H; Stein, M; Gomori, M


    In a prospective study of stress fractures among Israeli infantry recruits, the area moment of inertia of the tibia was found to have a statistically significant correlation with the incidence of tibial, femoral and total stress fractures. Recruits with "low" area moments of inertia of the tibia were found to have higher stress fracture morbidity than those with "high" area moments of inertia. The best correlation was obtained when the area moment of inertia was calculated about the AP axis of bending at a cross-sectional level corresponding to the narrowest tibial width on lateral X-rays, a point which is at the distal quarter of the tibia. This finding indicates that bending forces about the approximate AP axis are an important causal factor for tibial and many other stress fractures. The bone's bending strength, or ability to resist bending moments, as measured by the area moment of inertia, helps determine risk to stress fracture.

  18. Stress fractures of the base of the metatarsal bones in young trainee ballet dancers.

    Albisetti, Walter; Perugia, Dario; De Bartolomeo, Omar; Tagliabue, Lorenzo; Camerucci, Emanuela; Calori, Giorgio Maria


    Classical ballet is an art form requiring extraordinary physical activity, characterised by rigorous training. These can lead to many overuse injuries arising from repetitive minor trauma. The purpose of this paper is to report our experience in the diagnosis and treatment of stress fractures at the base of the second and third metatarsal bones in young ballet dancers. We considered 150 trainee ballet dancers from the Ballet Schools of "Teatro Alla Scala" of Milan from 2005 to 2007. Nineteen of them presented with stress fractures of the base of the metatarsal bones. We treated 18 dancers with external shockwave therapy (ESWT) and one with pulsed electromagnetic fields (EMF) and low-intensity ultrasound (US); all patients were recommended rest. In all cases good results were obtained. The best approach to metatarsal stress fractures is to diagnose them early through clinical examination and then through X-ray and MRI. ESWT gave good results, with a relatively short time of rest from the patients' activities and a return to dancing without pain.

  19. Diagnosis, treatment, and rehabilitation of stress fractures in the lower extremity in runners

    Kahanov L


    Full Text Available Leamor Kahanov,1 Lindsey E Eberman,2 Kenneth E Games,2 Mitch Wasik2 1College of Health Science, Misericordia University, Dallas, PA, USA; 2Department of Applied Medicine and Rehabilitation, Indiana State University, Terre Haute, IN, USA Abstract: Stress fractures account for between 1% and 20% of athletic injuries, with 80% of stress fractures in the lower extremity. Stress fractures of the lower extremity are common injuries among individuals who participate in endurance, high load-bearing activities such as running, military and aerobic exercise and therefore require practitioner expertise in diagnosis and management. Accurate diagnosis for stress fractures is dependent on the anatomical area. Anatomical regions such as the pelvis, sacrum, and metatarsals offer challenges due to difficulty differentiating pathologies with common symptoms. Special tests and treatment regimes, however, are similar among most stress fractures with resolution between 4 weeks to a year. The most difficult aspect of stress fracture treatment entails mitigating internal and external risk factors. Practitioners should address ongoing risk factors to minimize recurrence. Keywords: medial tibial stress syndrome, stress injury, nonunion stress fracture

  20. Subtrochanteric fractures in bisphosphonate-naive patients: results from the HORIZON-recurrent fracture trial.

    Adachi, Jonathan D; Lyles, Kenneth; Boonen, Steven; Colón-Emeric, Cathleen; Hyldstrup, Lars; Nordsletten, Lars; Pieper, Carl; Recknor, Chris; Su, Guoqin; Bucci-Rechtweg, Christina; Magaziner, Jay


    Our purpose was to characterize the risks of osteoporosis-related subtrochanteric fractures in bisphosphonate-naive individuals. Baseline characteristics of patients enrolled in the HORIZON-Recurrent Fracture Trial with a study-qualifying hip fracture were examined, comparing those who sustained incident subtrochanteric fractures with those sustaining other hip fractures. Subjects were bisphosphonate-naive or had a bisphosphonate washout period of 6-24 months and subsequently received an annual infusion of zoledronic acid 5 mg or placebo after low-trauma hip-fracture repair. In total, 2,127 men and women were included. Of the qualifying hip fractures, 5.2% were subtrochanteric, 54.8% femoral neck, 33.0% intertrochanteric, and 7.1% other (generally complex fractures of mixed type). Significant baseline (pre-hip fracture) differences were seen between index hip-fracture types, with the percentage of patients with extreme mobility problems being twofold higher in patients with index subtrochanteric fracture (9.9%) compared to other patients. The distribution of hip-fracture types was similar between the treatment groups at baseline. No patients with index subtrochanteric fractures and six patients with other qualifying hip fractures reported prior bisphosphonate use. Only one further subtrochanteric fracture occurred in each treatment group over an average 2-year patient follow-up. Subtrochanteric fractures are not uncommon in bisphosphonate-naive patients. Extreme difficulties with mobility may be a unique risk factor predisposing to development of incident subtrochanteric fractures rather than other types of hip fracture. In patients with recent hip fracture who received zoledronic acid therapy, the incidence of new subtrochanteric fractures was too small to draw any meaningful conclusions.

  1. Subtrochanteric Fractures in Bisphosphonate-Naive Patients: Results from the HORIZON-Recurrent Fracture Trial


    Our purpose was to characterize the risks of osteoporosis-related subtrochanteric fractures in bisphosphonate-naive individuals. Baseline characteristics of patients enrolled in the HORIZON-Recurrent Fracture Trial with a study-qualifying hip fracture were examined, comparing those who sustained incident subtrochanteric fractures with those sustaining other hip fractures. Subjects were bisphosphonate-naive or had a bisphosphonate washout period of 6–24 months and subsequently received an annu...

  2. The effects of residual stress, viscoelastic and thermodynamic parameters on apparent fracture toughness of dental bilayer ceramic composites

    Taskonak, Burak

    Bilayer dental ceramic composites used for fixed partial dentures are becoming more widely used in dental practices because of their biocompatibility, aesthetic properties, and chemical durability. However, large statistical variations in the strength of ceramics are associated with the structural flaws as a result of processing and complex stress states within the surfaces of the materials because of thermal properties of each layer. In addition, partial delaminations of the veneer layer and connector fractures of bilayer ceramic fixed partial dentures (FPDs) have been observed in a clinical study which is a part of this dissertation. Analysis of fracture surfaces of failed FPDs reveals that such fractures of the veneering ceramic are most likely caused by lateral crack growth. Global residual stresses associated with the coefficient of thermal expansion differences between core and veneering ceramics can cause lateral crack initiation. Also, rapid cooling of bilayer ceramics from the sintering temperature of the glass veneer may not allow the interfacial stresses in the viscoelastic glass to relax to equilibrium values. This can further contribute to the propagation of lateral cracks. Furthermore, local residual stresses that develop in the plastic deformation zone below sharp contact areas on the occlusal surface are another contributor to lateral crack growth. Superposition of global residual stresses and a Boussinesq stress field can incrementally increase the possibility of lateral crack growth. The long-range goals of this study are to critically analyze the lateral crack growth mechanisms associated with residual stresses, to modify residual tensile stress distributions by controlled heat treatment, and to minimize the probability of veneering ceramic fractures. Four approaches were used to accomplish these goals: (1) clinical evaluation of a bilayer ceramic fixed partial denture system; (2) fracture surface analysis of clinically failed FPDs; (3

  3. Experimental study on time-dependent stress and strain of in-plane shear(ModeⅡ) fracture process of rock

    王志; 饶秋华; 谢海峰


    Shear-box test with strain measurement was used to study time-dependent stress and strain of in-plane shear(Mode Ⅱ) fracture process of rock and to reveal the mechanism of Mode Ⅱ fracture.Numerical results show that the maximum shear stress τmax at the crack tip is much larger than the maximum tensile stress σ1 and the ratio of τmax/σ1 is about 5,which favors Mode Ⅱ fracture of rock.Test results indicate that the strain-time curve comprises three stages:the linear deformation stage,the micro-cracking stage and the macroscopic crack propagation.The strain in the direction of the original notch plane is negative,due to restraining effect of compressive loading applied to the original notch plane.Both σ1 and τmax are increased as the load increases,but the slope of τmax is larger than that of σ1 and the value of τmax is always larger than that of σ1.Therefore,τmax reaches its limited value at peak load before σ1 and results in Mode Ⅱ fracture of rock.Shear-box(i.e.compression-shear) test becomes a potential standard method for achieving the true Mode Ⅱ fracture and determining Mode Ⅱ fracture toughness of rock.

  4. Evolution of stress and seismicity in fractured geothermal reservoirs

    Schoenball, Martin


    Heat Mining, Soultz, forms the basis of the studies. The PhD project was conducted partly within the FP7 GEISER (Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs) project, funded by the European Commission and it benefited largely from fruitful collaborations with Universite de Strasbourg, Geowatt AG, Zuerich, GFZ German Research Centre for Geosciences, Potsdam and CSIRO Earth Science and Resources Engineering, Perth. In the first study, I analyze whether interaction of seismicity by static stress transfer plays a significant role on the spatio-temporal evolution of seismicity. I follow an analytical approach to compute the displacement field of a rectangular earthquake source. Through stacking of several sources, realistic slip distributions are obtained. The analysis reveals seemingly random distributed patches of stress increase and stress decrease of less than ± 1 MPa, except for very localized areas. Since the fracture planes have varying orientations, they form a volumetric fracture network. About 60% of hypocenters are found in areas with increased Coulomb stress where their potential for failure was increased by static stress transfer. A different behavior is observed for slippage of neighboring asperities on larger fault zones. Here, failure of asperities leads to a direct stress increase in adjacent asperities, which are then more likely to fail. This is exemplified on a cluster of events occurring on the largest fault zone in Soultz, after shut-in of the well GPK2. Subsequently, the peculiar behavior of seismicity and the hydraulic regime following shut-in of the well GPK2 is highlighted and investigated by further analysis of focal mechanism solutions. An increase of the thrust faulting component following shut-in is observed. The changes of the stress field are derived from spatio-temporally resolved inversions of focal mechanism solutions. A very strong reduction of the maximum horizontal stress and an increase of the

  5. Measuring Stress-dependent Fluid Flow Behavior in Fractured Porous Media

    Huo, Da; Benson, Sally


    Maintaining long-term storage of CO2 is one of the most important factors for selecting the site for a geological CO2 storage project. Nevertheless, it is important to be prepared for possible leakage due to leaking wells or leakage pathways through the seal of a storage reservoir. This research project is motivated by the need to understand unexpected CO2 leakage. The goal of this research is to investigate stress-dependent fracture permeability and relative permeability of CO2/brine systems. Laboratory measurements of fracture permeability and fracture apertures have been made as a function of effective stress. The phenomenon that permeability decreases with effective pressure increase is observed. Due to deformation of the fracture surface during periods with high effective stress, hysteretic behavior of fractured rock permeability is also observed in core flood experiments. A series of experiments are conducted to investigate permeability hysteresis. A single saw-cut fracture is created in the rock sample to simplify the problem and to focus on the fracture itself. Permeability is measured using a high pressure core flood apparatus with X-Ray CT scanning to measure the fracture aperture distributions. Two permeability data sets, including a high permeability fractured Berea Sandstone and a low permeability fractured Israeli Zenifim Formation sandstone, show clear hysteretic behavior in both permeability and fracture aperture in repeated cycles of compression and decompression. Due to closure of the fracture aperture, when a fractured rock is compressed axially, the permeability has an exponential decline with effective pressure, as expected from stress-dependent permeability theory. When the fractured rock is decompressed afterwards, permeability increases, but not along the compression pathway and never returns to the original value. Depending on the nature of the fracture and host rock, permeability can decrease from a factor of 2 to 40. After one or more

  6. Review of possible correlations between in situ stress and PFL fracture transmissivity data at Forsmark

    Martin, Derek (University of Alberta (United States)); Follin, Sven (SF GeoLogic AB (Sweden))


    In laboratory samples, the fracture transmissivity decreases significantly as the confining stress increases. While these experimental relationships are widely accepted and validated on laboratory samples, it is unknown if such relationships exist in situ or if these relationships can be scaled from the centimetre-scale laboratory tests to the metre-scale of in situ fractures. The purpose of this work is to assess the relationship between the structural-hydraulic data gathered in deep, cored boreholes at Forsmark and the in situ stress state acting on the these fractures. In conclusion, there does not appear to be sufficient evidence from these analyses to support the notion that the magnitude of the flow along the fractures at Forsmark is solely controlled by the in situ stress acting on the fracture. This should not be surprising because the majority of the fractures formed more than 1 billion years ago and the current in situ stress state has only been active for the past 12 million years. It is more likely that the transmissivity values are controlled by fracture roughness, open channels within the fracture, fracture stiffness and fracture infilling material

  7. Serum 25-Hydroxyvitamin D Levels and Stress Fractures in Military Personnel: A Systematic Review and Meta-analysis.

    Dao, Dyda; Sodhi, Sukhmani; Tabasinejad, Rasam; Peterson, Devin; Ayeni, Olufemi R; Bhandari, Mohit; Farrokhyar, Forough


    Low serum 25-hydroxyvitamin D (25(OH)D) levels have been associated with stress fractures in various physically active populations such as the military. To examine the association between serum 25(OH)D levels and stress fractures in the military. Systematic review and meta-analysis. Relevant studies were identified through searching multiple databases and manually screening reference lists. Two reviewers independently selected the included studies by applying the eligibility criteria to the title, abstract, and/or full text of the articles yielded in the search. Two reviewers also independently conducted the methodological quality assessment and data extraction. A random-effects model was used to calculate the mean difference (MD) with 95% CI in serum 25(OH)D levels between stress fracture cases and controls. Nine observational studies on lower extremity stress fractures were eligible, and 1 was excluded due to inadequate data. A total of 2634 military personnel (age, 18-30 years; 44% male) with 761 cases (16% male) and 1873 controls (61% male) from 8 studies were included in the analysis. Three of the 8 studies measured serum 25(OH)D levels at the time of stress fracture diagnosis, and the 5 remaining studies measured serum 25(OH)D levels at the time of entry into basic training. The mean serum 25(OH)D level was lower in stress fracture cases than in controls at the time of entry into basic training (MD, -2.63 ng/mL; 95% CI, -5.80 to 0.54; P = .10; I(2) = 65%) and at the time of stress fracture diagnosis (MD, -2.26 ng/mL; 95% CI, -3.89 to -0.63; P = .007; I(2) = 42%). Despite the inherent limitations of the included studies, the study results suggest some association between low serum 25(OH)D levels and lower extremity stress fractures in military personnel. Given the rigorous training of military personnel, implementing strategies to ensure sufficient 25(OH)D levels may be beneficial for reducing the risk of stress fractures. © 2014 The Author(s).

  8. Toe and Metatarsal Fractures (Broken Toes)

    ... rest is the only treatment needed to promote healing of a stress or traumatic fracture of a metatarsal bone. Avoid the offending activity. Because stress fractures result from repetitive stress, it ...

  9. Dry fracture method for simultaneous measurement of in-situ stress state and material properties

    Serata, S. [Serata Geomechanics, Inc., Richmond, CA (United States); Oka, S.; Kikuchi, S. [JDC Corp., Tokyo (Japan)


    Based on the dry fracture principle, a computerized borehole probe has been developed to measure stress state and material properties, simultaneously. The probe is designed to obtain a series of measurements in a continuing sequence along a borehole length, without any interruptive measures, such as resetting packers, taking indentation of borehole wall, overcoming, etc. The new dry fracture probe for the single fracture method is designed to overcome the difficulties posed by its ancestor which was based on the double fracture method. The accuracy of the single fracture method is confirmed by a close agreement with the theory, FE modeling and laboratory testing.

  10. Radiological findings and healing patterns of incomplete stress fractures of the pars interarticularis

    Dunn, Andrew J.; Campbell, Robert S.D. [Royal Liverpool and Broadgreen University Teaching Hospitals, Department of Medical Imaging, Liverpool (United Kingdom); Mayor, Peter E. [Leighton Hospital, Department of Medical Imaging, Crewe, Cheshire (United Kingdom); Rees, Dai [Robert Jones and Agnes-Hunt Orthopaedic Hospital, Department of Orthopaedic Surgery, Oswestry, Shropshire (United Kingdom)


    The objective was to retrospectively record the CT and MRI features and healing patterns of acute, incomplete stress fractures of the pars interarticularis. The CT scans of 156 adolescents referred with suspected pars interarticularis stress fractures were reviewed. Patients with incomplete (grade 2) pars fractures were included in the study. Fractures were assessed on CT according to vertebral level, location of cortical involvement and direction of fracture propagation. MRI was also performed in 72 of the 156 cases. MRI images of incomplete fractures were assessed for the presence of marrow oedema and cortical integrity. Fracture healing patterns were characterised on follow-up CT imaging. Twenty-five incomplete fractures were identified in 23 patients on CT. All fractures involved the inferior or infero-medial cortex of the pars and propagated superiorly or superolaterally. Ninety-two percent of incomplete fractures demonstrated either complete or partial healing on follow-up imaging. Two (8%) cases progressed to complete fractures. Thirteen incomplete fractures in 11 patients confirmed on CT also had MRI, and 92% demonstrated oedema in the pars. Ten out of thirteen fractures (77%) showed a break in the infero-medial cortex with intact supero-lateral cortex, which correlated with the CT findings. MRI incorrectly graded one case as a complete (grade 3) fracture, and 2 cases as (grade 1) stress reaction. Six fractures had follow-up MRI, 67% showed partial or complete cortical healing, and the same number showed persistent marrow oedema. Incomplete fracture of the pars interarticularis represents a stage of the evolution of a complete stress fracture. The direction of fracture propagation is consistent, and complete healing can be achieved in most cases with appropriate clinical management. CT best demonstrates fracture size and extent, and is the most appropriate modality for follow-up. MRI is limited in its ability to fully depict the cortical integrity of

  11. Atypical bisphosphonate-associated subtrochanteric and femoral shaft stress fractures: diagnostic features on bone scan.

    Probst, Stephan; Rakheja, Rajan; Stern, Jerry


    A 69-year-old woman presented with a spontaneous right subtrochanteric hip fracture. Pan-imaging following orthopedic repair failed to identify a primary malignancy to explain the presumed pathologic basis for this fracture. The patient then underwent bone scintigraphy and SPECT/CT which showed mild uptake in multifocal endosteal thickening of the lateral left femoral diaphysis, diagnostic of bisphosphonate-associated femoral shaft stress fractures, but no evidence of metastatic bone disease. Atypical bisphosphonate-associated subtrochanteric and femoral shaft stress fractures have a fairly specific appearance on bone scintigraphy, and nuclear medicine physicians should be aware of this relatively infrequent emerging pathology.

  12. Development of joints and shear fractures in the Kuqa depression and its implication to regional stress field switching

    ZHANG; Zhongpei; WANG; Qingchen


    The superimposed basin must have undergone the changes of regional stress field. Study on the nature and switch of regional stress field of superimposed basin is very useful to understanding its stress state and tectonic events during its formation and evolution. As sensitive markers of small stress changes, joint and shear fracture, characterized by consistency of orientation over wide area, can be used to reconstruct paleostress state and its evolution. Detailed observations and analysis on the orientations, geometrical patterns, sequences of joints and shear fractures and their chronological relation to faults and folds show that, the NEE-SWW systematic joints and NNW-SSE systematic joints developed in the Mesozoic and Cenozoic strata are much more prominent than NW-SE systematic joints and shear fractures with different orientations. And the NWW-SEE and NW-SE systematic joints formed later than NEE-SWW systematic joints but earlier than shear fractures with different orientations. According to the relationships between joint and shear fractures and stress, the NEE-SWW systematic joints are inferred to result from lateral weak extension caused by the late Cretaceous regional uplift, while the NNW-SSE and NW-SE systematic joints are interpreted as syn-tectonic deformation relating to strong N-S compression in the Neogene. But some conjugate shear fractures occur probably due to sinistral strike-slip faulting in the Kuqa depression. At the beginning of the Neogene, the stress field changed and the maximal principal stress σ1 switched from vertical to horizontal.

  13. Tectonic Stress Wave,Micro-fracture Wave,and a Modified Elastic-Rebound Model of Earthquakes

    Zhao Fuyuan


    Based on a sample of some real earthquakes,we have suggested in previous papers that there is a density-tectonic stress wave with ultra-low frequency which is emitted from the epicenter region for months before earthquakes,and a micro-fracture wave 1~10 days before earthquakes.The former has been observed by different kinds of measurements and the latter has been observed by a few chance observations which consists of electromagnetic,gravitational and sonic fluctuations.We show real observational results that depict the two waves and they have very different frequencies,which are not difficult to discriminate.The classicaI elastic-rebound model is one of the most influential theories on earthquakes,and the thermodynamic elastic-rebound model has amended the classical framework.Considering the two waves above,we attempt to further modify the elasticrebound model,and the new framework could be called the"micro-fracture elasticrebound model".We infer that tectonic earthquakes could have three special phases:the accumulation of tectonic stress,micro-fracture,and main-fracture.Accordingly,there would be three waves which come from the epicenter of a tectonic earthquake,i.e.,the tectonic stress wave with ultra-low frequency a few months before the earthquake,the micro-fracture wave about 1~10 days before the earthquake and the main-fracture wave(common earthquake wave).

  14. San Juan Fracture Characterization Project: Status and current results

    Majer, E.L.; Daley, T.M.; Myer, L.R.; Nihei, K.; Queen, J.; Sinton, J.; Murphy, J.; Fortuna, M.; Lynn, H.B.; Imhoff, M.A.; Wilson, R.


    The overall objectives of this report are to extend current state-of-the-art 3-D imaging to extract the optimal information for fracture quantification and to develop next generation capability in fracture imaging for true 3-D imaging of the static and dynamic fracture properties.


    D. Nitin Reddy


    Full Text Available BACKGROUND Among the femoral shaft injuries, upper femoral fractures present a peculiar problem of securing effective neutralization of deforming forces. The mechanical stresses at this level are very high, as they occur at the junction between the trabecular and cortical zone and also because of the deforming forces due to peculiar muscle insertion to the proximal and distal fragments. The present study was conducted to assess the utility and effectiveness of Proximal Femoral Nail evolved by AO-ASIF in 1997, for various types of upper femoral fractures. MATERIAL AND METHOD The present study consists of the patients admitted to Orthopaedic Units of KIMS Hospital, between June 2012 and July 2014; 1267 fracture cases were treated in Department of Orthopaedics, Konaseema Institute of Medical Sciences, Amalapuram, during this period. Of these 264 patients were admitted for femoral fractures. Of the 264 femoral fractures, 18 patients above the age of 20 years with subtrochanteric fractures were included in this study. RESULT Reduction was good in 72.2% (13 of the cases. Acceptable reduction was achieved in 3 (16.6% patients. Poor reduction was noted in 2 (11.1% patients. One of them were of elderly age group and had poor outcome at final follow-up. SUMMARY AND CONCLUSION From this sample study, we conclude that Proximal Femoral Nail is a good implant for the treatment of subtrochanteric fractures of femur provided optimal reduction of the fracture and good positioning of the nail and screws are achieved.

  16. Pace bowlers in cricket with history of lumbar stress fracture have increased risk of lower limb muscle strains, particularly calf strains

    John Orchard


    Full Text Available John Orchard1, Patrick Farhart2, Alex Kountouris3, Trefor James3, Marc Portus31School of Public Health, University of Sydney, Australia; 2Punjab Kings XI team, Indian Premier League, India; 3Cricket Australia, Melbourne, AustraliaObjective: To assess whether a history of lumbar stress fracture in pace bowlers in cricket is a risk factor for lower limb muscle strains.Methods: This was a prospective cohort risk factor study, conducted using injury data from contracted first class pace bowlers in Australia during seasons 1998–1999 to 2008–2009 inclusive. There were 205 pace bowlers, 33 of whom suffered a lumbar stress fracture when playing first class cricket. Risk ratios ([RR] with 95% confidence intervals[CI] were calculated to compare the seasonal incidence of various injuries between bowlers with a prior history of lumbar stress fracture and those with no history of lumbar stress fracture.Results: Risk of calf strain was strongly associated with prior lumbar stress fracture injury history (RR = 4.1; 95% CI: 2.4–7.1. Risks of both hamstring strain (RR = 1.5; 95% CI: 1.03–2.1 and quadriceps strain (RR = 2.0; 95% CI: 1.1–3.5 were somewhat associated with history of lumbar stress fracture. Risk of groin strain was not associated with history of lumbar stress fracture (RR = 0.7; 95% CI: 0.4–1.1. Other injuries showed little association with prior lumbar stress fracture, although knee cartilage injuries were more likely in the non-stress fracture group.Conclusion: Bony hypertrophy associated with lumbar stress fracture healing may lead to subsequent lumbar nerve root impingement, making lower limb muscle strains more likely to occur. Confounders may be responsible for some of the findings. In particular, bowling speed is likely to be independently correlated with risk of lumbar stress fracture and risk of muscle strain. However, as the relationship between lumbar stress fracture history and calf strain was very strong, and that there is a

  17. Residual stress and damage-induced critical fracture on CO2 laser treated fused silica

    Matthews, M; Stolken, J; Vignes, R; Norton, M


    Localized damage repair and polishing of silica-based optics using mid- and far-IR CO{sub 2} lasers has been shown to be an effective method for increasing optical damage threshold in the UV. However, it is known that CO{sub 2} laser heating of silicate surfaces can lead to a level of residual stress capable of causing critical fracture either during or after laser treatment. Sufficient control of the surface temperature as a function of time and position is therefore required to limit this residual stress to an acceptable level to avoid critical fracture. In this work they present the results of 351 nm, 3 ns Gaussian damage growth experiments within regions of varying residual stress caused by prior CO{sub 2} laser exposures. Thermally stressed regions were non-destructively characterized using polarimetry and confocal Raman microscopy to measure the stress induced birefringence and fictive temperature respectively. For 1 {approx} 40s square pulse CO{sub 2} laser exposures created over 0.5-1.25 kW/cm{sup 2} with a 1-3 mm 1/e{sup 2} diameter beam (T{sub max} {approx} 1500-3000 K), the critical damage site size leading to fracture increases weakly with peak temperature, but shows a stronger dependence on cooling rate, as predicted by finite element hydrodynamics simulations. Confocal micro-Raman was used to probe structural changes to the glass over different thermal histories and indicated a maximum fictive temperature of 1900K for T{sub max} {ge} 2000 K. The effect of cooling rate on fictive temperature caused by CO{sub 2} laser heating are consistent with finite element calculations based on a Tool-Narayanaswamy relaxation model.


    Walter, Matthew [Structural Integrity Associates, Inc.; Yin, Shengjun [ORNL; Stevens, Gary [U.S. Nuclear Regulatory Commission; Sommerville, Daniel [Structural Integrity Associates, Inc.; Palm, Nathan [Westinghouse Electric Company, Cranberry Township, PA; Heinecke, Carol [Westinghouse Electric Company, Cranberry Township, PA


    In past years, the authors have undertaken various studies of nozzles in both boiling water reactors (BWRs) and pressurized water reactors (PWRs) located in the reactor pressure vessel (RPV) adjacent to the core beltline region. Those studies described stress and fracture mechanics analyses performed to assess various RPV nozzle geometries, which were selected based on their proximity to the core beltline region, i.e., those nozzle configurations that are located close enough to the core region such that they may receive sufficient fluence prior to end-of-life (EOL) to require evaluation of embrittlement as part of the RPV analyses associated with pressure-temperature (P-T) limits. In this paper, additional stress and fracture analyses are summarized that were performed for additional PWR nozzles with the following objectives: To expand the population of PWR nozzle configurations evaluated, which was limited in the previous work to just two nozzles (one inlet and one outlet nozzle). To model and understand differences in stress results obtained for an internal pressure load case using a two-dimensional (2-D) axi-symmetric finite element model (FEM) vs. a three-dimensional (3-D) FEM for these PWR nozzles. In particular, the ovalization (stress concentration) effect of two intersecting cylinders, which is typical of RPV nozzle configurations, was investigated. To investigate the applicability of previously recommended linear elastic fracture mechanics (LEFM) hand solutions for calculating the Mode I stress intensity factor for a postulated nozzle corner crack for pressure loading for these PWR nozzles. These analyses were performed to further expand earlier work completed to support potential revision and refinement of Title 10 to the U.S. Code of Federal Regulations (CFR), Part 50, Appendix G, Fracture Toughness Requirements, and are intended to supplement similar evaluation of nozzles presented at the 2008, 2009, and 2011 Pressure Vessels and Piping (PVP

  19. State of stress, permeability, and fractures in the Precambrian granite of northern Illinois

    Haimson, Bezalel C.; Doe, Thomas W.


    In situ fracture logging, permeability tests, and stress measurements have been conducted in UPH 3, a 1600-m-deep hole drilled into the Precambrian granitic basement of northern Illinois. Two major fracture zones are revealed, which cannot be discerned in UPH 2, a similarly deep hole about 1 km away. The segments of the UPH 3 core that were oriented indicate the existence of three sets of subvertical joints striking at N55°E, N40°W and E-W. These sets correspond to surface and shallow borehole joint directions in the Precambrian and Paleozoic rock of southern Wisconsin as well as other areas of the Midwest. The permeability values in UPH 3 display an overall reduction with depth from about 10-4 darcy at 700 m to 10-8-10-9 darcy at 1600 m. Permeability is highest in the zones of greatest fracturing, one of which occurs near the top of the granite and is probably related to fractures which were formed when the granite was at the surface in late Paleozoic times. Permeability reduction with depth is consistent with previous laboratory and field results in crystalline rocks. Hydrofracturing measurements in UPH 3 reveal a compressional stress field with the largest stress horizontal and oriented at N48°E (±30°). Based on linear regression of 13 test results in the depth range of 686-1449 m, the greatest horizontal stress has a magnitude of [20.5+(0.023×depth(m))] MPa. The least horizontal compression has a value of [8.7+(0.019×depth(m))] MPa. The vertical stress, based on density measurements, is given by [-1.3+(0.026xdepth(m))] MPa. Both magnitudes and directions support previous results in the technically stable Great Lakes region of the midcontinent. However, a mb = 4.4 earthquake did occur in 1972 some 90 km south of UPH 3, at a depth of 13 km. The focal mechanism solution revealed strike slip motion with the pressure axis horizontal and trending northeast, in accord with our measured stress directions and relative magnitudes but not predicted from a

  20. Regional Flow Simulation in Fractured Aquifers Using Stress-Dependent Parameters

    Preisig, G; Perrochet, P


    A model function relating effective stress to fracture permeability is developed from Hooke's law, implemented in the tensorial form of Darcy's law, and used to evaluate discharge rates and pressure distributions at regional scales. The model takes into account elastic and statistical fracture parameters, and is able to simulate real stress-dependent permeabilities from laboratory to field studies. This modeling approach gains in phenomenology in comparison to the classical ones because the permeability tensors may vary in both strength and principal directions according to effective stresses. Moreover this method allows evaluation of the fracture porosity changes, which are then translated into consolidation of the medium.


    Ji Changjiang; Li Zhonghua; Sun Jun


    A closed-form solution for predicting the tangential stress of an inclusion located in mixed mode Ⅰ and Ⅱ crack tip field was developed based on the Eshelby equivalent inclusion theory. Then a mixed mode fracture criterion, including the fracture direction and the critical load, was established based on the maximum tangential stress in the inclusion for brittle inclusioninduced fracture materials. The proposed fracture criterion is a function of the inclusion fracture stress, its size and volume fraction, as well as the elastic constants of the inclusion and the matrix material. The present criterion will reduce to the conventional one as the inclusion having the same elastic behavior as the matrix material. The proposed solutions are in good agreement with detailed finite element analysis and measurement.

  2. Study of stress adaptability of fracture healing%骨折愈合的应力适应性研究

    董福慧; 关继超; 赵勇; 邹炳曾; 尚天裕


    目的 探讨骨折端受力、肌肉动力、骨痂密度与骨折愈合的关系。方法 通过传感器电测技术与X线灰度分析的方法,从三个方面对骨折愈合的应力适应性进行了研究:①分别对14只1岁龄山羊进行了断端受力与骨折愈合的关系的研究;②对10只健康成年家兔进行了肌肉动力与骨折愈合的关系的研究;③对56只健康成年家兔进行了骨痂密度与骨折愈合的关系的研究。结果与结论 ①理想的骨折愈合与最佳的应力状态相适应;②肌肉动力是应力适应的反馈调节因素;③骨痂密度是应力适应的反馈结果。%Objective To explore the relationship between local stress status,muscular motivation,callus density and fracture healing.Methods Stress adaptability of fracture healing was studied from three respects:1.the relationship between fracture local stress and fracture healing was studied in 14 one year old goats;2.the relationship between muscular motivation and fracture healing was studied in 10 health adult rabbits and 3.the relationship between callus density and fracture healing was studied in 56 healthy adult rabbits.Electric transducer technique and X-ray densitometry method were used in all the three groups of animals.Results and Conclusion 1.Ideal fracture healing should be adapted to the best stress status;2.Muscular motivation is the biofeedback regulation factor of stress adaptability of fracture healing;3.The density of callus is the result of biofeedback of stress adaptability of fracture healing.

  3. Subtrochanteric stress fractures in patients on oral bisphosphonate therapy: an emerging problem.

    Murphy, Colin G


    The emergence of a new variant of subtrochanteric stress fractures of the femur, affecting patients on oral bisphosphonate therapy, has only recently been described. This fracture is often preceded by pain and distinctive radiographic changes (lateral cortical thickening), and associated with a characteristic fracture pattern (transverse fracture line and medial cortical spike). A retrospective review (2007-2009) was carried out for patients who were taking oral bisphosphonates and who sustained a subtrochanteric fracture after a low velocity injury. Eleven fractures were found in 10 patients matching the inclusion criteria outlined. All were females, and taking bisphosphonates for a mean of 43 years. Five of the 10 patients mentioned prodromal symptoms, for an average of 9.4 months before the fracture. Although all fractures were deemed low velocity, 5 of 11 were even atraumatic. Two patients had previously sustained contralateral subtrochanteric fractures. Plain radiographs of two patients showed lateral cortical thickening on the contralateral unfractured femur; the bisphosphonate therapy was stopped and close surveillance was started. Patients taking oral bisphosphonates may be at risk of a new variant of stress fracture of the proximal femur. Awareness of the symptoms is the key to ensure that appropriate investigations are undertaken.

  4. Subtrochanteric stress fractures in patients on oral bisphosphonate therapy: an emerging problem.

    Murphy, Colin G; O'Flanagan, Shay; Keogh, Peter; Kenny, Patrick


    The emergence of a new variant of subtrochanteric stress fractures of the femur, affecting patients on oral bisphosphonate therapy, has only recently been described. This fracture is often preceded by pain and distinctive radiographic changes (lateral cortical thickening), and associated with a characteristic fracture pattern (transverse fracture line and medial cortical spike). A retrospective review (2007-2009) was carried out for patients who were taking oral bisphosphonates and who sustained a subtrochanteric fracture after a low velocity injury. Eleven fractures were found in 10 patients matching the inclusion criteria outlined. All were females, and taking bisphosphonates for a mean of 43 years. Five of the 10 patients mentioned prodromal symptoms, for an average of 9.4 months before the fracture. Although all fractures were deemed low velocity, 5 of 11 were even atraumatic. Two patients had previously sustained contralateral subtrochanteric fractures. Plain radiographs of two patients showed lateral cortical thickening on the contralateral unfractured femur; the bisphosphonate therapy was stopped and close surveillance was started. Patients taking oral bisphosphonates may be at risk of a new variant of stress fracture of the proximal femur. Awareness of the symptoms is the key to ensure that appropriate investigations are undertaken.

  5. Sports fractures.

    DeCoster, T. A.; Stevens, M. A.; Albright, J. P.


    Fractures occur in athletes and dramatically influence performance during competitive and recreational activities. Fractures occur in athletes as the result of repetitive stress, acute sports-related trauma and trauma outside of athletics. The literature provides general guidelines for treatment as well as a variety of statistics on the epidemiology of fractures by sport and level of participation. Athletes are healthy and motivated patients, and have high expectations regarding their level o...

  6. Functional results of osteosynthesis with mini-plate and screws in metacarpal fractures

    Hakan Başar


    Conclusions: Mini-plate and screws fixation of unstable metacarpal fractures produces anatomical reduction of fractures with stabilization that is rigid enough to allow early mobilization, thereby preventing stiffness and hence good functional results.

  7. Stress fracture of the great toe sesamoid in a ballerina: MRI appearance

    Burton, E.M. [Medical Coll. of Georgia, Augusta (United States). Dept. of Radiology; Amaker, B.H. [Medical Coll. of Georgia, Augusta, GA (United States). Dept. of Pathology


    This case is the first to depict a stress fracture of the great toe sesamoid bone using magnetic resonance imaging. We used a 3`` surface coil to produce high resolution images of the sesamoid. (orig.)

  8. Osteomalacia and coxa vara. An unusual co-existence for femoral neck stress fracture

    Kerim Sariyilmaz


    Conclusion: Joint and bone pain without any trauma should be investigated and bone metabolism disorders should be kept in mind. There might be co-existing factors related with stress fractures, and they must be treated simultaneously.

  9. Discrete fracture in quasi-brittle materials under compressive and tensile stress states

    Klerck, PA


    Full Text Available A method for modelling discrete fracture in geomaterials under tensile and compressive stress fields has been developed based on a Mohr-Coulomb failure surface in compression and three independent anisotropic rotating crack models in tension...

  10. Mid-Anterior Tibial Stress Fracture in a Female Elite Athlete : A Case Report.

    Netzer, Patricia A M


    We report the case of an unusual tibial stress fracture and its successful surgical treatment in a female elite sprinter 2 years after complete consolidation of the same tibia following resection of an osteoid osteoma.

  11. Manubrial stress fractures diagnosed on MRI: report of two cases and review of the literature

    Baker, Jonathan C.; Demertzis, Jennifer L. [Washington University School of Medicine, Mallinckrodt Institute of Radiology, Musculoskeletal Section, St Louis, MO (United States)


    In contrast to widely-reported sternal insufficiency fractures, stress fractures of the sternum from overuse are extremely rare. Of the 5 cases of sternal stress fracture published in the English-language medical literature, 3 were in the sternal body and only 2 were in the manubrium. We describe two cases of manubrial stress fracture related to golf and weightlifting, and present the first report of the MR findings of this injury. In each of these cases, the onset of pain was atraumatic, insidious, and associated with increased frequency of athletic activity. Imaging was obtained because of clinical diagnostic uncertainty. On MRI, each patient had a sagittally oriented stress fracture of the lateral manubrium adjacent to the first rib synchondrosis. Both patients had resolution of pain after a period of rest, with subsequent successful return to their respective activities. One patient had a follow-up MRI, which showed resolution of the manubrial marrow edema and fracture line. Based on the sternal anatomy and MR findings, we hypothesize that this rare injury might be caused by repetitive torque of the muscle forces on the first costal cartilage and manubrium, and propose that MRI might be an effective means of diagnosing manubrial stress fracture. (orig.)

  12. Bilateral periprosthetic stress fractures in a juvenile chronic arthritis patient secondary to bilateral genu valgum.

    Al-Khateeb, H; Meir, A; Singer, G C


    Lateral insufficiency fractures following total hip replacement have been reported with the femoral stems positioned in varus, together with osteopenia of the lateral femoral cortex. Any abnormal alignment of the lower limbs, such as genu valgum, will alter the load distribution across the femoral cortices, and repetitive loading during walking will predispose the bones to stress fractures at any stress riser point, such as the tip of a femoral component. Bilateral femoral stress fractures post total hip replacements have not been previously described. We present a 55-year-old woman, diagnosed with juvenile idiopathic arthritis, who had undergone bilateral total hip replacements and bilateral knee replacements. The knees 15 years postoperatively were in valgus and the left knee was extremely stiff, flexing to just 5. The patient presented with bilateral thigh pain, with plain radiographs confirming bilateral periprosthetic fractures of the femur at the tip of well-fixed femoral components. There was no history of injury and her hips were functioning well up to this time. The patient required revision of both hips to long-stem uncemented components, bypassing the fractures, and revision of both knees to stemmed semi-constrained implants, thereby correcting the alignment of both lower limbs. Both fractures healed and the patient is currently pain-free and mobile with walking aids. Surgeons must remain aware that when implants are in situ, abnormal alignments will lead to abnormal forces, and stress fractures are likely to occur at any stress riser around the implant. Avoiding malalignment will avoid this complication.

  13. Pediatric Hip Fractures in California: Results from a Community-Based Hip Fracture Registry.

    Prentice, Heather A; Paxton, Elizabeth W; Hunt, Jessica J; Grimsrud, Christopher D; Weiss, Jennifer M


    Hip fracture registries offer an opportunity to identify and to monitor patients with rare conditions and outcomes, including hip fractures in pediatric patients. To report patient demographics and surgical outcomes of pediatric patients treated surgically for hip fractures in a large integrated health care system. Pediatric patients (fracture) with hip fractures were identified between 2009 and 2012 using our health care system's hip fracture registry. Patient characteristics, type of fracture, surgical treatment, and short-term complications. Among 39 patients identified, 31 (79.5%) were male, and the median age was 15 years old (interquartile range: 11-17 years). Most patients were Hispanic (n = 17, 43.6%) or white (n = 14, 35.9%). There were 8 patients (20.5%) with 15 comorbidities. Delbet Type IV (intertrochanteric) fractures were the most common fracture type (n = 22, 56.4%), and fixation method was equally distributed between intramedullary, screw and sideplate, and screws (n = 12, 30.8% for each). Most surgeries were performed by medium-volume surgeons (n = 22, 56.4%) at medium- and high-volume hospitals (n = 37, 94.9%). Three 90-day readmissions (7.7%), 1 infection (2.6%), 1 malunion (2.6%), and 1 revision (2.6%) were observed in this cohort during the study period. In our series using registry data, hip fractures younger than age 21 years were more common in boys and Hispanic patients. Intertrochanteric fractures (Delbet Type IV) were the most frequently observed type in our community-based hip fracture registry. Short-term complications were infrequent.

  14. FEM analysis of deformation localization mechanisms in a 3-D fractured medium under rotating compressive stress orientations

    Strijker, G.; Beekman, F.; Bertotti, G.; Luthi, S.M.


    Stress distributions and deformation patterns in a medium with a pre-existing fracture set are analyzed as a function of the remote compressive stress orientation (σH) using finite element models with increasingly complex fracture configurations. Slip along the fractures causes deformation localizat

  15. FEM analysis of deformation localization mechanisms in a 3-D fractured medium under rotating compressive stress orientations

    Strijker, G.; Beekman, F.; Bertotti, G.; Luthi, S.M.


    Stress distributions and deformation patterns in a medium with a pre-existing fracture set are analyzed as a function of the remote compressive stress orientation (σH) using finite element models with increasingly complex fracture configurations. Slip along the fractures causes deformation

  16. Spontaneous osteonecrosis of the knee associated with tibial plateau and femoral condyle insufficiency stress fracture

    Narvaez, J.A.; Narvaez, J.; Lama, E.De; Sanchez, A. [Department of Magnetic Resonance Imaging, IDI Hospital Duran i Reynals, Ciutat Sanitaria i Universitaria de Bellvitge, Gran Via s/n, 08907, L' Hospitalet de Llobregat (Barcelona) (Spain)


    The purpose of this article is to describe the association between spontaneous osteonecrosis and insufficiency stress fractures of the knee. To determine whether insufficiency stress fracture is associated with spontaneous osteonecrosis of the knee, we retrospectively reviewed the medical charts and imaging studies of all patients with spontaneous osteonecrosis of the knee, studied by MR imaging, seen in a tertiary hospital over an 8-year period. Four women (age range 66-84 years) presented spontaneous osteonecrosis of the knee associated with insufficiency stress fracture of the medial tibial plateau. One of these patients also presented a concomitant insufficiency stress fracture of the medial femoral condyle. Radiographs were diagnostic of spontaneous osteonecrosis of the medial femoral condyle in three cases, and insufficiency stress fracture of the medial tibial plateau was detected in one case. Magnetic resonance imaging allows the diagnosis of both conditions in all four cases. Spontaneous osteonecrosis of the knee may be associated with insufficiency stress fracture of the medial femoral condyle and the medial tibial plateau. This association provides additional arguments in favor of the traumatic etiology of spontaneous osteonecrosis of knee. (orig.)

  17. Experimental-numerical evaluation of a new butterfly specimen for fracture characterisation of AHSS in a wide range of stress states

    Peshekhodov, I.; Jiang, S.; Vucetic, M.; Bouguecha, A.; Berhens, B.-A.


    Results of an experimental-numerical evaluation of a new butterfly specimen for fracture characterisation of AHHS sheets in a wide range of stress states are presented. The test on the new butterfly specimen is performed in a uniaxial tensile machine and provides sufficient data for calibration of common fracture models. In the first part, results of a numerical specimen evaluation are presented, which was performed with a material model of a dual-phase steel DP600 taken from literature with plastic flow and fracture descriptions. In the second part, results of an experimental-numerical specimen evaluation are shown, which was conducted on another dual-phase steel DP600, which was available with a description of plastic flow only and whose fracture behaviour was characterised in the frame of this work. The overall performance of the new butterfly specimen at different load cases with regard to characterisation of the fracture behaviour of AHSS was investigated. The dependency of the fracture strain on the stress triaxiality and Lode angle as well as space resolution is quantified. A parametrised CrachFEM ductile shear fracture model and modified Mohr-Coloumb ductile shear fracture model are presented as a result of this quantification. The test procedure and results analysis are believed to contribute to current discussions on requirements to AHSS fracture characterisation.

  18. Effects of ball sports on future risk of stress fracture in runners.

    Fredericson, Michael; Ngo, Jessica; Cobb, Kristin


    To evaluate whether playing ball sports during childhood and adolescence is associated with the risk of stress fractures in runners later in life. Retrospective cohort study. National track and field championships, held at Stanford University. One hundred fifty-six elite female and 118 elite male distance runners, age 18 to 44 years. A 1-page questionnaire was used to collect data regarding ages during which athletes played basketball and soccer, as well as other important covariates and outcomes. Athletes reported the ages when stress fractures occurred. Time to event was defined as the number of years from beginning competitive running to the first stress fracture or to current age, if no fracture had occurred. In both men and women, playing ball sports in youth correlated with reduced stress fracture incidence later in life by almost half, controlling for possible confounders. In men, each additional year of playing ball sports conferred a 13% decreased incidence of stress fracture (adjusted hazard ratio [HR] and 95% confidence interval, 0.87 [0.79-0.95]. Among women with regular menses, the HR for each additional year of playing ball sports was similar: 0.87 (0.75-1.00); however, there was no effect of length of time played among women with irregular menses (HR, 1.03 [0.92-1.16]). In men, younger ages of playing ball sports conferred more protection against stress fractures (HR for each 1-year-older age at first exposure, 1.29 [1.14, 1.45]). Runners who participate during childhood and adolescence in ball sports may develop bone with greater and more symmetrically distributed bone mass, and with enhanced protection from future stress fractures.

  19. Treatment of C2 body fracture with unusual distractive and rotational components resulting in gross instability

    Lau, Darryl; Shin, Samuel S.; Patel, Rakesh; Park, Paul


    Cervical fractures can result in severe neurological compromise and even death. One of the most commonly injured segments is the C2 vertebrae, which most frequently involves the odontoid process. In this report, we present the unusual case of a 28-year-old female who sustained a C2 vertebral body fracture (comminuted transverse fracture through the body and both transverse processes) that had both a significant distractive and rotational component, causing the fracture to be highly unstable. ...

  20. Initial Results from the New Stress Map of Texas Project

    Lund Snee, J. E.; Zoback, M. D.


    Modern techniques for characterizing tectonic stress orientation and relative magnitude have been successfully used for more than 35 years. Nevertheless, large areas of North America lack high spatial resolution maps of stress orientation, magnitude, and faulting regime. In Texas, for example, geothermal resources. This year, we launched the Texas Stress Map project to characterize tectonic stress patterns at higher spatial resolution across Texas and nearby areas. Following a successful effort just completed in Oklahoma, we will evaluate borehole breakouts, drilling-induced tensile fractures, shear wave anisotropy, and earthquake data. The principal data source will be FMI (fullbore formation microimager), UBI (ultrasonic borehole imager), cross-dipole sonic, density, and caliper logs provided by private industry. Earthquake moment tensor solutions from the U.S. Geological Survey, Saint Louis University and other sources will also be used. Our initial focus is on the Permian Basin and Barnett Shale petroleum plays due to the availability of data, but we will expand our analysis across the state as the project progresses. In addition, we hope to eventually apply the higher spatial resolution data coverage to understanding tectonic and geodynamic characteristics of the southwestern United States and northeastern Mexico. Here we present early results from our work to constrain stress orientations and faulting regime in and near Texas, and we also provide a roadmap for the ongoing research.

  1. Influence of fractality of fracture surfaces on stress and displacement fields at crack tips


    In the classic theory of fracture mechanics,expressions for calculating the stresses and displacements in the vicinity of the crack tip are deduced on the basis of the assumption that a fracture surface is a smooth surface or that a crack is a smooth crack.In fact,the surface of a crack formed during the fracture is usually very irregular.So the real asymptotic form of the stress and displacement fields at the crack tip is different from the classic one.Considering the irregularity of a real fracture surface or a real crack profile,the crack is taken as a fractal one,and then the real asymptotic form at the crack tip is developed by applying Griffith’s energy balance principle and fractal geometry.Through the developed asymptotic form,it is discovered that the fractality of the crack reduces the stress singularity at the crack tip.

  2. Correlation between Operation Result and Patient Satisfaction of Nasal Bone Fracture.

    Kang, Chang Min; Han, Dong Gil


    Many authors have evaluated the post-reduction result of nasal bone fracture through patient satisfaction or postoperative complications. However, these results are limited because they are subjective. The aim of this study was to correlate an objective operation result with patient satisfaction and postoperative complications according to the type of nasal bone fractures. Our study included 313 patients who had isolated nasal bone fractures and had undergone a closed reduction. Postoperative outcomes were evaluated objectively using computed tomographic (CT) images, while patient satisfaction was evaluated one month after the operation. The correlation of the operation result with patient satisfaction was then evaluated. The correlation between the operation result and patient satisfaction was highest for the lateral impact group type I (LI) type of fracture and lowest for the comminuted fracture group (C) type of fracture. However, there were no statistically significant differences in correlation between the overall result and patient satisfaction by fracture type. The complication rate of lateral impact group type II (LII), C, and frontal impact group type I (FI) fractures were statistically significantly higher than that of frontal impact group type II (FII) and LI fractures. There were no statistically significant relationships between the prevalence of complications and septal fracture or deviation according to the fracture type. In the total group, however, there was a statistically significant difference in complication rate by septal fracture. We found that the CT outcomes correlated with patient satisfaction. The complication rate of LII, C, and FI fractures were statistically significantly higher than that of FII and LI fractures. Septal fracture/deviation increased the postoperative complication in the total group.

  3. Stress dependence of permeability of intact and fractured shale cores.

    van Noort, Reinier; Yarushina, Viktoriya


    Whether a shale acts as a caprock, source rock, or reservoir, understanding fluid flow through shale is of major importance for understanding fluid flow in geological systems. Because of the low permeability of shale, flow is thought to be largely confined to fractures and similar features. In fracking operations, fractures are induced specifically to allow for hydrocarbon exploration. We have constructed an experimental setup to measure core permeabilities, using constant flow or a transient pulse. In this setup, we have measured the permeability of intact and fractured shale core samples, using either water or supercritical CO2 as the transporting fluid. Our measurements show decreasing permeability with increasing confining pressure, mainly due to time-dependent creep. Furthermore, our measurements show that for a simple splitting fracture, time-dependent creep will also eliminate any significant effect of this fracture on permeability. This effect of confinement on fracture permeability can have important implications regarding the effects of fracturing on shale permeability, and hence for operations depending on that.

  4. Traumatic fractures as a result of falls in children and adolescents: A retrospective observational study.

    Wang, Hongwei; Yu, Hailong; Zhou, Yue; Li, Changqing; Liu, Jun; Ou, Lan; Zhao, Yiwen; Song, Guoli; Han, Jianda; Chen, Yu; Xiang, Liangbi


    The aim of this study is to investigate the incidence and pattern of traumatic fractures (TFs) as a result of falls in a population of children and adolescents (≤18 years old) in China.This was a cross-sectional study. We retrospectively reviewed 1412 patients who were children and adolescents with TFs as a result of falls admitted to our university-affiliated hospitals in China from 2001 to 2010. Etiologies included high fall (height ≥2) and low fall (height <2 m). The incidence and pattern were summarized with respect to different age groups, year of admission, etiologies, genders, and the neurological function.This study enrolled 1054 males (74.6%) and 358 females (25.4%) aged 10.8 ± 4.7 years. The etiologies were low fall (1059, 75.0%) and high fall (353, 25.0%). There were 2073 fractures in total and 92 patients (6.5%) presented with multiple fractures. The most common fracture sites were upper extremity fractures in 814 patients (57.6%) and lower extremity fractures in 383 patients (27.1%), followed by craniofacial fractures in 233 patients (16.5%). A total of 231 (16.4%) patients suffered a nerve injury. The frequencies of early and late complications/associated injuries were 19.5% (n = 275) and 9.2% (n = 130). The frequencies of emergency admission, nerve injury, spinal fracture, lower extremity fractures, craniofacial fracture, sternum and rib fracture, and early complications/ASOIs were significantly larger in high fall than low fall (all P <.001, respectively). The frequencies of medical insurance rate (P = .042) and upper extremity fractures (P <.001) were significantly larger in low fall than high fall. The frequencies of spinal fracture (P = .039), lower extremity fractures (P = .048), and craniofacial fracture (P = .041) were significantly larger in female than the male patients. The frequency of upper extremity fractures (P <.001) and the mean age (P <.001) was significantly larger in male than female

  5. Subchondral stress fracture of femoral head in a healthy adult

    Anand Ashish


    Full Text Available Subchondral fracture of the femoral head is an uncommon entity and usually occurs as an insufficiency fracture associated with poor bone quality or as a fatigue fracture in young military recruits. This condition should be considered in the differential diagnosis of acute hip pain in young patients along with transient osteoporosis and avascular necrosis of the hip. We report a case of acute onset hip pain in an asymptomatic healthy adult in which the diagnosis was made by magnetic resonance imaging and the patient responded well to conservative treatment.


    Daniel R. Burns; Nafi Toksoz


    Using a 3-D finite difference method with a rotated-staggered-grid (RSG) scheme we generated synthetic seismograms for a reservoir model consisting of three horizontal layers with the middle layer containing parallel, equally spaced fractures. By separating and analyzing the backscattered signals in the FK domain, we can obtain an estimate of the fracture spacing. The fracture spacing is estimated by taking one-half of the reciprocal of the dominant wavenumber of the backscattered energy in data acquired normal to the fractures. FK analysis for fracture spacing estimation was successfully applied to these model results, with particular focus on PS converted waves. The method was then tested on data from the Emilio Field. The estimated fracture spacing from the dominant wavenumber values in time windows at and below the reservoir level is 25-40m. A second approach for fracture spacing estimation is based on the observation that interference of forward and backscattered energy from fractures introduces notches in the frequency spectra of the scattered wavefield for data acquired normal to the fracture strike. The frequency of these notches is related to the spacing of the fractures. This Spectral Notch Method was also applied to the Emilio data, with the resulting range of fracture spacing estimates being 25-50m throughout the field. The dominant spacing fracture spacing estimate is about 30-40 m, which is very similar to the estimates obtained from the FK method.

  7. Modeling the Fracturing of Rock by Fluid Injection - Comparison of Numerical and Experimental Results

    Heinze, Thomas; Galvan, Boris; Miller, Stephen


    Fluid-rock interactions are mechanically fundamental to many earth processes, including fault zones and hydrothermal/volcanic systems, and to future green energy solutions such as enhanced geothermal systems and carbon capture and storage (CCS). Modeling these processes is challenging because of the strong coupling between rock fracture evolution and the consequent large changes in the hydraulic properties of the system. In this talk, we present results of a numerical model that includes poro-elastic plastic rheology (with hardening, softening, and damage), and coupled to a non-linear diffusion model for fluid pressure propagation and two-phase fluid flow. Our plane strain model is based on the poro- elastic plastic behavior of porous rock and is advanced with hardening, softening and damage using the Mohr- Coulomb failure criteria. The effective stress model of Biot (1944) is used for coupling the pore pressure and the rock behavior. Frictional hardening and cohesion softening are introduced following Vermeer and de Borst (1984) with the angle of internal friction and the cohesion as functions of the principal strain rates. The scalar damage coefficient is assumed to be a linear function of the hardening parameter. Fluid injection is modeled as a two phase mixture of water and air using the Richards equation. The theoretical model is solved using finite differences on a staggered grid. The model is benchmarked with experiments on the laboratory scale in which fluid is injected from below in a critically-stressed, dry sandstone (Stanchits et al. 2011). We simulate three experiments, a) the failure a dry specimen due to biaxial compressive loading, b) the propagation a of low pressure fluid front induced from the bottom in a critically stressed specimen, and c) the failure of a critically stressed specimen due to a high pressure fluid intrusion. Comparison of model results with the fluid injection experiments shows that the model captures most of the experimental

  8. Gas migration model based on overburden strata fracture evolution law in three dimensional mine-induced stress conditions

    Li, Xing; Yin, Guangzhi


    Based on the fracture features obtained from similarity simulation excavation experiment in 3D mine-induced stress condition, the gas migration model in gob area was set up, and numerical simulation using COMSOL Multiphysics software on gas migration law was studied. The research results show that: Gas pressure variety gradient and flow velocity are obviously influenced by fracture distribution shape. Gas concentration distribution presents the rounded rectangle shape in the lower strata, while in higher strata it tends to be a "O shape” morphology which is similar to the fracture form in strata above the gob. Besides, the pressure relief gas mainly accumulates in the working face fracture field, especially in the higher overlying strata. In the compaction field, gas concentration distribution form presents a “saddle” shape morphology in the vertical section, and gas concentration in boundary fracture zone is higher than in the compaction zone. It is remarkable that gas concentration in start-up fractured zone is also relatively high, and with the advance of working face, its gas enrichment degree decreases. The results of the research have an important guiding significance for coal and gas simultaneous extraction.

  9. Influence of shear and deviatoric stress on the evolution of permeability in fractured rock

    Faoro, Igor; Niemeijer, André; Marone, Chris; Elsworth, Derek


    The evolution of permeability in fractured rock as a function of effective normal stress, shear displacement, and damage remains a complex issue. In this contribution, we report on experiments in which rock surfaces were subject to direct shear under controlled pore pressure and true triaxial stress

  10. Influence of shear and deviatoric stress on the evolution of permeability in fractured rock

    Faoro, Igor; Niemeijer, André; Marone, Chris; Elsworth, Derek

    The evolution of permeability in fractured rock as a function of effective normal stress, shear displacement, and damage remains a complex issue. In this contribution, we report on experiments in which rock surfaces were subject to direct shear under controlled pore pressure and true triaxial stress

  11. Principles of management and results of treating the fractured femur during and after total hip arthroplasty.

    Greidanus, Nelson V; Mitchell, Philip A; Masri, Bassam A; Garbuz, Donald S; Duncan, Clive P


    The management of fractures of the femur during and after total hip arthroplasty can be difficult, and treatment can be fraught with complications. The ideal scenario would be one in which these fractures are prevented. It is important that the surgeon has a through understanding of the principles of managing these fractures and has access to a variety of fixation and prosthetic devices and allograft bone when necessary in order to provide the best treatment. Because periprosthetic fractures range from the very simple (requiring no surgical intervention) to the complex (requiring major revision), a classification system of these fractures aids in understanding both the principles of management and results of treatment.

  12. Fracture toughness and evaluation of coating strength with an initial residual stress field

    Byakova, A.V.; Gorbach, V.G. [Polytechnic Institute, Kiev (Ukraine)


    The effect of residual elastic stresses on the geometry of cracks which arise with contact and spontaneous failure of brittle coatings made of high-strength compounds is studied. Conditions are established for the correctness of fracture toughness K{sub lc} tests with indentation of a standard Vickers pyramid as applied to surface layers with an inhomogeneous structure and an initial residual stress field. Taking account of the anisotropy of fracture toughness established by experiment a reliable approach is suggested for evaluating the brittle strength of coatings in the presence of residual stresses.

  13. Information on stress conditions in the oceanic crust from oval fractures in a deep borehole

    Morin, R.H.


    Oval images etched into the wall of a deep borehole were detected in DSDP Hole 504B, eastern equatorial Pacific Ocean, from analysis of an acoustic televiewer log. A systematic inspection of these ovals has identified intriguing consistencies in appearance that cannot be explained satisfactorily by a random, coincidental distribution of pillow lavas. As an alternative hypothesis, Mohr-Coulomb failure criterion is used to account for the generation and orientation of similarly curved, stress-induced fractures. Consequently, these oval features can be interpreted as fractures and related directly to stress conditions in the oceanic crust at this site. The azimuth of the oval center corresponds to the orientation of maximum horizontal principal stress (SH), and the oval width, which spans approximately 180?? of the borehole, is aligned with the azimuth of minimum horizontal principal stress (Sh). The oval height is controlled by the fracture angle and thus is a function of the coefficient of internal friction of the rock. -from Author

  14. 应用J积分断裂准则评价应力吸收层抗裂性能%Evaluation Fracture Resistance of Stress Absorbing Layer Using J-Integral Fracture Criterion

    刘宇; 张肖宁; 薛忠军


    Fracture resistance of three kinds of stress absorbing layers were evaluated based on the J-integral theory of elasticity-plasticity fracture mechanics by semi-circular bending test, and the critical fracture resistance were compared with relative study. It is shown that gap gradation stress absorbing layer has the better fracture resistance. The results indicate that the critical fracture resistance-jCis appropriate to appraise the fracture resistance of stress absorbing layer, and the gap gradation asphalt mixtures with skeleton structure and full asphalt binders can increase its fracture resistance.%应用弹塑性断裂力学J积分理论,采用半圆弯曲试验评价了3种级配应力吸收层的抗裂性能,发现采用断级配设计的应力吸收层具有良好的抗裂性能,结果表明断裂韧度JC可以用来评价应力吸收层的抗裂性能,由丰富沥青胶浆填充断级配骨架结构的级配设计,可以提高沥青混合料的抗裂能力.

  15. Rapid rehabilitation programme following sacral stress fracture in a long-distance running female athlete.

    Knobloch, Karsten; Schreibmueller, Louisa; Jagodzinski, Michael; Zeichen, Johannes; Krettek, Christian


    Stress fractures occur in normal bone due to mechanical overload by cyclic stress increasing the osteoclastic activity, thus facilitating weakening leading to fracture of bones. Long-distance running may lead to stress fractures of the mid- and distal tibia and of the metatarsal bones. Stress fractures to the sacrum are rare. Certain factors for stress fractures in runners have been identified, such as leg-length inequality, a high longitudinal arch of the foot, forefoot varus, and menstrual irregularities in case of female athlete triad. We report on a 22-year-old female runner (usually training 140 km/week) suffering a sacral fatigue-type fracture. The female athlete triad with eating disorders, dysmenorrhea, and osteopenia was ruled out. Sexual hormone blood samples proofed normal values. The diagnosis was performed using magnetic resonance imaging 2 weeks after the onset of buttock pain. A conservative treatment regimen was initiated with strict physical rest for the first 2 weeks, and then gradual increase of physical activity with 60-90 min of daily cycling and moderate 2 x 60 min cross-training. After another 2 weeks time, daily 60-90 min of walking, Nordic pole walking, and moderate strength training two times a week was performed. At 7 weeks running was started, gradually increased to 90 km/week without any pain. A rapid rehabilitation programme after sacral stress fractures involving low impact physical activity, such as Walking and Nordic pole walking, is applicable to female athletes after ruling out the female athlete triad.

  16. Study on Smooth-Blasting Results in Jointed and Fractured Rock


    Factors that affect blasting results may be grouped into those factors that can be controlled and those that cannot be controlled. The controllable factors include explosive properties, initiation timing, and blast geometry. The uncontrollable factors comprise the rock’s natural structures, such as joints and fractures, and the properties, such as elastic constants, density and strength. Among these, the influence of rock structural planes often contributes a high degree of variability to blasting results. This paper presents a theoretical analysis of rock structural plane influences on smooth-blasting results based on elasticity and stress wave propagation theory with an emphasis on smooth blasting techniques. Two types of simulated experiments in lab (using strain and acoustic emission measurements) are used to verify the theoretical analysis. The results show that it is difficult to achieve smooth-blasting results when the angle between the natural rock structural planes and the blast-induced fracture planes ranges from 10° to 60°. Among these angles, 30° is the least desirable angle to produce a smooth wall. For angles less than 10° and greater than 60°, the influence of rock structural planes on blasting results can be ignored.

  17. Evaluating the Risk of a Fifth Metatarsal Stress Fracture by Measuring the Serum 25-Hydroxyvitamin D Levels.

    Shimasaki, Yu; Nagao, Masashi; Miyamori, Takayuki; Aoba, Yukihiro; Fukushi, Norifumi; Saita, Yoshitomo; Ikeda, Hiroshi; Kim, Sung-Gon; Nozawa, Masahiko; Kaneko, Kazuo; Yoshimura, Masafumi


    The fifth metatarsal bone is a common site of stress fractures in soccer athletes. Although several endocrine risk factors for stress fractures have been proposed, the endocrine risks for fifth metatarsal (5-MT) stress fractures have not been evaluated. To evaluate the endocrine risks of fifth metatarsal stress fractures, we conducted a cumulative case-control study. The present study included 37 athletes, of which 18 had a history of a zone 2 or zone 3 fifth metatarsal stress fracture and 19 controls. We analyzed serum 25-hydroxyvitamin D (25-OHD), serum parathyroid hormone (PTH), as well as biochemical markers of bone turnover by univariate or multivariate analyses. Logistic regression analyses adjusted for multiple confounders revealed that insufficient serum 25-OHD levels less than 30 ng/mL (odds ratio [OR], 23.3), higher serum PTH levels (OR, 1.01), or higher serum bone-specific isoform of alkaline phosphatase levels (OR, 1.10) rather than serum tartrate-resistant acid phosphatase 5b were associated with statistically significantly increased odds of 5-MT stress fractures. A postestimation calculation demonstrated that 25-OHD levels of 10 and 20 ng/mL were associated with 5.1 and 2.9 times greater odds for 5-MT stress fractures, respectively. 25-OHD insufficiency was associated with an increased incidence of 5-MT stress fractures. This insight may be useful for intervening to prevent 5-MT stress fractures. Level III, case-control study. © The Author(s) 2015.


    Takeshi Sakata


    Full Text Available Stress fractures of the first rib in athletes are rare. A 14-year-old male, a baseball pitcher who changed from an overhand to a sidearm style, with a stress fracture of the first rib, was reported. Most Stress fractures in the first rib occur at the subclavian groove, between the attachments of the scalenus anterior and scalenus medius muscles, which is the thinnest and weakest portion of the rib. However, in this case the stress fracture occurred at the uncommon region, posterior to the insertion of the scalenus medius muscle, in the first rib. The motion analysis of the pitching in this case demonstrated that the sidearm style induced much more horizontal abduction in the shoulder at the top position than did the overhand style. The findings of electromyography in the serratus anterior muscle, one of the muscles which insert on the first rib, through the pitching motion did not demonstrate any significant differences between the two styles. In this case, the repetition of horizontal over-abduction of the shoulder when sidearm pitching appears to have been the cause of the unusual stress fracture of the first rib at this site

  19. Ductile fracture of metals under triaxial states of stress

    Schrems, Karol Krumrey

    Silver interlayers between maraging steel base metal were examined to evaluate mechanisms leading to ductile failure in constrained thin metals. The constraint of the maraging steel base metal during uniaxial testing of constrained thin silver results in a large hydrostatic tension component, a small von Mises effective stress, and negligible far-field plasticity. The failure theory proposed by Rice and Tracey predicts uniform cavity wall expansion as a result of high triaxiality, in which an increase in plastic strain drives an increase in cavity size. The Rice and Tracey theory predicts significantly greater plastic strain than is experimentally observed. The theory developed by Huang, Hutchinson, and Tvergaard states that a cavitation limit exists at which a cavity continues to grow without an increase in elastic or plastic strain. This occurs when the energy stored in the elastic region is sufficient to drive continued cavity expansion. Inherent in both theories is the assumption of a single cavity in an infinite solid, which implies non-interacting cavities. Modifications have been developed to allow for multiple cavities, but assume pre-existing cavities. By examining silver interlayers previously loaded to various times at a fraction of the tensile strength where time-dependent failure is observed, it was found that some cavities were initially present in the as-bonded samples. Some of the initial cavities were spaced close enough to suggest localized interacting stress fields. This indicates that a failure model should be able to accommodate cavity spacing. The results suggest that cavities are continuously nucleating (from at least the 20 nanometers detectability limit) and grow, sometimes to over 500 nm in diameter. This thesis evaluates the number, size, shape and spacing of cavities in the silver interlayers and uses these results to evaluate ductile failure theories for metals subjected to high triaxial states of stress such as in constrained

  20. The Difference between Growth Factor Expression after Single and Multiple Fractures: Preliminary Results in Human Fracture Healing

    Binder, Harald; Eipeldauer, Stefan; Gregori, Markus; Höchtl-Lee, Leonard; Thomas, Anita; Tiefenboeck, Thomas M.; Hajdu, Stefan; Sarahrudi, Kambiz


    Objectives. Circulating levels of VEGF-A (Vascular Endothelia Growth Factor-A), TGF-β1 (Transforming Growth Factor-beta 1), and M-CSF (Macrophage-Colony Stimulating Factor) were found to be predictors of bone healing and therefore prognostic criteria of delayed bone healing or nonunion. The aim of this study was to evaluate a potential rise of these markers in patients with multiple fractures of long bones compared to patients with single fractured long bone. Methods. 92 patients were included in the study and finally after excluding all female patients 45 male patients were left for final analysis and divided into the single or multiple fracture group. TGF-β1, M-CSF, and VEGF-A serum levels were analysed over a time period of two weeks. Results. MCSF serum concentrations were higher in the group with multiple fractures as also TGF-β1 serum concentrations were at one and two weeks after trauma. No statistically significant difference was observed in the VEGF-A serum concentrations of both groups at either measurement point. Conclusion. We did observe a correlation between the quantity of the M-CSF and TGF-β1 expressions in serum and the number of fractured bones; surprisingly there was no statistically significant difference in the serum levels between patients with single and multiple fractures of long bones. PMID:26246654

  1. High Serum 25-hydroxyvitamin D is Associated with Low Incidence of Stress Fractures


    of Family and Preventive Medicine, School of Medicine, University of California, San Diego, La Jolla, California 3 Osteoporosis Research (p 0.01) (9). Amenorrhea and age older than 25 years were also predictors of increased risk of stress fracture, while history of exercise was... exercise were independently associated with risk of fractures (9). In this study, it was not possible to include amenorrhea and exercise history (prior to

  2. Expedited patient-specific assessment of contact stress exposure in the ankle joint following definitive articular fracture reduction.

    Kern, Andrew M; Anderson, Donald D


    Acute injury severity, altered joint kinematics, and joint incongruity are three important mechanical factors linked to post-traumatic osteoarthritis (PTOA). Finite element analysis (FEA) was previously used to assess the influence of increased contact stress due to joint incongruity on PTOA development. While promising agreement with PTOA development was seen, the inherent complexities of contact FEA limited the numbers of subjects that could be analyzed. Discrete element analysis (DEA) is a simplified methodology for contact stress computation, which idealizes contact surfaces as a bed of independent linear springs. In this study, DEA was explored as an expedited alternative to FEA contact stress exposure computation. DEA was compared to FEA using results from a previously completed validation study of two cadaveric human ankles, as well as a previous study of post-operative contact stress exposure in 11 patients with tibial plafond fracture. DEA-computed maximum contact stresses were within 19% of those experimentally measured, with 90% of the contact area having computed contact stress values within 1MPa of those measured. In the 11 fractured ankles, maximum contact stress and contact area differences between DEA and FEA were 0.85 ± 0.64 MPa and 22.5 ± 11.5mm(2). As a predictive measure for PTOA development, both DEA and FEA had 100% concordance with presence of OA (KL grade ≥ 2) and >95% concordance with KL grade at 2 years. These results support DEA as a reasonable alternative to FEA for computing contact stress exposures following surgical reduction of a tibial plafond fracture.

  3. Stress fractures of the ribs in elite competitive rowers: a report of nine cases

    Dragoni, S. [Institute of Sport Medicine and Science of the Italian Olympic Committee, Department of Radiology, Rome (Italy); Giombini, A.; Ripani, M. [University of Motor Sciences, Department of Health, Rome (Italy); Di Cesare, A. [University of Rome ' ' La Sapienza' ' , Department of Physical Medicine and Rehabilitation, Rome (Italy); Magliani, G. [Medical Department of the Italian State Police, Rome (Italy)


    The objective was to report the clinical and imaging patterns of nine cases of stress fractures of the rib diagnosed in Italian Olympic rowers. Nine patients with stress fractures of the rib detected from 103 (8.7%) Italian team rowers competing between May 2000 and May 2006 were identified based on the database of a sports medicine institute. All athletes were male. They were aged between 17 and 31 years (mean: 24.4). Patient weight, fracture location, rowing side and imaging methods employed were noted. The diagnosis was made based on history, clinical examination and Tc-99m MDP bone scintigraphy. Eight of the 9 fractures were located anterolaterally between the fourth and ninth rib. In 1 of the 5 athletes with standard radiographs, a fracture line was visible and in 4 there was callus formation. In 2 athletes sonography was performed, which detected discontinuity of the rib surface and callus formation (1 case each). Stress fractures of the ribs are relatively common in competitive rowers. They are characterized by increasing lateral chest pain and typical scintigraphic, radiographic and sonographic findings. (orig.)

  4. [The Helkimo index for assessing treatment results after mandibular fractures].

    Härtel, J; Hellmuth, M; Hellmuth, K O


    Based on the Helkimo index we assessed the success of conservative and conservative-surgical forms of treatment for mandibular fractures in a total of 166 patients. The control group consisted of 50 probands. The Helkimo dysfunction index, which is based on various criteria, showed dysfunction in 81.9% of the patients with only slight functional impairment in 57.2% of these cases. 18.1% of the patients were clinically symptom-free. A comparison with the probands revealed no major differences in dysfunction between the two groups. Significant differences were observed only in the case of 2 isolated criteria (maximum mandibular protrusion, muscle pain). Severe dysfunction, however, was more common in the fracture patients. Based on the Helkimo occlusion index disorder were noted in 91.7% of the patients, while severe occlusion disorder were observed particularly in patients with combined mandibular body and condyle fractures (40.0%). In the control group a more favorable occlusion index was found to be due mainly to the greater number of present and/or occluding teeth. The Helkimo index, particularly the dysfunctionindex, is a very useful instrument for assessing the success of treatment measures in mandibular fracture cases. It should be more commonly used to improve the possibilites of objective comparisons between patients from different hospitals.

  5. Rockfall triggering by cyclic thermal stressing of exfoliation fractures

    Collins, Brian; Stock, Greg M.


    Exfoliation of rock deteriorates cliffs through the formation and subsequent opening of fractures, which in turn can lead to potentially hazardous rockfalls. Although a number of mechanisms are known to trigger rockfalls, many rockfalls occur during periods when likely triggers such as precipitation, seismic activity and freezing conditions are absent. It has been suggested that these enigmatic rockfalls may occur due to solar heating of rock surfaces, which can cause outward expansion. Here we use data from 3.5 years of field monitoring of an exfoliating granite cliff in Yosemite National Park in California, USA, to assess the magnitude and temporal pattern of thermally induced rock deformation. From a thermodynamic analysis, we find that daily, seasonal and annual temperature variations are sufficient to drive cyclic and cumulative opening of fractures. Application of fracture theory suggests that these changes can lead to further fracture propagation and the consequent detachment of rock. Our data indicate that the warmest times of the day and year are particularly conducive to triggering rockfalls, and that cyclic thermal forcing may enhance the efficacy of other, more typical rockfall triggers.

  6. Rockfall triggering by cyclic thermal stressing of exfoliation fractures

    Collins, Brian D.; Stock, Greg M.


    Exfoliation of rock deteriorates cliffs through the formation and subsequent opening of fractures, which in turn can lead to potentially hazardous rockfalls. Although a number of mechanisms are known to trigger rockfalls, many rockfalls occur during periods when likely triggers such as precipitation, seismic activity and freezing conditions are absent. It has been suggested that these enigmatic rockfalls may occur due to solar heating of rock surfaces, which can cause outward expansion. Here we use data from 3.5 years of field monitoring of an exfoliating granite cliff in Yosemite National Park in California, USA, to assess the magnitude and temporal pattern of thermally induced rock deformation. From a thermodynamic analysis, we find that daily, seasonal and annual temperature variations are sufficient to drive cyclic and cumulative opening of fractures. Application of fracture theory suggests that these changes can lead to further fracture propagation and the consequent detachment of rock. Our data indicate that the warmest times of the day and year are particularly conducive to triggering rockfalls, and that cyclic thermal forcing may enhance the efficacy of other, more typical rockfall triggers.

  7. Characterization of In-Situ Stress and Permeability in Fractured Reservoirs

    Daniel R. Burns; M. Nafi Toksoz


    Fracture orientation and spacing are important parameters in reservoir development. This project resulted in the development and testing of a new method for estimating fracture orientation and two new methods for estimating fracture spacing from seismic data. The methods developed were successfully applied to field data from fractured carbonate reservoirs. Specific results include: the development a new method for estimating fracture orientation from scattered energy in seismic data; the development of two new methods for estimating fracture spacing from scattered energy in seismic data; the successful testing of these methods on numerical model data and field data from two fractured carbonate reservoirs; and the validation of fracture orientation results with borehole data from the two fields. Researchers developed a new method for determining the reflection and scattering characteristics of seismic energy from subsurface fractured formations. The method is based upon observations made from 3D finite difference modeling of the reflected and scattered seismic energy over discrete systems of vertical fractures. Regularly spaced, discrete vertical fractures impart a ringing coda type signature to seismic energy that is transmitted through or reflected off of them. This signature varies in amplitude and coherence as a function of several parameters including: (1) the difference in angle between the orientation of the fractures and the acquisition direction, (2) the fracture spacing, (3) the wavelength of the illuminating seismic energy, and (4) the compliance, or stiffness, of the fractures. This coda energy is the most coherent when the acquisition direction is parallel to the strike of the fractures. It has the largest amplitude when the seismic wavelengths are tuned to the fracture spacing, and when the fractures have low stiffness. The method uses surface seismic reflection traces to derive a transfer function that quantifies the change in the apparent source

  8. Low back pain during pregnancy caused by a sacral stress fracture: a case report

    Pishnamaz Miguel


    Full Text Available Abstract Introduction Sacral stress fractures are a rare but well known cause of low back pain. This type of fracture has also been observed as a postpartum complication. To date, no cases of intrapartum sacral stress fractures have been described in the literature. Case presentation We report the case of a 26-year-old Caucasian European primigravid patient (30 weeks and two days of gestation who presented to our outpatient clinic with severe low back pain that had started after a downhill walk 14 days previously. She had no history of trauma. A magnetic resonance imaging scan revealed a non-displaced stress fracture of the right lateral mass of her sacrum. Following her decision to opt for non-operative treatment, our patient received an epidural catheter for pain control. The remaining course of her pregnancy was uneventful and our patient gave birth to a healthy child by normal vaginal delivery. Conclusions We conclude that a sacral stress fracture must be considered as a possible cause of low back pain during pregnancy.

  9. Proximal fibular stress fractures in children and adolescents, what should we rely on? Lessons learned from a case.

    de Pina, Carlos Aguiar Ramos; Balacó, Inês; Serrano, Pedro Ruas; Matos, Gabriel


    Fibula fractures are the third most common stress fractures in children and adolescents. The triad of localised periosteal reaction, endosteal thickening and radiolucent cortical lines, localised in the distal third of the fibula along with a typical clinical history is in most cases sufficient to establish the diagnosis. Proximal fibula stress lesions are a very rare finding, with few reports in the literature. Stress fractures in this location demand careful investigation before a definitive diagnosis can be made. In the presence of non-specific MRI findings, stress fracture should be a diagnosis of exclusion. The authors report a case referred to their department by a sports medicine physician with a suspicion of stress fracture of the proximal fibula without characteristic imaging findings, which was ultimately confirmed as a stress lesion only by biopsy.

  10. Patient-specific finite element analysis of chronic contact stress exposure after intraarticular fracture of the tibial plafond.

    Li, Wendy; Anderson, Donald D; Goldsworthy, Jane K; Marsh, J Lawrence; Brown, Thomas D


    The role of altered contact mechanics in the pathogenesis of posttraumatic osteoarthritis (PTOA) following intraarticular fracture remains poorly understood. One proposed etiology is that residual incongruities lead to altered joint contact stresses that, over time, predispose to PTOA. Prevailing joint contact stresses following surgical fracture reduction were quantified in this study using patient-specific contact finite element (FE) analysis. FE models were created for 11 ankle pairs from tibial plafond fracture patients. Both (reduced) fractured ankles and their intact contralaterals were modeled. A sequence of 13 loading instances was used to simulate the stance phase of gait. Contact stresses were summed across loadings in the simulation, weighted by resident time in the gait cycle. This chronic exposure measure, a metric of degeneration propensity, was then compared between intact and fractured ankle pairs. Intact ankles had lower peak contact stress exposures that were more uniform and centrally located. The series-average peak contact stress elevation for fractured ankles was 38% (p = 0.0015; peak elevation was 82%). Fractured ankles had less area with low contact stress exposure than intact ankles and a greater area with high exposure. Chronic contact stress overexposures (stresses exceeding a damage threshold) ranged from near zero to a high of 18 times the matched intact value. The patient-specific FE models represent substantial progress toward elucidating the relationship between altered contact stresses and the outcome of patients treated for intraarticular fractures.

  11. Risk Stratification of Stress Fractures and Prediction of Return-to-Duty


    Award Number: W81XWH-15-C-0024 TITLE: Risk Stratification of Stress Fractures and Prediction of Return -to-Duty PRINCIPAL INVESTIGATOR: Mary L...SUBTITLE Risk Stratification of Stress Fractures and Prediction of Return -to-Duty 5a. CONTRACT NUMBER W81XWH-15-C-0024 Return -to-Duty 5b. GRANT... RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE December 2016 2. REPORT TYPE Annual 3. DATES COVERED 15 Nov 2015- 14 Nov 2016 4. TITLE AND

  12. Experimental Investigation on the Basic Law of the Fracture Spatial Morphology for Water Pressure Blasting in a Drillhole Under True Triaxial Stress

    Huang, Bingxiang; Li, Pengfeng


    The present literature on the morphology of water pressure blasting fractures in drillholes is not sufficient and does not take triaxial confining stress into account. Because the spatial morphology of water pressure blasting fractures in drillholes is not clear, the operations lack an exact basis. Using a large true triaxial water pressure blasting experimental system and an acoustic emission 3-D positioning system, water pressure blasting experiments on cement mortar test blocks (300 mm × 300 mm × 300 mm) were conducted to study the associated basic law of the fracture spatial morphology. The experimental results show that water pressure blasting does not always generate bubble pulsation. After water pressure blasting under true triaxial stress, a crushed compressive zone and a blasting fracture zone are formed from the inside, with the blasting section of the naked drillhole as the center, to the outside. The shape of the outer edges of the two zones is ellipsoidal. The range of the blasting fracture is large in the radial direction of the drillhole, where the surrounding pressure is large, i.e., the range of the blasting fracture in the drillhole radial cross-section is approximately ellipsoidal. The rock near the drillhole wall is affected by a tensile stress wave caused by the test block boundary reflection, resulting in more flake fractures appearing in the fracturing crack surface in the drillhole axial direction and parallel to the boundary surface. The flake fracture is thin, presenting a small-range flake fracture. The spatial morphology of the water pressure blasting fracture in the drillhole along the axial direction is similar to a wide-mouth Chinese bottle: the crack extent is large near the drillhole orifice, gradually narrows inward along the drillhole axial direction, and then increases into an approximate ellipsoid in the internal naked blasting section. Based on the causes of the crack generation, the blasting cracks are divided into three

  13. Atomistic Simulations of Nanotube Fracture

    Belytschko, T; Schatz, G; Ruoff, R S


    The fracture of carbon nanotubes is studied by atomistic simulations. The fracture behavior is found to be almost independent of the separation energy and to depend primarily on the inflection point in the interatomic potential. The rangle of fracture strians compares well with experimental results, but predicted range of fracture stresses is marketly higher than observed. Various plausible small-scale defects do not suffice to bring the failure stresses into agreement with available experimental results. As in the experiments, the fracture of carbon nanotubes is predicted to be brittle. The results show moderate dependence of fracture strength on chirality.

  14. Stress inversion using borehole images and geometry evolution of the fractures in the Rittershoffen EGS project (Alsace, France).

    Azzola, Jérôme; Valley, Benoît; Schmittbuhl, Jean; Genter, Albert; Hehn, Régis


    dataset enabled a consistent evaluation of the in-situ stress field taking place in the underground of the EGS plant, as showed by the comparison to results obtained in the vicinity. Moreover, the study of the evolution of fracturing shows the influence of the stimulation process on the fractures geometry. 1(Baujard, C., Genter, A., Dalmais, E., Maurer, V., Hehn, R., Rosillette, R., Vidal, J., Schmittbuhl, J., 2017). Hydrothermal Characterization of wells GRT-1 and GRT-2 in Rittershoffen, France: Implications on the understanding of natural flow systems in the Rhine Graben, Geothermics, 65, 255-268.

  15. Acoustic Emission Based Surveillance System for Prediction of Stress Fractures


    aging are susceptible to such fractures in contexts of osteoporosis, diabetes, cerebral palsy , fibrous dysplasia and osteogenesis imperfecta. This...until the specimen failed. The test machine recorded the load and displacement data from the load cell and machine actuator displacement, and a second...and eliminated extraneous events which stem from activities other than the formation of microdamage. • Conducted three-point bending tests on

  16. Do Capacity Coupled Electric Fields Accelerate Tibial Stress Fracture Healing


    MJ, Goll SR, Nichols CE, 3rd, Pollack SR: Prevention and treatment of sciatic denervation disuse osteoporosis in the rat tibia with capacitively...the healing of fractures. J Bone Joint Surg Am 83-A:259-70, 2001 40. Rubin CT, McLeod KJ, Lanyon LE: Prevention of osteoporosis by pulsed...USA Corresponding author Belinda R. Beck, Ph.D. Griffith University School of Physiotherapy and Exercise Science, PMB 50 Gold Coast Mail Centre Q

  17. Nondestructive and Localized Measurements of Stress-Strain Curves and Fracture Toughness of Ferritic Steels at Various Temperatures Using Innovative Stress-Strain Microprobe Technology. Final Report for Period 8/13/1996--06/16/1999

    Fahmy M. Haggag


    The results presented in this report demonstrate the capabilities of Advanced Technology Corporation's patented Portable/In Situ Stress-Strain Microprobe (TM) (SSM) System and its Automated Ball Indentation (ABI) test techniques to nondestructively measure the yield strength, the stress-strain curve, and the fracture toughness of ferritic steel samples and components in a reliable and accurate manner.

  18. Treatment of C2 body fracture with unusual distractive and rotational components resulting in gross instability.

    Lau, Darryl; Shin, Samuel S; Patel, Rakesh; Park, Paul


    Cervical fractures can result in severe neurological compromise and even death. One of the most commonly injured segments is the C2 vertebrae, which most frequently involves the odontoid process. In this report, we present the unusual case of a 28-year-old female who sustained a C2 vertebral body fracture (comminuted transverse fracture through the body and both transverse processes) that had both a significant distractive and rotational component, causing the fracture to be highly unstable. Application of halo bracing was unsuccessful. The patient subsequently required a C1-C4 posterior spinal fusion. Follow-up computer tomography imaging confirmed fusion and the patient did well clinically thereafter.


    Daniel R. Burns; M. Nafi Toksoz


    A 3-D elastic wave propagation finite difference model, including effects of attenuation, has been implemented and compared with other existing modeling codes for validation. Models of seismic scattering from discrete large-scale fractures as well as equivalent anisotropic medium representations of small-scale fractures have been generated and used to develop data analysis methods for applications to seismic field data. An inversion scheme has been developed to estimate fracture orientation and fracture density from amplitude variations with offset and azimuth (AVOA). The method has been tested on synthetic data and field data from an offshore fractured carbonate reservoir with promising results. Spectral characteristics of the numerical model data of the seismic wavefield scattered from aligned fractures with different spacing between fracture zones have been analyzed. Results indicate that the spacing of these large, open fracture zones can be estimated from the wavenumber spectra of the scattered wave amplitude as a function of offset in pre-stack data. Two approaches for converting seismically derived fracture parameters into fluid-flow parameters for use in reservoir simulators have been identified. The first is the numerical modeling of Stoke's flow in fracture networks, and the second uses a statistical model of a fracture distribution that allows for the calculation of the elastic properties and permeability tensor of the resulting equivalent medium. These approaches will be compared in the coming year. Multiple meetings have been held with our industry partner, Shell Oil, to identify a field test site for the project. We are focusing our efforts on a fractured carbonate field. The field application test site selection and data transfer will be completed in the coming year.

  20. Evaluation Of Finite Element Mesh Arrangements And Stress Intensity Factor Calculation Methods For Opening Mode Fracture Of Cracked-Cemented Materials

    Hamid R. Nikraz


    Full Text Available Fracture mechanics is a branch of mechanics, which deals with the cracked body. Every construction material that currently in use inevitably is not flawless. The pre-existing crack may grow to cause structure failure due to low stress, which acts to a structure. Stress intensity factor (K is a single parameter in fracture mechanics, which can be used to examine if a crack, would propagate in a cracked structure under particular loading condition. Finite element method is used to analyze the cracked body to provide the displacements data around the crack tip (at quarter point elements due to load prescribed, for stress intensity factor determination. Two methods of stress intensity factor calculation, Quarter Point Displacement Technique (QPDT and Displacement Correlation Technique (DCT, were evaluated. A series of standard fracture testing were undertaken to provide the fracture load data (Pf, which coupled with the stress intensity factor analytical formula to calculate fracture toughness. The results showed that under a particular mesh arrangement, the result of finite element analysis could deviate from the analytical formula calculation result. The QPDT method is suitable for compact tension specimen but DCT seemed to be not. For cracked beam analysis, the QPDT and DCT calculations were in good agreement with the analytical formula as long as coupled with the appropriate mesh arrangement around the crack tip.

  1. Unilateral Pedicle Stress Fracture in a Long-Term Hemodialysis Patient with Isthmic Spondylolisthesis

    Keishi Maruo


    Full Text Available Most unilateral pedicle stress fractures occur on the contralateral side of patients with unilateral spondylolysis. However, there are few reports of unilateral pedicle stress fractures in patients with bilateral spondylolysis and spondylolisthesis. We report a unique case of unilateral pedicle stress fracture in a long-term hemodialysis patient with isthmic spondylolisthesis. A 65-year-old man who had undergone hemodialysis presented with lower back pain that had persisted for several years. The patient experienced severe right lower extremity pain with no history of trauma. Computed tomography revealed unilateral pedicle fracture with bilateral L5 spondylolysis and spondylolisthesis with progression of scoliosis. The patient underwent Gill laminectomy of L5 with pedicle screw fixation at L4-S1 and interbody fusion at L5-S1. The patient’s leg pain ceased immediately, and he began walking without leg pain. In our present patient, development of scoliosis caused by destructive spondyloarthropathy may have contributed to a unilateral pedicle fracture.

  2. Extremely Low-Stress Triaxiality Tests in Calibration of Fracture Models in Metal-Cutting Simulation

    Šebek, František; Kubík, Petr; Petruška, Jindřich; Hůlka, Jiří


    The cutting process is now combined with machining, milling, or drilling as one of the widespread manufacturing operations. It is used across various fields of engineering. From an economical point of view, it is desirable to maintain the process in the most effective way in terms of the fracture surface quality or minimizing the burr. It is not possible to manage this experimentally in mass production. Therefore, it is convenient to use numerical computation. To include the crack initiation and propagation in the computations, it is necessary to implement a suitable ductile fracture criterion. Uncoupled ductile fracture models need to be calibrated first from fracture tests when the test selection is crucial. In the present article, there were selected widespread uncoupled ductile fracture models calibrated with, among others, an extremely low-stress triaxiality test realized through the compression of a cylinder with a specific recess. The whole experimental program together with the cutting process experiment were carried out on AISI 1045 carbon steel. After the fracture models were calibrated and the cutting process was simulated with their use, fracture surfaces and force responses from computations were compared with those experimentally obtained and concluding remarks were made.

  3. The influence of loading conditions on fracture initiation, propagation, and interaction in rocks with veins: Results from a comparative Discrete Element Method study

    Virgo, Simon; Abe, Steffen; Urai, Janos L.


    We present the results of a comparative study of loading conditions on the interactions between extension fractures and veins. We model the fracture behavior of brittle discrete element materials each containing a tabular vein body of variable orientation and strength in two different loading conditions. The first is uniaxial tension, applied with servo-controlled sidewalls. The second is a boudinage boundary condition in which a tensile triaxial stress state is induced in the brittle model volume by quasi-viscous extensional deformation in the adjacent layers. Most of the fracture- vein interactions observed in uniaxial tension also exists in boudinage boundary conditions. However, the importance of each interaction mechanism for a given configuration of relative strength and misorientation of the vein may differ according to the loading mechanism. Nucleation and internal deflection is under both boundary conditions the dominating fracture-vein interaction style in weak veins. In uniaxial tension models, strong veins tend to alter the fracture path by external deflection, while under boudinage loading these veins are more likely overcome by the fracture step over mechanism. Dynamic bifurcation of fractures was observed in uniaxial tension models but never for boudinage boundary conditions. This is because the acceleration of fracture tips in these conditions is suppressed by interaction with distributed fractures as well as viscous damping by the neighboring layers.

  4. The inclusion of weld residual stress in fracture margin assessments of embrittled nuclear reactor pressure vessels

    Dickson, T.L.; Bass, B.R.; McAfee, W.J.


    Analyses were performed to determine the impact of weld residual stresses in a reactor pressure vessel (RPV) on (1) the generation of pressure temperature (P-T) curves required for maintaining specified fracture prevention margins during nuclear plant startup and shutdown, and (2) the conditional probability of vessel failure due to pressurized thermal shock (PTS) loading. The through wall residual stress distribution in an axially oriented weld was derived using measurements taken from a shell segment of a canceled RPV and finite element thermal stress analyses. The P-T curve derived from the best estimate load analysis and a t / 8 deep flaw, based on K{sub Ic}, was less limiting than the one derived from the current methodology prescribed in the ASME Boiler and Pressure Vessel Code. The inclusion of the weld residual stresses increased the conditional probability of cleavage fracture due to PTS loading by a factor ranging from 2 to 4.

  5. Evolution of Deformability and Transport Properties of Fractured Rocks Under the Action of Stress and Chemistry

    Elsworth, Derek; Taron, Josh; Faoro, Igor; Lee, Dae-Sung; Liu, Jishan; Niemeijer, Andre; Yasuhara, Hideaki


    Fluids in the shallow crust exert important controls on a wide spectrum of natural and engineered phenomena. The complex interaction of stress and particularly that of chemistry exhibit important feedbacks which influence the evolution of the mechanical and transport properties of rocks. These feedbacks in turn relate crucially to the subsurface recovery of hydrocarbons from the full spectrum of conventional through unconventional reservoirs, to the recovery of hydrothermal and non-hydrothermal geothermal resources, to the secure and enduring sequestration of energy by-products, and to the earthquake cycle, for example. We report on enigmatic interactions between stress and chemistry in mediating the evolution of permeability and strength in natural and engineered systems pushed far-from equilibrium. These include the roles of excess pore fluid pressures in driving transient changes in permeability and as well as the influence of changes in chemical potential in systems driven far-from-equilibrium. These effects are shown to result in significant changes in permeability that may vary on timescales of minutes to years as feedbacks switch from mechanically-driven to chemically-driven and as the length-scale of the prototype grows. These interactions are explored through coupled modeling including feedbacks in stress and chemistry as relevant to high-carbon through low-carbon energy systems. Examples are selected to illustrate the significance of these interactions in controlling the response of hydrocarbon and geothermal reservoirs, fracture treatments and radioactive waste disposal.

  6. Prevention of brittle fracture of steel structures by controlling the local stress and strain fields

    Moyseychik Evgeniy Alekseevich

    Full Text Available In the article the author offers a classification of the methods to increase the cold resistance of steel structural shapes with a focus on the regulation of local fields of internal stresses and strains to prevent brittle fracture of steel structures. The need of a computer thermography is highlighted not only for visualization of temperature fields on the surface, but also to control the fields of residual stresses and strains in a controlled element.

  7. A case of stress fracture of the femoral neck; Przypadek przeciazeniowego zlamania szyjki kosci udowej

    Walenczak, K.; Widawski, T. [Szpital MSW, Lodz (Poland)


    A case of 28 years-old male with stress fracture of the femoral neck is presented. Heterogeneous clinical picture is blamed for diagnostic problems in the initial stage of the disease. Bone scintigraphy aids in the early diagnosis. The use of low frequency electromagnetic field had unquestionable effect on shortening of the treatment time in the case reported. (author). 10 refs, 1 fig.

  8. Relationship between fracturing nominal stress and porosity for metal foams under biaxial tension

    LIU; Peisheng; (刘培生)


    The relationship between two fracturing nominal stresses and porosity has been put forward for metal foams under biaxial tensile loading, and its mathematical formula is proved to be quite practical with the relative experimental data of the metal foam, which is obtained by electrodeposition method.

  9. Residual stress state in pipe cut ring specimens for fracture toughness testing

    Damjanovic, Darko [J.J. Strossmayer Univ. of Osijek, Slavonski Brod (Croatia). Mechanical Engineering Faculty; Kozak, Drazan [Zagreb Univ. (Croatia). Dept. for Mechanical Design; Marsoner, Stefan [Materials Center, Leoben (Austria).; Gubeljak, Nenad [Maribor Univ. (Slovenia). Chair of Mechanics


    Thin-walled pipes are not suitable for measuring fracture toughness parameters of vital importance because longitudinal crack failure is the most common failure mode in pipes. This is due to the impossibility to manufacture standard specimens for measuring fracture toughness, such as SENB or CT specimens, from the thin wall of the pipe. Previous works noticed this problem, but until now, a good and convenient solution has not been found or developed. To overcome this problem, very good alternative solution was proposed, the so-called pipe ring notched bend specimen (PRNB) [1-5]. Until now, only the idealized geometry PRNB specimen is analyzed, i. e., a specimen which is not cut out from an actual pipe but produced from steel plate. Based on that, residual stresses are neglected along with the imperfections in geometry (elliptical and eccentricity). The aim of this research is to estimate the residual stress state(s) in real pipes used in the boiler industry produced by hot rolling technique. These types of pipes are delivered only in normalized condition, but not stress relieved. Therefore, there are residual stresses present due to the manufacturing technique, but also due to uneven cooling after the production process. Within this paper, residual stresses are estimated by three methods: the incremental hole drilling method (IHMD), X-ray diffraction (XRD) and the splitting method (SM). Knowing the residual stress state in the ring specimen, it is possible to assess their impact on fracture toughness measured on the corresponding PRNB specimen(s).

  10. Displacement and stress fields around rock fractures opened by irregular overpressure variations

    Shigekazu eKusumoto


    Full Text Available Many rock fractures are entirely driven open by fluids such as ground water, geothermal water, gas, oil, and magma. These are a subset of extension fractures (mode I cracks; e.g., dikes, mineral veins and joints referred to as hydrofractures. Field measurements show that many hydrofractures have great variations in aperture. However, most analytical solutions for fracture displacement and stress fields assume the loading to be either constant or with a linear variation. While these solutions have been widely used, it is clear that a fracture hosted by heterogeneous and anisotropic rock is normally subject to loading that is neither constant nor with a linear variation. Here we present new general solutions for the displacement and stress fields around hydrofractures, modelled as two-dimensional elastic cracks, opened by irregular overpressure variations given by the Fourier cosine series. Each solution has two terms. The first term gives the displacement and stress fields due to the average overpressure acting inside the crack; it is given by the initial term of the Fourier coefficients expressing the overpressure variation. The second term gives the displacement and stress fields caused by the overpressure variation; it is given by general terms of the Fourier coefficients and solved through numerical integration. Our numerical examples show that the crack aperture variation closely reflects the overpressure variation. Also, that the general displacement and stress fields close to the crack follow the overpressure variation but tend to be more uniform far from the crack. The present solutions can be used to estimate the displacement and stress fields around any fluid-driven crack, that is, any hydrofracture, as well as its aperture, provided the variation in overpressure can be described by Fourier series. The solutions add to our understanding of local stresses, displacements, and fluid transport associated with hydrofractures in the crust.

  11. In-situ stress and fracture characterization for planning of a hydraulic stimulation in the Desert Peak Geothermal Field, NV

    Hickman, S.; Davatzes, N. C.


    failure could be induced on well-oriented fractures seen in the well once fluid pressures are increased ~2.5 MPa or more above the ambient formation fluid pressure. This includes the intended stimulation interval at 0.9 to 1.1 km depth, which is comprised of rhyolite tuff and argillite at ambient temperatures of ~180 to 195° C. This geomechanical model will be tested during hydraulic stimulation of well 27-15 as part of the Desert Peak EGS Project, which is intended to enhance formation permeability through self-propping shear failure. If this stimulation is successful, then preferential activation of normal faults associated with the current stress state should generate a zone of enhanced permeability propagating to the SSW, in the direction of nearby geothermal injection and production wells, and to the NNE, into an unexploited portion of the field. These results indicate that well 27-15 is a viable candidate for EGS stimulation and complements research by other investigators, including cuttings and core testing, geochemical tracer studies, pressure transient analyses, and micro-seismic monitoring.

  12. The influence of elastic modulus of inlay materials on stress distribution and fracture of premolars.

    Costa, Akf; Xavier, Ta; Noritomi, Py; Saavedra, G; Borges, Als


    SUMMARY The purpose of this study was to evaluate the influence the width of the occlusal isthmus and inlay material had on the stress distribution, displacement, and fracture resistance of upper human premolars. For this in vitro test, 35 intact upper premolars (UPM) were selected and five were kept intact for the control group (group I). The remaining 30 were divided into two experimental groups (n=15) according to the width of isthmus: conservative (CP) and extensive preparation (EP), one third and more than two thirds of cuspal distance, respectively. Five teeth from each experimental group were left without restoration for negative controls (CPnc and EPnc), and the remaining 10 in each group were subdivided according to the inlay material (resin or ceramic): group CPr, CP + indirect resin; group CPc, CP + ceramic; group EPr, EP + indirect resin; and group EPc, EP + ceramic. The cemented inlays were loaded in a universal testing machine at a crosshead speed of 0.5 mm/min until fracture. The fractured specimens were analyzed with stereomicroscopy, and the values of the fracture resistance evaluated by analysis of variance and Tukey test. For the finite element analyses, an average UPM for each group was modeled in Rhinoceros CAD software and imported to Ansys 13.0. An average of 320,000 tetrahedral elements and 540,000 nodes for the seven models were performed using the same experimental simulation setup for each. The models were constrained on the base, and a displacement of 0.02 mm was applied to keep a linear behavior for the analysis. A von Mises stress and total displacement fields were used for the coherence test and the maximum principal stress fields were used for mechanical behavior comparisons. Group I (161.73 ± 22.94) showed a significantly higher mean value than the other experimental groups (EPc: 103.55 ± 15.84; CPc: 94.38 ± 12.35; CPr: 90.31 ± 6.10; EPr: 65.42 ± 10.15; CPnc: 65.46 ± 5.37; EPnc: 58.08 ± 9.62). The stress distribution was

  13. Photoelastic stress analysis assisted evaluation of fracture toughness in hydrothermally aged epoxies

    G. Pitarresi


    Full Text Available The present work has investigated the fracture toughness of a model DGEBA epoxy system subject to Hidro-Thermal aging. A Photoelastic Stress Analysis technique has been implemented, showing the evolution of stresses arising throughout the water uptake process due to the non-uniform swelling of the material. Gravimetric and Dynamic Mechanical Thermal Analyses have further complemented the characterization, showing the onset of plasticization effects with aging. The correlation of all previous characterizations has allowed to conclude that an increase of KIC fracture toughness is obtained at the fully saturated condition. In particular Photoelasticity has also revealed the onset of relevant swelling induced stresses during the first stages of water absorption, leading to an increase of fracture toughness due to compressive stresses settling near the crack tip. A stress free condition is instead reestablished at the later stages of absorption, suggesting that the increased toughness of the saturated material is an effect of the modifications induced by aging on the polymer structure.

  14. Residual strain change resulting from stress corrosion in Carrara marble

    Voigtlaender, Anne; Leith, Kerry; Krautblatter, Michael


    Residual stresses and strains have been shown to play a fundamental role in determining the elastic behavior of engineering materials, yet the effect of these strains on brittle and elastic behavior of rocks remains unclear. In order to evaluate the impact of stored elastic strains on fracture propagation in rock, we undertook a four-month-long three-point bending test on three large 1100 x 100 x 100 mm Carrara Marble samples. This test induced stable low stress conditions in which strains were concentrated at the tip of a saw cut and pre-cracked notch. A corrosive environment was created at the tip of the notch on two samples (M2 and M4) by dripping calcite saturated water (pH ~ 7.5-8). Sample M5 was loaded in the same way, but kept dry. Samples were unloaded prior to failure, and along with an additional non-loaded reference sample (M0), cored into cylindrical subsamples (ø = 50 mm, h = 100 mm) before being tested for changes in residual elastic strains at the SALSA neutron diffractometer at the Institute Laue-Langevin (ILL), Grenoble, France. Three diffraction peaks corresponding to crystallographic planes hkl (110), (104) and (006) were measured in all three spatial directions relative to the notch. Shifts in the diffraction peak position (d) with respect to a strain free state are indicative of intergranular strain, while changes in the width of the peak (FWHM) reflect changes in intragranular strain. We observe distinctly different patterns in residual and volumetric strains in hkℓ (104) and (006) for the dry M5 and wet tested samples (M2 and M4) indicating the presence of water changes the deformation mechanism, while (110) is strained in compression around 200 μstrain in all samples. A broadening of the diffraction peaks (006) and (110) in front of the crack tip is observed in M2 and M4, while M5 shows no changes in the peak width throughout the depth of the sample. We suggest water present at the crack tip increased the rate of corrosion, allowing a

  15. Double Threaded Screw Fixation for Bilateral Stress Fracture of the Medial Malleolus

    Ryo Kanto


    Full Text Available An 18-year-old college basketball player presented with continued ankle pain. A radiographic examination showed bilateral medial malleolus stress fractures. Considering the prolonged history and refractory nature of this injury, surgery was adopted as a treatment option. At surgery, the fracture site was percutaneously fixed using two cannulated double threaded screws. Surgery for each side was sequentially performed two months apart. Prompt bony healing was attained after surgery, and the patient could return to his previous sports level six months after the first surgery without subsequent recurrence.

  16. Stress fractures of the femoral shaft in women's college lacrosse: a report of seven cases and a review of the literature.

    Kang, L; Belcher, D; Hulstyn, M J


    Stress fractures do not often occur in the shaft of the femur. They are more common in the femoral neck, the tibial shaft, the metatarsals, and other bones of the foot. In female athletes, stress fractures classically afflict the distance runner, the ballerina, the gymnast, and the figure skater. To describe the clinical presentation, diagnosis, treatment, and outcome of seven college female lacrosse players with femoral shaft stress fractures, and review the literature. The unusual results of this study support the principle that clinical suspicion should be high when treating any female athlete regardless of the sport. In this case series, an abrupt change in the quality of the running surface during the competitive training season was the only underlying common thread among the athletes. The findings suggest that risk factors for the female athlete are variable and are no longer limited to the undernourished or overtrained.

  17. Combined effects of weld-induced residual stresses and flaws on the fracture strength of Ti-5Al-2.5Sn

    Hall, L. R.


    The combined effects of weld-induced residual stresses and flaws on fracture strength were experimentally evaluated by testing Ti-5Al-2.5Sn surface flawed specimens at -320F (-195C) in liquid nitrogen. Flaws were located in weld metal with crack planes either parallel to or perpendicular to gas tungsten arc weld centerlines, and in base metal with the crack plane perpendicular to the rolling direction. Tests were conducted using two different flaw sizes to effect fracture stresses at two different levels including one level either at or near, and one level well below the tensile yield strength. Three different residual stress levels were generated, measured, and tested. Results were evaluated using modified linear elastic fracture mechanics theory.

  18. Combined effects of weld-induced residual stresses and flaws on the fracture strength of Ti-5Al-2.5Sn

    Hall, L. R.


    The combined effects of weld-induced residual stresses and flaws on fracture strength were experimentally evaluated by testing Ti-5Al-2.5Sn surface flawed specimens at -320F (-195C) in liquid nitrogen. Flaws were located in weld metal with crack planes either parallel to or perpendicular to gas tungsten arc weld centerlines, and in base metal with the crack plane perpendicular to the rolling direction. Tests were conducted using two different flaw sizes to effect fracture stresses at two different levels including one level either at or near, and one level well below the tensile yield strength. Three different residual stress levels were generated, measured, and tested. Results were evaluated using modified linear elastic fracture mechanics theory.

  19. Short- and long-term results following standing fracture repair in 34 horses.

    Payne, R J; Compston, P C


    Standing fracture repair in the horse is a recently described surgical procedure and currently there are few follow-up data. This case series contains 2 novel aspects in the standing horse: repair of incomplete sagittal fractures of the proximal phalanx and medial condylar repair from a lateral aspect. To describe outcome in a case series of horses that had lower limb fractures repaired under standing sedation at Rossdales Equine Hospital. Case records for all horses that had a fracture surgically repaired, by one surgeon at Rossdales Equine Hospital, under standing sedation and local anaesthesia up until June 2011, were retrieved. Hospital records, owner/trainer telephone questionnaire and the Racing Post website were used to evaluate follow-up. Thirty-four horses satisfied the inclusion criteria. Fracture sites included the proximal phalanx (incomplete sagittal fracture, n = 14); the third metacarpal bone (lateral condyle, n = 12, and medial condyle, n = 7); and the third metatarsal bone (lateral condyle, n = 1). One horse required euthanasia due to caecal rupture 10 days post operatively. Twenty horses (66.7% of those with available follow-up) have returned to racing. Where available, mean time from operation to return to racing was 226 days (range 143-433 days). Standing fracture repair produced similar results to fracture repair under general anaesthesia in terms of both the number of horses that returned to racing and the time between surgery and race. Repair of lower limb fracture in the horse under standing sedation is a procedure that has the potential for tangible benefits, including avoidance of the inherent risks of general anaesthesia. The preliminary findings in this series of horses are encouraging and informative when discussing options available prior to fracture repair. © 2012 EVJ Ltd.

  20. Numerical Simulation of Permeability Change in Wellbore Cement Fractures after Geomechanical Stress and Geochemical Reactions Using X-ray Computed Tomography Imaging

    Kabilan, Senthil; Jung, Hun Bok; Kuprat, Andrew P.; Beck, Anthon N.; Varga, Tamas; Fernandez, Carlos A.; Um, Wooyong


    X-ray microtomography (XMT) imaging combined with a three-dimensional (3D) computational fluid dynamics (CFD) modeling technique was used to study the effect of geochemical and geomechanical processes on fracture properties in composite Portland cement–basalt caprock core samples. The effect of fluid properties and flow conditions on fracture permeability was numerically studied by using fluids with varying physical properties and simulating different pressure conditions. CFD revealed that the application of geomechanical stress led to increased fluid flow, which resulted in increased fracture permeability. After CO2-reaction, XMT images displayed preferential precipitation of calcium carbonate within the fractures in the cement matrix and less precipitation in fractures located at the cement–basalt interface. CFD predicted changes in flow characteristics and differences in absolute values of flow properties due to different pressure gradients. CFD was able to highlight the profound effect of fluid properties on flow characteristics and hydraulic properties of fractures. This study demonstrates the applicability of XMT imaging and CFD as powerful tools for characterizing the hydraulic properties of fractures in a number of applications like geologic carbon sequestration and storage, hydraulic fracturing for shale gas production, and enhanced geothermal systems.

  1. Numerical Simulation of Permeability Change in Wellbore Cement Fractures after Geomechanical Stress and Geochemical Reactions Using X-ray Computed Tomography Imaging.

    Kabilan, Senthil; Jung, Hun Bok; Kuprat, Andrew P; Beck, Anthon N; Varga, Tamas; Fernandez, Carlos A; Um, Wooyong


    X-ray microtomography (XMT) imaging combined with three-dimensional (3D) computational fluid dynamics (CFD) modeling technique was used to study the effect of geochemical and geomechanical processes on fracture permeability in composite Portland cement-basalt caprock core samples. The effect of fluid density and viscosity and two different pressure gradient conditions on fracture permeability was numerically studied by using fluids with varying density and viscosity and simulating two different pressure gradient conditions. After the application of geomechanical stress but before CO2-reaction, CFD revealed fluid flow increase, which resulted in increased fracture permeability. After CO2-reaction, XMT images displayed preferential precipitation of calcium carbonate within the fractures in the cement matrix and less precipitation in fractures located at the cement-basalt interface. CFD estimated changes in flow profile and differences in absolute values of flow velocity due to different pressure gradients. CFD was able to highlight the profound effect of fluid viscosity on velocity profile and fracture permeability. This study demonstrates the applicability of XMT imaging and CFD as powerful tools for characterizing the hydraulic properties of fractures in a number of applications like geologic carbon sequestration and storage, hydraulic fracturing for shale gas production, and enhanced geothermal systems.

  2. Primary osteosynthesis augmented with autologous bone graft with total knee arthroplasty in patients with stress fractures of medial femoral condyle with knee osteoarthritis: a cost effective approach

    Vikram Indrajit Shah


    Results: Mean follow-up was 7.0 years. All patients showed statistically significant improvement in their WOMAC total scores (p <0.05. Stress fractures united with good knee alignment. All patients had recovered full range of motion with no pain at the time of final follow-up. No adverse events were noted in any of the patient treated. Conclusions: The present approach is a successful procedure for the elderly population with an arthritic knee with stress fracture of medial femoral condyle. Return to pre-morbid level of functional activity occurs very swiftly. [Int J Res Med Sci 2016; 4(6.000: 2408-2412

  3. Evaluation of Fracture Stress for the SiC Layer of TRISO-Coated Fuel Particles by A Modified Crush Testing

    Byun, Thak Sang [ORNL; Kim, Jin Weon [ORNL; Miller, James Henry [ORNL; Snead, Lance Lewis [ORNL; Hunn, John D [ORNL


    Fracture stress data for the chemical vapor deposition (CVD) SiC coatings of tri-isotropic (TRISO) carbon/silicon carbide coated fuel particles were obtained using a newly developed testing and evaluation method, and their relationship with microstructure investigated. A crush testing technique using a blanket foil at load-transferring contact has been developed for hemispherical shell SiC specimens based on finite element (FE) analysis results. Mean fracture stress varied with test material in the range of 330 650 MPa, and was connected to the combined characteristics of inner surface roughness and porosity.

  4. Seismic monitoring of hydraulic fracturing: techniques for determining fluid flow paths and state of stress away from a wellbore

    Fehler, M.; House, L.; Kaieda, H.


    Hydraulic fracturing has gained in popularity in recent years as a way to determine the orientations and magnitudes of tectonic stresses. By augmenting conventional hydraulic fracturing measurements with detection and mapping of the microearthquakes induced by fracturing, we can supplement and idependently confirm information obtained from conventional analysis. Important information obtained from seismic monitoring includes: the state of stress of the rock, orientation and spacing of the major joint sets, and measurements of rock elastic parameters at locations distant from the wellbore. While conventional well logging operations can provide information about several of these parameters, the zone of interrogation is usually limited to the immediate proximity of the borehole. The seismic waveforms of the microearthquakes contain a wealth of information about the rock in regions that are otherwise inaccessible for study. By reliably locating the hypocenters of many microearthquakes, we have inferred the joint patterns in the rock. We observed that microearthquake locations do not define a simple, thin, planar distribution, that the fault plane solutions are consistent with shear slippage, and that spectral analysis indicates that the source dimensions and slip along the faults are small. Hence we believe that the microearthquakes result from slip along preexisting joints, and not from tensile extension at the tip of the fracture. Orientations of the principal stresses can be estimated by using fault plane solutions of the larger microearthquakes. By using a joint earthquake location scheme, and/or calibrations with downhole detonators, rock velocities and heterogeneities thereof can be investigated in rock volumes that are far enough from the borehole to be representative of intrincis rock properties.


    Daniel R. Burns; M. Nafi Toksoz


    Numerical modeling and field data tests are presented on the Transfer Function/Scattering Index Method for estimating fracture orientation and density in subsurface reservoirs from the ''coda'' or scattered energy in the seismic trace. Azimuthal stacks indicate that scattered energy is enhanced along the fracture strike direction. A transfer function method is used to more effectively indicate fracture orientation. The transfer function method, which involves a comparison of the seismic signature above and below a reservoir interval, effectively eliminates overburden effects and acquisition imprints in the analysis. The transfer function signature is simplified into a scattering index attribute value that gives fracture orientation and spatial variations of the fracture density within a field. The method is applied to two field data sets, a 3-D Ocean Bottom Cable (OBC) seismic data set from an offshore fractured carbonate reservoir in the Adriatic Sea and a 3-D seismic data set from an onshore fractured carbonate field in the Middle East. Scattering index values are computed in both fields at the reservoir level, and the results are compared to borehole breakout data and Formation MicroImager (FMI) logs in nearby wells. In both cases the scattering index results are in very good agreement with the well data. Field data tests and well validation will continue. In the area of technology transfer, we have made presentations of our results to industry groups at MIT technical review meetings, international technical conferences, industry workshops, and numerous exploration and production company visits.

  6. Clinical results after different operative treatment methods of radial head and neck fractures

    Zwingmann, J; Welzel, M; Dovi-Akue, D


    was placed on extracting data describing clinical efficacy and outcome by using the Mason classification and including elbow function scores. A total of 841 clinical studies were identified describing in total the clinical follow-up of 1264 patients. RESULTS: For type II radial head and neck fractures....... If a prosthesis was implanted, the primary implantation seems to be associated with a better outcome after type III (87%) and IV (82%) fractures compared to the results after a secondary implantation. DISCUSSION: Recommendations for surgical treatment of radial head and neck fractures according to the Mason...... the significant best treatment option seems to be ORIF with an overall success rate of 98% by using screws or biodegradable (polylactide) pins. ORIF with a success rate of 92% shows the best results in the treatment of type III fractures and seem to be better than resection and implantation of a prosthesis...

  7. Percutaneous elastic intramedullary nailing of metacarpal fractures: Surgical technique and clinical results study

    Farook Mohamed Z


    Full Text Available Abstract Background We reviewed our results and complications of using a pre-bent 1.6 mm Kirschner wire (K-wire for extra-articular metacarpal fractures. The surgical procedure was indicated for angulation at the fracture site in a true lateral radiograph of at least 30 degrees and/or in the presence of a rotatory deformity. Methods A single K-wire is pre-bent in a lazy-S fashion with a sharp bend at approximately 5 millimeters and a longer smooth curve bent in the opposite direction. An initial entry point is made at the base of the metacarpal using a 2.5 mm drill by hand. The K-wire is inserted blunt end first in an antegrade manner and the fracture reduced as the wire is passed across the fracture site. With the wire acting as three-point fixation, early mobilisation is commenced at the metacarpo-phalangeal joint in a Futuro hand splint. The wire is usually removed with pliers post-operatively at four weeks in the fracture clinic. Results We studied internal fixation of 18 little finger and 2 ring finger metacarpal fractures from November 2007 to August 2009. The average age of the cohort was 25 years with 3 women and 17 men. The predominant mechanism was a punch injury with 5 diaphyseal and 15 metacarpal neck fractures. The time to surgical intervention was a mean 13 days (range 4 to 28 days. All fractures proceeded to bony union. The wire was extracted at an average of 4.4 weeks (range three to six weeks. At an average follow up of 8 weeks, one fracture had to be revised for failed fixation and three superficial wound infections needed antibiotic treatment. Conclusions With this simple and minimally invasive technique performed as day-case surgery, all patients were able to start mobilisation immediately. The general outcome was good hand function with few complications.

  8. Revisiting fracture gradient: Comments on “A new approaching method to estimate fracture gradient by correcting Matthew–Kelly and Eaton's stress ratio”

    Hakiki, Farizal


    A study performed by Marbun et al. [1] claimed that “A new methodology to predict fracture pressure from former calculations, Matthew–Kelly and Eaton are proposed.” Also, Marbun et al.\\'s paper stated that “A new value of Poisson\\'s and a stress ratio of the formation were generated and the accuracy of fracture gradient was improved.” We found those all statements are incorrect and some misleading concepts are revealed. An attempt to expose the method of fracture gradient determination from industry practice also appears to solidify that our arguments are acceptable to against improper Marbun et al.\\'s claims.

  9. Cerebellar infarction resulting from vertebral artery occlusion associated with a Jefferson fracture.

    Muratsu, Hirotsugu; Doita, Minoru; Yanagi, Toshihide; Sekiguchi, Kenji; Nishida, Kotaro; Tomioka, Masao; Kurosaka, Masahiro


    Neurologic deficit secondary to a Jefferson fracture is rare, as the fracture fragments tend to spread outward. To the authors' knowledge, only five cases of vertebral artery injury associated with C1 fracture have been reported. A 75-year-old man with diffuse spinal hyperostosis hit the top of his head and sustained a Jefferson fracture. The patient presented with vertigo and slurred speech. Magnetic resonance (MR) imaging demonstrated cerebellar infarction, and MR angiography (MRA) showed bilateral vertebral artery occlusion associated with a Jefferson fracture. The patient was placed in a halo vest for a total of 11 weeks and treated with anticoagulant therapy. Vertigo gradually improved, and the patient was able to walk with a cane. Previously slurred speech was completely resolved. This case demonstrates that a Jefferson fracture can cause vertebral artery occlusion, resulting in cerebellar infarction. The clinician should be aware of the possibility and implications of vertebral artery injuries, especially if a fracture involving the foramen transversarium with displacement is documented or if there is a neurologic deficit above the level of injury. Advances in noninvasive imaging such as MRA will facilitate accurate evaluation of these potentially life-threatening vascular injuries.

  10. Calcaneal stress fracture: an adverse event following total hip and total knee arthroplasty: a report of five cases.

    Miki, Takaaki; Miki, Takahito; Nishiyama, Akihiro


    Stress fractures have been reported to occur in the pubis, femoral neck, proximal part of the tibia, and fabella during the postoperative period following total knee or total hip arthroplasty. However, to our knowledge, calcaneal stress fractures after total hip or total knee arthroplasty have not been reported in the English-language literature. Most orthopaedic surgeons are not familiar with calcaneal stress fractures that may occur in elderly patients after a total knee or total hip arthroplasty. We retrospectively reviewed the clinical features, imaging findings, and bone mineral content of the proximal part of the femur and the distal end of the radius in five patients who had a calcaneal stress fracture after a total knee or total hip arthroplasty. All patients were women with a mean age of 76.8 years. All fractures occurred in the calcaneus on the same side as the arthroplasty. The fracture appeared at a mean of 10.2 weeks postoperatively. All patients reported heel pain on walking. Swelling and local heat were found in four and three patients, respectively. Pain was elicited by squeezing the calcaneus in all patients. Early radiographs had normal findings in two patients, and an irregular sclerotic line appeared later in the radiographs of all patients. All fractures were treated conservatively. Four fractures healed uneventfully, but one fracture displaced. All patients had osteoporosis. Calcaneal stress fractures during the postoperative period following total knee or total hip arthroplasty may not be as rare as previously thought. Because clinical symptoms of the fracture appear insidiously and radiographic findings are absent or subtle in the early stage, a high index of suspicion is needed for orthopaedic surgeons to make the correct diagnosis. Magnetic resonance imaging or repeated radiographs may be necessary to make the correct diagnosis when no abnormality is apparent on the initial radiograph.

  11. Fractures, stress and fluid flow prior to stimulation of well 27-15, Desert Peak, Nevada, EGS project

    Davatzes, Nicholas C.; Hickman, Stephen H.


    A suite of geophysical logs has been acquired for structural, fluid flow and stress analysis of well 27-15 in the Desert Peak Geothermal Field, Nevada, in preparation for stimulation and development of an Enhanced Geothermal System (EGS). Advanced Logic Technologies Borehole Televiewer (BHTV) and Schlumberger Formation MicroScanner (FMS) image logs reveal extensive drilling-induced tensile fractures, showing that the current minimum compressive horizontal stress, Shmin, in the vicinity of well 27-15 is oriented along an azimuth of 114±17°. This orientation is consistent with the dip direction of recently active normal faults mapped at the surface and with extensive sets of fractures and some formation boundaries seen in the BHTV and FMS logs. Temperature and spinner flowmeter surveys reveal several minor flowing fractures that are well oriented for normal slip, although over-all permeability in the well is quite low. These results indicate that well 27-15 is a viable candidate for EGS stimulation and complements research by other investigators including cuttings analysis, a reflection seismic survey, pressure transient and tracer testing, and micro-seismic monitoring.

  12. Experimental research on overlying strata movement and fracture evolution in pillarless stress-relief mining

    Junhua Xue; Hanpeng Wang; Wei Zhou; Bo Ren; Changrui Duan; Dongsheng Deng


    goaf was bounded by an expansion angle of broken strata in the lateral direction of the retained goaf-side roadway. The spatial and temporal evolution regularities of over-burden’s displacement field and stress field, dynamic development process and distribution of fracture field were analyzed. Based on the simulation results, it is recommended that several goaf drainage methods, i.e. gas drainage with buried pipes in goaf, surface goaf gas drainage, and cross-measure boreholes, should be implemented to ensure the safe mining of the panel 1111(1).

  13. Extension of in-situ stress test analysis to fractured media with reference to Yucca Mountain data

    Davies, J.B.


    Yucca Mountain is underlain by highly fractured rock containing a deep water table. Stress tests have been performed in boreholes in-situ and under high head pressures. For a pre-fractured rock system, data analysis must incorporate the effects of opening and closing of fractures. As the head pressure increases form ambient, the aperture of the existing dilated fractures increase. The fracture surface area remains constant until the excess head increases to above a critical pressure, when induced fractures can open and existing fractures may propagate. These will furnish a larger rock surface area thereby allowing a more rapid percolation of the water into the rock matrix. We have extended previous models by specifying a functional dependence of both existing fracture aperture and induced fracture surface area and volume on the excess water pressure. Relationships are obtained through the mass conservation laws and these predictions are used as discriminative graphs, with the most useful being pressure versus rate of pressure change. Such type-curves are applied to; Yucca Mountain data with interpretation in terms of the applicable fracture systems and the critical pressure. Estimates of the critical pressure are obtained and usually lie in the range of 10 to 30 bars which is appreciably lower than that expected from the lithostatic pressure effects. This implies that large dilational stresses exist at Yucca Mountain.

  14. Fatigue-type stress fractures of the lower limb associated with fibrous cortical defects/non-ossifying fibromas in the skeletally immature

    Shimal, A.; Davies, A.M. [Department of Radiology, Royal Orthopaedic Hospital, Birmingham B31 2AP (United Kingdom); James, S.L.J., E-mail: steven.james@roh.nhs.u [Department of Radiology, Royal Orthopaedic Hospital, Birmingham B31 2AP (United Kingdom); Grimer, R.J. [Department of Orthopaedic Oncology, Royal Orthopaedic Hospital, Birmingham B31 2AP (United Kingdom)


    Aim: To investigate the association of a fatigue-type stress fracture and a fibrous cortical defect/non-ossifying fibroma (FCD/NOF) of the lower limb long bones in skeletally immature patients. Materials and methods: The patient database of a specialist orthopaedic oncology centre was searched to determine the number of skeletally immature patients (<=16 years of age) over an 18 year period with a lower limb long bone lesion ultimately shown to be a fatigue-type stress fracture. The diagnosis was established by a combination of typical imaging findings of a fatigue-type stress fracture, the absence of aggressive features suggestive of a sarcoma (e.g., interrupted periosteal reaction, cortical breach, and a soft-tissue mass) together with evidence of consolidation or healing on follow-up radiographs and resolution of symptoms over the subsequent weeks. The database was also used to determine the number of skeletally immature cases (<=16 years of age) referred in the same period in which the principal lesion was shown to be a fibrous cortical defect (FCD) or non-ossifying fibroma (NOF) of the lower limb long bones. The clinical and imaging features of those cases common to both groups (i.e., with both a fatigue-type stress fracture and a FCD or NOF) were reviewed. Results: Six percent of patients (five cases) referred to an orthopaedic oncology unit, who were subsequently shown to have a stress fracture of the lower limb long bones, were found to have a related FCD/NOF. All had been referred with a suggested diagnosis of a bone sarcoma and/or osteomyelitis. The possibility of a stress fracture had been raised in only one case. Four cases involved the proximal tibia and one the distal femur. Radiographs revealed that both lesions arose in the posteromedial cortex in all but one of the cases. The radiographs and magnetic resonance imaging (MRI) features were considered typical of the overlapping pathological features of the lesions. Conclusions: A sarcoma could be

  15. Distal end radius fractures: evaluation of results of various treatments and assessment of treatment choice

    Vargaonkar Gauresh


    Full Text Available 【Abstract】Objective:The rapid expansion of knowledge regarding the functional anatomy of hand and wrist, increasing functional demands of senior citizens and improved methodologies of achieving and maintaining anatomic restoration of distal radius fractures has generated a renewed interest in addressing these fractures in a more precise manner. The purpose of our study was to evaluate the difference in patients function among those treated by 1 closed reduction and Plaster of Paris cast, 2 distractor application, or 3 open reduction and internal fixation with a volar plate, and to assess the treatment choice for each particular fracture type. Methods: A prospective study was carried out on 60 patients with fractures of the distal end radius. Fractures were classified according to the AO classification into type A (extra-articular, type B (partial articular and type C (complete articular. After initial evaluation patients were taken up for either conservative or operative treatment and were followed up for two years. Results: Anatomical results were evaluated according to the Sarmiento’s modification of Lindstrom Criteria, which showed that excellent results were more frequent with open reduction and internal fixation using the plating technique. Clinical and functional results were evaluated according to the demerit point system of Gartland and Werley with Sarmiento modification, which was revealed to relate with the type of treatment techniques. Conclusion: There is no customized solution for all the fractures of the distal radius. The choice of treatment should be based on the fracture type, the patient’s characteristics, the patient’s demands and the treating surgeon’s experience and preference. Key words: Distal end radius fractures; Volar plate; Radial orthofix

  16. The detection and characterization of natural fractures using P-wave reflection data, multicomponent VSP, borehole image logs and the in-situ stress field determination

    Hoekstra, P. [Coleman Research Corp., Orlando, FL (United States)


    The objectives of this project are to detect and characterize fractures in a naturally fractured tight gas reservoir, using surface seismic methods, borehole imaging logs, and in-situ stress field data. Further, the project aims to evaluate the various seismic methods as to their effectiveness in characterizing the fractures, and to formulate the optimum employment of the seismic methods as regards fracture characterization.

  17. Risk Stratification of Stress Fractures and Prediction of Return to Duty


    provision of law, no person shall be subject to any penalty for fai ling to comply with a collection of information if it does not display a currently valid...include IRB and HRPO approvals for all study protocols, hiring and training of staff at MGH, as well as the initiation of subject recruitment and...enrollment. In study Task 1 we aim to determine the sex- and race-ethnicity-specific bone traits that may contribute to stress fracture risk in military

  18. Fracture resistance and analysis of stress distribution of implant-supported single zirconium ceramic coping combination with abutments made of different materials.

    Firidinoğlu, Kadir; Toksavul, Suna; Toman, Muhittin; Sarikanat, Mehmet; Nergiz, Ibrahim


    The purpose of this study was to compare the fracture resistance and fracture mode of single implant-zirconium coping combinations using zirconium and titanium abutments and to analyze the stress distribution pattern using three-dimensional finite elements analysis. Twenty implants with titanium and zirconium abutments were randomly divided into two groups (n = 10) and into resin blocks. Zirconium copings were cemented onto the abutments. The specimens were loaded with 135° angles to the long axis and the load values at the moment of failure were recorded using a universal test machine. Stress levels were calculated according to the maximum Von Mises criteria. The fracture resistances for titanium and zirconium abutment groups were 525.65 N and 514.05 N, respectively. No significant differences were observed between two groups regarding the fracture resistance levels. The maximum Von Mises equivalent stress concentrated on zirconium copings in both of the groups. Implant-abutment-ZrO2 coping combination has the potential to withstand physiological occlusal forces in the anterior region. Three-dimensional finite elements analysis results of the implant-abutment-ZrO2 coping combination is compatible with the results of fracture resistance.

  19. Rib stress fractures among rowers: definition, epidemiology, mechanisms, risk factors and effectiveness of injury prevention strategies.

    McDonnell, Lisa K; Hume, Patria A; Nolte, Volker


    Rib stress fractures (RSFs) can have serious effects on rowing training and performance and accordingly represent an important topic for sports medicine practitioners. Therefore, the aim of this review is to outline the definition, epidemiology, mechanisms, intrinsic and extrinsic risk factors, injury management and injury prevention strategies for RSF in rowers. To this end, nine relevant books, 140 journal articles, the proceedings of five conferences and two unpublished presentations were reviewed after searches of electronic databases using the keywords 'rowing', 'rib', 'stress fracture', 'injury', 'mechanics' and 'kinetics'. The review showed that RSF is an incomplete fracture occurring from an imbalance between the rate of bone resorption and the rate of bone formation. RSF occurs in 8.1-16.4% of elite rowers, 2% of university rowers and 1% of junior elite rowers. Approximately 86% of rowing RSF cases with known locations occur in ribs four to eight, mostly along the anterolateral/lateral rib cage. Elite rowers are more likely to experience RSF than nonelite rowers. Injury occurrence is equal among sweep rowers and scullers, but the regional location of the injury differs. The mechanism of injury is multifactorial with numerous intrinsic and extrinsic risk factors contributing. Posterior-directed resultant forces arising from the forward directed force vector through the arms to the oar handle in combination with the force vector induced by the scapula retractors during mid-drive, or repetitive stress from the external obliques and rectus abdominis in the 'finish' position, may be responsible for RSF. Joint hypomobility, vertebral malalignment or low bone mineral density may be associated with RSF. Case studies have shown increased risk associated with amenorrhoea, low bone density or poor technique, in combination with increases in training volume. Training volume alone may have less effect on injury than other factors. Large differences in seat and handle

  20. Case of femoral diaphyseal stress fracture after long-term risedronate administration diagnosed by iliac bone biopsy

    Nagai T


    Full Text Available Takashi Nagai, Keizo Sakamoto, Koji Ishikawa, Emi Saito, Takuma Kuroda, Katsunori Inagaki Department of Orthopaedic Surgery, Showa University School of Medicine, Shinagwa-ku, Tokyo, Japan Abstract: Bisphosphonate excessively inhibits bone resorption and results in pathological fracture of the femur or ilium. The subject of this study was administered risedronate for 7 years; we suspected an easy fracture of the femoral diaphysis. In this study, we report the results of this patient's bone biopsy and bone morphometric analysis. A 76-year-old female patient presented with right femoral pain. Bone mineral density of the anteroposterior surface of the 2nd to 4th lumbar vertebrae (L2-L4 was decreased and levels of bone turnover markers were high. Therefore, we initiated treatment with risedronate. As she continued the medication, urinary levels of cross-linked N-terminal telopeptides of type I collagen and alkaline phosphatase (bone-type isozyme were found to be within the normal ranges. After 7 years of administration, the patient experienced pain when she put weight on the right femur and right femoral pain while walking. Plain radiographic examination revealed polypoid stress fracture-like lesions on the right femoral diaphysis and on the slightly distal-lateral cortical bone. Similar lesions were observed on magnetic resonance imaging and bone scintigraphy. We suspected severely suppressed bone turnover. Bone biopsy was obtained after labeling with tetracycline, and bone morphometric analysis was performed. On microscopic examination, slight double tetracycline labeling was observed. The trabeculae were narrow, and the numbers of osteoblasts and osteoclasts were decreased. Further, rates of bone calcification and bone formation were slow. Hence, we diagnosed fracture as a result of low turnover osteopathy. Risedronate was withdrawn, and Vitamin D3 was administered to improve the bone turnover. At 6 months, abnormal signals on magnetic resonance

  1. Numerical Analysis on the Formation of Fracture Network during the Hydraulic Fracturing of Shale with Pre-Existing Fractures

    Jianming He


    Full Text Available In this paper, configurations of pre-existing fractures in cubic rock blocks were investigated and reconstructed for the modeling of experimental hydraulic fracturing. The fluid-rock coupling process of hydraulic fracturing was simulated based on the displacement discontinuities method. The numerical model was validated against the related laboratory experiments. The stimulated fracture configurations under different conditions can be clearly shown using the validated numerical model. First, a dominated fracture along the maximum principle stress direction is always formed when the stress difference is large enough. Second, there are less reopened pre-existing fractures, more newly formed fractures and less shear fractures with the increase of the cohesion value of pre-existing fractures. Third, the length of the stimulated shear fracture decreases rapidly with the increase of the friction coefficient, while the length of the tensile fracture has no correlation to the fiction coefficient. Finally, the increase of the fluid injection rate is favorable to the formation of a fracture network. The unfavorable effects of the large stress difference and the large cohesion of pre-existing fractures can be partly suppressed by an increase of the injection rate in the hydraulic fracturing treatment. The results of this paper are useful for understanding fracture propagation behaviors during the hydraulic fracturing of shale reservoirs with pre-existing fractures.

  2. Influence of operation factors on brittle fracture initiation and critical local normal stress in SE(B) type specimens of VVER reactor pressure vessel steels

    Kuleshova, E. A.; Erak, A. D.; Kiselev, A. S.; Bubyakin, S. A.; Bandura, A. P.


    A complex of mechanical tests and fractographic studies of VVER-1000 RPV SE(B) type surveillance specimens was carried out: the brittle fracture origins were revealed (non-metallic inclusions and structural boundaries) and the correlation between fracture toughness parameters (CTOD) and fracture surface parameters (CID) was established. A computational and experimental method of the critical local normal stress determination for different origin types was developed. The values of the critical local normal stress for the structural boundary origin type both for base and weld metal after thermal exposure and neutron irradiation are lower than that for initial state due to the lower cohesive strength of grain boundaries as a result of phosphorus segregation.

  3. Are the Federal Reserve's Stress Test Results Predictable?

    Paul Glasserman; Gowtham Tangirala


    Regulatory stress tests have become a key tool for setting bank capital levels. Publicly disclosed results for four rounds of stress tests suggest that as the stress testing process has evolved, its outcomes have become more predictable and therefore arguably less informative. In particular, projected stress losses in the 2013 and 2014 stress tests are nearly perfectly correlated for bank holding companies that participated in both rounds. We also compare projected losses across different sce...

  4. Rib stress fracture in a male adaptive rower from the arms and shoulders sport class: case report.

    Smoljanovic, Tomislav; Bojanic, Ivan; Pollock, Courtney L; Radonic, Radovan


    Adaptive rowing is rowing or sculling for rowers with a physical disability. It debuted at the Paralympic Games in 2008. In order to ensure an equitable playing field, rowers with similar levels of physical function and disability are classified into different sport classes for competition. Rowers with an inability to use a sliding seat and impaired trunk function resulting in an inability to perform trunk forward and backward lean via hip flexion/extension are assigned to the Arms and Shoulders (AS) class. AS rowers have to use a chest strap set immediately below the chest in order to localize any trunk movement in AS class. Conditions created by adaptations of rowing equipment and technique within the AS class create unique stresses on the upper thoracic region. The following case report demonstrates how etiology and management of a rib stress fracture in an AS rower differs in comparison to able-body rowers. Of significant importance were the limitations imposed on the rower's ability to maintain rowing-specific fitness, due to the nature of the rib stress fracture and requirement to decrease force transmission through the ribs for several weeks. The rower's gradual return to full training was further impacted by obligatory use of the chest strap, which directly applied pressure over the injured area. Protective orthosis for the chest was designed and applied in order to dissipate pressure of the chest strap over the thorax during rowing (most importantly at the catch position) both on the ergometer and in the boat.

  5. Effect of stress-triaxiality on void growth in dynamic fracture of metals: a molecular dynamics study

    Seppala, E T; Belak, J; Rudd, R E


    The effect of stress-triaxiality on growth of a void in a three dimensional single-crystal face-centered-cubic (FCC) lattice has been studied. Molecular dynamics (MD) simulations using an embedded-atom (EAM) potential for copper have been performed at room temperature and using strain controlling with high strain rates ranging from 10{sup 7}/sec to 10{sup 10}/sec. Strain-rates of these magnitudes can be studied experimentally, e.g. using shock waves induced by laser ablation. Void growth has been simulated in three different conditions, namely uniaxial, biaxial, and triaxial expansion. The response of the system in the three cases have been compared in terms of the void growth rate, the detailed void shape evolution, and the stress-strain behavior including the development of plastic strain. Also macroscopic observables as plastic work and porosity have been computed from the atomistic level. The stress thresholds for void growth are found to be comparable with spall strength values determined by dynamic fracture experiments. The conventional macroscopic assumption that the mean plastic strain results from the growth of the void is validated. The evolution of the system in the uniaxial case is found to exhibit four different regimes: elastic expansion; plastic yielding, when the mean stress is nearly constant, but the stress-triaxiality increases rapidly together with exponential growth of the void; saturation of the stress-triaxiality; and finally the failure.

  6. gunshot fractures of tibia and femur - excellent results with reamed ...


    Oct 10, 2011 ... SIGN intramedullary interlocking nails and grafted with reamed bone marrow give excellent result. ... Literature review revealed that non-union of long .... Wound infection 13.9 % with superficial infection accounting for 11.1 %.

  7. Distal end radius fractures: evaluation of results of various treatments and assessment of treatment choice

    Vargaonkar Gauresh


    Objective:The rapid expansion of knowledge regarding the functional anatomy of hand and wrist,increasing functional demands of senior citizens and improved methodologies of achieving and maintaining anatomic restoration of distal radius fractures has generated a renewed interest in addressing these fractures in a more precise manner.The purpose of our study was to evaluate the difference in patients function among those treated by 1) closed reduction and Plaster of Paris cast,2) distractor application,or 3) open reduction and internal fixation with a volar plate,and to assess the treatment choice for each particular fracture type.Methods:A prospective study was carried out on 60 patients with fractures of the distal end radius.Fractures were classified according to the AO classification into type A (extra-articular),type B (partial articular) and type C (complete articular).After initial evaluation patients were taken up for either conservative or operative treatment and were followed up for two years.Results:Anatomical results were evaluated according to the Sarmiento's modification of Lindstrom Criteria,which showed that excellent results were more frequent with open reduction and internal fixation using the plating technique.Clinical and functional results were evaluated according to the demerit point system of Gartland and Werley with Sarmiento modification,which was revealed to relate with the type of treatment techniques.Conclusion:There is no customized solution for all the fractures of the distal radius.The choice of treatment should be based on the fracture type,the patient's characteristics,the patient's demands and the treating surgeon's experience and preference.

  8. Effect of Base and Inlay Restorative Material on the Stress Distribution and Fracture Resistance of Weakened Premolars.

    Souza, A C O; Xavier, T A; Platt, J A; Borges, A L S


    The purpose of this study was to evaluate the influence of direct base and indirect inlay materials on stress distribution and fracture resistance of endodontically treated premolars with weakened cusps. Forty healthy human premolars were selected; five were left intact as controls (group C+), and the others were subjected to endodontic treatment and removal of buccal and lingual cusp dentin. Five teeth were left as negative controls (group C-). The remaining 30 teeth were divided into two groups according to the direct base material (glass ionomer [GIC] or composite resin [CR]). After base placement, each group was subjected to extensive inlay preparation, and then three subgroups were created (n=5): no inlay restoration (GIC and CR), restored with an indirect composite resin inlay (GIC+IR and CR+IR), and restored with a ceramic inlay (GIC+C and CR+C). Each specimen was loaded until fracture in a universal testing machine. For finite element analysis, the results showed that the removal of tooth structure significantly affected fracture resistance. The lowest values were presented by the negative control group, followed by the restored and based groups (not statistically different from each other) and all lower than the positive control group. In finite element analysis, the stress concentration was lower in the restored tooth compared to the tooth without restoration, whereas in the restored teeth, the stress concentration was similar, regardless of the material used for the base or restoration. It can be concluded that the inlay materials combined with a base showed similar behavior and were not able to regain the strength of intact tooth structure.


    Daniel R. Burns; M. Nafi Toksoz


    During the past six months we have adapted our 3-D elastic, anisotropic finite difference code by implementing the rotated staggered grid (RSG) method to more accurately represent large contrasts of elastic moduli between the fractures and surrounding formation, and applying the perfectly matched layer (PML) absorbing boundary condition to minimize boundary reflections. Two approaches for estimating fracture spacing from scattered seismic energy were developed. The first relates notches in the amplitude spectra of the scattered wavefield to the dominant fracture spacing that caused the scattering. The second uses conventional FK filtering to isolate the backscattered signals and then recovers an estimate of the fracture spacing from the dominant wavelength of those signals. Both methods were tested on synthetic data and then applied to the Emilio field data. The spectral notch method estimated the Emilio fracture spacing to be about 30 to 40 m, while the FK method found fracture spacing of about 48 to 53 m. We continue to work on two field data sets from fractured carbonate reservoirs provided by our industry sponsors--the offshore Emilio Field data (provided by ENIAGIP), and an onshore reservoir from the Middle East (provided by Shell). Calibration data in the form of well logs and previous fracture studies are available for both data sets. In previous reports we showed the spatial distribution fractures in the Emilio Field based on our calculated scattering index values. To improve these results we performed a map migration of all the scattering indices. The results of this migration process show a very strong correlation between the spatial distribution and orientation of our estimated fracture distribution and the fault system in the field. We observe that the scattering index clusters tend to congregate around the fault zones, particularly near multiple faults and at fault tips. We have also processed a swath of data from the second data set (the onshore

  10. On the Relationship between Stress and Elastic Strain for Porous and Fractured Rock

    Liu, Hui-Hai; Rutqvist, Jonny; Berryman, James G.


    Modeling the mechanical deformations of porous and fractured rocks requires a stress-strain relationship. Experience with inherently heterogeneous earth materials suggests that different varieties of Hook's law should be applied within regions of the rock having significantly different stress-strain behavior, e.g., such as solid phase and various void geometries. We apply this idea by dividing a rock body conceptually into two distinct parts. The natural strain (volume change divided by rock volume at the current stress state), rather than the engineering strain (volume change divided by the unstressed rock volume), should be used in Hooke's law for accurate modeling of the elastic deformation of that part of the pore volume subject to a relatively large degree of relative deformation (i.e., cracks or fractures). This approach permits the derivation of constitutive relations between stress and a variety of mechanical and/or hydraulic rock properties. We show that the theoretical predictions of this method are generally consistent with empirical expressions (from field data) and also laboratory rock experimental data.

  11. Treatment of stress fracture of the olecranon in throwing athletes with internal fixation through a small incision

    Fujioka Hiroyuki


    Full Text Available Abstract The present study is a report of retrospective case series of stress fracture of the olecranon. Six patients presented posterior elbow pain in throwing in baseball and softball, but fracture was not diagnosed in radiographs. We detected stress fracture of the olecranon using computed tomographic (CT scan and treated the patient with internal fixation with a headless cannulated double threaded screw through a small skin incision. All patients returned to competitive level without elbow complaints after the operation. When throwing athletes present with unusual posterior elbow pain and no significant findings on radiographs, a CT scan examination should be performed. We recommend surgical treatment of internal fixation with a screw through a small skin incision, as a good option for stress fracture of the olecranon in order to allow early return to sports activity in competitive athletes.

  12. Estimation of return-to-sports-time for athletes with stress fracture – an approach combining risk level of fracture site with severity based on imaging

    Dobrindt Oliver


    Full Text Available Abstract Background The aim was to compare the return-to-sports-time (RTST following stress fractures on the basis of site and severity of injury. This retrospective study was set up at a single institution. Diagnosis was confirmed by an interdisciplinary adjudication panel and images were rated in a blinded-read setting. Methods 52 athletes (female, n = 30; male, n = 22; mean age, 22.8 years with stress fracture (SFX who had undergone at least one examination, either MRI or bone scintigraphy, were included. Magnetic resonance images (MRI and/or bone scintigraphy (BS of SFX were classified as either low- or high-grade SFX, according to existing grading systems. For MRI, high-grade SFX was defined as visibility of a fracture line or bone marrow edema in T1-, T2-weighted and short tau inversion recovery (STIR sequences, with low-grade SFX showing no fracture line and bone marrow edema only in STIR and/or T2-weighted sequences. In BS images, a mild and poorly defined focal tracer uptake represented a low-grade lesion, whereas an intense and sharply marginated uptake marked a high-grade SFX. In addition, all injuries were categorized by location as high- or low-risk stress fractures. RTST was obtained from the clinical records. All patients were treated according to a non-weight-bearing treatment plan and comprehensive follow-up data was complete until full recovery. Two-sided Wilcoxon’s rank sum test was used for group comparisons. Results High-risk SFX had a mean RTST of 132 days (d [IQR 64d – 132d] compared to 119d [IQR 50d – 110d] for low-risk sites (p = 0.19. RTST was significantly longer (p = 0.01 in high-grade lesions [mean, 143d; IQR 66d – 134d] than in low-grade [mean, 95d; IQR 42d – 94d]. Analysis of high-risk SFX showed no difference in RTST (p = 0.45 between high- and low-grade [mean, 131d; IQR 72d – 123d vs. mean, 135d; IQR 63d – 132d]. In contrast, the difference was significant for low-risk SFX

  13. Healing of Stress Fracture in an Animal Model


    performed on cross sections of the midshaft ulna. Periosteal woven bone formation on the periosteal surface resulted from fatigue loading. There was no...panel B (loaded I day microcracks, woven bone (W) on the periosteal surface and resorption spaces before imaging). (R) in the cortex were found 14") showed that and, subsequently, the number of loading cycles to which a tibial aBMD increased by 5.2% in military recruits during a bone is

  14. Thermal/moisture-related stresses and fracture behaviour in solid wood members during forced drying

    Larsen, Finn

    of wood without injury to the timber itself. When solid wood products are dried from a green condition down to an average moisture content level close to the service life conditions of the final product, significant moisture-induced stresses and related fracturing can occur. The drying stresses arise.......e. the possibility of driving mechano-sorptive strains back to their original state, was studied then by use of the verified model. Kiln-drying experiments were carried out, ina specially designed climate chamber under well-defined climatic conditions, allowing the climatic variation limits for crack initiation...... to be identified. The critical tensile stresses were determined by means of simulations and were compared with the levels of tensile strength found in tests of tensile strength carried out at the same temperature levels. Tensile strength is highly dependent upon the temperature! Water flux in the tangential...

  15. Negative magnetic resonance imaging in femoral neck stress fracture with joint effusion: a case report

    Seki, Nobutoshi; Okuyama, Koichiro; Kamo, Keiji; Chiba, Mitsuho [Akita Rosai Hospital, Department of Orthopedic Surgery, Odate, Akita (Japan); Shimada, Yoichi [Akita University School of Medicine, Department of Orthopedic Surgery, Akita (Japan)


    Femoral neck stress fracture (FNSF) is well documented in the orthopedic literature and is generally associated with strenuous activities such as long-distance running and military training. The diagnostic yield of magnetic resonance imaging (MRI) for FNSF was reported to be 100 %, and early MRI is recommended when this fracture is suspected. We encountered a 16-year-old male long-distance runner with FNSF in whom the left femoral neck showed no signal changes on MRI although an effusion was detected in the left hip joint. One month later, roentgenograms revealed periosteal callus and oblique consolidation of the left femoral neck, confirming the diagnosis of compression FNSF. Because FNSF with a normal bone marrow signal on MRI is very rare, this patient is presented here. (orig.)

  16. On the failure analysis of bondlines: Stress or energy based fracture criteria?

    Anyfantis, Konstantinos


    that characterizes a given bondline, both its cohesive strength and fracture toughness material parameters must be experimentally defined. Based on these properties, failure analysis of the bondline can be done either through stress- or energy-based criteria. The aim of this work is to investigate the effectiveness...... of each criteria type to effectively predict debonding initiation/propagation of different bondlines (brittle, quasi-brittle, ductile), which are eventually utilized for the evaluation of the joint's failure load. By representing a bondline according to its cohesive length scale, an effort is made...... experimentation programme. Fracture initiation and propagation of the bondlines was numerically simulated by cohesive zone models. (C) 2014 Elsevier Ltd. All rights reserved....

  17. Early result of hemiarthroplasty in elderly patients with fracture neck of femur

    Mue Daniel


    Full Text Available Background: Fractured neck of femur is a frequent and severe injury in elderly patients with consequent high morbidity and mortality. Hemiarthroplasty is an established treatment modality for displaced intracapsular femoral neck fractures in elderly patients above 60 years. This study analysed the early functional outcome and complications of Austin Moore endoprosthesis in elderly patients above 60 years with fractured neck of femur. Materials and Methods: Retrospective data were obtained over a 5 year period from January 2007 to December 2012. Thirty-five elderly patients of 60 years and above with displaced intracapsular fracture neck of femur treated with hemiarthroplasty using Austin Moore endoprosthesis were included. Data were analysed using SPSS version 21. Results: A total of 35 patients were involved. The age-range was 60-90 years with mean age of 69.7 ΁ 7 years. The predominant mechanism of injury was trivial falls in 18 (66.7% patients. The commonest complication was pressure sore in 2 (5.7% patients, followed by surgical site infection in 1 (2.9% patient and periprosthetic fracture in 1 (2.9% patients. Early post-operative mortality was 2.9%. Post-operative hip functional status according to Postel and Merle d Aubigne revealed that majority (66.6% of patients had satisfactory hip function. Conclusion: Functional outcome of Austin Moore in elderly patients above 60 years with fracture neck of femur was satisfactory in most of the cases with minimal morbidity. Careful patient selection for hemiarthroplasty is vital and may decrease the incidence of complications and ameliorate the outcomes in the treatment of intracapsular femoral neck fractures.

  18. Treatment Results Of Diaphyseal Forearm Fractures With Dynamique Compression Plate A Retrospective study of 156 Cases.

    Hassan BOUSSAKRI


    Full Text Available This retrospective study addresses a series of 156 cases of forearm fractures. These 156 cases were managed in the trauma-orthopedic department (B4 of Fez University Hospital, Morocco, from May 2008 till January 2013. The purpose of this study is to analyze epidemiological and clinical factors of diaphyseal forearm fractures and the results of their treatment with dynamic compression plate (DCP, as well as the complications and therapeutic errors of this surgical technique. The frequency of hospitalization in the trauma-orthopedic department was 3,96%. Ages ranged between 16 and 83, the average age was 32. 132 patients were male (85%. 90% were managed at the day of trauma. Traffic accidents were the most frequent cause in 52% patients. The fracture was in the left forearm in 65% of patients. 53% of fracture lines were in the middle third of the forearm. 38 fractures were open, and 30 were admitted for polytrauma. Osteosynthesis was performed with dynamic compression plate for all patients. In comparison with the literature, our series shows the predominance of young male patients, with traffic accidents being the cause. Osteosynthesis with dynamic compression plate remains the treatment of choice that provides satisfactory results if the accuracy in this technique was respected.

  19. Distal Femoral Locking Compression Plate Fixation in Distal Femoral Fractures: Early Results

    EJ Yeap


    Full Text Available We conducted a retrospective review on eleven patients who were treated for Type A and C distal femoral fractures (based on AO classification between January 2004 and December 2004. All fractures were fixed with titanium distal femoral locking compression plate. The patient’s ages ranged from 15 to 85 with a mean of 44. Clinical assessment was conducted at least 6 months post-operatively using the Schatzker scoring system. Results showed that four patients had excellent results, four good, two fair and one failure.

  20. Treatment of proximal humeral fractures using anatomical locking plate: correlation of functional and radiographic results

    Antonio Carlos Tenor Junior


    Full Text Available ABSTRACT OBJECTIVE: To correlate the functional outcomes and radiographic indices of proximal humerus fractures treated using an anatomical locking plate for the proximal humerus. METHODS: Thirty-nine patients with fractures of the proximal humerus who had been treated using an anatomical locking plate were assessed after a mean follow-up of 27 months. These patients were assessed using the University of California Los Angeles (UCLA score and their range of motion was evaluated using the method of the American Academy of Orthopedic Surgeons on the operated shoulder and comparative radiographs on both shoulders. The correlation between radiographic measurements and functional outcomes was established. RESULTS: We found that 64% of the results were good or excellent, according to the UCLA score, with the following means: elevation of 124°; lateral rotation of 44°; and medial rotation of thumb to T9. The type of fracture according to Neer's classification and the patient's age had significant correlations with the range of motion, such that the greater the number of parts in the fracture and the greater the patient's age were, the worse the results also were. Elevation and UCLA score were found to present associations with the anatomical neck-shaft angle in anteroposterior view; fractures fixed with varus deviations greater than 15° showed the worst results (p < 0.001. CONCLUSION: The variation in the neck-shaft angle measurements in anteroposterior view showed a significant correlation with the range of motion; varus deviations greater than 15° were not well tolerated. This parameter may be one of the predictors of functional results from proximal humerus fractures treated using a locking plate.

  1. Results of titanium elastic nailing in paediatric femoral diaphyseal fractures-report of 30 cases

    Jalan Divesh


    Full Text Available 【Abstract】 Objective: Fractures of the femur are the most incapacitating fractures. For children aged 6-14 years, there is no clear consensus as to the preferred treatment. The conventional treatment of traction and cast-ing is no longer recommended. We report our experience in titanium elastic nailing for treatment of paediatric femoral diaphyseal fractures. Methods: Thirty patients in the age group of 6-16 years with displaced diaphyseal femoral fractures were sta-bilized with titanium elastic nails. Patients were followed up clinically and radiologically for a minimum period of 1 year. The final results were evaluated using Flynn’s criteria. Tech-nical difficulties and complications associated with the pro-cedure were also analysed. Results: Overall results were excellent in 20 cases and satisfactory in 10 cases. No patient had poor result. The average hospital stay was 9 days. All the fractures healed with an average time to union of 6.86 weeks. The most com-mon complication encountered was soft tissue irritation at the nail entry site seen in 6 cases. Clinically, lengthening was noticed in 4 cases, while no patient had shortening. Malalignment was seen in only 6 cases. Perioperative diffi-culties encountered were failure of closed reduction seen in 6 cases and corkscrewing of nails in one case. Conclusion: Titanium elastic nails are a relatively easy to use, minimally invasive, physeal-protective implant sys-tem with high rate of good and excellent outcomes in chil-dren aged 6-16 years. Technical pitfalls can be eliminated by adhering to the basic principles. Key words: Titanium; Nails; Fractures, bone; Femur; Paediatrics

  2. Do stress fractures induce hypertrophy of the grafted fibula? A report of three cases received free vascularized fibular graft treatment for tibial defects

    Yong Qi; Hong-Tao Sun; Yue-Guang Fan; Fei-Meng Li; Zhou-Sheng Lin


    The presence of large segmental defects of the diaphyseal bone is challenging for orthopedic surgeons.Free vascularized fibular grafting (FVFG) is considered to be a reliable reconstructive procedure.Stress fractures are a common complication following this surgery,and hypertrophy is the main physiological change of the grafted fibula.The exact mechanism of hypertrophy is not completely known.To the best of our knowledge,no studies have examined the possible relationship between stress fractures and hypertrophy.We herein report three cases of patients underwent FVFG.Two of them developed stress fractures and significant hypertrophy,while the remaining patient developed neither stress fractures nor significant hypertrophy.This phenomenon indicates that a relationship may exist between stress fractures and hypertrophy of the grafted fibula,specifically,that the presence of a stress fracture may initiate the process of hypertrophy.

  3. Do stress fractures induce hypertrophy of the grafted fibula? A report of three cases received free vascularized fibular graft treatment for tibial defects.

    Qi, Yong; Sun, Hong-Tao; Fan, Yue-Guang; Li, Fei-Meng; Lin, Zhou-Sheng


    The presence of large segmental defects of the diaphyseal bone is challenging for orthopedic surgeons. Free vascularized fibular grafting (FVFG) is considered to be a reliable reconstructive procedure. Stress fractures are a common complication following this surgery, and hypertrophy is the main physiological change of the grafted fibula. The exact mechanism of hypertrophy is not completely known. To the best of our knowledge, no studies have examined the possible relationship between stress fractures and hypertrophy. We herein report three cases of patients underwent FVFG. Two of them developed stress fractures and significant hypertrophy, while the remaining patient developed neither stress fractures nor significant hypertrophy. This phenomenon indicates that a relationship may exist between stress fractures and hypertrophy of the grafted fibula, specifically, that the presence of a stress fracture may initiate the process of hypertrophy.

  4. A cross-sectional study of the effects of load carriage on running characteristics and tibial mechanical stress: implications for stress fracture injuries in women


    Orthop Surg. 2000;8(6):344–53. 3. Brukner P, Bradshaw C, Khan KM, White S, Crossley K. Stress fractures: a review of 180 cases. Clin J Sport Med. 1996;6(2...85–9. 4. Fredericson M, Bergman AG, Hoffman KL, Dillingham MS. Tibial stress reaction in runners. Correlation of clinical symptoms and scintigraphy... Stress fracture risk factors in basic combat training. Int J Sports Med. 2012;33(11):940–6. doi:10. 1055/s-0032-1311583. 6. Jones BH, Perrotta DM

  5. [Periprosthetic Femoral Fractures after Total Hip Replacement: Our Results and Treatment Complications].

    Pavelka, T; Salášek, M; Weisová, D


    PURPOSE OF THE STUDY The study consists of a retroactive evaluation of results of surgical treatment in patients with periprosthetic femoral fracture after total hip replacement and a comparison with results reported in the literature. MATERIAL AND METHODS In the period from 2003 to 2013, a total of 83 patients with periprosthetic femoral fracture after total hip replacement were treated at our clinic, namely 69 women and 14 men. The mean age in the cohort was 74 years (range 47-87). The Vancouver classification was used to grade the fractures. The cohort included 31 patients with type B1 fracture, 25 patients with type B2 fracture, 8 patients with type B3 fracture, and 19 patients with type C fracture. Altogether 80 patients underwent a surgery, 3 patients with non-displaced type B1 fracture were treated conservatively. The mechanism of injury was a simple fall in 75 % of primary endoprostheses and in 56% of revision endoprostheses. The average time to fracture was 7.6 years in primary implant and 3.6 years in revision endoprosthesis. In fractures with a well-fixed stem (type B1 and C) plate osteosynthesis was used. In case of a comminution zone, osteosynthesis was followed by spongioplasty. In patients with a loose stem (type B2 and B3), the fracture was treated with a revision uncemented stem. In two cases a combination of a revision stem and a massive corticocancellous bone graft was used. The evaluation was performed using the Harris Hip Score and the minimum follow-up from the surgery was 3 years. RESULTS In the group of patients with type B1 fracture, 28 patients were treated surgically. An excellent result was achieved in 22 patients (84%), in 4 patients (16%) the result was very good. The remaining 2 patients failed to meet the requirement of the minimum follow-up of 3 years. In the group of patients with type B2 fractures, composed of 25 patients, the femoral component was replaced with a revision uncemented stem with cerclage wires or titanium tapes or

  6. Patient characteristics and outcomes of a hip fracture and concomitant fracture compared with hip fracture alone: results from a United Kingdom teaching hospital.

    Ong, Terence; Anand, Varun; Tan, Wei; Quah, Edmund; Moran, Chris; Sahota, Opinder


    A proportion of patients sustaining hip fractures present with a concomitant fracture. We aimed to evaluate the relationship between patient characteristics and clinical outcomes, in those with a hip and concomitant fracture compared with those sustaining a hip fracture alone from a clinical service registry. Cross-sectional study using data obtained from a clinical service registry (Nottingham Hip Fracture Database) on patients aged 50 and above who suffered a hip fracture between 1/1/2003 and 31/12/2012. Data was collected on patient demographics, fracture information and healthcare outcomes. 7338 patients of which 75 % were female (mean age 82 (SD 9.4), had a hip fracture with 334 (4.6 %) patients having a concomitant fracture. The majority (58 %) were distal radius or proximal humeral fractures. Only females (p = 0.002), those taking three or fewer medications (p = 0.018) and those on long term steroids (p = 0.048) were more likely to suffer a concomitant fracture. There was no difference in mortality, rates of postoperative complication, intensive care unit or care home admission between both groups. Patients with a concomitant fracture have a 16 % longer average length of stay in hospital (mean difference 1.16; 95 % CI 1.07-1.25, p fractures have similar patient characteristics, except gender, polypharmacy and long term steroid use; and outcomes to those presenting with hip fracture alone, except a longer average inpatient stay.


    Cohen, Marcio; Amaral, Marcus Vinicius; Monteiro, Martim; Brandão, Bruno Lobo; Motta Filho, Geraldo Rocha


    Describe the results of proximal humeral fractures surgically treated with the Philos locking plate system. Method: Between March 2003 and October 2004 we prospectively reviewed 24 of 26 patients with proximal humerus fractures treated with a Philos plate. The mean follow-up time was 12 months and the mean age of patients was 57 years. Six patients had four-part proximal humerus fractures, 11 patients had three-part proximal humerus fractures, and nine patients had two-part proximal humerus fractures. Clinical evaluation was performed using the University of California at Los Angeles (UCLA) criteria. Results: The mean UCLA score was 30 points (17-34). All fractures showed union. Three patients showed fracture union at varus position. The mean UCLA score for these patients was 27 points. Conclusion: Osteosynthesis with Philos plate provides a stable fixation method with good functional outcome. PMID:26998460

  8. Evaluation of models for estimating changes in fracture permeability due to thermo-mechanical stresses in host rock surrounding a potential repository

    Berge, P A; Blair, S C; Shaffer, R J; Wang, H F


    We provide in this report a methodology to estimate bounds on the changes in fracture permeability due to thermal-mechanical processes associated with excavation of drifts and emplacement of waste. This report is the first milestone associated with Task A of the LLNL initiative to evaluate available methods for estimating chamges in fracture permeability surrounding drifts in the Exploratory Studies Facility (ESF) and the potential repository at Yucca Mountain in response to (1) construction-induced stress changes and (2) subsequent thermal pulse effects due to waste emplacement. These results are needed for modeling changes in repository-level moisture movement and seepage.

  9. One-year results of cemented bipolar radial head prostheses for comminuted radial head fractures

    Laun, Reinhold


    Full Text Available Introduction: Comminuted radial head fractures (Mason type III continue to pose a challenge to orthopedic surgeons. When internal fixation is not possible, radial head arthroplasty has been advocated as the treatment of choice. The purpose of this retrospective study was to evaluate clinical and radiological short-term results of patients with Mason type III radial head fractures treated with a cemented bipolar radial prosthesis. Methods: Twelve patients received cemented bipolar radial head hemiarthroplasty for comminuted radial head fractures. In all patients a CT scan was obtained prior to surgical treatment to assess all associated injuries. Postoperatively an early motion protocol was applied. All patients were evaluated clinically and radiologically at an average of 12.7 months.Results: According to the Mayo Modified Wrist Score, the Mayo Elbow Performance Score, the functional rating index of Broberg and Morrey, and the DASH Score good to excellent results were obtained. Grip strength and range of motion were almost at the level of the unaffected contralateral side. Patient satisfaction was high, no instability or signs of loosening of the implant, and only mild signs of osteoarthritis were seen.Conclusion: Overall good to excellent short-term results for primary arthroplasty for comminuted radial head fractures were observed. These encouraging results warrant the conduction of further studies with long-term follow-up and more cases to see if these short-term results can be maintained over time.

  10. Estimation of 2-D and 3-D Fracture Densities from 1-D Data Experimental and Field Results

    XU Jiandong; Robert D. JACOBI


    2-D and 3-D densities of fractures are commonly used in mining safety design, natural gas and oil productionin fractured reservoirs, and the characterization of subsurface flow and transportation systems in fractured rocks. However,many field data sets are collected in 1-D frequency (f) (e.g., scanlines and borehole data). We have developed an ARC/INFO-based technology to calculate fracture frequency and densities for a given fracture network. A series of numericalsimulations are performed in order to determine the optimal orientation of a scanline, along which the maximum fracturefrequency of a fracture network can be obtained. We calculated the frequency (f) and densities (both D1 and D2) of 36natural fracture trace maps, and investigated the statistical relationship between fracture frequency and fracture density D1,i.e. D1=l.340f + 0.034. We derived analytical solutions for converting dimensional density (D1) to non-dimensionaldensities (D2 and D3) assuming that fracture length distribution follows an exponential or power law. A comparisonbetween observed and calculated results based on the equations we developed shows that (1) there exists a linearrelationship between fracture frequency and fracture density (D1), and this relationship can be used to estimate fracturedensity (D1) if the fracture frequency is determined from a scanline survey or from borehole data; (2) the analyticalsolutions we derived can accurately determine the non-dimensional 2-D fracture density (D2) in practice and 3-D fracturedensity (D3) in theory if the fracture length distribution function is assumed.

  11. Maximum length of large diameter Czochralski silicon single crystals at fracture stress limit of seed

    Kim, K. M.; Smetana, P.


    Growth of large diameter Czochralski (CZ) silicon crystals require complete elimination of dislocations by means of Dash technique, where the seed diameter is reduced to a small size typically 3 mm in conjunction with increase in the pull rate. The maximum length of the large CZ silicon is estimated at the fracture stress limit of the seed neck diameter ( d). The maximum lengths for 200 and 300 mm CZ crystals amount to 197 and 87 cm, respectively, with d = 0.3 cm; the estimated maximum weight is 144 kg.

  12. Scaphoid Stress Fracture in High-Level Gymnast: A Case Report

    J. C. Nakamoto


    Full Text Available We present the case of an 18-year-old high-level gymnast who sustained a stress fracture of the scaphoid associated with a distal radial epiphysiolysis. Clinical evaluation demonstrated decreased range of motion of the affected wrist and insidious pain on the snuffbox and tenderness on the distal radial physis. He was submitted to surgical treatment with scaphoid percutaneous fixation and radial styloid process in situ fixation. Clinical features improved, and he got back to competition 6 months after surgery without symptoms and with complete range of motion.

  13. Further application of the cleavage fracture stress model for estimating the T{sub 0} of highly embrittled ferritic steels

    Sreenivasan, P.R.


    The semi-empirical cleavage fracture stress model (CFS), based on the microscopic cleavage fracture stress, s{sub f}, for estimating the ASTM E1921 reference temperature (T{sub 0}) of ferritic steels from instrumented impact testing of unprecracked Charpy V-notch specimens is further confirmed by test results for additional steels, including steels highly embrittled by thermal aging or irradiation. In addition to the ferrite-pearlite, bainitic or tempered martensitic steels (which was examined earlier), acicular or polygonal ferrite, precipitation-strengthened or additional simulated heat affected zone steels are also evaluated. The upper limit for the applicability of the present CFS model seems to be T{sub 41J} ∝160 to 170 C or T{sub 0} or T{sub Qcfs} (T{sub 0} estimate from the present CFS model) ∝100 to 120 C. This is not a clear-cut boundary, but indicative of an area of caution where generation and evaluation of further data are required. However, the present work demonstrates the applicability of the present CFS model even to substantially embrittled steels. The earlier doubts expressed about T{sub Qcfs} becoming unduly non-conservative for highly embrittled steels has not been fully substantiated and partly arises from the necessity of modifications in the T{sub 0} evaluation itself at high degrees of embrittlement suggested in the literature.

  14. Numerical Investigation of Influence of In-Situ Stress Ratio, Injection Rate and Fluid Viscosity on Hydraulic Fracture Propagation Using a Distinct Element Approach

    Bo Zhang


    Full Text Available Numerical simulation is very useful for understanding the hydraulic fracturing mechanism. In this paper, we simulate the hydraulic fracturing using the distinct element approach, to investigate the effect of some critical parameters on hydraulic fracturing characteristics. The breakdown pressure obtained by the distinct element approach is consistent with the analytical solution. This indicates that the distinct element approach is feasible on modeling the hydraulic fracturing. We independently examine the influence of in-situ stress ratio, injection rate and fluid viscosity on hydraulic fracturing. We further emphasize the relationship between these three factors and their contributions to the hydraulic fracturing. With the increase of stress ratio, the fracture aperture increases almost linearly; with the increase of injection rate and fluid viscosity, the fracture aperture and breakdown pressure increase obviously. A low value of product of injection rate and fluid viscosity (i.e., Qμ will lead to narrow fracture aperture, low breakdown pressure, and complex or dispersional hydraulic fractures. A high value of Qμ would lead wide fracture aperture, high breakdown pressure, and simple hydraulic fractures (e.g., straight or wing shape. With low viscosity fluid, the hydraulic fracture geometry is not sensitive to stress ratio, and thus becomes a complex fracture network.

  15. Fracture Behavior under Impact.


    discussed for the different loading rates ob- tai ned . 1. Introduction In static fracture mechanics crack tip stress intensity factors can easi- - ly...deviation to the left or to the right hand side of the original crack path was observed. Herrmann [151 speculated that this behavior results from stress...Materials’ Draft 2c, American Society for Testing and Materials, Philadelphia, .. ,-- 1980. 15. Herrmann , G., "Dynamic Fracture of Beams in Bending

  16. Fractures in anisotropic media

    Shao, Siyi

    theory and experimental results in this report demonstrate that the presence of fractures in anisotropic material can be unambiguously interpreted if experimental measurements are made as a function of stress, which eliminates many fracture-generated discrete modes (e.g., interface waves, and leaky guided-modes). Orthogonal fracture networks that are often encountered in field exploration bring in additional challenges for seismic/acoustic data interpretation. An innovative wavefront imaging system with a bi-axial load frame was designed and implemented on orthogonally-fractured samples to determine the effect of fracture networks on elastic wave propagation. The effects of central wave guiding and extra time delays along a fracture intersection were observed in experiments and was analyzed. Interpreting data from media with intersecting fracture sets must account for fracture intersections and the non-uniformity of fracture properties caused by local tectonic conditions or other physical process such as non-uniform fluid distributions within a network and/or chemical alterations.

  17. Rib stress fractures among rowers: a systematic review on return to sports, risk factors and prevention.

    D'Ailly, Philip N; Sluiter, Judith K; Kuijer, Paul P


    Rib stress fractures (RSFs) are injuries frequently sustained by elite rowers with an injury rate of 8-16% over the course of a rowing career, resulting in negative effects on training and performance. For clinical management, the aim of this review was to describe time to return to sports, summarize potentially preventive measures and appraise the evidence on risk factors. A search strategy was performed in PubMed, SportDiscus, Web of Science and Embase till June 1st 2015. All studies were graded on their quality. The search resulted in 124 studies, of which 17 were included: Ten reported on return to sports, 17 reported on risk factors and nine on preventive measures. For return to sports, nine studies mentioned a loss of training of 4-6 weeks. The shortest period was one week and the longest 16 weeks. For risk factors, insufficient or conflicting evidence was found for changes in the training program, incorrect rowing technique, female gender, low bone mineral density, inadequate equipment, and training type. For prevention, gradual changes in the training program, alertness on the part of coaches and clinicians, and supplementation of diet and hormones are suggested as effective measures. However, no effect studies have been found. The main outcome of this review on RSFs is that little evidence is available on return to sports, risk factors and preventive measures. Coaches and clinicians should carefully guide and assist rowers suffering from RSFs in off training and in the subsequent training period to regain their pre-injury level.

  18. Long-term results and complications after treatment of bilateral fractures of the mandibular condyle

    Forouzanfar, T.; Lobbezoo, F.; Overgaauw, M.; de Groot, A.; Kommers, S.; van Selms, M.; van den Bergh, B.


    The purpose of this study was to investigate the long-term results of conservative treatment of bilateral condylar fractures and to study the influence of possible functional impairment on intensity of pain and associated disability. We studied 71 patients (mean (SD) age 33 (14) years) with conserva

  19. Red Flags Are Missed in the Prevention of Hip Fractures: Baseline Results of the Zurich Hip Fracture Trial

    From January 2005 to December 2007, we recruited 173 patients age 65 and older with acute hip fracture and a Folstein mini mental score of at least 15 into an ongoing double-blind RCT with vitamin D. 69% of hip fracture patients were admitted from home and 31% from institutions, 79% were women. Mean...

  20. Elastic stress transmission and transformation (ESTT) by confined liquid: A new mechanics for fracture in elastic lithosphere of the earth

    Xu, Xing-Wang; Peters, Stephen; Liang, Guang-He; Zhang, Bao-Lin


    We report on a new mechanical principle, which suggests that a confined liquid in the elastic lithosphere has the potential to transmit a maximum applied compressive stress. This stress can be transmitted to the internal contacts between rock and liquid and would then be transformed into a normal compressive stress with tangential tensile stress components. During this process, both effective compressive normal stress and tensile tangential stresses arise along the liquid–rock contact. The minimum effective tensile tangential stress causes the surrounding rock to rupture. Liquid-driven fracture initiates at the point along the rock–liquid boundary where the maximum compressive stress is applied and propagates along a plane that is perpendicular to the minimum effective tensile tangential stress and also is perpendicular to the minimum principal stress.

  1. Stress-wave induced fracture of unidirectional composites: an experimental study using digital image correlation method

    Lee, Dongyeon; Tippur, Hareesh V.


    In this work, fracture behavior of unidirectional graphite/epoxy composite materials is optically investigated. Single-edge notched coupons are studied under geometrically symmetric impact loading. The notch orientation parallel to or at an angle relative to the fiber orientation is considered to produce mode-I as well as mixed-mode fracture. Stress-wave induced crack initiation and rapid crack growth events are studied using a digital correlation technique and high-speed photography. Surface deformations histories in the crack-tip vicinity are obtained by analyzing decorated speckle recordings. Measured deformation fields are used to extract fracture parameters and examine the effect of fiber orientation on crack initiation and growth behaviors. The maximum crack speed observed is the highest for mode-I dominant conditions and decreases with increasing fiber orientation angle. With increasing fiber orientation angle, crack takes longer to attain the maximum speed upon initiation. The crack initiation toughness values decrease with increasing degree-of-anisotropy.

  2. Measurement of Residual Stress in a Welded Branch Connection and Effects on Fracture Behaviour

    Law, M.; Luzin, V.; Kirstein, O.


    The branch analysed in this paper was not post weld heat treated, resulting in significant residual stresses. Assessment codes assume these to be at, or close to, yield. An integrity assessment of a welded branch connection was carried out using these high assumed residual stresses. The weld then had residual stresses determined by neutron diffraction, performed using ANSTO's residual stress diffractometer, Kowari. The maximum measured residual stress (290 MPa or 60% of yield) was much lower than the yield value assumed by assessment codes. Reanalysing with the actual residual stresses almost doubled the critical crack size, increasing the safety of the connection.


    Arun Kumar


    Full Text Available BACKGROUND Among the various methods of treating the long bone fractures in children less than 5yrs (POP cast and adolescents 16yrs (IMN, flexible intramedullary nail has gained importance because of its stability, not violating the physis and less complications and early rehabilitation. Irrespective of mode of treatment, goal shall be to achieve union at fracture site, control length and alignment, minimize the morbidity and complications for patient and their family. MATERIALS AND METHODS A prospective study was conducted on children of both sexes, between the age group of 5-15yrs with diaphyseal fractures of long bones, meeting the inclusion and exclusion criteria during the study period at RRMCH (September 2012 to September 2014. Totally, 30 cases were evaluated clinically and radiologically and followed up at 3, 6, 12, 24 weeks after surgery. Final outcome was assessed using Flynn’s criteria for Tens Scoring System. RESULTS Results of entire, 30 patients were followed up for an average of 6 months, was excellent in 19(63% cases and satisfactory in 11(37% cases and no poor outcome. CONCLUSION Based on this study and result, we found that intramedullary elastic nailing technique is an ideal method for treatment of pediatric femoral and tibial diaphyseal fractures.

  4. A geometrically based method for predicting stress-induced fracture aperture and flow in discrete fracture networks

    Bisdom, Kevin; Bertotti, Giovanni; Nick, Hamid


    on subsurface fracture aperture, which is essential for quantifying porosity and permeability. Apertures are difficult to obtain from either outcropping or subsurface data and are therefore often based on fracture size or scaling relationships, but these do not consider the orientation and spatial distribution...

  5. Radiographic factors and effect of fifth metatarsal Jones and diaphyseal stress fractures on participation in the NFL.

    Carreira, Dominic S; Sandilands, Scott M


    Jones fracture and proximal diaphyseal stress fracture of the fifth metatarsal have been associated with prolonged healing times and nonunions. We hypothesized that the Jones fracture and proximal diaphyseal stress fracture have a high incidence in elite collegiate football players and that they lead to a decrease in participation in the NFL. Also, we hypothesized that these fractures are associated with a cavovarus foot alignment. The database collected by a single NFL team during the 2004 to 2009 NFL Combines was reviewed to identify players with Jones and proximal diaphyseal fifth metatarsal fractures. A total of 74 fifth metatarsal fractures were identified in 68 players. Subsequent participation data also were collected through the website and included games played and years played. Digital plain radiographs and additional imaging studies also were reviewed to determine the extent of healing, types of fixation utilized, and foot alignment. The locations of fractures in the proximal fifth metatarsal were 45 (61%) in the Jones area, 15 (20%) in the proximal diaphyseal area, and 14 (19%) of indeterminate location. The number of patients treated with intramedullary fixation was 55/74 (74%). Of 74 proximal fifth metatarsal fractures, 9 (12.2%) were nonunions at the time of the NFL Combine medical examinations. With the numbers available, the average number of games played in the NFL was not significantly different in the fifth metatarsal fracture group, 16.9, compared to the control group, 24.9 (P > .05). The average number of games started was 7.4 in the fracture group versus 12.1 in the control group (P > .05). No significant differences were noted in the number of years played in the NFL. Except for talonavicular angle measurements, all measurements of coronal plane alignment demonstrated significant differences across groups, but no differences were noted in sagittal plane alignment. No statistically significant difference was noted in participation in


    Bharath Kumar


    Full Text Available BACKGROUND : Pertrochanteric fractures forms a major share of proximal femoral fractures in young and old . Proper implant selection and surgical planning plays a pivotal role in providing fracture union and early rehabilitation of patients to prevent complications due to recumbency . AIM : The aim of this retrospective study is to assess the results of proximal femoral nails in unstable pertrochanteric f ractures . MATERIALS AND METHODS : This study was performed in the Department of Orthopaedic Surgery , Chettinad hospital and research institute , Kelambakkam between November 2012 and December 2014 . 15 patients with pertrochanteric fractures were retrospectively followed . Among the fifteen 9 were male and 6 were female with an average age of 43 . Eleven patients sustained Intertrochanteric fractures , 8 of A2 type and 3 of A3 type according to AO classification . 4 patients had subtroch anteric fractures of seinseimer Type 5 . RESULTS : Short PFN was used in all the 11 Intertrochanteric fractures and long PFN was used in the 4 subtrochanteric fractures . All fractures healed by around 3 . 5 months . There is one case of varus malunion and one c ase of screw pullout which required implant removal . The limitations of this study are its retrospective nature , small sample size and short follow up . CONCLUSION : Our results show that proximal femoral nails being load sharing implants form an ideal choic e for stabil ising pertrochanteric fractures . Minimally invasive technique of insertion with less blood loss make it an ideal choice in such complex scenarios .

  7. Video analysis of the biomechanics of a bicycle accident resulting in significant facial fractures.

    Syed, Shameer H; Willing, Ryan; Jenkyn, Thomas R; Yazdani, Arjang


    This study aimed to use video analysis techniques to determine the velocity, impact force, angle of impact, and impulse to fracture involved in a video-recorded bicycle accident resulting in facial fractures. Computed tomographic images of the resulting facial injury are presented for correlation with data and calculations. To our knowledge, such an analysis of an actual recorded trauma has not been reported in the literature. A video recording of the accident was split into frames and analyzed using an image editing program. Measurements of velocity and angle of impact were obtained from this analysis, and the force of impact and impulse were calculated using the inverse dynamic method with connected rigid body segments. These results were then correlated with the actual fracture pattern found on computed tomographic imaging of the subject's face. There was an impact velocity of 6.25 m/s, impact angles of 14 and 6.3 degrees of neck extension and axial rotation, respectively, an impact force of 1910.4 N, and an impulse to fracture of 47.8 Ns. These physical parameters resulted in clinically significant bilateral mid-facial Le Fort II and III pattern fractures. These data confer further understanding of the biomechanics of bicycle-related accidents by correlating an actual clinical outcome with the kinematic and dynamic parameters involved in the accident itself and yielding a concrete evidence of the velocity, force, and impulse necessary to cause clinically significant facial trauma. These findings can aid in the design of protective equipment for bicycle riders to help avoid this type of injury.

  8. Post-mortem imaging of laryngohyoid fractures in strangulation incidents: first results.

    Kempter, M; Ross, S; Spendlove, D; Flach, P M; Preiss, U; Thali, M J; Bolliger, S A


    Fractures and soft-tissue injuries of the neck are of great importance in forensic pathology, as they help in assessing whether strangulation took place, and if so, how severely. In this study, we examined the usefulness of post-mortem imaging with multislice computed tomography (MSCT) in detecting lesions of the laryngohyoid structures and the surrounding soft-tissues. For this purpose, we examined MSCT images of the neck of eight deceased persons who had suffered different types of strangulation and compared the findings with those obtained at the subsequent forensic autopsy. In six of the eight cases (75%), the fracture findings at autopsy were concordant with those found with MSCT. In the two non-congruent cases, MSCT revealed fractures, which were not discovered at autopsy. Soft-tissue haemorrhages were detected by autopsy in five cases, but only in one case with MSCT. MSCT does not suffice in detecting soft-tissue injuries. These preliminary results are promising regarding the detection of fractures in strangulation cases. If these results can be confirmed in larger studies, we believe that post-mortem MSCT may serve - in combination with a thorough external examination and a profound incident-scene investigation - as a useful decision-making tool regarding the necessity of further examinations, i.e. autopsy.

  9. Pressure Transient Analysis and Flux Distribution for Multistage Fractured Horizontal Wells in Triple-Porosity Reservoir Media with Consideration of Stress-Sensitivity Effect

    Jingjing Guo


    Full Text Available Triple-porosity model is usually adopted to describe reservoirs with multiscaled pore spaces, including matrix pores, natural fractures, and vugs. Multiple fractures created by hydraulic fracturing can effectively improve the connectivity between existing natural fractures and thus increase well deliverability. However, little work has been done on pressure transient behavior of multistage fractured horizontal wells in triple-porosity reservoirs. Based on source/sink function method, this paper presents a triple-porosity model to investigate the transient pressure dynamics and flux distribution for multistage fractured horizontal wells in fractured-vuggy reservoirs with consideration of stress-dependent natural fracture permeability. The model is semianalytically solved by discretizing hydraulic fractures and Pedrosa’s transformation, perturbation theory, and integration transformation method. Type curves of transient pressure dynamics are generated, and flux distribution among hydraulic fractures for a fractured horizontal well with constant production rate is also discussed. Parametric study shows that major influential parameters on transient pressure responses are parameters pertinent to reservoir properties, interporosity mass transfer, and hydraulic fractures. Analysis of flux distribution indicates that flux density gradually increases from the horizontal wellbore to fracture tips, and the flux contribution of outermost fractures is higher than that of inner fractures. The model can also be extended to optimize hydraulic fracture parameters.

  10. Arthroscopic debridement of the elbow for arthrofibrosis resulting from nondisplaced fracture of the radial head.

    Lapner, Peter C; Leith, Jordan M; Regan, William D


    Mason type I fractures of the radial head consist of fractures that occur without displacement. Arthrofibrosis is a rarely reported complication of Mason I radial head fractures. Symptoms include pain, stiffness, and crepitus. We assessed the efficacy of an arthroscopic procedure including debridement and capsular release for patients with persistent symptoms and failure of nonoperative therapy. Therapeutic study, case series. Retrospective analysis of functional outcome data was carried out for all eligible cases treated at our institution between 1995 and 2003. Twenty procedures were performed, with 8 patients lost to follow-up. The outcome data consisted of range of motion measurements and functional indices derived from the Mayo Performance Index (MPI). Mean follow-up duration was 54 months. Surgical findings included extensive scarring in the radiocapitellar joint, cartilage loss in the radial head and capitellum, scarring and synovitis in the ulnohumeral joint, and scarring with adhesions in the posterior compartment and posterolateral gutter. The mean MPI score preoperatively was 64.1 and the mean postoperative score was 89.5. Total range of motion arc rose from 108 degrees preoperatively to 126 degrees postoperatively. The outcome data suggest that arthroscopic debridement and capsular release is an effective method of treating arthrofibrosis resulting from Mason I radial head fractures. Level IV.

  11. Local Inflammation in Fracture Hematoma: Results from a Combined Trauma Model in Pigs

    K. Horst


    Full Text Available Background. Previous studies showed significant interaction between the local and systemic inflammatory response after severe trauma in small animal models. The purpose of this study was to establish a new combined trauma model in pigs to investigate fracture-associated local inflammation and gain information about the early inflammatory stages after polytrauma. Material and Methods. Combined trauma consisted of tibial fracture, lung contusion, liver laceration, and controlled hemorrhage. Animals were mechanically ventilated and under ICU-monitoring for 48 h. Blood and fracture hematoma samples were collected during the time course of the study. Local and systemic levels of serum cytokines and diverse alarmins were measured by ELISA kit. Results. A statistical significant difference in the systemic serum values of IL-6 and HMGB1 was observed when compared to the sham. Moreover, there was a statistical significant difference in the serum values of the fracture hematoma of IL-6, IL-8, IL-10, and HMGB1 when compared to the systemic inflammatory response. However a decrease of local proinflammatory concentrations was observed while anti-inflammatory mediators increased. Conclusion. Our data showed a time-dependent activation of the local and systemic inflammatory response. Indeed it is the first study focusing on the local and systemic inflammatory response to multiple-trauma in a large animal model.

  12. New development of hydraulic fracturing technique for in-situ stress measurement at great depth of mines


    In-situ stress measurement using the hydraulic fracturing technique was made at Wanfu Coal Mine in Shandong Province,China.To solve problems caused by great measuring depth and extra thick overburden soil layers in the mine,a series of improved techniques were developed for the traditional hydraulic fracturing technique and equipment to increase their pressure-enduring ability and to ensure safe and flexible removal of the sealing packers with other experimental apparatus.Successful in-situ stress measurement at 37 points within 7 boreholes,which were mostly over 1000 m deep,was completed.Through the measurement,detailed in

  13. A comparison of the stress corrosion cracking susceptibility of commercially pure titanium grade 4 in Ringer's solution and in distilled water: a fracture mechanics approach.

    Roach, Michael D; Williamson, R Scott; Thomas, Joseph A; Griggs, Jason A; Zardiackas, Lyle D


    From the results of laboratory investigations reported in the literature, it has been suggested that stress corrosion cracking (SCC) mechanisms may contribute to early failures in titanium alloys that have elevated oxygen concentrations. However, the susceptibility of titanium alloys to SCC in physiological environments remains unclear. In this study, a fracture mechanics approach was used to examine the SCC susceptibility of CP titanium grade 4 in Ringer's solution and distilled de-ionized (DI) water, at 37°C. The study duration was 26 weeks, simulating the non-union declaration of a plated fracture. Four wedge loads were used corresponding to 86-95% of the alloy's ligament yield load. The longest cracks were measured to be 0.18 mm and 0.10 mm in Ringer's solution and DI water, respectively. SEM analysis revealed no evidence of extensive fluting and quasi-cleavage fracture features which, in literature reports, were attributed to SCC. We thus postulate that the Ringer's solution accelerated the wedge-loaded crack growth without producing the critical stresses needed to change the fracture mechanism. Regression analysis of the crack length results led to a significant best-fit relationship between crack growth velocity (independent variable) and test electrolyte, initial wedge load, and time of immersion of specimen in electrolyte (dependent variables).




    Full Text Available Ground water is considered to be the best safe protected drinking water source and bore wells are drilled in hard crystalline rock terrains for drinking water, irrigation and industrial purposes. Even after scientific location, some bore wells yield inadequate quantity of water or fail to yield. The success of bore wells depend largely onnumber, length, dilation and interconnectivity of fractures encountered on drilling. Considering the cost factor involved in drilling a new bore well, rejuvenation of failed bore well through some technique is thought off. The innovative technology of ‘hydro fracturing’ is a new interdisciplinary approach of Hydro mechanical tostimulate the bore well to improve the yield by applying water pressure into bore well by using a heavy duty mechanical compressor. The hydro fracturing technique was first used in oil well to increase oil and gas production. In this research paper, the hydraulic pressure applied increases with depth reflecting the rigidness,toughness of rock. The fracture development, propagation of fracture and stress behavior depends on the physical and mechanical properties of rocks. The hydro fracturing process has been conducted in three depth zones ranging from 8 m to 45 m below ground level in Annavasal union of Pudukottai district, Tamil Nadu, India. The Pressure application varies depending on the geological formations. This study pertains to a part of research work. The minimum and maximum pressures applied are 1 and 10 N/mm2 respectively. The maximumpressure of 10 N/mm2 has been recorded in the third zone, where the country rock is charnockite which is generally massive, compact and dense rock. Generally for the igneous rock in the third zone in the depth range of 40 to 50 m, more than 7 N/mm2 of pressure has been applied indicating extremely strong nature with uniaxial compressive strength 100 – 300 N/mm2, tensile strength 7- 25 N/mm2. Out of 37 bore wells 32.4% of bore wells have shown

  15. Soil compaction: Evaluation of stress transmission and resulting soil structure

    Naveed, Muhammad; Schjønning, Per; Keller, Thomas;

    and compaction-resulted soil structure at the same time. Stress transmission was quantified using both X-ray CT and Tactilus sensor mat, and soil-pore structure was quantified using X-ray CT. Our results imply that stress transmission through soil highly depends on the magnitude of applied load and aggregate......, as a result stress transmission mode was shifted from discrete towards more like a continuum. Continuum-like stress transmission mode was better simulated with Boussinesq (1885) model based on theory of elasticity compared to discrete. The soil-pore structure was greatly affected by increasing applied......Accurate estimation of stress transmission and resultant deformation in soil profiles is a prerequisite for the development of predictive models and decision support tools for preventing soil compaction. Numerous studies have been carried out on the effects of soil compaction, whilst relatively few...

  16. A retrospective cohort study on the influence of UV index and race/ethnicity on risk of stress and lower limb fractures

    Montain, Scott J; McGraw, Susan M.; Ely, Matthew R.; Grier, Tyson L; Knapik, Joseph J.


    Background Low vitamin D status increases the risk of stress fractures. As ultraviolet (UV) light is required for vitamin D synthesis, low UV light availability is thought to increase the risk of vitamin D insufficiency and poor bone health. The purpose of this investigation was to determine if individuals with low UV intensity at their home of record (HOR) or those with darker complexions are at increased risk of developing stress fractures and lower limb fractures during U.S. Army Basic Com...

  17. Results of Closed Intramedullary Nailing using Talwarkar Square Nail in Adult Forearm Fractures

    Nadeem A Lil


    Full Text Available The aim of the study was to evaluate results of closed intramedullary nailing using Talwarkar square nails in adult forearm fractures. We prospectively evaluated 34 patients with both bone forearm fractures. The average time to union was 12.8 (SD +3.2 weeks with cast support for a mean of 8.2 weeks. Union was achieved in 31 out of 34 patients. Using the Grace and Eversmann rating system, 17 patients were excellent, 10 were good, and 4 had an acceptable result. Three patients had non-unions, 2 for the radius and one for the ulna. There were two cases of superficial infection, one subject had olecranon bursitis, and one case of radio-ulnar synostosis. Complication rates associated with the use of square nails were lower compared to plate osteosynthesis and locked intramedullary nails. To control rotation post- operatively, there is a need for application of an above-elbow cast after nailing.

  18. Results of ASTM round robin testing for mode 1 interlaminar fracture toughness of composite materials

    Obrien, T. Kevin; Martin, Roderick H.


    The results are summarized of several interlaboratory 'round robin' test programs for measuring the mode 1 interlaminar fracture toughness of advanced fiber reinforced composite materials. Double Cantilever Beam (DCB) tests were conducted by participants in ASTM committee D30 on High Modulus Fibers and their Composites and by representatives of the European Group on Fracture (EGF) and the Japanese Industrial Standards Group (JIS). DCB tests were performed on three AS4 carbon fiber reinforced composite materials: AS4/3501-6 with a brittle epoxy matrix; AS4/BP907 with a tough epoxy matrix; and AS4/PEEK with a tough thermoplastic matrix. Difficulties encountered in manufacturing panels, as well as conducting the tests are discussed. Critical issues that developed during the course of the testing are highlighted. Results of the round robin testing used to determine the precision of the ASTM DCB test standard are summarized.

  19. Results of cemented bipolar hemiarthroplasty for fracture of the femoral neck - 10 year study

    Maini P


    Full Text Available Background : One of the most common treatments of displaced fracture of femoral neck in elderly is bipolar hemiarthroplasty. Method : Two hundred and seventy patients of displaced fracture of femoral neck were treated by bipolar hemiarthroplasty. The Mean age of the patients at the time of surgery was 69.80 years. Results : Follow up ranged between 12 months and 120 months. There were 8 cases each of acetabular erosion and protrusion with 10 cases of femoral stem loosening. Eight cases had post operative dislocation requiring open reduction. Eighteen patients got revision surgery to total hip replacement. The overall incidence of DVT/PE was 9.9% which declined after regular use of low molecular weight heparin. Eleven patients had post operative infection. There were 54.2 % excellent results, 21.0 % good results, 10.7 % fair and 3.7% poor results. Conclusion : Elderly patients with displaced fracture of neck femur are able to ambulate early after Cemented bipolar hemi arthroplasty. The complication rate is low, the component survival long and pre injury functional status is restored in majority of patients.

  20. The concept of the average stress in the fracture process zone for the search of the crack path

    Yu.G. Matvienko


    Full Text Available The concept of the average stress has been employed to propose the maximum average tangential stress (MATS criterion for predicting the direction of fracture angle. This criterion states that a crack grows when the maximum average tangential stress in the fracture process zone ahead of the crack tip reaches its critical value and the crack growth direction coincides with the direction of the maximum average tangential stress along a constant radius around the crack tip. The tangential stress is described by the singular and nonsingular (T-stress terms in the Williams series solution. To demonstrate the validity of the proposed MATS criterion, this criterion is directly applied to experiments reported in the literature for the mixed mode I/II crack growth behavior of Guiting limestone. The predicted directions of fracture angle are consistent with the experimental data. The concept of the average stress has been also employed to predict the surface crack path under rolling-sliding contact loading. The proposed model considers the size and orientation of the initial crack, normal and tangential loading due to rolling–sliding contact as well as the influence of fluid trapped inside the crack by a hydraulic pressure mechanism. The MATS criterion is directly applied to equivalent contact model for surface crack growth on a gear tooth flank.

  1. Humeral shaft fractures: Retrospective results of non-operative and operative treatment of 186 patients

    K.C. Mahabier (Kiran); L.M.M. Vogels (Lucas); B.J. Punt (Bas); G.R. Roukema (Gert); P. Patka (Peter); E.M.M. van Lieshout (Esther)


    textabstractBackground: Humeral shaft fractures account for 1-3% of all fractures and 20% of the fractures involving the humerus. The aim of the current study was to compare the outcome after operative and non-operative treatment of humeral shaft fractures, by comparing the time to radiological unio

  2. Proximal femoral fracture in a man resulting from modern clipless pedals: a case report

    Patel Neil


    Full Text Available Abstract Introduction The use of clipless pedals amongst recreational cyclists has become increasingly popular in recent years. We describe a hip fracture, that was sustained due to inadequate set up of such pedals. To the best of our knowledge, this has only been described once before, and this was in the non-English language medical literature. Case Report A 38-year-old Caucasian man who was a club cyclist sustained a displaced intracapsular fracture of the hip whilst cycling. As a direct result of the incorrect set-up of his clipless pedals he was unable to release his feet whilst slowing to a halt. This resulted in a loss of balance and subsequent fall with a direct impact onto his left hip. The resulting fracture was managed successfully with early closed reduction and fixation. At six month review he was walking unaided without pain but, as yet, has been unable to return to cycling. Conclusion This case highlights the dangers of clipless pedals even in experienced cyclists, and underlines the importance of proper information for their correct setup to minimise the risk of potentially serious injuries, especially in the region of the hip.

  3. [Results after internal fixation of humerus distal fractures in patients over than 65 years old].

    Serrano-Mateo, L; Lopiz, Y; León-Serrano, C; García-Fernández, C; López-Durán-Stern, L; Marco, F


    Distal humerus fractures in the elderly frequently associated with poor bone quality and comminution, making it harder to achieve proper osteosynthesis. Our aim is to evaluate the radiological and functional results of open reduction and internal fixation of these fractures. Retrospective study of 26 patients treated by open reduction and internal fixation between the years 2005-2010. Mean follow-up was 42 months. At final follow-up, a radiography evaluation (Knirk and Jupiter score) and clinical examination using Mayo Elbow Performance Score and Quick-Disabilities of the Arm, Shoulder and Hand Score was performed. Mean age of the group was 76.8 years (65-89), with 83% of the patients being female. Sixteen patients suffered type C fractures and 8 type A by AO classification. All underwent posterior surgical approach. Mean elbow flexion reached 118.86°, with a mean extension deficit of 25°. More than 3-quarters (79.1%) of the patients showed 0-1 grade degenerative changes on the X-ray films at final follow-up. Functional results reached an average 19.87 points on Quick-Disabilities of the Arm, Shoulder and Hand Score, and 85 points on Mayo Elbow Performance Score scores. Non-union occurred in 2 cases: distal humerus in one patient and olecranon osteotomy in another. Ulnar nerve neuropraxia was recorded in 2 cases, and radial nerve in one. All 3 recovered uneventfully. Revision surgery was required, with 2 patients needing hardware removal and one a new fixation. Treatment by open reduction and internal fixation with plating in elderly people for type A and C distal humerus fractures gives good functional results regarding this population, and thus scarcely disturbs their quality of life. Copyright © 2012 SECOT. Published by Elsevier Espana. All rights reserved.

  4. Fault interaction and stresses along broad oceanic transform zone: Tjörnes Fracture Zone, north Iceland

    Homberg, C.; Bergerat, F.; Angelier, J.; Garcia, S.


    Transform motion along oceanic transforms generally occurs along narrow faults zones. Another class of oceanic transforms exists where the plate boundary is quite large (˜100 km) and includes several subparallel faults. Using a 2-D numerical modeling, we simulate the slip distribution and the crustal stress field geometry within such broad oceanic transforms (BOTs). We examine the possible configurations and evolution of such BOTs, where the plate boundary includes one, two, or three faults. Our experiments show that at any time during the development of the plate boundary, the plate motion is not distributed along each of the plate boundary faults but mainly occurs along a single master fault. The finite width of a BOT results from slip transfer through time with locking of early faults, not from a permanent distribution of deformation over a wide area. Because of fault interaction, the stress field geometry within the BOTs is more complex than that along classical oceanic transforms and includes stress deflections close to but also away from the major faults. Application of this modeling to the 100 km wide Tjörnes Fracture Zone (TFZ) in North Iceland, a major BOT of the Mid-Atlantic Ridge that includes three main faults, suggests that the Dalvik Fault and the Husavik-Flatey Fault developed first, the Grismsey Fault being the latest active structure. Since initiation of the TFZ, the Husavik-Flatey Fault accommodated most of the plate motion and probably persists until now as the main plate structure.

  5. Surgical treatment of bilateral femoral stress fractures related with long-term alendronate therapy.

    Kanatlı, Ulunay; Ataoğlu, M Baybars; Özer, Mustafa; Topçu, H Nevzat; Çetinkaya, Mehmet


    A 67-year-old female patient admitted to our outpatient clinic suffering from pain in both thighs for one year without any history of trauma. Patient was receiving alendronate therapy for five years. Physical examination revealed pain increasing with weight-bearing in both thighs with full range of hip and knee movements. Radiographs showed an area of thickened cortex of middle femoral diaphysis in both femurs, but no fracture. Bone scan showed a single area of increased uptake of radioisotope. These images were compatible with stress fractures of both femurs. Dual-energy X-ray absorptiometry revealed a T-score of -3.2 for the lumbar spine and -3.5 for the hip. Alendronate treatment was ceased. Calcium and vitamin D treatment were started. Patient was performed prophylactic surgical stabilization by titanium elastic nails in May 2009. On first day after the surgery, unsupported mobilization and weight-bearing activities were started. Upon persistence of pain on left thigh, plate fixation was performed for the nonunion in June 2012. Patient is now pain-free and able to walk with full weight-bearing without any complications.

  6. Stress Concentration and Fracture at Inter-variant Boundaries in an Al-Li Alloy

    Crooks, Roy; Tayon, Wes; Domack, Marcia; Wagner, John; Beaudoin, Armand


    Delamination fracture has limited the use of lightweight Al-Li alloys. Studies of secondary, delamination cracks in alloy 2090, L-T fracture toughness samples showed grain boundary failure between variants of the brass texture component. Although the adjacent texture variants, designated B(sub s1) and B(sub s2), behave similarly during rolling, their plastic responses to mechanical tests can be quite different. EBSD data from through-thickness scans were used to generate Taylor factor maps. When a combined boundary normal and shear tensor was used in the calculation, the delaminating grains showed the greatest Taylor Factor differences of any grain pairs. Kernel Average Misorientation (KAM) maps also showed damage accumulation on one side of the interface. Both of these are consistent with poor slip accommodation from a crystallographically softer grain to a harder one. Transmission electron microscopy was used to confirm the EBSD observations and to show the role of slip bands in the development of large, interfacial stress concentrations. A viewgraph presentation accompanies the provided abstract.

  7. Influence of early postoperative complication on the operative results in elderly intertrochanteric fractured patients


    Objective:Early complications were analyzed in those with Evans Ⅲ type of intertrochanteric fracture treated with operation or nonoperative approaches. Methods:59 cases with Evans Ⅲ type of intertrochanteric fracture between June, 1999 to July, 2006 were admitted in our department. 38 patients were complicated with cardiovascular diseases, such as hypertension and arrhythmia. All the cases were operated. Results:58 cases were operated successfully. One died of pulmonary interstitial fibrosis. Grade data of different age brackets indicated that early infective complications had apparent differences between the operation and the control group. Compared with the control group, the operation group had benefits such as fewer complications, especially the infective complications, and incidence of lower extremities venous thrombosis, and the results showed notable differences. Conclusion:In elderly patients with Evans Ⅲ type of intertrochanteric fracture, the incidence of pulmonary infection was the highest. Venous thrombosis in lower extremities was the most serious complication. So it will be helpful to perform the quadriceps femories function exercise. The postoperative effect is also related with the operation approach.


    Prasanta Kr.


    Full Text Available ABSTRACT: INTRODUCTION: Osteosynthesis with open reduction technique in comm inuted fracture has several disadvantages like increase ra te of non-union, soft tissue problem, infection and implant failure. These problems may be overcome b y percutaneous bridge plating technique which preserve the vascularity and soft ti ssue attachment of fracture fragments. MATERIALS AND METHODS: Twenty-five patients were involve in this study . Al l of twenty- five patients with closed comminuted diaphyseal fract ures of femur (n-10 and tibia (n-15 were operated on using the principle indirect reductio n and biological fixation with bridge plate under image intensifier. Partial and full weight be aring were allowed according to clinical and radiological union. RESULTS: Most regained excellent range of motion of knee and ankle. Mean time of radiological union was 20.12 weeks. Two pati ents had superficial skin problem which healed with local wound care. One patient had non un ion which was healed by bone grafting. In this study excellent result was seen in 18 cases, g ood in five and fair in two patients. CONCLUSION: Our study indicates that minimally invasive bridge plating is an effective alternative for treatment of comminuted diaphyseal f racture of long bones. These complex fractures give complete recovery of normal limb func tion at an ear ly stage with less complication.

  9. Mid term results of Furlong LOL uncemented hip hemiarthroplasty for fractures of the femoral neck.

    Chandran, Prakash; Azzabi, Mohammed; Burton, Dave J C; Andrews, Mark; Bradley, John G


    We report the mid-term results of hemiarthroplasty with the Furlong hydroxyapatite coated bipolar prosthesis for displaced (Garden type III and IV) intracapsular hip fracture in 480 patients operated between 1989 and 2000. Three hundred sixty eight (77%) patients were lost to follow-up due to death, dementia or movement away from the area. In the patients followed up there was an 8% reoperation rate for infection, aseptic loosening, periprosthetic fracture and acetabular erosion. One hundred and twelve patients with a mean follow-up of 4 years (3-14) were studied. Eighty eight percent had no or slight pain, 77% could mobilise outdoors and 89% needed either no aid or a single walking stick to mobilise. Radiographic assessment revealed a stable implant with visible osseointegration in 91%. We conclude that hemiarthroplasty with the hydroxyapatite coated bipolar Furlong LOL prosthesis for displaced intracapsular fracture of the neck of the femur gives good mid term results in elderly patients for return to mobility, use of mobility aids and freedom from pain. It avoids the need for cement and provides satisfactory incorporation into the host bone. The use of a modular head makes revision to total hip replacement easier.

  10. Extracorporeal shockwave therapy in the treatment of stress fracture of tibia. Report of a case

    Santiago Gómez García


    Full Text Available Pain in the lower limbs induced by exercise is common in military cadets due to long periods of jogging as part of his training and is related to overtraining. Stress fractures of tíbia are common among the disorders affecting them but most often are not diagnosed. The period of convalescence is prolonged sometimes leading to abandon their atividades. A case of an affected cadet to which treated by extracorporeal shockwave therapy showing reduced pain at rest and increased time trotting achieved without painful. Because of the importance that medical staff primarily Orthopaedic Surgeons and Sports Physicians and other health professionals involved in the care know about the existence of pathology as this new therapeutic alternative is that the case is presented.

  11. Exercise-induced rib stress fractures: potential risk factors related to thoracic muscle co-contraction and movement pattern

    Vinther-Knudsen, Archibald; Kanstrup, I-L; Christiansen, E


    The etiology of exercise-induced rib stress fractures (RSFs) in elite rowers is unclear. The purpose of the study was to investigate thoracic muscle activity, movement patterns and muscle strength in elite rowers. Electromyographic (EMG) and 2-D video analysis were performed during ergometer rowi...

  12. Investigating the Influence of Regional Stress on Fault and Fracture Permeability at Pahute Mesa, Nevada National Security Site

    Reeves, Donald M. [Desert Research Inst. (DRI), Reno, NV (United States); Smith, Kenneth D. [Univ. of Nevada, Reno, NV (United States); Parashar, Rishi [Desert Research Inst. (DRI), Reno, NV (United States); Collins, Cheryl [Desert Research Inst. (DRI), Las Vegas, NV (United States); Heintz, Kevin M. [Desert Research Inst. (DRI), Las Vegas, NV (United States)


    Regional stress may exert considerable control on the permeability and hydraulic function (i.e., barrier to and/or conduit for fluid flow) of faults and fractures at Pahute Mesa, Nevada National Security Site (NNSS). In-situ measurements of the stress field are sparse in this area, and short period earthquake focal mechanisms are used to delineate principal horizontal stress orientations. Stress field inversion solutions to earthquake focal mechanisms indicate that Pahute Mesa is located within a transtensional faulting regime, represented by oblique slip on steeply dipping normal fault structures, with maximum horizontal stress ranging from N29°E to N63°E and average of N42°E. Average horizontal stress directions are in general agreement with large diameter borehole breakouts from Pahute Mesa analyzed in this study and with stress measurements from other locations on the NNSS.

  13. Estimating the reactivation potential of existing fractures in subsurface granitoids from outcrop analogues and in-situ stress modeling: implications for EGS reservoir stimulation with an example from Meiningen (Thuringia, Central Germany)

    Ustaszewski, Kamil; Kasch, Norbert; Siegburg, Melanie; Navabpour, Payman; Thieme, Manuel


    The southwestern part of Thuringia (central Germany) hosts large subsurface extents of Lower Carboniferous granitoids of the Mid-German Crystalline Rise, overlain by an up to several kilometer thick succession of Lower Permian to Mid-Triassic volcanic and sedimentary rocks. The granitic basement represents a conductivity-controlled ('hot dry rock') reservoir of high potential that could be targeted for economic exploitation as an enhanced geothermal system (EGS) in the future. As a preparatory measure, the federal states of Thuringia and Saxony have jointly funded a collaborative research and development project ('Optiriss') aimed at mitigating non-productivity risks during the exploration of such reservoirs. In order to provide structural constraints on the fracture network design during reservoir stimulation, we have carried out a geometric and kinematic analysis of pre-existing fracture patterns in exposures of the Carboniferous basement and Mesozoic cover rocks within an area of c. 500 km2 around the towns of Meiningen and Suhl, where granitic basement and sedimentary cover are juxtaposed along the southern border fault of the Thuringian Forest basement high. The frequency distribution of fractures was assessed by combining outcrop-scale fracture measurements in 31 exposures and photogrammetric analysis of fractures using a LIDAR DEM with 5 m horizontal resolution and rectified aerial images at 4 localities. This analysis revealed a prevalence of NW-SE-trending fractures of mainly joints, extension veins, Permian magmatic dikes and subordinately brittle faults in the Carboniferous granitic basement, which probably resulted from Permian tectonics. In order to assess the reactivation potential of fractures in the reservoir during a stimulation phase, constraints on the current strain regime and in-situ stress magnitudes, including borehole data and earthquake focal mechanisms in a larger area, were needed. These data reveal a presently NW-SE-trending maximum

  14. Burst fracture of the thoracolumbar spine: correlation between kyphosis and clinical result of the treatment

    Rodrigo Arnold Tisot


    Full Text Available OBJECTIVE: To evaluate the correlation between kyphosis due to burst fractures of thoracic and lumbar spine and clinical outcome in patients undergoing conservative or surgical treatment.METHODS: A retrospective, cross-sectional study was conducted with 29 patients with thoracolumbar burst fractures treated by the Spine Group in a trauma reference hospital between the years 2002 and 2011. Patients were followed-up as outpatients for a minimum of 24 months. All cases were clinically evaluated by Oswestry and SF-36 quality of life questionnaires and the visual analogue scale (VAS of pain. They were also evaluated by X-ray examinations and CT scans of the lumbosacral spine at the time of hospitalization and subsequently as outpatients by Cobb method for measuring the degree of kyphosis.RESULTS: There was no statistically significant correlation between the degree of initial kyphosis and clinical outcome measured by VAS and by most of the SF-36 domains in both patients treated conservatively and the surgically treated. The Oswestry questionnaire showed benefits for patients who received conservative treatment (p=0.047 compared to those surgically treated (p=0.335. The analysis of difference between initial and final kyphosis and final kyphosis alone in relation to clinical outcome showed no statistical correlation in any of the scores used.CONCLUSION: The clinical outcome of treatment of the thoracic and lumbar burst fractures was not influenced by a greater or lesser degree of initial or residual kyphosis, regardless of the type of treatment.

  15. Bilateral rapidly destructive arthrosis of the hip joint resulting from subchondral fracture with superimposed secondary osteonecrosis

    Yamamoto, Takuaki; Iwamoto, Yukihide [Kyushu University, Department of Orthopaedic Surgery, Fukuoka (Japan); Schneider, Robert [Hospital for Special Surgery, Department of Radiology, New York (United States); Bullough, Peter G. [Hospital for Special Surgery, Department of Laboratory Medicine, New York, NY (United States)


    A 57-year-old woman suffered rapid destruction of both hip joints over a 10 months period. At the first visit, her radiographs demonstrated slight joint space narrowing and acetabular cyst formation in both hips. Five months later, joint space narrowing had further progressed, and intra-articular injection of steroid was given in both hips. However, the hip pain gradually became worse. Five months later, both joint spaces had totally disappeared and both femoral heads had undergone massive collapse. At gross examination, both resected femoral heads showed extensive opaque yellow areas consistent with osteonecrosis. Microscopic examination of these areas revealed evidence of both extensive fracture and callus formation, as well as necrosis throughout, indicating that the osteonecrosis observed in this case was a secondary phenomenon superimposed on pre-existing osteoarthritis and subchondral fracture. There were many pseudogranulomatous lesions in the marrow space and necrotic area, where tiny fragments of bone and articular cartilage, surrounded by histiocytes and giant cells, were embedded, such as are typically seen in rapidly destructive arthrosis. No radiologic or morphologic evidence of primary osteonecrosis was noted. This case indicates that at least some cases of rapidly destructive arthritis are the result of subchondral fracture with superimposed secondary osteonecrosis. (orig.)

  16. [Immediate and long-term results of surgical treatment of patients for traumatic mandibular fracture].

    Kopchak, A V


    The analysis of immediate and long-term results of the surgical treatment of 286 patients, operated for traumatic mandibular fractures in the Department of Oral and Maxillofacial Surgery, National O. O. Bogomolets Medical University. In 67% of patients the anatomical shape of the bone was adequately restored. The presence of residual displacements in other cases was determined by the fracture type and localization, the technical complexity of the surgical intervention, lack of fixation rigidity under certain functional load conditions. In long terms of observation the infection and inflammatory complications were observed in 13.4% of patients, delayed unition and non-unition of bone fragments occurred--in 4.7%, arthosis with persistent dysfunction of the temporomandibular joint--in 6.7%, fibrous ankylosis--in 1.3%. Secondary displacement of fragments was observed in 23.5% of patients due to insufficient stiffness and reliaability of the bone-fixatorsystem. The non-precise reposition of fragments and secondary displacements in the early and late postoperative period were the main cause of occlusal disturbances of various severities, noted in 28% of operated patients, limitation of mouth opening (10%), TMJ disorders and changes in masticatory stereotype (33%), the sensation of pain and discomfort in tough food chewing (35%). A statistical analysis of the effectiveness of different osteosynthesis methods depending on the type and localization of the fracture was carried out and recommendations for usage of fixation devices in clinical practice were given.

  17. Hydraulic fracturing model based on the discrete fracture model and the generalized J integral

    Liu, Z. Q.; Liu, Z. F.; Wang, X. H.; Zeng, B.


    The hydraulic fracturing technique is an effective stimulation for low permeability reservoirs. In fracturing models, one key point is to accurately calculate the flux across the fracture surface and the stress intensity factor. To achieve high precision, the discrete fracture model is recommended to calculate the flux. Using the generalized J integral, the present work obtains an accurate simulation of the stress intensity factor. Based on the above factors, an alternative hydraulic fracturing model is presented. Examples are included to demonstrate the reliability of the proposed model and its ability to model the fracture propagation. Subsequently, the model is used to describe the relationship between the geometry of the fracture and the fracturing equipment parameters. The numerical results indicate that the working pressure and the pump power will significantly influence the fracturing process.

  18. On the fracture of human dentin: Is it stress- orstrain-controlled?

    Nalla, R.K.; Kinney, J.H.; Ritchie, R.O.


    Despite substantial clinical interest in the fractureresistance of human dentin, there is little mechanistic information inarchival literature that can be usefully used to model such fracture. Infact, although the fracture event indent in, akin to other mineralizedtissues like bone, is widely believed to be locally strain-controlled,there has never been any scientific proof to support this belief. Thepresent study seeks to address this issue through the use of a novel setof in vitro experiments in Hanks' balanced salt solution involving adouble-notched bend test geometry, which is designed to discern whetherthe critical failure events involved in the onset of fracture are locallystress- or strain-controlled. Such experiments are further used tocharacterize the notion of "plasticity" in dentin and the interaction ofcracks with the salient microstructural features. It is observed thatfracture in dentin is indeed locally strain-controlled and that thepresence of dentinal tubules does not substantially affect this processof crack initiation and growth. The results presented are believed to becritical steps in the development ofa micromechanical model for thefracture of human dentin that takes into consideration the influence ofboth the microstructure and the local failure mode.

  19. Numerical Evaluation and Optimization of Multiple Hydraulically Fractured Parameters Using a Flow-Stress-Damage Coupled Approach

    Yu Wang


    Full Text Available Multiple-factor analysis and optimization play a critical role in the the ability to maximizethe stimulated reservoir volume (SRV and the success of economic shale gas production. In this paper, taking the typical continental naturally fractured silty laminae shale in China as anexample, response surface methodology (RSM was employed to optimize multiple hydraulic fracturing parameters to maximize the stimulated area in combination with numerical modeling based on the coupled flow-stress-damage (FSD approach. This paper demonstrates hydraulic fracturing effectiveness by defining two indicesnamelythe stimulated reservoir area (SRA and stimulated silty laminae area (SLA. Seven uncertain parameters, such as laminae thickness, spacing, dip angle, cohesion, internal friction angle (IFA, in situ stress difference (SD, and an operational parameter-injection rate (IR with a reasonable range based on silty Laminae Shale, Southeastern Ordos Basin, are used to fit a response of SRA and SLA as the objective function, and finally identity the optimum design under the parameters based on simultaneously maximizingSRA and SLA. In addition, asensitivity analysis of the influential factors is conducted for SRA and SLA. The aim of the study is to improve the artificial ability to control the fracturing network by means of multi-parameteroptimization. This work promises to provide insights into the effective exploitation of unconventional shale gas reservoirs via optimization of the fracturing design for continental shale, Southeastern Ordos Basin, China.

  20. Simulation of three-dimensional tectonic stress fields and quantitative prediction of tectonic fracture within the Damintun Depression, Liaohe Basin, northeast China

    Guo, Peng; Yao, Leihua; Ren, Desheng


    Tectonic fractures are important factors that influence oil and natural gas migration and accumulation within "buried hill" reservoirs. To obtain a quantitative forecast of the development and distribution of reservoir fractures in the Damintun Depression, we analyzed the characteristics of regional structural evolution and paleotectonic stress field setting. A reasonable geological model of the research area was built based on an interpretation of the geological structure, a test for rock mechanics, and experiment on acoustic emission. Thereafter, a three-dimensional paleotectonic stress field during the Yanshan movement was simulated by the finite element method. Rock failure criterion and comprehensive evaluation coefficient of fractures were used to determine the quantitative development of fractures and predict zones that are prone to fracture development. Under an intense Yanshan movement, high stress strength is distributed in the south and northeast parts of the study area, where stress is extremely high. The fracture development zones are mainly controlled by the tectonic stress field and typically located in the same areas as those of high maximum principal and shear stresses. The predicted areas with developed fractures are consistent with the wells with high fracture linear density and in locations with high-producing oil and gas wells.

  1. An analytical and experimental stress analysis of a practical mode II fracture-test specimen

    Chisholm, D. B.; Jones, D. L.


    A boundary collocation method has been employed to determine the Mode II stress intensity factors for a pair of through-the-thickness edge cracks in a finite isotropic plate. An elastostatic analysis has been carried out in terms of the complete Williams stress function employing both even and odd components. The results of the numerical analysis were verified by a two-step procedure whereby the symmetric and antisymmetric portions of the solution were independently compared with existing solutions. The complete solution was verified by comparison with a photoelastic analysis. A compact shear specimen (CSS) of Hysol epoxy resin was loaded in a photoelastic experiment designed to study the isochromatic fringe patterns resulting from the Mode II crack tip stress distribution. The experiment verified that a pure Mode II stress distribution existed in the neighborhood of the crack tips and confirmed the accuracy of the boundary collocation solution for the Mode II stress intensity factors.

  2. The Relationship between Fractures and Tectonic Stress Field in the Extra Low-Permeability Sandstone Reservoir at the South of Western Sichuan Depression

    Zeng Lianbo; Qi Jiafu; Li Yuegang


    The formation and distribution of fractures are controlled by paleotectonic stress field, and their preservative status and effects on development are dominated by the modern stress field. Since Triassic, it has experienced four tectonic movements and developed four sets of tectonic fractures in the extra low-permeability sandstone reservoir at the south of western Sichuan depression. The strikes of fractures are in the S-N, NE-SW, E-W, and NW-SE directions respectively. At the end of Triassic, under the horizontal compression tectonic stress field, for which the maximum principal stress direction was NW-SE,the fractures were well developed near the S-N faults and at the end of NE-SW faults, because of their stress concentration. At the end of Cretaceous, in the horizontal compression stress fields of the NE-SW direction,the stress was obviously lower near the NE-SW faults, thus, fractures mainly developed near the S-N faults.At the end of Neogene-Early Pleistocene, under the horizontal compression tectonic stress fields of E-W direction, stress concentrated near the NE-SW faults and fractures developed at these places, especially at the end of the NE-SE faults, the cross positions of NE-SW, and S-N faults. Therefore, fractures developed mostly near S-N faults and NE-SW faults. At the cross positions of the above two sets of faults, the degree of development of the fractures was the highest. Under the modern stress field of the NW-SE direction, the NW-SE fractures were mainly the seepage ones with tensional state, the best connectivity, the widest aperture, the highest permeability, and the minimum opening pressure.

  3. Femur ultrasound (FemUS)-first clinical results on hip fracture discrimination and estimation of femoral BMD

    Barkmann, R; Dencks, S; Laugier, P


    A quantitative ultrasound (QUS) device for measurements at the proximal femur was developed and tested in vivo (Femur Ultrasound Scanner, FemUS). Hip fracture discrimination was as good as for DXA, and a high correlation with hip BMD was achieved. Our results show promise for enhanced QUS......-based assessment of osteoporosis. INTRODUCTION: Dual X-ray absorptiometry (DXA) at the femur is the best predictor of hip fractures, better than DXA measurements at other sites. Calcaneal quantitative ultrasound (QUS) can be used to estimate the general osteoporotic fracture risk, but no femoral QUS measurement...... has been introduced yet. We developed a QUS scanner for measurements at the femur (Femur Ultrasound Scanner, FemUS) and tested its in vivo performance. METHODS: Using the FemUS device, we obtained femoral QUS and DXA on 32 women with recent hip fractures and 30 controls. Fracture discrimination...

  4. Coupling analysis of unsteady seepage and stress fields in discrete fractures network of rock mass in dam foundation


    The drag force of water flow through single fracture and the coupling characteristics of seepage and stress in single fracture surface are analyzed,and a three dimensional model of coupled unsteady seepage and stress fields is proposed.This model is used to the analysis of foundation rock mass of a high dam.If the coupling effects are considered,the changes of boundary heads have less influence on the inner head of rock mass,and the strong permeability of main fractures appears.If the coupling effects are not considered,the fractures distribution affects the inner head more greatly.When the upstream water head declines,the inner head of dam foundation slightly declines and the hydraulic gradient distribution becomes smoother.A bigger upstream water level declining velocity has a stronger lag effect,meanwhile the values of stress components change more greatly.Therefore the upstream water level declining velocity directly affects the stability of rock mass in dam foundation and we should take into account the above factors to make sure the safety of the dam during reservoir level fluctuation period.

  5. Diagnostic accuracy of the gravity stress test and clinical signs in cases of isolated supination-external rotation-type lateral malleolar fractures.

    Nortunen, S; Flinkkilä, T; Lantto, I; Kortekangas, T; Niinimäki, J; Ohtonen, P; Pakarinen, H


    We prospectively assessed the diagnostic accuracy of the gravity stress test and clinical findings to evaluate the stability of the ankle mortise in patients with supination-external rotation-type fractures of the lateral malleolus without widening of the medial clear space. The cohort included 79 patients with a mean age of 44 years (16 to 82). Two surgeons assessed medial tenderness, swelling and ecchymosis and performed the external rotation (ER) stress test (a reference standard). A diagnostic radiographer performed the gravity stress test. For the gravity stress test, the positive likelihood ratio (LR) was 5.80 with a 95% confidence interval (CI) of 2.75 to 12.27, and the negative LR was 0.15 (95% CI 0.07 to 0.35), suggesting a moderate change from the pre-test probability. Medial tenderness, both alone and in combination with swelling and/or ecchymosis, indicated a small change (positive LR, 2.74 to 3.25; negative LR, 0.38 to 0.47), whereas swelling and ecchymosis indicated only minimal changes (positive LR, 1.41 to 1.65; negative LR, 0.38 to 0.47). In conclusion, when gravity stress test results are in agreement with clinical findings, the result is likely to predict stability of the ankle mortise with an accuracy equivalent to ER stress test results. When clinical examination suggests a medial-side injury, however, the gravity stress test may give a false negative result.

  6. Analysis of Fracturing Network Evolution Behaviors in Random Naturally Fractured Rock Blocks

    Wang, Y.; Li, X.; Zhang, B.


    Shale gas has been discovered in the Upper Triassic Yanchang Formation, Ordos Basin, China. Due to the weak tectonic activities in the shale plays, core observations indicate abundant random non-tectonic micro-fractures in the producing shales. The role of micro-fractures in hydraulic fracturing for shale gas development is currently poorly understood yet potentially critical. In a series of scaled true triaxial laboratory experiments, we investigate the interaction of propagating fracturing network with natural fractures. The influence of dominating factors was studied and analyzed, with an emphasis on non-tectonic fracture density, injection rate, and stress ratio. A new index of P-SRV is proposed to evaluate the fracturing effectiveness. From the test results, three types of fracturing network geometry of radial random net-fractures, partly vertical fracture with random branches, and vertical main fracture with multiple branches were observed. It is suggested from qualitative and quantitative analysis that great micro-fracture density and injection rate tend to maximum the fracturing network; however, it tends to decrease the fracturing network with the increase in horizontal stress ratio. The function fitting results further proved that the injection rate has the most obvious influence on fracturing effectiveness.

  7. Long-term results of nonsurgical management of condylar fractures in children

    Hovinga, J; Boering, G; Stegenga, B


    Twenty-five patients with 28 condylar or subcondylar fractures, sustained during their growth period and treated nonsurgically, have been followed for an average period of 15 years. The fractures were classified as intracapsular, high condylar neck and low condylar neck fractures, In 5 patients, two

  8. SIMULATION OF THE stress-strain state of excavation BOUNDARIES in fractured massifs

    Nizomov Dzhahongir Nizomovich


    Any limiting process, namely, if or and any results are in line with the isotropic medium. The proposed algorithm and calculation pattern may be used to research the concentrated stresses alongside the boundaries of hydrotechnical engineering facilities.

  9. Outcome of Radial Head Arthroplasty in Comminuted Radial Head Fractures: Short and Midterm Results



    Full Text Available Background Comminuted radial head fractures are often associated with secondary injuries and elbow instability. Objectives The aim of this retrospective study was to evaluate how well the modular metallic radial head implant EVOLVE® prosthesis restores functional range of motion (ROM and stability of the elbow in acute care. Patients and Methods Eighty-five patients with comminuted radial head fractures and associated injuries received treatment with an EVOLVE® prosthesis between May 2001 and November 2009. Seventy-five patients were available for follow-up. On average, patients were followed for 41.5 months (33.0: 4.0 - 93.0. Outcome assessment was done on the basis of pain, ROM, strength, radiographic findings, and functional rating scores such as Broberg and Morrey, the Mayo elbow performance index (MEPI, and disabilities of the arm, shoulder and hand (DASH. Our study is currently the largest analysis of clinical outcome of a modular radial head replacement in the literature. Results Overall, there were 2 (2.7% Mason II fractures, 21 (28% Mason III fractures, and 52 (69.3% Mason IV fractures. Arbeitsgemeinschaft fur osteosynthesefragen (AO classification was also determined. Of the 85 patients in our study, 75 were available for follow-up. Follow-up averaged 41.5 months (range, 4 - 93 months. Average scores for the cohort were as follows: Morrey, 85.7 (median 90.2; range 44.4 - 100; MEPI, 83.3 (85.0; 40.0 - 100; and DASH 26.1 points (22.5; 0.0 - 75.8. Mean flexion/extension in the affected joint was 125.7°/16.5°/0° in comparison to the noninjured side 138.5°/0°/1.2°. Mean pronation/supination was 70.5°/0°/67.1° in comparison to the noninjured side 83.6°/0°/84.3°. Handgrip strength of the injured compared to the non-injured arm was 78.8%. The following complications were also documented: 58 patients had periprosthetic radioluceny shown to be neither clinically significant nor relevant according to evaluated scores; 26 patients

  10. Surgical treatment of avulsion fractures at the tibial insertion of the posterior cruciate ligament: functional result

    Marcos Alexandre Barros


    Full Text Available ABSTRACT OBJECTIVE: To objectively and subjectively evaluate the functional result from before to after surgery among patients with a diagnosis of an isolated avulsion fracture of the posterior cruciate ligament who were treated surgically. METHOD: Five patients were evaluated by means of reviewing the medical files, applying the Lysholm questionnaire, physical examination and radiological examination. For the statistical analysis, a significance level of 0.10 and 95% confidence interval were used. RESULTS: According to the Lysholm criteria, all the patients were classified as poor (<64 points before the operation and evolved to a mean of 96 points six months after the operation. We observed that 100% of the posterior drawer cases became negative, taking values less than 5 mm to be negative. CONCLUSION: Surgical methods with stable fixation for treating avulsion fractures at the tibial insertion of the posterior cruciate ligament produce acceptable functional results from the surgical and radiological points of view, with a significance level of 0.042.

  11. Energy Release Rate in hydraulic fracture: can we neglect an impact of the hydraulically induced shear stress?

    Wrobel, Michal; Piccolroaz, Andrea


    A novel hydraulic fracture (HF) formulation is introduced which accounts for the hydraulically induced shear stress at the crack faces. It utilizes a general form of the elasticity operator alongside a revised fracture propagation condition based on the critical value of the energy release rate. It is shown that the revised formulation describes the underlying physics of HF in a more accurate way and is in agreement with the asymptotic behaviour of the linear elastic fracture mechanics. A number of numerical simulations by means of the universal HF algorithm previously developed in Wrobel & Mishuris (2015) are performed in order to: i) compare the modified HF formulation with its classic counterpart and ii) investigate the peculiarities of the former. Computational advantages of the revised HF model are demonstrated. Asymptotic estimations of the main solution elements are provided for the cases of small and large toughness. The modified formulation opens new ways to analyse the physical phenomenon of HF ...

  12. [Stress fracture of the scapular spine associated with rotator cuff dysfunction: Report of 3 cases and review of the literature].

    García-Coiradas, J; Lópiz, Y; Marco, F


    Scapular spine stress fractures have been scarcely reported in the literature. Their pathomechanics, clinical course and treatment are not well established. We review 3 cases in 2 patients that were associated with cuff dysfunction. On follow-up, none of these fractures progressed to healing. Two of them needed osteosynthesis and bone grafting, and the third one became a painless non-union. The authors propose the combination of 3 factors as a reason for this lesion: a functionally impaired cuff, a greater activation of the muscles with origin and insertion in the spine-acromion and a fragile bone. As we believe that these fractures are unstable, and non-union would be expected, their surgical management is recommended. Copyright © 2013 SECOT. Published by Elsevier Espana. All rights reserved.

  13. Early results of thoraco lumbar burst fracture treatment using selective corpectomy and rectangular cage reconstruction

    Liang, Bowei; Huang, Guofeng; Ding, Luobing; Kang, Liangqi; Sha, Mo; Ding, Zhenqi


    Background: Subsidence and late fusion are commonly observed in anterior subtotal corpectomy and reconstruction for treating thoracolumbar burst fractures. The subsidence rate of this surgical method was reported from 19.6% to 75% in the literatures, which would cause treatment failure. Thus, an improvement of anterior surgery technique should be studied to reduce these complications. Materials and Methods: 130 patients of thoracolumbar burst fractures treated by minimal corpectomy, decompression and U cage, between January 2009 and December 2010 were included in this study. The hospital Ethical Committee approved the protocols. The American Spinal Injury Association (ASIA) scale, visual analog scales, and Oswestry Disability Index (ODI) scores were used for clinical evaluation. The local kyphosis angle, vertebral height (one level above the fractured vertebral to one level below), canal stenosis, and fusion status were used to assess radiological outcome. All complications and demographic data such as number of male/female patients, average age, mode of trauma, burst level involved, mean surgery time and blood lost were reported. Results: 120 patients were followed up for 24 months. Most patients had improvement of at least 1 ASIA grade, and all experienced pain reduction. The mean ODI score steadily decreased after the surgery (P 0.05). The average canal stenosis index was increased from 39% to 99% after surgery. No cage subsidence or implant failure was observed. Conclusions: The clinical outcomes described here suggest that the selective corpectomy and rectangular cage reconstruction can effectively promote solid fusion and eliminate complications related to subsidence or implant failure. PMID:28216750

  14. Iliotibial band release as an adjunct to the surgical management of patellar stress fracture in the athlete: a case report and review of the literature

    Keeley Anthony


    Full Text Available Abstract Stress fracture of the patella is rare. In this report, a case of patellar stress fracture occurring in an amateur athlete is presented, and an operative adjunct to the surgical management of this condition is proposed. A review of the English literature identified 21 previous cases of stress fracture of the patella, the majority in young athletes. None of these reports discussed treatment addressing the pathological process contributing to patellar stress fracture. The subject of this case report is a young male netballer who presented with a transverse stress fracture in the inferior third of his patella, on a background of patellofemoral overload. The patient underwent open reduction and internal fixation of his patella, combined with release of the iliotibial band. He returned to training after 6 weeks. The previous literature suggests that operative fixation is indicated for the treatment of displaced patellar stress fractures. Iliotibial band release, as a surgical adjunct to this treatment, may address the pathology of these fractures, and facilitate a return to sport at the highest level.

  15. Iliotibial band release as an adjunct to the surgical management of patellar stress fracture in the athlete: a case report and review of the literature.

    Keeley, Anthony; Bloomfield, Paul; Cairns, Peter; Molnar, Robert


    Stress fracture of the patella is rare. In this report, a case of patellar stress fracture occurring in an amateur athlete is presented, and an operative adjunct to the surgical management of this condition is proposed.A review of the English literature identified 21 previous cases of stress fracture of the patella, the majority in young athletes. None of these reports discussed treatment addressing the pathological process contributing to patellar stress fracture.The subject of this case report is a young male netballer who presented with a transverse stress fracture in the inferior third of his patella, on a background of patellofemoral overload. The patient underwent open reduction and internal fixation of his patella, combined with release of the iliotibial band. He returned to training after 6 weeks.The previous literature suggests that operative fixation is indicated for the treatment of displaced patellar stress fractures. Iliotibial band release, as a surgical adjunct to this treatment, may address the pathology of these fractures, and facilitate a return to sport at the highest level.

  16. The formation of open fractures in cohesive materials, results of scaled analogue and numerical modelling on fault zone porosity development

    Urai J.L.


    Full Text Available We compare analogue and numerical models of dilatational fractures at low confining stress. These structures form an effective conduit for fluid flow in the field, but are difficult to model since they form in cohesive materials at low stresses. We use a truly cohesive powder for the analogue models and a Discrete Element Model (DEM with brittle-elastic bonds for the numerical modelling. We show that despite variations in the model type, small differences in the location of initial fractures and the way these structures link-up to control the evolution of the model, the observed structures are robust. Three structural zones develop where different fault types dominate. In 3D numerical models we show an increase of the porosity on the fault zone with increasing deformation. The progradation direction is shown to be controlled by the position of the fracture. The combination of analogue models with cohesive powder and DEMs with internal cohesion is an excellent tool to study the evolution of open fractures.

  17. Is crack branching under shear loading caused by shear fracture? ——A critical review on maximum circumferential stress theory



    When a crack is subjected to shear force, crack branching usually occurs. Theoretical study shows that the crack branching under shear loading is caused by tensile stress, but not caused by shear fracture. The co-plane shear fracture could be obtained if compressive stress with given direction is applied to the specimen, subsequently, calculated shear fracture toughness, KⅡ C, is larger than KⅠ C. A prerequisite of possible occurrence of mode Ⅱ fracture was proposed. The study of shear fracture shows that the maximum circumferential stress theory considered its criterion as a parametric equation of a curve in KⅠ, KⅡ plane is incorrect; the predicted ratio KⅡ C/KⅠ C=0.866 is incorrect too.

  18. Diaphyseal femoral fractures below the age of six years: Results of plaster application and long term followup

    Nunzio Catena


    Full Text Available Background:In children less than 6 years, the treatment of femoral shaft fracture is often non surgical, using closed reduction and casting. The literature reports many experience about this type of trauma but none of these has a long term followup. We present a retrospective study on a group of femoral diaphyseal fractures treated nonsurgically in children up to 6 years of age, with a minimum of 10 year followup. Materials and Methods:48 cases (36 males/12 females with femoral diaphyseal fractures treated between January 1988 and December 1998 were reviewed. Patients with fractures due to obstetrical trauma and pathologic fractures were excluded. The mean age of the patients was 3.3 ± 1.1 years (range 5 months-6 years. Right side was involved in 21 cases (44%, and left side in 27 cases (56%. In 34 cases (71%, closed reduction was performed and hip spica was applied with the hip and knee flexed to 45΀. In 8 cases (17%, skeletal traction was applied to perform fracture reduction and the traction pin was embedded in plaster while in the remaining 6 cases (12%, the Delitala pressure apparatus was applied after casting. Results:All fractures healed in our study. There were no complications (infection or vascular nervous issues, axial deviations, consolidation delays, or pseudoarthrosis. In 13 cases (27%, followup examinations showed mean lengthening of 1.3 ± 0.75 (range 0.5-2.5 cm of the fractured lower limb. All these patients were treated with skin traction before treatment and presented with 2.08 ± 0.28 cm mean initial femoral shortening. In 1 case (2% with 2.5 cm lengthening, epiphysiodesis of the ipsilateral knee was performed. No patients showed prolonged difficulty with gait disorders. Conclusion:On the basis of our results conservative treatment of femoral shaft fractures in children can be considered less invasive and safe procedure.

  19. [Epidemiology, treatment and results of proximal humeral fractures: experience of a district hospital in a sports- and tourism area].

    Sonderegger, J; Simmen, H-P


    The epidemiology, therapy and results of proximal humeral fractures in a touristic area were investigated and our concept for treatment presented. Between 1.1.1999 and 30.04.2000 adult patients with proximal humeral fractures were included, the fractures classified (Codman/Neer and AO) and results determined after an average of 9 months. 62 adults were treated. 59 (95 %) had an accident during leisure time, mainly skiing accidents (52 %). 7 patients (11 %) had an associated luxation of the shoulder. 51 (82 %) were treated conservatively, 11 (18 %) operatively with a T-plate. The conservatively treated had to wear a Gilchrist-cast for an average of 29 (operatively 13) days, started passive movement after 20 (operatively 9) days, and active movement after 44 (operatively 45) days. The 32 employed (52 %) were not able to work for 46 days on average. Overall, 52 patients (84 %) were totally or mostly satisfied with the result. 5 among the 13 patients (38.5 %) with 3- or 4-part-fractures, and 4 among the 11 operated patients (36.4 %) were not satisfied with the result. Proximal humeral fractures are common skiing injuries, they need a long and intensive treatment and are economically expensive. The Codman/Neer and AO-classifications are equal. The results for simple, mainly conservatively treated fractures (Codman/Neer 1, 2A, 2-part) are good. Complex, mainly operatively treated fractures (Codman/Neer 3- and 4-part) have a much poorer prognosis. Diagnostically the computed tomography with 3-D-reconstruction is recommended for a better representation of the fracture and a safer choice of the therapeutical strategy.

  20. Diagnostic accuracy of 3-T magnetic resonance imaging with 3D T1 VIBE versus computer tomography in pars stress fracture of the lumbar spine

    Ang, E.C.; Robertson, A.F.; Malara, F.A.; O' Shea, T.; Roebert, J.K.; Rotstein, A.H. [Victoria House Medical Imaging, Prahran, Victoria (Australia); Schneider, M.E. [Monash University, Monash Biomedicine Discovery Institute, Department of Medical Imaging and Radiation Sciences, Faculty of Medicine, Nursing and Health Sciences, Clayton, Victoria (Australia)


    To compare the diagnostic accuracy of 3-T magnetic resonance imaging (MRI) with thin-slice 3D T1 VIBE sequence to 128-slice computer tomography (CT) in pars stress fractures of the lumbar spine. 3-T MRI and CT of 24 patients involving 70 pars interarticularis were retrospectively reviewed by four blinded radiologists. The fracture morphology (complete, incomplete, or normal) was assessed on MRI and CT at different time points. Pars interarticularis bone marrow edema (present or absent) was also evaluated on MRI. In total, 14 complete fractures, 31 incomplete fractures and 25 normal pars were detected by CT. Bone marrow edema was seen in seven of the complete and 25 of the incomplete fractures. The overall sensitivity, specificity and accuracy of MRI in detecting fractures (complete and incomplete) were 97.7, 92.3, and 95.7 %, respectively. MRI was 100 % accurate in detecting complete fractures. For incomplete fractures, the sensitivity, specificity, and accuracy of MRI were 96.7, 92.0, and 94.6 %, respectively. 3-T MRI with thin-slice 3D T1 VIBE is 100 % accurate in diagnosing complete pars fractures and has excellent diagnostic ability in the detection and characterization of incomplete pars stress fractures compared to CT. MRI has the added advantages of detecting bone marrow edema and does not employ ionizing radiation. (orig.)

  1. Guiding-controlling technology of coal seam hydraulic fracturing fractures extension

    Zhai; Cheng; Li; Min; Sun; Chen; Zhang; Jianguo; Yang; Wei; Li; Quangui


    Aiming at the uncontrollable problem of extension direction of coal seam hydraulic fracturing,this study analyzed the course of fractures variation around the boreholes in process of hydraulic fracturing,and carried out the numerical simulations to investigate the effect of artificial predetermined fractures on stress distribution around fractured holes.The simulation results show that partial coal mass occurs relatively strong shear failure and forms weak surfaces,and then fractures extended along the desired direction while predetermined fractures changed stress distribution.Directional fracturing makes the fractures link up and the pressure on coal mass is relieved within fractured regions.Combining deep hole controlling blasting with hydraulic fracturing was proposed to realize the extension guiding-controlling technology of coal seam fractures.Industrial experiments prove that this technology can avoid local stress concentration and dramatically widen the pressure relief scope of deep hole controlling blasting.The permeability of fractured coal seam increased significantly,and gas extraction was greatly improved.Besides,regional pressure relief and permeability increase was achieved in this study.

  2. Preliminary functional results of endoscope-assisted transoral treatment of displaced bilateral condylar mandible fractures.

    Schoen, R; Fakler, O; Metzger, M C; Weyer, N; Schmelzeisen, R


    Temporomandibular joint (TMJ) function was evaluated following endoscope-assisted transoral open reduction and miniplate fixation of displaced bilateral condylar mandibular fractures. The transoral treatment of bilateral condylar fractures was performed in 13 patients from May 2000 to December 2004. Eleven of the 13 patients had additional mandibular fractures. Out of 26 fractures of the condylar process, 11 were located at the condylar neck and 15 were subcondylar. One, 6 and 12 months after surgery TMJ function was evaluated. Anatomic reduction was achieved using an endoscope-assisted transoral approach even when the condylar fragment was displaced medially and in fractures with comminution. Good TMJ function was noted 6 and 12 months after surgery. Mouth opening was measured to be more than 40 mm without deviation. Postoperative range of motion with a satisfying lateral excursion was found. Early rehabilitation and pre-injury TMJ function was achieved following minimally invasive anatomic fracture reduction.

  3. Stress fractures of the ankle malleoli diagnosed by ultrasound: a report of 6 cases

    Bianchi, Stefano [CIM SA, Cabinet Imagerie Medicale, Geneve (Switzerland); Luong, Dien Hung [CIM SA, Cabinet Imagerie Medicale, Geneve (Switzerland); University of Montreal, Department of Physical Medicine and Rehabilitation, Montreal (Canada)


    To present the ultrasound appearance of stress fractures (SF) of the ankle malleoli. We present a retrospective review of 6 patients (4 women and 2 men, with an age range of 24-52 years, mean age of 39 years) in which ultrasound diagnosed, together with the clinical findings, an SF of the ankle malleoli. For all of these patients ultrasound was the first imaging technique applied because of a clinical suspicion of soft tissue injuries following excessive exertion. Patients were subsequently examined using standard radiographs and/or MRI. At ultrasound patients showed thickening of the periosteum in all patients, calcified bone callus was evident in 3 out of 6 patients. Cortical irregularities and subcutaneous oedema were found in all but one patient. Colour Doppler showed local hypervascular changes in all patients. Local compression with the transducers during real-time scanning increased pain in all cases. Ultrasound, together with the clinical findings, can diagnose an SF of the ankle malleoli. We suggest that sonologists should include malleolar SF in their differential diagnosis, particularly in the case of perimalleolar pain from over-solicitation. They must also include, as part of every ultrasound examination of the ankle, the evaluation of both malleoli and should be aware of the ultrasound appearance of malleolar SF. If the diagnosis remains uncertain, an MRI should be prescribed. (orig.)

  4. On the predictive capabilities of the shear modified Gurson and the modified Mohr-Coulomb fracture models over a wide range of stress triaxialities and Lode angles

    Dunand, Matthieu; Mohr, Dirk


    The predictive capabilities of the shear-modified Gurson model [Nielsen and Tvergaard, Eng. Fract. Mech. 77, 2010] and the Modified Mohr-Coulomb (MMC) fracture model [Bai and Wierzbicki, Int. J. Fract. 161, 2010] are evaluated. Both phenomenological fracture models are physics-inspired and take the effect of the first and third stress tensor invariants into account in predicting the onset of ductile fracture. The MMC model is based on the assumption that the initiation of fracture is determined by a critical stress state, while the shear-modified Gurson model assumes void growth as the governing mechanism. Fracture experiments on TRIP-assisted steel sheets covering a wide range of stress states (from shear to equibiaxial tension) are used to calibrate and validate these models. The model accuracy is quantified based on the predictions of the displacement to fracture for experiments which have not been used for calibration. It is found that the MMC model predictions agree well with all experiments (less than 4% error), while less accurate predictions are observed for the shear-modified Gurson model. A comparison of plots of the strain to fracture as a function of the stress triaxiality and the normalized third invariant reveals significant differences between the two models except within the vicinity of stress states that have been used for calibration.

  5. Bone Marrow Stem Cells Added to a Hydroxyapatite Scaffold Result in Better Outcomes after Surgical Treatment of Intertrochanteric Hip Fractures

    Joao Torres


    Full Text Available Introduction. Intertrochanteric hip fractures occur in the proximal femur. They are very common in the elderly and are responsible for high rates of morbidity and mortality. The authors hypothesized that adding an autologous bone marrow stem cells concentrate (ABMC to a hydroxyapatite scaffold and placing it in the fracture site would improve the outcome after surgical fixation of intertrochanteric hip fractures. Material and Methods. 30 patients were randomly selected and divided into 2 groups of 15 patients, to receive either the scaffold enriched with the ABMC (Group A during the surgical procedure, or fracture fixation alone (Group B. Results. There was a statistically significant difference in favor of group A at days 30, 60, and 90 for Harris Hip Scores (HHS, at days 30 and 60 for VAS pain scales, for bedridden period and time taken to start partial and total weight bearing (P<0.05. Discussion. These results show a significant benefit of adding a bone marrow enriched scaffold to surgical fixation in intertrochanteric hip fractures, which can significantly reduce the associated morbidity and mortality rates. Conclusion. Bone marrow stem cells added to a hydroxyapatite scaffold result in better outcomes after surgical treatment of intertrochanteric hip fractures.

  6. Effects of stress concentration on low-temperature fracture behavior of A356 alloy

    Ma, Guanghui; Li, Runxia; Li, Rongde


    The effect of stress concentration on the dislocation motion, the Si particles and the crack propagation path in A356 alloy at the temperature of 20 °C to −60 °C was analyzed by scanning electron microscope and optical microscope using a series of notched tensile specimens and normal tensile specimens. The results show that the sensitivity of A356 alloy to the stress concentration increases, the tensile strength and yield strength of normal specimens and notched specimens increase, and the elongation shows a decreasing trend with the decrease of test temperature from 20 °C to −60 °C. The yield strength is not affected by the notch, and the tensile strength is sensitive to the stress concentration. Stress concentration leads to a large number of dislocation generation. Local plastic deformation occurred in the stress concentration region during the tensile process firstly. With the stress concentration in the aluminum matrix between the Si phase and the crack further increasing, the distribution of cracks along the Si phase leads to the cracking of aluminum matrix particle.

  7. Systemic inhibition of canonical Notch signaling results in sustained callus inflammation and alters multiple phases of fracture healing.

    Michael I Dishowitz

    Full Text Available The Notch signaling pathway is an important regulator of embryological bone development, and many aspects of development are recapitulated during bone repair. We have previously reported that Notch signaling components are upregulated during bone fracture healing. However, the significance of the Notch pathway in bone regeneration has not been described. Therefore, the objective of this study was to determine the importance of Notch signaling in regulating bone fracture healing by using a temporally controlled inducible transgenic mouse model (Mx1-Cre;dnMAML(f/- to impair RBPjκ-mediated canonical Notch signaling. The Mx1 promoter was synthetically activated resulting in temporally regulated systemic dnMAML expression just prior to creation of bilateral tibial fractures. This allowed for mice to undergo unaltered embryological and post-natal skeletal development. Results showed that systemic Notch inhibition prolonged expression of inflammatory cytokines and neutrophil cell inflammation, and reduced the proportion of cartilage formation within the callus at 10 days-post-fracture (dpf Notch inhibition did not affect early bone formation at 10dpf, but significantly altered bone maturation and remodeling at 20dpf. Increased bone volume fraction in dnMAML fractures, which was due to a moderate decrease in callus size with no change in bone mass, coincided with increased trabecular thickness but decreased connectivity density, indicating that patterning of bone was altered. Notch inhibition decreased total osteogenic cell density, which was comprised of more osteocytes rather than osteoblasts. dnMAML also decreased osteoclast density, suggesting that osteoclast activity may also be important for altered fracture healing. It is likely that systemic Notch inhibition had both direct effects within cell types as well as indirect effects initiated by temporally upstream events in the fracture healing cascade. Surprisingly, Notch inhibition did not alter

  8. Effect of Crack Tip Stress Concentration Factor on Fracture Resistance in Vacuum Environment


    aluminum alloys and a steel in vacuum environment. The materials investigated were peakaged 7075 -T651, overaged 7075 -T7351, 5083-H131, fully sensitized Al...about twice higher than those of the aluminum alloys; (4) the peakaged 7075 -T651 and overaged 7075 -T7351 have comparable fracture resistance; (5...the fracture resistance of 2024-T351 alloy is higher than 7075 alloys; (6) the fracture resistances of as-received 5083-H131 (5083R) and sensitized

  9. Observed Rates of Lower Extremity Stress Fractures After Implementation of the Army Physical Readiness Training Program at JBSA Fort Sam Houston.

    Chalupa, Robyn L; Aberle, Curtis; Johnson, Anthony E


    Millions of dollars are lost each year to the US military in medical discharges from injuries sustained in the initial training of recruits. Most medical discharges in recruits are related to musculoskeletal overuse injuries, including stress fractures. Any strategies that can reduce injury rates are also likely to reduce rates of medical discharge. This study evaluated the Army Physical Readiness Training (PRT) program which was established to provide a method of physical fitness training that would reduce the number of preventable injuries. We conducted a retrospective study to evaluate the number of lower extremity stress fractures that were diagnosed in the 6 months prior to and 6 months following the implementation of the PRT program. Electronic medical records were queried for specific diagnoses of stress fractures to the pelvis, femoral neck, femoral shaft, tibia, fibula, tarsals and metatarsals. The observed number of diagnoses in each time period were compared using the χ² method. Decrease was shown not only in the overall occurrence of stress fractures, but specifically in the occurrence of stress fractures of the femoral neck, femoral shaft, and tarsals. Our study was able to show a correlation between the PRT program and a decrease in the observed occurrence of lower extremity stress fractures.

  10. Characterizing the influence of stress-induced microcracks on the laboratory strength and fracture development in brittle rocks using a finite-discrete element method-micro discrete fracture network FDEM-mDFN approach

    Pooya Hamdi; Doug Stead; Davide Elmo


    abstract Heterogeneity is an inherent component of rock and may be present in different forms including mineral heterogeneity, geometrical heterogeneity, weak grain boundaries and micro-defects. Microcracks are usually observed in crystalline rocks in two forms: natural and stress-induced; the amount of stress-induced microcracking increases with depth and in-situ stress. Laboratory results indicate that the physical properties of rocks such as strength, deformability, P-wave velocity and permeability are influenced by increase in microcrack intensity. In this study, the finite-discrete element method (FDEM) is used to model microcrack heterogeneity by introducing into a model sample sets of microcracks using the proposed micro discrete fracture network (mDFN) approach. The characteristics of the microcracks required to create mDFN models are obtained through image analyses of thin sections of Lac du Bonnet granite adopted from published literature. A suite of two-dimensional laboratory tests including uniaxial, triaxial compression and Brazilian tests is simulated and the results are compared with laboratory data. The FDEM-mDFN models indicate that micro-heterogeneity has a profound influence on both the me-chanical behavior and resultant fracture pattern. An increase in the microcrack intensity leads to a reduction in the strength of the sample and changes the character of the rock strength envelope. Spalling and axial splitting dominate the failure mode at low confinement while shear failure is the dominant failure mode at high confinement. Numerical results from simulated compression tests show that microcracking reduces the cohesive component of strength alone, and the frictional strength component remains unaffected. Results from simulated Brazilian tests show that the tensile strength is influenced by the presence of microcracks, with a reduction in tensile strength as microcrack intensity increases. The importance of microcrack heterogeneity in reproducing

  11. Angular-stable locking plate fixation of tibial plateau fractures-clinical and radiological midterm results in 101 patients

    Sven Mardian


    Full Text Available Background: Articular reconstruction and stable fixation of tibial plateau fractures and its various subtypes continue to represent a surgical challenge. Only few trials have studied results following angular stable plate fixation. The present study aimed to investigate the clinical, radiological, functional and quality of life results following tibial plateau fractures using angular stable plate fixation. Materials and Methods: 101 patients were retrospectively studied using functional (ROM; KSS; VAS, radiographic (osteoarthritis score, loss of reduction and quality of life (WOMAC; Lysholm scores. There were 46 males and 55 females. The average of patients was 51 years (range 22-77 years. Study groups were assigned according to the AO fracture classification. Results: Mean followup was 57 ± 30 months. Fracture type distribution revealed a significantly (P < 0.001 increased number of type B- (62.4% compared to C-fractures. Functional assessment showed a significantly better total KSS (84.1 ± 15.6 vs. 74.7 ± 18.0; P = 0.01 as well as ROM (active: 124°±17° vs. 116°±15°, P = 0.014; passive: 126°±18° vs. 118 ± 14°, P = 0.017 in the B-fracture group. VAS was found to be markedly higher (P = 0.0039 following type C-fractures. Rating osteoarthritis secondary to a tibial plateau fracture as a function of injury severity (r = 0.485; P < 0.001 and relating the loss of reduction to the grade of evolving osteoarthritis (r = 0.643;P < 0.001 a positive correlation was found. Quality of life showed significantly improved results for Lysholm score (P = 0.004 following B-fractures with low overall values for the WOMAC score. Conclusion: Presented data provide sufficient evidence that anatomic restoration of tibial plateau fractures with angular stable plate fixation result in decreased loss of reduction and declined incidence of posttraumatic osteoarthritis, thereby providing acceptable mid to long term outcome.

  12. Review of Hydraulic Fracturing for Preconditioning in Cave Mining

    He, Q.; Suorineni, F. T.; Oh, J.


    Hydraulic fracturing has been used in cave mining for preconditioning the orebody following its successful application in the oil and gas industries. In this paper, the state of the art of hydraulic fracturing as a preconditioning method in cave mining is presented. Procedures are provided on how to implement prescribed hydraulic fracturing by which effective preconditioning can be realized in any in situ stress condition. Preconditioning is effective in cave mining when an additional fracture set is introduced into the rock mass. Previous studies on cave mining hydraulic fracturing focused on field applications, hydraulic fracture growth measurement and the interaction between hydraulic fractures and natural fractures. The review in this paper reveals that the orientation of the current cave mining hydraulic fractures is dictated by and is perpendicular to the minimum in situ stress orientation. In some geotechnical conditions, these orientation-uncontrollable hydraulic fractures have limited preconditioning efficiency because they do not necessarily result in reduced fragmentation sizes and a blocky orebody through the introduction of an additional fracture set. This implies that if the minimum in situ stress orientation is vertical and favors the creation of horizontal hydraulic fractures, in a rock mass that is already dominated by horizontal joints, no additional fracture set is added to that rock mass to increase its blockiness to enable it cave. Therefore, two approaches that have the potential to create orientation-controllable hydraulic fractures in cave mining with the potential to introduce additional fracture set as desired are proposed to fill this gap. These approaches take advantage of directional hydraulic fracturing and the stress shadow effect, which can re-orientate the hydraulic fracture propagation trajectory against its theoretical predicted direction. Proppants are suggested to be introduced into the cave mining industry to enhance the

  13. No Increase in Fractures After Stopping Hormone Therapy: Results From the Women's Health Initiative.

    Watts, Nelson B; Cauley, Jane A; Jackson, Rebecca D; LaCroix, Andrea Z; Lewis, Cora E; Manson, JoAnn E; Neuner, Joan M; Phillips, Lawrence S; Stefanick, Marcia L; Wactawski-Wende, Jean; Crandall, Carolyn


    The Women's Health Initiative (WHI) hormone therapy (HT) trials showed protection against hip and total fractures, but a later observational report suggested loss of benefit and a rebound increased risk after cessation of HT. The purpose of this study was to examine fractures after discontinuation of HT. Two placebo-controlled randomized trials served as the study setting. Study patients included WHI participants (N = 15,187) who continued active HT or placebo through the intervention period and who did not take HT in the postintervention period. Trial interventions included conjugated equine estrogen (CEE) plus medroxyprogesterone acetate (MPA) in naturally menopausal women and CEE alone in women with prior hysterectomy. Total fractures and hip fractures through 5 years after discontinuation of HT were recorded. Hip fractures were infrequent (∼2.5 per 1000 person-years); this finding was similar between trials and in former HT and placebo groups. There was no difference in total fractures in the CEE + MPA trial for former HT vs former placebo users (28.9 per 1000 person-years and 29.9 per 1000 person-years, respectively; hazard ratio [HR], 0.97; 95% confidence interval [CI], 0.87 to 1.09; P = 0.63); however, in the CEE-alone trial, total fractures were higher in former placebo users (36.9 per 1000 person-years) compared with the former active group (31.1 per 1000 person-years), a finding that was suggestive of a residual benefit of CEE against total fractures (HR, 0.85; 95% CI, 0.73 to 0.98; P = 0.03). We found no evidence for increased fracture risk, either sustained or transient, for former HT users compared with former placebo users after stopping HT. There was residual benefit for total fractures in former HT users from the CEE-alone study.

  14. A Study of Structural Stress Technique for Fracture Prediction of an Auto-Mobile Clutch Snap-Ring

    Kim, Ju Hee [Korea Military Academy, Seoul (Korea, Republic of); Myeong, Man Sik [Samsung Display, Suwon (Korea, Republic of); Oh, Chang Sik [KINS, Daejeon (Korea, Republic of); Kim, Yun Jae [Korea Univ., Sejong (Korea, Republic of)


    The endurance reliability assessment of a highly complex mechanism is generally predicted by the fatigue life based on simple stress analysis. This study discusses various fatigue life assessment techniques for an automobile clutch snap ring. Finite element analyses were conducted to determine the structural stress on the snap ring. Structural stress that is insensitive in regards to the mesh size and type definition is presented in this study. The structural stress definition is consistent with elementary structural mechanics theory and provides an effective measure of a stress state that pertains to fatigue behavior of welded joints in the form of both membrane and bending components. Numerical procedures for both solid models and shell or plate element models are presented to demonstrate the mesh-size insensitivity when extracting the structural stress parameters. Conventional finite element models can be used with the structural stress calculations as a post-processing procedure. The two major implications from this research were: (a) structural stresses pertaining to fatigue behavior can be consistently calculated in a mesh-insensitive manner regardless of the types of finite element models; and (b) by comparing with the clutch snap-ring fatigue test data, we should predict the fatigue fractures of an automobile clutch snap ring using this method.

  15. An integrated workflow for stress and flow modelling using outcrop-derived discrete fracture networks

    Bisdom, Kevin; Nick, Hamid; Bertotti, Giovanni


    stresssensitive fracture permeability and matrix flow to determine the full permeability tensor. The applicability of this workflow is illustrated using an outcropping carbonate pavement in the Potiguar basin in Brazil, from which 1082 fractures are digitised. The permeability tensor for a range of matrix...


    Mondeep Gayan


    Full Text Available BACKGROUND External Fixation (EF and Open Reduction and Internal Fixation (ORIF have been the traditional surgical modalities for unstable distal radius fractures. The Locking Compression Plates (LCP acting as “internal external fixators” are particularly valuable in difficult situations of fractures. We undertook a study to evaluate the outcome of unstable distal radius fractures treated with ORIF with LCP versus those treated by ligamentotaxis with external fixators. MATERIALS AND METHODS A comparative study was carried out in a tertiary care centre with 30 cases of unstable distal radius fractures (15 cases in each group. In one group, open reduction and internal fixation with distal radius volar locking compression plate was carried out and in the other group ligamentotaxis with external fixator was done. The patients were treated and followed up over a period of one and a half year between June 2011 to November 2012. The fractures were classified according to AO classification (Arbeitsgemeinschaft für Osteosynthesefragen: German for “Association for the Study of Internal Fixation” or AO. The functional results were evaluated at the end of 6 months according to Demerit point system of Gartland and Werley modified by Sarmiento (1975 and the anatomical results as per Lindstrom criteria (1959 modified by Sarmiento (1980. RESULTS Overall 86.66% (13 cases had good-to-excellent anatomical results in external fixator group as compared to 93.33% (14 cases in LCP group. The functional outcome was excellent in 80% (12 and good in 13.33% (2 cases in external fixator group as compared to 66.66% (10 excellent and 26.66% (4 good in LCP group. CONCLUSION Both open reduction and internal fixation with locking compression plate and ligamentotaxis with external fixators are good treatment modalities for unstable distal radius fractures. However, the choice should be guided by the fracture configuration, surgeons’ experience and patient’s profile.

  17. Permeability reduction by pyrobitumen, mineralization, and stress along large natural fractures in sandstones at 18,300 ft. depth: Destruction of a reservoir

    Lorenz, J.C. [SPE, Richardson, TX (United States)]|[Sandia National Lab., Albuquerque, NM (United States); Billingsley, R.L.; Evans, L.W.


    Production of gas from the Frontier Formation at 18,300 R depth in the Frewen No. 4 Deep well, eastern Green River basin (Wyoming), was uneconomic despite the presence of numerous open natural fractures. Initial production tested at 500 MCFD, but dropped from 360 MCFD to 140 MCFD during a 10-day production test, and the well was abandoned. Examination of the fractures in the core suggests several probable reasons for this poor production. One factor is the presence of a hydrocarbon residue (carbon) which filled much of the porosity left in the smaller fractures after mineralization. An equally important factor is probably the reorientation of the in situ horizontal compressive stress to a trend normal to the main fractures, and which now acts to close fracture apertures rapidly during reservoir drawdown. This data set has unpleasant implications for the search for similar, deep fractured reservoirs.

  18. The association between hematological and inflammatory factors and stress fractures among female military recruits.

    Merkel, Drorit; Moran, Daniel S; Yanovich, Ran; Evans, Rachel K; Finestone, Aharon S; Constantini, Naama; Israeli, Eran


    With the growing number of females accepted for combat-related military duties in the Israeli Defense Forces, their special needs should be addressed. Previous studies on females in combat training have found a high prevalence of iron deficiency at recruitment as well as an increased rate of stress fractures (SF) and overuse injuries during training when compared with males. The aim of this study was to assess the correlation between hematological and inflammatory variables and SF occurrence among military recruits during basic training. Three gender-integrated light infantry units were followed prospectively. Female recruits inducted for medic and dental assistants' courses were followed for comparison. Hemoglobin, iron, transferrin, ferritin, C-reactive protein, and interleukin-6 levels were measured for all participants at recruitment and at 2 and 4 months of training. SF were diagnosed radiographically or scintigraphically according to the Israeli Defense Forces protocol. A total of 438 subjects were recruited (female combatants = 227, male combatants = 83, noncombatant females = 128). At induction, 18% of female combatants had anemia compared with 8% of males and 19% of noncombatants. Iron deficiency was noted in 40%, 6%, and 38%, respectively. There were no clinically significant changes during training. Twelve percent of female combatants developed SF, whereas none occurred among male combatants or noncombatants. Subjects sustaining an SF had significantly lower levels of serum iron and iron saturation. A high incidence of anemia as well as iron deficiency was found in this young asymptomatic cohort, with no significant change during training. The lower level of iron in female combatants sustaining SF warrants further investigation.

  19. Fluid Compressibility Effects during Hydraulic Fracture: an Opportunity for Gas Fracture Revival

    Mighani, S.; Boulenouar, A.; Moradian, Z.; Evans, J. B.; Bernabe, Y.


    Hydraulic fracturing results when internal pore pressure is increased above a critical value. As the fracture extends, the fluid flows to the crack tip. The fracturing process depends strongly on the physical properties of both the porous solid and the fluid (e.g. porosity and elastic moduli for the solid, viscosity and compressibility for the fluid). It is also affected by the in-situ stress and pore pressure conditions. Here, we focus on the effect of fluid properties on hydraulic fracturing under conventional triaxial loading. Cylinders of Solnhofen limestone (a fine-grained, low permeability rock) were prepared with a central borehole through which different pressurized fluids such as oil, water or argon, were introduced. Preliminary experiments were performed using a confining pressure of 5 MPa and axial stress of 7 MPa. Our goal was to monitor fracture extension using strain gauges, acoustic emissions (AE) recording and ultrasonic velocity measurements. We also tried to compare the data with analytical models of fracture propagation. Initial tests showed that simple bi-wing fractures form when the fracturing fluid is relatively incompressible. With argon as pore fluid, a complex fracture network was formed. We also observed that the breakdown pressure was higher with argon than with less compressible fluids. After fracturing occurred, we cycled fluid pressure for several times. During the first cycles, re-opening of the fracture was associated with additional propagation. In general, it took 4 cycles to inhibit further propagation. Analytical models suggest that initial fractures occurring with compressible fluids tend to stabilize. Hence, formation and extension of additional fractures may occur, leading to a more complex morphology. Conversely, fractures formed by incompressible fluids remain critically stressed as they extend, thus producing a simple bi-wing fracture. Using compressible fracturing fluids could be a suitable candidate for an efficient

  20. Risk factors for hip fracture. MEDOS study: results of the Toulouse Centre.

    Ribot, C; Tremollieres, F; Pouilles, J M; Albarede, J L; Mansat, M; Utheza, G; Bonneu, M; Bonnissent, P; Ricoeur, C


    The development of preventive strategies for hip fractures requires better identification of risk factors. The MEDOS study was designed to study prospectively the incidence of hip fracture in 14 centres from six countries and characterise risk factors. At one centre (Toulouse), data were gathered from questionnaires completed by 386 cases of hip fracture aged over 50 years and 848 age- and sex-matched controls over a 12-month period. Of the 935 variables of the MEDOS questionnaire, 235, grouped into 56 items, were statistically analysed. Odds ratios (and 95% confidence intervals) were estimated for each variable from a multiple stepwise logistic regression model. The population comprised 19.2% men and 80.8% women, with a mean age of 80 +/- 8.8 years; 80% were living in an urban area and 76% with their family. Of the 17 significant variables, moderate excess weight and a high nutritional intake of calcium were associated with a decreased risk of hip fracture. Loss of autonomy, a higher height than normal (> 1SD), and a history of previous fractures significantly increased the risk of fracture. Interestingly, all these variables accounted for only 18% of the risk of hip fracture.

  1. Fracture Mechanics

    Zehnder, Alan T


    Fracture mechanics is a vast and growing field. This book develops the basic elements needed for both fracture research and engineering practice. The emphasis is on continuum mechanics models for energy flows and crack-tip stress- and deformation fields in elastic and elastic-plastic materials. In addition to a brief discussion of computational fracture methods, the text includes practical sections on fracture criteria, fracture toughness testing, and methods for measuring stress intensity factors and energy release rates. Class-tested at Cornell, this book is designed for students, researchers and practitioners interested in understanding and contributing to a diverse and vital field of knowledge. Alan Zehnder joined the faculty at Cornell University in 1988. Since then he has served in a number of leadership roles including Chair of the Department of Theoretical and Applied Mechanics, and Director of the Sibley School of Mechanical and Aerospace Engineering.  He teaches applied mechanics and his research t...

  2. Stress Resultant Based Elasto-Viscoplastic Thick Shell Model

    Pawel Woelke


    Full Text Available The current paper presents enhancement introduced to the elasto-viscoplastic shell formulation, which serves as a theoretical base for the finite element code EPSA (Elasto-Plastic Shell Analysis [1–3]. The shell equations used in EPSA are modified to account for transverse shear deformation, which is important in the analysis of thick plates and shells, as well as composite laminates. Transverse shear forces calculated from transverse shear strains are introduced into a rate-dependent yield function, which is similar to Iliushin's yield surface expressed in terms of stress resultants and stress couples [12]. The hardening rule defined by Bieniek and Funaro [4], which allows for representation of the Bauschinger effect on a moment-curvature plane, was previously adopted in EPSA and is used here in the same form. Viscoplastic strain rates are calculated, taking into account the transverse shears. Only non-layered shells are considered in this work.

  3. Stress fracture of hamate's hook: case report with emphasis to the imaging findings; Fratura de stress do gancho do hamato: relato de caso com enfase aos achados de imagem

    Carvalho, Leonardo Fontenelle de [Clinica de Diagnostico por Imagem (CDPI), Rio de Janeiro, RJ (Brazil); Vianna, Evandro Miguelote; Domingues, Romulo; Domingues, Romeu Cortes [Clinicas Multimagem, Rio de Janeiro, RJ (Brazil); Metsavaht, Leonardo [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)]. E-mail:


    Stress fractures of the hook of the hamate are related to sports that use devices such as golf clubs, rackets and baseball bats. Because usually there is no history of obvious trauma, the diagnosis necessitates better knowledge of the lesion and high index of suspicion. The authors report a case of stress fracture of the hook of the hamate in a golf player with diagnosis and follow-up done with magnetic resonance and multislice computer tomography. (author)

  4. The late treatment of vertical orbital dystopia resulting from an orbital roof fracture.

    Horowitz, J H; Persing, J A; Winn, H R; Edgerton, M T


    Traumatic fracture of the orbital roof is uncommon and it may be unrecognized at the time of injury. In this article we describe a patient with progressive vertical orbital dystopia four years after he sustained a fracture of his "frontal" bone. Surgical exploration revealed an orbital roof fracture complicated by a chronic dural leak. An intracranial-extracranial approach through a modified frontal craniotomy provided excellent visualization to elevate the bony orbit and globe safely and repair the dural tear. Our study illustrates the need to correct residual soft tissue deformity at a second operation. Orbital roof fracture is a complex injury and is best treated by a multispecialty team using the methods learned from the treatment of patients with congenital orbital dystopia.

  5. Results of Laboratory Scale Fracture Tests on Rock/Cement Interfaces

    Um, Wooyong; Jung, Hun Bok


    A number of pure cement and cement-basalt interface samples were subjected to a range of compressive loads to form internal fractures. X-ray microtomography was used to visualize the formation and growth of internal fractures in three dimensions as a function of compressive loads. This laboratory data will be incorporated into a geomechanics model to predict the risk of CO2 leakage through wellbores during geologic carbon storage.

  6. Long-term functional results after short-segment pedicle fixation of thoracolumbar fractures

    Mølmer, Michael; Gehrchen, Poul Martin; Dahl, Benny


    A retrospective study to assess the health-related quality of life in patients undergoing posterior fixation of thoracolumbar fractures, and to compare the outcome with norm scores and HRQL in patients undergoing surgical treatment for degenerative conditions of the spine.......A retrospective study to assess the health-related quality of life in patients undergoing posterior fixation of thoracolumbar fractures, and to compare the outcome with norm scores and HRQL in patients undergoing surgical treatment for degenerative conditions of the spine....

  7. Minimally invasive plate osteosynthesis for humeral shaft fractures: are results reproducible?

    Concha, Juan M; Sandoval, Alejandro; Streubel, Philipp N


    Minimally invasive plate osteosynthesis (MIPO) has been advocated as a safe approach to humeral shaft fracture management. We evaluated the reproducibility of this technique in a regional hospital. Thirty-five patients underwent MIPO of humerus shaft fractures. Fifteen patients had an open fracture, six a preoperative radial nerve palsy, and nine a concomitant thoracic, musculoskeletal or vascular injury. At an average 12-month follow-up, 91% of fractures healed after a mean of 12 weeks (range, 8-16). Two infections occurred. Final alignment averaged 4° of varus (range, 5° of valgus to 20° of varus). Active elbow ROM averaged 114° (range, 60-135°) and was less than 100° in nine elbows. Five of six preoperative radial nerve injuries recovered spontaneously. Healing and infection rates in this study are consistent with those reported in the literature. Lower elbow ROM and higher fracture angulation at healing were nevertheless found. MIPO is technically demanding and requires adequate intraoperative imaging and surgical experience in order to obtain adequate fracture alignment. Brachialis muscle scarring and inadequate postoperative rehabilitation may be involved in limited elbow range of motion.

  8. Posttraumatic Stress Disorder Patients and Results of Violent Behavior

    Taner Oznur


    Full Text Available AIM: High levels of anger and aggression in post-traumatic stress disorder lead to unfavorable social, legal, physical and economic results to family members and the other social layers as much as patients. In this study, it is aimed to investigate the relation between both alcohol-cigarette consumption ratios and anger levels, characteristics of aggressive behaviors and the judicial outcome in cases diagnosed post-traumatic stress disorder due to armed conflict. METHODS: 38 cases diagnosed as post-traumatic stress disorder were included to the study. Pre- and post-traumatic alcohol/cigarette consumption amounts and aggressive behaviors are determined. Impact of Events Scale (Revised (IES-R was used for evaluating post-traumatic stress disorder symptom patterns and severity, Buss Perry Aggression Questionnaire was used for measuring anger and aggression levels, and Taylor and #8217;s Violence Rating Scale was used for evaluating the judicial outcome of aggression. RESULTS: 23 of cases (60.6% were married with children, 13 of cases (34.25 were single and 2 of cases (5.2% were divorced.18 of cases (47.4% were graduate. IES-R total score was 66,9 +/- 12,7, Buss Perry total score was 111,3 +/- 20,5, and Taylor and #8217;s Violence Rate was 2,5 +/- 1,0. When the pre- and post-traumatic aggressive behaviors were compared; physical violence to the partner was increased more than ten times, Physical and verbal violence to social individuals were increased more than four and seven times, respectively. And also it is observed that inflicting damage to property was increased 17 times, reckless driving was increased 11 times, and self-mutilation was increased 5 times. Alcohol consumption was determined as 0 (0 - 126 g/day for pre-trauma cases and 16.5 (0 - 294 g/day for post-trauma cases. Cigarette smoking was determined as 5 (0 and #8211; 40 cigarette/day for pre-trauma cases and 30 (0 -60 cigarette/day for post-trauma cases. CONCLUSION: Post

  9. Fixation of 3- and 4-part proximal humerus fractures using the PHILOS plate: mid-term results.

    Gaheer, Rajinder Singh; Hawkins, Amanda


    Treatment of unstable, displaced, and comminuted fractures of the proximal humerus remains challenging, and optimal treatment continues to be controversial. Fifty-six patients with displaced 3- and 4-part fractures of the proximal humerus had open reduction and internal fixation using the proximal humeral internal locking system (PHILOS) plate (Synthes, Stratec Medical Ltd, Mezzovico, Switzerland). Data were collected retrospectively, and clinical and radiological outcomes were assessed. Mean follow-up was 40 months (range, 18-62 months). The study shows that the PHILOS plate gives good results in the treatment of displaced 3- and 4-part fractures of the proximal humerus. Good fracture stability can be achieved early, allowing early mobilization without compromising fracture union. Most importantly, it requires minimal soft tissue dissection, does not need contouring, and gives good stability. No differences were observed in the functional outcomes of patients younger and older than 65 years. Few complications were associated with the plate, and the number of ≥2 surgeries was minimal. The complications noted were 1 case each of superficial wound infection, failure of the plate, and persistent stiffness. One patient had screw perforation of the humeral head articular surface, and 1 had subacromial impingement. Of the 32 patients who had been in active employment before the injury, 28 returned to their previous occupation.

  10. The Prevention of Postmenopausal Osteoporotic Fractures: Results of the Health Technology Assessment of a New Antiosteoporotic Drug

    Chiara de Waure


    Full Text Available Objective. The Health Technology Assessment (HTA approach was applied to denosumab in the prevention of osteoporotic fractures in postmenopausal women. Method. Epidemiological, clinical, technical, economic, organizational, and ethical aspects were considered. Medical electronic databases were accessed to evaluate osteoporosis epidemiology and therapeutical approaches. A budget impact and a cost-effectiveness analyses were performed to assess economic implications. Clinical benefits and patient needs were considered with respect to organizational and ethical evaluation. Results. In Italy around four millions women are affected by osteoporosis and have a higher risk for fractures with 70,000 women being hospitalized every year. Bisphosphonates and strontium ranelate are recommended as first line treatment for the prevention of osteoporotic fractures. Denosumab is effective in reducing vertebral, nonvertebral, and hip/femoral fractures with an advantage of being administered subcutaneously every six months. The budget impact analysis estimated a reduction in costs for the National Health Service with the introduction of denosumab. Furthermore, the economic analysis demonstrated that denosumab is cost-effective in comparison to oral bisphosphonates and strontium ranelate. Denosumab can be administered in outpatients by involving General Practitioners in the management. Ethical evaluation is positive because of its efficacy and compliance. Conclusion. Denosumab could add value in the prevention of osteoporotic fractures.

  11. Fracture of summer perennial sea ice by ocean swell as a result of Arctic storms

    Asplin, Matthew G.; Galley, Ryan; Barber, David G.; Prinsenberg, Simon


    The Arctic summer minimum sea ice extent has experienced a decreasing trend since 1979, with an extreme minimum extent of 4.27 × 106 km2 in September 2007, and a similar minimum in 2011. Large expanses of open water in the Siberian, Laptev, Chukchi, and Beaufort Seas result from declining summer sea ice cover, and consequently introduce long fetch within the Arctic Basin. Strong winds from migratory cyclones coupled with increasing fetch generate large waves which can propagate into the pack ice and break it up. On 06 September 2009, we observed the intrusion of large swells into the multiyear pack ice approximately 250 km from the ice edge. These large swells induced nearly instantaneous widespread fracturing of the multiyear pack ice, reducing the large, (>1 km diameter) parent ice floes to small (100-150 m diameter) floes. This process increased the total ice floe perimeter exposed to the open ocean, allowing for more efficient distribution of energy from ocean heat fluxes, and incoming radiation into the floes, thereby enhancing lateral melting. This process of sea ice decay is therefore presented as a potential positive feedback process that will accelerate the loss of Arctic sea ice.

  12. Exercise-induced dehydration with and without environmental heat stress results in increased oxidative stress.

    Hillman, Angela R; Vince, Rebecca V; Taylor, Lee; McNaughton, Lars; Mitchell, Nigel; Siegler, Jason


    While in vitro work has revealed that dehydration and hyperthermia can elicit increased cellular and oxidative stress, in vivo research linking dehydration, hyperthermia, and oxidative stress is limited. The purpose of this study was to investigate the effects of exercise-induced dehydration with and without hyperthermia on oxidative stress. Seven healthy male, trained cyclists (power output (W) at lactate threshold (LT): 199 ± 19 W) completed 90 min of cycling exercise at 95% LT followed by a 5-km time trial (TT) in 4 trials: (i) euhydration in a warm environment (EU-W, control), (ii) dehydration in a warm environment (DE-W), (iii) euhydration in a thermoneutral environment (EU-T), and (iv) dehydration in a thermoneutral environment (DE-T) (W: 33.9 ± 0.9 °C; T: 23.0 ± 1.0 °C). Oxidized glutathione (GSSG) increased significantly postexercise in dehydration trials only (DE-W: p dehydration trials (p = 0.08 for both). Monocyte heat shock protein 72 (HSP72) concentration was increased (p = 0.01) while lymphocyte HSP32 concentration was decreased for all trials (p = 0.02). Exercise-induced dehydration led to an increase in GSSG concentration while maintenance of euhydration attenuated these increases regardless of environmental condition. Additionally, we found evidence of increased cellular stress (measured via HSP) during all trials independent of hydration status and environment. Finally, both 90-min and 5-km TT performances were reduced during only the DE-W trial, likely a result of combined cellular stress, hyperthermia, and dehydration. These findings highlight the importance of fluid consumption during exercise to attenuate thermal and oxidative stress during prolonged exercise in the heat.

  13. Stress fracture of the second metatarsal and sprain of lisfranc joint in a pre-professional ballet dancer.

    Kriz, Peter; Rafferty, Jason; Evangelista, Peter; Van Valkenburg, Scott; DiGiovanni, Christopher


    We present the case of a 14-year-old pre-professional ballerina that demonstrates common features of two conditions affecting the midfoot that are often missed or subject to delay in diagnosis in such young athletes: 1. stress fractures at the base of the second metatarsal, and 2. sprain of the Lisfranc joint complex. While these represent potentially career-altering injuries in the professional dancer, this case demonstrates that a high index of clinical suspicion, careful physical exam, appropriate radiographic assessment, and prompt treatment are essential to achieving the best possible outcome.

  14. Simulated evolution of fractures and fracture networks subject to thermal cooling: A coupled discrete element and heat conduction model

    Huang, Hai; Plummer, Mitchell; Podgorney, Robert


    Advancement of EGS requires improved prediction of fracture development and growth during reservoir stimulation and long-term operation. This, in turn, requires better understanding of the dynamics of the strongly coupled thermo-hydro-mechanical (THM) processes within fractured rocks. We have developed a physically based rock deformation and fracture propagation simulator by using a quasi-static discrete element model (DEM) to model mechanical rock deformation and fracture propagation induced by thermal stress and fluid pressure changes. We also developed a network model to simulate fluid flow and heat transport in both fractures and porous rock. In this paper, we describe results of simulations in which the DEM model and network flow & heat transport model are coupled together to provide realistic simulation of the changes of apertures and permeability of fractures and fracture networks induced by thermal cooling and fluid pressure changes within fractures. Various processes, such as Stokes flow in low velocity pores, convection-dominated heat transport in fractures, heat exchange between fluid-filled fractures and solid rock, heat conduction through low-permeability matrices and associated mechanical deformations are all incorporated into the coupled model. The effects of confining stresses, developing thermal stress and injection pressure on the permeability evolution of fracture and fracture networks are systematically investigated. Results are summarized in terms of implications for the development and evolution of fracture distribution during hydrofracturing and thermal stimulation for EGS.

  15. Clinical results of olecranon fractures treated with multiplanar locked intramedullary nailing.

    Argintar, Evan; Cohen, Mark; Eglseder, Andrew; Edwards, Scott


    Proximal ulnar fractures have traditionally been fixed with either tension band wiring or plate and screw fixation. These traditional techniques often irritate the surrounding soft tissues, potentially leading to subsequent secondary hardware removal surgeries. Intramedullary proximal ulnar fixation provides similar rigid fixation, however, no review yet exists to support the clinical use of currently available implants. To investigate the clinical and radiographic short-term outcomes for multiplanar locked intramedullary nails used to treat proximal ulnar fractures. A retrospective multicenter review was conducted in 28 patients with unstable olecranon fractures treated with a new multiplanar locked intramedullary nailing system (OlecraNail, Mylad Orthopedic Solutions, McLean, VA). Radiographic union was estimated, and serial clinical outcome up to one year was assessed by strength, motion, pain (visual analog scale), and a subcutaneous ulna border palpation (SCUBP) test to assess hardware prominence. All fractures achieved union by 8 weeks. At 12 weeks postoperatively, all motion was within 10 degrees of the contralateral side in all directions. Of the 18 patients who underwent SCUBP testing, all 18 patients reported to have no pain at 12 weeks. At one-year follow-up, all patients had resumed normal activities, including work and athletics. All of the patients who underwent the SCUBP testing continued to have no pain. Multiplanar locked intramedullary nails offer effective management for proximal ulna fractures similar to those reported with plating techniques. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

  16. Simulation of complex fracture networks influenced by natural fractures in shale gas reservoir

    Zhao Jinzhou


    Full Text Available When hydraulic fractures intersect with natural fractures, the geometry and complexity of a fracture network are determined by the initiation and propagation pattern which is affected by a number of factors. Based on the fracture mechanics, the criterion for initiation and propagation of a fracture was introduced to analyze the tendency of a propagating angle and factors affecting propagating pressure. On this basis, a mathematic model with a complex fracture network was established to investigate how the fracture network form changes with different parameters, including rock mechanics, in-situ stress distribution, fracture properties, and frac treatment parameters. The solving process of this model was accelerated by classifying the calculation nodes on the extending direction of the fracture by equal pressure gradients, and solving the geometrical parameters prior to the iteration fitting flow distribution. With the initiation and propagation criterion as the bases for the propagation of branch fractures, this method decreased the iteration times through eliminating the fitting of the fracture length in conventional 3D fracture simulation. The simulation results indicated that the formation with abundant natural fractures and smaller in-situ stress difference is sufficient conditions for fracture network development. If the pressure in the hydraulic fractures can be kept at a high level by temporary sealing or diversion, the branch fractures will propagate further with minor curvature radius, thus enlarging the reservoir stimulation area. The simulated shape of fracture network can be well matched with the field microseismic mapping in data point range and distribution density, validating the accuracy of this model.

  17. Results of Patello-Tibial Cerclage Wire Technique for Comminuted Patella Fractures Treated with Partial Patellectomy

    Ender Alagöz


    Full Text Available Aim: Partial patellectomy and patellotibial cerclage technique used in comminuted inferior pole patellar fractures were evaluated and the results were discussed. Methods: Thirteen patients who have undergone partial distal patellar excision were evaluated in the study. In all patients, the inferior pole of the patella was resected, patellar tendon was sutured to the proximal patellar fragment and patellotibial cerclage was performed. At the last visit, the patients were evaluated using measurement of the distance between the superior pole of the patella and the tibial tubercle, the Lysholm knee scoring scale, knee range of motion and thigh circumference measurement. Results: The mean flexion value was 131.10 (±4.6 in normal knees and 117.20 (±8.0 in operated knees. The mean thigh diameter was 49.5 (±3.7 cm and 46.4 (±4.5 cm in normal knees and in operated knees, respectively. The mean Lysholm knee score in the patient group was 84.3 (±17.1 points. The mean distance between the superior pole of the patella and the tibial tubercle was 10.6 (±1.0 cm in normal knees and 10.1 (±1.2 cm in operated knees. The exstensor mechanism was intact in all patients and no revision surgery was performed. Conclusion: Patellotibial cerclage technique performed after partial patellectomy permits early motion and protects patients from harmful effects of immobilization; and good functional results are obtained if patients start early knee motion.

  18. Effect of Stress-Induced Phase Transformation on the Fracture Toughness of Fe3Al Intermetallic Reinforced with Yttria-Partially Stabilized Zirconia Particles

    Amiri Talischi, Lima; Samadi, Ahad


    In this study, fracture toughness and microhardness of Fe3Al intermetallic reinforced with yttria-partially stabilized zirconia (Y-PSZ) particles were investigated. Fe3Al/Y-PSZ composites containing up to 20 wt pct of Y-PSZ were fabricated by hot pressing of powder mixtures. It is found that the microhardness and fracture toughness of Fe3Al intermetallic increase by adding Y-PSZ particles. The maximal levels of fracture toughness and microhardness correspond to Fe3Al-10 wt pct Y-PSZ composite with the fracture toughness of 23.1 MPa√m and the microhardness of 645 HV. The improvement in fracture toughness could be related to the stress-induced structural transformation of zirconia particles from tetragonal to monoclinic which causes crack deflection and prevents crack propagation.

  19. Preliminary results from osteosynthesis using Ender nails by means of a percutaneous technique, in humeral diaphysis fractures in adults☆

    Godinho, Glaydson Gomes; França, Flávio de Oliveira; Freitas, José Márcio Alves; Santos, Flávio Márcio Lago; Correa, Guilherme de Almeida Sellos; Maia, Lucas Russo


    Objective To demonstrate the clinical and functional results from treatment of humeral diaphysis fractures using Ender nails. Methods Eighteen patients who underwent osteosynthesis of humeral diaphysis fractures using Ender nails were evaluated. In addition to the clinical and radiographic evaluations, patients with a minimum of one year of follow-up were assessed by means of the Constant, American Shoulder and Elbow Surgeons (ASES), Mayo Clinic and Simple Shoulder Value (SSV) functional scores, and in relation to the degree of satisfaction with the final result. The fixation technique used was by means of an anterograde percutaneous route. Results All the patients achieved fracture consolidation, after a mean of 2.9 months (ranging from 2 to 4 months). The mean Constant score was 85.7 (ranging from 54 to 100) and the mean ASES score was 95.9 (ranging from 76 to 100). All the patients achieved the maximum score on the Mayo Clinic scale. Conclusion Fixation of humeral diaphysis fractures using Ender nails by means of a percutaneous technique was shown to be a method with promising preliminary results. PMID:26417566

  20. Cost of osteoporosis-related fracture in Italy. Results of the BLOCK study

    Luca Degli Esposti


    Full Text Available The objectives of the present study were to calculate the cost of illness of osteoporosis and to assess drug utilization patterns in postmenopausal women after a fracture-related hospitalization. The study subjects were enrolled from a large population-based administrative database. Female patients (age ≥ 65 years who were hospitalized for a typical osteoporotic fracture between 1/1/2000 and 31/12/2005 were included. Patients were classified as exposed/unexposed to treatment according to the presence/absence of at least one prescription for an osteoporosis-related medication in the 6 months following the discharge date. Treatment adherence was calculated for patients who were exposed to bisphosphonate therapy and was defined as at least 80% of treatment coverage during the follow-up period of 18 months after the discharge date. Hospitalizations, medications, diagnostic tests, laboratory tests and specialist visits during the 18-month follow-up period were collected and classified as osteoporosis-related or non-related to osteoporosis. A total of 12,376 patients were included in the study (mean age ± SD, 79.1 ± 7.5 years, out of which 97.9% (n = 12,110 were hospitalized due to an osteoporosis-related fracture and only 2.1% (n = 266 had general osteoporosis diagnosis. Among the 12,110 women with a fracture, 15.2% (n = 1,845 had a subsequent fracture-related hospitalization (63.8% of the patients had hip fracture. Only 32.3% (n = 4,001 of all included patients was exposed to osteoporosis-related medications and out of those patients exposed to bisphosphonates (n = 860 only 34.2% (n = 294 was adherent to therapy. The average cost per patient was € 4,481, of which € 1,089 was for osteoporosis-related and € 3,392 for non-osteoporosis-related items. The average cost of a matching cohort of patients without hospitalizations for fracture was € 2,339. Among osteoporosis-related costs, 87.0% was due to hospitalizations for subsequent fractures

  1. Hydraulic fracture propagation modeling and data-based fracture identification

    Zhou, Jing

    Successful shale gas and tight oil production is enabled by the engineering innovation of horizontal drilling and hydraulic fracturing. Hydraulically induced fractures will most likely deviate from the bi-wing planar pattern and generate complex fracture networks due to mechanical interactions and reservoir heterogeneity, both of which render the conventional fracture simulators insufficient to characterize the fractured reservoir. Moreover, in reservoirs with ultra-low permeability, the natural fractures are widely distributed, which will result in hydraulic fractures branching and merging at the interface and consequently lead to the creation of more complex fracture networks. Thus, developing a reliable hydraulic fracturing simulator, including both mechanical interaction and fluid flow, is critical in maximizing hydrocarbon recovery and optimizing fracture/well design and completion strategy in multistage horizontal wells. A novel fully coupled reservoir flow and geomechanics model based on the dual-lattice system is developed to simulate multiple nonplanar fractures' propagation in both homogeneous and heterogeneous reservoirs with or without pre-existing natural fractures. Initiation, growth, and coalescence of the microcracks will lead to the generation of macroscopic fractures, which is explicitly mimicked by failure and removal of bonds between particles from the discrete element network. This physics-based modeling approach leads to realistic fracture patterns without using the empirical rock failure and fracture propagation criteria required in conventional continuum methods. Based on this model, a sensitivity study is performed to investigate the effects of perforation spacing, in-situ stress anisotropy, rock properties (Young's modulus, Poisson's ratio, and compressive strength), fluid properties, and natural fracture properties on hydraulic fracture propagation. In addition, since reservoirs are buried thousands of feet below the surface, the

  2. Digital x-ray radiogrammetry identifies women at risk of osteoporotic fracture: results from a prospective study

    Bach-Mortensen, Pernille; Hyldstrup, Lars; Appleyard, Merete;


    Using digital X-ray radiogrammetry (DXR) on hand radiographs from a large population-based study, 1,370 postmenopausal women were evaluated in a prospective fashion; fracture occurrence was compared with DXR measurements of historic radiographs. Further, the aim of the study was to evaluate factors...... suffered a fracture. Odds ratios (ORs) per 1 standard deviation decline in DXR-BMD were statistically significant for fracture in the groups of wrist fractures, proximal humerus fractures, vertebral fractures, and other fractures as well as in the total fracture group. In the hip fracture group, the P...

  3. Functional Results of Intercondylar Fractures of the Humerus Fixed with Dual Y-Plate; A Technical Note

    Swagat Mahapatra


    Full Text Available Objective: To evaluate and report the functional results of surgical management of intercondylar fractures of the humerus in adults using a novel dual plating technique. Methods: A total number of 60 patients with Riseborough and Radin type II, III, and IV intercondylar humerus fractures were operated with open reduction through a Trans-olecranon approach and internal fixation using two plates in inverted-Y configuration. Patients were followed for 3 weeks, 3 and 6 months were evaluated using the Mayo Elbow performance score and Quick-DASH score. Results: There were 50(83.33%men and 10 (16.67%women with mean age of 34.9 ± 12.63 years. 63.3% of the cases were following Motor vehicle accident and rest following fall. The right upper limb was more commonly affected than the left side. Riseborough and Radin type II fractures accounted for 3.33% of cases; type III fractures accounted for 50% of cases and type IV accounted for 46.67%. Excellent to Good results were seen in almost 80% of cases as per the Mayo Elbow performance score at 6-month follow-up. Quick-DASH scores for the series at 6-month follow-up was on average of 15.96 ± 9.92. Conclusion: Dual plating in inverted Y configuration offers a reliable fixation, which permits early mobilization and good functional outcome.

  4. Functional Results of Intercondylar Fractures of the Humerus Fixed with Dual Y-Plate; A Technical Note  

    Mahapatra, Swagat; Abraham, Vineet Thomas


    Objective: To evaluate and report the functional results of surgical management of intercondylar fractures of the humerus in adults using a novel dual plating technique. Methods: A total number of 60 patients with Riseborough and Radin type II, III, and IV intercondylar humerus fractures were operated with open reduction through a Trans-olecranon approach and internal fixation using two plates in inverted-Y configuration. Patients were followed for 3 weeks, 3 and 6 months were evaluated using the Mayo Elbow performance score and Quick-DASH score. Results: There were 50(83.33%)men and 10 (16.67%)women with mean age of 34.9 ± 12.63 years. 63.3% of the cases were following Motor vehicle accident and rest following fall. The right upper limb was more commonly affected than the left side. Riseborough and Radin type II fractures accounted for 3.33% of cases; type III fractures accounted for 50% of cases and type IV accounted for 46.67%. Excellent to Good results were seen in almost 80% of cases as per the Mayo Elbow performance score at 6-month follow-up. Quick-DASH scores for the series at 6-month follow-up was on average of 15.96 ± 9.92. Conclusion: Dual plating in inverted Y configuration offers a reliable fixation, which permits early mobilization and good functional outcome.

  5. Theoretical Analysis of the Mechanism of Fracture Network Propagation with Stimulated Reservoir Volume (SRV Fracturing in Tight Oil Reservoirs.

    Yuliang Su

    Full Text Available Stimulated reservoir volume (SRV fracturing in tight oil reservoirs often induces complex fracture-network growth, which has a fundamentally different formation mechanism from traditional planar bi-winged fracturing. To reveal the mechanism of fracture network propagation, this paper employs a modified displacement discontinuity method (DDM, mechanical mechanism analysis and initiation and propagation criteria for the theoretical model of fracture network propagation and its derivation. A reasonable solution of the theoretical model for a tight oil reservoir is obtained and verified by a numerical discrete method. Through theoretical calculation and computer programming, the variation rules of formation stress fields, hydraulic fracture propagation patterns (FPP and branch fracture propagation angles and pressures are analyzed. The results show that during the process of fracture propagation, the initial orientation of the principal stress deflects, and the stress fields at the fracture tips change dramatically in the region surrounding the fracture. Whether the ideal fracture network can be produced depends on the geological conditions and on the engineering treatments. This study has both theoretical significance and practical application value by contributing to a better understanding of fracture network propagation mechanisms in unconventional oil/gas reservoirs and to the improvement of the science and design efficiency of reservoir fracturing.

  6. Theoretical Analysis of the Mechanism of Fracture Network Propagation with Stimulated Reservoir Volume (SRV) Fracturing in Tight Oil Reservoirs.

    Su, Yuliang; Ren, Long; Meng, Fankun; Xu, Chen; Wang, Wendong


    Stimulated reservoir volume (SRV) fracturing in tight oil reservoirs often induces complex fracture-network growth, which has a fundamentally different formation mechanism from traditional planar bi-winged fracturing. To reveal the mechanism of fracture network propagation, this paper employs a modified displacement discontinuity method (DDM), mechanical mechanism analysis and initiation and propagation criteria for the theoretical model of fracture network propagation and its derivation. A reasonable solution of the theoretical model for a tight oil reservoir is obtained and verified by a numerical discrete method. Through theoretical calculation and computer programming, the variation rules of formation stress fields, hydraulic fracture propagation patterns (FPP) and branch fracture propagation angles and pressures are analyzed. The results show that during the process of fracture propagation, the initial orientation of the principal stress deflects, and the stress fields at the fracture tips change dramatically in the region surrounding the fracture. Whether the ideal fracture network can be produced depends on the geological conditions and on the engineering treatments. This study has both theoretical significance and practical application value by contributing to a better understanding of fracture network propagation mechanisms in unconventional oil/gas reservoirs and to the improvement of the science and design efficiency of reservoir fracturing.

  7. [Demonstration of the impossibility of simultaneous Dupuytren and Destot fractures in the result of the car-pedestrian collision].

    Gusarov, A A; Fetisov, V A; Kucheryavets, Yu O


    This article reports the results of the commission forensic medical expertise undertaken to evaluate the possibility of severe injury to the ankle joint resulting from the road traffic accident as exemplified by the collision of a VAS 21043 car moving backward with a pedestrian. It was shown that the injury to the victim's right lower leg included the tear of the right crural deltoid ligament, the open communicated fracture of the lower third of fibular diaphysis with the displacement of the distal fragment, the lacerated wound in the lower third of the right leg, the rupture of distal tibiofibular synedesmosis, the closed communicated fracture of the posterior edge of the tibia without displacement, and outward subluxation of the right foot. According to the classification accepted in orthopedics , this variant of the injury to the ankle joint is a combination of the classical «complete» Dupuytren fracture and the Destot-type fracture. The analysis of the mechanism underlying formation of such injury has shown that it was a consequence of the indirect injurious action in the absence of the primary impact without the car running over the victim's leg.

  8. Hydraulic fracturing fluid migration in the subsurface: A review and expanded modeling results

    Birdsell, Daniel T.; Rajaram, Harihar; Dempsey, David; Viswanathan, Hari S.


    Understanding the transport of hydraulic fracturing (HF) fluid that is injected into the deep subsurface for shale gas extraction is important to ensure that shallow drinking water aquifers are not contaminated. Topographically driven flow, overpressured shale reservoirs, permeable pathways such as faults or leaky wellbores, the increased formation pressure due to HF fluid injection, and the density contrast of the HF fluid to the surrounding brine can encourage upward HF fluid migration. In contrast, the very low shale permeability and capillary imbibition of water into partially saturated shale may sequester much of the HF fluid, and well production will remove HF fluid from the subsurface. We review the literature on important aspects of HF fluid migration. Single-phase flow and transport simulations are performed to quantify how much HF fluid is removed via the wellbore with flowback and produced water, how much reaches overlying aquifers, and how much is permanently sequestered by capillary imbibition, which is treated as a sink term based on a semianalytical, one-dimensional solution for two-phase flow. These simulations include all of the important aspects of HF fluid migration identified in the literature review and are performed in five stages to faithfully represent the typical operation of a hydraulically fractured well. No fracturing fluid reaches the aquifer without a permeable pathway. In the presence of a permeable pathway, 10 times more fracturing fluid reaches the aquifer if well production and capillary imbibition are not included in the model.

  9. Femoral shaft fracture fixed with intramedullary nailing in a child resulting in femoral neck narrowing deformity and fracture

    WAN Lin; ZHAO Lin; LIU Yan-qing; WANG Xu; LIU Jing-sheng


    @@ Treatment of factures in children is different from that of adults because improper internal fixation,including selection of internal fixation device and epiphysis approaching,may cause epiphysis injury,which may result in a series of secondary lesions in bone development,such as growth arrest,limb length discrepancy, osteonecrosis, and other deformities.

  10. Comparative study of the results of compound tibial shaft fractures treated by Ilizarov ring fixators and limb reconstruction system fixators

    Chandra Prakash Pal; Harish Kumar; Deepak Kumar; K.S.Dinkar; Vivek Mittal; Naveen Kumar Singh


    Purpose: Ilizarov ring fixator and limb reconstruction system (LRS) fixators have been used in the management of complex tibial fractures with severe soft tissue injuries, compound tibial fractures, and infected tibial nonunion for which conventional internal fixation cannot be contemplated.Fracture union and distraction osteogenesis can be done simultaneously with these external fixators, allowing early weight bearing.Several previous studies have shown almost equal results of rail and ring fixators for the compound tibial shaft fractures.Thus we performed a prospective study to evaluate the union rate, functional outcome and amount of limb lengthening after the treatment of compound tibial shaft fractures with or without infected nonunion by ring or LRS fixators.Methods: This prospective study was done at Sarojini Naidu Medical College and Hospital, Agra, India and included 32 patients of compound tibial shaft fractures with or without infected nonunion.There were 26 males and 6 females and the average age was 40 years.Patients were randomly divided into two groups (n =16 for each): one underwent Ilizarov fixation and the other received LRS fixation.Cases were followed up for 3-24 months, 6 months on average from September 2012 to October 2014.Functional and radiological outcomes were assessed using the Association for the Study and Application of Methods of Ilizarov (ASAMI) criteria for both rail and ring fixators.Results: Union was achieved in all cases.Radiological outcome was found excellent in 68.75%, good in 18.75% and fair in 12.50% of cases treated by rail fixators whereas it was excellent in 56.25%, good in 18.75%, fair in 12.50% and poor in 12.50% of cases treated by ring fixators.Functional result was satisfactory in 75.00% of cases treated by rail fixator and 68.75% of cases treated by ring fixators whereas the corresponding rate of unsatisfactory was 25.00% vs.31.25%.Conclusion: In our short-term assessment, LRS fixators show a

  11. Stress history and fracture pattern in fault-related folds based on limit analysis: application to the Sub-Andean thrust belt of Bolivia

    Barbe, Charlotte; Leroy, Yves; Ben Miloud, Camille


    A methodology is proposed to construct the stress history of a complex fault-related fold in which the deformation mechanisms are essentially frictional. To illustrate the approach, fours steps of the deformation of an initially horizontally layered sand/silicone laboratory experiment (Driehaus et al., J. of Struc. Geol., 65, 2014) are analysed with the kinematic approach of limit analysis (LA). The stress, conjugate to the virtual velocity gradient in the sense of mechanicam power, is a proxy for the true statically admmissible stress field which prevailed over the structure. The material properties, friction angles and cohesion, including their time evolution are selected such that the deformation pattern predicted by the LA is consistent with the two main thrusting events, the first forward and the second backward once the layers have sufficiently rotated. The fractures associated to the stress field determined at each step are convected on today configuration to define the complete pattern which should be observed. The end results are presented along virtual vertical wells and could be used within the oil industry at an early phase of exploration to prepare drealing operations.

  12. Field-Scale Effective Matrix Diffusion Coefficient for FracturedRock: Results From Literature Survey

    Zhou, Quanlin; Liu, Hui Hai; Molz, Fred J.; Zhang, Yingqi; Bodvarsson, Gudmundur S.


    Matrix diffusion is an important mechanism for solutetransport in fractured rock. We recently conducted a literature survey onthe effective matrix diffusion coefficient, Dem, a key parameter fordescribing matrix diffusion processes at the field scale. Forty fieldtracer tests at 15 fractured geologic sites were surveyed and selectedfor study, based on data availability and quality. Field-scale Dem valueswere calculated, either directly using data reported in the literature orby reanalyzing the corresponding field tracer tests. Surveyed dataindicate that the effective-matrix-diffusion-coefficient factor FD(defined as the ratio of Dem to the lab-scale matrix diffusioncoefficient [Dem]of the same tracer) is generally larger than one,indicating that the effective matrix diffusion coefficient in the fieldis comparatively larger than the matrix diffusion coefficient at therock-core scale. This larger value could be attributed to the manymass-transfer processes at different scales in naturally heterogeneous,fractured rock systems. Furthermore, we observed a moderate trend towardsystematic increase in the emDFmDDF value with observation scale,indicating that the effective matrix diffusion coefficient is likely tobe statistically scale dependent. The FD value ranges from 1 to 10,000for observation scales from 5 to 2,000 m. At a given scale, the FD valuevaries by two orders of magnitude, reflecting the influence of differingdegrees of fractured rock heterogeneity at different sites. In addition,the surveyed data indicate that field-scale longitudinal dispersivitygenerally increases with observation scale, which is consistent withprevious studies. The scale-dependent field-scale matrix diffusioncoefficient (and dispersivity) may have significant implications forassessing long-term, large-scale radionuclide and contaminant transportevents in fractured rock, both for nuclear waste disposal and contaminantremediation.

  13. Induced damage in Carrara Marble as a result of long-term low-magnitude environmental stresses

    Voigtlaender, Anne; Leith, Kerry; Krautblatter, Michael; Walter, Jens M.


    Damage of intact rock is commonly driven by the interaction of long-term low-magnitude external environmental stresses in combination with surface chemistry, rather than short-term loading in excess of intact rock strength. In order to determine the contribution of environmental stresses to the propagation of micro- and macroscopic fractures under natural environmental conditions we undertook long-term three-point bending tests on large size Carrara Marble specimens. The interaction of mechanical stresses induced by external loading and corrosive conditions (e.g. the presence of water) at the tip of a pre-existing crack is termed stress corrosion. We investigate stress corrosion below saw cut notches in wet and dry samples of Carrara Marble (M1-5, each 10cm x 10cm x 110cm). These were pre-loaded to about 66% of their assumed ultimate strength (determined by the fracture toughness (Kic) calculated for the crack tip). Two marble beams (M1, M3) were initially loaded to 22% and three (M2, M4, M5) to 55% of Kic. CaC03 saturated water was continuously dripped in the notch of samples --M1-4 to create corrosive conditions, while M5 was kept dry. After a three-week bedding period, loading on sample M1 was increased to 55%, M2 and M5 to 77% and M3 and M4 to 85% of Kic respectively. The tests were interrupted prior to failure of the specimens in order to allow the assessment of the crack-tip structure. During the testing period we used classical strain gages and acoustic emission sensors to measure strain and elastic stress changes through coda wave interferometry. Temperature and humidity were monitored and the outflowing fluid was collected for future analysis, throughout. The effect of induced damage on residual intrinsic stresses was evaluated using neutron diffraction on the SALSA instrument at the Institute Laue-Langevin (ILL, Grenoble, France), while texture measurements were undertaken using the X-ray goniometer at the Geoscience Center, University Göttingen, and

  14. Fracture network growth for prediction of fracture characteristics and connectivity in tight reservoir rocks

    Barnhoorn, A.; Cox, S.F.


    Fracturing experiments on very low-porosity dolomite rocks shows a difference in growth of fracture networks by stress-driven fracturing and fluid-driven fracturing. Stress-driven fracture growth, in the absence of fluid pressure, initially forms fractures randomly throughout the rocks followed by g

  15. Three dimensional finite element analysis of anatomic distal radius Nitinol memory connector treating distal radius fracture

    苏佳灿; 张春才; 禹宝庆; 许硕贵; 王家林; 纪方; 张雪松; 吴建国; 王保华; 薛召军; 丁祖泉


    Objective: To study the memory biomechanical character of anatomic distal radius Nitinol memory connector (DRMC) in treating distal radius fracture. Methods: Establishing three dimensional model and finite element analysis, we calculated the stress in and around the fracture faces when distal radius fracture was fixated with DRMC. Results: Axial holding stress produced by holding part of DRMC on distal radius was 14.66 MPa. The maximum stress of holding part was 40-70 MPa, the minimum stress was 3-7 MPa,and the stress of compression part was 20-40 MPa. Conclusion: The distribution of stress produced by DRMC around the fracture line is reasonable, and axial holding stress can help stabilize fracture during earlier period. The existence of longitudal compression and memory effect can transfer fixated disused section into developed section and enhance fracture healing.

  16. The treatment of complex proximal humeral fractures: analysis of the results of 55 cases treated with PHILOS plate.

    Fattoretto, D; Borgo, A; Iacobellis, C


    Complex proximal humerus fractures are often difficult to treat. Their frequency is high, especially in the elderly, and their treatment is still controversial. The aim of this study was to analyze the clinical and radiological results achieved by patients with complex proximal humerus fractures, treated with PHILOS plate only. A cohort of 55 patients was selected. The mean age was 63.4 (range 33-89), while the mean follow-up time was 21.5 months (range 6-75). Clinical outcome was evaluated with the "Constant-Murley shoulder score." All the informations about the presence of complications were gathered, and radiological images were used to calculate the head-shaft angle. The overall mean Constant score was 61.93 ± 18.59, the Individual CS was 70 ± 20 % and the Relative CS was 83 ± 23 %. No significant differences were found between fractures Neer 3 and Neer 4 and between the surgical approaches (delta-split vs. delto-pectoral). Six patients had a fracture with dislocation, seven patients (12.7 %) had complications while in four patients a head-shaft angle beyond the normal range was found. Osteosynthesis with PHILOS plate is stable in the greater part of the cases, and it allows an earlier rehabilitation and so a good functional result, which could be compromised by a prolonged immobilization. Therefore, PHILOS plate is a good option for the treatment of complex proximal humerus fractures.

  17. Preliminary Results of In-situ Stress Measurements along the Longmenshan Fault Zone after the Wenchuan Ms 8.0 Earthquake

    WU Manlu; ZHANG Yueqiao; LIAO Chunting; CHEN Qunce; MA Yinsheng; WU Jinsheng; YAN Junfeng; OU Mingyi


    Four months after the Wenchuan Ms 8 earthquake in western Sichuan, China, in situ stress measurements were carried out along the Longmenshan fault zone with the purpose of obtaining stress parameters for earthquake hazard assessment. In-situ stresses were measured in three new boreholes by using overcoring with the piezomagnetic stress gauges for shallow depths and hydraulic fracturing for lower depths. The maximum horizontal stress in shallow depths (~20 m) is about 4.3 MPa, oriented NI9°E, in the epicenter area at Yingxiu Town, about 9.7 MPa, oriented N51°W, at Baoxing County in the southwestern Longmenshan range, and about 2.6 MPa, oriented N39°E, near Kangding in the southernmost zone of the Longmenshan range. Hydraulic fracturing at borehole depths from 100 to 400 m shows a tendency towards increasing stress with depth. A comparison with the results measured before the Wenchuan earthquake along the Longmenshan zone and in the Tibetan Plateau demonstrates that the stress level remains relatively high in the southwestern segment of the Longmenshan range, and is still moderate in the epicenter zone. These results provide a key appraisal for future assessment of earthquake hazards of the Longmenshan fault zone and the aftershock occurrences of the Wenchuan earthquake.

  18. Fracture strength and principal stress fields during crush testing of the SiC layer in TRISO-coated fuel particles

    Davis, Brian C.; Ward, Logan; Butt, Darryl P.; Fillery, Brent; Reimanis, Ivar


    Diametrical compression testing is an important technique to evaluate fracture properties of the SiC layer in TRISO-coated nuclear fuel particles. This study was conducted to expand the understanding and improve the methodology of the test. An analytic solution and multiple FEA models are used to determine the development of the principal stress fields in the SiC shell during a crush test. An ideal fracture condition where the diametrical compression test best mimics in-service internal pressurization conditions was discovered. For a small set of empirical data points, results from different analysis methodologies were input to an iterative Weibull equation set to determine characteristic strength (332.9 MPa) and Weibull modulus (3.80). These results correlate well with published research. It is shown that SiC shell asphericity is currently the limiting factor of greatest concern to obtaining repeatable results. Improvements to the FEA are the only apparent method for incorporating asphericity and improving accuracy.

  19. A displaced stress fracture of the femoral neck in an adolescent female distance runner with female athlete triad: A case report.

    Okamoto, Shinichi; Arai, Yuji; Hara, Kunio; Tsuzihara, Takashi; Kubo, Toshikazu


    This report presents a case of a displaced stress fracture of the femoral neck in an adolescent female distance runner with amenorrhea. Both reduction and internal fixation were performed early after the injury. At 24 months postoperatively, magnetic resonance imaging and bone scintigraphy showed no positive signs of femoral head necrosis and bone union was confirmed on plain X-ray. A medical examination for the presence of the signs of the female athlete triad by checking weight, calorie intake and menstrual cycles is most important to prevent such stress fractures. Athletes as well as their coaches or parents therefore need to understand female athlete triad.

  20. A displaced stress fracture of the femoral neck in an adolescent female distance runner with female athlete triad: A case report

    Okamoto Shinichi


    Full Text Available Abstract This report presents a case of a displaced stress fracture of the femoral neck in an adolescent female distance runner with amenorrhea. Both reduction and internal fixation were performed early after the injury. At 24 months postoperatively, magnetic resonance imaging and bone scintigraphy showed no positive signs of femoral head necrosis and bone union was confirmed on plain X-ray. A medical examination for the presence of the signs of the female athlete triad by checking weight, calorie intake and menstrual cycles is most important to prevent such stress fractures. Athletes as well as their coaches or parents therefore need to understand female athlete triad.

  1. Analysis of the Slab Temperature, Thermal Stresses and Fractures Computed with the Implementation of Local and Average Boundary Conditions in the Secondary Cooling Zones

    Hadała B.


    Full Text Available The numerical simulations of the temperature fields have been accomplished for slab casting made of a low carbon steel. The casting process of slab of 1500 mm in width and 225 mm in height has been modeled. Two types of boundary condition models of heat transfer have been employed in numerical simulations. The heat transfer coefficient in the first boundary condition model was calculated from the formula which takes into account the slab surface temperature and water flow rate in each secondary cooling zone. The second boundary condition model defines the heat transfer coefficient around each water spray nozzle. The temperature fields resulting from the average in zones water flow rate and from the nozzles arrangement have been compared. The thermal stresses and deformations resulted from such temperature field have given higher values of fracture criterion at slab corners.

  2. [Acetabular fractures].

    Gänsslen, A; Oestern, H J


    Treatment of acetabular fractures requires extensive knowledge of the bony anatomy, the amount of possible exposure of the bone with the selected approaches and fracture type-dependent indications of operative treatment. Classification of the fracture with detailed analysis of the fracture morphology is the basis for decision making and planning. The primary treatment aim is the anatomic reconstruction of the acetabulum which results in optimal long-term results.The basis of this overview is the presentation of standard treatment concepts in acetabular fracture surgery. Beside characteristics of the acetabular bony anatomy, biomechanical and pathomechanical principles and the relevant radiological anatomy, the treatment options, both conservative and operative and basic principles of the indications for standard surgical approaches will be discussed.The special fracture type is discussed in detail regarding incidence, injury mechanism, concomitant injuries, options for conservative and operative treatment, quality of operative reduction and long-term results.Furthermore, epidemiological data on typical postoperative complications are evaluated.


    V. M. Shapovalov


    Full Text Available The authors give the clinical case of successful surgical treatment of patient with tibia's pathologic fracture by intramedullary nailing with bone grafting. The disadvantages of such patients' treatment by plaster immobilization and by some invasive methods like vascular autografting by Ilizarov's method and bone plating were also discussed. The obvious benefits of proposed surgical treatment technique of observed patient category are shown.

  4. Ulnar Nerve Injury as a Result of Galeazzi Fracture: A Case Report and Literature Review.

    Roettges, Paul; Turker, Tolga


    Sparse documentation of Galeazzi fracture with associated nerve injury exists in the medical literature. The purpose of this report is to review the available literature in regard to incidence, nerve injury type, treatment strategies, and expected outcomes. We present a classic Galeazzi fracture dislocation with associated complete ulnar nerve transection injury at the level of the wrist. After rigid internal bony stabilization, allograft nerve repair was performed. The patient's presentation, operative management, recovery, and a thorough literature review are discussed. Fracture union was attained with near full wrist and elbow range of motion. Despite lack of ulnar nerve function return, the patient was able to resume manual labor occupation. Despite its close proximity to the dislocating distal radioulnar joint (DRUJ), thorough review reveals rare associated ulnar nerve palsy. If there is suspicion for nerve injury in the setting of open DRUJ dislocation, the nerve should be explored to identify possible entrapment or transection. Literature supports likely return of nerve function in cases of intact nerve; however, management of nerve transection remains debatable.

  5. [Medication as a risk factor for falls resulting in severe fractures in the elderly].

    Coutinho Ed, Evandro da Silva Freire; Silva, Sidney Dutra da


    Falls leading to fractures among the elderly are a major public problem. A case-control study was conducted on the use of certain drugs as a risk factor for hospitalization due to fractures after falls among individuals aged 60 years or over in the city of Rio de Janeiro, Brazil. One hundred sixty-nine cases and 315 in-patient controls were matched by age, sex, and hospital. Odds ratios (OR) adjusted for potential confounders were calculated using conditional logistic regression. Increased risk of such accidents was found for calcium channel antagonists (OR = 1.96, 1.16-3.30) and benzodiazepines (OR = 2.09, 1.08-4.05), and decreased risk was associated with diuretics (OR = 0.40, 0.20-0.80). Antacids, digitalis, and laxatives were associated with reduced risk of fractures after falls that reached borderline statistical significance (0.05 < p < 0.10). The findings highlight the need to weigh risks and benefits of medication in the elderly. It is also important to advise such individuals and their families on how to avoid falls when such medication proves necessary.

  6. CT virtual reality in the preoperative workup of malunited distal radius fractures: preliminary results

    Rieger, Michael; Gruber, Hannes; Jaschke, Werner R. [Innsbruck University Hospital, Department of Radiology I, Innsbruck (Austria); Gabl, Markus [Innsbruck University Hospital, Department of Trauma Surgery, Innsbruck (Austria); Mallouhi, Ammar [Innsbruck University Hospital, Department of Radiology II, Innsbruck (Austria)


    Our objective was to evaluate the usefulness of CT virtual preoperative planning in the surgical repositioning of malunited distal radius fracture. Eleven patients with malunited distal radius fracture underwent multislice CT of both wrists. A preoperative workup was performed in a virtual reality environment created from the CT data sets. Virtual planning comprised three main procedures, carrying out the virtual osteotomy of the radius, prediction of the final position of the distal radius after osteotomy and computer-assisted manufacturing of a repositioning device, which was later placed at the surgical osteotomy site to reposition objectively the distal radius fragment before fixation with the osteosynthesis. All patients tolerated the surgical procedure well. During surgery, the orthopedic surgeons were not required in any of the cases to alter the position of the distal radius that was determined by the repositioning device. At postoperative follow-up, the anatomic relationship of the distal radius was restored (radial inclination, 21.4 ; volar tilt, 10.3 ; ulnar variance, 0.5 mm). Clinically, a significant improvement of pronation (P=0.012), supination (P=0.01), flexion (P=0.001) and extension (P=0.006) was achieved. Pain decreased from 54 to 7 points. CT virtual reality is a valuable adjunct for the preoperative workup and surgical reposition of malunited distal radius fractures. (orig.)

  7. Post Traumatic Stress Disorder (PTSD): NIH Research to Results

    ... virtual reality" (VR) exposure therapy. The VR therapy combines traditional therapy and exposure via VR technology that ... families. Read More "Post Traumatic Stress Disorder (PTSD)" Articles PTSD: A Growing Epidemic / Symptoms, Diagnosis, Treatment / NIH ...


    Q. Zhou; Hui-Hai Liu; F.J. Molz; Y. Zhang; G.S. Bodvarsson


    Matrix diffusion is an important mechanism for solute transport in fractured rock. We recently conducted a literature survey on the effective matrix diffusion coefficient, D{sub m}{sup e}, a key parameter for describing matrix diffusion processes at the field scale. Forty field tracer tests at 15 fractured geologic sites were surveyed and selected for the study, based on data availability and quality. Field-scale D{sub m}{sup e} values were calculated, either directly using data reported in the literature or by reanalyzing the corresponding field tracer tests. Surveyed data indicate that the effective-matrix-diffusion-coefficient factor F{sub D} (defined as the ratio of D{sub m}{sup e} to the lab-scale matrix diffusion coefficient [D{sub m}] of the same tracer) is generally larger than one, indicating that the effective matrix diffusion coefficient in the field is comparatively larger than the matrix diffusion coefficient at the rock-core scale. This larger value can be attributed to the many mass-transfer processes at different scales in naturally heterogeneous, fractured rock systems. Furthermore, we observed a moderate trend toward systematic increase in the F{sub D} value with observation scale, indicating that the effective matrix diffusion coefficient is likely to be statistically scale dependent. The F{sub D} value ranges from 1 to 10,000 for observation scales from 5 to 2,000 m. At a given scale, the F{sub D} value varies by two orders of magnitude, reflecting the influence of differing degrees of fractured rock heterogeneity at different sites. In addition, the surveyed data indicate that field-scale longitudinal dispersivity generally increases with observation scale, which is consistent with previous studies. The scale-dependent field-scale matrix diffusion coefficient (and dispersivity) may have significant implications for assessing long-term, large-scale radionuclide and contaminant transport events in fractured rock, both for nuclear waste disposal

  9. Hook plate fixation of acute displaced lateral clavicle fractures: mid-term results and a brief literature overview

    Tiren Davut


    Full Text Available Abstract Background The clavicle hook plate achieves like most other operative techniques, a high percentage of union and a low percentage of complications however concerns about long term complications still exist, particularly the involvement of the acromioclavicular joint. Methods To evaluate the results and long term effects in use of this plate we performed a retrospective analysis with a mean follow up of 65 months (5.4 years of 28 consecutive patients with acute displaced lateral clavicle fractures, treated with the clavicle hook plate. Results Short term functional results in all patients were good to excellent. All but one patient had a united fracture (96%. Nine patients (32% developed impingement symptoms and in 7 patients (25% subacromial osteolysis was found. These findings resolved after plate removal. Twenty-four patients were re-evaluated at a mean follow-up period of 5.4 years. The Constant-Murley score was 97 and the DASH score was 3.5. Four patients (14% developed acromioclavicular joint arthrosis of which one was symptomatic. Three patients (11% had extra articular ossifications of which one was symptomatic. There was no relation between the impingement symptoms, subacromial osteolysis and development of acromioclavicular joint arthrosis or extra articular ossifications. Conclusions The clavicle hook plate is a good primary treatment option for the acute displaced lateral clavicle fracture with few complications. At mid term the results are excellent and no long term complications can be addressed to the use of the plate.

  10. Use of borehole radar reflection logging to monitor steam-enhanced remediation in fractured limestone-results of numerical modelling and a field experiment

    Gregoire, C.; Joesten, P.K.; Lane, J.W.


    Ground penetrating radar is an efficient geophysical method for the detection and location of fractures and fracture zones in electrically resistive rocks. In this study, the use of down-hole (borehole) radar reflection logs to monitor the injection of steam in fractured rocks was tested as part of a field-scale, steam-enhanced remediation pilot study conducted at a fractured limestone quarry contaminated with chlorinated hydrocarbons at the former Loring Air Force Base, Limestone, Maine, USA. In support of the pilot study, borehole radar reflection logs were collected three times (before, during, and near the end of steam injection) using broadband 100 MHz electric dipole antennas. Numerical modelling was performed to predict the effect of heating on radar-frequency electromagnetic (EM) wave velocity, attenuation, and fracture reflectivity. The modelling results indicate that EM wave velocity and attenuation change substantially if heating increases the electrical conductivity of the limestone matrix. Furthermore, the net effect of heat-induced variations in fracture-fluid dielectric properties on average medium velocity is insignificant because the expected total fracture porosity is low. In contrast, changes in fracture fluid electrical conductivity can have a significant effect on EM wave attenuation and fracture reflectivity. Total replacement of water by steam in a fracture decreases fracture reflectivity of a factor of 10 and induces a change in reflected wave polarity. Based on the numerical modelling results, a reflection amplitude analysis method was developed to delineate fractures where steam has displaced water. Radar reflection logs collected during the three acquisition periods were analysed in the frequency domain to determine if steam had replaced water in the fractures (after normalizing the logs to compensate for differences in antenna performance between logging runs). Analysis of the radar reflection logs from a borehole where the temperature

  11. Rap system of stress stimulation can promote bone union after lower tibial bone fracture: a clinical research.

    Yao, Jian-fei; Shen, Jia-zuo; Li, Da-kun; Lin, Da-sheng; Li, Lin; Li, Qiang; Qi, Peng; Lian, Ke-jian; Ding, Zhen-qi


    Lower tibial bone fracture may easily cause bone delayed union or nonunion because of lacking of dynamic mechanical load. Research Group would design a new instrument as Rap System of Stress Stimulation (RSSS) to provide dynamic mechanical load which would promote lower tibial bone union postoperatively. This clinical research was conducted from January 2008 to December 2010, 92 patients(male 61/female 31, age 16-70 years, mean 36.3 years) who suffered lower tibial bone closed fracture were given intramedullary nail fixation and randomly averagely separated into experimental group and control group(according to the successively order when patients went for the admission procedure). Then researchers analysed the clinical healing time, full weight bearing time, VAS (Visual Analogue Scales) score and callus growth score of Lane-Sandhu in 3,6,12 months postoperatively. The delayed union and nonunion rates were compared at 6 and 12 months separately. All the 92 patients had been followed up (mean 14 months). Clinical bone healing time in experimental group was 88.78±8.80 days but control group was 107.91±9.03 days. Full weight bearing time in experimental group was 94.07±9.81 days but control group was 113.24±13.37 days respectively (PRSSS can intermittently provide dynamic mechanical load and stimulate callus formation, promote lower tibial bone union, reduce bone delayed union or nonunion rate. It is an adjuvant therapy for promoting bone union after lower tibial bone fracture.

  12. 髁状突颈部复合型骨折坚强内固定后应力遮挡效应分析%Stress Shielding Analysis of Internal Rigid Fixation of Compound Condylar Fractures

    赵亮; 杨壮群; 虎小易; 陶洪; 陈曦; 刘秀丽; 刘伟


    Objective Try to provide a biomechanical basis for the clinical application of new material via analyzing the stress distribution and the stress shielding effect in different periods when compound fractures of the condylar neck were fixed with different kinds of material. Methods The three-dimensional finite element method was used to analyze the von Mises stress distribution in different periods when the condylar neck compound fractures were fixed with titanium and absorbable miniplates; and then calculated and analyzed stress shielding rates. Results In early stage of fixation, the stress shielding rates provided by two kinds of material were above 95% in the various parts of fracture suture. After the fracture was healed, the stress shielding rates were in the following decreasing order: titanium plate, absorbable plate fixed 1 year, the absorbable plate fixed 3 years. Conclusion There were stress shielding effect during the whole period of fracture healing when mandibular fractures were fixed by titanium miniplate; absorbable plate could provide similar stress shielding effect with titanium plate in early fracture healing stage, and the effect was smaller than that of titanium plate after fracture healing; when focusing on the stress shielding effect, the absorbent material was an ideal internal fixation material.%目的:从生物力学角度分析髁突颈复合型骨折采用不同材料内固定后不同时期骨折局部应力分布状况及应力遮挡作用,试图为新型固定材料的临床应用提供生物力学依据.方法:用三维有限元法分析髁状突颈部复合型骨折采用小型钛板和可吸收板固定后,不同时期骨折局部的yon Mises应力值分布,并且计算比较各时期的应力遮挡率.结果:骨折固定初期,两种材料在各部位的应力遮挡率都在95%以上.骨折愈合后,骨缝各分区的应力遮挡率大小依次为:钛板固定后期>可吸收板固定1年>可吸收板固定3年.结论:下颌

  13. Comparing results from actual and virtual linear scanlines in fractured sandstones of the Marnoso-Arenacea Formation, Northern Apennines, Italy

    Borsani, Angelo; Balsamo, Fabrizio; Bistacchi, Andrea; Ogata, Kei; Storti, Fabrizio; Fetter, Marcos


    Three-dimensional photogrammetric techniques arecommonly used to generate high-resolution digital outcrop models suitable to complement stratigraphic and structural field studies. This is particularly true for near vertical outcrops were direct data collection is very difficult to perform, provided that the data are reliable. To check whether fracture attribute data acquired from photogrammetric digital outcrop models can be effectively integrate field data, we performed a multisource data acquisition programme on the master joint set affecting the Langhian part of the Marnoso Arenacea Formation, a foredeep siliciclastic turbidite succession widely exposed in the external sector of the Northern Apennines. We selected an about 90 m high vertical cliff in a meander of the Santerno River, which was surveyed by both terrestrial and drone-aided photogrammetry to produce two different digital outcrop models of the same strata. Moreover, field data were collected in the same strata along river bed exposures few hundred meters upstream. Comparison of master joint attributes, namely orientation, spacing and height, collected along linear scanlines in the field and in the two digital outcrop models shows quite comparable results, particularly when FSI (Fracture Spacing Index) values are considered. Sensitivity tests of the impact of the number of data on the statistical results from photogrammetric scanlines, where hundreds of measurements can be collected along each scan line, were also performed. Our results provide further support to the effectiveness of the integration between field and photogrammetrically-obtained structural data to study fracture densities in partially accessible exposures. Given the large data numbers that can be collected in digital outcrop models, once validated in the field, photogrammetric data allow robust statistical analysis to be performed on fracture attributes.

  14. Numerical Study on the Permeability of the Hydraulic-Stimulated Fracture Network in Naturally-Fractured Shale Gas Reservoirs

    Zhaobin Zhang


    Full Text Available As hydraulic fracturing is a fluid-rock coupling process, the permeability of the hydraulic-stimulated fracture network in the initial stage has great effects on the propagation of the hydraulic fracture network in the following stages. In this work, the permeability of the hydraulic-stimulated fracture network in shale gas reservoirs is investigated by a newly-proposed model based on the displacement discontinuity method. The permeability of the fracture network relies heavily on fracture apertures, which can be calculated with high precision by the displacement discontinuity method. The hydraulic fracturing processes are simulated based on the natural fracture networks reconstructed from the shale samples in the Longmaxi formation of China. The flow fields are simulated and the permeability is calculated based on the fracture configurations and fracture apertures after hydraulic fracturing treatment. It is found that the anisotropy of the permeability is very strong, and the permeability curves have similar shapes. Therefore, a fitting equation of the permeability curve is given for convenient use in the future. The permeability curves under different fluid pressures and crustal stress directions are obtained. The results show that the permeability anisotropy is stronger when the fluid pressure is higher. Moreover, the permeability anisotropy reaches the minimum value when the maximum principle stress direction is perpendicular to the main natural fracture direction. The investigation on the permeability is useful for answering how the reservoirs are hydraulically stimulated and is useful for predicting the propagation behaviors of the hydraulic fracture network in shale gas reservoirs.

  15. Public priorities for osteoporosis and fracture research: results from a general population survey.

    Paskins, Zoe; Jinks, Clare; Mahmood, Waheed; Jayakumar, Prakash; Sangan, Caroline B; Belcher, John; Gwilym, Stephen


    This is the first national study of public and patient research priorities in osteoporosis and fracture. We have identified new research areas of importance to members of the public, particularly 'access to information from health professionals'. The findings are being incorporated into the research strategy of the National Osteoporosis Society. This study aimed to prioritise, with patients and public members, research topics for the osteoporosis research agenda. An e-survey to identify topics for research was co-designed with patient representatives. A link to the e-survey was disseminated to supporters of the UK National Osteoporosis Society (NOS) in a monthly e-newsletter. Responders were asked to indicate their top priority for research across four topics (understanding and preventing osteoporosis, living with osteoporosis, treating osteoporosis and treating fractures) and their top three items within each topic. Descriptive statistics were used to describe demographics and item ranking. A latent class analysis was applied to identify a substantive number of clusters with different combinations of binary responses. One thousand one hundred eighty-eight (7.4%) respondents completed the e-survey. The top three items overall were 'Having easy access to advice and information from health professionals' (63.8%), 'Understanding further the safety and benefit of osteoporosis drug treatments' (49.9%) and 'Identifying the condition early by screening' (49.2%). Latent class analysis revealed distinct clusters of responses within each topic including primary care management and self-management. Those without a history of prior fracture or aged under 70 were more likely to rate items within the cluster of self-management as important (21.0 vs 12.9 and 19.8 vs 13.3%, respectively). This is the first study of public research priorities in osteoporosis and has identified new research areas of importance to members of the public including access to information. The findings

  16. Pelvic Fractures in Children Results from the German Pelvic Trauma Registry

    Zwingmann, Jörn; Aghayev, Emin; Südkamp, Norbert P;


    ) did not differ statistically. Lethality in the pediatric group was 6.3%, not statistically different from the adults' 4.6%. In all, 18.3% of the pediatric pelvic fractures were treated surgically as compared to 22.7% in the adult group. No child suffered any thrombosis/embolism, acute respiratory...... distress syndrome (ARDS), multiorgan failure (MOF), or neurologic deficit, nor was any septic MOF detected. The differences between adults and children were statistically significant in that the children suffered less frequently from thrombosis/embolism (P = 0.041) and ARDS and MOF (P = 0.006).This...


    Lokesh Chowdary


    Full Text Available Fracture of the distal humerus are complex and challenging injuries to treat. In this study we used d istal humeral posterolateral LCP system, which is an anatomically shaped angular stable system. The purpose of this retrospective study was to evaluate clinical outcome after ORIF with posterolateral LCP plate. METHODS: 24 Consecutive patients with distal humerus fractures treated with posterolateral LCP between October 2010 to December 2014 . 20 patients had complete follow up of 20 months , patients evaluated both clinically & radiologically & VAS & DASH score were used. RESULTS: All patients except 4 r e gained full range of movements , 2 patients lost 5° of extension & 1 patient 10° of extension. No loss of flexion in any patient. One patient had failed fixation who had stated early manual labour.

  18. The nature of fracturing and stress distribution in quartzite around the 1128-M (3700-FT) level of the crescent mine, Coeur d'Alene mining district, Idaho

    Miller, C.H.; Skinner, E.H.


    Silver and copper are the principal ores mined from the quartzite at the Crescent mine. Both the main ore-bearing veins and foliation in the quartzite are parallel to the nearly vertical formational contacts. Anisotropy of the quartzite is indicated by both dynamic and static tests. Disking and breakage of core from holes perpendicular to the foliation are about twice what they are in core from holes parallel to foliation. Natural cleavage as well as slabbing and blasting fractures around the tunnels are also controlled by the foliation. Extensive overcore deformation measurements indicate that most of the influence of the tunnels on the "free" stress field is between the rib and a depth of 2.7 m (1 tunnel diameter). The maximum principal stress axis in the free field is nearly horizontal; its magnitude is not much greater than the vertical component and calculations indicate a nearly hydrostatic free stress field. Stress considerably greater than the free field was measured between about 0.3-2.7 m behind the rib and is caused by a transfer of load from above the tunnel opening. Peak stress is in the vertical direction and about 1.7 m behind the rib. An air-injection survey shows that high permeabilities are confined to the highly fractured annulus around a tunnel to a depth of at least 0.6 m. Air-injection measurements could be taken in the interval of about 0.6-1.8 m, but more fractures with high permeabilities may also be present in the annulus from about 0.6-1.2 m. Permeabilities measured deeper than about 1.8 m by the air-injection technique are either very low or nonexistent. The absence of open and noncontinuous fractures beyond about 1.8 m is also indicated by very low porosities and permeabilities of core, very high stresses (which presumably would close fractures), the lack of stains or secondary fillings in disking fractures, a conspicuous lack of ground water in the tunnels, and the fact that fractures encountered in an experimental 0.9-m tunnel did not

  19. Thoracolumbar spine fractures in the geriatric fracture center : early ambulation leads to good results on short term and is a successful and safe alternative compared to immobilization in elderly patients with two-column vertebral fractures

    Weerink, L B M; Folbert, E C; Kraai, M; Smit, R S; Hegeman, J H; van der Velde, D


    INTRODUCTION: Thoracolumbar spine fractures are common osteoporotic fractures among elderly patients. Several studies suggest that these fractures can be treated successfully with a nonoperative management. The aim of this study is to evaluate the conservative treatment of elderly patients with a ve

  20. Fracture mechanics

    Shannon, John L., Jr.


    The application of fracture mechanics to the design of ceramic structures will require the precise measurement of crack growth and fracture resistance of these materials over their entire range of anticipated service temperatures and standardized test methods for making such measurements. The development of a standard test for measuring the plane strain fracture toughness is sought. Stress intensity factor coefficients were determined for three varieties of chevron-notch specimens, and fracture toughness measurements were made on silicon nitrides, silicon carbides, and aluminum oxides to assess the performance of each specimen variety. It was determined that silicon nitride and silicon carbides have flat crack growth resistance curves, but aluminum oxide does not. Additionally, batch-to-batch differences were noticed for the aluminum oxide. Experiments are continuing to explain the rising crack growth resistance and batch-to-batch variations for the aluminum oxide.

  1. Risk of Stress Fracture Varies by Race/Ethnic Origin in a Cohort Study of 1.3 Million U.S. Army Soldiers.

    Bulathsinhala, Lakmini; Hughes, Julie M; McKinnon, Craig J; Kardouni, Joseph R; Guerriere, Katelyn I; Popp, Kristin L; Matheny, Ronald W; Bouxsein, Mary L


    Stress fractures (SF) are common and costly injuries in military personnel. Risk for SF has been shown to vary with race/ethnicity. Previous studies report increased SF risk in White and Hispanic Soldiers compared to Black soldiers. However, these studies did not account for the large ethnic diversity in the U.S. Military.

  2. [A stress fracture occured by overuse of the other leg to be cause of the Morton neuroma paint: a case report].

    Aytaç, Emrah; Aldemir, Arzu; Comoğlu, Selim Selçuk


    Morton neuroma is a paroxysmal neuralgia form pain usually occurs at the 3rd finger and sole of the foot. The patient mostly suffer from pain while walking. In this report a 40-year-old man with Morton neuroma who has a stress fracture in the other leg because of not using the affected painful foot.

  3. Examination of cracks and fractures on operationally stressed turbine blades; Untersuchung von Rissen und Bruechen an betriebsbeanspruchten Turbinenschaufeln

    Vodopivec, F. [Inst. of Metals and Technologies, Ljubljana (Slovenia); Vrbic, V.S. [Electric Power Work Nikola Tesla, Obrenovac (Yugoslavia); Ule, B. [Inst. of Metals and Technologies, Ljubljana (Slovenia); Zvokelj, J. [Inst. of Metals and Technologies, Ljubljana (Slovenia); Vehovar, L. [Inst. of Metals and Technologies, Ljubljana (Slovenia)


    This paper summarises the results of mechanical and fractographic examinations which had been carried out on fractures on the low-pressure blades of a 300 MW steam turbine. The crack-affected turbine blades had been removed, partly during inspections and partly after turbine breakdowns, in contrast to the fractured blades which had been extracted without exception following turbine breakdowns. (orig.) [Deutsch] Im vorliegenden Beitrag werden die Ergebnisse der mechanischen und fraktographischen Untersuchungen zusammengefasst, die an Bruechen von ND-Schaufeln einer 300-MW-Dampfturbine durchgefuehrt wurden. Die rissbehafteten Turbinenschaufeln wurden teilweise waehrend Revisionen und teilweise nach Turbinenversagen entnommen, im Gegensatz zu den gebrochenen Schaufeln, die ausnahmslos nach Turbinenausfall ausgebaut wurden. (orig.)

  4. Multilayer stress field interference in sandstone and mudstone thin interbed reservoir

    Guo, Jian-Chun; Luo, Bo; Zhu, Hai-Yan; Yuan, Shu-Hang; Deng, Yan; Duan, You-Jing; Duan, Wei-Gang; Chen, Li


    General fracturing and separate layer fracturing play an important role in sandstone and mudstone thin interbed (SMTI) reservoirs, where one of the main issues is to control the excessive height growth of fracturing. The fracture propagation at the interface depends on the induced stress produced by the hydraulic fracturing construction. This paper employed a poroelastic coupled damage element with the cohesive zone method (CZM) to establish a 2D fracture quasi-static propagation model. A parametric study was performed under different fracture height, fracture width, pumping rate, fluid viscosity, in situ stress, elastic modulus and tensile strength with this model. General fracturing and separate layer fracturing are compared with each other through fracture morphology and induced stress. The simulation results show that the absolute value of induced stress increases with the decrease in matrix stress near the fracture tip. As a result, the propagation of the fractures is much easier due to the weakened degree of compression. The growth of fracture height and width, the increase in pumping rate and the excessively large or small value of fluid viscosity lead to larger induced stress on the interface. Higher in situ stress, lower elastic modulus, and higher tensile strength of the interlayers can control the excessive height growth of fracturing. The simulated results also show that the fractures are more likely to be overlapped with each other in general fracturing compared to that in separate-layer fracturing. Results of the simulations suggest that lower pumping rates, the proper value of fluid viscosity, separate layer fracturing and interlayers with higher in situ stress, lower elastic modulus and higher tensile strength tend to limit fracture height. Finally, the proposed model was applied to a practical oil field case to verify its effectiveness.

  5. Development of a Prediction Model for Stress Fracture During an Intensive Physical Training Program: The Royal Marines Commandos

    Sanchez-Santos, Maria T.; Davey, Trish; Leyland, Kirsten M.; Allsopp, Adrian J.; Lanham-New, Susan A.; Judge, Andrew; Arden, Nigel K.; Fallowfield, Joanne L.


    Background: Stress fractures (SFs) are one of the more severe overuse injuries in military training, and therefore, knowledge of potential risk factors is needed to assist in developing mitigating strategies. Purpose: To develop a prediction model for risk of SF in Royal Marines (RM) recruits during an arduous military training program. Study Design: Case-control study; Level of evidence, 3. Methods: RM recruits (N = 1082; age range, 16-33 years) who enrolled between September 2009 and July 2010 were prospectively followed through the 32-week RM training program. SF diagnosis was confirmed from a positive radiograph or magnetic resonance imaging scan. Potential risk factors assessed at week 1 included recruit characteristics, anthropometric assessment, dietary supplement use, lifestyle habits, fitness assessment, blood samples, 25(OH)D, bone strength as measured by heel broadband ultrasound attention, history of physical activity, and previous and current food intake. A logistic least absolute shrinkage and selection operator (LASSO) regression with 10-fold cross-validation was used to select potential predictors among 47 candidate variables. Model performance was assessed using measures of discrimination (c-index) and calibration. Bootstrapping was used for internal validation of the developed model and to quantify optimism. Results: A total of 86 (8%) volunteer recruits presented at least 1 SF during training. Twelve variables were identified as the most important risk factors of SF. Variables strongly associated with SF were age, body weight, pretraining weightbearing exercise, pretraining cycling, and childhood intake of milk and milk products. The c-index for the prediction model, which represents the model performance in future volunteers, was 0.73 (optimism-corrected c-index, 0.68). Although 25(OH)D and VO2max had only a borderline statistically significant association with SF, the inclusion of these factors improved the performance of the model. Conclusion

  6. A Thermoelastic Hydraulic Fracture Design Tool for Geothermal Reservoir Development

    Ahmad Ghassemi


    Geothermal energy is recovered by circulating water through heat exchange areas within a hot rock mass. Geothermal reservoir rock masses generally consist of igneous and metamorphic rocks that have low matrix permeability. Therefore, cracks and fractures play a significant role in extraction of geothermal energy by providing the major pathways for fluid flow and heat exchange. Thus, knowledge of conditions leading to formation of fractures and fracture networks is of paramount importance. Furthermore, in the absence of natural fractures or adequate connectivity, artificial fracture are created in the reservoir using hydraulic fracturing. At times, the practice aims to create a number of parallel fractures connecting a pair of wells. Multiple fractures are preferred because of the large size necessary when using only a single fracture. Although the basic idea is rather simple, hydraulic fracturing is a complex process involving interactions of high pressure fluid injections with a stressed hot rock mass, mechanical interaction of induced fractures with existing natural fractures, and the spatial and temporal variations of in-situ stress. As a result it is necessary to develop tools that can be used to study these interactions as an integral part of a comprehensive approach to geothermal reservoir development, particularly enhanced geothermal systems. In response to this need we have set out to develop advanced thermo-mechanical models for design of artificial fractures and rock fracture research in geothermal reservoirs. These models consider the significant hydraulic and thermo-mechanical processes and their interaction with the in-situ stress state. Wellbore failure and fracture initiation is studied using a model that fully couples poro-mechanical and thermo-mechanical effects. The fracture propagation model is based on a complex variable and regular displacement discontinuity formulations. In the complex variable approach the displacement discontinuities are

  7. Fluid driven fracture mechanics in highly anisotropic shale: a laboratory study with application to hydraulic fracturing

    Gehne, Stephan; Benson, Philip; Koor, Nick; Enfield, Mark


    direction of σ1. Conversely, the crack plane develops perpendicular to the bedding plane, if the bedding plane is orientated normal to σ1. Fracture initiation pressures are higher in the Divider orientation ( 24MPa) than in the Short-Transverse orientation ( 14MPa) showing a tensile strength anisotropy ( 42%) comparable to ambient tensile strength results. We then use X-Ray Computed Tomography (CT) 3D-images to evaluate the evolved fracture network in terms of fracture pattern, aperture and post-test water permeability. For both fracture orientations, very fine, axial fractures evolve over the entire length of the sample. For the fracturing in the Divider orientation, it has been observed, that in some cases, secondary fractures are branching of the main fracture. Test data from fluid driven fracturing experiments suggest that fracture pattern, fracture propagation trajectories and fracturing fluid pressure (initiation and propagation pressure) are predominantly controlled by the interaction between the anisotropic mechanical properties of the shale and the anisotropic stress environment. The orientation of inherent rock anisotropy relative to the principal stress directions seems to be the main control on fracture orientation and required fracturing pressure.

  8. The Behaviour of Fracture Growth in Sedimentary Rocks: A Numerical Study Based on Hydraulic Fracturing Processes

    Lianchong Li


    Full Text Available To capture the hydraulic fractures in heterogeneous and layered rocks, a numerical code that can consider the coupled effects of fluid flow, damage, and stress field in rocks is presented. Based on the characteristics of a typical thin and inter-bedded sedimentary reservoir, China, a series of simulations on the hydraulic fracturing are performed. In the simulations, three points, i.e., (1 confining stresses, representing the effect of in situ stresses, (2 strength of the interfaces, and (3 material properties of the layers on either side of the interface, are crucial in fracturing across interfaces between two adjacent rock layers. Numerical results show that the hydrofracture propagation within a layered sequence of sedimentary rocks is controlled by changing in situ stresses, interface properties, and lithologies. The path of the hydraulic fracture is characterized by numerous deflections, branchings, and terminations. Four types of potential interaction, i.e., penetration, arrest, T-shaped branching, and offset, between a hydrofracture and an interface within the layered rocks are formed. Discontinuous composite fracture segments resulting from out-of-plane growth of fractures provide a less permeable path for fluids, gas, and oil than a continuous planar composite fracture, which are one of the sources of the high treating pressures and reduced fracture volume.

  9. The Shear Mechanisms of Natural Fractures during the Hydraulic Stimulation of Shale Gas Reservoirs

    Zhaobin Zhang


    Full Text Available The shearing of natural fractures is important in the permeability enhancement of shale gas reservoirs during hydraulic fracturing treatment. In this work, the shearing mechanisms of natural fractures are analyzed using a newly proposed numerical model based on the displacement discontinuities method. The fluid-rock coupling system of the model is carefully designed to calculate the shearing of fractures. Both a single fracture and a complex fracture network are used to investigate the shear mechanisms. The investigation based on a single fracture shows that the non-ignorable shearing length of a natural fracture could be formed before the natural fracture is filled by pressurized fluid. Therefore, for the hydraulic fracturing treatment of the naturally fractured shale gas reservoirs, the shear strength of shale is generally more important than the tensile strength. The fluid-rock coupling propagation processes of a complex fracture network are simulated under different crustal stress conditions and the results agree well with those of the single fracture. The propagation processes of complex fracture network show that a smaller crustal stress difference is unfavorable to the shearing of natural fractures, but is favorable to the formation of complex fracture network.

  10. On the fracture of high temperature alloys by creep cavitation under uniaxial or biaxial stress states

    Sanders, John W.; Dadfarnia, Mohsen; Stubbins, James F.; Sofronis, Petros


    It is well known that creep rupture in high temperature alloys is caused by grain boundary cavitation: the nucleation, growth, and coalescence of voids along grain boundaries. However, it has been observed recently that the multiaxial rupture behavior of a promising class of high temperature alloys (Tung et al., 2014) cannot be captured by a well-known empirical creep rupture model due to Hayhurst. In an effort to gain a better understanding of rupture in these materials, we depart from empirical models and simulate the underlying rupture mechanisms directly, employing two related models of void growth from the literature: one due to Sham and Needleman (1983), and an extension of Sham and Needleman's model due to Van der Giessen et al. (1995). Our results suggest that the experimental observations might be explained in terms of the interplay between bulk creep and gain boundary diffusion processes. Furthermore, we find that Sham and Needleman's original void growth model, combined with our rupture model, is well suited to capture the experimental data considered here. Such a mechanism-based understanding of the influence of multiaxial stress states on the creep rupture behavior of high temperature alloys promises to be of value and to provide a basis for the qualification of these alloys for extended service in a variety of elevated temperature applications.

  11. Assessment of foam fracture in sandwich beams using thermoelastic stress analysis

    Dulieu-Barton, J.M.; Berggreen, Christian; Mettemberg, C.


    Thermoelastic Stress Analysis (TSA) has been well established for determining crack-tip parameters in metallic materials. This paper examines its ability to determine accurately the crack-tip parameters for PVC foam used in sandwich structures.......Thermoelastic Stress Analysis (TSA) has been well established for determining crack-tip parameters in metallic materials. This paper examines its ability to determine accurately the crack-tip parameters for PVC foam used in sandwich structures....

  12. Hamate fractures.

    Sarabia Condés, J M; Ibañez Martínez, L; Sánchez Carrasco, M A; Carrillo Julia, F J; Salmerón Martínez, E L


    The purpose of this paper is to present our experience in the treatment of the fractures of the hamate and to make a review of the literature on this topic. We retrospectively reviewed 10 patients treated in our clinic between 2005-2012 suffering from fractures of the hamate. Six cases were fractures of the body and four were fractures of the hamate. Five cases were of associated injuries. Diagnostic delay ranged from 30 days to 2 years. Patient follow-up ranged from 1 to 10 years. Patient satisfaction was evaluated using the DASH questionnaire. Five patients with a fracture of the body underwent surgery, and one was treated conservatively. Two patients with fracture of the hook of the hamate were treated with immobilization, and two more patients had the fragment removed. The grip strength and the digital clip were reduced in 2 cases. Flexion and extension of the wrist was limited in 3 cases. The mobility of the fingers was normal in all the cases, except in one. The results obtained from the DASH questionnaire were normal in all the cases, except in one case of fracture of the hamate, and in two cases of fracture of the body. The surgical treatment should reduce the dislocation and stabilize the injuries with osteosynthesis. The fractures of the hamate are usually diagnosed late, and the most recommended treatment is removal of the fragment, although it cannot be deduced from this study. Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

  13. A fully-coupled geomechanics and flow model for hydraulic fracturing and reservoir engineering applications

    Charoenwongsa, S.; Kazemi, H.; Miskimins, J.; Fakcharoenphol [Colorado School of Mines, Golden, CO (United States)


    A fully coupled geomechanics flow model was used to assess how the changes in pore pressure and temperature influence rock stresses in tight gas reservoirs. The finite difference method was used to develop simulations for phases, components, and thermal stresses. A wave component was used to model the propagation of the strain displacement front as well as changes in stress with time. Fluid and heat flow volumes were modelled separately from rock formation properties. The influence of hydraulic fracturing on stress distributions surrounding the fracture was investigated as well as the effect of filter cake and filtrate. Results of the study showed that significant changes in shear stresses near hydraulic fractures occur as a result of hydraulic fracture face displacement perpendicular to the fracture face. While temperature effects also caused changes in stress distributions, changes in pore pressure did not significantly impact shear stresses as the filtrate did not travel very far into the reservoir. 17 refs., 17 figs.

  14. Finite element analysis of the equivalent stress distribution in Schanz screws during the use of a femoral fracture distractor.

    Giordano, Vincenzo; Godoy-Santos, Alexandre Leme; Belangero, William Dias; Pires, Robinson Esteves Santos; Labronici, Pedro José; Koch, Hilton Augusto


    To evaluate the mechanical stress and elastic deformation exercised in the thread/shaft transition of Schanz screws in assemblies with different screw anchorage distances in the entrance to the bone cortex, through the distribution and location of tension in the samples. An analysis of 3D finite elements was performed to evaluate the distribution of the equivalent stress (triple stress state) in a Schanz screw fixed bicortically and orthogonally to a tubular bone, using two mounting patterns: (1) thread/shaft transition located 20 mm from the anchorage of the Schanz screws in the entrance to the bone cortex and (2) thread/shaft transition located 3 mm from the anchorage of the Schanz screws in entrance to the bone cortex. The simulations were performed maintaining the same direction of loading and the same distance from the force vector in relation to the center of the hypothetical bone. The load applied, its direction, and the distance to the center of the bone were constant during the simulations in order to maintain the moment of flexion equally constant. The present calculations demonstrated linear behavior during the experiment. It was found that the model with a distance of 20 mm between the Schanz screws anchorage in the entrance to the bone cortex and the thread/shaft transition reduces the risk of breakage or fatigue of the material during the application of constant static loads; in this model, the maximum forces observed were higher (350 MPa). The distance between the Schanz screws anchorage at the entrance to the bone cortex and the smooth thread/shaft transition of the screws used in a femoral distractor during acute distraction of a fracture must be farther from the entrance to the bone cortex, allowing greater degree of elastic deformation of the material, lower mechanical stress in the thread/shaft transition, and minimized breakage or fatigue. The suggested distance is 20 mm.

  15. Numerical Simulation of the Propagation of Hydraulic and Natural Fracture Using Dijkstra’s Algorithm

    Yanfang Wu


    Full Text Available Utilization of hydraulic-fracturing technology is dramatically increasing in exploitation of natural gas extraction. However the prediction of the configuration of propagated hydraulic fracture is extremely challenging. This paper presents a numerical method of obtaining the configuration of the propagated hydraulic fracture into discrete natural fracture network system. The method is developed on the basis of weighted fracture which is derived in combination of Dijkstra’s algorithm energy theory and vector method. Numerical results along with experimental data demonstrated that proposed method is capable of predicting the propagated hydraulic fracture configuration reasonably with high computation efficiency. Sensitivity analysis reveals a number of interesting observation results: the shortest path weight value decreases with increasing of fracture density and length, and increases with increasing of the angle between fractures to the maximum principal stress direction. Our method is helpful for evaluating the complexity of the discrete fracture network, to obtain the extension direction of the fracture.

  16. Evaluation of ground-penetrating radar to detect free-phase hydrocarbons in fractured rocks - Results of numerical modeling and physical experiments

    Lane, J.W.; Buursink, M.L.; Haeni, F.P.; Versteeg, R.J.


    The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons in bedrock fractures was evaluated using numerical modeling and physical experiments. The results of one- and two-dimensional numerical modeling at 100 megahertz indicate that GPR reflection amplitudes are relatively insensitive to fracture apertures ranging from 1 to 4 mm. The numerical modeling and physical experiments indicate that differences in the fluids that fill fractures significantly affect the amplitude and the polarity of electromagnetic waves reflected by subhorizontal fractures. Air-filled and hydrocarbon-filled fractures generate low-amplitude reflections that are in-phase with the transmitted pulse. Water-filled fractures create reflections with greater amplitude and opposite polarity than those reflections created by air-filled or hydrocarbon-filled fractures. The results from the numerical modeling and physical experiments demonstrate it is possible to distinguish water-filled fracture reflections from air- or hydrocarbon-filled fracture reflections, nevertheless subsurface heterogeneity, antenna coupling changes, and other sources of noise will likely make it difficult to observe these changes in GPR field data. This indicates that the routine application of common-offset GPR reflection methods for detection of hydrocarbon-filled fractures will be problematic. Ideal cases will require appropriately processed, high-quality GPR data, ground-truth information, and detailed knowledge of subsurface physical properties. Conversely, the sensitivity of GPR methods to changes in subsurface physical properties as demonstrated by the numerical and experimental results suggests the potential of using GPR methods as a monitoring tool. GPR methods may be suited for monitoring pumping and tracer tests, changes in site hydrologic conditions, and remediation activities.The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons

  17. Hip fracture in hospitalized medical patients