Electromyographic investigation of unstable patella before and after its realignment operation

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D D Baksi

2011-01-01

Full Text Available Background: Patellar dislocations are either due to superolateral contracture of the soft tissue or imbalance of the power between the vastus medialis (VM and the vastus lateralis (VL. The imbalance of muscle power as an etiology of patellar dislocation has not been studied. Hence, we studied the recurrent, habitual and permanent dislocations of the patella with an electromyogram (EMG of the vastus medialis, vastus lateralis, and pes anserinus, before and after realignment operations, to document the muscle imbalance and effectiveness of the realignment operation. Materials and Methods: An electromyographic investigation was carried out on the vastus medialis and vastus lateralis in nine recurrent, 20 habitual, and 13 permanent dislocations of the patella, before and after their realignment operations. Pes anserinus transposition, which acted as a medial stabilizer of the patella, was also investigated with an EMG study, to understand its role on patellar stability at 0΀, 30΀, 60΀, 90΀, 120΀, 150΀, and full flexion of the knee. The age of the patients varied from nine to 30 (mean 15 years. There were 24 males and 18 females. Twenty-six patellar dislocations were on the right and 16 were on the left side. Results: Electromyographic pictures reveal subnormal activity of the vastus medialis in all types of dislocations and similar activities of the vastus lateralis in permanent and habitual dislocations recorded pre operatively, which recovered to almost normal values postoperatively, at the mean one-year follow-up. Pes anserinus, which was used for medial stabilization of the patella after its realignment, maintained normal EMG activity before and after the operation. Conclusion: This study is significant for understanding the imbalance of muscle activities in patients with an unstable patella, which can be rectified without recurrence after pes anserinus transposition.

Bilateral recurrent discloation of the patella associated with below knee amputation: A case report

Directory of Open Access Journals (Sweden)

Lenka Prasanna

2005-02-01

Full Text Available Abstract Background Recurrent dislocation of the patella in patients with below knee amputation is a known entity. Abnormally high-riding patella (patella alta and medial patellofemoral ligament insufficiency in these patients predisposes them to patellar instability. The established treatment of this problem is surgical realignment. Case presentation A 25 year old male patient with bilateral below knee amputation presented with bilateral recurrent dislocation of the patella while walking on knees on uneven ground. Clinical and radiographic studies showed patella alta. A simple shoe modification was used to treat this patient. Conclusions A simple shoe modification can be used to treat such a condition which is otherwise treated surgically.

Total knee arthroplasty in a pseudoachondroplastic dwarfism patient with bilateral patellar dislocation.

Science.gov (United States)

Oh, Kwang-Jun; Yoon, Jung-Ro; Yang, Jae-Hyuk

2013-01-01

Late presentation of congenital patellar dislocation with advanced osteoarthritis is rare. This article presents a case of a 59-year-old man with underlying pseudoachondroplastic dwarfism. Advanced osteoarthritis due to bilateral neglected congenital patellar dislocation was treated with total knee arthroplasty without patella relocation surgery. Two years later, the patient had an improvement in Knee Society scores, painless function, and stability. Copyright © 2012 Elsevier B.V. All rights reserved.

High-resolution MRI using a microscopy coil for the diagnosis of recurrent lateral patellar dislocation

International Nuclear Information System (INIS)

Iwata, Yuki; Fujii, Masahiko; Muratsu, Hirotsugu; Kurosaka, Masahiro; Kawamitsu, Hideaki; Sugimura, Kazuro; Shibanuma, Hitoshi

2006-01-01

Magnetic resonance imaging (MRI) has been commonly used for the preoperative evaluation of recurrent lateral patellar dislocation (RLPD). The purpose of this study was to determine the usefulness of high-resolution MRI (HR-MRI) with a microscopy coil for diagnosing RLPD. The study group consisted of 15 patients with clinically diagnosed RLPD and 10 normal volunteers. All studies were performed on a 1.5-T MR system. First, conventional MRIs of the whole knee joint were obtained using the knee coil. Then HR-MRI scans using a microscopy coil in the medial aspect of the patella were obtained at the level of the superior pole of the patella, targeting the medial patellofemoral ligament (MPFL). The acquired HR-MRIs with RLPD were reviewed concerning the MPFL injury and the patellar injury. The MPFL was distinguished as a separate ligament, and the layer structure of the patellar cartilage was visualized clearly in all volunteers. The MPFL injury was visualized in 12 cases (87%); it included discontinuity, thickening, and loosening. The patellar injury was visualized in 11 cases (73%), which included dissecans of the medial margin and cartilage injuries. HR-MRI with a microscopy coil provides precise information of the MPFL and patellar cartilage injury for the diagnosis of RLPD. (author)

[New varieties of lateral metatarsophalangeal dislocations of the great toe].

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Bousselmame, N; Rachid, K; Lazrak, K; Galuia, F; Taobane, H; Moulay, I

2001-04-01

We report seven cases of traumatic dislocation of the great toe, detailing the anatomy, the mechanism of injury and the radiographic diagnosis. We propose an additional classification based on three hereto unreported cases. Between october 1994 and october 1997, we treated seven patients with traumatic dislocation of the first metatarso-phalangeal joint of the great toe. There were six men and one woman, mean age 35 years (range 24 - 44 years). Dislocation was caused by motor vehicle accidents in four cases and by falls in three. Diagnosis was made on anteroposterior, lateral and medial oblique radiographs. According to Jahss' classification, there was one type I and three type IIB dislocations. There was also one open lateral dislocation and two dorsomedial dislocations. Only these dorsomedial dislocations required open reduction, done via a dorsal approach. Mean follow-up was 17.5 months (range 9 - 24 months) in six cases. One patient was lost to follow-up. The outcome was good in six cases and poor in one (dorsomedial dislocation). Dislocation of the first metatarso-phalangeal joint of the great toe is an uncommon injury. In 1980, Jahss reported two cases and reviewed three others described in the literature. He proposed three types of dislocation based on the feasibility of closed reduction (type I, II and IIB). In 1991, Copeland and Kanat reported a unique case in which there was an association of IIA and IIB lesions. They proposed an addition to the classification (type IIC). In 1994, Garcia Mata et al. reported another case which had not been described by Jahss and proposed another addition. All dislocations reported to date have been sagittal dislocations. Pathological alteration of the collateral ligaments has not been previously reported. In our experience, we have seen one case of open lateral dislocation due, at surgical exploration, to medial ligament rupture and two cases of dorsomedial dislocation due, at surgical exploration, to lateral ligament

A radiological study of the patella and the cartilage of patella by computed tomography following double-contrast arthrography

International Nuclear Information System (INIS)

Kim, Myung Joon; Yang, Seoung Oh

1987-01-01

Recurrent subluxation or dislocation of the patella is a painful condition that frequently leads to chondromalacia or arthrosis of the patellofemoral joint. A radiographic evaluation of the patella and patella cartilage is important in the diagnosis of chondromalacia and mal alignment. Authors performed the patellofemoral joint CT following the double contrast arthrography in 53 patients with knee joint pains who had visited to Capital Armed Forces General Hospital from July to December, 1986. Authors analysed the shape and position of patella and the shape of patella cartilage. The results were as follows; 1. shape of patella:The most common types are type II/III (14 cases) and type III (14 cases). type III → IV-9 cases, type I-5 cases, type IV-5 cases, other type-4 cases, type II-2 cases, no type V. 2. position of patella:Only 2 cases showed subluxation and external rotation of patella. 3. shape of patella cartilage:a)congruous cartilage-21 cases (39.6%) b)regular cartilage-22 cases (41.5%) c)irregular cartilage-10 cases (18.9%) irregular imbibition of contrast media-7 cases localized loss of cartilage or erosion-2 cases thinning of cartilage-1 case 4. Fissure and erosions of cartilages in 3 cases were confirmed by operation and knee arthroscopy

A radiological study of the patella and the cartilage of patella by computed tomography following double-contrast arthrography

Energy Technology Data Exchange (ETDEWEB)

Kim, Myung Joon; Yang, Seoung Oh [Capital Armed Forces General Hospital, Seoul (Korea, Republic of)

1987-04-15

Recurrent subluxation or dislocation of the patella is a painful condition that frequently leads to chondromalacia or arthrosis of the patellofemoral joint. A radiographic evaluation of the patella and patella cartilage is important in the diagnosis of chondromalacia and mal alignment. Authors performed the patellofemoral joint CT following the double contrast arthrography in 53 patients with knee joint pains who had visited to Capital Armed Forces General Hospital from July to December, 1986. Authors analysed the shape and position of patella and the shape of patella cartilage. The results were as follows; 1. shape of patella:The most common types are type II/III (14 cases) and type III (14 cases). type III {yields} IV-9 cases, type I-5 cases, type IV-5 cases, other type-4 cases, type II-2 cases, no type V. 2. position of patella:Only 2 cases showed subluxation and external rotation of patella. 3. shape of patella cartilage:a)congruous cartilage-21 cases (39.6%) b)regular cartilage-22 cases (41.5%) c)irregular cartilage-10 cases (18.9%) irregular imbibition of contrast media-7 cases localized loss of cartilage or erosion-2 cases thinning of cartilage-1 case 4. Fissure and erosions of cartilages in 3 cases were confirmed by operation and knee arthroscopy.

Orthopaedic measurements with computed radiography: Methodological development, accuracy, and radiation dose with special reference to the weight-bearing lower extremity and the dislocating patella

International Nuclear Information System (INIS)

Sanfridsson, J.

2001-01-01

The overall aim of this study was to develop and evaluate a measurement system for computed radiography and Picture Archiving and Communication Systems, permitting measurements of long distances and angles in and between related images. The developed measurement system, which was based on the QUESTOR Precision Radiography system, was applied to the weight-bearing knee with special reference to the dislocating patella. The QPR system modified for CR fulfilled the criteria for measuring the weight-bearing knee. The special measuring assistance tools that were developed were important for the implementation of CR and PACS, particularly in workstations programmed for musculoskeletal radiology. The energy imparted to the patient was reduced by 98% at the lowest exposure of the CR-system, compared with our conventional analogue method, without loss of diagnostic accuracy. The CR technique creates a possibility, to an extent not previously feasible, to differentiate the exposure parameters (and thus minimise the radiation dose to the patient) by carefully considering the purpose of the examination. A radiographic method for measuring the rotation of the femur and the tibia, and the patellar translation was developed and applied to healthy volunteers. The introduced patellar variables have yielded new insights into the complex sequence of motions between the femur, tibia, and patella. The patients with a dislocating patella were subdivided into one 'clean' group of spontaneous dislocations and one group with various traumas in the history, which thus resulted in two groups with distinct radiographic differences. The Q-angle was decreased in knees that had suffered dislocations, and the traditional surgical treatment with a further reduction of the Q-angle must be challenged. The use of clinical measurements of the Q-angle was not an optimal way to evaluate the mechanical alignment in the patellofemoral joint under physiological conditions. In this study, we have proved

Orthopaedic measurements with computed radiography: Methodological development, accuracy, and radiation dose with special reference to the weight-bearing lower extremity and the dislocating patella

Energy Technology Data Exchange (ETDEWEB)

Sanfridsson, J. [Univ. Hospital, Lund (Sweden). Dept. of Diagnostic Radiology

2001-03-01

The overall aim of this study was to develop and evaluate a measurement system for computed radiography and Picture Archiving and Communication Systems, permitting measurements of long distances and angles in and between related images. The developed measurement system, which was based on the QUESTOR Precision Radiography system, was applied to the weight-bearing knee with special reference to the dislocating patella. The QPR system modified for CR fulfilled the criteria for measuring the weight-bearing knee. The special measuring assistance tools that were developed were important for the implementation of CR and PACS, particularly in workstations programmed for musculoskeletal radiology. The energy imparted to the patient was reduced by 98% at the lowest exposure of the CR-system, compared with our conventional analogue method, without loss of diagnostic accuracy. The CR technique creates a possibility, to an extent not previously feasible, to differentiate the exposure parameters (and thus minimise the radiation dose to the patient) by carefully considering the purpose of the examination. A radiographic method for measuring the rotation of the femur and the tibia, and the patellar translation was developed and applied to healthy volunteers. The introduced patellar variables have yielded new insights into the complex sequence of motions between the femur, tibia, and patella. The patients with a dislocating patella were subdivided into one 'clean' group of spontaneous dislocations and one group with various traumas in the history, which thus resulted in two groups with distinct radiographic differences. The Q-angle was decreased in knees that had suffered dislocations, and the traditional surgical treatment with a further reduction of the Q-angle must be challenged. The use of clinical measurements of the Q-angle was not an optimal way to evaluate the mechanical alignment in the patellofemoral joint under physiological conditions. In this study, we have

Case report 539: Tophaceous gout of the patella

International Nuclear Information System (INIS)

Walot, I.; Staple, T.W.

1989-01-01

Anteroposterior, lateral, and skyline radiographs of a man's left knee and patella showed extensive destructive changes in the lateral half of the patella and a partially calcified adjacent soft tissue mass. The articular cartillages were moderately calcified, but the cartilage space was normal. A joint effusion was present. The diagnosis is: Tophaceous gout of the patella. (orig./GDG)

Normal blood supply of the canine patella

International Nuclear Information System (INIS)

Howard, P.E.; Wilson, J.W.; Robbins, T.A.; Ribble, G.A.

1986-01-01

The normal blood supply of the canine patella was evaluated, using microangiography and correlated histology. Arterioles entered the cortex of the patella at multiple sites along the medial, lateral, and dorsal aspects. The body of the patella was vascularized uniformly, with many arterioles that branched and anastomosed extensively throughout the patella. The patella was not dependent on a single nutrient artery for its afferent supply, but had an extensive interior vascular network. These factors should ensure rapid revascularization and healing of patellar fractures, provided appropriate fracture fixation is achieved

Bone bruise in acute traumatic patellar dislocation: volumetric magnetic resonance imaging analysis with follow-up mean of 12 months

International Nuclear Information System (INIS)

Paakkala, Antti; Paakkala, Timo; Sillanpaeae, Petri; Maeenpaeae, Heikki; Huhtala, Heini

2010-01-01

The aim of the study was to assess volumetric analysis of bone bruises in acute primary traumatic patellar dislocation by magnetic resonance imaging (MRI) and resolving resolution of bruises in follow-up MRI. MRI was performed in 23 cases. A follow-up examination was done at a mean of 12 months after dislocation. Volumes of patellar and femur bruises for every patient were evaluated separately by two musculoskeletal radiologists, and mean values of the bruises were assessed. Other MRI findings were evaluated, together with agreement by consensus. Bone bruise volumes were compared with other MR findings. In the acute study 100% of patients showed bruising of the lateral femoral condyle and 96% bruising of the patella. The bruise was located at the medial femoral condyle in 30% and at the patellar median ridge in 74% of patients. The median volume of the femoral bruise was 25,831 mm 3 and of the patellar bruise 2,832 mm 3 . At the follow-up study 22% of patients showed bruising of the lateral femoral condyle and 39% bruising of the patella, the median volumes of the bruises being 5,062 mm 3 and 1,380 mm 3 , respectively. Larger patellar bruise volume correlated with larger femur bruise volume in the acute (r=0.389, P=0.074) and the follow-up (r=1.000, P<0.01) studies. Other MRI findings did not correlate significantly with bone bruise volumes. Bone bruising is the commonest finding in cases of acute patellar dislocation, being seen even 1 year after trauma and indicating significant bone trabecular injury in the patellofemoral joint. A large bruise volume may be associated with subsequent chondral lesion progression at the patella. We concluded that the measurement of bone bruise volume in patients with acute patellar dislocation is a reproducible method but requires further studies to evaluate its clinical use. (orig.)

Lateral subtalar dislocation : Case report and review of the literature

NARCIS (Netherlands)

Veltman, Ewout S; Steller, Ernst Ja; Wittich, Philippe; Keizer, Jort

2016-01-01

A case of complicated lateral subtalar dislocation is presented and the literature concerning this injury is reviewed. Subtalar joint dislocations are rare and often the result of a high-energy trauma. Complications include avascular necrosis of the talus, infection, posttraumatic osteoarthritis

Irreducible lateral dislocation of the elbow.

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Chhaparwal M

1997-01-01

Full Text Available A rare case of an irreducible post-traumatic lateral dislocation of elbow is presented. The mechanism of injury was fall on a flexed elbow with trauma on its medial aspect resulting in pronation of the forearm. At open reduction, the brachialis muscle was in the form of a tight band which prevented reduction. The ulnar nerve was entrapped in the joint.

[Significance of lateral release in the therapy of patellar chondromalacia].

Science.gov (United States)

Krüger, T; Göbel, F; Huschenbett, A; Hein, W

2002-10-01

A retrospective study was performed in 26 patients who underwent an operation for femoro-patellar pain due to a patellar chondromalacia with or without minor patellar dislocation/lateral pressure syndrome. The average age of the patients was 28.5 (15-39) years. 22 of the 26 patients revealed minor chondral damages of the stages 1 and 2 according to Outerbridge. In 12 patients ("lavage" group), an arthroscopic joint debridement only was carried out, while an additional open, lateral retinaculum release was made in 14 patients ("lateral release" group). The patella's distance of dislocation according to Hepp was reduced on an average of 3.0 (0-7) mm (p = 0.0019). The results of Bentley's score obtained during the follow-up interval on an average of 30.1 (9 to 60) months were almost identical for both groups. "Good" and "very good" results were achieved in the "lavage" group (83.3 %) and "lateral release" group (78.6 % of the patients). Lateral release should be used in cases of patellar decentration between 5 and 10 mm and adequate pain symptoms. The post-operative distance of dislocation should be less than 5 mm. Under such conditions and with minor chondral damage, a combined approach by using an arthroscopic joint debridement and open lateral release is promising to treat a patellar dislocation/lateral pressure syndrome.

Bone bruise in acute traumatic patellar dislocation: volumetric magnetic resonance imaging analysis with follow-up mean of 12 months

Energy Technology Data Exchange (ETDEWEB)

Paakkala, Antti; Paakkala, Timo [Tampere University Hospital, Department of Radiology, Tampere (Finland); Sillanpaeae, Petri; Maeenpaeae, Heikki [Tampere University Hospital, Department of Orthopaedics and Traumatology, Tampere (Finland); Huhtala, Heini [University of Tampere, School of Public Health, Tampere (Finland)

2010-07-15

The aim of the study was to assess volumetric analysis of bone bruises in acute primary traumatic patellar dislocation by magnetic resonance imaging (MRI) and resolving resolution of bruises in follow-up MRI. MRI was performed in 23 cases. A follow-up examination was done at a mean of 12 months after dislocation. Volumes of patellar and femur bruises for every patient were evaluated separately by two musculoskeletal radiologists, and mean values of the bruises were assessed. Other MRI findings were evaluated, together with agreement by consensus. Bone bruise volumes were compared with other MR findings. In the acute study 100% of patients showed bruising of the lateral femoral condyle and 96% bruising of the patella. The bruise was located at the medial femoral condyle in 30% and at the patellar median ridge in 74% of patients. The median volume of the femoral bruise was 25,831 mm{sup 3} and of the patellar bruise 2,832 mm{sup 3}. At the follow-up study 22% of patients showed bruising of the lateral femoral condyle and 39% bruising of the patella, the median volumes of the bruises being 5,062 mm{sup 3} and 1,380 mm{sup 3}, respectively. Larger patellar bruise volume correlated with larger femur bruise volume in the acute (r=0.389, P=0.074) and the follow-up (r=1.000, P<0.01) studies. Other MRI findings did not correlate significantly with bone bruise volumes. Bone bruising is the commonest finding in cases of acute patellar dislocation, being seen even 1 year after trauma and indicating significant bone trabecular injury in the patellofemoral joint. A large bruise volume may be associated with subsequent chondral lesion progression at the patella. We concluded that the measurement of bone bruise volume in patients with acute patellar dislocation is a reproducible method but requires further studies to evaluate its clinical use. (orig.)

Imaging assessment of patellar instability and its treatment in children and adolescents

Energy Technology Data Exchange (ETDEWEB)

Meyers, Arthur B.; Sharafinski, Mark [Children' s Hospital of Wisconsin, Medical College of Wisconsin, Department of Radiology, P.O. Box 1997, Milwaukee, WI (United States); Laor, Tal; Zbojniewicz, Andrew M. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States)

2016-05-15

Transient patellar dislocation is a common entity in children and adolescents, characterized by lateral dislocation of the patella, usually with spontaneous reduction. Many predisposing conditions have been described, including trochlear dysplasia, excessive lateral patellar tilt, patella alta and lateralization of the tibial tuberosity. Associated injuries are bone bruises of the patella and lateral femoral condyle, tears of the medial retinaculum that include the medial patellofemoral ligament (MPFL), tears of the vastus medialis obliquus muscle, injuries of articular cartilage, and intra-articular bodies. Children who are refractory to conservative management, have a large cartilage defect, or are at substantial risk for recurrent dislocations are candidates for surgical procedures to prevent future dislocations. Procedures can include MPFL repair or reconstruction, tibial tubercle repositioning and lateral retinacular release. The purpose of this review is to illustrate the imaging findings of transient patellar dislocation in the acute setting, the normal imaging appearance after surgical intervention, and post-surgical complications. (orig.)

Imaging assessment of patellar instability and its treatment in children and adolescents

International Nuclear Information System (INIS)

Meyers, Arthur B.; Sharafinski, Mark; Laor, Tal; Zbojniewicz, Andrew M.

2016-01-01

Transient patellar dislocation is a common entity in children and adolescents, characterized by lateral dislocation of the patella, usually with spontaneous reduction. Many predisposing conditions have been described, including trochlear dysplasia, excessive lateral patellar tilt, patella alta and lateralization of the tibial tuberosity. Associated injuries are bone bruises of the patella and lateral femoral condyle, tears of the medial retinaculum that include the medial patellofemoral ligament (MPFL), tears of the vastus medialis obliquus muscle, injuries of articular cartilage, and intra-articular bodies. Children who are refractory to conservative management, have a large cartilage defect, or are at substantial risk for recurrent dislocations are candidates for surgical procedures to prevent future dislocations. Procedures can include MPFL repair or reconstruction, tibial tubercle repositioning and lateral retinacular release. The purpose of this review is to illustrate the imaging findings of transient patellar dislocation in the acute setting, the normal imaging appearance after surgical intervention, and post-surgical complications. (orig.)

Radiologic evaluation of chondromalacia patellae

International Nuclear Information System (INIS)

Lund, F.; Nilsson, B.E

1980-01-01

In a series of patients in whom the patello-femoral joint has been examined by arthroscopy, in conjunction with arthrotomy or both, previously obtained films were reviewed. A series of radiologic morphometric measurements with bearing on the shape of the patella and the patello-femoral joint was carried out and compared between patients who had normal patello-femoral joints, patients with chondromalacia grade II or III and patients with chondromalacia grade IV or arthrosis. No difference between the three groups in any of the variables was found. However, a shallow excavation in the subchondral bone was observed in the lateral view of the patella in most of those patients with proven chondromalacia patellae. (Auth.)

Finite Element Analysis of Patella Alta: A Patellofemoral Instability Model.

Science.gov (United States)

Watson, Nicole A; Duchman, Kyle R; Grosland, Nicole M; Bollier, Matthew J

2017-01-01

This study aims to provide biomechanical data on the effect of patella height in the setting of medial patellofemoral ligament (MPFL) reconstruction using finite element analysis. The study will also examine patellofemoral joint biomechanics using variable femoral insertion sites for MPFL reconstruction. A previously validated finite element knee model was modified to study patella alta and baja by translating the patella a given distance to achieve each patella height ratio. Additionally, the models were modified to study various femoral insertion sites of the MPFL (anatomic, anterior, proximal, and distal) for each patella height model, resulting in 32 unique scenarios available for investigation. In the setting of patella alta, the patellofemoral contact area decreased, resulting in a subsequent increase in maximum patellofemoral contact pressures as compared to the scenarios with normal patellar height. Additionally, patella alta resulted in decreased lateral restraining forces in the native knee scenario as well as following MPFL reconstruction. Changing femoral insertion sites had a variable effect on patellofemoral contact pressures; however, distal and anterior femoral tunnel malpositioning in the setting of patella alta resulted in grossly elevated maximum patellofemoral contact pressures as compared to other scenarios. Patella alta after MPFL reconstruction results in decreased lateral restraining forces and patellofemoral contact area and increased maximum patellofemoral contact pressures. When the femoral MPFL tunnel is malpositioned anteriorly or distally on the femur, the maximum patellofemoral contact pressures increase with severity of patella alta. When evaluating patients with patellofemoral instability, it is important to recognize patella alta as a potential aggravating factor. Failure to address patella alta in the setting of MPFL femoral tunnel malposition may result in even further increases in patellofemoral contact pressures, making it

Complications of Fracture and Dislocation Treatment By Traditional ...

African Journals Online (AJOL)

Alasia Datonye

TBS treatment of fractures and dislocations at a private ... gangrene, delayed union and pressure ulcer. The most frequent ... common complications include non-union, malunion .... nonunions in the patella and 2 nonunions in the ankle. The.

The associations between indices of patellofemoral geometry and knee pain and patella cartilage volume: a cross-sectional study

Directory of Open Access Journals (Sweden)

Urquhart Donna M

2010-05-01

Full Text Available Abstract Background Whilst patellofemoral pain is one of the most common musculoskeletal disorders presenting to orthopaedic clinics, sports clinics, and general practices, factors contributing to its development in the absence of a defined arthropathy, such as osteoarthritis (OA, are unclear. The aim of this cross-sectional study was to describe the relationships between parameters of patellofemoral geometry (patella inclination, sulcus angle and patella height and knee pain and patella cartilage volume. Methods 240 community-based adults aged 25-60 years were recruited to take part in a study of obesity and musculoskeletal health. Magnetic resonance imaging (MRI of the dominant knee was used to determine the lateral condyle-patella angle, sulcus angle, and Insall-Salvati ratio, as well as patella cartilage and bone volumes. Pain was assessed by the Western Ontario and McMaster University Osteoarthritis Index (WOMAC VA pain subscale. Results Increased lateral condyle-patella angle (increased medial patella inclination was associated with a reduction in WOMAC pain score (Regression coefficient -1.57, 95% CI -3.05, -0.09 and increased medial patella cartilage volume (Regression coefficient 51.38 mm3, 95% CI 1.68, 101.08 mm3. Higher riding patella as indicated by increased Insall-Salvati ratio was associated with decreased medial patella cartilage volume (Regression coefficient -3187 mm3, 95% CI -5510, -864 mm3. There was a trend for increased lateral patella cartilage volume associated with increased (shallower sulcus angle (Regression coefficient 43.27 mm3, 95% CI -2.43, 88.98 mm3. Conclusion These results suggest both symptomatic and structural benefits associated with a more medially inclined patella while a high-riding patella may be detrimental to patella cartilage. This provides additional theoretical support for the current use of corrective strategies for patella malalignment that are aimed at medial patella translation, although

The associations between indices of patellofemoral geometry and knee pain and patella cartilage volume: a cross-sectional study.

Science.gov (United States)

Tanamas, Stephanie K; Teichtahl, Andrew J; Wluka, Anita E; Wang, Yuanyuan; Davies-Tuck, Miranda; Urquhart, Donna M; Jones, Graeme; Cicuttini, Flavia M

2010-05-10

Whilst patellofemoral pain is one of the most common musculoskeletal disorders presenting to orthopaedic clinics, sports clinics, and general practices, factors contributing to its development in the absence of a defined arthropathy, such as osteoarthritis (OA), are unclear.The aim of this cross-sectional study was to describe the relationships between parameters of patellofemoral geometry (patella inclination, sulcus angle and patella height) and knee pain and patella cartilage volume. 240 community-based adults aged 25-60 years were recruited to take part in a study of obesity and musculoskeletal health. Magnetic resonance imaging (MRI) of the dominant knee was used to determine the lateral condyle-patella angle, sulcus angle, and Insall-Salvati ratio, as well as patella cartilage and bone volumes. Pain was assessed by the Western Ontario and McMaster University Osteoarthritis Index (WOMAC) VA pain subscale. Increased lateral condyle-patella angle (increased medial patella inclination) was associated with a reduction in WOMAC pain score (Regression coefficient -1.57, 95% CI -3.05, -0.09) and increased medial patella cartilage volume (Regression coefficient 51.38 mm3, 95% CI 1.68, 101.08 mm3). Higher riding patella as indicated by increased Insall-Salvati ratio was associated with decreased medial patella cartilage volume (Regression coefficient -3187 mm3, 95% CI -5510, -864 mm3). There was a trend for increased lateral patella cartilage volume associated with increased (shallower) sulcus angle (Regression coefficient 43.27 mm3, 95% CI -2.43, 88.98 mm3). These results suggest both symptomatic and structural benefits associated with a more medially inclined patella while a high-riding patella may be detrimental to patella cartilage. This provides additional theoretical support for the current use of corrective strategies for patella malalignment that are aimed at medial patella translation, although longitudinal studies will be needed to further substantiate this.

How reliable is MRI in diagnosing cartilaginous lesions in patients with first and recurrent lateral patellar dislocations?

Directory of Open Access Journals (Sweden)

Haage Patrick

2010-07-01

Full Text Available Abstract Background Lateral dislocation of the patella (LPD leads to cartilaginous injuries, which have been reported to be associated with retropatellar complaints and the development of patellofemoral osteoarthritis. Therefore, the purpose of this study was to determine the reliability of MRI for cartilage diagnostics after a first and recurrent LPD. Methods After an average of 4.7 days following an acute LPD, 40 patients (21 with first LPDs and 19 with recurrent LPDs underwent standardized 1.5 Tesla MRI (sagittal T1-TSE, coronal STIR-TSE, transversal fat-suppressed PD-TSE, sagittal fat-suppressed PD-TSE. MRI grading was compared to arthroscopic assessment of the cartilage. Results Sensitivities and positive predictive values for grade 3 and 4 lesions were markedly higher in the patient group with first LPDs compared to the group with recurrent LPDs. Similarly, intra- and inter-observer agreement yielded higher kappa values in patients with first LPDs compared to those with recurrent LPDs. All grade 4 lesions affecting the subchondral bone (osteochondral defects, such as a fissuring or erosion, were correctly assessed on MRI. Conclusions This study demonstrated a comparatively good diagnostic performance for MRI in the evaluation of first and recurrent LPDs, and we therefore recommend MRI for the cartilage assessment after a LPD.

Association between trochlear morphology and chondromalacia patella: an MRI study.

Science.gov (United States)

Duran, Semra; Cavusoglu, Mehtap; Kocadal, Onur; Sakman, Bulent

This study aimed to compare trochlear morphology seen in magnetic resonance imaging between patients with chondromalacia patella and age-matched control patients without cartilage lesion. Trochlear morphology was evaluated using the lateral trochlear inclination, medial trochlear inclination, sulcus angle and trochlear angle on the axial magnetic resonance images. Consequently, an association between abnormal trochlear morphology and chondromalacia patella was identified in women. In particular, women with flattened lateral trochlea are at an increased risk of patellar cartilage structural damage. Copyright © 2016 Elsevier Inc. All rights reserved.

Epitaxial lateral overgrowth - a tool for dislocation blockade in multilayer system

International Nuclear Information System (INIS)

Zytkiewicz, Z.R.

1998-01-01

Results on epitaxial lateral overgrowth of GaAs layers are reported. The methods of controlling the growth anisotropy, the effect of substrate defects filtration in epitaxial lateral overgrowth procedure and influence of the mask on properties of epitaxial lateral overgrowth layers will be discussed. The case od GaAs epitaxial lateral overgrowth layers grown by liquid phase epitaxy on heavily dislocated GaAs substrates was chosen as an example to illustrate the processes discussed. The similarities between our results and those reported recently for GaN layers grown laterally by metalorganic vapour phase epitaxy will be underlined. (author)

MRI quantitative morphologic analysis of patellofemoral region: lack of correlation with chondromalacia patellae at surgery.

Science.gov (United States)

Endo, Yoshimi; Schweitzer, Mark E; Bordalo-Rodrigues, Marcelo; Rokito, Andrew S; Babb, James S

2007-11-01

In numerous studies, the morphologic features of the patellofemoral joint have been analyzed on radiographs. The objective of this study was to assess patellofemoral measurements on MR images and to correlate the measurements with the presence or absence of chondromalacia patellae confirmed at surgery. Axial and sagittal MR images of 98 knees (97 patients) were evaluated. Lateral and medial patellar facet lengths, lateral-to-medial facet length ratio, and interfacet angle were measured at three levels through the patella. Trochlear depth was measured on an axial slice. Patella and patellar tendon lengths, patellar tendon-to-patella ratio, and overlap of the patellar and trochlear articular cartilages were measured on sagittal slices. These measurements in knees with chondromalacia patellae were compared with those in knees without chondromalacia patellae. For assessment of reproducibility, axial measurements were repeated by a second observer. There was no statistically significant difference in any of the axial and sagittal slice measurements between knees with and those without chondromalacia patellae. Interobserver reliability was excellent for measurements of trochlear depth and measurements in the superior and middle aspects of the patella. Measurements through the inferior patella were slightly less reproducible. The results of our study with MRI confirmed many previous radiographic findings. Although we did not find correlation between the presence of chondromalacia patellae and the patellofemoral indexes we analyzed, it is possible that the results of further investigations incorporating different grades of chondromalacia and different locations along the patellar articular surface may lead to further insight regarding the morphologic risk factors for chondromalacia patellae.

Short-term results of medial patellofemoral ligament reconstruction for patellar dislocation

International Nuclear Information System (INIS)

Sakuraba, Koji; Miura, Hiromasa; Matsuda, Shuichi; Okazaki, Ken; Iwamoto, Yukihide; Fukuoka, Shinji

2009-01-01

The short-term results of medial patellofemoral ligament (MPFL) reconstruction were reviewed. MPFL reconstruction surgery was performed on 13 patients (13 knees, three male, five female, mean age 24.1 years) with recurrent and habitual dislocation of the patella. After average 18.5 month follow-up, there has been no recurrence of dislocation and limitation of range of motion except for one case. The mean Kujula score was 60±20.2 preoperatively and 91±15 postoperatively. According to the Crosby and Insall grading system, six ceses were excellent, six cases were good, and one case was fair to poor. On axial radiographs, the mean congruence angle was 31.3±21.4deg preoperatively and -3.65±20.72deg postoperatively. The mean tilting angle was 32.1±7.9deg preoperatively and 21.9±8.39deg postoperatively. The mean lateral shift was 41.6±9.7% preoperatively and 24.5±9.9% postoperatively. These results demonstrate the short-term effectiveness of MPFL reconstruction. (author)

Osteoarthritis of the patella, lateral femoral condyle and posterior medial femoral condyle correlate with range of motion.

Science.gov (United States)

Suzuki, Takashi; Motojima, Sayaka; Saito, Shu; Ishii, Takao; Ryu, Keinosuke; Ryu, Junnosuke; Tokuhashi, Yasuaki

2013-11-01

The type of osteoarthritis and the degree of severity which causes restriction of knee range of motion (ROM) is still largely unknown. The objective of this study was to analyse the location and the degree of cartilage degeneration that affect knee range of motion and the connection, if any, between femorotibial angle (FTA) and knee ROM restriction. Four hundreds and fifty-six knees in 230 subjects with knee osteoarthritis undergoing knee arthroplasty were included. Articular surface was divided into eight sections, and cartilage degeneration was evaluated macroscopically during the operation. Cartilage degeneration was classified into four grades based on the degree of exposure of subchondral bone. A Pearson correlation was conducted between FTA and knee flexion angle to determine whether high a degree of FTA caused knee flexion restriction. A logistic regression analysis was also conducted to detect the locations and levels of cartilage degeneration causing knee flexion restriction. No correlation was found between FTA and flexion angle (r = -0.08). Flexion angle was not restricted with increasing FTA. Logistic regression analysis showed significant correlation between restricted knee ROM and levels of knee cartilage degeneration in the patella (odds ratio (OR) = 1.77; P = 0.01), the lateral femoral condyle (OR = 1.62; P = 0.03) and the posterior medial femoral condyle (OR = 1.80; P = 0.03). For clinical relevance, soft tissue release and osteophyte resection around the patella, lateral femoral condyle and posterior medial femoral condyle might be indicated to obtain a higher degree of knee flexion angle.

A hypoplastic patella fracture in nail patella syndrome: a case report

LENUS (Irish Health Repository)

Neill, Shane C O

2012-07-16

AbstractIntroductionNail patella syndrome is a rare autosomal dominant hereditary condition, with an incidence of 22 per million in the United Kingdom. The syndrome’s most common features include iliac horns, hypoplastic patella and nail dysplasia.Case presentationWe report the case of a 26-year-old Caucasian man with nail patella syndrome who sustained a fracture of his right hypoplastic patella after a fall. His right knee became swollen and he was unable to extend against gravity immediately post fall. Radiographs revealed a fracture of the lower pole of his right patella with associated complete disruption of the extensor mechanism of the knee. He underwent operative fixation and his post operative course was uneventful. He was further treated post operatively with a full knee cast and graded immobilization. At six months he had regained the full range of motion at the knee joint.ConclusionsTo the best of our knowledge, this is the only case report in the literature describing a patella fracture in an individual with nail patella syndrome. We hypothesize that given the extent of pre-existing knee joint impairment in these individuals, functional outcome may be inferior, suggesting the need for more frequent follow-up.

[Current status and expectations in the surgical treatment of recurrent lateral patellar dislocation].

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Zhao, Zhi-Dong; Li, Peng-Cui; Wei, Xiao-Chun

2017-11-25

Up to now, surgical treatment of recurrent lateral patellar dislocation mainly includes: medial patellofemoral ligament reconstruction, tibial tubercle osteotomy, trochleoplasty, lateral retinacular release, derotation osteotomy and so on . Clinical reports show that: the use of a single or combined with several methods have achieved ideal short to mid-term clinical outcomes. However, there is no consolidate criterion concerning the choices of different kinds of surgical ways for the treatment of individual recurrent lateral patellar dislocation. Meanwhile, with the wide use of MPFL reconstruction and other surgical options, there are more and more complications and failures that are worthy and necessary for us to pay attention to, even though its high success rate. The aim of this article is to make a systematic review of the application status of different surgical methods, collecting the positive results we have achieved, illuminating application keys of surgical techniques, guiding patient-specific therapy more precisely. Copyright© 2017 by the China Journal of Orthopaedics and Traumatology Press.

Sinding-Larsen-Johansson syndrome

African Journals Online (AJOL)

dislocation, chondromalacia patellae and prepatellar bursitis.1. Imaging of Sinding-Larsen-Johansson syndrome may require a combination of radiographs, MRI and ultrasound. Lateral radiographs may reveal peripatellar soft-tissue swelling, patella-alta deformity and one or multiple tiny osseous fragments adjacent to.

The Relationship between Chondromalacia Patella, Medial Meniscal Tear and Medial Periarticular Bursitis in Patients with Osteoarthritis.

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Resorlu, Mustafa; Doner, Davut; Karatag, Ozan; Toprak, Canan Akgun

2017-12-01

This study investigated the presence of bursitis in the medial compartment of the knee (pes anserine, semimembranosus-tibial collateral ligament, and medial collateral ligament bursa) in osteoarthritis, chondromalacia patella and medial meniscal tears. Radiological findings of 100 patients undergoing magnetic resonance imaging with a preliminary diagnosis of knee pain were retrospectively evaluated by two radiologists. The first radiologist assessed all patients in terms of osteoarthritis, chondromalacia patella and medial meniscal tear. The second radiologist was blinded to these results and assessed the presence of bursitis in all patients. Mild osteoarthritis (grade I and II) was determined in 55 patients and severe osteoarthritis (grade III and IV) in 45 cases. At retropatellar cartilage evaluation, 25 patients were assessed as normal, while 29 patients were diagnosed with mild chondromalacia patella (grade I and II) and 46 with severe chondromalacia patella (grade III and IV). Medial meniscus tear was determined in 51 patients. Severe osteoarthritis and chondromalacia patella were positively correlated with meniscal tear (p chondromalacia patella (p = 0.023 and p = 0.479, respectively). Evaluation of lateral compartment bursae revealed lateral collateral ligament bursitis in 2 patients and iliotibial bursitis in 5 patients. We observed a greater prevalence of bursitis in the medial compartment of the knee in patients with severe osteoarthritis and medial meniscus tear.

The relation between chondromalacia patella and meniscal tear and the sulcus angle/ trochlear depth ratio as a powerful predictor.

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Resorlu, Hatice; Zateri, Coskun; Nusran, Gurdal; Goksel, Ferdi; Aylanc, Nilufer

2017-01-01

To investigate the relation between chondromalacia patella and the sulcus angle/trochlear depth ratio as a marker of trochlear morphology. In addition, we also planned to show the relationship between meniscus damage, subcutaneous adipose tissue thickness as a marker of obesity, patellar tilt angle and chondromalacia patella. Patients with trauma, rheumatologic disease, a history of knee surgery and patellar variations such as patella alba and patella baja were excluded. Magnetic resonance images of the knees of 200 patients were evaluated. Trochlear morphology from standardized levels, patellar tilt angle, lateral/medial facet ratio, subcutaneous adipose tissue thickness from 3 locations and meniscus injury were assessed by two specialist radiologists. Retropatellar cartilage was normal in 108 patients (54%) at radiological evaluation, while chondromalacia patella was determined in 92 (46%) cases. Trochlear sulcus angle and prepatellar subcutaneous adipose tissue thickness were significantly high in patients with chondromalacia patella, while trochlear depth and lateral patellar tilt angle were low. The trochlear sulcus angle/trochlear depth ratio was also high in chondromalacia patella and was identified as an independent risk factor at regression analysis. Additionally, medial meniscal tear was observed in 35 patients (38%) in the chondromalacia patella group and in 27 patients (25%) in the normal group, the difference being statistically significant (P = 0.033). An increased trochlear sulcus angle/trochlear depth ratio is a significant predictor of chondromalacia patella. Medial meniscus injury is more prevalent in patients with chondromalacia patella in association with impairment in knee biomechanics and the degenerative process.

Chrondoblastoma of the patella

International Nuclear Information System (INIS)

Moser, R.P. Jr.; Uniformed Services Univ. of the Health Sciences, Bethesda, MD; Brockmole, D.M.; Vinh, T.N.; Kransdorf, M.J.; Uniformed Services Univ. of the Health Sciences, Bethesda, MD; Aoki, J.

1988-01-01

This study reviews 16 cases of chondroblastoma of the patella which constitute mearly 6% of a large group of chondroblastomas scattered throughout the skeleton. Both radiologic and histologic appearances of chondroblastomas of the patella are indistinguishable from those of chondroblastomas arising in other sites. A reasonable differential diagnosis, including chondromalacia patella, is discussed together with important therapeutic considerations. (orig.)

Chrondoblastoma of the patella

Energy Technology Data Exchange (ETDEWEB)

Moser, R.P. Jr.; Brockmole, D.M.; Vinh, T.N.; Kransdorf, M.J.; Aoki, J.

1988-09-01

This study reviews 16 cases of chondroblastoma of the patella which constitute mearly 6% of a large group of chondroblastomas scattered throughout the skeleton. Both radiologic and histologic appearances of chondroblastomas of the patella are indistinguishable from those of chondroblastomas arising in other sites. A reasonable differential diagnosis, including chondromalacia patella, is discussed together with important therapeutic considerations.

Patella height changes post high tibial osteotomy

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Siew Ghim Gooi

2017-01-01

Full Text Available Background: Medial opening wedge high tibial osteotomy (HTO is a well-described treatment in early medial compartmental osteoarthritis of the knee. However, two undesirable sequelae may follow –patella baja and changes in the posterior tibial slope (TS. Materials and Methods: We conducted a retrospective study in patients who underwent HTO in our center between September 2009 and February 2017. Preoperative and 6-week postoperative long-leg weight bearing films and lateral knee radiographs were assessed. Pre- and postoperative radiological measurements include the Caton-Deschamps Index (CDI, the mechanical axis deviation (MAD, and the posterior TS. Independant t-test and Pearson correlation test were performed. Results: A total of 106 knees were recruited. The mean age was 48.8 ± 10.8 years. 66 (62.3% and 40 (37.7% knees were from males and females, respectively. The mean pre- and postoperative measurements was (−9.70° ± 3.67° to 0.08° ± 2.80° (−varus; +valgus for the MAD, (7.14° ± 1.78° to 8.72° ± 3.11° for posterior TS, and (0.93° ± 0.084° to 0.82° ± 0.13° for CDI (P ≤ 0.001 for all. The association between patella height change and the level of osteotomy (supra-tubercle vs. infra-tubercle was statistically significant (P < 0.001. A supra-tubercle osteotomy cut significantly lowering patella height (P = 0.011. There was otherwise no statistically significant correlations between patella height changes and the correction angle (P = 0.187 or posterior TS change (P = 0.744. Conclusions: A medial opening wedge HTO above the tibial tubercle was significantly associated with lowering patella height or reducing CDI postoperatively. Based on our results, we would recommend the use of an infra-tubercle osteotomy during the corrective surgery to prevent the complication of patella baja.

Conservative treatment of an anterior-lateral ankle dislocation without an associated fracture in a diabetic patient: a case report

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Panagiotis K. Karampinas

2012-06-01

Full Text Available Anterior or anterior-lateral dislocation of the ankle is a rare condition that can be treated conservatively as well as any other similar types of ankle dislocations without associated fractures. We present a case report of an anterior-lateral ankle dislocation with a concomitant avulsion injury of the ankle's anterior capsule in a diabetic patient that was treated conservatively. At the patient's visit 12 months after the initial injury, he was asymptomatic with full range of motion of the ankle joint. To our knowledge, we could not identify this type of an injury in a diabetic patient that was treated successfully with conservative treatment in the existing literature.

The Relationship between Chondromalacia Patella, Medial Meniscal Tear and Medial Periarticular Bursitis in Patients with Osteoarthritis

Science.gov (United States)

Doner, Davut; Karatag, Ozan; Toprak, Canan Akgun

2017-01-01

Abstract Background This study investigated the presence of bursitis in the medial compartment of the knee (pes anserine, semimembranosus-tibial collateral ligament, and medial collateral ligament bursa) in osteoarthritis, chondromalacia patella and medial meniscal tears. Patients and methods Radiological findings of 100 patients undergoing magnetic resonance imaging with a preliminary diagnosis of knee pain were retrospectively evaluated by two radiologists. The first radiologist assessed all patients in terms of osteoarthritis, chondromalacia patella and medial meniscal tear. The second radiologist was blinded to these results and assessed the presence of bursitis in all patients. Results Mild osteoarthritis (grade I and II) was determined in 55 patients and severe osteoarthritis (grade III and IV) in 45 cases. At retropatellar cartilage evaluation, 25 patients were assessed as normal, while 29 patients were diagnosed with mild chondromalacia patella (grade I and II) and 46 with severe chondromalacia patella (grade III and IV). Medial meniscus tear was determined in 51 patients. Severe osteoarthritis and chondromalacia patella were positively correlated with meniscal tear (p chondromalacia patella (p = 0.023 and p = 0.479, respectively). Evaluation of lateral compartment bursae revealed lateral collateral ligament bursitis in 2 patients and iliotibial bursitis in 5 patients. Conclusions We observed a greater prevalence of bursitis in the medial compartment of the knee in patients with severe osteoarthritis and medial meniscus tear. PMID:29333118

MRI findings in bipartite patella

International Nuclear Information System (INIS)

Kavanagh, Eoin C.; Zoga, Adam; Omar, Imran; Ford, Stephanie; Eustace, Stephen; Schweitzer, Mark

2007-01-01

Bipartite patella is a known cause of anterior knee pain. Our purpose was to detail the magnetic resonance imaging (MRI) features of bipartite patella in a retrospective cohort of patients imaged at our institution. MRI exams from 53 patients with findings of bipartite patella were evaluated to assess for the presence of bone marrow edema within the bipartite fragment and for the presence of abnormal signal across the synchondrosis or pseudarthrosis. Any other significant knee pathology seen at MRI was also recorded. We also reviewed 400 consecutive knee MRI studies to determine the MRI prevalence of bipartite patella. Of the 53 patients with bipartite patella 40 (75%) were male; 35 (66%) had edema within the bipartite fragment. Of the 18 with no edema an alternative explanation for knee pain was found in 13 (72%). Edema within the bipartite fragment was the sole finding in 26 of 53 (49%) patients. Bipartite patella was seen in 3 (0.7%) of 400 patients. In patients with bipartite patella at knee MRI, bone marrow edema within the bipartite fragment was the sole finding on knee MRI in almost half of the patients in our series. (orig.)

Comparison of titanium cable tension band and nickel-titanium patella concentrator for patella fractures.

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Zhao, Quan-Ming; Gu, Xiao-Feng; Cheng, Li; Feng, De-Hong

2017-07-01

Patellar fractures account for approximately 1% of all fractures. Due to the patella's importance as regards the extensor mechanism, effort should be made to preserve the patella. Several operative treatment methods have been introduced for patella fractures. This study aims to compare the clinical effect of a titanium cable tension band and nickeltitanium (NiTi) patella concentrator (NT-PC) in treating patella fractures. Thirty-nine patients with patella fractures were enrolled in this retrospective study. All the patients were treated via the open reduction internal fixation procedure using a titanium cable tension band or NT-PC. All the patients were followed up over an average period of 13 months. The main outcome measures were operation time, time of fracture union, postoperative complications, and Böstman knee scores. Statistical analyses were conducted between the 2 groups. All the patients were operated on successfully. The operation time of the NT-PC treatment group was less than that of the titanium cable tension band treatment group (p cable tension band and NT-PC groups, respectively. No significant difference was observed between the excellent and good results (p > 0.05). Both titanium cable tension band and NT-PC showed good efficacy for the treatment of patellar fractures. NT-PC fixation, a new option for the treatment of patella fractures, is a simple and effective fixation method.

Current concepts of etiology and treatment of chondromalacia patellae.

Science.gov (United States)

Bentley, G; Dowd, G

1984-10-01

Chondromalacia patellae is a distinct clinical entity characterized by retropatellar pain that is associated with recognizable changes in the articular cartilage of the posterior surface of the patella. Several factors may be involved in the etiology, such as severe patella alta, trauma, and, in rare cases, abnormal patellar tracking. Clinical symptoms and signs are reliable in only 50% of cases, but measurable quadriceps wasting, palpable patellofemoral crepitus, and effusion are strongly suggestive. Diagnosis must be confirmed by arthroscopy or direct examination of the posterior surface of the patella. Radiologic measurements of patellofemoral relations are of limited value in diagnosis. The initial pathologic finding is usually surface cartilage breakdown. Radioisotope studies show cartilage cell replication which suggests a healing capacity in early cases following treatment that alters the load through the affected cartilage. There is no evidence of progression to patellofemoral osteoarthritis, which is probably a different entity. The treatment should be conservative where possible with isometric quadriceps exercises and simple anti-inflammatory drugs such as aspirin. Operative treatment is indicated for patients with persistent pain and macroscopic involvement of more than half a centimeter of the articular cartilage surface. The simplest effective procedure that avoids quadriceps dysfunction and fibrosis is a distal patellar tendon medial realignment with lateral release and medial reefing of the quadriceps expansion. Patellectomy is indicated in more extensive involvement of the patella of 2 or more centimeters in diameter, but this must be performed only when the patient has excellent quadriceps function before surgery and is motivated to exercise after surgery.

Luxação lateral bilateral isolada do cotovelo Elbow bilateral lateral dislocation

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Leandro José Reckers

2006-01-01

Full Text Available Os autores apresentam um caso de luxação lateral bilateral isolada de cotovelo em uma paciente do sexo feminino de 48 anos. Optou-se pelo tratamento conservador através de redução fechada sob anestesia geral. Ambos os cotovelos foram imobilizados com gesso axilo-palmar e mantidos a 90º de flexão por três semanas, quando se iniciou a reabilitação. No seguimento de dezoito meses observou-se boa estabilidade e recuperação do arco de movimento de ambos os cotovelos.The authors present an isolated case of bilateral lateral dislocation of the elbow joint in a 48-year old female patient. The conservative treatment was chosen, through closed reduction under general anesthesia. Both elbows were placed in an axillopalmar splint cast and held at a 90 degree angle of flexion for three weeks when rehabilitation began. In the eighteen-month follow-up period, good stability as well as the recovery of the range of motion was observed in both elbows

Chondromalcia patellae

International Nuclear Information System (INIS)

McCauley, T.R.; Kier, R.; Lynch, K.J.

1989-01-01

This paper reports the ability of MR imaging of the knee to detect chondromalacia patellae assessed with T2-weighted and intermediately weighted spin- echo (SE) images. Axial 5 mm SE 2,000/20-80 images of 28 patients who subsequently underwent arthroscopy were reviewed by two radiologists. The radiologists had no knowledge of the arthroscopic results. Signal characteristics and contour of the patellar cartilage were evaluated. Results were correlated with arthroscopic evidence of chondromalacia patellae

Computational Modelling of Patella Femoral Kinematics During Gait Cycle and Experimental Validation

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Maiti, Raman

2016-06-01

The effect of loading and boundary conditions on patellar mechanics is significant due to the complications arising in patella femoral joints during total knee replacements. To understand the patellar mechanics with respect to loading and motion, a computational model representing the patella femoral joint was developed and validated against experimental results. The computational model was created in IDEAS NX and simulated in MSC ADAMS/VIEW software. The results obtained in the form of internal external rotations and anterior posterior displacements for a new and experimentally simulated specimen for patella femoral joint under standard gait condition were compared with experimental measurements performed on the Leeds ProSim knee simulator. A good overall agreement between the computational prediction and the experimental data was obtained for patella femoral kinematics. Good agreement between the model and the past studies was observed when the ligament load was removed and the medial lateral displacement was constrained. The model is sensitive to ±5 % change in kinematics, frictional, force and stiffness coefficients and insensitive to time step.

The problem of chondromalacia patellae.

Science.gov (United States)

Outerbridge, R E; Dunlop, J A

1975-01-01

Daily activity subjects the human patella to forces often several times the individual's body weight. Healthy cartilage can adjust to these forces if they are not too excessive, concentrated, or repetitive. Such abnormal stresses most frequently occur with the disturbance of normal patellar mechanical function. Chondromalacia patellae is the result common to a wide variety of unusual traumata. Treatment must be directed primarily not toward the damaged patellar cartilage but toward a correction of the mechanical abnormality causing it. Until proven otherwise, a young female complaining of knee joint pain, particularly if bilateral, should be considered as suffering from a subluxating patella, with or without chondromalacia patellae.

Joint hypermobility in patients with chondromalacia patellae.

Science.gov (United States)

al-Rawi, Z; Nessan, A H

1997-12-01

The relationship between joint mobility and chondromalacia patellae was reported in a prospective study. A total of 115 patients with chondromalacia patellae were compared with 110 healthy individuals without chondromalacia patellae, matched for age and sex, who served as a control group. The degree of joint mobility was scored on a scale of 0-9. The number of individuals with hypermobile joints and the total mobility scores were significantly higher in patients with chondromalacia patellae when compared to the control group (P chondromalacia patellae when compared with the knees of the control group (P Chondromalacia patellae were bilateral in 57% of our patients. It occurred more frequently in the longer leg and was associated with quadriceps muscle wasting in 50% of patients. Flat feet and backache were reported significantly more often in patients compared with the control group (P chondromalacia patellae.

Fixed-angle plates in patella fractures - a pilot cadaver study

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Wild M

2011-01-01

Full Text Available Abstract Objective Modified anterior tension wiring with K-wires and cannulated lag screws with anterior tension wiring are currently the fixation of choice for patellar fractures. Failure of fixation, migration of the wires, postoperative pain and resulting revision surgery, however, are not uncommon. After preliminary biomechanical testing of a new fixed-angle plate system especially designed for fixation of patella fractures the aim of this study was to evaluate the surgical and anatomical feasibility of implanting such a plate-device at the human patella. Methods In six fresh unfixed female cadavers without history of previous fractures around the knee (average age 88.8 years a bilateral fixed-angle plate fixation of the patella was carried out after previous placement of a transverse central osteotomy. Operative time, intra-operative problems, degree of retropatellar arthritis (following Outerbridge, quality of reduction and existence of any intraarticular screw placement have been raised. In addition, lateral and anteroposterior radiographs of all specimens were made. Results Due to the high average age of 88.8 years no patella showed an unimpaired retropatellar articular surface and all were severely osteoporotic, which made a secure fixation of the reduction forceps during surgery difficult. The operation time averaged 49 minutes (range: 36-65. Although in postoperative X-rays the fracture gap between the fragments was still visible, the analysis of the retropatellar surface showed no residual articular step or dehiscence > 0.5 mm. Also in a total of 24 inserted screws not one intraarticular malposition was found. No intraoperative complications were noticed. Conclusions Osteosynthesis of a medial third patella fracture with a bilateral fixed-angle plate-device is surgically and anatomically feasible without difficulties. Further studies have to depict whether the bilateral fixed-angle plate-osteosynthesis of the patella displays

Tuberculosis of the patella

International Nuclear Information System (INIS)

Dhillon, M.S.; Rao, S.S.; Nagi, O.N.; Sandhu, M.S.; Vasisht, R.K.

1998-01-01

A rare case of tuberculosis of the patella is presented. Diagnostic features include an osteolytic lesion in the patella with flaky sequestrum, associated with typical clinical features. Treatment should be urgent and should include a regimen of surgical debridement along with four antitubercular drugs. Once the joint is involved, the end results become less satisfactory. (orig.)

The association of patellofemoral joint morphology with chondromalacia patella: a quantitative MRI analysis.

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Tuna, Burcu Kaya; Semiz-Oysu, Aslıhan; Pekar, Bilhan; Bukte, Yasar; Hayirlioglu, Alper

2014-01-01

The relationship of patellofemoral congruency with chondromalacia patellae (CP) was retrospectively evaluated. Lateral patellar tilt angle (LPTA), sulcus angle (SA), trochlear depth (TD), and patella angle (PA) were measured at 301 knee magnetic resonance images and compared between groups with and without CP. In the CP group, LPTA and TD were significantly low (P.05). The parameters were also compared between groups with mild and severe CP, and no significant difference was found (P>.05). Our results demonstrate that patellar tilt and trochlear dysplasia are related to the presence but not the degree of CP. Copyright © 2014 Elsevier Inc. All rights reserved.

Temporomandibular joint dislocation in an epileptic and mentally ...

African Journals Online (AJOL)

Theories regarding the pathogenesis of TMJ dislocation propose laxity of TMJ ligaments or capsule, excessive activity of the lateral pterygoid muscle (LPM)and erosion of the eminence'. TMJ dislocation can occur in an anterior, posterior, lateral and superior direction'. Clinical presentation of dislocated TMJ includes inability ...

A double patella-like condition secondary to synovial osteochondromatosis

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Kajikawa Yoshiteru

2012-09-01

Full Text Available Abstract To our knowledge, this is the first case of synovial osteochondromatosis in a patient presenting with a double patella-like condition. The true duplication of the patella, which is called double patella, is extremely rare. In our case, the operative and histopathological findings showed that the double patella-like condition was secondarily induced by synovial osteochondromatosis. Synovial osteochondromatosis should be considered as a differential diagnosis for congenital double patella.

Injury patterns of medial patellofemoral ligament after acute lateral patellar dislocation in children: Correlation analysis with anatomical variants and articular cartilage lesion of the patella

International Nuclear Information System (INIS)

Zhang, Guang-ying; Ding, Hong-yu; Zheng, Lei; Ji, Bing-jun; Shi, Hao; Feng, Yan

2017-01-01

To assess the relationship between injury patterns of medial patellofemoral ligament (MPFL) and anatomical variants and patellar cartilage lesions after acute lateral patellar dislocation (LPD) in children. MR images were obtained in 140 children with acute LPD. Images were acquired and evaluated using standardised protocols. Fifty-eight cases of partial MPFL tear and 75 cases of complete MPFL tear were identified. Injuries occurred at an isolated patellar insertion (PAT) in 52 cases, an isolated femoral attachment (FEM) in 42 cases and an isolated mid-substance (MID) in five cases. More than one site of injury was identified in 34 cases. Compared with Wiberg patellar type C, Wiberg patellar type B predisposed to complete MPFL tear (P = 0.042). No correlations were identified between injury patterns of MPFL and trochlear dysplasia, patellar height and tibial tuberosity-trochlear groove distance (P > 0.05). Compared with partial MPFL tear, complete MPFL tear predisposed to Grade-IV and Grade-V patellar chondral lesion (P = 0.02). There were no correlations between incidence of patellar cartilage lesion and injury locational-subgroups of MPFL (P = 0.543). MPFL is most easily injured at the PAT in children. Wiberg patellar type B predisposes to complete MPFL tear. Complete MPFL tear predisposes to a higher grade of patellar chondral lesion. (orig.)

Injury patterns of medial patellofemoral ligament after acute lateral patellar dislocation in children: Correlation analysis with anatomical variants and articular cartilage lesion of the patella

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Zhang, Guang-ying; Ding, Hong-yu [Shandong Provincial Qianfoshan Hospital of Shandong University, Department of Ultrasonography, Jinan (China); Zheng, Lei; Ji, Bing-jun [Shandong Provincial Corps Hospital of Chinese People' s Armed Police Force, Department of Radiology, Jinan (China); Shi, Hao [Shandong Provincial Qianfoshan Hospital of Shandong University, Department of Radiology, Jinan (China); Feng, Yan [Affiliated Hospital of Binzhou Medical College, Department of Radiology, Binzhou (China)

2017-03-15

To assess the relationship between injury patterns of medial patellofemoral ligament (MPFL) and anatomical variants and patellar cartilage lesions after acute lateral patellar dislocation (LPD) in children. MR images were obtained in 140 children with acute LPD. Images were acquired and evaluated using standardised protocols. Fifty-eight cases of partial MPFL tear and 75 cases of complete MPFL tear were identified. Injuries occurred at an isolated patellar insertion (PAT) in 52 cases, an isolated femoral attachment (FEM) in 42 cases and an isolated mid-substance (MID) in five cases. More than one site of injury was identified in 34 cases. Compared with Wiberg patellar type C, Wiberg patellar type B predisposed to complete MPFL tear (P = 0.042). No correlations were identified between injury patterns of MPFL and trochlear dysplasia, patellar height and tibial tuberosity-trochlear groove distance (P > 0.05). Compared with partial MPFL tear, complete MPFL tear predisposed to Grade-IV and Grade-V patellar chondral lesion (P = 0.02). There were no correlations between incidence of patellar cartilage lesion and injury locational-subgroups of MPFL (P = 0.543). MPFL is most easily injured at the PAT in children. Wiberg patellar type B predisposes to complete MPFL tear. Complete MPFL tear predisposes to a higher grade of patellar chondral lesion. (orig.)

Treatment of peroneal tendon dislocation and coexisting medial and lateral ligamentous laxity in the ankle joint.

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Ziai, Pejman; Sabeti-Aschraf, Manuel; Fehske, Kai; Dlaska, Constantin E; Funovics, Philipp; Wenzel, Florian; Graf, Alexandra; Buchhorn, Tomas

2011-06-01

Acute dislocation of the peroneal tendon is caused by massive combined flexion-torsion trauma supported by preexisting ligamentous laxity of the ankle joint. This study aimed to investigate the clinical outcome of combined treatment of peroneal tendon dislocation and lateral and medial ligamentous laxity. Between 2005 and 2007, forty-two patients with peroneal tendon dislocation and coexisting ligamentous laxity were treated. The superior extensor retinaculum was reconstructed using anchor technique and periosteal flap repair, whereas the preexisting ligamentous laxity with regard to the extensor inferior retinaculum was addressed using anchor reconstruction. All patients underwent arthroscopy prior to surgery. Thirty-eight of a total of 42 patients (aged 17-31) completed the 24-month follow-up. Clinical and arthroscopic examination was accomplished consistently by always the same two surgeons. Postoperative follow-up comprised clinical evaluation after 3, 6, 12 and 24 months. Clinical results showed a significant (Pankle joint following arthroscopy results in good clinical outcome and high patient satisfaction. Case series, Level IV.

Imaging of patellofemoral disorders

International Nuclear Information System (INIS)

Elias, D.A.; White, L.M.

2004-01-01

Anterior knee pain is a common symptom, which may have a large variety of causes including patellofemoral pathologies. Patellofemoral maltracking refers to dynamic abnormality of patellofemoral alignment and has been measured using plain film, computed tomography (CT) and magnetic resonance imaging (MRI) using static and kinematic techniques. Patellar dislocation is usually transient, but specific conventional radiographic and MRI features may provide evidence of prior acute or chronic dislocation. In addition, chondromalacia patellae, osteochondritis dissecans, patellofemoral osteoarthritis, excessive lateral pressure syndrome, and bipartite patella have all been implicated in causing patellofemoral pain. The imaging and clinical features of these processes are reviewed, highlighting the specific diagnostic features of each condition

Imaging of patellofemoral disorders

Energy Technology Data Exchange (ETDEWEB)

Elias, D.A. E-mail: david.elias@kingsch.nhs.uk; White, L.M

2004-07-01

Anterior knee pain is a common symptom, which may have a large variety of causes including patellofemoral pathologies. Patellofemoral maltracking refers to dynamic abnormality of patellofemoral alignment and has been measured using plain film, computed tomography (CT) and magnetic resonance imaging (MRI) using static and kinematic techniques. Patellar dislocation is usually transient, but specific conventional radiographic and MRI features may provide evidence of prior acute or chronic dislocation. In addition, chondromalacia patellae, osteochondritis dissecans, patellofemoral osteoarthritis, excessive lateral pressure syndrome, and bipartite patella have all been implicated in causing patellofemoral pain. The imaging and clinical features of these processes are reviewed, highlighting the specific diagnostic features of each condition.

Bone-scintigraphy in painful bipartite patella

International Nuclear Information System (INIS)

Iossifidis, A.; Brueton, R.N.; Nunan, T.O.

1995-01-01

Although, the use of technetium scintigraphy in the assessment of anterior knee pain has been described, no reference has been made to the scintigraphic appearances of painful bipartite patella. We report the scintigraphic-appearances of painful bipartite patella in 25-year-old man a 2 1/2 years history of unexplained patellar pain. Painful bipartite patella is a rare cause of chronic post-traumatic patellar pain. Bone scintigraphy, by demonstrating increased uptake by the painful accessory bipartite fragment, appears to be an imaging method of choice in the diagnosis of this condition. (orig./MG)

Position of the Patella among Emirati Adult Knees. Is Insall-Salvati Ratio Applicable to Middle-Easterners?

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Saeed Althani

2016-04-01

Full Text Available Background: Abnormal patellar height is associated with anterior knee pain and several conditions that affect the patellofemoral joint. The aim of this study was to 1 report the incidence of patella alta and patella baja and 2 investigate whether the normal limits of the Insall-Salvati ratio is applicable in adult Middle-Easterners. Methods: A radiographic review of the lateral radiographs of 736 Middle-Eastern knees were performed. Patellar tendon length (TL and the patellar length (TP was digitally measured and the ratios of these measures was used to calculate the Insall-Salvati ratio. Results: The overall mean TL/PL ratio was 1.20±0.17. The Insall-Salvati ratio was higher (p=0.0013 in males (1.22± 0.12 than in females (1.18±0.17. According to our measurement, the recommended levels for defining abnormal patellar position should be 0.86 for patella baja and 1.54 for patella alta. Conclusion: The use of TL/PL ratio demonstrated a higher incidence of patella alta and a higher mean TL/PL ratio compared to other techniques. The normal ranges for the TL/PL differs from western populations and may be attributed to lifestyle differences.

ARTHROSCOPIC TREATEMENT OF PATELLA FRACTURES IN CHILDREN

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Igor V. Timofeev

2017-03-01

Full Text Available Introduction. The frequency of patellar fractures is approximately 0.5% to 1.5% of all skeletal injuries. The following types of fractures can be distinguished: avulsive, transverse, longitudinal, and comminuted. In cases of displacement of more than 2–3 mm and quadriceps tendon injuries open reduction and internal fixation with the restoration of the articular surface is more preferable. In cases of longitudinal fractures, arthroscopy is regarded as a highly effective method of surgical treatment. Materials and methods. Using arthroscopy, we have operated on 4 patients with longitudinal fracture of the patella. The average age of the injured persons was 15.4 years (14–17. These were 3 males and 1 female. All patients had sport-related injuries. Because of the longitudinal fracture of the patella, the lateral knee extensor mechanism remained intact, and arthrosopy-assisted surgical intervention with closed reposition of fragments and transcutaneous wire fixation was performed without wire suturing. Results and discussion. Minimal invasiveness, the possibility of visual control over the recovery quality of patellar surface, the reliability of fragment fixation, and a significant reduction in the subsequent rehabilitation make arthroscopy a highly effective method of surgical treatment for patellar fractures.

Breeding implications resulting from classification of patellae luxation in dogs.

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van Grevenhof, E M; Hazewinkel, H A W; Heuven, H C M

2016-08-01

Patellar luxation (PL) is one of the major hereditary orthopaedic abnormalities observed in a variety of dog breeds. When the patellae move sideways out of the trochlear groove, this is called PL. The PL score varies between dogs from normal to very severe. Reducing the prevalence of PL by breeding could prevent surgery, thereby improve welfare. Orthopaedic specialists differentiate between normal and loose patellae, where the patellae can be moved to the edge of the trochlear groove, considering scoring loose patellae as normal in the future. Loose patellae are considered acceptable for breeding so far by the breeding organization. The aim of this study was to analyse the genetic background of PL to decide on the importance of loose patellae when breeding for healthy dogs. Data are available from two dog breeds, that is Flat-coated Retrievers (n = 3808) and Kooiker dogs (n = 794), with a total of 4602 dogs. Results show that loose patellae indicate that dogs are genetically more susceptible to develop PL because family members of the dogs with loose patellae showed more severe PL. In addition, the estimated breeding values for dogs with loose patellae indicate that breeding values of dogs with loose patellae were worse than breeding values obtained for dogs with a normal score. Given these results, it is advised to orthopaedic specialists to continue to score loose patellae as a separate class and to dog breeders to minimize the use of dogs in breeding with a genetically higher susceptibility for PL. © 2015 Blackwell Verlag GmbH.

Influence of the pneumatic tourniquet on patella tracking in total knee arthroplasty: a prospective randomized study in 100 patients

DEFF Research Database (Denmark)

Husted, Henrik; Toftgaard Jensen, T

2005-01-01

One hundred consecutive patients with osteoarthritis of the knee joint and scheduled for primary total knee arthroplasty performed in a bloodless field were prospectively randomized to have the tourniquet inflated on either straight leg or maximally flexed knee. There was no difference in the num...... deflation led to better patella tracking and saved 5 (31%) of 16 releases with no difference between groups. We recommend tourniquet deflation and reevaluation of patella tracking before performing lateral release in patellar maltracking....

Current concepts review: Fractures of the patella

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Gwinner, Clemens; Märdian, Sven; Schwabe, Philipp; Schaser, Klaus-D.; Krapohl, Björn Dirk; Jung, Tobias M.

2016-01-01

Fractures of the patella account for about 1% of all skeletal injuries and can lead to profound impairment due to its crucial function in the extensor mechanism of the knee. Diagnosis is based on the injury mechanism, physical examination and radiological findings. While the clinical diagnosis is often distinct, there are numerous treatment options available. The type of treatment as well as the optimum timing of surgical intervention depends on the underlying fracture type, the associated soft tissue damage, patient factors (i.e. age, bone quality, activity level and compliance) and the stability of the extensor mechanism. Regardless of the treatment method an early rehabilitation is recommended in order to avoid contractures of the knee joint capsule and cartilage degeneration. For non-displaced and dislocated non-comminuted transverse patellar fractures (2-part) modified anterior tension band wiring is the treatment of choice and can be combined – due to its biomechanical superiority – with cannulated screw fixation. In severe comminuted fractures, open reduction and fixation with small fragment screws or new angular stable plates for anatomic restoration of the retropatellar surface and extension mechanism results in best outcome. Additional circular cerclage wiring using either typical metal cerclage wires or resorbable PDS/non-resorbable FiberWires increases fixation stability and decreases risk for re-dislocation. Distal avulsion fractures should be fixed with small fragment screws and should be protected by a transtibial McLaughlin cerclage. Partial or complete patellectomy should be regarded only as a very rare salvage operation due to its severe functional impairment. PMID:26816667

Rare cause of knee pain after martial arts demonstration: a case report.

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Armstrong, Marc B; Thurber, Jalil

2013-04-01

Patellar dislocations are a commonly treated injury in the Emergency Department (ED), with a majority of cases involving lateral subluxation of the patella outside of the joint space. Intra-condylar dislocations of the patella are rare. Of the two types of axis rotation, vertical and horizontal, the vertical occurs five times less frequently. These injuries most often undergo open reduction or, at best, closed reduction under general anesthesia. To remind Emergency Physicians to consider this injury in any patient with severe knee pain and limited mobility, even with a history that is lacking significant trauma. We present a case of intra-condylar patellar dislocation with vertical axis rotation. This injury is no longer primarily attributed to the young and, barring fracture, closed reduction in the ED should be considered. Copyright © 2013 Elsevier Inc. All rights reserved.

Alignment in the transverse plane, but not sagittal or coronal plane, affects the risk of recurrent patella dislocation.

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Takagi, Shigeru; Sato, Takashi; Watanabe, Satoshi; Tanifuji, Osamu; Mochizuki, Tomoharu; Omori, Go; Endo, Naoto

2017-11-17

Abnormalities of lower extremity alignment (LEA) in recurrent patella dislocation (RPD) have been studied mostly by two-dimensional (2D) procedures leaving three-dimensional (3D) factors unknown. This study aimed to three-dimensionally examine risk factors for RPD in lower extremity alignment under the weight-bearing conditions. The alignment of 21 limbs in 15 RPD subjects was compared to the alignment of 24 limbs of 12 healthy young control subjects by an our previously reported 2D-3D image-matching technique. The sagittal, coronal, and transverse alignment in full extension as well as the torsional position of the femur (anteversion) and tibia (tibial torsion) under weight-bearing standing conditions were assessed by our previously reported 3D technique. The correlations between lower extremity alignment and RPD were assessed using multiple logistic regression analysis. The difference of lower extremity alignment in RPD between under the weight-bearing conditions and under the non-weight-bearing conditions was assessed. In the sagittal and coronal planes, there was no relationship (statistically or by clinically important difference) between lower extremity alignment angle and RPD. However, in the transverse plane, increased external tibial rotation [odds ratio (OR) 1.819; 95% confidence interval (CI) 1.282-2.581], increased femoral anteversion (OR 1.183; 95% CI 1.029-1.360), and increased external tibial torsion (OR 0.880; 95% CI 0.782-0.991) were all correlated with RPD. The tibia was more rotated relative to femur at the knee joint in the RPD group under the weight-bearing conditions compared to under the non-weight-bearing conditions (p alignment parameters in the transverse plane related to the risk of RPD, while in the sagittal and coronal plane alignment parameters did not correlate with RPD. The clinical importance of this study is that the 3D measurements more directly, precisely, and sensitively detect rotational parameters associated with RPD and

Asymmetric, compressive, SiGe epilayers on Si grown by lateral liquid-phase epitaxy utilizing a distinction between dislocation nucleation and glide critical thicknesses

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O'Reilly, Andrew J.; Quitoriano, Nathaniel

2018-01-01

Uniaxially strained Si1-xGex channels have been proposed as a solution for high mobility channels in next-generation MOSFETS to ensure continued device improvement as the benefits from further miniaturisation are diminishing. Previously proposed techniques to deposit uniaxially strained Si1-xGex epilayers on Si (0 0 1) substrates require multiple deposition steps and only yielded thin strips of uniaxially strained films. A lateral liquid-phase epitaxy (LLPE) technique was developed to deposit a blanket epilayer of asymmetrically strained Si97.4Ge2.6 on Si in a single step, where the epilayer was fully strained in the growth direction and 31% strain-relaxed in the orthogonal direction. The LLPE technique promoted the glide of misfit dislocations, which nucleated in a region with an orthogonal misfit dislocation network, into a region where the dislocation nucleation was inhibited. This created an array of parallel misfit dislocations which were the source of the asymmetric strain. By observing the thicknesses at which the dislocation network transitions from orthogonal to parallel and at which point dislocation glide is exhausted, the separate critical thicknesses for dislocation nucleation and dislocation glide can be determined.

Cartilage degeneration in the human patellae and its relationship to the mineralisation of the underlying bone: a key to the understanding of chondromalacia patellae and femoropatellar arthrosis?

Science.gov (United States)

Eckstein, F; Putz, R; Müller-Gerbl, M; Steinlechner, M; Benedetto, K P

1993-01-01

According to the literature subchondral bone plays a significant role in the transmission of load through joints and in the pathogenesis of osteoarthrosis. Therefore the degeneration of the articular cartilage was investigated in the patellae from 30 dissecting-room specimens and of 20 patients, previously submitted to arthroscopy, and subchondral mineralisation of their underlying bone was at the same time assessed by means of CT osteoabsorptiometry. Lateral cartilage lesions were localised over highly mineralised subchondral bone; these appear to be due to long-term stress. They were mainly found in the older specimens and showed a high rate of progression with increasing age. Medially localised cartilage lesions, on the other hand, were situated in a transitional region between moderate and slight subchondral mineralisation; they may be caused by infrequent stress peaks and by shear stress in the articular cartilage, the very medial part of the joint being deprived of mechanical stimulation for much of the time. These lesions were to be found predominantly in the younger specimens and showed little progress with advancing age. Patients with lateral cartilage degeneration exhibited higher, patients with medial chondromalacia patellae lower mineralisation than normals. Their density patterns therefore indicate a different mechanical pathogenesis of the cartilage lesions in the lateral and medial facet. It could be shown that CT osteoabsorptiometry allows an assessment of the mechanical situation, present in individual femoro-patellar joints, and that this situation is highly relevant for the pathogenesis of patellar cartilage degeneration.

Arthroscopy in the diagnosis of chondromalacia patellae.

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Leslie, I J; Bentley, G

1978-01-01

Chondromalacia patellae is difficult to diagnosis clinically with accuracy. In order to clarify the relevant symptoms and signs, 78 patients presenting with a clinical diagnosis of chondromalacia were examined by arthroscopy. In 49% of the knees no abnormalities were found. Presenting symptoms were similar in the normal and abnormal groups. Physical signs were more helpful in diagnosis and it is considered that the presence of an effusion, quadriceps wasting, and patello-femoral crepitus are the most important clinical findings in the diagnosis of chondromalacia patellae. The arthroscope is valuable instrument in establishing the diagnosis of chondromalacia patellae especially in the teenage female. Images PMID:749700

An irreducible ankle fracture dislocation: the Bosworth injury

NARCIS (Netherlands)

Schepers, Tim; Hagenaars, Tjebbe; den Hartog, Dennis

2012-01-01

Irreducible fracture dislocations of the ankle are rare and represent true orthopedic emergencies. We present a case of a fracture dislocation that was irreducible owing to a fixed dislocation of the proximal fibular fragment posterior to the lateral ridge of the tibia. This particular type of

Trochleoplasty as a Solitary Treatment for Recurrent Patellar Dislocation Results in Good Clinical Outcome in Adolescents.

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Camathias, Carlo; Studer, Katrin; Kiapour, Ata; Rutz, Erich; Vavken, Patrick

2016-11-01

The essential static patellar stabilizer is a normal-shaped trochlear groove. A dysplastic groove destabilizes the patella. Trochleoplasty approaches this underlying condition and reshapes the trochlea. However, studies have reported on trochleoplasty for revision cases or as accompanied by other interventions. The effect of trochleoplasty alone remains unexplained. To introduce trochleoplasty as a stand-alone treatment for recurrent patellar dislocation and to compare its pre- to postoperative functional and clinical variables. Case series; Level of evidence, 4. A trochleoplasty was performed in 50 knees (27 right) in 44 patients (30 females; mean ± SD age, 15.6 ± 2.0 years). The indication for surgery was recurrent patellar dislocation not responding to nonoperative treatment (>6 months), with types B through D dysplasia and closed or closing physes in adolescents aged 10 to 20 years. Assessment included J-sign and apprehension test, Kujala and Lysholm scores, patients' subjective assessment and activity level according to the International Knee Documentation Committee questionnaire, and patients' overall satisfaction. The Caton-Deschamps ratio and the lateral condyle index were measured. Pre- versus postoperative values were compared with a paired Wilcoxon signed-rank test. The minimum follow-up was 24 months (33 ± 10.6 months). The Kujala score improved from 71 preoperatively to 92 postoperatively (P debridement. In this study, trochleoplasty as a solitary treatment for recurrent patellofemoral dislocations in patients with trochlear dysplasia resulted in good clinical outcomes if severe torsional and axial malalignment was excluded. Kujala and Lysholm scores increased postoperatively, as well as subjective International Knee Documentation Committee assessment of outcomes, activity level, and overall satisfaction. © 2016 The Author(s).

Chondromalacia patellae: fat-suppressed MR imaging.

Science.gov (United States)

Rose, P M; Demlow, T A; Szumowski, J; Quinn, S F

1994-11-01

To evaluate the accuracy of fat-suppressed magnetic resonance (MR) imaging in diagnosing chondromalacia patellae. Seventy-one patients underwent fat-suppressed MR imaging and arthroscopy of the patellofemoral compartment. Findings were classified as early or advanced chondromalacia or as normal and were correlated with arthroscopic findings. Early and advanced stages of chondromalacia patellae were reliably detected, with positive predictive values of 85% and 92%, respectively. Specificity in early stages was 94% and in late stages was 98%. However, the overall accuracies did not differ substantially from those reported in studies that did not use fat-suppressed imaging. Axial, fat-suppressed MR imaging accurately depicts changes caused by chondromalacia patellae. Early stages can be seen as intrasubstance changes of increased signal intensity. Results of this study suggest a high degree of specificity in excluding both early and advanced changes.

Patellofemoral anatomy and biomechanics: current concepts

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ZAFFAGNINI, STEFANO; DEJOUR, DAVID; GRASSI, ALBERTO; BONANZINGA, TOMMASO; MUCCIOLI, GIULIO MARIA MARCHEGGIANI; COLLE, FRANCESCA; RAGGI, FEDERICO; BENZI, ANDREA; MARCACCI, MAURILIO

2013-01-01

The patellofemoral joint, due to its particular bone anatomy and the numerous capsuloligamentous structures and muscles that act dynamically on the patella, is considered one of the most complex joints in the human body from the biomechanical point of view. The medial patellofemoral ligament (MPFL) has been demonstrated to contribute 60% of the force that opposes lateral displacement of the patella, and MPFL injury results in an approximately 50% reduction in the force needed to dislocate the patella laterally with the knee extended. For this reason, recent years have seen a growing interest in the study of this important anatomical structure, whose aponeurotic nature has thus been demonstrated. The MPFL acts as a restraint during motion, playing an active role under conditions of laterally applied stress, but an only marginal role during natural knee flexion. However, it remains extremely difficult to clearly define the anatomy of the MPFL and its relationships with other anatomical structures. PMID:25606512

Remodeled articular surface after surgical fixation of patella fracture in a child

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Moruf Babatunde Yusuf

2017-01-01

Full Text Available Patella fracture is uncommon in pediatric age group and their patella is better preserved in any class of patella fracture. We reported a case of a 13-year-old male with right patella fracture nonunion. He had open reduction and internal fixation using tension band wire device. Fracture union was monitored with serial radiographs and he was followed up for 60 weeks. There was articular surface step after surgical fixation of the patella fracture. At 34 weeks postoperative, there was complete remodeling of the articular surface with good knee function after removal of the tension band wire. Children have good capacity of bone remodeling after fracture. Little retropatella step in a child after patella fracture surgical fixation will remodel with healing.

Traumatic separation of a type I patella bipartite in a sportsman

DEFF Research Database (Denmark)

Ottesen, Casper Smedegaard; Barfod, Kristoffer Weisskirchner; Holck, Kim

2014-01-01

fibrocartilage was found on both parts of the patella. Asymptomatic patella bi-partite was found on X-ray imaging of the patient's left knee, and he was diagnosed to have traumatic separation of a type I patella bipartite. The diagnosis was confirmed by surgical and radiological findings....

The influence of subchondral vascularisation on chondromalacia patellae.

Science.gov (United States)

Neusel, E; Graf, J

1996-01-01

An experiment was carried out on 40 rabbits in which the blood supply to the patella was interrupted for periods from 2 weeks to 6 months. With prolonged ischaemia, there were clear changes in the articular cartilage which were comparable with those seen in chondromalacia patellae.

Thermography in the detection and follow up of chondromalacia patellae.

Science.gov (United States)

Vujcić, M; Nedeljković, R

1991-01-01

Although diagnostic criteria for chondromalacia patellae exist, the disease is often accompanied by physical signs which are limited or non-diagnostic. Thermographic examination was performed in 157 patients with clinical diagnosis of chondromalacia patellae in 86 patients after surgical treatment for chondromalacia, and in 308 controls. Thermography can help the clinicians in establishing the diagnosis of chondromalacia patellae, but by itself is not sufficiently specific. The specificity of thermography was dependent on age, ranging from 90% for the 15-24 year age group to 65% for the 45-54 year age group. Sensitivity of the method was 68%. Thermography can disclose other knee disorders which imitate chondromalacia patellae. Images PMID:1768161

Fractures of the patella in children and adolescents

DEFF Research Database (Denmark)

Schmal, Hagen; Strohm, Peter C; Niemeyer, Philipp

2010-01-01

Fractures of the patella in children and adolescents are rare injuries with particular characteristics. The aim of this study was an analysis of epidemiology, treatment strategy and outcome of this injury. Between 1992 and 2006 all fractures of the patella in patients with an age 5 16 years were...

Recombination properties of dislocations in GaN

Science.gov (United States)

Yakimov, Eugene B.; Polyakov, Alexander Y.; Lee, In-Hwan; Pearton, Stephen J.

2018-04-01

The recombination activity of threading dislocations in n-GaN with different dislocation densities and different doping levels was studied using electron beam induced current (EBIC). The recombination velocity on a dislocation, also known as the dislocation recombination strength, was calculated. The results suggest that dislocations in n-GaN giving contrast in EBIC are charged and surrounded by a space charge region, as evidenced by the observed dependence of dislocation recombination strength on dopant concentration. For moderate (below ˜108 cm-2) dislocation densities, these defects do not primarily determine the average diffusion length of nonequilibrium charge carriers, although locally, dislocations are efficient recombination sites. In general, it is observed that the effect of the growth method [standard metalorganic chemical vapor deposition (MOCVD), epitaxial lateral overgrowth versions of MOCVD, and hydride vapor phase epitaxy] on the recombination activity of dislocations is not very pronounced, although the average diffusion lengths can widely differ for various samples. The glide of basal plane dislocations at room temperature promoted by low energy electron irradiation does not significantly change the recombination properties of dislocations.

Perilunate Dislocation

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John Jiao

2016-09-01

Full Text Available History of present illness: A 25-year-old female presented to the emergency department with left wrist pain following a fall off a skateboard. The patient fell on her outstretched left wrist with the wrist dorsiflexed and reported immediate sharp pain to her left wrist that was worse with movement. She denied other trauma. Significant findings: In the left lateral wrist x-ray, the lunate (outlined in blue is dislocated from the rest of the wrist bones (yellow line but still articulates with the radius (red line. The capitate (yellow line does not sit within the distal articulation of the lunate and is displaced dorsally. Additionally, a line drawn through the radius and lunate (green line fails to intersect with the capitate. This is consistent with a perilunate dislocation. This is compared to a lunate dislocation, where the lunate itself is displaced and turned ventrally (spilled teacup and the proximal aspect does not articulate with the radius. Discussion: A perilunate dislocation is a significant closed wrist injury that is easily missed on standard anterior-posterior imaging. These dislocations are relatively rare, involving only 7% of all carpal injuries and are associated with high-energy trauma onto a hyperextended wrist, such as falls from a height, motor vehicle accidents, and sports injuries.1 An untreated perilunate dislocation is associated with high risk of chronic carpal instability and post-traumatic arthritis. If the mechanism of injury is sufficient to suspect perilunate dislocation, multiple radiographic views of the wrist should be ordered. Patients should receive prompt orthopedic consultation for open reduction and ligamentous repair. Even after successful identification and subsequent surgical repair, median nerve neuropathy and post-traumatic arthritis are frequent.2-3

Thermography in the detection and follow up of chondromalacia patellae.

OpenAIRE

Vujcić, M; Nedeljković, R

1991-01-01

Although diagnostic criteria for chondromalacia patellae exist, the disease is often accompanied by physical signs which are limited or non-diagnostic. Thermographic examination was performed in 157 patients with clinical diagnosis of chondromalacia patellae in 86 patients after surgical treatment for chondromalacia, and in 308 controls. Thermography can help the clinicians in establishing the diagnosis of chondromalacia patellae, but by itself is not sufficiently specific. The specificity of...

MR imaging of chondramalacia patella

International Nuclear Information System (INIS)

Yulish, B.S.; Montanez, J.; Mulopulos, G.P.; Goodfellow, D.; Dollinger, B.; Bryan, P.J.; Modic, M.T.

1986-01-01

Because of its inherent soft-tissue contrast, MR imaging can distinguish hyaline articular cartilage, fibrocartilage, and cortical and medullary bone, and thus seems a method ideally suited to examine the posterior patellar hyaline articular cartilage. The authors studied the knees of people with suspected chondromalacia patella using MR imagine and compared our findings to normal knees and, where available, results of surgery. They find that we can distinguish swollen cartilage, irregular cartilage, absent cartilage, and bony patellar defects. Joint fluid and meniscal injuries could also be identified. MR imaging is a useful method for evaluation of chondromalacia patella and may reduce the need for arthroscopy and arthrography for diagnosis

Transverse patella fracture in a ten year old boy: case report ...

African Journals Online (AJOL)

Patella fractures are rare in children. Transverse fractures in particular are an uncommon pattern. We report a case of a transverse patella fracture in a ten year old boy. He presented with inability to actively extend his left knee, two months after a fall. On evaluation he was found to have a transverse fracture of his left patella.

The MRI study of correlation between patella location and chondromalacia

International Nuclear Information System (INIS)

Lu Wei; Chen Shuang; Yang Jun

2011-01-01

Objective: To discuss the relationship between patella location and chondromalacia patella, explore its mechanism and clinical significance. Methods: Knee joint MRI was performed in 1052 patients (506 men and 546 female). Among them, there were 299 patients (100 men and 199 female) with chondromalacia patella. They were divide into the group of 1-19, the group of 20-39, the group of 40-59 years old and the group of older than 60 years to compute the positive rate respectively. Insall-Salvati method was used to measure the length of chondromalacia ligaments (L) and the length of chondromalacia path (P). The relationship between patella location and chondromalacia was tested by using t test and χ 2 test. Results: The total positive rate of chondromalacia patella was 28.4% (299/1052). In female it was 36.4% (199/546) and in men was 19.8% (100/506). The group of 1-19 years old had 16 patients (16.8%, 16/95). The group of 20-39 years old had 71 patients (17.9%, 71/396). The group of 40- 59 years old had 116 patients (33.2%, 116/349). The group of older than 60 years had 96 patients (45.3%, 96/212). The positive rate of chondromalacia patella increased with age. The L/P value of normal group and chondromalacia patella group were 1.15±0.15 and 1.24±0.17 respectively. The L/P value of normal group of men and women were 1.13±0.15 and 1.17±0.14 respectively. The L/P value of chondromalacia patella group of men and women were 1.20±0.17 and 1.26±0.16 respectively. The Insall- Salvati index of age groups showed significant differences. The L/P value of pathological changes group and normal group of 1-19 years old were 1.38±0.25 and 1.24±0.16 respectively. The L/P value of pathological changes group and normal group of 20-39 years old were 1.24±0.17 and 1.15±0.16 respectively. The L/P value of pathological changes group and normal group of 40-59 years old were 1.24±0.16 and 1.12±0.12 respectively. The L/P value of pathological changes group and normal group of older

Does patella lowering improve crouch gait in cerebral palsy? Comparative retrospective study.

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Desailly, E; Thévenin-Lemoine, C; Khouri, N

2017-09-01

Patella lowering aims to improve quadriceps function as a means of correcting crouch gait in patients with cerebral palsy. Few studies have assessed the effects of patella lowering as a component of multilevel surgery. Including patella lowering into the components of multilevel surgery is beneficial in patients with crouch gait and patella alta. In 12 lower limbs with patella alta (Caton-Deschamps index>1.4) in 41 children with cerebral palsy, patella lowering was performed, without distal femoral extension osteotomy or hamstring release. Among limbs with similar surgical procedures (e.g., hamstring lengthening, rectus femoris transfer) except for patella lowering, controls were selected retrospectively by matching on a propensity score for patella lowering. The propensity score was computed based on preoperative knee flexion contracture, knee extension lag, and minimum knee flexion at mid-stance. Clinical and 3D kinematic data were compared between the two groups. The improvement in minimum knee flexion at mid-stance was significantly greater in the group with patellar lowering (-24°±12°vs. -12°±7°). The Gait Deviation Index improved similarly in the two groups. Knee flexion contracture improved only in the group with patellar lowering. Extension lag did not improve in either group. Peak knee flexion during the swing phase remained unchanged in both groups. Patellar lowering is effective in diminishing minimum knee flexion at mid-stance in patients with patella alta and crouch gait due to cerebral palsy. Patellar lowering has not adverse effects on gait. These findings cannot be assumed to apply to patients with normal patellar height. IV (retrospective study). Copyright © 2017. Published by Elsevier Masson SAS.

An Atypical Variant of Superolateral Dislocation of the Mandibular Condyle: A Case Report.

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Malik, Kapil; Debnath, Subhas C; Adhyapok, Apurba K; Hazarika, Kriti

2017-10-01

Dislocation of the mandibular condyle from the glenoid fossa can occur in anterior, posterior, lateral, and superior directions. Posterior, lateral, and superior dislocations are rare. Superolateral dislocation is seldom encountered in clinical practice. It is generally associated with fracture of the anterior or contralateral side of the mandible. The occurrence of superolateral dislocation of the condyle hooked above the zygomatic arch with an associated fracture of the medial pole of the condyle is rare and has been reported only once in the literature. This report describes another case in which the patient had superolateral dislocation of the mandibular condyle with a fractured medial pole without any associated fracture of the anterior or contralateral side of the mandible. The condyle was hooked laterally above the zygomatic arch. Open reduction of the dislocated condyle was performed and a good outcome was obtained. Copyright © 2017 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Chondrosarcoma of the patella: A case report.

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Ye, Conglin; Luo, Zhiping; Zeng, Jin; Dai, Min

2017-09-01

Chondrosarcoma, characterized by the production of cartilage matrix, is a common bone tumor, accounting for 20% to 27% of all malignant bone tumors. It often occurs in the cartilage of the pelvis, femur, tibia, and humerus. However, chondrosarcoma of the patella is extremely rare. The present study describes a case of chondrosarcoma affecting the right patella in a 68-year-old woman. The chief complaints were painful swelling and limitation of motion of the right knee for about half a year. The pain was a kind of dull ache. The skin around the right knee was red and hot. Moreover, she had a claudication gait due to the symptoms. Irregular lytic lesions with ill-defined margins in the patella were determined through computed tomography and magnetic resonance imaging. The diagnosis of primary grade II chondrosarcoma was finally confirmed on the basis of postoperative pathological examination. The patient underwent an open surgery named extensive resection of patellar tumor to remove the tumor tissue completely. The patient was discharged without any complications 1 week after the surgery. At the 3-month follow-up, the patient was completely free from pain during daily activities, and normal range of motion of the right knee was achieved. Her gait was normal. There was no evidence of recurrence. We believe that an extensive resection is suitable for treating chondrosarcoma to avoid as far as possible local recurrence. An awareness of the potential for chondrosarcoma to present in the patella is crucial for both orthopedic surgeons and radiologists when confronted with similar cases. Besides, as reports of chondrosarcoma of the patella are rare, this study adds a better understanding of this rare condition to the medical literature.

Collagen crosslinks in chondromalacia of the patella.

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Väätäinen, U; Kiviranta, I; Jaroma, H; Arokosi, J; Tammi, M; Kovanen, V

1998-02-01

The aim of the study was to determine collagen concentration and collagen crosslinks in cartilage samples from chondromalacia of the patella. To study the extracellular matrix alterations associated to chondromalacia, we determined the concentration of collagen (hydroxyproline) and its hydroxylysylpyridinoline and lysylpyridinoline crosslinks from chondromalacia foci of the patellae in 12 patients and 7 controls from apparently normal cadavers. The structure of the collagen network in 8 samples of grades II-IV chondromalacia was examined under polarized light microscopy. The full-thickness cartilage samples taken with a surgical knife from chondromalacia lesions did not show changes in collagen, hydroxylysylpyridinoline and lysylpyridinoline concentration as compared with the controls. Polarized light microscopy showed decreased birefringence in the superficial cartilage of chondromalacia lesions, indicating disorganization or disappearance of collagen fibers in this zone. It is concluded that the collagen network shows gradual disorganization with the severity of chondromalacia lesion of the patella without changes in the concentration or crosslinks of collagen.

Atraumatic patellar prosthesis dislocation with patellar tendon injury following a total knee arthroplasty: a case report

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Singh Alka

2010-01-01

Full Text Available Abstract Introduction Total knee arthroplasty is a well-established procedure with gratifying results. There is no consensus in the literature whether to routinely resurface the patella while performing total knee arthroplasty or not. Although an extremely rare occurrence in clinical practice, patellar prosthesis dislocation is a possible complication resulting from total knee arthroplasty. Case presentation We report a rare case of atraumatic spontaneous dislocation of patellar prosthesis in a 63-year-old Caucasian man of British origin with patellar tendon injury. The patient was treated successfully through a revision of the patellar component and tendon repair. In two years follow-up the patient is asymptomatic with no sign of loosening of his patellar prosthesis. Conclusions A thorough understanding of knee biomechanics is imperative in performing total knee arthroplasty in order to achieve a better functional outcome and to prevent early prosthetic failure.

Kinematic MR imaging of the knee for evaluating patellar tracking

International Nuclear Information System (INIS)

Shellock, F.G.; Mink, J.H.; Fox, J.

1988-01-01

A new technique to evaluate patellar tracking uses MR imaging and a specially designed positioning device (MEDRAD). T1-weighted, axial plane imaging was performed on both knees at the following joint angles: 0 0 , 5 0 , 10 0 , 15 0 , 20 0 , 25 0 , and 30 0 . The total examination time was approximately 12 minutes. Images were viewed in a cine loop to produce a kinematic study that depicted the relationship of the patella to the trochlear groove during the different angles of knee flexion. To date, 102 subjects (204 knees) have been examined. Dislocation, subluxatino, lateral tilt, lateral and medial displacement of the patella, and normal patellar tracking could all be identified with this technique. Abnormal configurations of the patella and/or trochlear groove were also clearly demonstrated. In conclusion, kinematic MR imaging of the knee provided important clinical information concerning patellar tracking and other related abnormalities of the patellofemoral joint

Apparently normal accumulation in the patellae on bone scintigraphy

International Nuclear Information System (INIS)

Kato, Katsuhiko; Ikeda, Mitsuru; Tadokoro, Masanori; Yoshida, Kiyo; Kobayashi, Hidetoshi; Ishigaki, Takeo

1997-01-01

In the present study, we examined the influences of gender and ages on accumulation in the patellae on scintigram. The subjects were 828 patients who underwent bone scintigraphy during the past one and half years at the Department of Radiology, Nagoya University Hospital. Patients younger than 20 years old and those with abnormality of the patellae were excluded. The degree of accumulation in the patellae was evaluated using the A-P whole body scintigraphy in comparison with accumulation at the diaphysis of the femur and classified to two categories, ''Positive'' (higher accumulation than that of the diaphysis of the femur) and ''Negative'' (equal or lower than that of the diaphysis of the femur). In general, the degree of accumulation was higher in females than in males. In both males and females, the degree of accumulation increased with age. A difference between the two sides in the degree of accumulation in the patellae was observed in 32% of subjects. The results of this study may serve as basic data for the interpretation of bone scintigrams. (author)

Result of Surgical Treatment of Pseudoarthrosis of the Patella ...

African Journals Online (AJOL)

We noted 2 cases of osteopenia of the patella, a patellofemoral arthrosis in 4 cases, and a lower post operative patella in every patient with an average index of Caton- Deschamps at 0.34 cm (From 0.15 to 0.51 cm) were observed. Two malunion of fractures and an amyotrophy compared with healthy thigh were observed.

[Selective training of the vastus medialis muscle using electrical stimulator for chondromalacia patella].

Science.gov (United States)

Guo, K; Ye, Q; Lin, J; Shen, J; Yang, X

1996-04-01

Chondromalacia patella is closely related with subluxation and tilt of patella, as well as with muscular atrophy of quadriceps, especially in vastus medialis muscle. 364 cases of chondromalacia patella were treated with selective training of the vastus medialis muscle using electrical stimulator in our hospital. 211 cases were followed up after treatment from 6 months to 3 years. Among them excellent and good results were seen in 130 cases (62%), fair results were seen in 69 cases (33%) and no change was seen in 12 cases (5%). Significant reduction of CA (P chondromalacia patella.

Compound transstyloid, transscaphoid, perilunate fracture dislocation

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Nadeem Ali

2013-01-01

Full Text Available Compound fracture dislocations of proximal carpal bones are very rare. We report a 26-year-old male, Defense personnel by profession, who sustained a compound Gustilo Anderson type IIIA transstyloid, transscaphoid, perilunate dislocation. The patient underwent primary proximal row carpectomy and stabilization with uni-planar, uni-lateral external fixator, and K-Wires. On follow-up after a year, the patient had almost negligible range of motion around wrist without any significant discomfort.

Ipsilateral femoral shaft and vertical patella fracture: a case report

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Ozkan, Korhan; Eceviz, Engin; Sahin, Adem; Ugutmen, Ender

2009-01-01

Introduction A femoral shaft fracture with an ipsilateral patella fracture has been, to our knowledge, given only cursory attention in English-speaking literature. Case presentation A 15 year old male patient had hitten by a car to his motorcycle came to emergency room and he had been operated for his femoral shaft freacture and vertical patellar fracture which was iniatally missed. Conclusion To us it is vital to obtain CT scan of the patient’s knee if there is an ipsilateral femoral fracture with an ipsilateral knee effusion and a punction which reveals hematoma even in the absence of a fracture line seen in AP and lateral projections. PMID:19829933

Chondroblastoma of the Patella Treated With Curettage And Bone Graft:A Case Report

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Khodamorad Jamshidi

2011-07-01

Full Text Available Patella is a relative uncommon site for chondroblastoma. Most of cases of chondroblastoma in patella reported in literature are treated with patellectomy. We treated a large chondroblastic lesion in patella of an 18- year-old male with curettage, burring & bone graft and the result was satisfactory after 3 years post operation.

Anatomy, morphology and evolution of the patella in squamate lizards and tuatara (Sphenodon punctatus).

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Regnault, Sophie; Jones, Marc E H; Pitsillides, Andrew A; Hutchinson, John R

2016-05-01

The patella (kneecap) is the largest and best-known of the sesamoid bones, postulated to confer biomechanical advantages including increasing joint leverage and reinforcing the tendon against compression. It has evolved several times independently in amniotes, but despite apparently widespread occurrence in lizards, the patella remains poorly characterised in this group and is, as yet, completely undescribed in their nearest extant relative Sphenodon (Rhynchocephalia). Through radiography, osteological and fossil studies we examined patellar presence in diverse lizard and lepidosauromorph taxa, and using computed tomography, dissection and histology we investigated in greater depth the anatomy and morphology of the patella in 16 lizard species and 19 Sphenodon specimens. We have found the first unambiguous evidence of a mineralised patella in Sphenodon, which appears similar to the patella of lizards and shares several gross and microscopic anatomical features. Although there may be a common mature morphology, the squamate patella exhibits a great deal of variability in development (whether from a cartilage anlage or not, and in the number of mineralised centres) and composition (bone, mineralised cartilage or fibrotendinous tissue). Unlike in mammals and birds, the patella in certain lizards and Sphenodon appears to be a polymorphic trait. We have also explored the evolution of the patella through ancestral state reconstruction, finding that the patella is ancestral for lizards and possibly Lepidosauria as a whole. Clear evidence of the patella in rhynchocephalian or stem lepidosaurian fossil taxa would clarify the evolutionary origin(s) of the patella, but due to the small size of this bone and the opportunity for degradation or loss we could not definitively conclude presence or absence in the fossils examined. The pattern of evolution in lepidosaurs is unclear but our data suggest that the emergence of this sesamoid may be related to the evolution of secondary

Clinical and radiographic features, treatment and outcome in 15 horses with fracture of the medial aspect of the patella

International Nuclear Information System (INIS)

Dyson, S.; Wright, I.; Kold, S.; Vatistas, N.

1992-01-01

A sagittal fracture of the medial aspect of the patella was identified in 15 horses, 2 of which had been kicked and 12 of which had hit a fixed fence while jumping. Eight horses showed concurrent fragmentation of the base of the patella, and 2 had sustained a concurrent fracture of the distal end of the lateral trochlear ridge of the femur. A cranioproximal-craniodistal oblique radiographic view was essential to identify the site of the medial patellar fracture and to determine its configuration. Fourteen horses were treated by surgical removal of the medial patellar fracture fragment(s). Of 12 horses (83%) without evidence of pre-existing degenerative joint disease, 10 were treated successfully with return to full athletic function

Posterior defects of the patella on CT arthrograms

International Nuclear Information System (INIS)

Lehner, K.; Reiser, M.; Hawe, W.; Smasal, V.; Technische Univ. Muenchen; Technische Univ. Muenchen

1986-01-01

Changes of the posterior bony and cartilaginous surfaces of the patella as seen on CT arthrograms are described in the case of bipartite patellae, fractures and ossification defects. Contrary to present opinion, cartilaginous lesions are frequently seen on CT arthrograms. This is also true for discreet and partial ossification defects which are not visible on conventional X-rays and are described here for the first time. The aetiology, morphogenesis and clinical examples are discussed. (orig.) [de

Articular cartilage changes in chondromalacia patellae.

Science.gov (United States)

Bentley, G

1985-11-01

Full thickness samples of articular cartilage were removed from areas of chondromalacia on the medial and "odd" facets of the patellae of 21 adults and examined by histology, autoradiography and electron microscopy. Surface fibrillation, loss of superficial matrix staining and reduced 35SO4 labelling was seen, with little change in the deep zone. Ten cases showed "fibrous metaplasia" of the superficial cartilage with definite evidence of cell division and apparent smoothing of the surface. Scattered chondrocyte replication appeared to occur in the surrounding intact cartilage. The findings suggest that early lesions in chondromalacia patellae may heal either by cartilage or fibrous metaplasia and that this may account for the resolution of clinical symptoms.

Biologic resurfacing of the patella bone versus patellectomy

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Motamedi M

1995-04-01

Full Text Available In the past years, there was a tendency to excise the patella in pathologic conditions affecting this bone. The patella has many critical effects in the function of the knee joint. For example, after its exicision the force of quadriceps muscle decreases by forty percent (40% and the knee joint becomes prone to early osteoarthritic changes. For these reasons, in the recent years the "biologic resurfacing of patella" has been used in pathologic conditions instead of its complete removal. In this new method after resection of the diseased part of the bone, the fascia of the quadriceps muscle, with its intact base, is used to cover the resected part of the bone. In practice, after pain relief, the active motion of the joint is started. Then the limb is placed in a splint or brace and after a period of 3 weeks, passive motion is begun.

Oxidized zirconium versus cobalt-chromium against the native patella in total knee arthroplasty: Patellofemoral outcomes.

Science.gov (United States)

Matassi, Fabrizio; Paoli, Tommaso; Civinini, Roberto; Carulli, Christian; Innocenti, Massimo

2017-10-01

Oxidized zirconium (OxZr) has demonstrated excellent mechanical properties in vitro when used against articular cartilage; less coefficient of friction and less chondral damage have been found when compared with cobalt-chromium (CoCr) implants. However, controversy exists as to whether implants with a zirconium femoral component articulate safely with a native patella in total knee arthroplasty (TKA). To answer this question, the clinical and radiographic results were analysed from a group of patients who underwent a TKA with patella retention; the OxZr versus CoCr femoral components were compared. The present study prospectively evaluated 83 knees of 74 patients from 2009 to 2010. Each patient was evaluated clinically (visual analogue scale, Knee Society score, patellar score) and radiographically (long leg standing radiograph, anterior-posterior and latero-lateral projections, axial view of the patella) pre-operatively and postoperatively with a mean follow-up of 4.47years. The patellar tilt and shift, and progression of patellofemoral osteoarthritis were calculated with the axial view. There were no patient reported adverse reactions and none of the evaluated prostheses failed. Both the clinical and radiographic evaluations showed no statistically significant between-group differences. No adverse events were observed clinically or radiologically. These results justify pursuing the use of oxidized zirconium as an alternative bearing surface for a femoral component associated with patellar retention in TKA. Published by Elsevier B.V.

Chondromalacia patellae: diagnosis with MR imaging.

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McCauley, T R; Kier, R; Lynch, K J; Jokl, P

1992-01-01

Most previous studies of MR imaging for detection of chondromalacia have used T1-weighted images. We correlated findings on axial MR images of the knee with arthroscopic findings to determine MR findings of chondromalacia patellae on T2-weighted and proton density-weighted images. The study population included 52 patients who had MR examination of the knee with a 1.5-T unit and subsequent arthroscopy, which documented chondromalacia patellae in 29 patients and normal cartilage in 23. The patellar cartilage was assessed retrospectively for MR signal and contour characteristics. MR diagnosis based on the criteria of focal signal or focal contour abnormality on either the T2-weighted or proton density-weighted images yielded the highest correlation with the arthroscopic diagnosis of chondromalacia. When these criteria were used, patients with chondromalacia were detected with 86% sensitivity, 74% specificity, and 81% accuracy. MR diagnosis based on T2-weighted images alone was more sensitive and accurate than was diagnosis based on proton density-weighted images alone. In conclusion, most patients with chondromalacia patellae have focal signal or focal contour defects in the patellar cartilage on T2-weighted MR images. These findings are absent in most patients with arthroscopically normal cartilage.

Isolated Proximal Tibiofibular Dislocation during Soccer

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Casey Chiu

2015-01-01

Full Text Available Proximal tibiofibular dislocations are rarely encountered in the Emergency Department (ED. We present a case involving a man presenting to the ED with left knee pain after making a sharp left turn on the soccer field. His physical exam was only remarkable for tenderness over the lateral fibular head. His X-rays showed subtle abnormalities of the tibiofibular joint. The dislocation was reduced and the patient was discharged from the ED with orthopedic follow-up.

The ''hot'' patella

International Nuclear Information System (INIS)

Kipper, M.S.; Alazraki, N.P.; Feiglin, D.H.

1982-01-01

Increased patellar uptake on bone scans is seen quite commonly but the possible or probable etiologies of this finding have not been previously well described. A review of 100 consecutive bone scans showed that the incidence of bilateral ''hot'' patellae is 15%. Identified etiologies include osteoarthritic degenerative disease (35%), fracture, possible metastatic disease, bursitis, Paget's disease, and osteomyelitis. The value of careful history, physical examination, and radiographs is stressed

Ewing's sarcoma of the patella.

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Gorelik, Natalia; Dickson, Brendan C; Wunder, Jay S; Bleakney, Robert

2013-05-01

Ewing's sarcoma is a relatively rare malignancy, occurring mainly between 4 and 25 years of age. It usually arises from the pelvis, followed by the femur, tibia, and remainder of both the long bones of the extremities and flat bones of the axial skeleton. To the best of our knowledge, Ewing's sarcoma of the patella has never been reported previously. Patellar tumors occur infrequently and represent an uncommon etiology of anterior knee pain. We describe the rare case of a 41-year-old man who presented with a 3-4 month history of escalating right anterior knee pain and swelling. Imaging demonstrated an aggressive patellar tumor with an adjacent soft tissue mass. The diagnosis of Ewing's sarcoma was confirmed by pathology. Physicians should be aware of atypical locations for Ewing's sarcoma and, conversely, of rare tumors arising in the patella and accounting for anterior knee pain. Early recognition of such malignancies allows prompt initiation of treatment, hence improving prognosis.

Dislocation confinement in the growth of Na flux GaN on metalorganic chemical vapor deposition-GaN

International Nuclear Information System (INIS)

Takeuchi, S.; Asazu, H.; Nakamura, Y.; Sakai, A.; Imanishi, M.; Imade, M.; Mori, Y.

2015-01-01

We have demonstrated a GaN growth technique in the Na flux method to confine c-, (a+c)-, and a-type dislocations around the interface between a Na flux GaN crystal and a GaN layer grown by metalorganic chemical vapor deposition (MOCVD) on a (0001) sapphire substrate. Transmission electron microscopy (TEM) clearly revealed detailed interface structures and dislocation behaviors that reduced the density of vertically aligned dislocations threading to the Na flux GaN surface. Submicron-scale voids were formed at the interface above the dislocations with a c component in MOCVD-GaN, while no such voids were formed above the a-type dislocations. The penetration of the dislocations with a c component into Na flux GaN was, in most cases, effectively blocked by the presence of the voids. Although some dislocations with a c component in the MOCVD-GaN penetrated into the Na flux GaN, their propagation direction changed laterally through the voids. On the other hand, the a-type dislocations propagated laterally and collectively near the interface, when these dislocations in the MOCVD-GaN penetrated into the Na flux GaN. These results indicated that the dislocation propagation behavior was highly sensitive to the type of dislocation, but all types of dislocations were confined to within several micrometers region of the Na flux GaN from the interface. The cause of void formation, the role of voids in controlling the dislocation behavior, and the mechanism of lateral and collective dislocation propagation are discussed on the basis of TEM results

Chondromalacia patellae treated by warming needle and rehabilitation training.

Science.gov (United States)

Qiu, Ling; Zhang, Min; Zhang, Ji; Gao, Le-Nv; Chen, Da-wei; Liu, Jun; She, Jia-yi; Wang, Ling; Yu, Jin-yan; Huang, Le-ping; Bai, Yang

2009-06-01

To observe the effect of warming needle combined with rehabilitation training on chondromalacia patellae in a randomized controlled trial. The 92 cases were randomly divided into a treatment group treated by warming needle plus rehabilitation training (47 cases) and a control group treated by medication plus rehabilitation training (45 cases), and the therapeutic effect was compared after 20 sessions. The pain was relieved more obviously in the treatment group than in the control group (P chondromalacia patellae.

Evaluation of chondromalacia of the patella with axial inversion recovery-fast spin-echo imaging.

Science.gov (United States)

Lee, S H; Suh, J S; Cho, J; Kim, S J; Kim, S J

2001-03-01

The purpose of our study was to assess the accuracy of inversion recovery-fast spin-echo (IR-FSE) imaging for the evaluation of chondromalacia of the patella. Eighty-six patients were included, they underwent magnetic resonance (MR) examination and subsequent knee arthroscopy. Medial and lateral facets of the patella were evaluated separately. Axial images were obtained by using IR-FSE (TR/TE/TI = 3000/25/150 msec; echo train length, 8; 4-mm thickness; 12-cm field of view; 512 x 256 matrix; two, number of excitations) with a 1.5-T MR machine. MR interpretation of chondromalacia was made on the basis of the arthroscopic grading system. Of a total of 172 facets graded, arthroscopy revealed chondromalacia in 14 facets with various grades (G0, 158; G1, 1; G2, 3; G3, 6; G4, 4). Sensitivity, specificity, and accuracy in the chondromalacia grades were 57.1%, 93.0%, and 90.1%, respectively. There was one false-negative case (G4) and 11 false-positive cases (G1, eight; G2, two; G3, one). Sensitivity and specificity corrected by one grade difference were improved to 85.7% and 98.1%, respectively. When cartilage changes were grouped into early (corresponding to grade 1 and 2) and advanced (grade 3 and 4) diseases, sensitivity and specificity of the early and advanced diseases were 75% and 94% and 80% and 99%, respectively. IR-FSE imaging of the knee revealed high specificity but low sensitivity for the evaluation of chondromalacia of the patella.

Is Electrocautery of Patella Useful in Patella Non-Resurfacing Total Knee Arthroplasty?: A Prospective Randomized Controlled Study.

Science.gov (United States)

Kwon, Sae Kwang; Nguku, Levis; Han, Chang Dong; Koh, Yong-Gon; Kim, Dong-Wook; Park, Kwan Kyu

2015-12-01

There is controversy over the need for electrocauterization of the patella in non-resurfacing total knee arthroplasty (TKA). We investigated whether this procedure is beneficial through a prospective randomized controlled trial. Fifty patients who underwent electrocautery were compared with 50 patients who did not undergo this procedure. We determined cartilage status, preoperative and postoperative American Knee Society (AKS) score, the Western Ontario and McMaster Universities score (WOMAC) and the Patellofemoral (PF) scores for a minimum of 5 years. The two groups did not differ significantly in demographics, intraoperative cartilage status, or preoperative or postoperative outcomes. No complications were detected in either group. We found no benefits of electrocautery of the patella in patellar non-resurfacing TKA up to 5 years. Copyright © 2015 Elsevier Inc. All rights reserved.

THE INFLUENCE OF THE SURGICAL APPROACH CONCERNING DISLOCATION IN TOTAL HIP ARTHROPLASTY.

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Vicente, José Ricardo Negreiros; Pires, André Fernandes; Lee, Bruno Takasaki; Leonhardt, Marcos Camargo; Ejnisman, Leandro; Croci, Alberto Tesconi

2009-01-01

Our primary aim was to evaluate the occurrence of dislocation of non-cemented total hip arthroplasty, when using the posterior and the direct lateral approaches. We performed a comparative retrospective study with 232 patients submitted to non-cemented total hip arthroplasty, due to the diagnosis of primary or secondary osteoarthritis. The posterior approach was used in 105 patients while direct lateral approach was used in 127 patients. There was only one prosthesis model and the same rehabilitation program and post-operative care was used for all patients. We checked the occurrence of dislocation, the acetabular positioning and also the size of the components. There was only one case of dislocation, treated with closed reduction successfully. This was a 47 year-old female, submitted to direct lateral approach. The mean follow-up time for both groups was 23.7 months, ranging from six to 42 months. The authors conclude that the prevalence of total hip arthroplasty dislocation is similar for both approaches, and educational measures besides the use of a higher femoral offset seem to reduce the risk of this complication.

Increased serum cartilage oligomeric matrix protein levels and decreased patellar bone mineral density in patients with chondromalacia patellae.

Science.gov (United States)

Murphy, E; FitzGerald, O; Saxne, T; Bresnihan, B

2002-11-01

Chondromalacia patellae is a potentially disabling disorder characterised by features of patellar cartilage degradation. To evaluate markers of cartilage and bone turnover in patients with chondromalacia patellae. 18 patients with chondromalacia patellae were studied. Serum cartilage oligomeric matrix protein (s-COMP) and bone sialoprotein (s-BSP) levels were measured by enzyme linked immunosorbent assay (ELISA) and compared with those of age and sex matched healthy control subjects. Periarticular bone mineral density (BMD) of both knee joints was assessed by dual energy x ray absorptiometry (DXA). s-COMP levels were significantly raised in all patients with chondromalacia patellae compared with healthy control subjects (p=0.0001). s-BSP levels did not differ significantly between the groups (p=0.41). BMD of the patella was significantly reduced in patients with chondromalacia patellae compared with the control subjects (p=0.016). In patients with bilateral chondromalacia patellae, BMD of the patella was lower in the more symptomatic knee joint (p=0.005). Changes in periarticular BMD were localised to the patella and were not present in femoral regions. Neither s-COMP (p=0.18) nor s-BSP (p=0.40) levels correlated with patellar BMD. Increased s-COMP levels, reflecting cartilage degradation, and reduced BMD localised to the patella may represent clinically useful markers in the diagnosis and monitoring of patients with chondromalacia patellae. Measures of cartilage degradation did not correlate with loss of patellar bone density, suggesting dissociated pathophysiological mechanisms.

Patellofemoral Arthralgia, Overuse Syndromes of the Knee, and Chondromalacia Patella

OpenAIRE

Welsh, R. Peter

1985-01-01

Patellofemoral arthralgia is a very common syndrome affecting athletes. Most often, examination fails to define true pathology. Conservative treatment, an active exercise program, and sports may be undertaken without harm to the knee. The patellofemoral arthralgia syndrome must be differentiated from true chondromalacia patella, where there is actual degeneration of the patella's articular cartilage, and from other sources of internal derangement such as meniscal disease or osteochondral lesi...

Temporomandibular joint dislocation due to acute propranolol intoxication

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Abbas Aghabiklooei

2010-07-01

Full Text Available Abbas Aghabiklooei1, Homan Elahi2, Babak Mostafazadeh31Department of Medical Toxicology and Forensic Medicine, Iran University of Medical Sciences, Tehran, Iran; 2Firouzgar Hospital, Department of ENT, Tehran, Iran; 3Department of Medical Toxicology and Forensic Medicine, Shaheed Beheshty University of Medical Sciences, Tehran, IranAbstract: Temporomandibular joint (TMJ dislocation has not previously been reported as a complication of beta-blocker toxicity. We are reporting two cases of TMJ dislocation resulted from acute severe intoxication with pure propranolol (PPL for the first time. Bilateral TMJ dislocation happened in two patients who were admitted to intensive care unit with diagnosis of severe acute PPL toxicity. Clinical diagnosis of TMJ dislocation was obtained by physical examination. Successful reduction was performed for both patients without subsequent recurrence in two weeks following hospital discharge. Both of our subjects had no previous history of lower jaw dislocation. There was not any risk factor for dislocation such as convulsion during admission period, recent face trauma, or oral manipulation by the medical team. This study showed that TMJ dislocation may occur after severe acute PPL toxicity probably due to spastic contraction of the lateral pterygoid muscle. This is against previously mentioned hypothesis that stated masseteric muscles contraction as the main cause of a bilateral dislocated TMJ.Keywords: propranolol, toxicity, temporomandibular joint dislocation

A new MRI grading system for chondromalacia patellae.

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Özgen, Ali; Taşdelen, Neslihan; Fırat, Zeynep

2017-04-01

Background Chondromalacia patellae is a very common disorder. Although magnetic resonance imaging (MRI) is widely used to investigate patellar cartilage lesions, there is no descriptive MRI-based grading system for chondromalacia patellae. Purpose To propose a new MRI grading system for chondromalacia patellae with corresponding high resolution images which might be useful in precisely reporting and comparing knee examinations in routine daily practice and used in predicting natural course and clinical outcome of the patellar cartilage lesions. Material and Methods High resolution fat-saturated proton density (FS PD) images in the axial plane with corresponding T2 mapping images were reviewed. A detailed MRI grading system covering the deficiencies of the existing gradings has been set and presented on these images. Two experienced observers blinded to clinical data examined 44 knee MR images and evaluated patellar cartilage changes according to the proposed grading system. Inter- and intra-rater validity testing using kappa statistics were calculated. Results A descriptive and detailed grading system with corresponding FS PD and T2 mapping images has been presented. Inter-rater agreement was 0.80 (95% confidence interval [CI], 0.71-0.89). Intra-rater agreements were 0.83 (95% CI, 0.74-0.91) for observer A and 0.79 (95% CI, 0.70-0.88) for observer B (k-values). Conclusion We present a new MRI grading system for chondromalacia patellae with corresponding images and good inter- and intra-rater agreement which might be useful in reporting and comparing knee MRI examinations in daily practice and may also have the potential for using more precisely predicting prognosis and clinical outcome of the patients.

Decreased torque and electromyographic activity in the extensor thigh muscles in chondromalacia patellae.

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Väätäinen, U; Airaksinen, O; Jaroma, H; Kiviranta, I

1995-01-01

The alterations in thigh muscle properties of chondromalacia patellae patients during isometric and dynamic endurance tests were studied using a variokinetic knee testing system linked to surface EMG. A total of 41 patients (chondromalacia group) with arthroscopically certified chondromalacia of the patella were studied. The control group consisted of 31 healthy adult volunteers with no history of knee pain or trauma. Peak torque values were 21% (p chondromalacia group than in the control group. The decrease in the ratio between integrated EMG (IEMG) and measured force were found in all parts of the quadriceps femoris muscle in patients with chondromalacia of the patella in isometric extension. No change in the normalized IEMG levels of the thigh muscles were found between chondromalacia patients and controls in dynamic endurance test. The severity of the chondromalacia of the patella did not affect the level of electromyographic activation in thigh muscles. The ratio of normalized EMG levels of vastus medialis and vastus lateralis did not differ between the groups. The present study showed that chondromalacia patellae patients have reduced force and electromyographic activation levels of quadriceps femoris muscle. Especially, the explosive strength of the quadriceps femoris muscle is reduced.

Early osteoarthritis of the patellofemoral joint.

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Arendt, Elizabeth A; Berruto, Massimo; Filardo, Giuseppe; Ronga, Mario; Zaffagnini, Stefano; Farr, Jack; Ferrua, Paolo; Grassi, Alberto; Condello, Vincenzo

2016-06-01

Patellofemoral joint cartilage lesions are associated with a variety of clinical situations including blunt trauma, lateral patella dislocations, or as a secondary development in the setting of abnormal joint loading. There is a need for more clarity on how to best address these lesions. Most specifically, when is it necessary to surgically treat these lesions of the patella and trochlea and which technique to use? This review will focus on the spectrum of patellofemoral disease/injury and their treatment strategies, with special emphasis on cartilage damage and early osteoarthritis. Chapter sections will review the most common scenarios of cartilage damage in the patellofemoral joint, with an attempt to summarize current treatment, their outcomes, remaining challenges and unanswered questions.

Unicameral bone cyst of the patella in a young dog.

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Petazzoni, M; Briotti, F; Beale, B

2015-01-01

This report describes a case of a solitary unicameral patellar bone cyst in a young dog. A five-month-old, male Dobermann Pinscher dog was referred for a 10-day left hindlimb lameness. A mild swelling of the peripatellar soft tissues of the left patella was detected upon physical examination. Signs of pain were elicited upon direct palpation of the patella. Radiographic examination revealed an oval radiolucency within the medullary cavity at the base of the left patella. Radiographic examination, arthroscopy, and histopathology findings supported the diagnosis of a benign patellar bone cyst. The condition was treated by surgical curettage and autogenous bone graft harvested from the ipsilateral proximal tibia. Clinical signs, including lameness and signs of pain upon deep palpation, disappeared three weeks after surgery. Follow-up re-evaluation five years after surgery revealed no recurrence of the cyst and the patient was asymptomatic.

Magnetic resonance findings in knee dislocation: pictorial essay

International Nuclear Information System (INIS)

Coates, M.; Stewart, N.; Morganti, V.; Twaddle, B.

2000-01-01

The role of MRI in the preoperative assessment of knee dislocation is well documented. e present our experience with a series of images graphically displaying the spectrum of abnormalities associated with these injuries. These images were derived from a local internal audit reviewing the preoperative MRI and correlating this with the surgical findings. Twenty-two cases between April 1997 and April 1999 were reviewed. Traumatic dislocation of the knee is rare, although many believe it is often unrecognized because of spontaneous reduction.' The injury may present as (i) frank dislocation; (ii) a knee that is dislocated while under anaesthesia; or (iii) a pattern of soft-tissue injury which suggests dislocation. Dislocation is described by the position of the tibia relative to the femur and may be anterior, posterior, lateral, medial or rotatory. Conservative management has traditionally been advocated and in this setting clinical examination and plain radiographs are adequate. Because of the trend toward increased surgical intervention, however, the more accurate characterization of soft-tissue injuries provided by MRI aids the planning of ligamentous reconstruction and the operative approach. Copyright (1999) Blackwell Science Pty Ltd

Reliability of clinical findings and magnetic resonance imaging for the diagnosis of chondromalacia patellae.

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Pihlajamäki, Harri K; Kuikka, Paavo-Ilari; Leppänen, Vesa-Veikko; Kiuru, Martti J; Mattila, Ville M

2010-04-01

This diagnostic study was performed to determine the correlation between anterior knee pain and chondromalacia patellae and to define the reliability of magnetic resonance imaging for the diagnosis of chondromalacia patellae. Fifty-six young adults (median age, 19.5 years) with anterior knee pain had magnetic resonance imaging of the knee followed by arthroscopy. The patellar chondral lesions identified by magnetic resonance imaging were compared with the arthroscopic findings. Arthroscopy confirmed the presence of chondromalacia patellae in twenty-five (45%) of the fifty-six knees, a synovial plica in twenty-five knees, a meniscal tear in four knees, and a femorotibial chondral lesion in four knees; normal anatomy was seen in six knees. No association was found between the severity of the chondromalacia patellae seen at arthroscopy and the clinical symptoms of anterior knee pain syndrome (p = 0.83). The positive predictive value for the ability of 1.0-T magnetic resonance imaging to detect chondromalacia patellae was 75% (95% confidence interval, 53% to 89%), the negative predictive value was 72% (95% confidence interval, 56% to 84%), the sensitivity was 60% (95% confidence interval, 41% to 77%), the specificity was 84% (95% confidence interval, 67% to 93%), and the diagnostic accuracy was 73% (95% confidence interval, 60% to 83%). The sensitivity was 13% (95% confidence interval, 2% to 49%) for grade-I lesions and 83% (95% confidence interval, 59% to 94%) for grade-II, III, or IV lesions. Chondromalacia patellae cannot be diagnosed on the basis of symptoms or with current physical examination methods. The present study demonstrated no correlation between the severity of chondromalacia patellae and the clinical symptoms of anterior knee pain syndrome. Thus, symptoms of anterior knee pain syndrome should not be used as an indication for knee arthroscopy. The sensitivity of 1.0-T magnetic resonance imaging was low for grade-I lesions but considerably higher for more

Chondroblastoma patella presenting as a pathological fracture

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Gudi Narayan

2008-01-01

Full Text Available A 24-year-old male presented with an inability to walk after a trivial fall. He had pain and mild swelling anterior to the right knee for the past one year. X-ray showed a transverse fracture of patella with a lytic lesion occupying most of the two halves of the patella. Fine needle aspiration cytology (FNAC of the lytic lesion revealed a few osteoclastic giant cells and occasional osteoblasts against a hemorrhagic background. Patellectomy was performed. Histology revealed trabecular bone admixed with proliferating chondroid tissue at places admixed with myxoid and fibrous tissue with focal areas of calcification suggestive of chondroblastoma. Focal areas showed osteoclastic giant cells with areas of hemorrhage. The purpose is to present a rare tumor occurring at an unusual site which presented as pathological fracture.

Correlation between subcutaneous knee fat thickness and chondromalacia patellae on magnetic resonance imaging of the knee.

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Kok, Hong Kuan; Donnellan, John; Ryan, Davinia; Torreggiani, William C

2013-08-01

Chondromalacia patellae is a common cause of anterior knee pain in young patients and can be detected noninvasively with magnetic resonance imaging (MRI). The purpose of our study was to evaluate the correlation between subcutaneous fat thickness around the knee joint on axial MRIs as a surrogate marker of obesity, with the presence or absence of chondromalacia patellae. A retrospective review was conducted of knee MRIs in 170 patients who satisfied the inclusion criteria. Imaging was performed over a 12-month period on a 1.5T MRI system with a dedicated extremity coil. Two radiologists experienced in musculoskeletal imaging assessed each examination in consensus for the presence or absence of chondromalacia patellae and graded positive studies from 0 (absent) to 3 (full cartilage thickness defect). Measurement of subcutaneous knee fat thickness was obtained on the medial aspect of the knee. MRI findings of chondromalacia patellae were present in 33 patients (19.4%), of which, there were 11 grade 1 lesions (33.3%), 9 grade 2 lesions (27.3%), and 13 grade 3 lesions (39.4%). The mean subcutaneous knee fat thickness was significantly higher in the chondromalacia patellae group for all grades compared with the normal group (P chondromalacia patellae (R = 0.48 [95% confidence interval, 0.38-0.68]; P chondromalacia patellae. Subcutaneous knee fat thickness as a surrogate marker of obesity was positively associated with the presence and severity of chondromalacia patellae on MRI. Copyright © 2013 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

A novel biological approach to treat chondromalacia patellae.

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Pak, Jaewoo; Lee, Jung Hun; Lee, Sang Hee

2013-01-01

Mesenchymal stem cells from several sources (bone marrow, synovial tissue, cord blood, and adipose tissue) can differentiate into variable parts (bones, cartilage, muscle, and adipose tissue), representing a promising new therapy in regenerative medicine. In animal models, mesenchymal stem cells have been used successfully to regenerate cartilage and bones. However, there have been no follow-up studies on humans treated with adipose-tissue-derived stem cells (ADSCs) for the chondromalacia patellae. To obtain ADSCs, lipoaspirates were obtained from lower abdominal subcutaneous adipose tissue. The stromal vascular fraction was separated from the lipoaspirates by centrifugation after treatment with collagenase. The stem-cell-containing stromal vascular fraction was mixed with calcium chloride-activated platelet rich plasma and hyaluronic acid, and this ADSCs mixture was then injected under ultrasonic guidance into the retro-patellar joints of all three patients. Patients were subjected to pre- and post-treatment magnetic resonance imaging (MRI) scans. Pre- and post-treatment subjective pain scores and physical therapy assessments measured clinical changes. One month after the injection of autologous ADSCs, each patient's pain improved 50-70%. Three months after the treatment, the patients' pain improved 80-90%. The pain improvement persisted over 1 year, confirmed by telephone follow ups. Also, all three patients did not report any serious side effects. The repeated magnetic resonance imaging scans at three months showed improvement of the damaged tissues (softened cartilages) on the patellae-femoral joints. In patients with chondromalacia patellae who have continuous anterior knee pain, percutaneous injection of autologous ADSCs may play an important role in the restoration of the damaged tissues (softened cartilages). Thus, ADSCs treatment presents a glimpse of a new promising, effective, safe, and non-surgical method of treatment for chondromalacia patellae.

A Novel Biological Approach to Treat Chondromalacia Patellae

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Lee, Sang Hee

2013-01-01

Mesenchymal stem cells from several sources (bone marrow, synovial tissue, cord blood, and adipose tissue) can differentiate into variable parts (bones, cartilage, muscle, and adipose tissue), representing a promising new therapy in regenerative medicine. In animal models, mesenchymal stem cells have been used successfully to regenerate cartilage and bones. However, there have been no follow-up studies on humans treated with adipose-tissue-derived stem cells (ADSCs) for the chondromalacia patellae. To obtain ADSCs, lipoaspirates were obtained from lower abdominal subcutaneous adipose tissue. The stromal vascular fraction was separated from the lipoaspirates by centrifugation after treatment with collagenase. The stem-cell-containing stromal vascular fraction was mixed with calcium chloride-activated platelet rich plasma and hyaluronic acid, and this ADSCs mixture was then injected under ultrasonic guidance into the retro-patellar joints of all three patients. Patients were subjected to pre- and post-treatment magnetic resonance imaging (MRI) scans. Pre- and post-treatment subjective pain scores and physical therapy assessments measured clinical changes. One month after the injection of autologous ADSCs, each patient's pain improved 50–70%. Three months after the treatment, the patients' pain improved 80–90%. The pain improvement persisted over 1 year, confirmed by telephone follow ups. Also, all three patients did not report any serious side effects. The repeated magnetic resonance imaging scans at three months showed improvement of the damaged tissues (softened cartilages) on the patellae-femoral joints. In patients with chondromalacia patellae who have continuous anterior knee pain, percutaneous injection of autologous ADSCs may play an important role in the restoration of the damaged tissues (softened cartilages). Thus, ADSCs treatment presents a glimpse of a new promising, effective, safe, and non-surgical method of treatment for chondromalacia patellae

A novel biological approach to treat chondromalacia patellae.

Directory of Open Access Journals (Sweden)

Jaewoo Pak

Full Text Available Mesenchymal stem cells from several sources (bone marrow, synovial tissue, cord blood, and adipose tissue can differentiate into variable parts (bones, cartilage, muscle, and adipose tissue, representing a promising new therapy in regenerative medicine. In animal models, mesenchymal stem cells have been used successfully to regenerate cartilage and bones. However, there have been no follow-up studies on humans treated with adipose-tissue-derived stem cells (ADSCs for the chondromalacia patellae. To obtain ADSCs, lipoaspirates were obtained from lower abdominal subcutaneous adipose tissue. The stromal vascular fraction was separated from the lipoaspirates by centrifugation after treatment with collagenase. The stem-cell-containing stromal vascular fraction was mixed with calcium chloride-activated platelet rich plasma and hyaluronic acid, and this ADSCs mixture was then injected under ultrasonic guidance into the retro-patellar joints of all three patients. Patients were subjected to pre- and post-treatment magnetic resonance imaging (MRI scans. Pre- and post-treatment subjective pain scores and physical therapy assessments measured clinical changes. One month after the injection of autologous ADSCs, each patient's pain improved 50-70%. Three months after the treatment, the patients' pain improved 80-90%. The pain improvement persisted over 1 year, confirmed by telephone follow ups. Also, all three patients did not report any serious side effects. The repeated magnetic resonance imaging scans at three months showed improvement of the damaged tissues (softened cartilages on the patellae-femoral joints. In patients with chondromalacia patellae who have continuous anterior knee pain, percutaneous injection of autologous ADSCs may play an important role in the restoration of the damaged tissues (softened cartilages. Thus, ADSCs treatment presents a glimpse of a new promising, effective, safe, and non-surgical method of treatment for chondromalacia

A correlative study between prevalence of chondromalacia patellae and sports injury in 4068 students.

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Zhang, Hui; Kong, Xiang-qing; Cheng, Cong; Liang, Mao-hua

2003-12-01

To study the prevalence of chondromalacia patella among college students and the correlation with sports injury. 354 students from gymnastic department and 429 from nongymnastic department with knee joint pain were selected. 184 students from gymnastic department and 342 from nongymnastic department were checked randomly by a surgeon. 77 patients (37 males, 40 females) from gymnastic department and 119 patients (62 males, 57 females) from nongymnastic department were diagnosed as chondromalacia patellae. The amount of exercise and the occurrence of sports injury were investigated in each student. All data were analyzed with SPSS 10.0 statistical software. The prevalence of chondromalacia patella was 20.1% in female students and 11.6% in male students from gymnastic department, and 5.61% in female students and 4.92% in male students from nongymnastic department. The amount of exercise and the occurrence of sports injury to the knee joint in students from gymnastic department were greater than those from nongymnastic department. In both female and male students, the prevalence of chondromalacia patella is higher in gymnastic department than nongymnastic department. Sports injury is an important cause of chondromalacia patella.

Bone density in patients with chondromalacia patella.

Science.gov (United States)

Salehi, Iraj; Khazaeli, Shabnam; Hatami, Parta; Malekpour, Mahdi

2010-06-01

Chondromalacia of the patella is the most common cause of anterior knee pain in young women. The etiology of the disease is not well-understood but the initial lesion is a disorganization of collagenous structures. Since the disease is proposed to be due to generalized constitutional disturbance, we postulated that bony structures could also be involved. To investigate this hypothesis we measured the bone density of 286 patients with the diagnosis of chondromalacia of the patella during a 4-year period using dual energy X-ray absorptiometry (DXA) method. We found a significant number of patients having low bone densities. This problem was more pronounced in men and in younger age groups. We suggest base-line bone density evaluation in all patients, treatment of osteopenia or osteoporosis in select patients and regular follow-ups using DXA.

Lateral patellar luxation in nine small breed dogs | Dona | Open ...

African Journals Online (AJOL)

The objective of this paper was to describe the clinical features, the management and the outcome of nine small breed dogs affected with lateral patella luxation referred during the period between January 2010 and December 2014. Patellar luxations were classified according to: breed, age, sex, weight, and grade of ...

Medial subtalar dislocation: Case report

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Manojlović Radovan

2010-01-01

Full Text Available Introduction. Subtalar dislocation (SI is a term that refers to an injury in which there is dislocation of the talonavicular and talocalcanear joint, although the tibiotalar joint is intact. Case Outline. A case of medial subtalar dislocation as a result of basketball injury, so-called 'basketball foot', is presented. Closed reposition in i.v. anaesthesia was performed with the patient in supine position and a knee flexed at 90 degrees. Longitudinal manual traction in line of deformity was carried out in plantar flexion. The reposition continued with abduction and eversion simultaneously increasing dorsiflexion. It was made in the first attempt and completed instantly. Rehabilitation was initiated after 5 weeks of immobilization. One year after the injury, the functional outcome was excellent with full range of motion and the patient was symptom-free. For better interpretation of roentgenogram, bone model of subtalar dislocation was made using the cadaver bone. Conclusion. Although the treatment of such injury is usually successful, diagnosis can be difficult because it is a rare injury, and moreover, X-ray of the injury can be confusing due to superposition of bones. Radiograms revealed superposition of the calcaneus, tarsal and metatarsal bones which was radiographically visualized in the anterior-posterior projection as one osseous block inward from the talus, and on the lateral view as in an osteal block below the tibial bone. Prompt recognition of these injuries followed by proper, delicately closed reduction under anaesthesia is crucial for achieving a good functional result in case of medial subtalar dislocation.

[Osteoblastoma of the patella (author's transl)].

Science.gov (United States)

Sicard, A; Touzard, R C; Squalli, S

1979-01-01

Osteoblastoma is a rare bony tumour. Its localisation at the level of the patella seems exceptional. Our case is the third published case. Wide curetage was a failure, and did not permit histological diagnosis. A cure was obtained by patellectomy, after which the diagnosis of the lesion was made without any doubt.

Magnetic resonance imaging of patellofemoral relationships

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Koskinen, S.K. (Dept. of Diagnostic Radiology, Turku Univ. Hospital (Finland)); Taimela, S. (Helsinki Research Inst. for Sports and Exercise Medicine (Finland)); Nelimarkka, O. (Dept. of Surgery, Turku Univ. Hospital (Finland)); Komu, M. (Dept. of Diagnostic Radiology, Turku Univ. Hospital (Finland)); Kujala, U.M. (Helsinki Research Inst. for Sports and Exercise Medicine (Finland))

1993-08-01

Patellofemoral relationships were analyzed in 11 patients (13 knees) with patellar dislocation and 15 asymptomatic subjects (15 knees) at 0 and 20 of flexion. The measurements were made from five consecutive axial images through the patellofemoral joint. The six indices measured were lateral patellar tilt (LPT), lateral patellofemoral angle (LPA), lateral patellar displacement (LPD), patella-lateral condyle index (L/PW), congruence angle (CA), and sulcus angle (SA). The reproducibility of the method was evaluated. The difference between the two study groups was more evident at 0 than at 20 of knee flexion. Significant differences were noted between measurements made at different levels of the joint, particularly in the controls. Isometric contraction of the quadriceps muscle lateralized and tilted the patella slightly in both groups. L/PW with and without quadriceps muscle contraction, and LPA with reference to the anterior condyles differentiated between the two study groups most clearly. LPT and LPA with reference to the anterior condyles differentiated the study groups better than LPT and LPA with reference to the posterior condyles. The reproducibility was good except for interobserver comparison of CA and SA. The use of an imaging plane selected at the midpoint of the patellar articular cartilage increases the sensitivity of the measurements, since it takes into account both the height of the patella and the tendency towards lateralization. These results indicate that patellar tilt is best measured with the LPA index and patellar lateralization with the L/PW index at 0 knee flexion. This study should always include isometric contraction of the quadriceps muscle. (orig.)

Magnetic resonance imaging of patellofemoral relationships

International Nuclear Information System (INIS)

Koskinen, S.K.; Taimela, S.; Nelimarkka, O.; Komu, M.; Kujala, U.M.

1993-01-01

Patellofemoral relationships were analyzed in 11 patients (13 knees) with patellar dislocation and 15 asymptomatic subjects (15 knees) at 0 and 20 of flexion. The measurements were made from five consecutive axial images through the patellofemoral joint. The six indices measured were lateral patellar tilt (LPT), lateral patellofemoral angle (LPA), lateral patellar displacement (LPD), patella-lateral condyle index (L/PW), congruence angle (CA), and sulcus angle (SA). The reproducibility of the method was evaluated. The difference between the two study groups was more evident at 0 than at 20 of knee flexion. Significant differences were noted between measurements made at different levels of the joint, particularly in the controls. Isometric contraction of the quadriceps muscle lateralized and tilted the patella slightly in both groups. L/PW with and without quadriceps muscle contraction, and LPA with reference to the anterior condyles differentiated between the two study groups most clearly. LPT and LPA with reference to the anterior condyles differentiated the study groups better than LPT and LPA with reference to the posterior condyles. The reproducibility was good except for interobserver comparison of CA and SA. The use of an imaging plane selected at the midpoint of the patellar articular cartilage increases the sensitivity of the measurements, since it takes into account both the height of the patella and the tendency towards lateralization. These results indicate that patellar tilt is best measured with the LPA index and patellar lateralization with the L/PW index at 0 knee flexion. This study should always include isometric contraction of the quadriceps muscle. (orig.)

Ligamentous and capsular restraints to experimental posterior elbow joint dislocation

DEFF Research Database (Denmark)

Deutch, S.R.; Olsen, B.S.; Jensen, S.L.

2003-01-01

the anterior capsule and the lateral collateral ligament complex (LCLC), whereas in the flexed elbow the anterior capsule did not have a stabilizing effect. In flexed joint positions, the LCLC seems to be the only immediate stabilizer against PEFR, and thereby against posterolateral instability and possibly...... against posterior dislocation. The medial collateral ligament did not have any immediate stabilizing effect, but it prevented the final step of the posterior dislocation....

Anterior Hip Dislocation in a Football Player: A Case Report

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Alexander Schuh

2009-01-01

Full Text Available Hip dislocations during sporting activities represent only 2%–5% of all hip dislocations. Most hip dislocations in sports can be categorised as “less complicated traumatic hip dislocations” by the Stewart-Milford classification due to the fact that minimal force is involved. The incidence of avascular necrosis of the femoral head greatly increases if the time to reduction is more than six hours. We report the case of a 38-year-old football player who suffered hip dislocation while kicking the ball with the medial aspect of the right foot in an external rotated manner of the right hip. Closed reduction was performed within 2 hours; postoperative follow-up was uneventful. Six months later the patient is out of any complaints; there is no sign of AVN of the femoral head.

Chronic asymptomatic dislocation of a total hip replacement: a case report

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Lidder Surjit

2009-08-01

Full Text Available Abstract Introduction Dislocation of a prosthetic hip is the second most common complication after thromboembolic disease in patients undergoing total hip arthroplasty, with an incidence reported as 0.5 to 20%. Although the period of greatest risk for dislocation has been reported to be within the first few months after surgery, late dislocation occurs more commonly then previously thought. Case presentation A 60-year-old man underwent a right Exeter cemented total hip replacement and was subsequently discharged after appropriate follow-up. He next presented 8 years later complaining of pain in the left groin. An anterioposterior radiograph of the pelvis revealed degenerative changes in the left hip and a dislocated right total hip replacement. The dislocated femoral component had formed a neoacetabulum within the ilium, in which it was freely articulating. He remained pain-free on this side, had 5 cm of true leg length shortening with a good range of movement and was very pleased with his hip replacement. He was later placed on the waiting list for a left total hip replacement. Conclusion This case illustrates that a dislocated total hip replacement may occasionally not cause symptoms that cause significant discomfort or reduction in range of movement. The prosthetic femoral head can form a neoacetabulum allowing a full range of pain-free movement. Furthermore it emphasises that with an increased trend to earlier hospital discharge and shorter follow-up, potential complications may be missed. We urge a low index of suspicion for potential complications and suggest that regular review with radiographic follow-up should be made.

Magnetic resonance imaging in the evaluation of osteochondritis dissecans of the patella

International Nuclear Information System (INIS)

Choi, Yun Sun; Cohen, Noah A.; Potter, Hollis G.; Mintz, Douglas N.

2007-01-01

The objective was to evaluate the magnetic resonance (MR) appearance of patellar osteochondritis dissecans (OCD). We retrospectively analyzed MR images of 16 patients (18 cases, mean age 20 years) using OCD of the patella. In 5 cases surgery was carried out, and we compared the surgical findings with the MR imaging findings in these cases. In all 18 cases, OCD was located central-inferiorly on the patella, and the average size was 11 x 11 x 7 mm. Subchondral deformities were present in 16 out of 18 cases (88.9%), subchondral cyst formation in 4 cases (22.2%), reactive bone marrow signal in 8 cases (44.4%), overlying patellar cartilage abnormality in 14 cases (77.8%), loose body in 2 cases (11.1%), patella alta in 8 cases (44.4%), hypoplastic sulcus in 7 cases (38.9%), and synovitis in 4 cases (22.2%). In all 5 cases in which surgery was carried out, the cartilage abnormality classified on the MR images was confirmed, and a loose body was removed at arthroscopy in 2 of the 5 cases. Magnetic resonance imaging of patellar OCD typically shows subchondral deformity and variable abnormalities of the overlying patellar cartilage located central-inferiorly on the patella. (orig.)

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

LENUS (Irish Health Repository)

Thomason, Katherine

2014-07-01

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

Posterior defects of the patella on CT arthrograms. Demonstration and differential diagnosis

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Lehner, K.; Reiser, M.; Hawe, W.; Smasal, V.

1986-01-01

Changes of the posterior bony and cartilaginous surfaces of the patella as seen on CT arthrograms are described in the case of bipartite patellae, fractures and ossification defects. Contrary to present opinion, cartilaginous lesions are frequently seen on CT arthrograms. This is also true for discreet and partial ossification defects which are not visible on conventional X-rays and are described here for the first time. The aetiology, morphogenesis and clinical examples are discussed.

Brown tumor of the patella caused by primary hyperparathyroidism: A case report

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Irie, Tomoko; Mawatari, Taro; Ikemura, Satoshi; Matsui, Gen; Iguchi, Takahiro; Mitsuyasu, Hiroaki [Orthopaedic Surgery, Hamanomachi Hospital, Fukuoka (Japan)

2015-06-15

It has been reported that the common sites of brown tumors are the jaw, pelvis, ribs, femurs and clavicles. We report our experience in a case of brown tumor of the patella caused by primary hyperparathyroidism. An initial radiograph and CT showed an osteolytic lesion and MR images showed a mixed solid and multiloculated cystic tumor in the right patella. One month after the parathyroidectomy, rapid bone formation was observed on both radiographs and CT images.1.

A Case of Patella Metastasis of Papillary Thyroid Carcinoma

International Nuclear Information System (INIS)

Han, Eun Ji; Choi, Woo Hee; Chung, Yong An; Sohn, Hyung Sun; Kang, Chang Suk

2009-01-01

A 73-year-old man presented with a chief complaint of progressive left knee pain for two months. He had a history of total thyroidectomy and central lymph node dissection due to papillary thyroid carcinoma three months ago. MRI images revealed a solid mass in the left patella. A solid mass demonstrated low signal on T1 weighed image, and high signal on T2 weighed image. And whole body bone scan showed focal photon defect in same lesion of left patella. The histologic result of left knee lesion was adenocarcinoma, consistent with metastatic papillary thyroid carcinoma. Although patellar metastasis of papillary thyroid carcinoma is very rare, when knee pain and radiologic abnormality are noted, differential diagnosis of metastasis is necessary

THE ECOLOGY OF PATELLA LINNAEUS FROM THE CAPE ...

African Journals Online (AJOL)

all species of Patella,. and its colour varies according to the colour of the limpet. ...... A comparable situation exists on the Pacific coast of North America, where .... freshwater and positively to sea water, so that rainwater pools will be avoided. R.

A STUDY ON THE MANAGEMENT OF DISPLACED FRACTURES OF PATELLA USING MODIFIED TENSION BAND WIRING

Directory of Open Access Journals (Sweden)

Hari Babu

2015-10-01

Full Text Available INTRODUCTION: Patella is an important component of the extensor mechanism of the knee. A patella fracture constitutes 1% of all skeletal fractures resulting from either direct or indirect trauma. Any improper and inadequate treatment would inevitably lead to a disability which would be most perceptibly felt in a country like India, where squatting is important activity in daily life. The goal of treatment is to regain the continuity of the extensor mechanism and congruity of patellofemoral a rticulation so that the normal function of the knee can be restored. Several techniques have been described for internal fixation of fractures of patella. The ideal fixation for the fracture patella is that it should be strong enough to allow early mobiliz ation, reduce posttraumatic stiffness and perhaps help the healing of the articular surface . AIMS: To analyze the functional outcome of displaced transverse fractures of the patella treated by Modified Tension Band Wiring principle (Muller using A. Dutta & S. K. Gupta Scoring System. To extend the application of Modified Tension Band wiring for minimally comminuted fractures of patella and assesses the results. CONCLUSION : The present study shows that modified tension band wiring (Muller is an effective p rocedure in the management of displaced transverse patellar fractures, with excellent to good results. Minimally comminuted patellar fractures also yielded excellent to good results with Modified tension band wiring as an extended application. The results in the present study are comparable to other modifications of Tension Band Wiring principle. The surgery of Modified Tension Band Wiring gives rigid fixation and helps in early mobilization. Regular and scheduled post- operative physiotherapy plays an impor tant role in the functional outcome.

Epidemiology, Etiology, and Prevention of Late IOL-Capsular Bag Complex Dislocation: Review of the Literature

OpenAIRE

Ascaso, Francisco J.; Huerva, Valent?n; Grzybowski, Andrzej

2015-01-01

Posterior chamber intraocular lens (PC-IOL) subluxation is uncommon but represents one of the most serious complications following phacoemulsification. Late spontaneous IOL-capsular bag complex dislocation is defined as occurring three months or later following cataract surgery. Unlike early IOL dislocation, late spontaneous IOL dislocation is due to a progressive zonular dehiscence and contraction of the capsular bag many years what seemed to be uneventful surgery. In recent years, late in-t...

[Chondromalacia patellae--arthrographic observations on the genesis and diagnosis of cartilaginous damage (author's transl)].

Science.gov (United States)

Rau, W S; Hehne, H J; Schlageter, M

1979-06-01

Thanks to recent advances in arthrography, diagnosis of cartilaginous lesions has increasingly become a task of the radiologist. An accurate assessment of the cartilage of the femoropatellar joint can be established via double-contrast technique and so-called "défilé" projections, whereas the axial projection of the patella without contrast medium shows only secondary arthrotic changes of bone and is unsuitable for demonstrating early cartilaginous damage. The classification of dysplastic patellae into different types according to Wiberg and Baumgartl yields a statistical correlation with the frequency of chondromalacia, but does not give any conclusive evidence in individual cases. A special influence on joint mechanics and the development of chondromalacia patellae is exercised by a cartilaginous ridge of the medial patellar facette.

Epitaxial strain relaxation by provoking edge dislocation dipoles

Science.gov (United States)

Soufi, A.; El-Hami, K.

2018-02-01

Thin solid films have been used in various devices and engineering systems such as rapid development of highly integrated electronic circuits, the use of surface coatings to protect structural materials in high temperature environments, and thin films are integral parts of many micro-electro-mechanical systems designed to serve as sensors, actuators. Among techniques of ultra-thin films deposition, the heteroepitaxial method becomes the most useful at nanoscale level to obtain performed materials in various applications areas. On the other hand, stresses that appeared during the elaboration of thin films could rise deformations and fractures in materials. The key solution to solve this problem at the nanoscale level is the nucleation of interface dislocations from free surfaces. By provoking edge dislocation dipoles we obtained a strain relaxation in thin films. Moreover, the dynamic of nucleation in edge dislocations from free lateral surfaces was also studied.

Effect of aspirin treatment on chondromalacia patellae.

OpenAIRE

Bentley, G; Leslie, I J; Fischer, D

1981-01-01

Twenty-nine patients (21 females and 8 males) with chondromalacia patellae diagnosed by arthroscopy were randomly allocated to receive aspirin or placebo for 3 months. Clinical and arthroscopic examination after 3 months showed no significant change in symptoms, signs, or macroscopic appearances in either group. Surgical treatment was performed in 14 patients for deteriorating symptoms.

Chondromalacia of patella. Haglund-Loewen Frund disease

International Nuclear Information System (INIS)

Pereira, L.F.; Hemais, P.M.P.G.; Carmo, M.C.R. do; Martins, H.H.A.

1986-01-01

A study of 15 cases of chondromalacia of patella is presented. The investigation and diagnosis through conventional radiology pneumoartography, arthroscopy, urgical and patological anatomy studies are done. The clinical aspects, the incidence in relation to the age and sex, the x-ray characteristics and the gross features viewed at the surgery are emphasized. (Author) [pt

Dislocation climb models from atomistic scheme to dislocation dynamics

OpenAIRE

Niu, Xiaohua; Luo, Tao; Lu, Jianfeng; Xiang, Yang

2016-01-01

We develop a mesoscopic dislocation dynamics model for vacancy-assisted dislocation climb by upscalings from a stochastic model on the atomistic scale. Our models incorporate microscopic mechanisms of (i) bulk diffusion of vacancies, (ii) vacancy exchange dynamics between bulk and dislocation core, (iii) vacancy pipe diffusion along the dislocation core, and (iv) vacancy attachment-detachment kinetics at jogs leading to the motion of jogs. Our mesoscopic model consists of the vacancy bulk dif...

Influence of patellar type and localization on chondromaliacia of patella, magnetic resonanse diagnostics

OpenAIRE

Žukauskas, Tomas

2017-01-01

Tomas Žukauskas Master’s thesis – influence of patellar type and localization on chondromaliacia of patella, magnetic resonanse diagnostics. Academic supervisor Prof. Eglė Monastyreckienė. Place of study was Lithuanian University of Health Sciences, Radiology department. The aim of study: to investigate the link between patellar type and localization with chondromaliacia of the patella using magnetic resonanse imaging. The objectives were: to investigate patellar type’s influence on its ch...

Mechanism of death at high temperatures in Helix and Patella

Energy Technology Data Exchange (ETDEWEB)

Grainger, J N.R.

1975-10-01

In Patella vulgata and Helix aspersa which had been killed by exposure to high temperatures, the rates of oxygen consumption of gill, foot muscle and hepatopancreas are remarkably steady when measured at lower temperatures, although the absolute levels are in some cases different from normal animals. These tissues are thus substantially metabolically intact in heat dead individuals. In Helix there is a fall in blood sodium and a rise in blood potassium during heat death. In Patella there is a marked rise in blood Na/sup +/ and a consequent disturbance of the Na/sup +//K/sup +/ ratio. These ionic disturbances are thought to be a prime cause of heat death. The significance of the results is discussed.

Retrosternal dislocation of the clavicle in children - A case report and review of the literature

International Nuclear Information System (INIS)

Salazar Serrano, Guillermo; Monsalve, Francisco Javier

2004-01-01

The esternoclavicular dislocations are so rare that constitute 1% of all dislocations. Currently there are just about 100 cases of retrosternal dislocations reported in world literature. In spite of the low frequency of these lesions, early diagnosis is mandatory in avoid the multiple and occasionally associated disastrous complications and to provide adequate treatment. On the other hand retrosternal displacement occurs in later teenagers or young adults, being extremely rare before age 12. The case presented in this article illustrated sternoclavicular dislocations with posterior displacement in an 11-year-old boy, successfully closer reduced at an early time

Effect of aspirin treatment on chondromalacia patellae.

Science.gov (United States)

Bentley, G; Leslie, I J; Fischer, D

1981-01-01

Twenty-nine patients (21 females and 8 males) with chondromalacia patellae diagnosed by arthroscopy were randomly allocated to receive aspirin or placebo for 3 months. Clinical and arthroscopic examination after 3 months showed no significant change in symptoms, signs, or macroscopic appearances in either group. Surgical treatment was performed in 14 patients for deteriorating symptoms. Images PMID:7008711

Interaction of 〈1 0 0〉 dislocation loops with dislocations studied by dislocation dynamics in α-iron

Energy Technology Data Exchange (ETDEWEB)

Shi, X.J.; Dupuy, L. [CEA, DEN, SRMA, F-91191 Gif-sur-Yvette (France); Devincre, B. [Laboratoire d’Etude des Microstructures, CNRS-ONERA, 29 av. de la Division Leclerc, 92322 Châtillon Cedex (France); Terentyev, D. [SCK–CEN, Nuclear Materials Science Institute, Boeretang 200, B-2400 Mol (Belgium); Vincent, L. [CEA, DEN, SRMA, F-91191 Gif-sur-Yvette (France)

2015-05-15

Highlights: • Interactions between edge dislocations and radiation-induced loops were studied by dislocation dynamics. • Dislocation dynamics results are directly compared to molecular dynamics results. • The complex elementary reactions are successfully reproduced. • The critical shear stress to overcome individual loops if reproduced quantitatively. - Abstract: Interstitial dislocation loops with Burgers vector of 〈1 0 0〉 type are formed in α-iron under neutron or heavy ion irradiation. As the density and size of these loops increase with radiation dose and temperature, these defects are thought to play a key role in hardening and subsequent embrittlement of iron-based steels. The aim of the present work is to study the pinning strength of the loops on mobile dislocations. Prior to run massive Dislocation Dynamics (DD) simulations involving experimentally representative array of radiation defects and dislocations, the DD code and its parameterization are validated by comparing the individual loop–dislocation reactions with those obtained from direct atomistic Molecular Dynamics (MD) simulations. Several loop–dislocation reaction mechanisms are successfully reproduced as well as the values of the unpinning stress to detach mobile dislocations from the defects.

Unusual inferior dislocation of shoulder: reduction by two-step maneuver: a case report

Directory of Open Access Journals (Sweden)

Patro Dilip K

2009-11-01

Full Text Available Abstract Dislocation of the shoulder is the commonest of all large joint dislocations. Inferior dislocation constitutes 0.5% of all shoulder dislocations. It characteristically presents with overhead abduction of the arm, the humerus being parallel to the spine of scapula. We present an unusual case of recurrent luxatio erecta in which the arm transformed later into an adducted position resembling the more common anterior shoulder dislocation. Such a case has not been described before in English literature. Closed reduction by the two-step maneuver was successful with a single attempt. MRI revealed posterior labral tear and a Hill-Sachs variant lesion on the superolateral aspect of humeral head. Immobilisation in a chest-arm bandage followed by physiotherapy yielded excellent results. The case is first of its kind; the unusual mechanism, unique radiological findings and alternate method of treatment are discussed.

Primary ankle arthrodesis for neglected open Weber B ankle fracture dislocation.

Science.gov (United States)

Thomason, Katherine; Ramesh, Ashwanth; McGoldrick, Niall; Cove, Richard; Walsh, James C; Stephens, Michael M

2014-01-01

Primary ankle arthrodesis used to treat a neglected open ankle fracture dislocation is a unique decision. A 63-year-old man presented to the emergency department with a 5-day-old open fracture dislocation of his right ankle. After thorough soft tissue debridement, primary arthrodesis of the tibiotalar joint was performed using initial Kirschner wire fixation and an external fixator. Definitive soft tissue coverage was later achieved using a latissimus dorsi free flap. The fusion was consolidated to salvage the limb from amputation. The use of primary arthrodesis to treat a compound ankle fracture dislocation has not been previously described. Copyright © 2014 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Does different duration of non-operative immobilization have an effect on the redislocation rate of primary patellar dislocation?

DEFF Research Database (Denmark)

Kaewkongnok, Bo; Bøvling, Anders; Milandt, Nikolaj

2018-01-01

BACKGROUND: Immobilization devices such as plaster splints, casts and braces have been used for first time patellar dislocation (FTPD) in order to prevent redislocation. This study evaluates different non-operative immobilization regimes upon rates of redislocation. METHODS: A retrospective cohort...... study with a study population of 1366 in which 601 subjects under 30years with FTPD were included from three hospitals. Exclusion criteria were osteochondral fracture, ligament injury and subluxation. Subjects were divided into five groups; unknown/none, two weeks of brace, two weeks of brace followed...... by bandage, four weeks of brace and six weeks of brace with increasing of range of motion. Radiographs were evaluated for trochlear dysplasia (TD), patella alta, trochlear depth and growth zone. Crude analysis and logistic regression adjusted for radiographic assessments, age, gender and rehabilitation...

Imaging tumors of the patella

Energy Technology Data Exchange (ETDEWEB)

Casadei, R., E-mail: roberto.casadei@ior.it [Department of Orthopaedic Oncology, Istituto Ortopedico Rizzoli, Bologna (Italy); Kreshak, J., E-mail: j.kreshak@yahoo.com [Department of Orthopaedic Oncology, Istituto Ortopedico Rizzoli, Bologna (Italy); Department of Pathology, Istituto Ortopedico Rizzoli, Bologna (Italy); Rinaldi, R. [Department of Radiology, Istituto Ortopedico Rizzoli, Bologna (Italy); Rimondi, E., E-mail: eugenio.rimondi@ior.it [Department of Radiology, Istituto Ortopedico Rizzoli, Bologna (Italy); Bianchi, G., E-mail: giuseppe.bianchi@ior.it [Department of Orthopaedic Oncology, Istituto Ortopedico Rizzoli, Bologna (Italy); Alberghini, M., E-mail: marco.alberghini@ior.it [Department of Pathology, Istituto Ortopedico Rizzoli, Bologna (Italy); Ruggieri, P. [Department of Orthopaedic Oncology, Istituto Ortopedico Rizzoli, Bologna (Italy); Vanel, D., E-mail: daniel.vanel@ior.it [Department of Radiology, Istituto Ortopedico Rizzoli, Bologna (Italy); Department of Pathology, Istituto Ortopedico Rizzoli, Bologna (Italy)

2013-12-01

Background: Patellar tumors are rare; only a few series have been described in the literature and radiographic diagnosis can be challenging. We reviewed all patellar tumors at one institution and reviewed the literature. Materials and methods: In an evaluation of the database at one institution from 1916 to 2009, 23,000 bone tumors were found. Of these, 41 involved the patella. All had imaging studies and microscopic diagnostic confirmation. All medical records, imaging studies, and pathology were reviewed. Results: There were 15 females and 26 males, ranging from 8 to 68 years old (average 30). There were 30 benign tumors; eight giant cell tumors, eight chondroblastomas, seven osteoid osteomas, two aneurysmal bone cysts, two ganglions, one each of chondroma, exostosis, and hemangioma. There were 11 malignant tumors: five hemangioendotheliomas, three metastases, one lymphoma, one plasmacytoma, and one angiosarcoma. Conclusion: Patellar tumors are rare and usually benign. As the patella is an apophysis, the most frequent lesions are giant cell tumor in the adult and chondroblastoma in children. Osteoid osteomas were frequent in our series and easily diagnosed. Metastases are the most frequent malignant diagnoses in the literature; in our series malignant vascular tumors were more common. These lesions are often easily analyzed on radiographs. CT and MR define better the cortex, soft tissue extension, and fluid levels. This study presents the imaging patterns of the more common patellar tumors in order to help the radiologist when confronted with a lesion in this location.

Isolated patellofemoral arthroplasty reproduces natural patellofemoral joint kinematics when the patella is resurfaced.

Science.gov (United States)

Vandenneucker, Hilde; Labey, Luc; Vander Sloten, Jos; Desloovere, Kaat; Bellemans, Johan

2016-11-01

The objectives of this in vitro project were to compare the dynamic three-dimensional patellofemoral kinematics, contact forces, contact areas and contact pressures of a contemporary patellofemoral prosthetic implant with those of the native knee and to measure the influence of patellar resurfacing and patellar thickness. The hypothesis was that these designs are capable to reproduce the natural kinematics but result in higher contact pressures. Six fresh-frozen specimens were tested on a custom-made mechanical knee rig before and after prosthetic trochlear resurfacing, without and with patellar resurfacing in three different patellar thicknesses. Full three-dimensional kinematics were analysed during three different motor tasks, using infrared motion capture cameras and retroflective markers. Patellar contact characteristics were registered using a pressure measuring device. The patellofemoral kinematic behaviour of the patellofemoral arthroplasty was similar to that of the normal knee when the patella was resurfaced, showing only significant (p patellofemoral kinematics acceptable well when the patella was resurfaced. From a kinematic point of view, patellar resurfacing may be advisable. However, the substantially elevated patellar contact pressures remain a point of concern in the decision whether or not to resurface the patella. This study therefore not only adds a new point in the discussion whether or not to resurface the patella, but also supports the claimed advantage that a patellofemoral arthroplasty is capable to reproduce the natural knee kinematics.

Patella tendon injuries secondary to cement spacers used at first-stage revision of infected total knee replacement

Directory of Open Access Journals (Sweden)

Wasim S Khan

2015-04-01

Full Text Available We describe a series of three patients who sustained patella tendon injuries in infected TKAs following the use of a static cement spacer at first-stage knee revision. The patella tendon injuries resulted in significant compromise to wound healing and knee stability requiring multiple surgeries. The mid-term function was poor with an Oxford score at 24 months ranging from 12-20. Based on our experience, we advise caution in the use of static cement spacer blocks. If they are to be used, we recommend that they should be keyed in the bone to prevent patella tendon injuries.

Can turned inward patella predict an excess of femoral anteversion during gait in spastic diplegic children?

Science.gov (United States)

Simon, Anne-Laure; Presedo, Ana; Ilharreborde, Brice; Mallet, Cindy; Mazda, Keyvan; Penneçot, Georges-François

2014-06-01

Determining patellar orientation in the transverse plane during observational gait analysis is a fundamental aspect of physical examinations. Many physicians consider that an abnormal position of the patella in the transverse planes is only explained by a rotational abnormality of the proximal femur. A total of 188 spastic diplegic children with cerebral palsy were reviewed (376 lower limbs). The physical examination included observation of patellar orientation at midstride and measuring femoral anteversion (FA). All patients also underwent 3-dimensional (3D) computerized gait analysis of pelvic and hip rotation kinematics. Observational gait analysis and videotapes found 103 children (206 lower limbs) with inturned patella at midstance. Kinematic data from 3D gait analysis showed that the visual impression of turned inward patella was erroneous in 48 limbs. Of the remaining 158 lower limbs, 117 (74%) exhibited excessive FA and 41 (26%) did not. Of the 117 with excessive FA, kinematics showed only 66 (56%) with excessive internal hip rotation (with or without excessive internal pelvic rotation). Of the 41 lower limbs without excessive FA, 25 were explained by excessive internal pelvic rotation and 16 were explained by excessive internal hip rotation (isolated spasticity and/or contracture of internal rotator muscles). Turned inward patella was caused by isolated excessive internal pelvic rotation in 48%, excessive internal hip rotation in 35% (including 44 cases with excessive FA and 12 cases with isolated spasticity and/or contracture of internal hip rotators), and excessive internal hip rotation combined with excessive internal pelvic rotation in 17%. Excessive FA was not the only cause of turned inward patella gait and could not explain this gait anomaly by itself. Excessive internal pelvic rotation was the most frequent cause of turned inward patella gait. Level IV.

[Preliminary investigation on the pathogeny, diagnosis and treatment of chondromalacia patella].

Science.gov (United States)

Ye, Q B; Wu, Z H; Wang, Y P; Lin, J; Qiu, G X

2001-04-01

This paper presents the preliminary investigation on chondromalacia patella at our department in recent years. A random cluster sampling survey covering 2743 normal persons was carried out. The prevalence rate is 36.2%. It was found that, applying transmission electron microscope and immunohistochemical methods on to cartilage tissues of the abnormal region, articular cartilage necrosis was in direct proportion with the abnormal pressure, while the restoration capability of local chondrocytes was in inverse proportion with pathological changes and the pressure. The chondromalacia patella was produced by repeated abnormal stress acting on the cartilage. The stress derived from the uncongruency and the decreasing in the contact area of patellofemoral joint when the subluxation or tilt of patellae was caused by the abnormal anatomical and biomechanical relationship. The initial lesion was at the matrix of cartilage, the collagen network was disrupted, then proteoglycan was lost. The microenvironment of chondrocytes was changed with degradation of matrix. So the chondrocytes became degenerative and necrosis from superficial to deep layer, then feed back the matrix again. Finally, the total cartilage layer might disappear, and the bone under cartilage might proliferate. At late stage, the cartilage was completely destroyed and had no self-restorative ability. Therefore, early diagnosis and treatment are necessary. It is highly suggested axis radiograph of the knee with the tibiae tuberositas localization are helpful to early diagnosis. Furthermore, JKY-Muscle Rehabilitation Instrument is invented for non-operative therapy. It enhances muscle power by selective training of the vastus medialis muscle using electrical stimulator to relieve pain and correct subluxation of patella with 90% efficiency (63% of excellent-effective rate). In late stage, patellofemoral replacement is recommended. The excellent-effective rate is 86.3%.

The diagnostic value of the Clarke sign in assessing chondromalacia patella.

Science.gov (United States)

Doberstein, Scott T; Romeyn, Richard L; Reineke, David M

2008-01-01

Various techniques have been described for assessing conditions that cause pain at the patellofemoral (PF) joint. The Clarke sign is one such test, but the diagnostic value of this test in assessing chondromalacia patella is unknown. To (1) investigate the diagnostic value of the Clarke sign in assessing the presence of chondromalacia patella using arthroscopic examination of the PF joint as the "gold standard," and (2) provide a historical perspective of the Clarke sign as a clinical diagnostic test. Validation study. All patients of one of the investigators who had knee pain or injuries unrelated to the patellofemoral joint and were scheduled for arthroscopic surgery were recruited for this study. A total of 106 otherwise healthy individuals with no history of patellofemoral pain or dysfunction volunteered. The Clarke sign was performed on the surgical knee by a single investigator in the clinic before surgery. A positive test was indicated by the presence of pain sufficient to prevent the patient from maintaining a quadriceps muscle contraction against manual resistance for longer than 2 seconds. The preoperative result was compared with visual evidence of chondromalacia patella during arthroscopy. Sensitivity was 0.39, specificity was 0.67, likelihood ratio for a positive test was 1.18, likelihood ratio for a negative test was 0.91, positive predictive value was 0.25, and negative predictive value was 0.80. Diagnostic validity values for the use of the Clarke sign in assessing chondromalacia patella were unsatisfactory, supporting suggestions that it has poor diagnostic value as a clinical examination technique. Additionally, an extensive search of the available literature for the Clarke sign reveals multiple problems with the test, causing significant confusion for clinicians. Therefore, the use of the Clarke sign as a routine part of a knee examination is not beneficial, and its use should be discontinued.

Tuberculosis of the patella masquerading as prepatellar bursitis

Science.gov (United States)

Kulkarni, S

2013-01-01

Tuberculosis of bone is an uncommon entity in the Western world. We present a case of tuberculosis of the patella mimicking prepatellar bursitis in an otherwise fit and well woman of Bangladeshi origin. We believe tuberculosis of bone should form a differential diagnosis of the swollen knee in high risk patients. PMID:23317718

[Elbow dislocation].

Science.gov (United States)

de Pablo Márquez, B; Castillón Bernal, P; Bernaus Johnson, M C; Ibañez Aparicio, N M

Elbow dislocation is the most frequent dislocation in the upper limb after shoulder dislocation. Closed reduction is feasible in outpatient care when there is no associated fracture. A review is presented of the different reduction procedures. Copyright © 2017 Sociedad Española de Médicos de Atención Primaria (SEMERGEN). Publicado por Elsevier España, S.L.U. All rights reserved.

The role of autologous chondrocyte implantation in the treatment of symptomatic chondromalacia patellae.

Science.gov (United States)

Macmull, Simon; Jaiswal, Parag K; Bentley, George; Skinner, John A; Carrington, Richard W J; Briggs, Tim W R

2012-07-01

Chondromalacia patella is a distinct clinical entity of abnormal softening of the articular cartilage of the patella, which results in chronic retropatellar pain. Its aetiology is still unclear but the process is thought to be a due to trauma to superficial chondrocytes resulting in a proteolytic enzymic breakdown of the matrix. Our aim was to assess the effectiveness of autologous chondrocyte implantation on patients with a proven symptomatic retropatellar lesion who had at least one failed conventional marrow-stimulating therapy. We performed chondrocyte implantation on 48 patients: 25 received autologous chondrocyte implantation with a type I/III membrane (ACI-C) method (Geistlich Biomaterials, Wolhusen, Switzerland), and 23 received the Matrix-assisted Chondrocyte Implantation (MACI) technique (Genzyme, Kastrup, Denmark). Over a mean follow-up period of 40.3 months, there was a statistically significant improvement in subjective pain scoring using the visual analogue scale (VAS) and objective functional scores using the Modified Cincinnati Rating System (MCS) in both groups. Chondromalacia patellae lesions responded well to chondrocyte implantation. Better results occurred with MACI than with ACI-C. Excellent and good results were achieved in 40% of ACI-C patients and 57% of MACI patients, but success of chondrocyte implantation was greater with medial/odd-facet lesions. Given that the MACI procedure is technically easier and less time consuming, we consider it to be useful for treating patients with symptomatic chondral defects secondary to chondromalacia patellae.

Correlation between subcutaneous knee fat thickness and chondromalacia patellae on magnetic resonance imaging of the knee.

LENUS (Irish Health Repository)

Kok, Hong Kuan

2013-08-01

Chondromalacia patellae is a common cause of anterior knee pain in young patients and can be detected noninvasively with magnetic resonance imaging (MRI). The purpose of our study was to evaluate the correlation between subcutaneous fat thickness around the knee joint on axial MRIs as a surrogate marker of obesity, with the presence or absence of chondromalacia patellae.

Microstructure of laterally overgrown GaN layers

International Nuclear Information System (INIS)

Liliental-Weber, Z.; Cherns, David

2001-01-01

Transmission electron microscopy study of plan-view and cross-section samples of epitaxial laterally overgrown (ELOG) GaN samples is described. Two types of dislocation with the same type of Burgers vector but different line direction have been observed. It is shown that threading edge dislocations bend to form dislocation segments in the c plane as a result of shear stresses developed in the wing material along the stripe direction. It is shown that migration of these dislocations involves both glide and climb. Propagation of threading parts over the wing area is an indication of high density of point defects present in the wing areas on the ELOG samples. This finding might shed light on the optical properties of such samples. [copyright] 2001 American Institute of Physics

Subtalar dislocation

International Nuclear Information System (INIS)

El-Khoury, G.Y.; Yousefzadeh, D.K.; Mulligan, G.M.; Moore, T.E.

1982-01-01

Over a period of three years we have seen nine patients with subtalar dislocation, all of whom sustained violent trauma to the region of the ankle and hind foot. All but one patient were males. Clinically a subtalar dislocation resembles a complicated fracture dislocation of the ankle but a definitive diagnosis can only be made radiographically. The mechanism of injury and radiographic features of this injury are discussed. (orig.)

(Gmelin, 1791) and Patella concolor Krauss, 1848 (Gastropoda

African Journals Online (AJOL)

1986-11-21

Nov 21, 1986 ... Trans Roy. Soc. S. Afr. 41: 111-160. BRANCH, G.M. 1975. Notes on the ecology of Patella concolor and Cellana capensis and the effects of human consumption on limpet populations. 2001 Afr. 10: 75-85. BRANCH, G.M. 1981. The biology of limpets: physical factors, energy flow, and ecological interactions.

THE ECOLOGY OF PATELLA LINNAEUS FROM THE CAPE ...

African Journals Online (AJOL)

The genus Patella comprises intertidal and infratidal animals, which- are important not only because of their relative abundance on most shores, but because of the marked effect they may have on the ecology of these shores. Despite this, little is known about their detailed ecology in South Africa. The present paper is an ...

Estimation of dislocations density and distribution of dislocations during ECAP-Conform process

Science.gov (United States)

Derakhshan, Jaber Fakhimi; Parsa, Mohammad Habibi; Ayati, Vahid; Jafarian, Hamidreza

2018-01-01

Dislocation density of coarse grain aluminum AA1100 alloy (140 µm) that was severely deformed by Equal Channel Angular Pressing-Conform (ECAP-Conform) are studied at various stages of the process by electron backscattering diffraction (EBSD) method. The geometrically necessary dislocations (GNDs) density and statistically stored dislocations (SSDs) densities were estimate. Then the total dislocations densities are calculated and the dislocation distributions are presented as the contour maps. Estimated average dislocations density for annealed of about 2×1012 m-2 increases to 4×1013 m-2 at the middle of the groove (135° from the entrance), and they reach to 6.4×1013 m-2 at the end of groove just before ECAP region. Calculated average dislocations density for one pass severely deformed Al sample reached to 6.2×1014 m-2. At micrometer scale the behavior of metals especially mechanical properties largely depend on the dislocation density and dislocation distribution. So, yield stresses at different conditions were estimated based on the calculated dislocation densities. Then estimated yield stresses were compared with experimental results and good agreements were found. Although grain size of material did not clearly change, yield stress shown intensive increase due to the development of cell structure. A considerable increase in dislocations density in this process is a good justification for forming subgrains and cell structures during process which it can be reason of increasing in yield stress.

An isolated dorso-medial dislocation of navicular bone: A case report.

Science.gov (United States)

Singh, Varun Kumar; Kashyap, Abhishek; Vargaonkar, Gauresh; Kumar, Ramesh

2015-03-01

An isolated dislocation of tarsal navicular is extremely rare injury. Usually it is associated with fracture of navicular itself or other tarsal bones of foot along with disruption of medial or lateral column of foot. Mechanism of injury is complex but usually a severe abduction force is required to produce such injury in a planter flexed foot. A 30 year old male presented with isolated navicular dislocation. Management required open reduction and fixation with k-wires. These injuries have specific complications including avascular necrosis of navicular and post-traumatic arthritis.

Effect of a patella support brace on myoelectric activity of knee joint muscles during single leg landing

Directory of Open Access Journals (Sweden)

Fatemeh Salariesker

2013-06-01

Full Text Available Introduction: Patellfemoral pain syndrome is one of the most common knee joint problems that affect athletes and non-athletes. Knee brace is often used as a treatment method for patellar realignment. The aim of the present study was to determine the effects of a patella support brace on myoelectric activity of selected knee muscles during single leg landing in healthy females. Materials and Methods: 19 healthy female students (Mean age: 23.6±1.98 years, height: 163.5±5.88 cm, weight: 62.3±3.6 kg participated in this study. Myoelectric activity of biceps femoris, semitendinosus, vastus medialis and vastus lateralis were collected during single leg landing in with and without using the patella support brace conditions.Results: Use of the patella support brace had no significant effect on myoelectric activity for the semitendinosus (p=0.668, vastus medialis (VM (p=0.915 and vastus lateralis (VL (P=0.134, while myoelectric activity for biceps femoris (p=0.005 and ratio of VM/VL myoelectric activity significantly increased (p=0.045. Conclusion: Our results revealed that biceps femoris activity and vastus medialis/vastus lateralis ratio increased after using patella support brace during single leg landing. Further studies on kinematic and kinetic variables are needed to describe these changes in muscular activity when using the patella support brace.

Dislocation-dynamics method

International Nuclear Information System (INIS)

Van Brutzel, L.

2015-01-01

Dislocation-Dynamics (DD) technique is identified as the method able to model the evolution of material plastic properties as a function of the microstructural transformation predicted at the atomic scale. Indeed, it is the only simulation method capable of taking into account the collective behaviour of a large number of dislocations inside a realistic microstructure. DD simulations are based on the elastic dislocation theory following rules inherent to the dislocation core structure often call 'local rules'. All the data necessary to establish the local rules for DD have to come directly from experiment or alternatively from simulations carried out at the atomic scale such as molecular dynamics or ab initio calculations. However, no precise information on the interaction between two dislocations or between dislocations and defects induced by irradiation are available for nuclear fuels. Therefore, in this article the DD technique will be presented and some examples are given of what can be achieved with it. (author)

Patellar Shape-Memory Fixator for the Treatment of Comminuted Fractures of the Inferior Pole of the Patella

Science.gov (United States)

Liu, Xin-Wei; Shang, Hui-Juan; Xu, Shuo-Gui; Wang, Zhi-Wei; Zhang, Chun-Cai; Fu, Qing-Ge

2011-07-01

Comminuted and displaced fractures of the inferior pole of the patella are not easy to reduce and it is difficult to fix the fragments soundly enough to allow early movement of the knee. The purpose of this study is to evaluate the clinical effectiveness of the internal fixation technique with Patellar Shape-Memory Fixator (PSMF) in acute comminuted fractures of the inferior pole of the patella. We retrospectively studied 25 patients with comminuted fractures of the inferior pole of the patella who were treated with PSMF and followed up for a mean period of 26 months (14 to 60). All the fractures healed at a mean of 6 weeks (5 to 7). The mean grading at the final follow-up was 29.5 points (27 to 30) using the Bostman score, with no observable restriction of movement. No breakage of the PSMF or infection occurred. No delayed union, nonunion, and infection were seen. This technique preserved the length of the patella, reduced the comminuted fragments of the inferior pole and avoided long-term immobilization of the knee.

Dislocation of the fibular head in an unusual sports injury: a case report

Directory of Open Access Journals (Sweden)

Ahmad Riaz

2008-05-01

Full Text Available Abstract Introduction One of the primary functions of the proximal tibiofibular joint is slight rotation to accommodate rotational stress at the ankle. Proximal tibiofibular joint dislocation is a rare injury and accounts for less than 1% of all knee injuries. This dislocation has been reported in patients who had been engaged in football, ballet dancing, equestrian jumping, parachuting and snowboarding. Case presentation A 20-year-old man was injured whilst playing football. He felt a pop in the right knee and was subsequently unable to bear weight on it. The range of movement in his knee joint was limited. Anterior-posterior and lateral X-rays of the knee revealed anterolateral dislocation of the proximal tibiofibular joint. Comparison views confirmed the anterolateral dislocation. He had a failed manipulation under anaesthesia and the joint needed an open reduction in which the fibular head was levered back into place. Operative findings revealed a horizontal type of joint. Conclusion An exceedingly rare dislocation of a horizontal type of proximal tibiofibular joint was presented following a football injury. This dislocation was irreducible by a closed method.

Chondropathia patellae - preoperative and postoperative demonstration of the patellar structure in plain roentgenography

International Nuclear Information System (INIS)

Schumacher, K.A.; Mutschler, W.; Bargon, G.

1982-01-01

The study is based on 86 patients surgically treated for chondromalacia patellae, who in a 2 year follow-up were controlled by defile-radiographs and clinical examination. While there was an improvement of all clinical symptoms examined, no significant change in the radiologic appearance of the patellar structure was observed as compared with the pre-operative status. This includes that neither significant changes indicating development of arthrosis nor aggravation of pre-existing arthrotic lesions could be found. However, it is commonly suggested from roentgenographic findings with type 3 lesions, that severe chondromalacia patellae may be a precursor of osteoarthrosis. (orig.) [de

Chondropathia patellae - preoperative and postoperative demonstration of the patellar structure in plain roentgenography

Energy Technology Data Exchange (ETDEWEB)

Schumacher, K.A.; Mutschler, W.; Bargon, G.

1982-07-01

The study is based on 86 patients surgically treated for chondromalacia patellae, who in a 2 year follow-up were controlled by defile-radiographs and clinical examination. While there was an improvement of all clinical symptoms examined, no significant change in the radiologic appearance of the patellar structure was observed as compared with the pre-operative status. This includes that neither significant changes indicating development of arthrosis nor aggravation of pre-existing arthrotic lesions could be found. However, it is commonly suggested from roentgenographic findings with type 3 lesions, that severe chondromalacia patellae may be a precursor of osteoarthrosis.

Patella position is not a determinant for anterior knee pain 10 years after balanced gap total knee arthroplasty.

Science.gov (United States)

van Houten, Albert H; Heesterbeek, Petra J C; Wymenga, Ate B

2016-08-01

Incidence of anterior knee pain after total knee arthroplasty (TKA) is reported to be between 4 and 49 %. The incidence of AKP at long-term follow-up and possible determinants after cruciate cruciate-retaining TKA were investigated. A 10-year follow-up of a cohort of 55 patients (63 TKAs), who received the balanSys™ cruciate-retaining total knee system (Mathys Ltd, Bettlach, Switzerland) between 1999 and 2002, was performed. Patients had undergone the balanced gap technique, with either a fixed bearing or an AP-glide bearing. Standardised diagnostic questions regarding AKP were collected and categorised into two groups: those with and without AKP. The lateral patellar tilt, patellar displacement measurement and modified Insall-Salvati ratio were used for patella position evaluation on skyline radiographs. The Knee Society Score (KSS), the Knee Osteoarthritis Outcome Score (KOOS) and Numerical Rating Scales (NRS) for pain and satisfaction were obtained at follow-up. Sixteen patients in the study population experienced AKP. Incidence of AKP (fixed bearing 13/44; AP-glide bearing baring 3/17) was not dependent on type of insert (n.s.). There were no statistical differences in patella position and tibiofemoral contact point between the AKP group and the no AKP group (n.s.). KSS, KOOS, NRS-pain and NRS-satisfaction were significantly lower for the patients with AKP (all p years after balanced gap TKA. Postoperative patella positioning was not found to be a determinant for anterior knee pain after TKA. However, patellar displacement does not seem completely favourable. Moreover, type of bearing was not found a determinant for AKP at long-term follow-up. Lower quality prospective cohort study (<80 % follow-up, patients enrolled at different time points in disease), Level II.

Separate Vertical Wirings for the Extra-articular Fractures of the Distal Pole of the Patella

OpenAIRE

Kim, Young Mo; Yang, Jun Young; Kim, Kyung Cheon; Kang, Chan; Joo, Yong Bum; Lee, Woo Yong; Hwang, Jung Mo

2011-01-01

Purpose To evaluate the usefulness of separate vertical wirings for extra-articular fracture of distal pole of patella. Materials and Methods We have analyzed the clinical results of 18 cases that underwent separate vertical wirings for extra-articular fracture of distal pole of the patella from March 2005 to March 2010, by using the range of motion and Bostman score. Occurrence of complication was also evaluated. Additionally, by taking simple radiographs, the correlation between the postope...

Dislocation-induced stress in polycrystalline materials: mesoscopic simulations in the dislocation density formalism

Science.gov (United States)

Berkov, D. V.; Gorn, N. L.

2018-06-01

In this paper we present a simple and effective numerical method which allows a fast Fourier transformation-based evaluation of stress generated by dislocations with arbitrary directions and Burgers vectors if the (site-dependent) dislocation density is known. Our method allows the evaluation of the dislocation stress using a rectangular grid with shape-anisotropic discretization cells without employing higher multipole moments of the dislocation interaction coefficients. Using the proposed method, we first simulate the stress created by relatively simple non-homogeneous distributions of vertical edge and so-called ‘mixed’ dislocations in a disk-shaped sample, which is necessary to understand the dislocation behavior in more complicated systems. The main part of our research is devoted to the stress distribution in polycrystalline layers with the dislocation density rapidly varying with the distance to the layer bottom. Considering GaN as a typical example of such systems, we investigate dislocation-induced stress for edge and mixed dislocations, having random orientations of Burgers vectors among crystal grains. We show that the rapid decay of the dislocation density leads to many highly non-trivial features of the stress distributions in such layers and study in detail the dependence of these features on the average grain size. Finally we develop an analytical approach which allows us to predict the evolution of the stress variance with the grain size and compare analytical predictions with numerical results.

Tumour and tumour-like lesions of the patella - a multicentre experience

International Nuclear Information System (INIS)

Singh, J.; James, S.L.; Davies, A.M.; Kroon, H.M.; Woertler, K.; Anderson, S.E.

2009-01-01

Fifty-nine cases of lesions presenting in the patella were identified after review of the databases of four European bone tumour registries. Of the 59 cases, 46% were non neoplastic, 39% were benign and 15% were malignant. The commonest benign neoplasm was giant cell tumour (GCT) (11 cases). Younger patients were more likely to have a benign neoplasm. Lesions in patients less than 40 years of age included giant cell tumour, chondroblastoma, aneurysmal bone cyst (ABC), osteomyelitis, osteoid osteoma and solitary bone cyst. In patients older than 40 years, the following were common lesions: intra-osseous gout, metastasis and intra-osseous ganglion. Expansion of the patella with thinning of cortex was seen more commonly in GCT and brown tumour in hyperparathyroidism. There was associated soft tissue extension in gout and malignant lesions. (orig.)

Tumour and tumour-like lesions of the patella - a multicentre experience

Energy Technology Data Exchange (ETDEWEB)

Singh, J.; James, S.L.; Davies, A.M. [The Royal Orthopaedic Hospital, Department of Radiology, Birmingham (United Kingdom); Kroon, H.M. [Leiden University Medical Centre, Department of Radiology, C-2-S, P. O Box 9600, Leiden (Netherlands); Woertler, K. [Technische Universitaet Muenchen, Department of Radiology, Munich (Germany); Anderson, S.E. [Knochentumor- Referenzzentrum der Schweizerischen Gesellschaft fuer Pathologie, Basel (Switzerland)

2009-03-15

Fifty-nine cases of lesions presenting in the patella were identified after review of the databases of four European bone tumour registries. Of the 59 cases, 46% were non neoplastic, 39% were benign and 15% were malignant. The commonest benign neoplasm was giant cell tumour (GCT) (11 cases). Younger patients were more likely to have a benign neoplasm. Lesions in patients less than 40 years of age included giant cell tumour, chondroblastoma, aneurysmal bone cyst (ABC), osteomyelitis, osteoid osteoma and solitary bone cyst. In patients older than 40 years, the following were common lesions: intra-osseous gout, metastasis and intra-osseous ganglion. Expansion of the patella with thinning of cortex was seen more commonly in GCT and brown tumour in hyperparathyroidism. There was associated soft tissue extension in gout and malignant lesions. (orig.)

Dislocation reduction in heteroepitaxial Ge on Si using SiO{sub 2} lined etch pits and epitaxial lateral overgrowth

Energy Technology Data Exchange (ETDEWEB)

Leonhardt, Darin; Han, Sang M. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States)

2011-09-12

We report a technique that significantly reduces threading dislocations in Ge on Si heteroepitaxy. Germanium is first grown on Si and etched to produce pits in the surface where threading dislocations terminate. Further processing leaves a layer of SiO{sub 2} only within etch pits. Subsequent selective epitaxial Ge growth results in coalescence above the SiO{sub 2}. The SiO{sub 2} blocks the threading dislocations from propagating into the upper Ge epilayer. With annealed Ge films grown on Si, the said method reduces the defect density from 2.6 x 10{sup 8} to 1.7 x 10{sup 6} cm{sup -2}, potentially making the layer suitable for electronic and photovoltaic devices.

[Surgical treatment of inferior pole comminuted fractures of patella with new type tension band].

Science.gov (United States)

Sun, B; Zhang, Z S; Zhou, F; Tian, Y; Ji, H Q; Guo, Y; Lv, Y; Yang, Z W

2015-04-18

To study the effectiveness of inferior pole fracture of patella treating by the new tension band. From Dec. 2011 to Dec. 2013, 21 patients with inferior pole fracture of patella were treated with the new tension band which consisted of cannulated screw, titanium cable and shims. There were 21 patients[10 males, 11 females, the average age was 54 years(21 to 79)],of whom,all were "fell on knees". The average operation time was 89 min (57-197 min),the follow-up visits were done from 7-31 months (average 18 months), the bone healing time was from 8-12 weeks (average 10.5 weeks). The post operation assessment was done by Bostman score, from 20-30 (average 27),10 excellent,and 11 good. No complication occurred. The new tension band is the effective treatment for inferior pole fracture of patella. The internal fixation is reliable, it is simple to operate, and patients can take exercises as early as possible. Therefore, the new tension band has a better clinical value.

Twenty-degree-tilt radiography for evaluation of lateral humeral condylar fracture in children

International Nuclear Information System (INIS)

Imada, Hideaki; Tanaka, Ryuji; Itoh, Yohei; Kishi, Kazuhiko

2010-01-01

To investigate the efficacy of '20 -tilt anteroposterior (A-P) radiography' in the assessment of lateral condylar fractures of the distal humerus. Eighteen children with lateral humeral condylar fractures were studied. Every child underwent conventional A-P and lateral radiography, and six children underwent multi-detector computed tomography (MDCT). For the investigation of 20 -tilt radiography, ten children with lateral humeral condylar fractures had conventional and 20 -tilt A-P and lateral radiography both preoperatively and postoperatively. Fragment dislocation was measured at the lateral and medial margins of the fracture on both the conventional A-P and 20 -tilt A-P radiographs. The lateral condylar fragment was triangular and was most prominent posteriorly. The fracture line was typically tilted approximately 20 to a reference line perpendicular to the long axis of the humerus in the lateral view. The extent of dislocation at the lateral and medial margins of the fracture site by 20 -tilt A-P radiography (9.3 ± 3.6 mm and 5.6 ± 2.5 mm) was significantly wider than that measured by the conventional method (6.8 ± 4.1 mm and 2.0 ± 1.5 mm), which may influence treatment. Twenty-degree-tilt A-P radiography may more precisely demonstrate fragment dislocation than standard radiographs and may influence patient treatment. (orig.)

Canonical Quantization of Crystal Dislocation and Electron-Dislocation Scattering in an Isotropic Media

Science.gov (United States)

Li, Mingda; Cui, Wenping; Dresselhaus, M. S.; Chen, Gang; MIT Team; Boston College Team

Crystal dislocations govern the plastic mechanical properties of materials but also affect the electrical and optical properties. However, a fundamental and decent quantum-mechanical theory of dislocation remains undiscovered for decades. Here we present an exact and manageable Hamiltonian theory for both edge and screw dislocation line in an isotropic media, where the effective Hamiltonian of a single dislocation line can be written in a harmonic-oscillator-like form, with closed-form quantized 1D phonon-like excitation. Moreover a closed-form, position dependent electron-dislocation coupling strength is obtained, from which we obtained good agreement of relaxation time when comparing with classical results. This Hamiltonian provides a platform to study the effect of dislocation to materials' non-mechanical properties from a fundamental Hamiltonian level.

"Conjugate channeling" effect in dislocation core diffusion: carbon transport in dislocated BCC iron.

Science.gov (United States)

Ishii, Akio; Li, Ju; Ogata, Shigenobu

2013-01-01

Dislocation pipe diffusion seems to be a well-established phenomenon. Here we demonstrate an unexpected effect, that the migration of interstitials such as carbon in iron may be accelerated not in the dislocation line direction ξ, but in a conjugate diffusion direction. This accelerated random walk arises from a simple crystallographic channeling effect. c is a function of the Burgers vector b, but not ξ, thus a dislocation loop possesses the same everywhere. Using molecular dynamics and accelerated dynamics simulations, we further show that such dislocation-core-coupled carbon diffusion in iron has temperature-dependent activation enthalpy like a fragile glass. The 71° mixed dislocation is the only case in which we see straightforward pipe diffusion that does not depend on dislocation mobility.

Distribution of distances between dislocations in different types of dislocation substructures in deformed Cu-Al alloys

Energy Technology Data Exchange (ETDEWEB)

Trishkina, L., E-mail: trishkina.53@mail.ru; Zboykova, N.; Koneva, N., E-mail: koneva@tsuab.ru; Kozlov, E. [Tomsk State University of Architecture and Building, 2 Solyanaya St., Tomsk, 634003 (Russian Federation); Cherkasova, T. [Tomsk State University of Architecture and Building, 2 Solyanaya St., Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, 50 Lenin Ave., Tomsk, 634050 (Russian Federation)

2016-01-15

The aim of the investigation was the determination of the statistic description of dislocation distribution in each dislocation substructures component forming after different deformation degrees in the Cu-Al alloys. The dislocation structures were investigated by the transmission diffraction electron microscopy method. In the work the statistic description of distance distribution between the dislocations, dislocation barriers and dislocation tangles in the deformed Cu-Al alloys with different concentration of Al and test temperature at the grain size of 100 µm was carried out. It was established that the above parameters influence the dislocation distribution in different types of the dislocation substructures (DSS): dislocation chaos, dislocation networks without disorientation, nondisoriented and disoriented cells, in the walls and inside the cells. The distributions of the distances between dislocations in the investigated alloys for each DSS type formed at certain deformation degrees and various test temperatures were plotted.

Distribution of distances between dislocations in different types of dislocation substructures in deformed Cu-Al alloys

Science.gov (United States)

Trishkina, L.; Cherkasova, T.; Zboykova, N.; Koneva, N.; Kozlov, E.

2016-01-01

The aim of the investigation was the determination of the statistic description of dislocation distribution in each dislocation substructures component forming after different deformation degrees in the Cu-Al alloys. The dislocation structures were investigated by the transmission diffraction electron microscopy method. In the work the statistic description of distance distribution between the dislocations, dislocation barriers and dislocation tangles in the deformed Cu-Al alloys with different concentration of Al and test temperature at the grain size of 100 µm was carried out. It was established that the above parameters influence the dislocation distribution in different types of the dislocation substructures (DSS): dislocation chaos, dislocation networks without disorientation, nondisoriented and disoriented cells, in the walls and inside the cells. The distributions of the distances between dislocations in the investigated alloys for each DSS type formed at certain deformation degrees and various test temperatures were plotted.

Tailoring Superconductivity with Quantum Dislocations.

Science.gov (United States)

Li, Mingda; Song, Qichen; Liu, Te-Huan; Meroueh, Laureen; Mahan, Gerald D; Dresselhaus, Mildred S; Chen, Gang

2017-08-09

Despite the established knowledge that crystal dislocations can affect a material's superconducting properties, the exact mechanism of the electron-dislocation interaction in a dislocated superconductor has long been missing. Being a type of defect, dislocations are expected to decrease a material's superconducting transition temperature (T c ) by breaking the coherence. Yet experimentally, even in isotropic type I superconductors, dislocations can either decrease, increase, or have little influence on T c . These experimental findings have yet to be understood. Although the anisotropic pairing in dirty superconductors has explained impurity-induced T c reduction, no quantitative agreement has been reached in the case a dislocation given its complexity. In this study, by generalizing the one-dimensional quantized dislocation field to three dimensions, we reveal that there are indeed two distinct types of electron-dislocation interactions. Besides the usual electron-dislocation potential scattering, there is another interaction driving an effective attraction between electrons that is caused by dislons, which are quantized modes of a dislocation. The role of dislocations to superconductivity is thus clarified as the competition between the classical and quantum effects, showing excellent agreement with existing experimental data. In particular, the existence of both classical and quantum effects provides a plausible explanation for the illusive origin of dislocation-induced superconductivity in semiconducting PbS/PbTe superlattice nanostructures. A quantitative criterion has been derived, in which a dislocated superconductor with low elastic moduli and small electron effective mass and in a confined environment is inclined to enhance T c . This provides a new pathway for engineering a material's superconducting properties by using dislocations as an additional degree of freedom.

Trochleoplasty and medial patellofemoral ligament reconstruction for recurrent patellar dislocation

Directory of Open Access Journals (Sweden)

K Raghuveer Reddy

2012-01-01

Full Text Available We report a case of recurrent patellar dislocation with high-grade trochlear dysplasia which persisted despite two previous operations. We did a Dejour′s sulcus deepening trochleoplasty, medial patellofemoral ligament reconstruction, and lateral retinacular release. Trochleoplasty and medial patellofemoral ligament reconstruction is required in patients with high grade trochlear dysplasia.

Imaging patellar complications after knee arthroplasty

International Nuclear Information System (INIS)

Melloni, Pietro; Valls, Rafael; Veintemillas, Maite

2008-01-01

The purpose of this study is to describe complications affecting the patella in patients with total or partial knee arthroplasty. We respectively analysed plain-film radiographs, as well as ultrasound images when acquired, in a consecutive series of 1272 patients. The mean interval from knee replacement to patellar complications was 5 years and 7 months (range, 5 months to 14 years). The complications described include fracture, instability, dislocation or luxation, necrosis of the patella, infection of the patella, erosion of the patella, patellar impingement on the prosthesis and patellar or quadricipital tendon tear. We discuss the pathological imaging findings in the patella and their differential diagnosis after knee arthroplasty. Patellar complications after knee arthroplasty are uncommon but often potentially serious

Imaging patellar complications after knee arthroplasty

Energy Technology Data Exchange (ETDEWEB)

Melloni, Pietro [Unitat de Imatge d' Alta Tecnologia, Centre Diagnostic, Corporacio Parc Tauli, Universitat Autonoma de Barcelona, Sabadell (Barcelona) (Spain)], E-mail: pmelloni@cspt.es; Valls, Rafael; Veintemillas, Maite [Unitat de Imatge d' Alta Tecnologia, Centre Diagnostic, Corporacio Parc Tauli, Universitat Autonoma de Barcelona, Sabadell (Barcelona) (Spain)

2008-03-15

The purpose of this study is to describe complications affecting the patella in patients with total or partial knee arthroplasty. We respectively analysed plain-film radiographs, as well as ultrasound images when acquired, in a consecutive series of 1272 patients. The mean interval from knee replacement to patellar complications was 5 years and 7 months (range, 5 months to 14 years). The complications described include fracture, instability, dislocation or luxation, necrosis of the patella, infection of the patella, erosion of the patella, patellar impingement on the prosthesis and patellar or quadricipital tendon tear. We discuss the pathological imaging findings in the patella and their differential diagnosis after knee arthroplasty. Patellar complications after knee arthroplasty are uncommon but often potentially serious.

Investigation of two families with nail-patella syndrome

International Nuclear Information System (INIS)

Adam, G.; Alzen, G.; Ittel, T.H.

1988-01-01

The radiological and clinical features of two families with a nail-patella syndrome are described. Our findings emphasize the varying expressivity of the syndrome, which has an autosomal dominant mode of inheritance and a penetrance of 100%. It is important for the radiologist to be aware of the syndrome's stigmata so that renal failure can be detected as early as possible after the diagnosis of skeletal dysplasia. (orig.) [de

Runners with Patellofemoral Pain Exhibit Greater Peak Patella Cartilage Stress Compared to Pain-Free Runners.

Science.gov (United States)

Liao, Tzu-Chieh; Keyak, Joyce H; Powers, Christopher M

2018-02-27

The purpose of this study is to determine whether recreational runners with patellofemoral pain (PFP) exhibit greater peak patella cartilage stress compared to pain-free runners. A secondary purpose was to determine the kinematic and/or kinetic predictors of peak patella cartilage stress during running. Twenty-two female recreational runners participated (12 with PFP and 10 pain-free controls). Patella cartilage stress profiles were quantified using subject-specific finite element models simulating the maximum knee flexion angle during stance phase of running. Input parameters to the finite element model included subject-specific patellofemoral joint geometry, quadriceps muscle forces, and lower extremity kinematics in the frontal and transverse planes. Tibiofemoral joint kinematics and kinetics were quantified to determine the best predictor of stress using stepwise regression analysis. Compared to the pain-free runners, those with PFP exhibited greater peak hydrostatic pressure (PFP vs. control, 21.2 ± 5.6 MPa vs. 16.5 ± 4.6 MPa) and maximum shear stress (11.3 ± 4.6 MPa vs. 8.7 ± 2.3 MPa). Knee external rotation was the best predictor of peak hydrostatic pressure and peak maximum shear stress (38% and 25% of variances, respectively) followed by the knee extensor moment (21% and 25% of variances, respectively). Runners with PFP exhibit greater peak patella cartilage stress during running compared to pain-free individuals. The combination of knee external rotation and a high knee extensor moment best predicted elevated peak stress during running.

A retrospective study on incidence of lameness in domestic animals

Directory of Open Access Journals (Sweden)

A. Mohsina

2014-08-01

Full Text Available Aim: To study the incidence of lameness among different species of animals presented to the Veterinary Polyclinic, Indian Veterinary Research Institute, Izatnagar. Materials and Methods: Outpatient department (OPD records for the period from January 2006 to December 2010 were referred and information was collected regarding number of lameness in different species, breeds, type of injury, limb affected, gender, age at onset, treatment offered, outcome and any reoccurrence. In this study, fractured cases were not included. Results: The incidence of lameness among different species were recorded: canine (56%, equine (21%, caprine (7%, feline (3%, cattle (7%, buffalo (5.47%, sheep (0.6%, monkey (0.39% and swine (0.19%. In dog, the different conditions were reported with hind quarter weakness recording 55% of lameness followed by right hind limb lameness (14.7%, left hind limb lameness (12.6%, left forelimb lameness (12%, hip dislocation (6.3% and hip dysplasia (4.2%. In caprines, important causes of lameness were right forelimb lameness (23%, right hind limb lameness (12%, left forelimb lameness (12%, posterior paresis (9%, left shoulder dislocation (14% and right shoulder dislocation (6%. In cattle, 34.28% of cases with right hind limb lameness, 28.5% cases were due to HQW, 14.28% had hip dysplasia, 8.57% suffered left hind limb lameness, 6% cases were recorded with obturator nerve paralysis and 8.57% cases suffered contracted tendon in calves. In buffaloes, cases reported were right carpal arthritis, foot rot and left hind limb lameness (14.28% each, due to bilateral upward luxation of patella and due bilateral purulent wound in stifle (18% each and hip dislocation (21.4%. In equines, lameness were reported with right hind limb affection (13%, left forelimb affection (11%, right forelimb affection (17%, 4% each due to disease of right shoulder, HQW and both forelimb affection, lateral dislocation of patella (3%, affection of both hind limbs (9%, 5

Keblish's lateral surgical approach enhances patellar tilt in valgus knee arthroplasty

Directory of Open Access Journals (Sweden)

José Roberto Tonelli Filho

Full Text Available ABSTRACT OBJECTIVE: To compare the clinical and radiological outcomes of conventional medial and lateral approaches for total knee replacement in the valgus osteoarthritic knee. METHODS: In this randomized controlled trial, 21 patients with valgus knee osteoarthritis were randomized to total knee replacement through medial or lateral approach. The primary outcome was radiographic patellar tilt. Secondary outcomes were visual analog scale of pain, postoperative levels of hemoglobin, and clinical aspect of the operative wound. RESULTS: There were no differences between the groups regarding other clinical variables. Mean lateral tilt of the patella was 3.1 degrees (SD ± 5.3 in the lateral approach group and 18 degrees (SD ± 10.2 in the medial approach group (p = 0.02. There were no differences regarding the secondary outcomes. CONCLUSION: Lateral approach provided better patellar tilt following total knee replacement in valgus osteoarthritic knee.

Botulinum Neurotoxin Injection for the Treatment of Recurrent Temporomandibular Joint Dislocation with and without Neurogenic Muscular Hyperactivity

Directory of Open Access Journals (Sweden)

Kazuya Yoshida

2018-04-01

Full Text Available The aim of this study was to compare treatment outcomes following intramuscular injection of botulinum neurotoxin (BoNT in patients with recurrent temporomandibular joint dislocation, with and without muscle hyperactivity due to neurological diseases. Thirty-two patients (19 women and 13 men, mean age: 62.3 years with recurrent temporomandibular joint dislocation were divided into two groups: neurogenic (8 women and 12 men and habitual (11 women and 1 man. The neurogenic group included patients having neurological disorders, such as Parkinson’s disease or oromandibular dystonia, that are accompanied by muscle hyperactivity. BoNT was administered via intraoral injection to the inferior head of the lateral pterygoid muscle. In total, BoNT injection was administered 102 times (mean 3.2 times/patient. The mean follow-up duration was 29.5 months. The neurogenic group was significantly (p < 0.001 younger (47.3 years than the habitual group (84.8 years and required significantly (p < 0.01 more injections (4.1 versus 1.7 times to achieve a positive outcome. No significant immediate or delayed complications occurred. Thus, intramuscular injection of BoNT into the lateral pterygoid muscle is an effective and safe treatment for habitual temporomandibular joint dislocation. More injections are required in cases of neurogenic temporomandibular joint dislocation than in those of habitual dislocation without muscle hyperactivity.

Dislocation Dynamics During Plastic Deformation

CERN Document Server

Messerschmidt, Ulrich

2010-01-01

The book gives an overview of the dynamic behavior of dislocations and its relation to plastic deformation. It introduces the general properties of dislocations and treats the dislocation dynamics in some detail. Finally, examples are described of the processes in different classes of materials, i.e. semiconductors, ceramics, metals, intermetallic materials, and quasicrystals. The processes are illustrated by many electron micrographs of dislocations under stress and by video clips taken during in situ straining experiments in a high-voltage electron microscope showing moving dislocations. Thus, the users of the book also obtain an immediate impression and understanding of dislocation dynamics.

The coupled effects of crouch gait and patella alta on tibiofemoral and patellofemoral cartilage loading in children.

Science.gov (United States)

Brandon, Scott C E; Thelen, Darryl G; Smith, Colin R; Novacheck, Tom F; Schwartz, Michael H; Lenhart, Rachel L

2018-02-01

Elevated tibiofemoral and patellofemoral loading in children who exhibit crouch gait may contribute to skeletal deformities, pain, and cessation of walking ability. Surgical procedures used to treat crouch frequently correct knee extensor insufficiency by advancing the patella. However, there is little quantitative understanding of how the magnitudes of crouch and patellofemoral correction affect cartilage loading in gait. We used a computational musculoskeletal model to simulate the gait of twenty typically developing children and fifteen cerebral palsy patients who exhibited mild, moderate, and severe crouch. For each walking posture, we assessed the influence of patella alta and baja on tibiofemoral and patellofemoral cartilage contact. Tibiofemoral and patellofemoral contact pressures during the stance phase of normal gait averaged 2.2 and 1.0 MPa. Crouch gait increased pressure in both the tibofemoral (2.6-4.3 MPa) and patellofemoral (1.8-3.3 MPa) joints, while also shifting tibiofemoral contact to the posterior tibial plateau. For extended-knee postures, normal patellar positions (Insall-Salvatti ratio 0.8-1.2) concentrated contact on the middle third of the patellar cartilage. However, in flexed knee postures, both normal and baja patellar positions shifted pressure toward the superior edge of the patella. Moving the patella into alta restored pressure to the middle region of the patellar cartilage as crouch increased. This work illustrates the potential to dramatically reduce tibiofemoral and patellofemoral cartilage loading by surgically correcting crouch gait, and highlights the interaction between patella position and knee posture in modulating the location of patellar contact during functional activities. Copyright © 2017 Elsevier B.V. All rights reserved.

Trans-triquetral Perilunate fracture dislocation

OpenAIRE

John-Henry Rhind; Abhinav Gulihar; Andrew Smith

2018-01-01

Perilunate dislocations and perilunate fracture dislocations are rare and serious injuries. Perilunate dislocations represent less than 10% of all carpal injuries of which 61% represent transcaphoid fractures. Because of their rarity, up to 25% of perilunate dislocations are initially missed on first assessment. We present the case of a 66-year-old-gentleman who sustained an isolated trans-triquetral perilunate fracture dislocation while walking his dog. This was diagnosed in the emergency de...

A continuum theory of edge dislocations

Science.gov (United States)

Berdichevsky, V. L.

2017-09-01

Continuum theory of dislocation aims to describe the behavior of large ensembles of dislocations. This task is far from completion, and, most likely, does not have a "universal solution", which is applicable to any dislocation ensemble. In this regards it is important to have guiding lines set by benchmark cases, where the transition from a discrete set of dislocations to a continuum description is made rigorously. Two such cases have been considered recently: equilibrium of dislocation walls and screw dislocations in beams. In this paper one more case is studied, equilibrium of a large set of 2D edge dislocations placed randomly in a 2D bounded region. The major characteristic of interest is energy of dislocation ensemble, because it determines the structure of continuum equations. The homogenized energy functional is obtained for the periodic dislocation ensembles with a random contents of the periodic cell. Parameters of the periodic structure can change slowly on distances of order of the size of periodic cells. The energy functional is obtained by the variational-asymptotic method. Equilibrium positions are local minima of energy. It is confirmed the earlier assertion that energy density of the system is the sum of elastic energy of averaged elastic strains and microstructure energy, which is elastic energy of the neutralized dislocation system, i.e. the dislocation system placed in a constant dislocation density field making the averaged dislocation density zero. The computation of energy is reduced to solution of a variational cell problem. This problem is solved analytically. The solution is used to investigate stability of simple dislocation arrays, i.e. arrays with one dislocation in the periodic cell. The relations obtained yield two outcomes: First, there is a state parameter of the system, dislocation polarization; averaged stresses affect only dislocation polarization and cannot change other characteristics of the system. Second, the structure of

Pulsatile and steady-state hemodynamics of the human patella bone by diffuse optical spectroscopy

International Nuclear Information System (INIS)

Farzam, Parisa; Zirak, Peyman; Durduran, Turgut; Binzoni, Tiziano

2013-01-01

The cardiac cycle related pulsatile behavior of the absorption and scattering coefficients of diffuse light and the corresponding alterations in hemoglobin concentrations in the human patella was studied. The pulsations in scattering is considerably smaller than absorption. The difference in amplitude of absorption coefficient pulsations for different wavelengths was translated to pulsations in oxygenated and deoxygenated hemoglobin, which leads to strong pulsations in the total hemoglobin concentration and oxygen saturation. The physiological origin of the observed signals was confirmed by applying a thigh-cuff. Moreover, we have investigated the optical and physiological properties of the patella bone and their changes in response to arterial cuff occlusion. (paper)

Pulsatile and steady-state hemodynamics of the human patella bone by diffuse optical spectroscopy.

Science.gov (United States)

Farzam, Parisa; Zirak, Peyman; Binzoni, Tiziano; Durduran, Turgut

2013-08-01

The cardiac cycle related pulsatile behavior of the absorption and scattering coefficients of diffuse light and the corresponding alterations in hemoglobin concentrations in the human patella was studied. The pulsations in scattering is considerably smaller than absorption. The difference in amplitude of absorption coefficient pulsations for different wavelengths was translated to pulsations in oxygenated and deoxygenated hemoglobin, which leads to strong pulsations in the total hemoglobin concentration and oxygen saturation. The physiological origin of the observed signals was confirmed by applying a thigh-cuff. Moreover, we have investigated the optical and physiological properties of the patella bone and their changes in response to arterial cuff occlusion.

Osteochondral fragmentation of the distal aspect of the patella in horses

International Nuclear Information System (INIS)

McIlwraith, C.W.

1990-01-01

A condition characterised by osteochondral fragmentation of the distal aspect of the patella in 15 horses is described. The problem was unilateral in six horses and bilateral in nine. There were eight Quarterhorses, three Thoroughbreds, two American Saddlebreds, one American Paint and one Warmblood-Thoroughbred cross. A previous medial patellar desmotomy had been performed on 12 of the 15 horses. The condition manifested as hindlimb lameness and stiffness ranging from mild to severe. There was fibrous thickening in the stifle area in the 12 cases with a previous medial patellar desmotomy, and synovial effusion in seven of 12 cases. Synovial effusion was present in two of the three cases in which a previous medial patellar desmotomy was not performed. The radiographic changes included bony fragmentation, spurring (with or without an associated subchondral defect), subchondral roughening and subchondral lysis of the distal aspect of the patella. All horses were treated with arthroscopic surgery. The lesions at arthroscopy varied from flaking, fissuring, undermining or fragmentation of the articular cartilage to fragmentation or lysis of the bone at the distal aspect of the patella. The subchondral bone was involved in all cases that had a previous medial patellar desmotomy. Of the 12 horses that had a previous medial patellar desmotomy, eight became sound at their intended use, one was sold in training without problems, one is in early training without problems, one never improved and one is in convalescence. Of the three that did not have a patellar desmotomy, two performed their intended use well but one was unsatisfactory

transverse patella fracture in a ten year old boy: case report

African Journals Online (AJOL)

report a case of a transverse patella fracture in a ten year old boy. He presented with ... fall, he reported that he had pain and swelling which resolved ... radiographs of the patient's right (normal) knee. Figure 1 ... the limb splinted in a back slab.

Frenkel defect absorption on dislocations and dislocation discharge rate. Modeling determination of the absorption zone

International Nuclear Information System (INIS)

Mikhlin, Eh.Ya.

1988-01-01

A situation connected with the fact that evaluations of dislocation discharge strength which somehow or other are based on the elasticity theory in the dislocation nucleus or near it, do not lead to results complying with experimental data, is discussed. Bases of the alternative approach to this problem consisting in direct investigation into the process of Frenkel defect absorption on dislocation by its computerized simulation at the microscopic level are also presented. Methods of investigation and results are described using α dislocation in iron-alpha as an example. The concept of zones of vacancy and interstitial atom absorption on dislocation is discussed. It is shown that a spontaneous transition, performed by any of these defects near a dislocation is not always identical to absorption and usually appears to be only a part of a multistage process leading to the defect disappearance. Potential relief characteristics for vacancy movement near the dislocation are found. An area wide enough in a transverse direction is found around the dislocation. Vacncies reaching this area can be easily transported to places of their disappearance. Therefore the vacancy entry to this area is equivalent to the absorption. the procedure of simulating the atomic structure of a crystallite containing a dislocation with a step is described. Positions from which these defects perform spontaneous transitions, reaching the disappearance places are found on the dislocation near the step

Radiographic Shape of Foot With Second Metatarsophalangeal Joint Dislocation Associated With Hallux Valgus.

Science.gov (United States)

Kokubo, Tetsuro; Hashimoto, Takeshi; Suda, Yasunori; Waseda, Akeo; Ikezawa, Hiroko

2017-12-01

Second metatarsophalangeal (MTP) joint dislocation is associated with hallux valgus, and the treatment of complete dislocation can be difficult. The purpose of this study was to radiographically clarify the characteristic foot shape in the presence of second MTP joint dislocation. Weight-bearing foot radiographs of the 268 patients (358 feet) with hallux valgus were examined. They were divided into 2 groups: those with second MTP joint dislocation (study group = 179 feet) and those without dislocation (control group = 179 feet). Parameters measured included the hallux valgus angle (HVA), first-second intermetatarsal angle (IMA), second MTP joint angle, hallux interphalangeal angle (IPA), second metatarsal protrusion distance (MPD), metatarsus adductus angle (MAA), and the second metatarsal declination angle (2MDA). Furthermore, the dislocation group was divided into 3 subgroups according to second toe deviation direction: group M (medial type), group N (neutral type), and group L (lateral type). The IPA and the 2MDA were significantly greater in the study group than in the control group. By multiple comparison analysis, the IMA was greatest in group M and smallest in group L. The IPA was smaller and 2MDA greater in group N than in group L. The HVA and MAA in group L were greatest, and MPD in group L was smallest. The patients with second MTP joint dislocation associated with hallux valgus had greater hallux interphalangeal joint varus and a second metatarsal more inclined than with hallux valgus alone. The second toe deviated in a different direction according to the foot shape. Level III, retrospective comparative study.

Velocities of dislocation groups in very thin neutron-irradiated copper single crystals measured by slip line cinematography

Energy Technology Data Exchange (ETDEWEB)

Potthoff, H.H. (Technische Univ. Braunschweig (Germany, F.R.). Inst. fuer Metallphysik und Nukleare Festkoerperphysik)

1983-05-16

Slip line development on very thin flat single crystals of neutron-irradiated Cu (thickness down to only 15 to 20 ..mu..m, orientation for single glide, yield region, room temperature) is recorded by high-speed cinematography during tensile deformation. In such very thin crystals glide dislocations on the slip plane must be arranged in a rather simple way. Drops in tensile load occuring during initiation of single slip lines at the Lueders band front indicate that in the beginning of a slip line development dislocation groups traverse the whole glide plane in very short times. Evaluating the data measured for the slip line growth v/sub s/ >= 10 cm/s is found for screw dislocations and v/sub e/ >= v/sub s/ for edge dislocations. For later stages on thin crystals and for all stages on thick crystals (>= several 100 ..mu..m) slip line development is much slower and slip line show many cross slip events which then appear to control the mean velocity of the dislocations.

Lateral patellar luxation: magnetic resonance findings

International Nuclear Information System (INIS)

Armesto, V.; Pulpeiro, J.R.

1995-01-01

The objective of this article is to present the magnetic resonance (MR) findings associated with lateral patellar luxation. The series consisted of eight patients, all of whom presented joint effusion, damage to the medical retinaculum and cortical contusion or fracture of medical aspect of the patella or of anterolateral surface of the outer condyle. Five patients also presented patellar sub luxation. Diagnosis depends on the technique employed, with axial planes being very useful. Thus, it is recommended that they be used as the standard plane, especially in pathologies that are clinically unsuspicious as in this case. MR can also provide information that leads to surgical treatment rather than the standard conservative treatment. (Author)

Mechanisms for decoration of dislocations by small dislocation loops under cascade damage conditions

DEFF Research Database (Denmark)

Trinkaus, H.; Singh, B.N.; Foreman, A.J.E.

1997-01-01

. This effect may arise as a result of either (a) migration and enhanced agglomeration of single SIAs in the form of loops in the strain field of the dislocation or (b) glide and trapping of SIA loops (produced directly in the cascades) in the strain field of the dislocation, In the present paper, both...... of these possibilities are examined. It is shown that the strain field of the dislocation causes a SIA depletion in the compressive as well as in the dilatational region resulting in a reduced rather than enhanced agglomeration of SIAs. (SIA depletion may, however, induce enhanced vacancy agglomeration near dislocations...

Primary patellar dislocations without surgical stabilization or recurrence: how well are these patients really doing?

Science.gov (United States)

Magnussen, Robert A; Verlage, Megan; Stock, Elizabeth; Zurek, Lauren; Flanigan, David C; Tompkins, Marc; Agel, Julie; Arendt, Elizabeth A

2017-08-01

While a significant research has gone into identifying patients at highest risk of recurrence following primary patellar dislocation, there has been little work exploring the outcomes of patients who do not have a recurrent patellar dislocation. We hypothesize that patients without recurrent dislocation episodes will exhibit significantly higher KOOSs than those who suffer recurrent dislocations, but lower scores than published age-matched normative data. A retrospective review of patients with nonoperatively treated primary lateral patellar dislocations was carried out, and patients were contacted at a mean of 3.4 years (range 1.3-5.5 years) post-injury. Information regarding subsequent treatment and recurrent dislocations along with patient-reported outcome scores and activity level was collected. One hundred and eleven patients (29.8 %) of 373 eligible patients agreed to study participation, seven of whom were excluded because they underwent subsequent patellar stabilization surgery on the index knee. Seventy-six patients (73.1 %) reported no further dislocation events, and the mean KOOS subscales at follow-up were: symptoms-80.2 ± 18.8, pain-81.8 ± 16.2, ADL-88.7 ± 15.9, sport/recreation-72.1 ± 24.4, and QOL-63.9 ± 23.8 at a mean follow-up of 3.3 years (range 1.3-5.5 years). No significant differences in any of the KOOS subscales were noted between these patients and the group that reported recurrent patellar dislocations. Only 26.4 % of the patients without further dislocations reported they were able to return to desired sport activities without limitations following their dislocation. Patients who do not report recurrent patellar dislocations following nonoperative treatment of primary patellar dislocations are in many cases limited by this injury 3 years following the initial dislocation event. Retrospective cohort study, Level III.

Dislocation-cavity interaction in Fe: a comparison between molecular dynamics and dislocation dynamics

International Nuclear Information System (INIS)

Hafez Haghighat, S.M.; Schaeublin, R.; Fivel, M.C.

2007-01-01

Full text of publication follows: multi-scale modeling, including molecular dynamics (MD) and discrete dislocation dynamics (DDD) methods, appears as a significant tool for the description of plasticity and mechanical properties of materials. This research is on the investigation of the subsequence effects of irradiation on the plasticity of pure Fe and focuses on the interaction of a single dislocation and a spherical cavity, as void or He bubble. Extensive MD simulations of the interaction under imposed strain rate [1, 2] have shown that various temperatures and cavity sizes result in different release stresses depending on dislocation bow out. It appears that a temperature increase and cavity size decrease reduce the cavity strength. MD simulation shows that the elastic field around the cavity is largely anisotropic. This anisotropy may influence the way the dislocation unpins from the cavity. Following the MD simulations, the interaction of a single dislocation and a spherical cavity is now simulated using a DDD discrete dislocation dynamics model. The simulation accounts for the non-Schmidt effect induced by the bcc structure of Fe through local rules derived from MD simulations [3]. The cavity is introduced in the simulation by computing the image forces using a finite element technique. The effective stress applied on the dislocation is then obtained as the superimposition of the applied stress field, the image stress field and the internal stresses. Note that such a model only uses elasticity theory and no core effect of dislocations is taken into account. One of the objectives of this work is to check whether elasticity is responsible of the behaviour observed by MD. Several cases are tested. First an edge dislocation in a (110) plane is pushed against the cavity under a pure shear loading. The local reaction of the dislocations and the cavity are compared to the MD simulations. Then, the case of a screw dislocation is studied. Finally, other loading

Secondary aneurysmal bone cyst following chondroblastoma of the patella

Directory of Open Access Journals (Sweden)

Tomoyuki Kato

2013-09-01

Full Text Available Aneurysmal bone cyst (ABC is a rare benign cystic lesion of the bone that composes 1-2% of the entire bone tumors. Some are idiopathic, and some occur secondary to other tumors such as giant cell tumor and chondroblastoma. In this article, we report the clinical, radiographic, and histological findings of a secondary ABC following chondroblastoma of the patella with a review of the literature.

Discrete dislocation modelling of submicron indentation

NARCIS (Netherlands)

Widjaja, A; Van der Giessen, E; Needleman, A

2005-01-01

Indentation of a planar single crystal by a circular rigid indenter is analyzed using discrete dislocation plasticity. The crystal has three slip systems and is initially dislocation-free, but edge dislocations can nucleate from point sources inside the crystal. The lattice resistance to dislocation

Dislocated Shoulder: Symptoms and Causes

Science.gov (United States)

... caused by: Sports injuries. Shoulder dislocation is a common injury in contact sports, such as football and hockey, and in sports that may involve falls, such as downhill skiing, gymnastics and volleyball. ... is a common source of dislocation. Falls. You may dislocate your ...

Microscopically derived free energy of dislocations

NARCIS (Netherlands)

Kooiman, M.; Hütter, M.; Geers, M.G.D.

2015-01-01

The dynamics of large amounts of dislocations is the governing mechanism in metal plasticity. The free energy of a continuous dislocation density profile plays a crucial role in the description of the dynamics of dislocations, as free energy derivatives act as the driving forces of dislocation

Effects of dislocations on polycrystal anelasticity

Science.gov (United States)

Sasaki, Y.; Takei, Y.; McCarthy, C.; Suzuki, A.

2017-12-01

Effects of dislocations on the seismic velocity and attenuation have been poorly understood, because only a few experimental studies have been performed [Guéguen et al., 1989; Farla et al., 2012]. By using organic borneol as a rock analogue, we measured dislocation-induced anelasticity accurately over a broad frequency range. We first measured the flow law of borneol aggregates by uniaxial compression tests under a confining pressure of 0.8 MPa. A transition from diffusion creep (n = 1) to dislocation creep (n = 5) was captured at about σ = 1 MPa (40°C-50°C). After deforming in the dislocation creep regime, sample microstructure showed irregular grain shape consistent with grain boundary migration. Next, we conducted three creep tests at σ = 0.27 MPa (diffusion creep regime), σ = 1.3 MPa and σ = 1.9 MPa (dislocation creep regime) on the same sample in increasing order, and measured Young's modulus E and attenuation Q-1 after each creep test by forced oscillation tests. The results show that as σ increased, E decreased and Q-1 increased. These changes induced by dislocations, however, almost fully recovered during the forced oscillation tests performed for about two weeks under a small stress (σ = 0.27 MPa) due to the dislocation recovery (annihilation). In order to constrain the time scale of the dislocation-induced anelastic relaxation, we further measured Young's modulus E at ultrasonic frequency before and after the dislocation creep and found that E at 106 Hz is not influenced by dislocations. Because E at 100 Hz is reduced by dislocations by 10%, the dislocation-induced anelastic relaxation occurs mostly between 102-106 Hz which is at a higher frequency than grain-boundary-induced anelasticity. To avoid dislocation recovery during the anelasticity measurement, we are now trying to perform an in-situ measurement of anelasticity while simultaneously deforming under a high stress associated with dislocation creep. The combination of persistent creep

Recurrent spontaneous hip dislocation in a patient with neurofibromatosis type 1: a case report

Directory of Open Access Journals (Sweden)

Harty James A

2011-03-01

Full Text Available Abstract Introduction Neurofibromatosis type-1 is a common genetic disorder which often affects the skeleton. Skeletal manifestations of neurofibromatosis type-1 include scoliosis, congenital pseudarthrosis of the tibia and intraosseous cystic lesions. Dislocation of the hip associated with neurofibromatosis type-1 is a rare occurrence and is underreported in the literature. Case presentation We report a case of hip dislocation resulting from an intra-articular neurofibroma in an 18-year-old Caucasian woman following minor trauma. This was originally suggested by the abnormalities on early radiographs of her pelvis and later confirmed with computed tomography and magnetic resonance imaging. Treatment was successful with skeletal traction for six weeks with no further hip dislocations at a 12-year follow-up. Conclusion This case illustrates the radiological features of this rare complication of neurofibromatosis type-1 using the modalities of plain radiograph, magnetic resonance imaging and computed tomography reconstruction. The radiological images give a clear insight into the mechanism by which neurofibromatosis type-1 leads to hip dislocation. It also demonstrates one treatment option with excellent results on long-term follow-up.

Traumatic hip dislocations in children

International Nuclear Information System (INIS)

Minhas, M.S.

2010-01-01

Objectives: To evaluate clinical features, treatment and relationship to the time period between dislocation, reduction and early complications of traumatic dislocation of hip in children. Methods: Case series conducted at Jinnah Post Graduate Medical Centre Karachi from July 2005 to August 2009. Children with traumatic hip dislocation up to fifteen years of age who presented in last four years were included in this study. Their clinical information, etiology, associated injuries, duration, method of reduction and early complications are evaluated through emergency room proforma and indoor record. Follow up of patient was updated in outpatient department. Results: We had eight patients, six boys and two girls. Youngest 2.4 years and eldest was 12 years with mean age of 6.2 +- 3.8 years. All presented with posterior hip dislocation. Etiology was road traffic accident in two and history of fall in remaining six patients. Average duration of time between dislocation and reduction was 19 hours range 3-72 hours. Dislocated hips were reduced under General Anaesthesia in two patients and under sedation analgesia in six patients. No complications were noted in eight cases with mean 18.75 +- 13.23 months follows up. Conclusion: Traumatic hip dislocation in children is not rare. Slight trauma causes dislocation in younger age and immediate closed reduction and Immobilization reduces complications. (author

[Classification and Treatment of Sacroiliac Joint Dislocation].

Science.gov (United States)

Tan, Zhen; Huang, Zhong; Li, Liang; Meng, Wei-Kun; Liu, Lei; Zhang, Hui; Wang, Guang-Lin; Huang, Fu-Guo

2017-09-01

To develop a renewed classification and treatment regimen for sacroiliac joint dislocation. According to the direction of dislocation of sacroiliac joint,combined iliac,sacral fractures,and fracture morphology,sacroiliac joint dislocation was classified into 4 types. Type Ⅰ (sacroiliac anterior dislocation): main fracture fragments of posterior iliac wing dislocated in front of sacroiliac joint. Type Ⅱ (sacroiliac posterior dislocation): main fracture fragments of posterior iliac wing dislocated in posterior of sacroiliac joint. Type Ⅲ (Crescent fracturedislocation of the sacroiliac joint): upward dislocation of posterior iliac wing with oblique fracture through posterior iliac wing. Type ⅢA: a large crescent fragment and dislocation comprises no more than onethird of sacroiliac joint,which is typically inferior. Type ⅢB: intermediatesize crescent fragment and dislocation comprises between one and twothirds of joint. Type ⅢC: a small crescent fragment where dislocation comprises most,but not the entire joint. Different treatment regimens were selected for different types of fractures. Treatment for type Ⅰ sacroiliac joint dislocation: anterior iliac fossa approach pry stripping reset; sacroiliac joint fixed with sacroiliac screw through percutaneous. Treatment for type Ⅱ sacroiliac joint dislocation: posterior sacroiliac joint posterior approach; sacroiliac joint fixed with sacroiliac screw under computer guidance. Treatment for type ⅢA and ⅢB sacroiliac joint dislocation: posterior sacroiliac joint approach; sacroiliac joint fixed with reconstruction plate. Treatment for type ⅢC sacroiliac joint dislocation: sacroiliac joint closed reduction; sacroiliac joint fixed with sacroiliac screw through percutaneous. Treatment for type Ⅳ sacroiliac joint dislocation: posterior approach; sacroiliac joint fixed with spinal pelvic fixation. Results of 24 to 72 months patient follow-up (mean 34.5 months): 100% survival,100% wound healing,and 100

Quasicontinuum analysis of dislocation-coherent twin boundary interaction to provide local rules to discrete dislocation dynamics

Science.gov (United States)

Tran, H.-S.; Tummala, H.; Duchene, L.; Pardoen, T.; Fivel, M.; Habraken, A. M.

2017-10-01

The interaction of a pure screw dislocation with a Coherent Twin Boundary Σ3 in copper was studied using the Quasicontinuum method. Coherent Twin Boundary behaves as a strong barrier to dislocation glide and prohibits slip transmission across the boundary. Dislocation pileup modifies the stress field at its intersection with the Grain Boundary (GB). A methodology to estimate the strength of the barrier for a dislocation to slip across CTB is proposed. A screw dislocation approaching the boundary from one side either propagates into the adjacent twin grain by cutting through the twin boundary or is stopped and increases the dislocation pileup amplitude at the GB. Quantitative estimation of the critical stress for transmission was performed using the virial stress computed by Quasicontinuum method. The transmission mechanism and critical stress are in line with the literature. Such information can be used as input for dislocation dynamic simulations for a better modeling of grain boundaries.

Hybrid dislocated control and general hybrid projective dislocated synchronization for the modified Lue chaotic system

International Nuclear Information System (INIS)

Xu Yuhua; Zhou Wuneng; Fang Jianan

2009-01-01

This paper introduces a modified Lue chaotic system, and some basic dynamical properties are studied. Based on these properties, we present hybrid dislocated control method for stabilizing chaos to unstable equilibrium and limit cycle. In addition, based on the Lyapunov stability theorem, general hybrid projective dislocated synchronization (GHPDS) is proposed, which includes complete dislocated synchronization, dislocated anti-synchronization and projective dislocated synchronization as its special item. The drive and response systems discussed in this paper can be strictly different dynamical systems (including different dimensional systems). As examples, the modified Lue chaotic system, Chen chaotic system and hyperchaotic Chen system are discussed. Numerical simulations are given to show the effectiveness of these methods.

Hybrid dislocated control and general hybrid projective dislocated synchronization for the modified Lue chaotic system

Energy Technology Data Exchange (ETDEWEB)

Xu Yuhua [College of Information Science and Technology, Donghua University, Shanghai 201620 (China) and Department of Maths, Yunyang Teacher' s College, Hubei 442000 (China)], E-mail: yuhuaxu2004@163.com; Zhou Wuneng [College of Information Science and Technology, Donghua University, Shanghai 201620 (China)], E-mail: wnzhou@163.com; Fang Jianan [College of Information Science and Technology, Donghua University, Shanghai 201620 (China)

2009-11-15

This paper introduces a modified Lue chaotic system, and some basic dynamical properties are studied. Based on these properties, we present hybrid dislocated control method for stabilizing chaos to unstable equilibrium and limit cycle. In addition, based on the Lyapunov stability theorem, general hybrid projective dislocated synchronization (GHPDS) is proposed, which includes complete dislocated synchronization, dislocated anti-synchronization and projective dislocated synchronization as its special item. The drive and response systems discussed in this paper can be strictly different dynamical systems (including different dimensional systems). As examples, the modified Lue chaotic system, Chen chaotic system and hyperchaotic Chen system are discussed. Numerical simulations are given to show the effectiveness of these methods.

Coarse-grained elastodynamics of fast moving dislocations

International Nuclear Information System (INIS)

Xiong, Liming; Rigelesaiyin, Ji; Chen, Xiang; Xu, Shuozhi; McDowell, David L.; Chen, Youping

2016-01-01

The fundamental mechanism of dynamic plasticity in metallic materials subjected to shock loading remains unclear because it is difficult to obtain the precise information of individual fast moving dislocations in metals from the state-of-the-art experiments. In this work, the dynamics of sonic dislocations in anisotropic crystalline materials is explored through a concurrent atomistic-continuum modeling method. We make a first attempt to characterize the complexity of nonuniformly moving dislocations in anisotropic crystals from atomistic to microscale, including the energy intensities as well as the wavelengths of acoustic phonons emitted from sonic dislocations, and the velocity-dependent stress fluctuations around the core of nonuniformly moving dislocations. Instantaneous dislocation velocities and phonon drag effects on the dislocation motions are quantified and analyzed. Mach cones in a V-shaped pattern of the phonon wave-fronts are observed in the wake of the sonic dislocations. Analysis of simulation results based on a wavelet transform show that the faster a dislocation is moving, the longer the emitted phonon wavelength. The dislocation velocity drops dramatically with the occurrence of the interactions between dislocations and phonon waves reflected from the boundaries of specimens. The concurrent atomistic-continuum modeling framework is demonstrated to be the first multiscale method that explicitly treats the strong coupling between the long-range elastic fields away from the dislocation core, the highly nonlinear time-dependent stress field within the core, and the evolutions of the atomic-scale dislocation core structures. As such, it is shown that this method is capable in predicting elastodynamics of dislocations in the presence of inertia effects associated with sonic dislocations in micron-sized anisotropic crystalline materials from the atomic level, which is not directly accessible to the recent elastodynamic discrete dislocation model.

Epidemiology of Isolated Acromioclavicular Joint Dislocation

Directory of Open Access Journals (Sweden)

Claudio Chillemi

2013-01-01

Full Text Available Background. Acromioclavicular (AC joint dislocation is a common shoulder problem. However, information about the basic epidemiological features of this condition is scarce. The aim of this study is to analyze the epidemiology of isolated AC dislocation in an urban population. Materials and Methods. A retrospective database search was performed to identify all patients with an AC dislocation over a 5-year period. Gender, age, affected side and traumatic mechanism were taken into account. X-rays were reviewed by two of the authors and dislocations were classified according to the Rockwood’s criteria. Results. A total of 108 patients, with a mean age of 37.5 years were diagnosed with AC dislocation. 105 (97.2% had an isolated AC dislocation, and 3 (2.8% were associated with a clavicle fracture. The estimated incidence was 1.8 per 10000 inhabitants per year and the male-female ratio was 8.5 : 1. 50.5% of all dislocations occurred in individuals between the ages of 20 and 39 years. The most common traumatic mechanism was sport injury and the most common type of dislocation was Rockwood type III. Conclusions. Age between 20 and 39 years and male sex represent significant demographic risk factors for AC dislocation.

Outcome and clinical signs of arthroscopically graded patellar chondromalacia with or without lateral release.

Science.gov (United States)

Korkala, O L; Isotalo, T M; Lavonius, M I; Niskanen, R O

1995-01-01

In a follow-up study of 67 patients with an arthroscopically diagnosed patellar chondromalacia, we compared the results of plain conservative treatment with those after an open lateral retinacular release. The mean follow-up was 35 months. In Grade I chondromalacia the lateral release did not affect the result, which was in all cases good or excellent. In Grade II to IV chondromalacia the lateral release appeared beneficial, although the difference did not reach statistical significance. We also examined the validity of three clinical signs in arthroscopically verified patellar chondromalacia. Patellar inhibition and tracking tests were clearly more sensitive than the lateral apprehension test, which often gave a false negative result. If the patellar inhibition test is positive and a Grade II to IV chondromalacia of the patella is found at arthroscopy, lateral release should be considered among other procedures, like patellar shaving or patellar resurfacing.

Theory of interacting dislocations on cylinders.

Science.gov (United States)

Amir, Ariel; Paulose, Jayson; Nelson, David R

2013-04-01

We study the mechanics and statistical physics of dislocations interacting on cylinders, motivated by the elongation of rod-shaped bacterial cell walls and cylindrical assemblies of colloidal particles subject to external stresses. The interaction energy and forces between dislocations are solved analytically, and analyzed asymptotically. The results of continuum elastic theory agree well with numerical simulations on finite lattices even for relatively small systems. Isolated dislocations on a cylinder act like grain boundaries. With colloidal crystals in mind, we show that saddle points are created by a Peach-Koehler force on the dislocations in the circumferential direction, causing dislocation pairs to unbind. The thermal nucleation rate of dislocation unbinding is calculated, for an arbitrary mobility tensor and external stress, including the case of a twist-induced Peach-Koehler force along the cylinder axis. Surprisingly rich phenomena arise for dislocations on cylinders, despite their vanishing Gaussian curvature.

Velocities of dislocation groups in very thin neutron-irradiated copper single crystals measured by slip line cinematography

International Nuclear Information System (INIS)

Potthoff, H.H.

1983-01-01

Slip line development on very thin flat single crystals of neutron-irradiated Cu (thickness down to only 15 to 20 μm, orientation for single glide, yield region, room temperature) is recorded by high-speed cinematography during tensile deformation. In such very thin crystals glide dislocations on the slip plane must be arranged in a rather simple way. Drops in tensile load occuring during initiation of single slip lines at the Lueders band front indicate that in the beginning of a slip line development dislocation groups traverse the whole glide plane in very short times. Evaluating the data measured for the slip line growth v/sub s/ >= 10 cm/s is found for screw dislocations and v/sub e/ >= v/sub s/ for edge dislocations. For later stages on thin crystals and for all stages on thick crystals (>= several 100 μm) slip line development is much slower and slip line show many cross slip events which then appear to control the mean velocity of the dislocations. (author)

Relaxation strain measurements in cellular dislocation structures

International Nuclear Information System (INIS)

Tsai, C.Y.; Quesnel, D.J.

1984-01-01

The conventional picture of what happens during a stress relaxation usually involves imagining the response of a single dislocation to a steadily decreasing stress. The velocity of this dislocation decreases with decreasing stress in such a way that we can measure the stress dependence of the dislocation velocity. Analysis of the data from a different viewpoint enables us to calculate the apparent activation volume for the motion of the dislocation under the assumption of thermally activated glie. Conventional thinking about stress relaxation, however, does not consider the eventual fate of this dislocation. If the stress relaxes to a low enough level, it is clear that the dislocation must stop. This is consistent with the idea that we can determine the stress dependence of the dislocation velocity from relaxation data only for those cases where the dislocation's velocity is allowed to approach zero asymptotically, in short, for those cases where the dislocation never stops. This conflict poses a dilemma for the experimentalist. In real crystals, however, obstacles impede the dislocation's progress so that those dislocations which are stopped at a given stress will probably never resume motion under the influence of the steadily declining stress present during relaxation. Thus one could envision stress relaxation as a process of exhaustion of mobile dislocations, rather than a process of decreasing dislocation velocity. Clearly both points of view have merit and in reality both mechanisms contribute to the phenomena

Dislocation pinning effects induced by nano-precipitates during warm laser shock peening: Dislocation dynamic simulation and experiments

Science.gov (United States)

Liao, Yiliang; Ye, Chang; Gao, Huang; Kim, Bong-Joong; Suslov, Sergey; Stach, Eric A.; Cheng, Gary J.

2011-07-01

Warm laser shock peening (WLSP) is a new high strain rate surface strengthening process that has been demonstrated to significantly improve the fatigue performance of metallic components. This improvement is mainly due to the interaction of dislocations with highly dense nanoscale precipitates, which are generated by dynamic precipitation during the WLSP process. In this paper, the dislocation pinning effects induced by the nanoscale precipitates during WLSP are systematically studied. Aluminum alloy 6061 and AISI 4140 steel are selected as the materials with which to conduct WLSP experiments. Multiscale discrete dislocation dynamics (MDDD) simulation is conducted in order to investigate the interaction of dislocations and precipitates during the shock wave propagation. The evolution of dislocation structures during the shock wave propagation is studied. The dislocation structures after WLSP are characterized via transmission electron microscopy and are compared with the results of the MDDD simulation. The results show that nano-precipitates facilitate the generation of highly dense and uniformly distributed dislocation structures. The dislocation pinning effect is strongly affected by the density, size, and space distribution of nano-precipitates.

Occult posterolateral rotatory dislocation of the elbow with olecranon fracture in a child: a case report

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Fujimori Takahito

2012-09-01

Full Text Available Abstract Introduction Acute posterolateral rotator elbow dislocation in a child is rare and can be easily misdiagnosed due to immaturity of the epiphysis. This is the first case of occult posterolateral rotator elbow dislocation in combination with an olecranon fracture. We report our experience with this case, which was not diagnosed correctly by plain radiographs. Case presentation An 11-year-old Asian boy suffered severe pain and swelling of his right elbow after his outstretched arm hit a car dashboard in a motor vehicle accident. Plain radiographs showed only a minimally displaced olecranon fracture and a tiny lateral epicondylar avulsion fracture. However, stress radiographs under general anesthesia revealed severe posterolateral rotatory instability. During surgery, we found that the cartilaginous lateral epicondylar apophysis was much larger than the epicondylar fragment on the radiographs. After the lateral epicondylar osteochondral fragment and lateral collateral ligament complex were fixed, the instability disappeared. Conclusion Our experience with this case shows that it is important to check for instability with pediatric elbow fractures, because a tiny avulsion fracture was able to cause severe posterolateral rotatory instability in a child.

Primary traumatic patellar dislocation

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Tsai Chun-Hao

2012-06-01

Full Text Available Abstract Acute traumatic patellar dislocation is a common injury in the active and young adult populations. MRI of the knee is recommended in all patients who present with acute patellar dislocation. Numerous operative and non-operative methods have been described to treat the injuries; however, the ideal management of the acute traumatic patellar dislocation in young adults is still in debate. This article is intended to review the studies to the subjects of epidemiology, initial examination and management.

Chondromalacia patellae: Bone scintigraphy correlated with arthroscopic findings

International Nuclear Information System (INIS)

Kohn, H.S.; Guten, G.N.; Collier, B.D.; Veluvolu, P.; Whalen, J.P.

1987-01-01

Fifty adult sports medicine patients with anterior knee pain and other clinical findings of chondromalacia patellae unresponsive to more than 3 months of conservative therapy were evaluated with bone scintigraphy with subsequent arthroscopic correlation. There was significant correlation (Sperman rank correlation = .545, P < .001) between the intensity of increased patellar scintigraphic activity and the Metcalf grade of chondromalacia seen at arthroscopy. Bone scintigraphy also disclosed clinically unsuspected torn menisci. Bone scintigraphy contributes to accurate diagnostic evaluation and appropriate surgical planning for adult sports medicine patients with chronic anterior knee pain

Stress-free states of continuum dislocation fields : Rotations, grain boundaries, and the Nye dislocation density tensor

NARCIS (Netherlands)

Limkumnerd, Surachate; Sethna, James P.

We derive general relations between grain boundaries, rotational deformations, and stress-free states for the mesoscale continuum Nye dislocation density tensor. Dislocations generally are associated with long-range stress fields. We provide the general form for dislocation density fields whose

Molecular dynamics simulation of dislocation intersections in aluminum

International Nuclear Information System (INIS)

Li, M.; Chu, W.Y.; Qian, C.F.; Gao, K.W.; Qiao, L.J.

2003-01-01

The molecular dynamics method is used to simulate dislocation intersection in aluminum containing 1.6x10 6 atoms using embedded atom method (EAM) potential. The results show that after intersection between two right-hand screw dislocations of opposite sign there are an extended jog corresponding to a row of 1/3 vacancies in the intersected dislocation, and a trail of vacancies behind the moving dislocation. After intersection between screw dislocations of same sign, there are an extended jog corresponding to a row of 1/3 interstitials in the intersected dislocation, and a trail of interstitials behind the moving dislocation. After intersection between screw and edge dislocations with different Burgers vector, there are a constriction corresponding to one 1/3 vacancy in the edge dislocation, and no point-defects behind the screw dislocation. When a moving screw dislocation intersects an edge dislocation with the same Burgers vector, the point of intersection will split into two constrictions corresponding to one 1/3 vacancy and 1/3 interstitial, respectively. The moving screw dislocation can pass the edge dislocation only after the two constrictions, which can move along the line of intersection of the two slip planes, meet and annihilate

[The Postero-Lateral Approach--An Alternative to Closed Anterior-Posterior Screw Fixation of a Dislocated Postero-Lateral Fragment of the Distal Tibia in Complex Ankle Fractures].

Science.gov (United States)

von Rüden, C; Hackl, S; Woltmann, A; Friederichs, J; Bühren, V; Hierholzer, C

2015-06-01

The dislocated posterolateral fragment of the distal tibia is considered as a key fragment for the successful reduction of comminuted ankle fractures. The reduction of this fragment can either be achieved indirectly by joint reduction using the technique of closed anterior-posterior screw fixation, or directly using the open posterolateral approach followed by plate fixation. The aim of this study was to compare the outcome after stabilization of the dislocated posterolateral tibia fragment using either closed reduction and screw fixation, or open reduction and plate fixation via the posterolateral approach in complex ankle fractures. In a prospective study between 01/2010 and 12/2012, all mono-injured patients with closed ankle fractures and dislocated posterolateral tibia fragments were assessed 12 months after osteosynthesis. Parameters included: size of the posterolateral tibia fragment relative to the tibial joint surface (CT scan, in %) as an indicator of injury severity, unreduced area of tibial joint surface postoperatively, treatment outcome assessed by using the "Ankle Fracture Scoring System" (AFSS), as well as epidemiological data and duration of the initial hospital treatment. In 11 patients (10 female, 1 male; age 51.6 ± 2.6 years [mean ± SEM], size of tibia fragment 42.1 ± 2.5 %) the fragment fixation was performed using a posterolateral approach. Impaired postoperative wound healing occurred in 2 patients of this group. In the comparison group, 12 patients were treated using the technique of closed anterior-posterior screw fixation (10 female, 2 male; age 59.5 ± 6.7 years, size of tibia fragment 45.9 ± 1.5 %). One patient of this group suffered an incomplete lesion of the superficial peroneal nerve. Radiological evaluation of the joint surface using CT scan imaging demonstrated significantly less dislocation of the tibial joint surface following the open posterolateral approach (0.60 ± 0.20 mm) compared to the closed

Energetics of dislocation nucleation under a nanoindenter

International Nuclear Information System (INIS)

Zhang Chuanli; Xu Guanshui

2005-01-01

We present an analysis of dislocation nucleation under an idealized nanoindenter based on the variational boundary integral formulation of the Peierls-Nabarro dislocation model. By solving the embryonic dislocation profiles, corresponding to the relative displacements between the two adjacent atomic layers along the slip plane, we have determined the critical conditions for athermal dislocation nucleation as well as the activation energies required to thermally activate embryonic dislocations from their stable to unstable saddle point configurations. The effect of the size of the indenter on the energetics of dislocation nucleation is quantitatively characterized. The result is compared with a simplified analysis based on the application of the Rice model for dislocation nucleation at a crack tip

Energetics of dislocation nucleation under a nanoindenter

Energy Technology Data Exchange (ETDEWEB)

Zhang Chuanli [College of Mechanical Engineering, Yangtze University, Jingzhou, Hubei 434023 (China); Department of Mechanical Engineering, University of California, Riverside, CA 92521 (United States); Xu Guanshui [Department of Mechanical Engineering, University of California, Riverside, CA 92521 (United States)]. E-mail: guanshui.xu@ucr.edu

2005-07-25

We present an analysis of dislocation nucleation under an idealized nanoindenter based on the variational boundary integral formulation of the Peierls-Nabarro dislocation model. By solving the embryonic dislocation profiles, corresponding to the relative displacements between the two adjacent atomic layers along the slip plane, we have determined the critical conditions for athermal dislocation nucleation as well as the activation energies required to thermally activate embryonic dislocations from their stable to unstable saddle point configurations. The effect of the size of the indenter on the energetics of dislocation nucleation is quantitatively characterized. The result is compared with a simplified analysis based on the application of the Rice model for dislocation nucleation at a crack tip.

Ipsilateral open anterior hip dislocation and open posterior elbow dislocation in an adult

Directory of Open Access Journals (Sweden)

Kumar Sunil

2014-02-01

Full Text Available 【Abstract】Open anterior dislocation of the hip is a very rare injury, especially in adults. It is a hyperabduction, external rotation and extension injury. Its combination with open posterior dislocation of the elbow has not been described in English language-based medical literature. Primary resuscitation, debridement, urgent reduction of dislocation, and adequate antibiotic support resulted in good clinical outcome in our patient. At 18 months follow-up, no signs of avascular necrosis of the femoral head or infection were observed.

Elbow dislocation with intra-articular fracture: the results of operative treatment without repair of the medial collateral ligament.

Science.gov (United States)

Forthman, Christopher; Henket, Marjolijn; Ring, David C

2007-10-01

To determine the effectiveness of a protocol for the treatment of fracture-dislocations of the elbow based on the concept that, if dislocation of the elbow with associated fractures can be made to resemble a simple elbow dislocation by repairing or reconstructing the fractured structures, repair of the medial collateral ligament (MCL) will not be necessary. Over a 5-year period, a single surgeon operated on 34 patients with a posterior dislocation of the elbow associated with one or more intra-articular fractures. The mean age of these 19 men and 15 women was 48 years. Associated fractures included the capitellum, trochlea, and lateral epicondyle in 3 patients; the olecranon in 1 patient; and the radial head in 30 patients (with concomitant fracture of the coronoid process-the so-called "terrible triad" of the elbow-in 22 patients, and concomitant fracture of the coronoid and olecranon in 1 patient). Operative treatment consisted of open reduction internal fixation (ORIF) or prosthetic replacement of all fractures and reattachment of the origin of the lateral collateral ligament (LCL) complex to the lateral epicondyle. The MCL was not repaired. Two patients (1 with a terrible triad injury and 1 with fracture of the capitellum and trochlea) had postoperative instability related to noncompliance, had reconstructive procedures, and were considered failures. An average of 32 months after injury, the remaining 32 patients regained an average of 120 degrees ulnohumeral motion and 142 degrees forearm rotation. Twenty-five of 34 patients (74%) had good or excellent results according to the system of Broberg and Morrey. Patients with terrible triad injuries had an average of 117 degrees ulnohumeral motion and 137 degrees forearm rotation, and 17 of 22 patients (77%) had good or excellent results. MCL repair is unnecessary in the treatment of dislocation of the elbow with associated intra-articular fractures, provided that the articular fractures and the LCL are repaired or

Epidemiology, Etiology, and Prevention of Late IOL-Capsular Bag Complex Dislocation: Review of the Literature

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Francisco J. Ascaso

2015-01-01

Full Text Available Posterior chamber intraocular lens (PC-IOL subluxation is uncommon but represents one of the most serious complications following phacoemulsification. Late spontaneous IOL-capsular bag complex dislocation is defined as occurring three months or later following cataract surgery. Unlike early IOL dislocation, late spontaneous IOL dislocation is due to a progressive zonular dehiscence and contraction of the capsular bag many years what seemed to be uneventful surgery. In recent years, late in-the-bag IOL subluxation or dislocation has been reported with increasing frequency, having a cumulative risk of IOL dislocation following cataract extraction of 0.1% after 10 years and 1.7% after 25 years. A predisposition to zonular insufficiency and capsular contraction is identified in 90% of reviewed cases. Multiple conditions likely play a role in contributing to this zonular weakness and capsular contraction. Pseudoexfoliation is the most common risk factor, accounting for more than 50% of cases. Other associated conditions predisposing to zonular dehiscence are aging, high myopia, uveitis, trauma, previous vitreoretinal surgery, retinitis pigmentosa, diabetes mellitus, atopic dermatitis, previous acute angle-closure glaucoma attack, and connective tissue disorders. The recognition of these predisposing factors suggests a modified approach in cases at risk. We review certain measures to prevent IOL-bag complex luxation that have been proposed.

Epidemiology, Etiology, and Prevention of Late IOL-Capsular Bag Complex Dislocation: Review of the Literature.

Science.gov (United States)

Ascaso, Francisco J; Huerva, Valentín; Grzybowski, Andrzej

2015-01-01

Posterior chamber intraocular lens (PC-IOL) subluxation is uncommon but represents one of the most serious complications following phacoemulsification. Late spontaneous IOL-capsular bag complex dislocation is defined as occurring three months or later following cataract surgery. Unlike early IOL dislocation, late spontaneous IOL dislocation is due to a progressive zonular dehiscence and contraction of the capsular bag many years what seemed to be uneventful surgery. In recent years, late in-the-bag IOL subluxation or dislocation has been reported with increasing frequency, having a cumulative risk of IOL dislocation following cataract extraction of 0.1% after 10 years and 1.7% after 25 years. A predisposition to zonular insufficiency and capsular contraction is identified in 90% of reviewed cases. Multiple conditions likely play a role in contributing to this zonular weakness and capsular contraction. Pseudoexfoliation is the most common risk factor, accounting for more than 50% of cases. Other associated conditions predisposing to zonular dehiscence are aging, high myopia, uveitis, trauma, previous vitreoretinal surgery, retinitis pigmentosa, diabetes mellitus, atopic dermatitis, previous acute angle-closure glaucoma attack, and connective tissue disorders. The recognition of these predisposing factors suggests a modified approach in cases at risk. We review certain measures to prevent IOL-bag complex luxation that have been proposed.

MR findings of chondromalacia Patella : correlation of the grade and associated lesions with arthroscopic findings

International Nuclear Information System (INIS)

Chung, Yon Su; Kwon, Soon Tae; Lee, Hwan Do; Kang, Yong Soo; Byun, Ki Yong; Rhee, Kwang Jin

1998-01-01

To assess the MR findings of chondromalacia patella and correlate the grade and associated lesions with the arthroscopic findings. Twenty-five patients with pain in the anterior part of the knee underwent fat-suppressed axial and coronal T2-weighted and T2-weighted imaging, using a 10-cm field of view, and a 5-inch general purpose coil. We retrospectively assessed these findings, and the locations, grades and associated lesions, and correlated these with arthroscopic findings. We evaluated the exact location and grade of chondromalacia patella and associated lesions, as seen on MR images. These and the arthroscopic findings showed close correlation, and in cases involving this condition, MRI is thus a useful indicator of an appropriate surgical method and plan. (author). 18 refs., 5 figs

MR findings of chondromalacia Patella : correlation of the grade and associated lesions with arthroscopic findings

Energy Technology Data Exchange (ETDEWEB)

Chung, Yon Su; Kwon, Soon Tae; Lee, Hwan Do; Kang, Yong Soo; Byun, Ki Yong; Rhee, Kwang Jin [Chungnam National Univ., Taejon (Korea, Republic of). Coll. of Medicine

1998-02-01

To assess the MR findings of chondromalacia patella and correlate the grade and associated lesions with the arthroscopic findings. Twenty-five patients with pain in the anterior part of the knee underwent fat-suppressed axial and coronal T2-weighted and T2-weighted imaging, using a 10-cm field of view, and a 5-inch general purpose coil. We retrospectively assessed these findings, and the locations, grades and associated lesions, and correlated these with arthroscopic findings. We evaluated the exact location and grade of chondromalacia patella and associated lesions, as seen on MR images. These and the arthroscopic findings showed close correlation, and in cases involving this condition, MRI is thus a useful indicator of an appropriate surgical method and plan. (author). 18 refs., 5 figs.

Medial peritalar fracture dislocation of the talar body

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Jacob B. Stirton

2015-04-01

Full Text Available Peritalar fracture dislocations typically involve the talar neck and are classified according to Hawkins. To our knowledge, peritalar fracture dislocation involving the talar body has not been formally reported. In this article, we describe a case of peritalar fracture dislocation of the talar body. Keywords: Peritalar dislocation, Talus fracture, Talar body fracture dislocation, Medial subtalar dislocation

The movement of screw dislocations in tungsten

International Nuclear Information System (INIS)

Tian Xiaogeng; Woo Chungho

2004-01-01

Using Acland potential for tungsten, the movement of 1/2a screw dislocation under shear stress was investigated by molecular dynamics simulation. Equilibrated core structure was obtained by relaxation of screw dislocation with proper boundary conditions. We found that the equilibrium dislocation core has three-fold symmetry and spread out in three direction on {1 1 0} planes. The screw dislocation core could not keep the original shape when the shear stress applied. The dislocation could not move until the shear stress became large enough. The dislocation moved in zigzag when the shear stress neared the Peierls stress. When the shear stress became larger, the dislocation moved in zigzag at the beginning and than moved almost in straight line in [2-bar11] direction. The large shear stress applied, the long distance moved before the dislocation stilled in z-direction and the large velocity in y-direction

Crystalline lens dislocation secondary to bacterial endogenous endophthalmitis.

Science.gov (United States)

Sangave, Amit; Komati, Rahul; Weinmann, Allison; Samuel, Linoj; Desai, Uday

2017-09-01

To present an unusual case of endogenous endophthalmitis secondary to Group A streptococcus (GAS) that resulted in dislocation of the crystalline lens. An immunocompetent 51-year-old man presented to the emergency room (ER) with upper respiratory infection (URI) symptoms and painful right eye. He was diagnosed with URI and viral conjunctivitis and discharged on oral azithromycin and polytrim eyedrops. He returned to the ER 30 h later with sepsis and findings consistent with endophthalmitis, including light perception only vision. Ophthalmology was consulted at this time and an emergent vitreous tap and injection was performed. Both blood and vitreous cultures grew an atypical non-hemolytic variant of GAS ( Streptococcus pyogenes ). The primary source of infection was presumed to be secondary to pharyngitis or cutaneous dissemination. Final vision in the affected eye was no light perception, likely from a combination of anterior segment scarring, posterior segment damage, and hypotony. Interestingly, head computed tomography (CT) at the initial ER presentation showed normal lens position, but repeat CT at re-presentation revealed posterior dislocation of the lens. Endophthalmitis secondary to GAS has been sparsely reported in the literature, and this case highlights a unique clinical presentation. We suspect that this atypical non-hemolytic strain may have evaded detection on initial pharyngeal cultures. Additionally, we hypothesize that GAS-mediated protease release resulted in breakdown of the zonular fibers and subsequent lens dislocation. Ophthalmologists should be aware of GAS and its devastating intraocular manifestations.

Traumatic hip dislocation: early MRI findings

International Nuclear Information System (INIS)

Laorr, A.; Greenspan, A.; Anderson, M.W.; Moehring, H.D.; McKinley, T.

1995-01-01

Objective of this study was to present the spectrum of early magnetic resonance imaging (MRI) findings following traumatic dislocation of the femoral head, and to identify any associated injuries. Prospective MRI of both hips was performed on 18 patients within 5 weeks of a traumatic femoral head dislocation. The interval between the time of injury and the imaging studies ranged from 2 to 35 days. Posterior dislocation was present in 14 patients and anterior dislocation in 4 patients. In the majority of cases, we performed axial T1, coronal T1, and coronal T2 * (MPGR) sequences. MRI can effectively identify and quantify the muscle injury and joint effusion that invariably accompany traumatic hip dislocations. It is also useful for demonstrating trabecular bone contusion (trabecular injury) and iliofemoral ligament injury, which occur commonly with acute hip dislocation. (orig./VHE)

Treatment of recurrent patellar dislocation via knee arthroscopy combined with C-arm fluoroscopy and reconstruction of the medial patellofemoral ligament.

Science.gov (United States)

Li, Li; Wang, Hongbo; He, Yun; Si, Yu; Zhou, Hongyu; Wang, Xin

2018-06-01

Recurrent patellar dislocations were treated via knee arthroscopy combined with C-arm fluoroscopy, and reconstruction of the medial patellofemoral ligaments. Between October 2013 and March 2017, 52 cases of recurrent patellar dislocation [27 males and 25 females; age, 16-47 years (mean, 21.90 years)] were treated. Arthroscopic exploration was performed and patellofemoral joint cartilage injuries were repaired. It was subsequently determined whether it was necessary to release the lateral patellofemoral support belt. Pre-operative measurements were used to decide whether tibial tubercle osteotomy was required. Medial patellofemoral ligaments were reconstructed using autologous semitendinosus tendons. Smith and Nephew model 3.5 line anchors were used to double-anchor the medial patellofemoral margin. On the femoral side, the medial patellofemoral ligament was fixed using 7-cm, absorbable, interfacial compression screws. All cases were followed for 1-40 months (average, 21 months). The Q angle, tibial tuberosity trochlear groove distance, Insall-Salvati index, patellofemoral angle, lateral patellofemoral angle and lateral shift were evaluated on X-Ray images using the picture archiving and communication system. Subjective International Knee Documentation Committee (IKDC) knee joint functional scores and Lysholm scores were recorded. Post-operative fear was absent, and no patellar re-dislocation or re-fracture was noted during follow-up. At the end of follow-up, the patellofemoral angle (0.22±4.23°), lateral patellofemoral angle (3.44±1.30°), and lateral shift (0.36+0.14°) differed significantly from the pre-operative values (all, Ppatellofemoral ligament was effective.

HRTEM studies of dislocations in cubic BN

International Nuclear Information System (INIS)

Nistor, L.C.; Tendeloo, G. van; Dinca, G.

2004-01-01

The atomic structure of dislocations in cubic boron nitride has been investigated by high resolution transmission electron microscopy. Most of the perfect dislocations, screw and 60 edge, are dissociated. A 60 dislocation which was undissociated has been analysed. Computer simulation is performed in an attempt to characterise the core structure. Twinning dislocations and dislocations resulting from the intersection of stacking faults are also revealed. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

HRTEM studies of dislocations in cubic BN

Energy Technology Data Exchange (ETDEWEB)

Nistor, L.C. [National Institute for Materials Physics, P.O. Box MG-7 Magurele, 077125 Bucharest (Romania); Tendeloo, G. van [University of Antwerp, EMAT, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Dinca, G. [Dacia Synthetic Diamond Factory, Timisoara av. 5, P.O. Box 58-52, 077350 Bucharest (Romania)

2004-09-01

The atomic structure of dislocations in cubic boron nitride has been investigated by high resolution transmission electron microscopy. Most of the perfect dislocations, screw and 60 edge, are dissociated. A 60 dislocation which was undissociated has been analysed. Computer simulation is performed in an attempt to characterise the core structure. Twinning dislocations and dislocations resulting from the intersection of stacking faults are also revealed. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Rules for Forest Interactions between Dislocations

International Nuclear Information System (INIS)

Wickham, L. K.; Schwarz, K. W.; Stoelken, J. S.

1999-01-01

The dynamical interactions of dislocations existing on intersecting glide planes have been investigated using numerical simulations based on isotropic linear elastic theory. It is found that such dislocations either repel, attract and form growing junctions, or attract and form bound crossed states. Which of these occurs can be predicted from a surprisingly simple analysis of the initial configurations. The outcome is determined primarily by the angles which the dislocations initially make with the glide-plane intersection edge, and is largely independent of the initial distance between the dislocations, their initial curvature, or ambient applied stresses. The results provide a rule for dealing with forest interactions within the context of large multiple-dislocation computations. (c) 1999 The American Physical Society

Evaluation and comparison of cartilage repair tissue of the patella and medial femoral condyle by using morphological MRI and biochemical zonal T2 mapping

International Nuclear Information System (INIS)

Welsch, Goetz H.; Mamisch, Tallal C.; Quirbach, Sebastian; Trattnig, Siegfried; Zak, Lukas; Marlovits, Stefan

2009-01-01

The objective of this study was to use advanced MR techniques to evaluate and compare cartilage repair tissue after matrix-associated autologous chondrocyte transplantation (MACT) in the patella and medial femoral condyle (MFC). Thirty-four patients treated with MACT underwent 3-T MRI of the knee. Patients were treated on either patella (n = 17) or MFC (n = 17) cartilage and were matched by age and postoperative interval. For morphological evaluation, the MR observation of cartilage repair tissue (MOCART) score was used, with a 3D-True-FISP sequence. For biochemical assessment, T2 mapping was prepared by using a multiecho spin-echo approach with particular attention to the cartilage zonal structure. Statistical evaluation was done by analyses of variance. The MOCART score showed no significant differences between the patella and MFC (p ≥ 0.05). With regard to biochemical T2 relaxation, higher T2 values were found throughout the MFC (p < 0.05). The zonal increase in T2 values from deep to superficial was significant for control cartilage (p < 0.001) and cartilage repair tissue (p < 0.05), with an earlier onset in the repair tissue of the patella. The assessment of cartilage repair tissue of the patella and MFC afforded comparable morphological results, whereas biochemical T2 values showed differences, possibly due to dissimilar biomechanical loading conditions. (orig.)

Sagittal plane tilting deformity of the patellofemoral joint: a new concept in patients with chondromalacia patella.

Science.gov (United States)

Aksahin, Ertugrul; Aktekin, Cem Nuri; Kocadal, Onur; Duran, Semra; Gunay, Cüneyd; Kaya, Defne; Hapa, Onur; Pepe, Murad

2017-10-01

The aims of this study were to evaluate sagittal plane alignment in patients with chondromalacia patella via magnetic resonance imaging (MRI), analyse the relationships between the location of the patellar cartilaginous lesions and sagittal alignment and finally investigate the relationships between the sagittal plane malalignment and patellofemoral loadings using by finite element analysis. Fifty-one patients who were diagnosed with isolated modified Outerbridge grade 3-4 patellar chondromalacia based on MRI evaluation and 51 control subjects were evaluated. Chondromalacia patella patients were divided into three subgroups according to the chondral lesion location as superior, middle and inferior. The patella-patellar tendon angle (P-PT) was used for evaluation of sagittal alignment of patellofemoral joint. Each subgroup was compared with control group by using P-PT angle. To investigate the biomechanical effects of sagittal plane malpositioning on patellofemoral joint, bone models were created at 30°, 60° and 90° knee flexion by using mean P-PT angles, which obtained from patients with chondromalacia patellae and control subjects. The total loading and contact area values of the patellofemoral joints were investigated by finite element analysis. The mean age of all participants was 52.9 ± 8.2 years. The mean P-PT angle was significantly lower in chondromalacia group (142.1° ± 3.6°) compared to control group (144.5° ± 5.3°) (p = 0.008). Chondral lesions were located in superior, middle and inferior zones in 16, 20 and 15 patients, respectively. The mean P-PT angles in patients with superior (141.8 ± 2.7) and inferior subgroups (139.2 ± 2.3) were significantly lower than the values in the control group (p chondromalacia than in the control models at the same flexion degrees. There were increased loadings at 30° and 90° flexions in the sagittal patellar tilt models. This study revealed that sagittal plain malpositioning of the

Effects of dislocations on electron channeling

International Nuclear Information System (INIS)

George, Juby; Pathak, A P

2009-01-01

The phenomenon of electron channeling in a crystal affected by dislocations is considered. Earlier we had considered the quantum aspects of the positron channeling in a crystal bent by dislocations where the effects of longitudinal motion of the particle were also considered along with the transverse motion. In this paper, the effective potential for the electron case is found for the two regions of dislocation-affected channel. There is considerable shift in the potential minima due to dislocations. The frequency and the corresponding spectrum of the channeling radiation due to electrons channeling through the perfect channel and the two regions of dislocation-affected channels are calculated. The spectral distribution of radiation intensity changes with the parameters of dislocation. The continuity of wavefunctions and their derivatives is used at the three boundaries and the reflection and transmission coefficients are found using these boundary conditions in the same way as in the positron case.

Evaluation of the chondromalacia patella using a microscopy coil: comparison of the two-dimensional fast spin echo techniques and the three-dimensional fast field echo techniques.

Science.gov (United States)

Kim, Hyun-joo; Lee, Sang Hoon; Kang, Chang Ho; Ryu, Jeong Ah; Shin, Myung Jin; Cho, Kyung-Ja; Cho, Woo Shin

2011-01-01

We wanted to compare the two-dimensional (2D) fast spin echo (FSE) techniques and the three-dimensional (3D) fast field echo techniques for the evaluation of the chondromalacia patella using a microscopy coil. Twenty five patients who underwent total knee arthroplasty were included in this study. Preoperative MRI evaluation of the patella was performed using a microscopy coil (47 mm). The proton density-weighted fast spin echo images (PD), the fat-suppressed PD images (FS-PD), the intermediate weighted-fat suppressed fast spin echo images (iw-FS-FSE), the 3D balanced-fast field echo images (B-FFE), the 3D water selective cartilage scan (WATS-c) and the 3D water selective fluid scan (WATS-f) were obtained on a 1.5T MRI scanner. The patellar cartilage was evaluated in nine areas: the superior, middle and the inferior portions that were subdivided into the medial, central and lateral facets in a total of 215 areas. Employing the Noyes grading system, the MRI grade 0-I, II and III lesions were compared using the gross and microscopic findings. The sensitivity, specificity and accuracy were evaluated for each sequence. The significance of the differences for the individual sequences was calculated using the McNemar test. The gross and microscopic findings demonstrated 167 grade 0-I lesions, 40 grade II lesions and eight grade III lesions. Iw-FS-FSE had the highest accuracy (sensitivity/specificity/accuracy = 88%/98%/96%), followed by FS-PD (78%/98%/93%, respectively), PD (76%/98%/93%, respectively), B-FFE (71%/100%/93%, respectively), WATS-c (67%/100%/92%, respectively) and WATS-f (58%/99%/89%, respectively). There were statistically significant differences for the iw-FS-FSE and WATS-f and for the PD-FS and WATS-f (p chondromalacia patella.

Energy flow around a moving dislocation

International Nuclear Information System (INIS)

Koizumi, H; Kirchner, H O K

2009-01-01

A dislocation moving in a lattice emits lattice waves. We study the energy flow accompanying the lattice wave emission in a molecular dynamics situation. About two thirds of the static free energy are emitted as lattice waves from the moving dislocation. Work done by the region around the dislocation helps to initiate the motion from the unstable equilibrium state under a small applied stress, or to compensate the energy emitted as lattice waves when the dislocation makes a long distance motion under a larger stress.

Atomistic simulations of dislocation processes in copper

DEFF Research Database (Denmark)

Vegge, T.; Jacobsen, K.W.

2002-01-01

We discuss atomistic simulations of dislocation processes in copper based on effective medium theory interatomic potentials. Results on screw dislocation structures and processes are reviewed with particular focus on point defect mobilities and processes involving cross slip. For example......, the stability of screw dislocation dipoles is discussed. We show that the presence of jogs will strongly influence cross slip barriers and dipole stability. We furthermore present some new results on jogged edge dislocations and edge dislocation dipoles. The jogs are found to be extended, and simulations...

Detection and staging of chondromalacia patellae: relative efficacies of conventional MR imaging, MR arthrography, and CT arthrography.

Science.gov (United States)

Gagliardi, J A; Chung, E M; Chandnani, V P; Kesling, K L; Christensen, K P; Null, R N; Radvany, M G; Hansen, M F

1994-09-01

Chondromalacia patellae is a condition characterized by softening, fraying, and ulceration of patellar articular cartilage. We compare the sensitivity, specificity, and accuracy of conventional MR imaging, MR arthrography, and CT arthrography in detecting and staging this abnormality. Twenty-seven patients with pain in the anterior part of the knee were prospectively examined with MR imaging, including T1-weighted (650/16), proton density-weighted (2000/20), T2-weighted (2000/80), and spoiled two-dimensional gradient-recalled acquisition in the steady state (SPGR/)/35 degrees (51/10) with fat saturation pulse sequences. All were also examined with T1-weighted MR imaging after intraarticular injection of dilute gadopentetate dimeglumine and with double-contrast CT arthrography. Each imaging technique was evaluated independently by two observers, who reached a consensus interpretation. The signal characteristics of cartilage on MR images and contour abnormalities noted with all imaging techniques were evaluated and graded according to a modification of the classification of Shahriaree. Twenty-six of the 54 facets examined had chondromalacia shown by arthroscopy, which was used as the standard of reference. The sensitivity, specificity, and accuracy of each imaging technique in the diagnosis of each stage of chondromalacia patellae were determined and compared by using the McNemar two-tailed analysis. Arthroscopy showed that 28 facets were normal. Grade 1 chondromalacia patellae was diagnosed only with MR and CT arthrography in two (29%) of seven facets. Intermediate (grade 2 or 3) chondromalacia patellae was detected in two (13%) of 15 facets with T1-weighted and SPGR MR imaging, in three (20%) of 15 facets with proton density-weighted MR imaging, in seven (47%) of 15 facets with T2-weighted MR imaging, in 11 (73%) of 15 facets with CT arthrography, and in 12 (80%) of 15 facets with MR arthrography. Grade 4 was detected in three (75%) of four facets with T1-, proton

Long-range ordering of III-V semiconductor nanostructures by shallowly buried dislocation networks

International Nuclear Information System (INIS)

Coelho, J; Patriarche, G; Glas, F; Saint-Girons, G; Sagnes, I

2004-01-01

We account for lateral orderings of III-V nanostructures resulting from a GaAs/InAs/InGaAs/GaAs sequence grown on GaAs by metallorganic vapour phase epitaxy at two different temperatures. For both samples, the ordering is induced by the stress field of a periodic dislocation network (DN) shallowly buried and parallel to the surface. This DN is a grain boundary (GB) that forms, between a thin GaAs layer (on which growth was performed) and a GaAs substrate joined together by wafer bonding, in order to accommodate a tilt and a twist between these two crystals; both these misorientations are imposed in a controlled manner. This GB is composed of a one-dimensional network of mixed dislocations and of a one-dimensional network of screw dislocations. For both samples, the nanostructures observed by transmission electron microscopy (TEM) and atomic force microscopy are ordered by the underlying DN observed by TEM since they have same dimensions and orientations as the cells of the DN

Contribution to the study of screw dislocations; Contribution a l'etude des dislocations helicoidales

Energy Technology Data Exchange (ETDEWEB)

Grilhe, J [Commissariat a l' Energie Atomique, Fontenay aux Roses (France). Centre d' Etudes Nucleaires

1965-03-01

The aim of this work is to study the germination, growth and properties of screw dislocations. In the introduction (first chapter), we describe briefly the main experimental results obtained by various authors (observations of screws by Amelinckx and Bontinck in ionic crystals, by Dash in silicon crystals and by Thomas and Whelan in aluminium based alloys). We then make a few considerations concerning characteristic geometry of screws and the various methods used for calculating the energy of a dislocation. In the second chapter we study the problems involving only slip of the screw around its cylinder. We calculate the equilibrium step as a function of the forces acting on the extremities. We determine the critical stress required to disrupt the screw and study the interactions between the screw and other dislocations of the lattice. In the third chapter we consider the problem of the stability when the dislocation can climb by absorption or emission of vacancies. We study separately the stability of the size which only involves volume diffusion and the stability of the shape which depends only on the rearrangement of the vacancies along the dislocation. In chapter four we put forward a germination model for the screws: since the vacancies are not absorbed by the screw dislocations, they form clusters which take up a spiral form. The formation of these spirals is studied from the geometrical point of view in face-centered cubic systems. In chapter five we make use of the results obtained in chapters two and three for studying the growth of the spirals. (author) [French] Le but de ce travail est d'etudier la germination, la croissance et les proprietes des dislocations helico ales. Dans l'introduction (premier chapitre), nous exposons brievement les principaux resultats experimentaux obtenus par differents auteurs (observations d'helice par Amelinckx et Bontinck dans les cristaux ioniques, par Dash dans des cristaux de silicium et par Thomas et Whelan dans des

Life-history trait of the Mediterranean keystone species Patella rustica: growth and microbial bioerosion

Directory of Open Access Journals (Sweden)

I. PRUSINA

2015-05-01

Full Text Available The age and shell growth patterns in populations of Patella rustica of the Adriatic Sea were determined by analyzing the inner growth lines visible in shell sections. Marginal increment analysis showed annual periodicity with annual growth line being deposited in May. The growth analysis of 120 individual shells showed that 90.8 % of collected individuals were less than 4 years of age and only two individuals (1.6 % were older than 6 years. Population structure was described and the generalized von Bertalanffy growth parameters were calculated: asymptotic length (L∞ was 38.22 mm and the growth constant (K was 0.30 year-1. Growth performance index value of P. rustica (Ø’ was 2.64 and is among the lowest ranges reported for limpet species. Patella rustica shells were degraded to different degrees by microbial bioerosion. Microboring organisms identified were pseudofilamentous and filamentous cyanobacteria Hormathonema paulocellulare, Hyella caespitosa, Mastigocoleus testarum and Leptolyngbya sp. The overall intensity of infestation was relatively low, but increased in severity with shell length. The damage was most often restricted to the oldest parts of the shell, i.e. apex of the shell, posing difficulties in determining the exact position of the first growth line. The present study is first to introduce the use of inner growth lines in Patella rustica shell sections as a reliable method for age determination and it provides the first insight into the growth patterns of this keystone species while taking the interference of microbial shell bioerosion in consideration.

MRI evaluation of the patellar articular cartilage in patients with subluxation of the patella

International Nuclear Information System (INIS)

Nakanishi, Katsuyuki; Inoue, Masahiro; Harada, Koushi; Murakami, Takamichi; Kim, Shougen; Fujita, Norihiko; Sakurai, Kousuke; Kozuka, Takahiro

1991-01-01

In patients with subluxation of the patella, injury of the patellar articular cartilage is frequently observed and correct evaluation is important to manage these patients. We examined 11 patients with subluxation of the patella and five normal volunteers. In 12 patellofemoral joints of seven patients with subluxation of the patella, the abnormalities observed on MRI were compared with those on arthroscopy and/or at operation. MRI was performed with a Magnetom 1.5 T (Siemens) using the round surface coil. Pulse sequences were SE (TR 400 ms/TE 19 ms), FLASH(TR 320 ms/TE 15 ms FA 90deg and 40deg), and SE (TR 2000 ms/TE 26, 70 ms). We analysed MR findings of the 12 abnormal joints and 10 normal joints according to the following classification of abnormalities observed on arthroscopy; normal appearance (n=3 joints), softening and fibrillation (n=6), fragmentation (n=3), and erosion to bone (n=0). In only one of the six cases with softening and fibrillation observed on arthroscopy, MRI could visualize the thickening of patellar articular cartilage, but in all three cases with fragmentation observed on arthroscopy, MRI could visualize the thin inhomogeneous cartilage with irregular surface. The combination of SE (TR 400 ms/TE 19 ms) and FLASH (TR 320 ms/TE 15 ms FA 90deg) are extremely effective pulse sequence to detect the abnormalities of patellar articular cartilage. We conclude that MRI is a useful noninvasive method of detecting advanced changes in patellar articular cartilage. (author)

MRI evaluation of the patellar articular cartilage in patients with subluxation of the patella

Energy Technology Data Exchange (ETDEWEB)

Nakanishi, Katsuyuki; Inoue, Masahiro; Harada, Koushi; Murakami, Takamichi; Kim, Shougen; Fujita, Norihiko; Sakurai, Kousuke; Kozuka, Takahiro (Osaka Univ. (Japan). Faculty of Medicine)

1991-04-01

In patients with subluxation of the patella, injury of the patellar articular cartilage is frequently observed and correct evaluation is important to manage these patients. We examined 11 patients with subluxation of the patella and five normal volunteers. In 12 patellofemoral joints of seven patients with subluxation of the patella, the abnormalities observed on MRI were compared with those on arthroscopy and/or at operation. MRI was performed with a Magnetom 1.5 T (Siemens) using the round surface coil. Pulse sequences were SE (TR 400 ms/TE 19 ms), FLASH(TR 320 ms/TE 15 ms FA 90deg and 40deg), and SE (TR 2000 ms/TE 26, 70 ms). We analysed MR findings of the 12 abnormal joints and 10 normal joints according to the following classification of abnormalities observed on arthroscopy; normal appearance (n=3 joints), softening and fibrillation (n=6), fragmentation (n=3), and erosion to bone (n=0). In only one of the six cases with softening and fibrillation observed on arthroscopy, MRI could visualize the thickening of patellar articular cartilage, but in all three cases with fragmentation observed on arthroscopy, MRI could visualize the thin inhomogeneous cartilage with irregular surface. The combination of SE (TR 400 ms/TE 19 ms) and FLASH (TR 320 ms/TE 15 ms FA 90deg) are extremely effective pulse sequence to detect the abnormalities of patellar articular cartilage. We conclude that MRI is a useful noninvasive method of detecting advanced changes in patellar articular cartilage. (author).

Atomistic simulation of hydrogen dynamics near dislocations in vanadium hydrides

International Nuclear Information System (INIS)

Ogawa, Hiroshi

2015-01-01

Highlights: • Hydrogen–dislocation interaction was simulated by molecular dynamics method. • Different distribution of H atoms were observed at edge and screw dislocation. • Planner distribution of hydrogen may be caused by partialized edge dislocation. • Hydrogen diffusivity was reduced in both edge and screw dislocation models. • Pipe diffusion was observed for edge dislocation but not for screw dislocation. - Abstract: Kinetics of interstitial hydrogen atoms near dislocation cores were analyzed by atomistic simulation. Classical molecular dynamics method was applied to model structures of edge and screw dislocations in α-phase vanadium hydride. Simulation showed that hydrogen atoms aggregate near dislocation cores. The spatial distribution of hydrogen has a planner shape at edge dislocation due to dislocation partialization, and a cylindrical shape at screw dislocation. Simulated self-diffusion coefficients of hydrogen atoms in dislocation models were a half- to one-order lower than that of dislocation-free model. Arrhenius plot of self-diffusivity showed slightly different activation energies for edge and screw dislocations. Directional dependency of hydrogen diffusion near dislocation showed high and low diffusivity along edge and screw dislocation lines, respectively, hence so called ‘pipe diffusion’ possibly occur at edge dislocation but does not at screw dislocation

Dislocation evolution and properties enhancement of GH2036 by laser shock processing: Dislocation dynamics simulation and experiment

Energy Technology Data Exchange (ETDEWEB)

Ren, X.D., E-mail: renxd@mail.ujs.edu.cn [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Zhou, W.F.; Ren, Y.P.; Xu, S.D.; Liu, F.F. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yuan, S.Q. [Research Center of Fluid Machinery Engineering and Technical, Jiangsu University, Zhenjiang 212013 (China); Ren, N.F.; Huang, J.J. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China)

2016-01-27

This paper systematically investigated the effect of laser shock processing (LSP) on dislocation evolution and microstructure configuration of GH2036 alloy. Surface topography and roughness were tested by Axio CSM 700 microscope. The dislocation configurations were characterized by transmission electron microscope (TEM) and simulated by multi-scale discrete dislocation dynamics (DD) method. The results have confirmed that LSP had a beneficial effect on micro-hardness, which could be increased by 16%, and the surface topography exhibited excellent stability even after thermal cycle. The dislocation density and stress–strain response have strong dependence on laser power intensity. Reasonable agreement between DD simulation and experiments is achieved. The results showed that complex random microstructures can be observed in the shocked surface. The grain refinement mechanism of LSP GH2036 involves dislocation segmentation and twin intersections.

The effect of length scale on the determination of geometrically necessary dislocations via EBSD continuum dislocation microscopy

Energy Technology Data Exchange (ETDEWEB)

Ruggles, T.J., E-mail: timmyruggs@gmail.com [National Institute of Aerospace, 100 Exploration Way, Hampton, VA 23666 (United States); Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602 (United States); Rampton, T.M. [EDAX Inc., 91 McKee Drive, Mahwah, NJ 07430 (United States); Khosravani, A. [Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Fullwood, D.T. [Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602 (United States)

2016-05-15

Electron backscatter diffraction (EBSD) dislocation microscopy is an important, emerging field in metals characterization. Currently, calculation of geometrically necessary dislocation (GND) density is problematic because it has been shown to depend on the step size of the EBSD scan used to investigate the sample. This paper models the change in calculated GND density as a function of step size statistically. The model provides selection criteria for EBSD step size as well as an estimate of the total dislocation content. Evaluation of a heterogeneously deformed tantalum specimen is used to asses the method. - Highlights: • The GND to SSD transition with increasing step size is analytically modeled. • Dislocation density of a microindented tantalum single crystal is measured. • Guidelines for step size selection in EBSD dislocation microscopy are presented.

GaN microrod sidewall epitaxial lateral overgrowth on a close-packed microrod template

Science.gov (United States)

Duan, Xiaoling; Zhang, Jincheng; Xiao, Ming; Zhang, Jinfeng; Hao, Yue

2018-05-01

We demonstrate a GaN growth method using microrod sidewall epitaxial lateral overgrowth (MSELO) on a close-packed microrod template by a nonlithographic technique. The density and distribution of threading dislocations were determined by the density and distribution of microrods and the nucleation model. MSELO exhibited two different nucleation models determined by the direction and degree of substrate misorientation and the sidewall curvature: one-sidewall and three-sidewall nucleation, predicting the dislocation density values. As a result, the threading dislocation density was markedly decreased from 2 × 109 to 5 × 107 cm‑2 with a small coalescence thickness of ∼2 µm for the close-packed 3000 nm microrod sample.

Atraumatic Anterior Dislocation of the Hip Joint

Directory of Open Access Journals (Sweden)

Tadahiko Ohtsuru

2015-01-01

Full Text Available Dislocation of the hip joint in adults is usually caused by high-energy trauma such as road traffic accidents or falls from heights. Posterior dislocation is observed in most cases. However, atraumatic anterior dislocation of the hip joint is extremely rare. We present a case of atraumatic anterior dislocation of the hip joint that was induced by an activity of daily living. The possible causes of this dislocation were anterior capsule insufficiency due to developmental dysplasia of the hip, posterior pelvic tilt following thoracolumbar kyphosis due to vertebral fracture, and acetabular anterior coverage changes by postural factor. Acetabular anterior coverage changes in the sagittal plane were measured using a tomosynthesis imaging system. This system was useful for elucidation of the dislocation mechanism in the present case.

Riemann–Cartan Geometry of Nonlinear Dislocation Mechanics

KAUST Repository

Yavari, Arash

2012-03-09

We present a geometric theory of nonlinear solids with distributed dislocations. In this theory the material manifold-where the body is stress free-is a Weitzenböck manifold, that is, a manifold with a flat affine connection with torsion but vanishing non-metricity. Torsion of the material manifold is identified with the dislocation density tensor of nonlinear dislocation mechanics. Using Cartan\\'s moving frames we construct the material manifold for several examples of bodies with distributed dislocations. We also present non-trivial examples of zero-stress dislocation distributions. More importantly, in this geometric framework we are able to calculate the residual stress fields, assuming that the nonlinear elastic body is incompressible. We derive the governing equations of nonlinear dislocation mechanics covariantly using balance of energy and its covariance. © 2012 Springer-Verlag.

Results of Patello-Tibial Cerclage Wire Technique for Comminuted Patella Fractures Treated with Partial Patellectomy

Directory of Open Access Journals (Sweden)

Ender Alagöz

2014-12-01

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.

Internal stresses, dislocation mobility and ductility

Science.gov (United States)

Saada, G.

1991-06-01

The description of plastic deformation must take into account individual mechanisms and heterogeneity of plastic strain. Influence of dislocation interaction with forest dislocations and of cross slip are connected with the organization of dipole walls. The latter are described and their development is explained as a consequence of edge effects. Applications are discussed. La description de la déformation plastique doit prendre en compte les interactions individuelles des dislocations et l'hétérogénéité à grande échelle de la déformation plastique. Les interactions des dislocations mobiles avec la forêt de dislocations, le glissement dévié, ont pour effet la création de parois dipolaires. Celles-ci sont décrites et leur développement est appliqué à partir des effets de bord.

Unreduced elbow dislocation treated by Ilizarov method: A case report

Directory of Open Access Journals (Sweden)

Jovanović Vesna

2010-01-01

Full Text Available Introduction. Unreduced elbow dislocation is every elbow dislocation older than one week. It may be treated non-operatively (with prereduction traction or surgically. The treatment goals are: to reduce pain, to establish joint stability and movements. There are a lot of techniques described in literature, series are relatively small, mostly case reports. Multicentric studies have not been done. That is why there are no precisely defined therapeutic protocols. Every contribution in the field is valuable. Case Outline. A 43-year-old patient was admitted for the treatment of a three-month old unreduced elbow dislocation. Treatment has been done by Ilizarov method, using the reduction mechanism. The reduction process lasted two weeks. The Ilizarov device was removed two months after the operation, then physical therapy was started. Normal anatomical and functional findings were established five months following the operation. Conclusion. The presented method of treatment has been found as very useful, having in mind that it may solve two problems: difficult reduction and redislocation. Reduction may be done without the joint opening, step by step; retention of the reduced joint may be easily done. Physical therapy may be started without Ilizarov device removal, movements of flexion and extension may be improved without any lateral instability. There is no iatrogenic intraarticular damage, so there are no secondary joint degeneration, pains and invalidity.

[Cause analysis and management of severe dislocated or subluxated intraocular lenses in the capsular bag].

Science.gov (United States)

Wang, Wen-qing; Jia, Li-Li; Lu, Bin; Fang, Jian; Chen, Ying

2006-05-01

To analyze the causes of severe dislocated and subluxated intraocular lenses (IOL) in capsular bag and the relevancy with abnormal capsular constitution. The abnormality of capsular and the position of IOL were retrospectively analyzed by slit lamp and microscope in dilated pupil. Surgeries were performed in all of 31 cases in order to exchange or reposit the dislocated or subluxated lOL. Among 31 cases, there were 20 cases with the dislocated or subluxated IOL in the earlier postoperative period and 11 cases in the later postoperative period. The subluxated IOL in 5 cases (16.1%) were caused by the large rupture of the posterior capsular, and by the rupture of the posterior capsular in 9 cases (29.0%). A upward subluxated IOL developed in one case (3.2%) as the result of small rupture in the equater capsular. The subluxatd IOL in the anterior chamber in two cases (6.5%) was induced by the radial rupture of residual anterior capsular. The size of the IOLs in 2 cases were not matched to the diameter of the capsule bag. The dislocated IOL into the vitreous in 2 cases was caused by the rupture of the superior capsular. The subluxated IOL in 2 cases (6.5%) was caused by the zonal finers rupture due to trauma. The severe disfiguration of the IOL haptic was found in one case. The dislocated IOL in 6 cases (19.4%) was caused by asymmetric capsular shrinkage. A subluxated IOL in one case was resulted from the zonular defects with pseudoexfoliation syndrome. The postoperative corrected visual acuity was 0.5 - 1.0 in 24 eyes, 0.1 - 0.4 in 6 eyes, and 0.05 in one eye. There are several causes for the dislocated or subluxated IOL. The correction of the IOL position should depend on the cause for the dislocated or subluxated IOL.

[Patellar instability : diagnosis and treatment].

Science.gov (United States)

Ngo, Trieu Hoai Nam; Martin, Robin

2017-12-13

The aim of this paper is to present recent advances in surgical management of patellar instability. Several anatomical factors were reported to promote instability. We propose to classify them in two groups. Extra articular factors are valgus and torsion deformity. Articular factors include trochlea and patella dysplasia, tibial tubercle lateralization and medial patellofemoral ligament (MPFL) insufficiency. Acute patellar dislocations are treated conservatively, with exception for osteochondral and MPFL avulsion fractures that require acute reinsertion. Surgery is considered for recurrent instability. As we aim for a correction of all contributing elements, we prefer a two stages approach. Extra articular factors are treated first by osteotomy, followed by articular factors after 4-6 months. This allows separate rehabilitation protocols.

Imaging of patellofemoral instability

International Nuclear Information System (INIS)

Waldt, S.; Rummeny, E.J.

2012-01-01

Patellofemoral instability remains a diagnostic and therapeutic challenge due to its multifactorial genesis. The purpose of imaging is to systematically analyze predisposing factors, such as trochlear dysplasia, patella alta, tibial tuberosity-trochlear groove (TT-TG) distance, rotational deformities of the lower limb and patellar tilt. In order to evaluate anatomical abnormalities with a sufficient diagnostic accuracy, standardized measurement methods and implementation of various imaging modalities are necessary. Diagnosis of acute and often overlooked lateral patellar dislocation can be established with magnetic resonance imaging (MRI) because of its characteristic patterns of injury. Damage to the medial patellofemoral ligament (MPFL) has a significance just as high as the predisposing risk factors in relation to the cause of chronic instability. (orig.) [de

Statistics of dislocation pinning at localized obstacles

Energy Technology Data Exchange (ETDEWEB)

Dutta, A. [S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700098 (India); Bhattacharya, M., E-mail: mishreyee@vecc.gov.in; Barat, P. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata 700064 (India)

2014-10-14

Pinning of dislocations at nanosized obstacles like precipitates, voids, and bubbles is a crucial mechanism in the context of phenomena like hardening and creep. The interaction between such an obstacle and a dislocation is often studied at fundamental level by means of analytical tools, atomistic simulations, and finite element methods. Nevertheless, the information extracted from such studies cannot be utilized to its maximum extent on account of insufficient information about the underlying statistics of this process comprising a large number of dislocations and obstacles in a system. Here, we propose a new statistical approach, where the statistics of pinning of dislocations by idealized spherical obstacles is explored by taking into account the generalized size-distribution of the obstacles along with the dislocation density within a three-dimensional framework. Starting with a minimal set of material parameters, the framework employs the method of geometrical statistics with a few simple assumptions compatible with the real physical scenario. The application of this approach, in combination with the knowledge of fundamental dislocation-obstacle interactions, has successfully been demonstrated for dislocation pinning at nanovoids in neutron irradiated type 316-stainless steel in regard to the non-conservative motion of dislocations. An interesting phenomenon of transition from rare pinning to multiple pinning regimes with increasing irradiation temperature is revealed.

Ultrasonic Study of Dislocation Dynamics in Lithium -

Science.gov (United States)

Han, Myeong-Deok

1987-09-01

Experimental studies of dislocation dynamics in LiF single crystals, using ultrasonic techniques combined with dynamic loading, were performed to investigate the time evolution of the plastic deformation process under a short stress pulse at room temperature, and the temperature dependence of the dislocation damping mechanism in the temperature range 25 - 300(DEGREES)K. From the former, the time dependence of the ultrasonic attenuation was understood as resulting from dislocation multiplication followed by the evolution of mobile dislocations to immobile ones under large stress. From the latter, the temperature dependence of the ultrasonic attenuation was interpreted as due to the motion of the dislocation loops overcoming the periodic Peierls potential barrier in a manner analogous to the motion of a thermalized sine-Gordon chain under a small stress. The Peierls stress obtained from the experimental results by application of Seeger's relaxation model with exponential dislocation length distribution was 4.26MPa, which is consistent with the lowest stress for the linear relation between the dislocation velocity and stress observed by Flinn and Tinder.

An experimental study of dislocation loop nucleation

International Nuclear Information System (INIS)

Bounaud, J.Y.; Leteurtre, J.

1975-01-01

The nucleation of dislocation loops is experimentally studied by observing the demixion of the Burgers vectors of dislocation loops nucleated in copper whiskers irradiated in flexion by fission fragments at room temperature. The demixion of Burgers vectors is observed by the dimensional effects of dislocation loops: after irradiation, the applied stress is removed; the whisker shows a residual strain that is due to loops because, after an annealing treatment to evaporate dislocation loops, each whisker recovers its initial straight shape. Everywhere along the whisker, the radius of curvature is measured and plotted vs the max. applied stress. Estimations of the interstitial and vacancy dislocation loop nuclei are derived [fr

Representation of dislocation cores using Nye tensor distributions

International Nuclear Information System (INIS)

Hartley, Craig S.; Mishin, Y.

2005-01-01

This paper demonstrates how the cores of atomistically simulated dislocations in Cu and Al can be represented by a distribution of infinitesimal dislocations described by appropriate components of the Nye tensor. Components calculated from atomic positions in the dislocated crystal are displayed as contour plots on the plane normal to the dislocation line. The method provides an accurate and instructive means for characterizing dislocation core structures and calculating the total Burgers vector

Nail patella syndrome: a rare cause of renal failure in a young adult ...

African Journals Online (AJOL)

Nail Patella Syndrome (NPS) is a rare hereditary disease affecting multiple systems with predominant involvement of Kidney, Bones and Nails and Eyes. We report a case of NPS which presented as renal failure in a 22 year old male. The patient was admitted with decreased urine output and features of fluid overload and ...

Structure of the Dislocation in Sapphire

DEFF Research Database (Denmark)

Bilde-Sørensen, Jørgen; Thölen, A. R.; Gooch, D. J.

1976-01-01

Experimental evidence of the existence of 01 0 dislocations in the {2 0} prism planes in sapphire has been obtained by transmission electron microscopy. By the weak-beam technique it has been shown that the 01 0 dislocations may dissociate into three partials. The partials all have a Burgers vector...... of ⅓ 01 0 and are separated by two identical faults. The distance between two partials is in the range 75-135 Å, corresponding to a fault energy of 320±60 mJ/m2. Perfect 01 0 dislocations have also been observed. These dislocations exhibited either one or two peaks when imaged in the (03 0) reflection...

Dislocation of jaws

International Nuclear Information System (INIS)

Katzberg, R.W.; Hayakawa, K.; Anderson, Q.N.; Manzione, J.V.; Helms, C.A.; Tallents, R.

1984-01-01

Pluri-directional tomographic and arthrotomographic findings are described in six patients with dislocation of the jaw severe enough to require medical assistance. A grooved defect along the posterior aspect of the condylar head was noted in two of the six patients. The arthrotomographic findings that were obtained in one patient that was dislocated at the time of the arthrogram did not suggest a meniscocondyle incoordination as a mechanism. However, arthrotomographic findings in the six reported cases suggest that significant intra-articular soft tissue damage may result. (orig.)

Results of Operative and Nonoperative Treatment of Rockwood Types III and V Acromioclavicular Joint Dislocation

Science.gov (United States)

Joukainen, Antti; Kröger, Heikki; Niemitukia, Lea; Mäkelä, E. Antero; Väätäinen, Urho

2014-01-01

Background: The optimal treatment of acute, complete dislocation of the acromioclavicular joint (ACJ) is still unresolved. Purpose: To determine the difference between operative and nonoperative treatment in acute Rockwood types III and V ACJ dislocation. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: In the operative treatment group, the ACJ was reduced and fixed with 2 transarticular Kirschner wires and ACJ ligament suturing. The Kirschner wires were extracted after 6 weeks. Nonoperatively treated patients received a reduction splint for 4 weeks. At the 18- to 20-year follow-up, the Constant, University of California at Los Angeles Shoulder Rating Scale (UCLA), Larsen, and Simple Shoulder Test (SST) scores were obtained, and clinical and radiographic examinations of both shoulders were performed. Results: Twenty-five of 35 potential patients were examined at the 18- to 20-year follow-up. There were 11 patients with Rockwood type III and 14 with type V dislocations. Delayed surgical treatment for ACJ was used in 2 patients during follow-up: 1 in the operatively treated group and 1 in the nonoperatively treated group. Clinically, ACJs were statistically significantly less prominent or unstable in the operative group than in the nonoperative group (normal/prominent/unstable: 9/4/3 and 0/6/3, respectively; P = .02) and in the operative type III (P = .03) but not type V dislocation groups. In operatively and nonoperatively treated patients, the mean Constant scores were 83 and 85, UCLA scores 25 and 27, Larsen scores 11 and 11, and SST scores 11 and 12 at follow-up, respectively. There were no statistically significant differences in type III and type V dislocations. In the radiographic analysis, the ACJ was wider in the nonoperative than the operative group (8.3 vs 3.4 mm; P = .004), and in the type V dislocations (nonoperative vs operative: 8.5 vs 2.4 mm; P = .007). There was no statistically significant difference between study groups in

Smectic meniscus and dislocations

International Nuclear Information System (INIS)

Geminard, J.C.; Oswald, P.; Holyst, R.

1998-01-01

In ordinary liquids the size of a meniscus and its shape is set by a competition between surface tension and gravity. The thermodynamical process of its creation can be reversible. On the contrary, in smectic liquid crystals the formation of the meniscus is always an irreversible thermodynamic process since it involves the creation of dislocations (therefore it involves friction). Also the meniscus is usually small in experiments with smectics in comparison to the capillary length and therefore the gravity does not play any role in determining the meniscus shape. Here we discuss the relation between dislocations and meniscus in smectics. The theoretical predictions are supported by a recent experiment performed on freely suspended films of smectic liquid crystals. In this experiment the measurement of the meniscus radius of curvature gives the pressure difference, Δp, according to the Laplace law. From the measurements of the growth dynamics of a dislocation loop (governed by Δp) we find the line tension (∼8 x 10 -8 dyn) and the mobility of an elementary edge dislocation (∼4 x 10 - 7 cm 2 s/g). (author)

Dynamic aspects of dislocation motion: atomistic simulations

International Nuclear Information System (INIS)

Bitzek, Erik; Gumbsch, Peter

2005-01-01

Atomistic simulations of accelerating edge and screw dislocations were carried out to study the dynamics of dislocations in a face centered cubic metal. Using two different embedded atom potentials for nickel and a simple slab geometry, the Peierls stress, the effective mass, the line tension and the drag coefficient were determined. A dislocation intersecting an array of voids is used to study dynamic effects in dislocation-obstacle interactions. A pronounced effect caused by inertial overshooting is found. A dynamic line tension model is developed which reproduces the simulation results. The model can be used to easily estimate the magnitude of inertial effects in the interaction of dislocations with localized obstacles for different obstacle strengths, -spacings and temperatures

The relationship between chondromalacia patella, medial meniscal tear and medial periarticular bursitis in patients with osteoarthritis

Directory of Open Access Journals (Sweden)

Resorlu Mustafa

2017-11-01

Full Text Available This study investigated the presence of bursitis in the medial compartment of the knee (pes anserine, semimembranosus-tibial collateral ligament, and medial collateral ligament bursa in osteoarthritis, chondromalacia patella and medial meniscal tears.

Evaluation of medial patellofemoral ligament tears after acute lateral patellar dislocation: comparison of high-frequency ultrasound and MR

Energy Technology Data Exchange (ETDEWEB)

Zhang, Guang-Ying; Ding, Hong-Yu [Shandong University, Department of Ultrasonography, Qianfoshan Hospital, Jinan (China); Zheng, Lei; Sun, Bai-Sheng [Chinese People' s Armed Police Force, Department of Radiology, Shandong Provincial Corps Hospital, Jinan (China); Li, En-Miao [Jinan Third People' s Hospital, Department of Ultrasonography, Jinan (China); Shi, Hao [Shandong University, Department of Radiology, Qianfoshan Hospital, Jinan (China)

2015-01-15

The purpose of this study was to compare the diagnostic performance of high-frequency ultrasound with MR in the evaluation of medial patellofemoral ligament (MPFL) lesions after acute lateral patellar dislocation (LPD). High-frequency ultrasound and MR images were prospectively obtained in 97 consecutive patients with acute LPD. Images were acquired using standardised protocols and were independently evaluated by two radiologists. The MPFL was assessed at three sites (patellar insertion, femoral attachment, and mid-substance) for signs of injury. Of a total of 291 sites in 97 MPFLs, 127 showed proven MPFL tear at surgery, including 51 sites of complete tear and 76 sites of partial tear. In a site-based analysis, the sensitivity, specificity, and accuracy of high-frequency ultrasound was 90.8 %, 96.3 %, and 94.6 %, respectively, for partial MPFL tear and 86.3 %, 96.3 %, and 94 %, respectively, for complete tear. For MR, the sensitivity, specificity, and accuracy was 81.6 %, 95.7 %, and 91.3 %, respectively, for partial MPFL tear and 80.4 %, 95.7 %, and 92.1 %, respectively, for complete tear. There was no statistical difference between high-frequency ultrasound and MR in the assessment of partial (P = 0.1, 0.777, 0.155) or complete (P = 0.425, 0.777, 0.449) MPFL lesions. Interobserver agreement was very good for high-frequency ultrasound and good for MR. Data suggest that high-frequency ultrasound and MR have similar diagnostic performance in the evaluation of MPFL lesions after acute LPD. (orig.)

Evaluation of medial patellofemoral ligament tears after acute lateral patellar dislocation: comparison of high-frequency ultrasound and MR

International Nuclear Information System (INIS)

Zhang, Guang-Ying; Ding, Hong-Yu; Zheng, Lei; Sun, Bai-Sheng; Li, En-Miao; Shi, Hao

2015-01-01

The purpose of this study was to compare the diagnostic performance of high-frequency ultrasound with MR in the evaluation of medial patellofemoral ligament (MPFL) lesions after acute lateral patellar dislocation (LPD). High-frequency ultrasound and MR images were prospectively obtained in 97 consecutive patients with acute LPD. Images were acquired using standardised protocols and were independently evaluated by two radiologists. The MPFL was assessed at three sites (patellar insertion, femoral attachment, and mid-substance) for signs of injury. Of a total of 291 sites in 97 MPFLs, 127 showed proven MPFL tear at surgery, including 51 sites of complete tear and 76 sites of partial tear. In a site-based analysis, the sensitivity, specificity, and accuracy of high-frequency ultrasound was 90.8 %, 96.3 %, and 94.6 %, respectively, for partial MPFL tear and 86.3 %, 96.3 %, and 94 %, respectively, for complete tear. For MR, the sensitivity, specificity, and accuracy was 81.6 %, 95.7 %, and 91.3 %, respectively, for partial MPFL tear and 80.4 %, 95.7 %, and 92.1 %, respectively, for complete tear. There was no statistical difference between high-frequency ultrasound and MR in the assessment of partial (P = 0.1, 0.777, 0.155) or complete (P = 0.425, 0.777, 0.449) MPFL lesions. Interobserver agreement was very good for high-frequency ultrasound and good for MR. Data suggest that high-frequency ultrasound and MR have similar diagnostic performance in the evaluation of MPFL lesions after acute LPD. (orig.)

Nature of Dislocations in Silicon

DEFF Research Database (Denmark)

Hansen, Lars Bruno; Stokbro, Kurt; Lundqvist, Bengt

1995-01-01

Interaction between two partial 90 degrees edge dislocations is studied with atomic-scale simulations using the effective-medium tight-binding method. A large separation between the two dislocations (up to 30 Angstrom), comparable to experimental values, is achieved with a solution of the tight-b...

Intraocular lens dislocation after whole-body vibration.

Science.gov (United States)

Vela, José I; Andreu, David; Díaz-Cascajosa, Jesús; Buil, José A

2010-10-01

We present 2 cases of intraocular lens (IOL) dislocation that appeared shortly after the patients exercised on a vibration platform. The first patient was a 71-year-old woman who presented with lens subluxation in her right eye and a complete posterior IOL dislocation in her left eye. The second case was a 62-year-old woman who presented with unilateral IOL dislocation within the capsular bag in her right eye. Timing from IOL implantation to dislocation was approximately 6 years and 4 years, respectively. Pars plana vitrectomy with removal of the dislocated IOL was performed in both patients. Whole-body vibration training has become increasingly popular as a form of exercise training. It reportedly may provide benefits in physical function and in some diseases, especially in older people. However, evidence-based protocols ensuring safety and efficacy in this population are lacking. We discuss vibration as a cause of late IOL dislocation. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

EXTRA-ARTICULAR FRACTURE OF THE MEDIAL END OF THE CLAVICLE ASSOCIATED WITH TYPE IV ACROMIOCLAVICULAR DISLOCATION: CAAE REPORT.

Science.gov (United States)

Correa, Mário Chaves; Gonçalves, Lucas Braga Jacques; Vilela, Jose Carlos Souza; Leonel, Igor Lima; Costa, Lincoln Paiva; de Andrade, Ronaldo Percopi

2011-01-01

Fractures of the clavicle and acromioclavicular dislocations are very common injuries when they occur separately. The combination of an acromioclavicular dislocation and a fracture of the lateral third of the clavicle is not rare. However, there are very few reported cases of acromioclavicular dislocations associated with fractures of the middle third of the clavicle; those associated with fractures of the medial third are even rarer. We report the case of an adult male who suffered an acromioclavicular dislocation (type IV) associated with a displaced extra-articular fracture of the medial end of the clavicle (Almann group 3) in a cycling accident. The patient was treated during the acute phase with open reduction and internal fixation of the two lesions. At the clinical evaluation 12 months after the surgery, the patient was asymptomatic, with full active and passive mobility, and normal strength and endurance of the shoulder girdle. Radiographs and a three-dimensional CT scan showed persistent posterosuperior subluxation of the acromioclavicular joint and anatomical consolidation of the clavicular fracture.

Treatment of mandibular symphyseal fracture combined with dislocated intracapsular condylar fractures.

Science.gov (United States)

Xu, Xiaofeng; Shi, Jun; Xu, Bing; Dai, Jiewen; Zhang, Shilei

2015-03-01

To evaluate the treatment methods of mandibular symphyseal fracture combined with dislocated intracapsular condylar fractures (MSF&DICF) and to compare the effect of different treatment methods of condylar fractures. Twenty-eight patients with MSF&DICF were included in this study. Twenty-two sites were treated by open reduction, and all the medial condylar fragments were fixed with titanium screws; whereas the other 22 sites underwent close treatment. The surgical effect between these 2 groups was compared based on clinical examination and radiographic examination results. Seventeen of 22 condyle fractures were repositioned in the surgery group, whereas 4 of 22 condyle fractures were repositioned in the close treatment group. Statistical difference was observed between these 2 groups (P condyle fractures should be treated by surgical reduction with the maintenance of the attachment of lateral pterygoid muscle, which is beneficial to repositioning the dislocated condyle to its original physiological position, to closure of the mandibular lingual gap, to restore the mandibular width.

Dislocations and other topological oddities

Science.gov (United States)

Pieranski, Pawel

2016-03-01

We will show that the book Dislocations by Jacques Friedel, published half a century ago, can still be recommended, in agreement with the author's intention, as a textbook ;for research students at University and for students at engineering schools as well as for research engineers;. Indeed, today dislocations are known to occur not only in solid crystals but also in many other systems discovered more recently such as colloidal crystals or liquid crystals having periodic structures. Moreover, the concept of dislocations is an excellent starting point for lectures on topological defects occurring in systems equipped with order parameters resulting from broken symmetries: disclinations in nematic or hexatic liquid crystals, dispirations in chiral smectics or disorientations in lyotropic liquid crystals. The discussion of dislocations in Blue Phases will give us an opportunity to call on mind Sir Charles Frank, friend of Jacques Friedel since his Bristol years, who called these ephemeral mesophases ;topological oddities;. Being made of networks of disclinations, Blue Phases are similar to Twist Grain Boundary (TGB) smectic phases, which are made of networks of screw dislocations and whose existence was predicted by de Gennes in 1972 on the basis of the analogy between smectics and superconductors. We will stress that the book by Jacques Friedel contains seeds of this analogy.

Dislocations

Science.gov (United States)

... Fitness Diseases & Conditions Infections Drugs & Alcohol School & Jobs Sports Expert Answers (Q&A) Staying Safe Videos for Educators Search English Español First Aid: ... bones become separated. Dislocations are caused by falls and hard impacts, such as in sports injuries, and are more common in teens than ...

Dislocation dynamics in Al-Li alloys: mean jump distance and activation length of moving dislocations

International Nuclear Information System (INIS)

De Hosson, J.Th.M.; Huis Int Veld, A.

1984-01-01

It is pointed out that aluminum-lithium based alloys offer considerable promise for structural applications, especially in the aerospace industry. This promise is related to the potential for high strength in combination with a density which is lower than that found in conventional aluminum alloys. In addition, the modulus of elasticity is higher than corresponding values in conventional aluminum alloys. A nuclear magnetic resonance study of the mechanism of dislocation motion in Al-2.2 wt pct Li is reported. Information about the effective mean jump distance of mobile dislocations is provided by in situ nuclear spin relaxation measurements. The activation length of mobile dislocations has been obtained from strain-rate change experiments on Al-2.2 wt pct Li. The considered study shows that pulsed nuclear magnetic resonance is a complementary new technique for the study of moving dislocations in Al-Li alloys. 28 references

Formation of dislocation dipoles in irradiated graphite

International Nuclear Information System (INIS)

Niwase, Keisuke

2005-01-01

Recently, we have proposed a dislocation dipole accumulation model to explain the irradiation-induced amorphization of graphite. However, the structure of dislocation dipole in the hexagonal networks is still an open question at the atomic-level. In this paper, we propose a possible formation process of the dislocation dipole

Recovery after fracture dislocation of L3/L4 ASIA B: Case report

Directory of Open Access Journals (Sweden)

Gustavo Caldera

2016-02-01

Full Text Available In fracture dislocations of the lumbar region, two anatomical facts can help preserve neurological damage in patients, when compared with trauma in the cervical or thoracic region. Firstly, the spinal cord in adults extends only to the lower edge of the first lumbar vertebra, and secondly, the large vertebral space in this region gives ample space for the roots of the cauda equine. As a result, the nerve injury may be minimal, because the nerve roots in this region are accommodated in a larger area, with less content and space. This study presents the case of a 48-year-old male, a construction worker, who suffered a fall from a height of approximately 15 meters, directly hitting the lumbar region against a beam, and presenting pain and inability to move the legs. The patient was brought to the emergency room 1 hour after the accident, clinically assessed, submitted to x-rays and a CT scan, and diagnosed as having an ASIA B L3-L4 fracture dislocation. Three hours after the accident, reduction was performed via posterior transpedicular fixation. One week later, an anterior approach was performed. The patient progressed to ASIA C 24 hours after the first surgery. Three months later, the patient was functional with ASIA D and good sphincter control. The author's purpose is to show the results obtained by an intervention in the initial hours of the trauma, which helped promote the evolution from a nonfunctional injury to a functional one, with near-total recovery. Keywords: Spine fracture, Recovery, Neurological deficit, Asia scale, Dislocation

Imaging findings of anterior hip dislocations

Energy Technology Data Exchange (ETDEWEB)

Pfeifer, Kyle [Mallinckrodt Institute of Radiology, Department of Radiology, St. Louis, MO (United States); Leslie, Michael [Yale School of Medicine, Department of Orthopedics and Rehabilitation, New Haven, CT (United States); Menn, Kirsten; Haims, Andrew [Yale University School of Medicine, Department of Radiology and Biomedical Imaging, New Haven, CT (United States)

2017-06-15

Anterior hip dislocations are rare orthopedic emergencies resulting from high-energy trauma and have unique imaging characteristics on radiography, computed tomography (CT), and magnetic resonance imaging (MRI). Imaging findings on CT and MRI allow for the prompt recognition and classification of anterior hip dislocations, which guides patient management and reduces complications. The purpose of this article is to review imaging findings of anterior hip dislocations, specifically focusing on CT and MRI. (orig.)

High dislocation density of tin induced by electric current

International Nuclear Information System (INIS)

Liao, Yi-Han; Liang, Chien-Lung; Lin, Kwang-Lung; Wu, Albert T.

2015-01-01

A dislocation density of as high as 10 17 /m 2 in a tin strip, as revealed by high resolution transmission electron microscope, was induced by current stressing at 6.5 x 10 3 A/ cm 2 . The dislocations exist in terms of dislocation line, dislocation loop, and dislocation aggregates. Electron Backscattered Diffraction images reflect that the high dislocation density induced the formation of low deflection angle subgrains, high deflection angle Widmanstätten grains, and recrystallization. The recrystallization gave rise to grain refining

High-temperature discrete dislocation plasticity

Science.gov (United States)

Keralavarma, S. M.; Benzerga, A. A.

2015-09-01

A framework for solving problems of dislocation-mediated plasticity coupled with point-defect diffusion is presented. The dislocations are modeled as line singularities embedded in a linear elastic medium while the point defects are represented by a concentration field as in continuum diffusion theory. Plastic flow arises due to the collective motion of a large number of dislocations. Both conservative (glide) and nonconservative (diffusion-mediated climb) motions are accounted for. Time scale separation is contingent upon the existence of quasi-equilibrium dislocation configurations. A variational principle is used to derive the coupled governing equations for point-defect diffusion and dislocation climb. Superposition is used to obtain the mechanical fields in terms of the infinite-medium discrete dislocation fields and an image field that enforces the boundary conditions while the point-defect concentration is obtained by solving the stress-dependent diffusion equations on the same finite-element grid. Core-level boundary conditions for the concentration field are avoided by invoking an approximate, yet robust kinetic law. Aspects of the formulation are general but its implementation in a simple plane strain model enables the modeling of high-temperature phenomena such as creep, recovery and relaxation in crystalline materials. With emphasis laid on lattice vacancies, the creep response of planar single crystals in simple tension emerges as a natural outcome in the simulations. A large number of boundary-value problem solutions are obtained which depict transitions from diffusional to power-law creep, in keeping with long-standing phenomenological theories of creep. In addition, some unique experimental aspects of creep in small scale specimens are also reproduced in the simulations.

Comparison of axial T1 spin-echo and T1 fat-saturation magnetic resonance imaging techniques in the diagnosis of chondromalacia patellae.

Science.gov (United States)

Vanarthos, W J; Pope, T L; Monu, J U

1994-12-01

To test the diagnostic value of T1 spin-echo and T1 fat-saturated magnetic resonance images (MRIs), we reviewed axial T1-weighted images with and without fat saturation in 20 patients with clinically suspected chondromalacia of the patella. All scans were obtained on 1.5-MR units. The scans were randomly ordered and reviewed independently at different times by two radiologists without knowledge of the arthroscopy results. The sensitivity of the individual techniques for detecting grade 3 or 4 chondromalacia patellae was 92% for fat-saturated axial T1-weighted images alone, and 67% for axial T1-weighted images without fat saturation. The sensitivity of the combined techniques was 100% for grades 3 and 4 and 90% for all grades (0 to 4). Chondromalacia patellae is diagnosed more accurately by using T1 fat saturation than by using T1 spin-echo images. With a combination of the two techniques, accuracy is 90% to 100%.

Electrical conduction along dislocations in plastically deformed GaN

Energy Technology Data Exchange (ETDEWEB)

Kamimura, Y; Yokoyama, T; Oiwa, H; Edagawa, K [Institute of Industrial Science, the University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505 (Japan); Yonenaga, I, E-mail: yasushi@iis.u-tokyo.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan)

2009-07-15

Electrical conduction along dislocations in plastically deformed n-GaN single crystals has been investigated by scanning spread resistance microscopy (SSRM). In the SSRM images, many conductive spots have been observed, which correspond to electrical conduction along the dislocations introduced by deformation. Here, the introduced dislocations are b=(a/3)<1overline 210> edge dislocations parallel to the [0001] direction. The current values at the spots normalized to the background current value are larger than 100. Previous works have shown that grown-in edge dislocations in GaN are nonconductive. The high conductivity of the deformation-introduced edge dislocations in the present work suggests that the conductivity depends sensitively on the dislocation core structure.

Rare Inferior Shoulder Dislocation (Luxatio Erecta)

OpenAIRE

Cift, Hakan; Soylemez, Salih; Demiroglu, Murat; Ozkan, Korhan; Ozden, Vahit Emre; Ozkut, Afsar T.

2015-01-01

Although shoulder dislocations have been seen very frequently, inferior dislocation of shoulder constitutes only 0.5% of all shoulder dislocations. We share our 4 patients with luxatio erecta and present their last clinical control. 2 male and 2 female Caucasian patients were diagnosed as luxatio erecta. Patients’ ages were 78, 62, 65, and 76. All patients’ reduction was done by traction-abduction and contour traction maneuver in the operating room. The patients had no symptoms and no limitat...

Volar dislocation of the index carpometacarpal joint in association with a Bennett's fracture of the thumb: a rare injury pattern.

LENUS (Irish Health Repository)

Dillon, J P

2012-02-03

We describe a case of volar dislocation of the index carpometacarpal (CMC) joint in association with a Bennett\\'s fracture of the thumb following a motorcycle accident. Volar dislocation of the index carpometacarpal joint is an exceedingly rare but easily missed injury, with only a few reported cases in the literature. This report highlights the importance of a true lateral radiograph and close scrutiny of the film to detect this injury. Closed reduction supplemented with Kirschner wire fixation restored normal anatomical relations and achieved an excellent clinical result.

The epidemiology of shoulder dislocations in Oslo.

Science.gov (United States)

Liavaag, S; Svenningsen, S; Reikerås, O; Enger, M; Fjalestad, T; Pripp, A H; Brox, J I

2011-12-01

There are few previous studies on the incidence of shoulder dislocation in the general population. The aim of the study was to report the incidence of acute shoulder dislocations in the capital of Norway (Oslo) in 2009. Patients of all ages living in Oslo, sustaining a dislocation of the glenohumeral joint, were identified using electronic diagnosis registers, patient protocols, radiological registers of the hospitals, and the Norwegian Patient Register (NPR). The overall incidence rate was 56.3 [95% confidence interval (CI) 50.2-62.4] per 100,000 person-years, with rates of 82.2 (95% CI 71.7-92.8) and 30.9 (95% CI 24.5-37.3) in men and women, respectively. The incidence of primary dislocations was 26.2 (95% CI 22.1-30.4). The overall incidence of shoulder dislocations in Oslo was higher than previously reported incidences. The incidence of primary dislocations was also higher than that in previously reported studies for the general population but it was close to the incidence reported in Malmø, Sweden. © 2011 John Wiley & Sons A/S.

Atomistically-informed dislocation dynamics in FCC crystals

International Nuclear Information System (INIS)

Martinez, E.; Marian, J.; Arsenlis, A.; Victoria, M.; Martinez, E.; Victoria, M.; Perlado, J.M.

2008-01-01

Full text of publication follows. We will present a nodal dislocation dynamics (DD) model to simulate plastic processes in fcc crystals. The model explicitly accounts for all slip systems and Burgers vectors observed in fcc systems, including stacking faults and partial dislocations. We derive simple conservation rules that describe all partial dislocation interactions rigorously and allow us to model and quantify cross-slip processes, the structure and strength of dislocation junctions, and the formation of fcc-specific structures such as stacking fault tetrahedra. The DD framework is built upon isotropic non-singular linear elasticity, and supports itself on information transmitted from the atomistic scale. In this fashion, connection between the meso and micro scales is attained self-consistently with core parameters fitted to atomistic data. We perform a series of targeted simulations to demonstrate the capabilities of the model, including dislocation reactions and dissociations and dislocation junction strength. Additionally we map the four-dimensional stress space relevant for cross-slip and relate our fundings to the plastic behaviour of' monocrystalline fcc metals. (authors)

Creep Deformation by Dislocation Movement in Waspaloy.

Science.gov (United States)

Whittaker, Mark; Harrison, Will; Deen, Christopher; Rae, Cathie; Williams, Steve

2017-01-12

Creep tests of the polycrystalline nickel alloy Waspaloy have been conducted at Swansea University, for varying stress conditions at 700 °C. Investigation through use of Transmission Electron Microscopy at Cambridge University has examined the dislocation networks formed under these conditions, with particular attention paid to comparing tests performed above and below the yield stress. This paper highlights how the dislocation structures vary throughout creep and proposes a dislocation mechanism theory for creep in Waspaloy. Activation energies are calculated through approaches developed in the use of the recently formulated Wilshire Equations, and are found to differ above and below the yield stress. Low activation energies are found to be related to dislocation interaction with γ' precipitates below the yield stress. However, significantly increased dislocation densities at stresses above yield cause an increase in the activation energy values as forest hardening becomes the primary mechanism controlling dislocation movement. It is proposed that the activation energy change is related to the stress increment provided by work hardening, as can be observed from Ti, Ni and steel results.

Dislocation Dynamics in Al-Li Alloys. Mean Jump Distance and Activation Length of Moving Dislocations

NARCIS (Netherlands)

Hosson, J.Th.M. De; Huis in 't Veld, A.; Tamler, H.; Kanert, O.

1984-01-01

Pulsed nuclear magnetic resonance proved to be a complementary new technique for the study of moving dislocations in Al-Li alloys. The NMR technique, in combination with transmission electron microscopy and strain-rate change experiments have been applied to study dislocation motion in Al-2.2 wt% Li

Isolated Post-Traumatic Radial Head Dislocation, A Rare and Easily Missed Injury-A Case Report

Directory of Open Access Journals (Sweden)

V Gupta

2013-03-01

Full Text Available Dislocation of the head of the radius may be either congenital, an isolated injury or more commonly part of a complex injury to the elbow such as the Monteggia fracturedislocation. Isolated traumatic radial head dislocation without associated injuries in children is a rare and easily missed condition. We report such a case in a 7-year-old boy without any associated injuries or co-morbid conditions. Initially the diagnosis was missed, and 6 weeks later open reduction was performed with annular ligament reconstruction surgery. At the one-year follow up, the patient had returned to most normal activities, showing only slight terminal restriction of pronation. We discuss the injury mechanism and management for the Monteggia fracturedislocation and review the available literature.

[Histomorphological analyse of accelerating the fibrocartilage layer repair of patella-patellar tendon junction in rabbits by low intensity pulsed ultrasound stimulation].

Science.gov (United States)

Zhang, Baoliang; Lü, Hongbin; Hu, Jianzhong; Xu, Daqi; Zhou, Jingyong; Wang, Ye

2013-08-01

To analyse the effect of low intensity pulsed ultrasound stimulation (LIPUS) on accelerating the fibrocartilage layer repair of patella-patellar tendon junction. A total of 60 mature female New Zealand white rabbits undergoing standard partial patellectomy were divided into 2 groups randomly. The control group was given comfort treatment and the treatment group was given LIPUS treatment starting from day 3 to the end of week 6 postoperatively. The scheduled time points of animal euthanization would be at week 6, week 12 and week 18 postoperatively. The patella-patellar tendon (PPT) complex would be harvested and cut into sections after decalcification for H&E staining, Safranine o/fast green staining. The thickness and gray value of fibrocartilage layer were analyzed by SANO Microscope Partner image analyzer. At week 6, week 12 and week 18 postoperatively, the fibrocartilage layer in the treatment group was significantly thicker than that in the control group (Pfibrocartilage layer was significantly smaller than that in the control group (Pfibrocartilage layer repair of patella-patellar tendon junction in rabbit models.

Influence of mobile dislocations on phase separation in binary alloys

International Nuclear Information System (INIS)

Haataja, Mikko; Leonard, Francois

2004-01-01

We introduce a continuum model to describe the phase separation of a binary alloy in the presence of mobile dislocations. The kinetics of the local composition and dislocation density are coupled through their elastic fields. We show both analytically and numerically that mobile dislocations modify the standard spinodal decomposition process, and lead to several regimes of growth. Depending on the dislocation mobility and observation time, the phase separation may be accelerated, decelerated, or unaffected by mobile dislocations. For any finite dislocation mobility, we show that the domain growth rate asymptotically becomes independent of the dislocation mobility, and is faster than the dislocation-free growth rate

A BIOMECHANICAL STUDY OF LATERAL RELEASE AND ELMSLIE-TRILLAT PROCEDURES TO RESTABILISETHE MALTRACKTNG PATELLA

Directory of Open Access Journals (Sweden)

MM. Tahmasbi

1999-09-01

Full Text Available  The resistant* of pateSa against lateral displacement (Le. the stability, was studied tinder a range of conditions in vitro, at a range of knee flexion angles. Muscle forces were applied in physiological directions along the separate quadriceps muscles. Normal muscle actions with constant tension showed constant patellar stability up to sixty degrees knee flexion, and then a significant increase at ninety degrees. A pathological knee was simulated by relaxing vastus medians, and ■ lateral stability then dropped by 47%. Isolated rttlnaeular release in the pathological knee did not improve stability significantly towards normal, while 6mm tibial tubercle medlaEsatum restored stabtBty by 52% towards normal, except neat JuM extension. Combined release phis tubercle medtafisathm. restored stability 59% towards normal In knee flexion, and 23% up to ten degrees flexion.

Evaluation of the Chondromalacia Patella Using a Microscopy Coil: Comparison of the Two-Dimensional Fast Spin Echo Techniques and the Three-Dimensional Fast Field Echo Techniques

International Nuclear Information System (INIS)

Kim, Hyun Joo; Lee, Sang Hoon; Kang, Chang Ho; Ryu, Jeong Ah; Shin, Myung Jin; Cho, Kyung Ja; Cho, Woo Shin

2011-01-01

We wanted to compare the two-dimensional (2D) fast spin echo (FSE) techniques and the three-dimensional (3D) fast field echo techniques for the evaluation of the chondromalacia patella using a microscopy coil. Twenty five patients who underwent total knee arthroplasty were included in this study. Preoperative MRI evaluation of the patella was performed using a microscopy coil (47 mm). The proton density-weighted fast spin echo images (PD), the fat-suppressed PD images (FS-PD), the intermediate weighted-fat suppressed fast spin echo images (iw-FS-FSE), the 3D balanced-fast fi eld echo images (B-FFE), the 3D water selective cartilage scan (WATS-c) and the 3D water selective fluid scan (WATS-f) were obtained on a 1.5T MRI scanner. The patellar cartilage was evaluated in nine areas: the superior, middle and the inferior portions that were subdivided into the medial, central and lateral facets in a total of 215 areas. Employing the Noyes grading system, the MRI grade 0-I, II and III lesions were compared using the gross and microscopic findings. The sensitivity, specificity and accuracy were evaluated for each sequence. The significance of the differences for the individual sequences was calculated using the McNemar test. The gross and microscopic findings demonstrated 167 grade 0-I lesions, 40 grade II lesions and eight grade III lesions. Iw-FS-FSE had the highest accuracy (sensitivity/specificity/accuracy = 88%/98%/96%), followed by FSPD (78%/98%/93%, respectively), PD (76%/98%/93%, respectively), B-FFE (71%/100%/93%, respectively), WATS-c (67%/100%/92%, respectively) and WATS-f (58%/99%/89%, respectively). There were statistically significant differences for the iw-FS-FSE and WATS-f and for the PD-FS and WATS-f (p < 0.01). The iw-FS-FSE images obtained with a microscopy coil show best diagnostic performance among the 2D and 3D GRE images for evaluating the chondromalacia patella

Evaluation of the Chondromalacia Patella Using a Microscopy Coil: Comparison of the Two-Dimensional Fast Spin Echo Techniques and the Three-Dimensional Fast Field Echo Techniques

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyun Joo; Lee, Sang Hoon; Kang, Chang Ho; Ryu, Jeong Ah; Shin, Myung Jin; Cho, Kyung Ja; Cho, Woo Shin [University of Ulsan College of Medicine, Asan Medical Center, Seoul (Korea, Republic of)

2011-02-15

We wanted to compare the two-dimensional (2D) fast spin echo (FSE) techniques and the three-dimensional (3D) fast field echo techniques for the evaluation of the chondromalacia patella using a microscopy coil. Twenty five patients who underwent total knee arthroplasty were included in this study. Preoperative MRI evaluation of the patella was performed using a microscopy coil (47 mm). The proton density-weighted fast spin echo images (PD), the fat-suppressed PD images (FS-PD), the intermediate weighted-fat suppressed fast spin echo images (iw-FS-FSE), the 3D balanced-fast fi eld echo images (B-FFE), the 3D water selective cartilage scan (WATS-c) and the 3D water selective fluid scan (WATS-f) were obtained on a 1.5T MRI scanner. The patellar cartilage was evaluated in nine areas: the superior, middle and the inferior portions that were subdivided into the medial, central and lateral facets in a total of 215 areas. Employing the Noyes grading system, the MRI grade 0-I, II and III lesions were compared using the gross and microscopic findings. The sensitivity, specificity and accuracy were evaluated for each sequence. The significance of the differences for the individual sequences was calculated using the McNemar test. The gross and microscopic findings demonstrated 167 grade 0-I lesions, 40 grade II lesions and eight grade III lesions. Iw-FS-FSE had the highest accuracy (sensitivity/specificity/accuracy = 88%/98%/96%), followed by FSPD (78%/98%/93%, respectively), PD (76%/98%/93%, respectively), B-FFE (71%/100%/93%, respectively), WATS-c (67%/100%/92%, respectively) and WATS-f (58%/99%/89%, respectively). There were statistically significant differences for the iw-FS-FSE and WATS-f and for the PD-FS and WATS-f (p < 0.01). The iw-FS-FSE images obtained with a microscopy coil show best diagnostic performance among the 2D and 3D GRE images for evaluating the chondromalacia patella

Evaluation of the relationship between T1ρ and T2 values and patella cartilage degeneration in patients of the same age group.

Science.gov (United States)

Nishioka, Hiroaki; Hirose, Jun; Okamoto, Nobukazu; Okada, Tatsuya; Oka, Kiyoshi; Taniwaki, Takuya; Nakamura, Eiichi; Yamashita, Yasuyuki; Mizuta, Hiroshi

2015-03-01

The aim of this study was to investigate the association between the T1ρ and T2 values and the progression of cartilage degeneration in patients of the same age group. Sagittal T1ρ and T2 mapping and three-dimensional (3D) gradient-echo images were obtained from 78 subjects with medial knee osteoarthritis (OA). The degree of patella cartilage degeneration was classified into four groups using MRI-based grading: apparently normal cartilage, mild OA, moderate OA, and severe OA group. We measured the T1ρ and T2 values (ms) in the regions of interest set on the full-thickness patella cartilage. Then, we analyzed the relationship between the T1ρ and T2 values and the degree of patella cartilage degeneration. There were no significant differences in age among the four groups. Both the T1ρ and T2 values showed a positive correlation with the degree of OA progression (ρ=0.737 and ρ=0.632, respectively). By comparison between the apparently normal cartilage and the mild OA groups, there were significant differences in the T1ρ mapping, but not in the T2 mapping. Our study confirmed that T1ρ and T2 mapping can quantitatively evaluate the degree of patella cartilage degeneration in patients within the same age group. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Dislocation Interactions in Olivine Revealed by HR-EBSD

Science.gov (United States)

Wallis, David; Hansen, Lars N.; Britton, T. Ben; Wilkinson, Angus J.

2017-10-01

Interactions between dislocations potentially provide a control on strain rates produced by dislocation motion during creep of rocks at high temperatures. However, it has been difficult to establish the dominant types of interactions and their influence on the rheological properties of creeping rocks due to a lack of suitable observational techniques. We apply high-angular resolution electron backscatter diffraction to map geometrically necessary dislocation (GND) density, elastic strain, and residual stress in experimentally deformed single crystals of olivine. Short-range interactions are revealed by cross correlation of GND density maps. Spatial correlations between dislocation types indicate that noncollinear interactions may impede motion of proximal dislocations at temperatures of 1000°C and 1200°C. Long-range interactions are revealed by autocorrelation of GND density maps. These analyses reveal periodic variations in GND density and sign, with characteristic length scales on the order of 1-10 μm. These structures are spatially associated with variations in elastic strain and residual stress on the order of 10-3 and 100 MPa, respectively. Therefore, short-range interactions generate local accumulations of dislocations, leading to heterogeneous internal stress fields that influence dislocation motion over longer length scales. The impacts of these short- and/or long-range interactions on dislocation velocities may therefore influence the strain rate of the bulk material and are an important consideration for future models of dislocation-mediated deformation mechanisms in olivine. Establishing the types and impacts of dislocation interactions that occur across a range of laboratory and natural deformation conditions will help to establish the reliability of extrapolating laboratory-derived flow laws to real Earth conditions.

Diagnosis of chondromalacia patellae using CT arthrography

Energy Technology Data Exchange (ETDEWEB)

Reiser, M.; Karpf, P.M.; Bernett, P.

1982-08-01

Using anatomical specimens for experimental investigations, the physical-technical prerequisites for proper demonstration of the femoro-patellar articulation were determined and the following results obtained: hyaline cartilage possesses an attenuation value of 25-35 HU; artificial lesions from 1 mm. deep and 2 mm. wide minimum can be visualized; the use of positive contrast medium is best suited for demonstration of chondral lesions. In clinical practice we found that the various stages of cartilaginous degeneration peculiar to chondromalacia (Fruend I to III) are clearly demonstrated by CT arthrography. In CT the predisposing changes in the morphology of the patella and the femoro-patellar articulation are more precisely defined than in conventional tangential roentgenograms. In 69 cases the CT arthrographic findings could be verified at operation. However, the extent and severity of the lesions was, at times, underestimated.

Low energy dislocation structures due to unidirectional deformation at low temperatures

DEFF Research Database (Denmark)

Hansen, Niels; Kuhlmann-Wilsdorf, D.

1986-01-01

The line energy of dislocations is {Gb2f(v)/4π} 1n(R/b) with R range of the dislocation stress field from the axis. This equation implies that quasi-uniform distributions are unstable relative to dislocation clusters in which neighboring dislocations mutually screen their stress fields, correspon......The line energy of dislocations is {Gb2f(v)/4π} 1n(R/b) with R range of the dislocation stress field from the axis. This equation implies that quasi-uniform distributions are unstable relative to dislocation clusters in which neighboring dislocations mutually screen their stress fields......, correspondingly leaving the major fraction of the volume free of dislocations. The value of R decreases in the following order: pile-ups to dipolar mats, Taylor lattices, tilt and dipolar walls to dislocation cell structures. This is the same order in which dislocation structures tend to develop with increasing...... dislocation density and hence increased dislocation interactions, leading to the corresponding energy decrease per unit length of dislocation line. Taking into consideration also the longer-range “termination stresses” of finite dislocation boundaries, and minimizing the total energy, explains the size...

Electron-dislocation interaction at low temperatures. Progress report

International Nuclear Information System (INIS)

1976-01-01

Studies of the interaction of mobile dislocations with electrons have shown that dislocation motion can be, in part, described by treating the dislocation as an underdamped oscillator. In particular, studies in lead alloys have shown tht dislocation motion can be considered as the motion of string, slightly damped by electrons, without regard for any other lattice friction. In addition we have shown that silver solutes, in lead crystals, occupy, partially, interstitial sites. Finally, we have shown that dislocations in copper interact, unexpectedly, with electrons. This is shown by measuring the influence of a magnetic field on the flow stress of copper crystals at 4.2 0 K

Structural and in vivo mechanical characterization of canine patellar cartilage: a closed chondromalacia patellae model.

Science.gov (United States)

LaBerge, M; Audet, J; Drouin, G; Rivard, C H

1993-01-01

The purpose of this project was to study the relationship between the structure of the patellar cartilage and its response to static compressive loading with a closed chondromalacia patellae model. An animal model was used to induce degeneration of the patella that was monitored quantitatively and qualitatively as a function of time. Ten adult mongrel dogs had their left patellofemoral groove replaced by a customized metallic implant covered with a thin film of polyethylene for periods of 3 months (five dogs) and 6 months (five dogs). An indenter was designed to perform mechanical indentation testing on the patellar cartilage in situ. The animals were anesthetized and the response of patellar cartilage to a static compressive load of 4.5 MPa was monitored for 20 min and its relaxation after load removal for 20 min. Indentation tests were performed every 3 months of the implantation period. At the end of the implantation period, the patellae were processed for histology, and sections were stained with Safranin-O indicative of the proteoglycans content. Macroscopically, no apparent degeneration or fibrillation of the patellar surfaces was observed after 3 or 6 months of implantation. However, the patellar surface showed a change in coloration after 6 months. A 17 +/- 3% and 37 +/- 8% deformation of the cartilage were calculated for the 3-month and 6-month specimens, respectively. Histologically, a progressive loss of proteoglycans was observed in the matrix as a function of implantation time. These results indicated that an increase in cartilage compliance is associated with an intrinsic remodeling of the cartilage matrix and that these changes might occur without external signs of degeneration and can be quantified.

Generalized dynamics of moving dislocations in quasicrystals

International Nuclear Information System (INIS)

Agiasofitou, Eleni; Lazar, Markus; Kirchner, Helmut

2010-01-01

A theoretical framework for dislocation dynamics in quasicrystals is provided according to the continuum theory of dislocations. Firstly, we present the fundamental theory for moving dislocations in quasicrystals giving the dislocation density tensors and introducing the dislocation current tensors for the phonon and phason fields, including the Bianchi identities. Next, we give the equations of motion for the incompatible elastodynamics as well as for the incompatible elasto-hydrodynamics of quasicrystals. We continue with the derivation of the balance law of pseudomomentum thereby obtaining the generalized forms of the Eshelby stress tensor, the pseudomomentum vector, the dynamical Peach-Koehler force density and the Cherepanov force density for quasicrystals. The form of the dynamical Peach-Koehler force for a straight dislocation is obtained as well. Moreover, we deduce the balance law of energy that gives rise to the generalized forms of the field intensity vector and the elastic power density of quasicrystals. The above balance laws are produced for both models. The differences between the two models and their consequences are revealed. The influences of the phason fields as well as of the dynamical terms are also discussed.

Irreducible Traumatic Posterior Shoulder Dislocation

Directory of Open Access Journals (Sweden)

Blake Collier

2017-01-01

Full Text Available History of present illness: A 22-year-old male presented to the Emergency Department complaining of right shoulder pain after a motocross accident. He was traveling at approximately 10 mph around a turn when he lost control and was thrown over the handlebars, landing directly on his right shoulder. On arrival, he was holding his arm in adduction and internal rotation. An area of swelling was noted over his anterior shoulder. He was unable to abduct his shoulder. No humeral gapping was noted. He had normal neuro-vascular status distal to the injury. Significant findings: Radiographs demonstrated posterior displacement of the humeral head on the “Y” view (see white arrow and widening of the glenohumeral joint space on anterior-posterior view (see red arrow. The findings were consistent with posterior dislocation and a Hill-Sachs type deformity. Sedation was performed and reduction was attempted using external rotation, traction counter-traction. An immediate “pop” was felt during the procedure. Post-procedure radiographs revealed a persistent posterior subluxation with interlocking at posterior glenoid. CT revealed posterior dislocation with acute depressed impaction deformity medial to the biceps groove with the humeral head perched on the posterior glenoid, interlocked at reverse Hill-Sachs deformity (see blue arrow. Discussion: Posterior shoulder dislocations are rare and represent only 2% of all shoulder dislocations. Posterior shoulder dislocations are missed on initial diagnosis in more than 60% of cases.1 Posterior shoulder dislocations result from axial loading of the adducted and internally rotated shoulder, violent muscle contractions (resulting from seizures or electrocution, a direct posterior force applied to the anterior shoulder.1 Physical findings include decreased anterior prominence of the humeral head, increased palpable posterior prominence of the humeral head below the acromion, increased palpable prominence of the

Molecular dynamics simulation of dislocations in uranium dioxide

Energy Technology Data Exchange (ETDEWEB)

Fossati, Paul [CEA, DEN, DPC, SCCME, F-91191 Gif-sur-Yvette Cedex (France); Van Brutzel, Laurent, E-mail: laurent.vanbrutzel@cea.fr [CEA, DEN, DPC, SCCME, F-91191 Gif-sur-Yvette Cedex (France); Devincre, Benoît [LEM, CNRS-ONERA, 29 avenue de la Division Leclerc, F-92322 Châtillon Cedex (France)

2013-11-15

The plasticity of the fluorite structure in UO{sub 2} is investigated with molecular dynamics simulation and empirical potential. The stacking fault energies and the dislocation core structures with Burgers vector a/2 〈110〉 are systematically calculated. All dislocation core structures show a significant increase of the oxygen sub-lattice disorder at temperatures higher than 1500 K. The threshold stress for dislocation glide is found to decrease with increasing temperature but its values is always very high, several GPa at 0 K and several hundred of MPa at 2000 K. A relation between the dislocation mobility dependence with temperature and the increase of the oxygen sub-lattice disorder in the dislocation cores is established.

Metastablity of the undissociated state of dissociated dislocations

International Nuclear Information System (INIS)

Takeuchi, Shin

2005-01-01

Undissociated, metastable dislocations have been observed in various crystals in addition to stable dissociated dislocations by high-resolution transmission electron microscopy. The origin of the metastablity of the undissociated state has been discussed specifically for the dissociation into Shockley partial dislocations in fcc or hcp lattice. It is shown that the metastability is due either to a high Peierls-Nabarro stress larger than a few percent of the shear modulus of the partial dislocations and/or to the increase of the total core energy by an increase of the dangling bonds. The metastablity of undissociated dislocations in zincblende III-V compounds is concluded to be due to a contribution of the latter effect

Comparison of Tension-Band Wiring With the Cable Pin System in Patella Fractures: A Randomized Prospective Study.

Science.gov (United States)

Tian, Qing-xian; Hai, Yong; Du, Xin-ru; Xu, Zi-yu; Lu, Tie; Shan, Lei; Liu, Yang; Zhou, Jun-lin

2015-12-01

To compare the outcome of tension-band wiring (TBW) with the cable pin system (CPS) for transverse fractures of the patella. Randomized prospective study. Academic Level I trauma center. From February 2008 to December 2011, 73 consecutive patients with transverse fractures of the patella were prospectively enrolled in this study. The patients were randomly divided into 2 groups: one group was treated using the CPS, and the other group was treated using the modified TBW. The clinical outcome assessment included analyses of the radiographic images, the modified Hospital for Special Surgery scoring system, and complications. The follow-up time ranged from 12 to 29 months. All fractures healed, with a union rate of 100%. The fracture healing time was significantly shorter in the CPS group (8.51 ± 2.59 weeks, n = 34) compared with the TBW group (11.79 ± 3.04 weeks, n = 39). Postoperative complications in the CPS and TBW groups were observed in 1 and 9 patients, respectively, a difference that was statistically significant. The mean Hospital for Special Surgery score for the CPS group (90.53 ± 5.19 points) was significantly higher than that for the TBW group (81.36 ± 12.71 points). The CPS is a viable option for transverse fractures of the patella and is associated with a shorter healing time, fewer complications, and better function than TBW. Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Atomic-scale dislocation dynamics in radiation damage environment

International Nuclear Information System (INIS)

Osetsky, Y.; Stoller, R.; Bacon, D.J.

2007-01-01

Full text of publication follows: The dynamics behavior of dislocations determines mechanical properties of crystalline materials. Long-range interactions between a moving dislocation and other defects can be treated within a continuum approach via interaction of their stress and strain fields. However, a vast contribution to mechanical properties depends on the direct interaction between dislocations and other defects and depends very much on the particular atomic scale structure of the both moving dislocation core and the obstacle. In this work we review recent progress in large-scale modeling of dislocation dynamics in metals at the atomic level by molecular dynamics and statics. We review the modem techniques used to simulate dynamics of dislocations in different lattice structures, the dependence on temperature, strain rate and obstacle size. Examples are given for bcc, fcc and hcp metals where edge and screw dislocations interact with vacancy (loops, voids, stacking fault tetrahedra, etc), self-interstitial clusters and secondary phase precipitates. Attention is paid to interpretation of atomistic results from the point of view of parameterization of continuum models. The latter is vitally necessary for further application in 3-dimensional dislocation dynamics within the multi-scale materials modeling approach. Research sponsored by the Division of Materials Sciences and Engineering and the Office of Fusion Energy Sciences, U.S. Department of Energy, under contract DE-AC0S-00OR22725 with UT-Battelle, LLC. (authors)

Interactions between Dislocations and Grain Boundaries

NARCIS (Netherlands)

Soer, Wouter Anthon

2006-01-01

Dislocations (line defects) and grain boundaries (planar defects) are two types of lattice defects that are crucial to the deformation behavior of metals. Permanent deformation of a crystalline material is microscopically associated with the nucleation and propagation of dislocations, and extensive

Hydrogen diffusion in the elastic fields of dislocations in iron

Energy Technology Data Exchange (ETDEWEB)

Sivak, A. B., E-mail: Sivak-AB@nrcki.ru; Sivak, P. A. [National Research Centre Kurchatov Institute (Russian Federation); Romanov, V. A.; Chernov, V. M. [National Research Tomsk State University (Russian Federation)

2016-12-15

The effect of dislocation stress fields on the sink efficiency thereof is studied for hydrogen interstitial atoms at temperatures of 293 and 600 K and at a dislocation density of 3 × 10{sup 14} m{sup –2} in bcc iron crystal. Rectilinear full screw and edge dislocations in basic slip systems 〈111〉(110), 〈111〉(112), 〈100〉(100), and 〈100〉(110) are considered. Diffusion of defects is simulated by means of the object kinetic Monte Carlo method. The energy of interaction between defects and dislocations is calculated using the anisotropic theory of elasticity. The elastic fields of dislocations result in a less than 25% change of the sink efficiency as compared to the noninteracting linear sink efficiency at a room temperature. The elastic fields of edge dislocations increase the dislocation sink efficiency, whereas the elastic fields of screw dislocations either decrease this parameter (in the case of dislocations with the Burgers vector being 1/2〈111〉) or do not affect it (in the case of dislocations with the Burgers vector being 〈100〉). At temperatures above 600 K, the dislocations affect the behavior of hydrogen in bcc iron mainly owing to a high binding energy between the hydrogen atom and dislocation cores.

Nanoscale dislocation shear loops at static equilibrium and finite temperature

Science.gov (United States)

Dang, Khanh; Capolungo, Laurent; Spearot, Douglas E.

2017-12-01

Atomistic simulations are used to determine the resolved shear stress necessary for equilibrium and the resulting geometry of nanoscale dislocation shear loops in Al. Dislocation loops with different sizes and shapes are created via superposition of elemental triangular dislocation displacement fields in the presence of an externally imposed shear stress. First, a bisection algorithm is developed to determine systematically the resolved shear stress necessary for equilibrium at 0 K. This approach allows for the identification of dislocation core structure and a correlation between dislocation loop size, shape and the computed shear stress for equilibrium. It is found, in agreement with predictions made by Scattergood and Bacon, that the equilibrium shape of a dislocation loop becomes more circular with increasing loop size. Second, the bisection algorithm is extended to study the influence of temperature on the resolved shear stress necessary for stability. An approach is presented to compute the effective lattice friction stress, including temperature dependence, for dislocation loops in Al. The temperature dependence of the effective lattice friction stress can be reliably computed for dislocation loops larger than 16.2 nm. However, for dislocation loops smaller than this threshold, the effective lattice friction stress shows a dislocation loop size dependence caused by significant overlap of the stress fields on the interior of the dislocation loops. Combined, static and finite temperature atomistic simulations provide essential data to parameterize discrete dislocation dynamics simulations.

Surgical treatment for old subaxial cervical dislocation with bilateral locked facets in a 3-year-old girl: A case report.

Science.gov (United States)

Li, Cheng; Li, Lei; Duan, Jingzhu; Zhang, Lijun; Liu, Zhenjiang

2018-05-01

This study aimed to describe the case of a 3-year-old girl with old bilateral facet dislocation on cervical vertebrae 6 and 7, who had spinal cord transection, received surgical treatment, and achieved a relative satisfactory therapeutic effect. A 3-year-old girl was urgently transferred to the hospital after a car accident. DIAGNOSES:: she was diagnosed with splenic rupture, intracranial hemorrhage, cervical dislocation, spinal transection, and Monteggia fracture of the left upper limb. The girl underwent emergency splenectomy and was transferred to the intensive care unit of the hospital 15 days later. One-stage anterior-posterior approach surgery (anterior discectomy, posterior laminectomy, and pedicle screw fixation) was performed when the patient stabilized after 45-day symptomatic treatment. The operation was uneventful. The reduction of lower cervical dislocation was satisfactory, with sufficient spinal cord decompression. The internal fixation position was good, and the spinal sequence was well restored. The girl was discharged 2 weeks later after the operation and followed up for 2 years. The major nerve function of both upper limbs was recovered, with no obvious retardation of the growth of immature spine. A satisfactory therapeutic effect was achieved for a pediatric old subaxial cervical dislocation with bilateral locked facets using anterior discectomy, posterior laminectomy, and pedicle screw fixation. The posterior pedicle screw fixation provided a good three-dimensional stability of the spine, with reduced risk and complications caused by anterior internal fixation. The growth of immature spine was not obviously affected during the 2-year follow-up.

Work softening in nanocrystalline materials induced by dislocation annihilation

DEFF Research Database (Denmark)

Ungar, Tamas; Li, Li; Tichy, Geza

2011-01-01

Cold rolling reduces the quantity of dislocation densities in Ni–18% Fe alloys prepared by electrochemical deposition. The dislocation density evolution proposed earlier for the linearly decreasing work-hardening rate during stage III is revisited. The solution of the differential equation predicts...... that when the initial dislocation density is smaller or larger than the saturation value, then the dislocation density will increase or decrease during further plastic deformation. The predictions are verified by experimental values of dislocation densities determined by X-ray line-profile analysis....

Dissociated dislocations in Ni: a computational study

International Nuclear Information System (INIS)

Szelestey, P.; Patriarca, M.; Kaski, K.

2005-01-01

A systematic computational study of the behavior of a (1/2) dissociated screw dislocation in fcc nickel is presented, in which atomic interactions are described through an embedded-atom potential. A suitable external stress is applied on the system, both for modifying the equilibrium separation distance d and moving the dislocation complex. The structure of the dislocation and its corresponding changes during the motion are studied in the framework of the two-dimensional Peierls model, for different values of the ratio d/a', where a' is the period of the Peierls potential. The distance between the edge and screw components of the partials, as well as their widths, undergo a modulation with period a', as the dislocation moves, and the amplitudes of such oscillations are shown to depend on d/a'. The stress profile acting on the dislocation complex is analyzed and the effective Peierls stress is estimated for different values of d/a'

Dislocation density changes in nickel under creep

International Nuclear Information System (INIS)

Moiseeva, I.V.; Okrainets, P.N.; Pishchak, V.K.

1984-01-01

Variation in dislocation density was studied in the process of nickel creep p at t=900 deg c and σ=2 kgf/mm 2 . The dislocation structure was studied independently by the X-ray technique and transmission electron-microscopy. The e two methods show good conformity of results by comparison. It is concluded that independent determination of dislocation density under creep is possible us sing the X-ray technique

Estudo anatômico do ligamento patelofemoral lateral em joelho de cadáveres Anatomical study of the lateral patellofemoral ligament in cadaver knees

Directory of Open Access Journals (Sweden)

Marcelo Schmidt Navarro

2008-07-01

fresh cadavers by means of anatomical dissections. The dissections were standardized and the data were noted down and forwarded to statistical analysis. RESULTS: The LPFL presented a mean 16.05 mm width (standard deviation of 2.48, 42.10 mm length (standard deviation of 8.84. The femoral insertion was found at the lateral femoral epicondyle and with a fan-like expansion of the fibers, predominantly in the posterior region proximal to the lateral epicondyle. In the patella, the insertion found was in the upper-lateral region (in the middle of the upper third of the coronal plan, also with expanded fibers, but less intensely so. In the sagittal plan, the ligament was located in the posterior half of the border of the patella. The LPFL was isolated in the second lateral retinacular layer, the deep transverse retinaculum. CONCLUSION: The LPFL is located in the deep transverse retinacular layer with the presence of a fan-like expansion of its fibers both in the femoral and in the patellar insertions. The insertion is more posterior and proximal at the femoral epicondyle and in the posterior half of the patellar border (sagittal plan and in the upper-lateral aspect.

Lack of experience is a significant factor in the missed diagnosis of perilunate fracture dislocation or isolated dislocation

Directory of Open Access Journals (Sweden)

Ilker Çolak

2018-01-01

Conclusion: The results of this study indicated that lack of experience was the most important factor in the misdiagnosis of perilunate fracture dislocation or isolated dislocation. Level of Evidence: Level IV, diagnostic study.

Gradients of geometrically necessary dislocations from white beam microdiffraction

International Nuclear Information System (INIS)

Barabash, R.I.; Ice, G.E.; Pang, J.W.L.

2005-01-01

Variations in the local crystallographic orientation due to the presence of geometrically necessary dislocations and dislocation boundaries smear the distribution of intensity near Laue reflections. Here, some simple model distributions of geometrically necessary dislocations, GNDs, are used to estimate the dislocation tensor field from the intensity distribution of Laue peaks. Streaking of the Laue spots is found to be quantitatively and qualitatively distinct depending on the ratio between the absorption coefficient and the GND density gradient. In addition, different slip systems cause distinctly different Laue-pattern streaking. Experimental Laue patterns are therefore sensitive to stored dislocations and GNDs. As an example, white beam microdiffraction was applied to characterize the dislocation arrangement in a deformed polycrystalline Ni grain during in situ uniaxial tension

Ultrasound as a probe of dislocation density in aluminum

International Nuclear Information System (INIS)

Mujica, Nicolás; Cerda, Maria Teresa; Espinoza, Rodrigo; Lisoni, Judit; Lund, Fernando

2012-01-01

Graphical abstract: Display Omitted - Abstract: Dislocations are at the heart of the plastic behavior of crystalline materials yet it is notoriously difficult to perform quantitative, non-intrusive measurements of their single or collective properties. Dislocation density is a critical variable that determines dislocation mobility, strength and ductility. On the one hand, individual dislocations can be probed in detail with transmission electron microscopy. On the other hand, their collective properties must be simulated numerically. Here we show that ultrasound technology can be used to measure dislocation density. This development rests on theory—a generalization of the Granato–Lücke theory for the interaction of elastic waves with dislocations—and resonant ultrasound spectroscopy (RUS) measurements. The chosen material is aluminum, to which different dislocation contents were induced through annealing and cold-rolling processes. The dislocation densities obtained with RUS compare favorably with those inferred from X-ray diffraction, using the modified Williamson–Hall method.

Association between patellar cartilage defects and patellofemoral geometry: a matched-pair MRI comparison of patients with and without isolated patellar cartilage defects.

Science.gov (United States)

Mehl, Julian; Feucht, Matthias J; Bode, Gerrit; Dovi-Akue, David; Südkamp, Norbert P; Niemeyer, Philipp

2016-03-01

To compare the geometry of the patellofemoral joint on magnetic resonance images (MRI) between patients with isolated cartilage defects of the patella and a gender- and age-matched control group of patients without patellar cartilage defects. A total of 43 patients (17 female, 26 male) with arthroscopically verified grade III and IV patellar cartilage defects (defect group) were compared with a matched-pair control group of patients with isolated traumatic rupture of the anterior cruciate ligament without cartilage defects of the patellofemoral joint. Preoperative MRI images were analysed retrospectively with regard to patellar geometry (width, thickness, facet angle), trochlear geometry (dysplasia according to Dejour, sulcus angle, sulcus depth, lateral condyle index, trochlea facet asymmetry, lateral trochlea inclination) and patellofemoral alignment (tibial tuberosity-trochlear groove distance, patella height, lateral patella displacement, lateral patellofemoral angle, patella tilt, congruence angle). In addition to the comparison of group values, the measured values were compared to normal values reported in the literature, and the frequency of patients with pathologic findings was compared between both groups. The defect group demonstrated a significantly higher proximal chondral sulcus angle (p patellofemoral joint. In particular, a flat and shallow trochlea, trochlea dysplasia and patella alta seem to contribute to the development of patellar cartilage defects, which must be taken into consideration when planning to do surgical cartilage repair at the patella. III.

Transition pathways in the unfaulting of dislocation loops

International Nuclear Information System (INIS)

Kubota, Alison; Wolfer, W.G.

2005-01-01

In order to study the dynamic mechanism of loop unfaulting, we performed large-scale classical molecular dynamics simulations involving computational cells with several millions of atoms. To induce dislocation loop unfaulting, we launched 1 ps duration traction stress pulses at a free surface of the computational box. In many cases, we observe unfaulting to involve both intuitive and complex dislocation processes with multiple Shockley partial dislocations. However, in some instances, we observe unfaulting to occur by a sudden instability of the stacking fault without clear traces of dislocation reactions

Hereditary onchyo-osteo-arthrodysplasia (nail-patella syndrome) with progressive renal failure

International Nuclear Information System (INIS)

Stellamor, K.; Anzboeck, W.

1989-01-01

A case of a fully developed hereditary onycho-osteo-arthrodysplasia (nail-patella syndrome) is presented. The typical signs, such as the iliac horns or variations of the knees, cubitals and nails should be familiar to every radiologist. The associated nephropathy seems to be caused by typical changes in the glomerular basement membrane seen in electron microscopy. Asymptomatic proteinuria is found in about 60% of the cases, in 5,5-8% the disease leads to the necessity of haemodialysis because of renal insufficiency. Hence, early diagnosis is very important. (orig.) [de

Palmar dislocation of scaphoid and lunate

Directory of Open Access Journals (Sweden)

Khalid Koulali Idrissi

2011-11-01

Full Text Available A palmar dislocation of scaphoid and lunate is uncommon. We have found only 19 reported cases in the literature. We reported a simultaneous, divergent dislocation. The closed reduction followed by percutaneous pinning has given a good result without avascular necrosis of any carpal bone.

Dislocation structure and cold resistance of low-carbon steel

International Nuclear Information System (INIS)

Gul', Yu.P.; Karnaukh, A.I.

1975-01-01

In the formation of the dislocation structure of a small (10%) deformation, the determining effect on the cold brittleness temperature is exerted by the degree of uniformity in the distribution of dislocations and microvolumes. The overall density of the dislocations is of secondary importance here. By pretreatment to achieve more uniform distribution and dispersion of particles of the excess phase, the degree of uniformity of dislocation distribution in microvolumes can be increased, the cold brittleness temperature lowered and the effect of various deformation patterns on resistance to cold counterbalanced. The formation of a cell-type dislocation structure in the case of a nonuniform distribution of relatively large particles of the excess phase and in that of a large overall density of dislocations does not result in low brittleness temperatures. The formation of a cell-type dislocation structure in the case of uniform distribution of particles of the excess phase and of a comparatively small overall density of dislocations is accompanied by a very pronounced decrease in cold brittleness temperature not only by comparison with other types of dislocation structure but also with the normalized state. At the same time the formation of this kind of a cell structure leads to a substantial (factor of 2-5) increase in resistance to plastic deformation. The prerequisites for obtaining an optimum dislocation are fulfilled either by a combination of hardening from the austenitic region and prompt, small-scale (5%) deformation, or by a combination of accelerated cooling from the austenitic region, 30-40% deformation and high yield. The size of the dislocation cells observed under the electron microscope does not exhibit - within the limits investigated - any direct effect on the cold brittleness temperature. (author)

Dislocation defect interaction in irradiated Cu

International Nuclear Information System (INIS)

Schaeublin, R.; Yao, Z.; Spaetig, P.; Victoria, M.

2005-01-01

Pure Cu single crystals irradiated at room temperature to low doses with 590 MeV protons have been deformed in situ in a transmission electron microscope in order to identify the basic mechanisms at the origin of hardening. Cu irradiated to 10 -4 dpa shows at room temperature a yield shear stress of 13.7 MPa to be compared to the 8.8 MPa of the unirradiated Cu. Irradiation induced damage consists at 90% of 2 nm stacking fault tetrahedra, the remaining being dislocation loops and unidentified defects. In-situ deformation reveals that dislocation-defect interaction can take several forms. Usually, dislocations pinned by defects bow out under the applied stress and escape without leaving any visible defect. From the escape angles obtained at 183 K, an average critical stress of 100 MPa is deduced. In some cases, the pinning of dislocations leads to debris that are about 20 nm long, which formation could be recorded during the in situ experiment

Prediction of dislocation boundary characteristics

DEFF Research Database (Denmark)

Winther, Grethe

Plastic deformation of both fcc and bcc metals of medium to high stacking fault energy is known to result in dislocation patterning in the form of cells and extended planar dislocation boundaries. The latter align with specific crystallographic planes, which depend on the crystallographic......) and it is found that to a large extent the dislocations screen each other’s elastic stress fields [3]. The present contribution aims at advancing the previous theoretical analysis of a boundary on a known crystallographic plane to actual prediction of this plane as well as other boundary characteristics....... Crystal plasticity calculations combined with the hypothesis that these boundaries separate domains with local differences in the slip system activity are introduced to address precise prediction of the experimentally observed boundaries. The presentation will focus on two cases from fcc metals...

Coccidiomycosis infection of the patella mimicking a neoplasm – two case reports

International Nuclear Information System (INIS)

Li, Yi-Chen; Calvert, George; Hanrahan, Christopher J; Jones, Kevin B; Randall, Robert Lor

2014-01-01

Coccidioidomycosis is an endemic fungal infection in the southwestern of United States. Most infections are asymptomatic or manifest with mild respiratory complaints. Rare cases may cause extrapulmonary or disseminated disease. We report two cases of knee involvement that presented as isolated lytic lesions of the patella mimicking neoplasms. The first case, a 27 year-old immunocompetent male had progressive left anterior knee pain for four months. The second case was a 78 year-old male had left anterior knee pain for three months. Both of them had visited general physicians without conclusive diagnosis. A low attenuation lytic lesion in the patella was demonstrated on their image studies, and the initial radiologist’s interpretation was suggestive of a primary bony neoplasm. The patients were referred for orthopaedic oncology consultation. The first case had a past episode of pulmonary coccioidomycosis 2 years prior, while the second case had no previous coccioidal infection history but lived in an endemic area, the central valley of California. Surgical biopsy was performed in both cases due to diagnostic uncertainty. Final pathologic examination revealed large thick walled spherules filled with endospores establishing the final diagnosis of extrapulmonary coccidioidomycosis. Though history and laboratory findings are supportive, definitive diagnosis still depends on growth in culture or endospores identified on histology. We suggest that orthopaedic surgeons and radiologists keep in mind that chronic fungal infections can mimic osseous neoplasm by imaging

Modeling of dislocation dynamics in germanium Czochralski growth

Science.gov (United States)

Artemyev, V. V.; Smirnov, A. D.; Kalaev, V. V.; Mamedov, V. M.; Sidko, A. P.; Podkopaev, O. I.; Kravtsova, E. D.; Shimansky, A. F.

2017-06-01

Obtaining very high-purity germanium crystals with low dislocation density is a practically difficult problem, which requires knowledge and experience in growth processes. Dislocation density is one of the most important parameters defining the quality of germanium crystal. In this paper, we have performed experimental study of dislocation density during 4-in. germanium crystal growth using the Czochralski method and comprehensive unsteady modeling of the same crystal growth processes, taking into account global heat transfer, melt flow and melt/crystal interface shape evolution. Thermal stresses in the crystal and their relaxation with generation of dislocations within the Alexander-Haasen model have been calculated simultaneously with crystallization dynamics. Comparison to experimental data showed reasonable agreement for the temperature, interface shape and dislocation density in the crystal between calculation and experiment.

Mechanism of Strain Rate Effect Based on Dislocation Theory

International Nuclear Information System (INIS)

Kun, Qin; Shi-Sheng, Hu; Li-Ming, Yang

2009-01-01

Based on dislocation theory, we investigate the mechanism of strain rate effect. Strain rate effect and dislocation motion are bridged by Orowan's relationship, and the stress dependence of dislocation velocity is considered as the dynamics relationship of dislocation motion. The mechanism of strain rate effect is then investigated qualitatively by using these two relationships although the kinematics relationship of dislocation motion is absent due to complicated styles of dislocation motion. The process of strain rate effect is interpreted and some details of strain rate effect are adequately discussed. The present analyses agree with the existing experimental results. Based on the analyses, we propose that strain rate criteria rather than stress criteria should be satisfied when a metal is fully yielded at a given strain rate. (condensed matter: structure, mechanical and thermal properties)

Piles of dislocation loops in real crystals

International Nuclear Information System (INIS)

Dubinko, V.I.; Turkin, A.A.; Yanovskij, V.V.

1985-01-01

Behaviour of piles of dislocation loops in crystals was studied in order to define metal swelling under irradiation. Energy of pile interaction with point defects and intrinsic pile energy are studied in the framework of the linear elasticity theory. Preference of dislocation pile calculated in the paper decreases with radiation dose hence, material swelling rate also decreases. Creation of conditions, which assume an existence of piles of dislocation loops being stable under irradiation, is of particular interest

Axillary artery injury secondary to inferior shoulder dislocation.

Science.gov (United States)

Plaga, Brad R; Looby, Peter; Feldhaus, Steven J; Kreutzmann, Karl; Babb, Aaron

2010-11-01

Dislocation injuries of the glenohumeral joint are common in the general public and generally are corrected without complication. One serious complication with shoulder dislocations, or the subsequent reduction, is a lesion to the axillary artery. This specific complication is most frequently seen in the elderly population, where vascular structures have become less flexible. Also, these injuries are most common in association with anterior dislocations of the shoulder. To bring awareness to the possibility of axillary artery injury with inferior dislocation of the shoulder, the treatment options, and a review. We report a 15-year-old male athlete who inferiorly dislocated his shoulder during wrestling practice. The injury was reduced at the scene with manual traction and the patient was transferred to our clinic for evaluation. The patient was determined to have a pseudoaneurysm of the axillary artery, and the history and treatment of the illness are presented. Axillary artery injuries secondary to shoulder dislocations are rare, especially in the young athlete, and proper recognition and treatment offer patients a full recovery. Copyright © 2010. Published by Elsevier Inc.

Dynamics of muscle strength improvement during isokinetic rehabilitation of athletes with ACL rupture and chondromalacia patellae.

Science.gov (United States)

Desnica Bakrac, N

2003-03-01

To assess quantitatively dynamics and extent of the increase in muscle strength during isokinetic rehabilitation. daily measurements of muscle strength; detailed testing at the beginning and at the end of rehabilitation. Cybex Rehabilitation Center, Zagreb. 44 athletes (31 m, 13 F, age 16-35), 3 injury-defined groups: athletes with ACL rupture (non-reconstructed and reconstructed) and chondromalacia patellae. all subjects underwent isokinetic rehabilitation on Cybex Orthotron KT2 device, using individually designed protocols (extension and flexion exercises, concentric muscle contractions, 15 treatments). monitoring of daily progress on rehabilitation device and detailed testing on diagnostic device. All patients showed considerable improvement. Muscle strength improved on average 141% (SD=110) in ACL-reconstructed group, 144% (SD=130) for chondromalacia patellae group and 150% (SD=74) for ACL-non-reconstructed group, comparing to initial strength. Dynamic status tested on Cybex Otrhotron diagnostic device prior and after rehabilitation strongly correlated with final progress monitored on the rehabilitation device. Isokinetic rehabilitation is a quick and effective method in treating knee injuries in athletes. Both types of objective criteria have shown significant increase in muscle strength. The improvement of muscle strength was on the average 149% (SD=101), which is about 10% daily for 15 treatments. The greatest progress, 19% per day, occurred during first five days. The athletes were able to resume their sport activities as follows: patients from chondromalacia patellae group, and most of them from the non-reconstructed ACL group were back in competition within a month, while 75% from the ACL reconstructed group came back within 3 months, and the rest of them within 5 months.

The ''hot patella'' sign: is it of any clinical significance. Concise communication

International Nuclear Information System (INIS)

Fogelman, I.; McKillop, J.H.; Gray, H.W.

1983-01-01

The presence of the ''hot patella'' sign was evaluated in a prospective study of 200 consecutive bone scans, and in a review of scans from 148 patients with various metabolic bone disorders and 61 patients with lung carcinoma. The incidence was found to be 31%, 26% and 31% respectively. This sign is an extremely common scan finding and may be seen in association with a wide variety of disorders. It is concluded that this sign cannot be considered to be of diagnostic value

Electron-dislocation interaction at low temperatures. Progress report

International Nuclear Information System (INIS)

1978-01-01

The interaction of mobile dislocations with electrons in copper and copper alloys has shown that dislocation motion in copper, at low temperature, can be treated as an analog of an underdamped oscillator. We have also shown that the viscous drag on mobile dislocations in type II superconductors can be treated as an acoustic attenuation of an elastic wave

Formation of disorientations in dislocation structures during plastic deformation

DEFF Research Database (Denmark)

Pantleon, W.

2002-01-01

Disorientations developing during plastic deformation in dislocation structures are investigated. Based on expected mechanisms for the formation of different types of dislocation boundaries (statistical trapping of dislocations or differently activated slip systems) the formation of the disorient...

Thermodynamic theory of dislocation-enabled plasticity

International Nuclear Information System (INIS)

Langer, J. S.

2017-01-01

The thermodynamic theory of dislocation-enabled plasticity is based on two unconventional hypotheses. The first of these is that a system of dislocations, driven by external forces and irreversibly exchanging heat with its environment, must be characterized by a thermodynamically defined effective temperature that is not the same as the ordinary temperature. The second hypothesis is that the overwhelmingly dominant mechanism controlling plastic deformation is thermally activated depinning of entangled pairs of dislocations. This paper consists of a systematic reformulation of this theory followed by examples of its use in analyses of experimentally observed phenomena including strain hardening, grain-size (Hall-Petch) effects, yielding transitions, and adiabatic shear banding.

Pair Interaction of Dislocations in Two-Dimensional Crystals

Science.gov (United States)

Eisenmann, C.; Gasser, U.; Keim, P.; Maret, G.; von Grünberg, H. H.

2005-10-01

The pair interaction between crystal dislocations is systematically explored by analyzing particle trajectories of two-dimensional colloidal crystals measured by video microscopy. The resulting pair energies are compared to Monte Carlo data and to predictions derived from the standard Hamiltonian of the elastic theory of dislocations. Good agreement is found with respect to the distance and temperature dependence of the interaction potential, but not regarding the angle dependence where discrete lattice effects become important. Our results on the whole confirm that the dislocation Hamiltonian allows a quantitative understanding of the formation and interaction energies of dislocations in two-dimensional crystals.

Dislocation Structures in Creep-deformed Polycrystalline MgO

DEFF Research Database (Denmark)

Bilde-Sørensen, Jørgen

1972-01-01

dislocation segments lie in their slip or climb planes. On the basis of this structure, a model is proposed in which glide is the principal cause of deformation but the rate-limiting process, i.e. annealing of the network, is diffusion-controlled. Theoretical estimates and experimental results agree within 1...... energy of 76 ± 12 kcal/mol. The creep rate is independent of grain size. The dislocation structure was investigated by transmission electron microscopy. The total dislocation density follows the relation, σ=bG√ρ, commonly found for metals. The dislocations form a 3-dimensional network in which many...

Osteochondritis dissecans of the patella in a XVII century player of the Florentine historic kickball.

Science.gov (United States)

Lippi, Donatella; Matucci-Cerinic, Marco; Villari, Natale; Fornaciari, Gino; Mascalchi, Mario

2010-03-01

We report a case of osteochondritis dissecans in the patella of Francesco de' Medici, Prince of Capistrano, who lived from 1594 to 1614. He was known to play Florentine kick ball, a precursor of Rugby and American football, and speculate that trauma from this activity may have led to the lesion. Copyright 2009 Elsevier B.V. All rights reserved.

Thermal activation of dislocations in large scale obstacle bypass

Science.gov (United States)

Sobie, Cameron; Capolungo, Laurent; McDowell, David L.; Martinez, Enrique

2017-08-01

Dislocation dynamics simulations have been used extensively to predict hardening caused by dislocation-obstacle interactions, including irradiation defect hardening in the athermal case. Incorporating the role of thermal energy on these interactions is possible with a framework provided by harmonic transition state theory (HTST) enabling direct access to thermally activated reaction rates using the Arrhenius equation, including rates of dislocation-obstacle bypass processes. Moving beyond unit dislocation-defect reactions to a representative environment containing a large number of defects requires coarse-graining the activation energy barriers of a population of obstacles into an effective energy barrier that accurately represents the large scale collective process. The work presented here investigates the relationship between unit dislocation-defect bypass processes and the distribution of activation energy barriers calculated for ensemble bypass processes. A significant difference between these cases is observed, which is attributed to the inherent cooperative nature of dislocation bypass processes. In addition to the dislocation-defect interaction, the morphology of the dislocation segments pinned to the defects play an important role on the activation energies for bypass. A phenomenological model for activation energy stress dependence is shown to describe well the effect of a distribution of activation energies, and a probabilistic activation energy model incorporating the stress distribution in a material is presented.

Dechanneling by dislocation loops

International Nuclear Information System (INIS)

Chalant, Gerard.

1976-09-01

Ion implantation always induces the creation of dislocation loops. When the damage profile is determined by a backscattering technique, the dechanneling by these loops is implicitely at the origin of these measurements. The dechanneling of alpha particles by dislocation loops produced by the coalescence of quenched-in vacancies in aluminium is studied. The dechanneling and the concentration of loops were determined simultaneously. The dechanneling width around dislocation was found equal to lambda=6A, both for perfect and imperfect loops having a mean diameter d=250A. In the latter case, a dechanneling probability chi=0.34 was determined for the stacking fault, in good agreement with previous determination in gold. A general formula is proposed which takes into account the variation of lambda with the curvature (or the diameter d) of the loops. Finally, by a series of isothermal anneals, the self-diffusion energy ΔH of aluminium was measured. The value obtained ΔH=1.32+-0.10eV is in good agreement with the values obtained by other methods [fr

Lens dislocation has a possible relationship with laser iridotomy

Directory of Open Access Journals (Sweden)

Mutoh T

2012-12-01

Full Text Available Tetsuya Mutoh,1,2 Kevin F Barrette,2 Yukihiro Matsumoto,1 Makoto Chikuda11Department of Ophthalmology, Dokkyo Medical University Koshigaya Hospital, Koshigaya City, Saitama, Japan; 2Department of Ophthalmology, Boston University School of Medicine, Boston, MA, USAAbstract: We report our recent experience of four eyes with spontaneous lens dislocation in four patients with no history of trauma or any systemic disease associated with zonular dialysis. Lens dislocation developed with 0.5 to 6 months following laser iridotomy. All patients were male and two eyes were complicated with acute primary angle closure glaucoma preoperatively. Case 1 showed bilateral lens dislocation, while cases 2 and 3 involved unilateral lens dislocation. Cases 2 and 3 showed lenses completely dislocated into the vitreous cavity. All cases needed lens removal and scleral fixation of intraocular lenses. Final visual acuity was 1.2 in all cases. We suspect that laser iridotomy may induce localized zonular dialysis that results in progressive zonular weakness, leading to lens dislocation.Keywords: lens dislocation, laser iridotomy, primary angle closure glaucoma

Thermally activated dislocation motion including inertial effects in solid solutions

International Nuclear Information System (INIS)

Isaac, R.D.

1977-01-01

Dislocation motion through an array of obstacles is considered in terms of the potential energy of the dislocation as it moves through the array. The obstacles form a series of potential wells and barriers which can trap the dislocations. The effect of thermal fluctuations and of a viscous drag on the motion of the dislocation is investigated by analogy with Brownian motion in a field of force. The rate of escape of a trapped dislocation is found to depend on the damping coefficient only for a large viscous drag. The probability that a dislocation will be trapped by a well or barrier is found to depend on the damping coefficient for a small viscous drag. This inertial effect determines how far a dislocation will travel after breaking away from an obstacle

Influence of strain on dislocation core in silicon

Science.gov (United States)

Pizzagalli, L.; Godet, J.; Brochard, S.

2018-05-01

First principles, density functional-based tight binding and semi-empirical interatomic potentials calculations are performed to analyse the influence of large strains on the structure and stability of a 60? dislocation in silicon. Such strains typically arise during the mechanical testing of nanostructures like nanopillars or nanoparticles. We focus on bi-axial strains in the plane normal to the dislocation line. Our calculations surprisingly reveal that the dislocation core structure largely depends on the applied strain, for strain levels of about 5%. In the particular case of bi-axial compression, the transformation of the dislocation to a locally disordered configuration occurs for similar strain magnitudes. The formation of an opening, however, requires larger strains, of about 7.5%. Furthermore, our results suggest that electronic structure methods should be favoured to model dislocation cores in case of large strains whenever possible.

An investigation of green iridescence on the mollusc Patella granatina

Energy Technology Data Exchange (ETDEWEB)

Brink, D J; Berg, N G van der [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa)

2005-01-21

In this paper we investigate the relatively rare phenomenon of iridescence on the outer surface of seashells (not the well known pearly inner surfaces). Using reflection spectroscopy and scanning electron microscopy we show that rows of iridescent green spots on the mollusc Patella granatina are caused by a thin-film stack buried about 100 {mu}m below the rough outer surface of the shell. The high-density layers in the stack seem to be made of crystalline aragonite, but according to Raman spectroscopy and ellipsometry measurements the low-density layers as well as the bulk of the shell wall are a mixture of porous aragonite and organic materials such as carotenoids.

Primary tumors of the patella. A review of 42 cases

Energy Technology Data Exchange (ETDEWEB)

Kransdorf, M.J. (Walter Reed Army Medical Center, Washington, DC (USA). Dept. of Radiology; University of the Health Sciences, Bethesda, MD (USA). Dept. of Radiology and Nuclear Medicine); Moser, R.P. Jr. (Armed Forces Inst. of Pathology, Washington, DC (USA). Dept. of Radiologic Pathology; University of the Health Sciences, Bethesda, MD (USA). Dept. of Radiology and Nuclear Medicine); Vinh, T.N. (Armed Forces Inst. of Pathology, Washington, DC (USA). Dept. of Orthopaedic Surgery); Aoki, J. (Armed Forces Inst. of Pathology, Washington, DC (USA). Dept. of Radiologic Pathology); Callaghan, J.J. (Duke Univ., Durham, NC (USA). Dept. of Orthopaedic Surgery)

1989-08-01

This study reports 42 cases of histologically proven and radiographically correlated primary patellar tumors. Despite diverse histologic diagnoses, the radiographic appearanaces of benign as opposed to malignant patellar neoplasms are essentially indistinguishable. Although the literature suggests that giant cell tumor is the most frequent benign tumor of the patella, the most common benign neoplasm in this series is chondroblastoma (16 cases). Only four primary malignant lesions were encountered, three cases of lymphoma and one case of hemangioendothelioma. Since 38 (90%) of the 42 cases were benign, a benign etiology should be strongly favored, notwithstanding the radiographic appearance, whenever a primary patellar tumor is encountered. (orig.).

Interferometric SAR and land deformation. Analysis using the dislocation model; Interferometric SAR to chikaku hendo. Dislocation model wo mochiita kaiseki

Energy Technology Data Exchange (ETDEWEB)

Matsushima, J; Otaki, T; Tanaka, A; Miyazaki, Y [Geological Survey of Japan, Tsukuba (Japan)

1996-05-01

The diastrophism by the earthquake-induced dislocation is investigated by interferometry (INSAR) which represents the diastrophism by the interference fringes of equiphase difference lines. A joint research group at Geographical Survey Institute and National Space Development Agency showed the diastrophism in the vicinity of the ground surfaces before and after the Hyogoken Nanbu Earthquake by the INSAR interference images in 1995. This paper discusses the effects of observation in the vision line direction from the satellite and dislocation parameters on the interference images. The dislocation model uses a slanted rectangular model in a semi-infinite medium, to calculate static displacements and strain distributions at the ground surface, when dislocation changes. It is found that the INSAR interference images, detecting displacements in the vision line direction from the satellite, significantly change as the vision line direction changes, and that the actual displacement cannot be given by the images alone. This paper also shows sensitivity of the interference images to the dislocation parameters. 3 refs., 9 figs., 1 tab.

Riemann–Cartan Geometry of Nonlinear Dislocation Mechanics

KAUST Repository

Yavari, Arash; Goriely, Alain

2012-01-01

but vanishing non-metricity. Torsion of the material manifold is identified with the dislocation density tensor of nonlinear dislocation mechanics. Using Cartan's moving frames we construct the material manifold for several examples of bodies with distributed

On verification of a theory in dislocation plasticity

International Nuclear Information System (INIS)

Ng, D.H.Y.; Lee, L.H.N.

1981-01-01

In the past twenty years, many attempts to unify the theories of macroplasticity and microplasticity in polycrystalline materials have been made. Several major approaches have been suggested namely: the geometrical approach, the analytical approach, the phenomenological approach and the internal variables approach. To verify the plasticity theory based on any one of the above models, detail experimental data including microstructural quantities such as dislocation density, dislocation speed, etc. are required. Unfortunately, there were some difficulties in evaluating dislocation speed and dealing with the term 'mobile fraction' of dislocation density. Therefore, an experimental verification of such plasticity theory has not been made. A dislocation velocity equation based on a thermally activated model is used. A set of plastic strain rate equations for polycrystalline materials formulated by analyzing dislocation dynamics in a statistical approach are presented. In order to evaluate the activation free energy, Gibbs' modified tetragonal distortion model is used together with some measurements obtained from electron micrographs. Experimental results on the dynamic yielding and fracture of 6061-T6 aluminum alloy tubings under biaxial loadings obtained by Ng, Delich and Lee are used. In dealing with 'mobile fraction', Gilman's suggestion is adopted. (orig./HP)

Patellafrakturen im Kindesalter

DEFF Research Database (Denmark)

Schmal, H.; Seif El Nasr, M.; Schlickewei, W.

2000-01-01

not surprisingly only 4 cases were noticed. All patients were males and accidents happend during leasure activities. Relevant accompanying injuries were not seen. In 3 of 4 cases an effusion of the knee joint was diagnosed. A virtually not dislocated avulsion of the inferior patella pole was treated without...

Dislocation core structures in (0001) InGaN

International Nuclear Information System (INIS)

Rhode, S. L.; Sahonta, S.-L.; Kappers, M. J.; McAleese, C.; Humphreys, C. J.; Horton, M. K.; Haigh, S. J.; Pennycook, T. J.; Dusane, R. O.; Moram, M. A.

2016-01-01

Threading dislocation core structures in c-plane GaN and In x Ga 1−x N (0.057 ≤ x ≤ 0.20) films were investigated by aberration-corrected scanning transmission electron microscopy. a-type dislocations are unaffected by alloying with indium and have a 5/7-atom ring core structure in both GaN and In x Ga 1−x N. In contrast, the dissociation lengths of (a + c)-type dislocations are reduced, and new 7/4/9-atom ring and 7/4/8/5-atom ring core structures were observed for the dissociated (a + c)-type dislocations in In x Ga 1−x N, which is associated with the segregation of indium near (a + c)-type and c-type dislocation cores in In x Ga 1−x N, consistent with predictions from atomistic Monte Carlo simulations.

Strain field mapping of dislocations in a Ge/Si heterostructure.

Directory of Open Access Journals (Sweden)

Quanlong Liu

Full Text Available Ge/Si heterostructure with fully strain-relaxed Ge film was grown on a Si (001 substrate by using a two-step process by ultra-high vacuum chemical vapor deposition. The dislocations in the Ge/Si heterostructure were experimentally investigated by high-resolution transmission electron microscopy (HRTEM. The dislocations at the Ge/Si interface were identified to be 90° full-edge dislocations, which are the most efficient way for obtaining a fully relaxed Ge film. The only defect found in the Ge epitaxial film was a 60° dislocation. The nanoscale strain field of the dislocations was mapped by geometric phase analysis technique from the HRTEM image. The strain field around the edge component of the 60° dislocation core was compared with those of the Peierls-Nabarro and Foreman dislocation models. Comparison results show that the Foreman model with a = 1.5 can describe appropriately the strain field around the edge component of a 60° dislocation core in a relaxed Ge film on a Si substrate.

Strain field mapping of dislocations in a Ge/Si heterostructure.

Science.gov (United States)

Liu, Quanlong; Zhao, Chunwang; Su, Shaojian; Li, Jijun; Xing, Yongming; Cheng, Buwen

2013-01-01

Ge/Si heterostructure with fully strain-relaxed Ge film was grown on a Si (001) substrate by using a two-step process by ultra-high vacuum chemical vapor deposition. The dislocations in the Ge/Si heterostructure were experimentally investigated by high-resolution transmission electron microscopy (HRTEM). The dislocations at the Ge/Si interface were identified to be 90° full-edge dislocations, which are the most efficient way for obtaining a fully relaxed Ge film. The only defect found in the Ge epitaxial film was a 60° dislocation. The nanoscale strain field of the dislocations was mapped by geometric phase analysis technique from the HRTEM image. The strain field around the edge component of the 60° dislocation core was compared with those of the Peierls-Nabarro and Foreman dislocation models. Comparison results show that the Foreman model with a = 1.5 can describe appropriately the strain field around the edge component of a 60° dislocation core in a relaxed Ge film on a Si substrate.

Dislocation: First Aid

Science.gov (United States)

... or a collision during contact or high-speed sports. Dislocation usually involves the body's larger joints. In adults, the most common site of the injury is the shoulder. In children, it's the elbow. ...

Results of hip arthroplasty using Paavilainen technique in patients with congenitally dislocated hip

Directory of Open Access Journals (Sweden)

R. M. Tikhilov

2014-01-01

Full Text Available The purpose of the study was to analyze the medium- and long-term results of hip arthroplasty using Paavilainen technique in patients with the congenitally dislocated hip. Methods: From 2001 to 2012 180 operations were carried out were using the Paavilainen technique in 140 patients with high dislocation of the hip (Crowe IV. All patients were clinically evaluated using the Harris Hip Score (HHS, VAS and radiography. Statistical analysis was performed using the Pearson correlation coefficients, multiple regression analysis and classification trees analysis. Results: The average Harris score improved from preoperative 41.6 (40,3-43,5 to 79.3 (77,9-82,7 at final follow-up, and the difference was significant. Early complications were 9% (the most frequent were fractures of the proximal femur, later - 16.7% (pseudoarthrosis of the greater trochanter, 13.9%; disclocations-1,1%, aseptic loosening of the components - 1.7%, reoperation performed in 8.3% of cases. Such factors as age and limb length has statistically significant effect on functional outcomes. Established predictive model allows to get the best possible functional outcome in such patients with severe dysplasia. Conclusions: Total Hip arthroplasty using the Paavilainen technique is an effective method of surgical treatment in patients with the congenitally dislocated hip, but it is technically difficult operation with a high incidence of complications in comparison with standard primary total hip replacement.

Posterior dislocation of the sternoclavicular joint leading to mediastinal compression.

Science.gov (United States)

Jougon, J B; Lepront, D J; Dromer, C E

1996-02-01

Dislocations of the sternoclavicular joint are uncommon, and the posterior variety have a potential for considerable morbidity. We report a case with compression of the vital structures within the superior mediastinum. It was a rugby player getting run over by the scrum. The mechanism was an indirect force exerted forward and laterally against the shoulder. The patient complained of pain and dysphagia. A systolic right cervical murmur was heard. Angiography was normal and esophagography showed extrinsic esophageal compression. Surgical reduction was performed because there was a slight pneumomediastinum on the computed tomography. This case report demonstrates the mechanism, complications, and treatment of such a lesion.

Rare Inferior Shoulder Dislocation (Luxatio Erecta

Directory of Open Access Journals (Sweden)

Hakan Cift

2015-01-01

Full Text Available Although shoulder dislocations have been seen very frequently, inferior dislocation of shoulder constitutes only 0.5% of all shoulder dislocations. We share our 4 patients with luxatio erecta and present their last clinical control. 2 male and 2 female Caucasian patients were diagnosed as luxatio erecta. Patients’ ages were 78, 62, 65, and 76. All patients’ reduction was done by traction-abduction and contour traction maneuver in the operating room. The patients had no symptoms and no limitation of range of motion of their shoulder at their last control. Luxatio erecta is seen rarely, and these patients may have neurovascular injury. These patients should be carefully examined and treated by the orthopaedic and traumatology surgeons.

Rare Inferior Shoulder Dislocation (Luxatio Erecta)

Science.gov (United States)

Cift, Hakan; Soylemez, Salih; Demiroglu, Murat; Ozkan, Korhan; Ozden, Vahit Emre; Ozkut, Afsar T.

2015-01-01

Although shoulder dislocations have been seen very frequently, inferior dislocation of shoulder constitutes only 0.5% of all shoulder dislocations. We share our 4 patients with luxatio erecta and present their last clinical control. 2 male and 2 female Caucasian patients were diagnosed as luxatio erecta. Patients' ages were 78, 62, 65, and 76. All patients' reduction was done by traction-abduction and contour traction maneuver in the operating room. The patients had no symptoms and no limitation of range of motion of their shoulder at their last control. Luxatio erecta is seen rarely, and these patients may have neurovascular injury. These patients should be carefully examined and treated by the orthopaedic and traumatology surgeons. PMID:25883820

Asymptotic analysis of a pile-up of regular edge dislocation walls

KAUST Repository

Hall, Cameron L.

2011-12-01

The idealised problem of a pile-up of regular dislocation walls (that is, of planes each containing an infinite number of parallel, identical and equally spaced dislocations) was presented by Roy et al. [A. Roy, R.H.J. Peerlings, M.G.D. Geers, Y. Kasyanyuk, Materials Science and Engineering A 486 (2008) 653-661] as a prototype for understanding the importance of discrete dislocation interactions in dislocation-based plasticity models. They noted that analytic solutions for the dislocation wall density are available for a pile-up of regular screw dislocation walls, but that numerical methods seem to be necessary for investigating regular edge dislocation walls. In this paper, we use the techniques of discrete-to-continuum asymptotic analysis to obtain a detailed description of a pile-up of regular edge dislocation walls. To leading order, we find that the dislocation wall density is governed by a simple differential equation and that boundary layers are present at both ends of the pile-up. © 2011 Elsevier B.V.

Asymptotic analysis of a pile-up of regular edge dislocation walls

KAUST Repository

Hall, Cameron L.

2011-01-01

The idealised problem of a pile-up of regular dislocation walls (that is, of planes each containing an infinite number of parallel, identical and equally spaced dislocations) was presented by Roy et al. [A. Roy, R.H.J. Peerlings, M.G.D. Geers, Y. Kasyanyuk, Materials Science and Engineering A 486 (2008) 653-661] as a prototype for understanding the importance of discrete dislocation interactions in dislocation-based plasticity models. They noted that analytic solutions for the dislocation wall density are available for a pile-up of regular screw dislocation walls, but that numerical methods seem to be necessary for investigating regular edge dislocation walls. In this paper, we use the techniques of discrete-to-continuum asymptotic analysis to obtain a detailed description of a pile-up of regular edge dislocation walls. To leading order, we find that the dislocation wall density is governed by a simple differential equation and that boundary layers are present at both ends of the pile-up. © 2011 Elsevier B.V.

On the role of the patella, ACL and joint contact forces in the extension of the knee.

Directory of Open Access Journals (Sweden)

Daniel J Cleather

Full Text Available Traditional descriptions of the knee suggest that the function of the patella is to facilitate knee extension by increasing the moment arm of the quadriceps muscles. Through modelling and evidence from the literature it is shown in this paper that the presence of the patella makes the ability of the quadriceps to rotate the thigh greater than their ability to rotate the tibia. Furthermore, this difference increases as the knee is flexed, thus demonstrating a pattern that is consistent with many human movements. This paper also shows that the anterior cruciate ligament plays a previously unheralded role in extending the shank and that translation at the tibiofemoral and patellofemoral joints is important in improving the capacity for thigh rotation when the knee is flexed. This study provides new insights as to how the structure of the knee is adapted to its purpose and illustrates how the functional anatomy of the knee contributes to its extension function.

Surgery for acute subaxial traumatic central cord syndrome without fracture or dislocation.

Science.gov (United States)

Song, Joonsuk; Mizuno, Junichi; Nakagawa, Hiroshi; Inoue, Tatsushi

2005-05-01

Twenty-two patients with subaxial acute traumatic central cord syndrome (CCS) without fracture or dislocation who underwent surgery between 1995 and 2002 were reviewed, retrospectively. There were 13 males and nine females ranging in age from 24 to 84 years (mean 61.2). Falls were the most common injury (68%), followed by motor vehicle accidents (32%). All patients had dynamic cervical lateral radiographs and magnetic resonance imaging (MRI). Cord compression was present in all cases and cervical instability in 11. Associated pathology included disc herniation in seven patients, cervical spondylosis (CS) in 11 and ossification of the posterior longitudinal ligament (OPLL) in four. Anterior decompression and fusion was performed in 12 patients with 1- or 2-level lesions. Posterior decompression and fusion was performed for multilevel lesions in 11 patients, including one patient who required re-operation. The interval between injury and surgery ranged from 1 to 37 days (mean 8.0). Postoperatively, all patients improved clinically. We conclude that surgical management of subaxial acute traumatic CCS without fracture or dislocation improved neurological status and prevented delayed neurological deterioration in our patients.

Positron-trapping mechanism at dislocations in Zn

DEFF Research Database (Denmark)

Hidalgo, Carlos; Linderoth, Søren; Diego, Nieves de

1987-01-01

the average lifetime and the intensity of the long component decrease with increasing temperature. The experimental results are very well described in terms of a generalized trapping model where it is assumed that positrons become trapped in deep traps (jogs) via shallow traps (dislocation lines......). The temperature dependence of the positron-lifetime spectra below 120 K is attributed to the temperature dependence of the trapping rate to the dislocation line. The experimental results have demonstrated that detrapping processes from the dislocation line take place above 120 K. The positron binding energy...

Core structure, dislocation energy and Peierls stress for 1/3112-bar 0 edge dislocations with (0001) and {11-bar 00} slip planes in α-Zr

International Nuclear Information System (INIS)

Voskoboinikov, R.E.; Osetsky, Yu.N.; Bacon, D.J.

2005-01-01

Atomic-scale simulations of edge dislocations of the 1/3112-bar 0(0001) and 1/3112-bar 0{11-bar 00} slip systems have been carried out using a Finnis-Sinclair-type interatomic potential for α-zirconium. The distribution of atomic displacements in the dislocation core shows that in this model the edge dislocation in the basal plane dissociates into two Shockley partials whereas the dislocation in the prism plane remains undissociated. The effective core radius and core energy are estimated, and dislocation response to increasing applied shear strain is investigated. The core properties and the critical stress for dislocation glide (Peierls stress) depend sensitively on whether the core extends or not

Mid-term results of lateral unicondylar mobile bearing knee arthroplasty: a multicentre study of 363 cases.

Science.gov (United States)

Walker, T; Zahn, N; Bruckner, T; Streit, M R; Mohr, G; Aldinger, P R; Clarius, M; Gotterbarm, T

2018-01-01

The aim of this independent multicentre study was to assess the mid-term results of mobile bearing unicondylar knee arthroplasty (UKA) for isolated lateral osteoarthritis of the knee joint. We retrospectively evaluated 363 consecutive, lateral UKAs (346 patients) performed using the Oxford domed lateral prosthesis undertaken in three high-volume knee arthroplasty centres between 2006 and 2014. Mean age of the patients at surgery was 65 years (36 to 88) with a mean final follow-up of 37 months (12 to 93) RESULTS: A total of 36 (10.5%) patients underwent revision surgery, giving a survival rate of 90.1% at three years (95% confidence intervals (CI) 86.1 to 93.1; number at risk: 155) and 85.0% at five years (95% CI 77.9 to 89.9; number at risk: 43). Dislocation of the mobile bearing occurred in 18 patients (5.6%) at three years (95% CI 1.0 to 16.4; number at risk: 154) and in 20 patients (8.5%) at five years (95% CI 1.0 to 27.0; number at risk: 42). There were no significant differences in the dislocation rate between the participating centres or the surgeons. We were not able to identify an effect of each surgeon's learning curve on the dislocation rate of the mobile bearing. The clinical outcome in patients without revision surgery at final follow-up was good to excellent, with a mean Oxford knee score of 40.3 (95% CI 39.4 to 41.2), a mean Tegner activity score of 3.2 (95% CI 3.1 to 3.3) and a mean University of California, Los Angeles score of 5.7 (95% CI 5.5 to 5.9). Our data, which consists of a high number of patients treated with mobile bearing UKA in the lateral compartment, indicates a high revision rate of 15% at five years with dislocation of the mobile bearing being the main reason for implant failure. Despite the good functional and clinical results and the high patient satisfaction in our study group, we therefore discontinued using mobile-bearing lateral UKA in favour of a fixed-bearing component. Cite this article: Bone Joint J 2018;100-B:42-9. ©2018

Irradiation-induced amorphization in split-dislocation cores

International Nuclear Information System (INIS)

Ovid'ko, I.A.; Rejzis, A.B.

1999-01-01

The model describing special splitting of lattice and grain-boundary dislocations as one of the micromechanisms of solid-phase amorphization in irradiated crystals is proposed. Calculation of energy characteristics of the process of dislocations special splitting is carried out [ru

Superolateral dislocation of the intact mandibular condyle associated with panfacial fracture: a case report and literature review.

Science.gov (United States)

Amaral, Márcio Bruno; Bueno, Sebastião Cristian; Silva, Alice Araújo Ferreira; Mesquita, Ricardo Alves

2011-06-01

Superolateral dislocation of the intact mandibular condyle (SDIMC) is rare. This case report focuses on a 15-year-old teenager who was involved in a motor vehicle accident as well a literature review regarding the SDIMC. Clinical examination demonstrated a diffuse edema in the midfacial area and a left lateral deflection of the mandible, including an open bite and a crepitation in the symphyseal region. Three-dimensional computed tomography scans were taken, which presented a superolateral dislocation of the left mandibular condyle as well as panfacial fracture. The patient was set in intermaxillary fixation for 2 weeks and underwent subsequent active jaw physiotherapy, the evaluation of which presented satisfactory results. This case study also presents a literature review, which demonstrated 21 well-documented cases of SDIMC. The patients' mean age was of 29 years. The male gender proved to be more prevalent, with road traffic collisions representing the most common form of accident. Type II, with unilateral dislocation, proved to be the most common. The mean reduction time was 7 days. The open methods were the most commonly used reduction methods. Mandible fracture was associated with dislocation in 82% of the cases, with other facial fractures appearing in only 23% of the cases. Patient follow up presented satisfactory results in 59% of the cases. © 2011 John Wiley & Sons A/S.

Dislocation core structures in Si-doped GaN

International Nuclear Information System (INIS)

Rhode, S. L.; Fu, W. Y.; Sahonta, S.-L.; Kappers, M. J.; Humphreys, C. J.; Horton, M. K.; Pennycook, T. J.; Dusane, R. O.; Moram, M. A.

2015-01-01

Aberration-corrected scanning transmission electron microscopy was used to investigate the core structures of threading dislocations in plan-view geometry of GaN films with a range of Si-doping levels and dislocation densities ranging between (5 ± 1) × 10 8  and (10 ± 1) × 10 9  cm −2 . All a-type (edge) dislocation core structures in all samples formed 5/7-atom ring core structures, whereas all (a + c)-type (mixed) dislocations formed either double 5/6-atom, dissociated 7/4/8/4/9-atom, or dissociated 7/4/8/4/8/4/9-atom core structures. This shows that Si-doping does not affect threading dislocation core structures in GaN. However, electron beam damage at 300 keV produces 4-atom ring structures for (a + c)-type cores in Si-doped GaN

Dislocation core structures in Si-doped GaN

Energy Technology Data Exchange (ETDEWEB)

Rhode, S. L., E-mail: srhode@imperial.ac.uk; Fu, W. Y.; Sahonta, S.-L.; Kappers, M. J.; Humphreys, C. J. [Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Horton, M. K. [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Pennycook, T. J. [SuperSTEM, STFC Daresbury Laboratories, Warrington WA4 4AD (United Kingdom); Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Dusane, R. O. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Moram, M. A. [Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom)

2015-12-14

Aberration-corrected scanning transmission electron microscopy was used to investigate the core structures of threading dislocations in plan-view geometry of GaN films with a range of Si-doping levels and dislocation densities ranging between (5 ± 1) × 10{sup 8} and (10 ± 1) × 10{sup 9} cm{sup −2}. All a-type (edge) dislocation core structures in all samples formed 5/7-atom ring core structures, whereas all (a + c)-type (mixed) dislocations formed either double 5/6-atom, dissociated 7/4/8/4/9-atom, or dissociated 7/4/8/4/8/4/9-atom core structures. This shows that Si-doping does not affect threading dislocation core structures in GaN. However, electron beam damage at 300 keV produces 4-atom ring structures for (a + c)-type cores in Si-doped GaN.

Dislocation core structures in (0001) InGaN

Energy Technology Data Exchange (ETDEWEB)

Rhode, S. L.; Sahonta, S.-L.; Kappers, M. J.; McAleese, C.; Humphreys, C. J. [Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Horton, M. K. [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Haigh, S. J. [School of Materials, University of Manchester, Manchester M13 9PL (United Kingdom); SuperSTEM, STFC Daresbury Laboratories, Warrington WA4 4AD (United Kingdom); Pennycook, T. J. [SuperSTEM, STFC Daresbury Laboratories, Warrington WA4 4AD (United Kingdom); Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Dusane, R. O. [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay, Mumbai 400076 (India); Moram, M. A. [Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom)

2016-03-14

Threading dislocation core structures in c-plane GaN and In{sub x}Ga{sub 1−x}N (0.057 ≤ x ≤ 0.20) films were investigated by aberration-corrected scanning transmission electron microscopy. a-type dislocations are unaffected by alloying with indium and have a 5/7-atom ring core structure in both GaN and In{sub x}Ga{sub 1−x}N. In contrast, the dissociation lengths of (a + c)-type dislocations are reduced, and new 7/4/9-atom ring and 7/4/8/5-atom ring core structures were observed for the dissociated (a + c)-type dislocations in In{sub x}Ga{sub 1−x}N, which is associated with the segregation of indium near (a + c)-type and c-type dislocation cores in In{sub x}Ga{sub 1−x}N, consistent with predictions from atomistic Monte Carlo simulations.

Self-force on dislocation segments in anisotropic crystals

International Nuclear Information System (INIS)

Fitzgerald, S P; Aubry, S

2010-01-01

A dislocation segment in a crystal experiences a 'self-force', by virtue of the orientation dependence of its elastic energy. If the crystal is elastically isotropic, this force is manifested as a couple acting to rotate the segment toward the lower energy of the pure screw orientation (i.e. acting to align the dislocation line with its Burgers vector). If the crystal is anisotropic, there are additional contributions to the couple, arising from the more complex energy landscape of the lattice itself. These effects can strongly influence the dynamic evolution of dislocation networks, and via their governing role in dislocation multiplication phenomena, control plastic flow in metals. In this paper we develop a model for dislocation self-forces in a general anisotropic crystal, and briefly consider the technologically important example of α-iron, which becomes increasingly anisotropic as the temperature approaches that of the α-γ phase transition at 912 0 C.

Interaction energy of interface dislocation loops in piezoelectric bi-crystals

Directory of Open Access Journals (Sweden)

Jianghong Yuan

2017-03-01

Full Text Available Interface dislocations may dramatically change the electric properties, such as polarization, of the piezoelectric crystals. In this paper, we study the linear interactions of two interface dislocation loops with arbitrary shape in generally anisotropic piezoelectric bi-crystals. A simple formula for calculating the interaction energy of the interface dislocation loops is derived and given by a double line integral along two closed dislocation curves. Particularly, interactions between two straight segments of the interface dislocations are solved analytically, which can be applied to approximate any curved loop so that an analytical solution can be also achieved. Numerical results show the influence of the bi-crystal interface as well as the material orientation on the interaction of interface dislocation loops.

Atomistically determined phase-field modeling of dislocation dissociation, stacking fault formation, dislocation slip, and reactions in fcc systems

Science.gov (United States)

Rezaei Mianroodi, Jaber; Svendsen, Bob

2015-04-01

The purpose of the current work is the development of a phase field model for dislocation dissociation, slip and stacking fault formation in single crystals amenable to determination via atomistic or ab initio methods in the spirit of computational material design. The current approach is based in particular on periodic microelasticity (Wang and Jin, 2001; Bulatov and Cai, 2006; Wang and Li, 2010) to model the strongly non-local elastic interaction of dislocation lines via their (residual) strain fields. These strain fields depend in turn on phase fields which are used to parameterize the energy stored in dislocation lines and stacking faults. This energy storage is modeled here with the help of the "interface" energy concept and model of Cahn and Hilliard (1958) (see also Allen and Cahn, 1979; Wang and Li, 2010). In particular, the "homogeneous" part of this energy is related to the "rigid" (i.e., purely translational) part of the displacement of atoms across the slip plane, while the "gradient" part accounts for energy storage in those regions near the slip plane where atomic displacements deviate from being rigid, e.g., in the dislocation core. Via the attendant global energy scaling, the interface energy model facilitates an atomistic determination of the entire phase field energy as an optimal approximation of the (exact) atomistic energy; no adjustable parameters remain. For simplicity, an interatomic potential and molecular statics are employed for this purpose here; alternatively, ab initio (i.e., DFT-based) methods can be used. To illustrate the current approach, it is applied to determine the phase field free energy for fcc aluminum and copper. The identified models are then applied to modeling of dislocation dissociation, stacking fault formation, glide and dislocation reactions in these materials. As well, the tensile loading of a dislocation loop is considered. In the process, the current thermodynamic picture is compared with the classical mechanical

Fabrication of mesoscopic floating Si wires by introducing dislocations

International Nuclear Information System (INIS)

Motohashi, Mitsuya; Shimizu, Kazuya; Niwa, Masaaki; Suzuki, Toshiaki

2014-01-01

We fabricated a mesoscopic Si wire by introducing dislocations in a silicon wafer before HF anodization. The dislocations formed along the (111) crystal plane. The outline of the dislocation line was an inverted triangle. The resulting wire floated on a bridge girder and had a hybrid structure consisting of a porous layer and crystalline Si. The cross section of the wire had an inverted triangle shape. The wire formation mechanism is discussed in terms of carrier transport, crystal structure, and dislocation formation during anodization. (paper)

Fabrication of mesoscopic floating Si wires by introducing dislocations

Science.gov (United States)

Motohashi, Mitsuya; Shimizu, Kazuya; Suzuki, Toshiaki; Niwa, Masaaki

2014-12-01

We fabricated a mesoscopic Si wire by introducing dislocations in a silicon wafer before HF anodization. The dislocations formed along the (111) crystal plane. The outline of the dislocation line was an inverted triangle. The resulting wire floated on a bridge girder and had a hybrid structure consisting of a porous layer and crystalline Si. The cross section of the wire had an inverted triangle shape. The wire formation mechanism is discussed in terms of carrier transport, crystal structure, and dislocation formation during anodization.

Scattering of phonons by dislocations

International Nuclear Information System (INIS)

Anderson, A.C.

1979-01-01

By 1950, an explicit effort had been launched to use lattice thermal conductivity measurements in the investigation of defect structures in solids. This technique has been highly successful, especially when combined with the measurements of other properties such as optical absorption. One exception has been the study of dislocations. Although dislocations have a profound effect on the phonon thermal conductivity, the mechanisms of the phonon-dislocation interaction are poorly understood. The most basic questions are still debated in the literature. It therefore is pointless to attempt a quantitative comparison between an extensive accumulation of experimental data on the one hand, and the numerous theoretical models on the other. Instead, this chapter will attempt to glean a few qualitative conclusions from the existing experimental data. These results will then be compared with two general models which incorporate, in a qualitative manner, most of the proposed theories of the phonon-dislocation interaction. Until very recently, measurement of thermal conductivity was the only means available to probe the interaction between phonons and defects at phonon frequencies above the standard ultrasonic range of approx. = 10 9 Hz. The introductory paragraphs provide a brief review of the thermal-conductivity technique and the problems which are encountered in practice. There is also a brief presentation of the theoretical models and the complications that may occur in more realistic situations

Interaction of helium atoms with edge dislocations in α-Fe

International Nuclear Information System (INIS)

Heinisch, H.L.; Gao, F.; Kurtz, R.J.; Le, E.A.

2006-01-01

Formation energies, binding energies, and migration energies of interstitial He atoms in and near the core of an a/2 {1 1 0} edge dislocation in α-Fe are determined in atomistic simulations using conjugate gradient relaxation and the Dimer method for determining saddle point energies. Results are compared as a function of the proximity of the He to the dislocation core and the excess interstitial volume in regions around the dislocation. Interstitial He atoms have negative binding energy on the compression side of the dislocation and strong positive binding energy on the tension side. Even at low temperatures, interstitial He atoms in the vicinity of the dislocation easily migrate to the dislocation core, where they form crowdion interstitials oriented along the close-packed slip direction, with binding energies in excess of 2 eV. Crowdion interstitial He atoms diffuse along the dislocation core, transverse to the crowdion direction, with a migration energy of 0.4-0.5 eV

Tendoscopic Double-Row Suture Bridge Peroneal Retinaculum Repair for Recurrent Dislocation of Peroneal Tendons in the Ankle.

Science.gov (United States)

Nishimura, Akinobu; Nakazora, Shigeto; Ito, Naoya; Fukuda, Aki; Kato, Ko; Sudo, Akihiro

2016-06-01

Traumatic dislocation of peroneal tendons in the ankle is an uncommon lesion that mainly affects young adults. Unfortunately, most cases lead to recurrent dislocation of the peroneal tendons of the ankle (RPTD). Therefore, most cases need operative treatment. One of the most common operative procedures is superior peroneal retinaculum (SPR) repair. Recently, surgery for RPTD has been achieved with less invasive arthroscopic procedures. In this article, tendoscopic surgery for RPTD using a double-row suture bridge technique is introduced. This technique consists of debridement of the lateral aspect of the fibula under an intrasheath pseudo-cavity, suture anchor insertion into the fibular ridge, and reattachment of the SPR to the fibula using a knotless anchor screwed into the lateral aspect of the fibula. This technique mimics the double-row suture bridge technique for rotator cuff tear repair. The double-row suture bridge technique requires more surgical steps than the single-row technique, but it provides a wider bone-SPR contact surface and tighter fixation than the single-row technique. This procedure is an attractive option because it is less invasive and has achieved results similar to open procedures.

Edge dislocations in dicalcium silicates: Experimental observations and atomistic analysis

International Nuclear Information System (INIS)

Shahsavari, Rouzbeh; Chen, Lu; Tao, Lei

2016-01-01

Understanding defects and influence of dislocations on dicalcium silicates (Ca 2 SiO 4 ) is a challenge in cement science. We report a high-resolution transmission electron microscopy image of edge dislocations in Ca 2 SiO 4 , followed by developing a deep atomic understanding of the edge dislocation-mediated properties of five Ca 2 SiO 4 polymorphs. By decoding the interplay between core dislocation energies, core structures, and nucleation rate of reactivity, we find that γ-C2S and α-C2S polymorphs are the most favorable polymorphs for dislocations in Ca 2 SiO 4 , mainly due to their large pore channels which take away majority of the distortions imposed by edge dislocations. Furthermore, in the context of edge dislocation, while α-C2S represents the most active polymorph for reactivity and crystal growth, β-C2S represents the most brittle polymorph suitable for grinding. This work is the first report on the atomistic-scale analysis of edge dislocation-mediated properties of Ca 2 SiO 4 and may open up new opportunities for tuning fracture and reactivity processes of Ca 2 SiO 4 and other cement components.

Disclinations, dislocations, and continuous defects: A reappraisal

Science.gov (United States)

Kleman, M.; Friedel, J.

2008-01-01

Disclinations were first observed in mesomorphic phases. They were later found relevant to a number of ill-ordered condensed-matter media involving continuous symmetries or frustrated order. Disclinations also appear in polycrystals at the edges of grain boundaries; but they are of limited interest in solid single crystals, where they can move only by diffusion climb and, owing to their large elastic stresses, mostly appear in close pairs of opposite signs. The relaxation mechanisms associated with a disclination in its creation, motion, and change of shape involve an interplay with continuous or quantized dislocations and/or continuous disclinations. These are attached to the disclinations or are akin to Nye’s dislocation densities, which are particularly well suited for consideration here. The notion of an extended Volterra process is introduced, which takes these relaxation processes into account and covers different situations where this interplay takes place. These concepts are illustrated by a variety of applications in amorphous solids, mesomorphic phases, and frustrated media in their curved habit space. These often involve disclination networks with specific node conditions. The powerful topological theory of line defects considers only defects stable against any change of boundary conditions or relaxation processes compatible with the structure considered. It can be seen as a simplified case of the approach considered here, particularly suited for media of high plasticity or/and complex structures. It cannot analyze the dynamical properties of defects nor the elastic constants involved in their static properties; topological stability cannot guarantee energetic stability, and sometimes cannot distinguish finer details of the structure of defects.

Dislocation of primary total hip arthroplasty and the risk of redislocation.

LENUS (Irish Health Repository)

Brennan, Stephen A

2012-09-01

6554 primary total hip arthroplasties were reviewed. Risk factors for dislocation were analysed to assess which were important in terms of predicting recurrent instability. The patients risk of having a second dislocation was independently associated with the surgical approach adopted (p = 0.03) and the time to first dislocation from the primary hip replacement (p = 0.002). Early dislocators whose surgery was performed through an anterolateral approach had less recurrence than late dislocators through a posterior or transtrochanteric approach. None of the other risk factors including head size (p = 0.59), modularity (p = 0.54), mechanism of dislocation (p = 0.23), leg length discrepancy (p = 0.69) and acetabular inclination (p = 0.31) were influential. The use of an abduction brace was not useful in preventing a further dislocation with 69.2% of those braced re-dislocating compared to 68.5% who were not braced (p = 0.96).

The modified tibial tubercle osteotomy for anterior knee pain due to chondromalacia patellae in adults

Science.gov (United States)

Jack, C. M.; Rajaratnam, S. S.; Khan, H. O.; Keast-Butler, O.; Butler-Manuel, P. A.; Heatley, F. W.

2012-01-01

Objectives To assess the effectiveness of a modified tibial tubercle osteotomy as a treatment for arthroscopically diagnosed chondromalacia patellae. Methods A total of 47 consecutive patients (51 knees) with arthroscopically proven chondromalacia, who had failed conservative management, underwent a modified Fulkerson tibial tubercle osteotomy. The mean age was 34.4 years (19.6 to 52.2). Pre-operatively, none of the patients exhibited signs of patellar maltracking or instability in association with their anterior knee pain. The minimum follow-up for the study was five years (mean 72.6 months (62 to 118)), with only one patient lost to follow-up. Results A total of 50 knees were reviewed. At final follow-up, the Kujala knee score improved from 39.2 (12 to 63) pre-operatively to 57.7 (16 to 89) post-operatively (p chondromalacia. Six patients required screw removal. There were no major complications. Conclusions We conclude that this modification of the Fulkerson procedure is a safe and useful operation to treat anterior knee pain in well aligned patellofemoral joints due to chondromalacia patellae in adults, when conservative measures have failed. PMID:23610687

Key scattering mechanisms limiting the lateral transport in a modulation-doped polar heterojunction

Energy Technology Data Exchange (ETDEWEB)

Tien, Nguyen Thanh, E-mail: nttien@ctu.edu.vn; Thao, Pham Thi Bich [College of Natural Sciences, Can Tho University, 3-2 Road, Can Tho City (Viet Nam); Thao, Dinh Nhu [Center for Theoretical and Computational Physics, College of Education, Hue University, 34 Le Loi Street, Hue City (Viet Nam); Quang, Doan Nhat [Institute of Physics, Vietnamese Academy of Science and Technology, 10 Dao Tan Street, Hanoi (Viet Nam)

2016-06-07

We present a study of the lateral transport of a two-dimensional electron gas (2DEG) in a modulation-doped polar heterojunction (HJ). In contrast to previous studies, we assume that the Coulomb correlation among ionized impurities and among charged dislocations in the HJ is so strong that the 2DEG low-temperature mobility is not limited by impurity and dislocation scattering. The mobility, however, is specified by alloy disorder scattering and combined roughness scattering, which is the total effect induced by both the potential barrier and polarization roughness. The obtained results show that the alloy disorder and combined roughness scattering strongly depend on the alloy content and on the near-interface electron distribution. Our theory is capable of explaining the bell-shaped dependence of the lateral mobility on alloy content observed in AlGaN/GaN and on 2DEG density observed in AlN/GaN, which have not previously been explained.

Palliative surgery for acetabular metastasis with pathological central dislocation of the hip joint after radiation therapy. A case report

International Nuclear Information System (INIS)

Hoshi, Manabu; Takada, Jun; Oebisu, Naoto; Nakamura, Hiroaki; Taguchi, Susumu; Takami, Masatsugu

2012-01-01

Orthopedic surgery for bone metastases is mainly a palliative treatment. Pathological central dislocation of the hip joint secondary to osteonecrosis of acetabular metastasis after radiation therapy brings severe suffering to cancer patients. We performed minimally invasive palliative surgery for an elderly woman, and excellent pain relief was achieved. An 80-year-old female suffering from right hip pain was referred to our hospital. She had undergone surgery for lung cancer 5 years previously and her right acetabulum was subsequently affected by metastasis. With the aim of controlling the metastasis, radiation therapy was performed. Two years later, pathological central dislocation of the hip joint occurred with sudden onset of severe pain, and she was unable to maintain a sitting position and became bedridden. After she was referred to our hospital, we created an intentional pseudarthrosis in the femoral neck for palliation. After the surgery, excellent pain relief and remarkably improved mobility were achieved during her limited remaining lifetime. In this report, we introduce a novel method of producing a pseudarthrosis in the femoral neck for pathological dislocation. This procedure is a minimally invasive treatment and an alternative option for palliative surgery for pathological dislocation of the hip joint due to osteonecrosis after radiation therapy. (author)

Evaluation of the relationship between T1ρ and T2 values and patella cartilage degeneration in patients of the same age group

International Nuclear Information System (INIS)

Nishioka, Hiroaki; Hirose, Jun; Okamoto, Nobukazu; Okada, Tatsuya; Oka, Kiyoshi; Taniwaki, Takuya; Nakamura, Eiichi; Yamashita, Yasuyuki; Mizuta, Hiroshi

2015-01-01

Highlights: •This prospective cohort study investigated the association between the T1ρ and T2 values and the progression of cartilage degeneration in patients of the same age group. In this study, to the best of our knowledge, this is the first report to compare the T1ρ and T2 values between normal and OA knees within the same age group and to further investigate the relationship between the degree of cartilage degeneration and the T1ρ and T2 values in OA-grading groups of the same age. Our study confirmed that T1ρ and T2 mapping can be used to quantitatively evaluate the degree of patella cartilage degeneration in patients within the same age group.. -- Abstract: Objective: The aim of this study was to investigate the association between the T1ρ and T2 values and the progression of cartilage degeneration in patients of the same age group. Materials and methods: Sagittal T1ρ and T2 mapping and three-dimensional (3D) gradient-echo images were obtained from 78 subjects with medial knee osteoarthritis (OA). The degree of patella cartilage degeneration was classified into four groups using MRI-based grading: apparently normal cartilage, mild OA, moderate OA, and severe OA group. We measured the T1ρ and T2 values (ms) in the regions of interest set on the full-thickness patella cartilage. Then, we analyzed the relationship between the T1ρ and T2 values and the degree of patella cartilage degeneration. Results: There were no significant differences in age among the four groups. Both the T1ρ and T2 values showed a positive correlation with the degree of OA progression (ρ = 0.737 and ρ = 0.632, respectively). By comparison between the apparently normal cartilage and the mild OA groups, there were significant differences in the T1ρ mapping, but not in the T2 mapping. Conclusions: Our study confirmed that T1ρ and T2 mapping can quantitatively evaluate the degree of patella cartilage degeneration in patients within the same age group

Evaluation of the relationship between T1ρ and T2 values and patella cartilage degeneration in patients of the same age group

Energy Technology Data Exchange (ETDEWEB)

Nishioka, Hiroaki, E-mail: kinuhnishiok@fc.kuh.kumamoto-u.ac.jp [Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556 (Japan); Hirose, Jun; Okamoto, Nobukazu; Okada, Tatsuya; Oka, Kiyoshi; Taniwaki, Takuya; Nakamura, Eiichi [Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556 (Japan); Yamashita, Yasuyuki [Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556 (Japan); Mizuta, Hiroshi [Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto 860-8556 (Japan)

2015-03-15

Highlights: •This prospective cohort study investigated the association between the T1ρ and T2 values and the progression of cartilage degeneration in patients of the same age group. In this study, to the best of our knowledge, this is the first report to compare the T1ρ and T2 values between normal and OA knees within the same age group and to further investigate the relationship between the degree of cartilage degeneration and the T1ρ and T2 values in OA-grading groups of the same age. Our study confirmed that T1ρ and T2 mapping can be used to quantitatively evaluate the degree of patella cartilage degeneration in patients within the same age group.. -- Abstract: Objective: The aim of this study was to investigate the association between the T1ρ and T2 values and the progression of cartilage degeneration in patients of the same age group. Materials and methods: Sagittal T1ρ and T2 mapping and three-dimensional (3D) gradient-echo images were obtained from 78 subjects with medial knee osteoarthritis (OA). The degree of patella cartilage degeneration was classified into four groups using MRI-based grading: apparently normal cartilage, mild OA, moderate OA, and severe OA group. We measured the T1ρ and T2 values (ms) in the regions of interest set on the full-thickness patella cartilage. Then, we analyzed the relationship between the T1ρ and T2 values and the degree of patella cartilage degeneration. Results: There were no significant differences in age among the four groups. Both the T1ρ and T2 values showed a positive correlation with the degree of OA progression (ρ = 0.737 and ρ = 0.632, respectively). By comparison between the apparently normal cartilage and the mild OA groups, there were significant differences in the T1ρ mapping, but not in the T2 mapping. Conclusions: Our study confirmed that T1ρ and T2 mapping can quantitatively evaluate the degree of patella cartilage degeneration in patients within the same age group.

Inhibition of dye-coupling in Patella (mollusca) embryos by microinjection of antiserum against Nephrops (arthropoda) gap junctions

NARCIS (Netherlands)

Serras, F.; Buultjens, T.E.J.; Finbow, M.E.

1988-01-01

Antiserum raised against Nephrops gap junctions was injected into single cells of the 2-, 4-, 8-, 16-, and 32-cell stage of the Patella vulgata embryos. The pattern of junctional communication by iontophoresis of Lucifer Yellow CH was tested at the 32-cell stage. The results show that the normal

Interstitial impurity interactions and dislocation microdynamics in Mo crystals

International Nuclear Information System (INIS)

Kwok, D.N.

1975-05-01

The effects of interstitial impurities on the mechanical properties of molybdenum are explored by comparing results obtained for crystals of various interstitial contents controlled by ultra-high vacuum outgassing. Results show a modulus reduction for as-grown samples and for outgassed specimens at low applied stresses. As a function of plastic microstrain, the values of modulus defect for both as-grown and outgassed specimens saturate at the same value. Interstitial impurities act as pinning agents to dislocation bowing, but when all the easy dislocation loops have broken away from local interstitial pins, the modulus defect reaches a constant saturation value. Etch pitting techniques were used to correlate microstrain observations with dislocation generation and motion. It has been found that edge dislocation generation and movement are active in the microstrain region while screw dislocations are relatively inactive until the macrostrain region is reached. Dislocation velocities range from 10 -6 to 10 -3 cm/s and the average distance between interstitial impurity pinning points is found to be approximately 8 x 10 -4 cm. (U.S.)

On damping of screw dislocation bending vibrations in dissipative crystal: limiting cases

Science.gov (United States)

Dezhin, V. V.

2018-03-01

The expression for the generalized susceptibility of the dislocation obtained earlier was used. The electronic drag mechanism of dislocations is considered. The study of small dislocation oscillations was limited. The contribution of the attenuation of low-frequency bending screw dislocation vibrations to the overall coefficient of dynamic dislocation drag in the long-wave and short-wave limits is calculated. The damping of short-wave bending screw dislocation vibrations caused by an external action of an arbitrary frequency has been investigated. The contribution of long-wave bending screw dislocation vibrations damping in the total drag coefficient at an arbitrary frequency is found.

Bilateral Posterior Tibial Tendon and Flexor Digitorum Longus Dislocations.

Science.gov (United States)

Padegimas, Eric M; Beck, David M; Pedowitz, David I

2017-04-01

The authors present a case of a previously healthy and athletic 17-year-old female who presented with a 3.5-year history of medial left ankle pain after sustaining an inversion injury while playing basketball. Prior to presentation, she had failed prior immobilization and physical therapy for a presumed ankles sprain. Physical examination revealed a dislocated posterior tibial tendon (PTT) that was temporarily reducible, but would spontaneously dislocate immediately after reduction. She had pain and snapping of the PTT with resisted ankle plantar flexion and resisted inversion as well as 4/5 strength in ankle inversion. The diagnosis of dislocated PTT was confirmed on magnetic resonance imaging (MRI). The patient underwent suture anchor repair of the medial retinaculum of the left ankle. At the time of surgery both the PTT and flexor digitorum longus (FDL) were dislocated. Three months postoperatively, the patient represented with PTT dislocation of the right (nonoperative) ankle confirmed by MRI. After failure of immobilization, physical therapy, and oral anti-inflammatory medications, the patient underwent suture anchor repair of the medial retinaculum of the right ankle. At 6 months postoperatively, the patient has 5/5 strength inversion bilaterally, no subluxation of either PTT, and has returned to all activities without limitation. The authors present this unique case of bilateral PTT dislocation and concurrent PTT/FDL dislocation along with review of the literature for PTT dislocation. The authors highlight the common misdaiganosis of this injury and highlight the successful results of surgical intervention. Level V: Case report.

Energetics of dislocation transformations in hcp metals

International Nuclear Information System (INIS)

Wu, Zhaoxuan; Yin, Binglun; Curtin, W.A.

2016-01-01

Dislocation core structures of hcp metals are highly complex and differ significantly among the hcp family. Some dislocations undergo unconventional transformations that have significant effects on the material plastic flow. Here, the energetics of dislocation dissociations are analyzed in a general anisotropic linear elastic theory framework for transformations in which changes in the partial Burgers vectors are small. Quantitative analyses on various transformations are made using DFT-computed stacking fault energies and partial Burgers vectors. Specifically, possible transformations of the mixed, edge, and screw 〈c+a〉 and screw 〈a〉 dislocations in 6 hcp metals (Mg, Ti, Zr, Re, Zn, Cd) are studied. Climb dissociation of mixed or edge 〈c+a〉 dislocations to the Basal plane is energetically favorable in all 6 metals and thus only limited by thermal activation. The 〈c+a〉 screw dislocation is energetically preferable on Pyramidal I for Ti, Zr, and Re, and on Pyramidal II for Zn and Cd. In Mg, the energy difference between screw 〈c+a〉 on Pyramidal I and II planes is small, suggesting relatively easy cross-slip. For the screw 〈a〉, Basal dissociation is energetically favorable in Mg, Re, Zn and Cd, while Prism dissociation is strongly favorable in Ti and Zr. Only Ti, Zr and Re show a metastable state for dissociation on the Prism plane, and the energy difference between screw 〈a〉 on the Prism and Pyramidal I planes is relatively small in all systems, suggesting relatively easy cross-slip of 〈a〉 in Ti and Zr. The elastic analysis thus provides a single framework able to capture the controlling energetics for different dissociations and slip systems in hcp metals. When the calculated energy differences are very small, the results point to the need for detailed modeling of the atomistic core structure. Moreover, the analyses rationalize broad experimental observations on dominant slip systems and dislocation behaviours, and provide

A parallel algorithm for 3D dislocation dynamics

International Nuclear Information System (INIS)

Wang Zhiqiang; Ghoniem, Nasr; Swaminarayan, Sriram; LeSar, Richard

2006-01-01

Dislocation dynamics (DD), a discrete dynamic simulation method in which dislocations are the fundamental entities, is a powerful tool for investigation of plasticity, deformation and fracture of materials at the micron length scale. However, severe computational difficulties arising from complex, long-range interactions between these curvilinear line defects limit the application of DD in the study of large-scale plastic deformation. We present here the development of a parallel algorithm for accelerated computer simulations of DD. By representing dislocations as a 3D set of dislocation particles, we show here that the problem of an interacting ensemble of dislocations can be converted to a problem of a particle ensemble, interacting with a long-range force field. A grid using binary space partitioning is constructed to keep track of node connectivity across domains. We demonstrate the computational efficiency of the parallel micro-plasticity code and discuss how O(N) methods map naturally onto the parallel data structure. Finally, we present results from applications of the parallel code to deformation in single crystal fcc metals

Increasing lateral tibial slope: is there an association with articular cartilage changes in the knee?

Energy Technology Data Exchange (ETDEWEB)

Khan, Nasir; Shepel, Michael; Leswick, David A.; Obaid, Haron [University of Saskatchewan, Department of Medical Imaging, Royal University Hospital, and College of Medicine, Saskatoon, Saskatchewan (Canada)

2014-04-15

The geometry of the lateral tibial slope (LTS) plays an important role in the overall biomechanics of the knee. Through this study, we aim to assess the impact of LTS on cartilage degeneration in the knee. A retrospective analysis of 93 knee MRI scans (1.5 T or 3 T) for patients aged 20-45 years with no history of trauma or knee surgery, and absence of internal derangement. The LTS was calculated using the circle method. Chondropathy was graded from 0 (normal) to 3 (severe). Linear regression analysis was used for statistical analysis (p < 0.05). In our cohort of patients, a statistically significant association was seen between increasing LTS and worsening cartilage degenerative changes in the medial patellar articular surface and the lateral tibial articular surface (p < 0.05). There was no statistically significant association between increasing LTS and worsening chondropathy of the lateral patellar, medial trochlea, lateral trochlea, medial femoral, lateral femoral, and medial tibial articular surfaces. Our results show a statistically significant association between increasing LTS and worsening cartilage degenerative changes in the medial patella and the lateral tibial plateau. We speculate that increased LTS may result in increased femoral glide over the lateral tibial plateau with subsequent increased external rotation of the femur predisposing to patellofemoral articular changes. Future arthroscopic studies are needed to further confirm our findings. (orig.)

Increasing lateral tibial slope: is there an association with articular cartilage changes in the knee?

International Nuclear Information System (INIS)

Khan, Nasir; Shepel, Michael; Leswick, David A.; Obaid, Haron

2014-01-01

The geometry of the lateral tibial slope (LTS) plays an important role in the overall biomechanics of the knee. Through this study, we aim to assess the impact of LTS on cartilage degeneration in the knee. A retrospective analysis of 93 knee MRI scans (1.5 T or 3 T) for patients aged 20-45 years with no history of trauma or knee surgery, and absence of internal derangement. The LTS was calculated using the circle method. Chondropathy was graded from 0 (normal) to 3 (severe). Linear regression analysis was used for statistical analysis (p < 0.05). In our cohort of patients, a statistically significant association was seen between increasing LTS and worsening cartilage degenerative changes in the medial patellar articular surface and the lateral tibial articular surface (p < 0.05). There was no statistically significant association between increasing LTS and worsening chondropathy of the lateral patellar, medial trochlea, lateral trochlea, medial femoral, lateral femoral, and medial tibial articular surfaces. Our results show a statistically significant association between increasing LTS and worsening cartilage degenerative changes in the medial patella and the lateral tibial plateau. We speculate that increased LTS may result in increased femoral glide over the lateral tibial plateau with subsequent increased external rotation of the femur predisposing to patellofemoral articular changes. Future arthroscopic studies are needed to further confirm our findings. (orig.)

MR-specific staging of chondromalacia patellae using a special knee compressor: Comparison with arthroscopic findings. MRT-spezifische Einteilung der Chondromalacia patellae unter Zuhilfenahme eines speziellen Kniekompressors: Gegenueberstellung mit dem arthroskopischen Befund

Energy Technology Data Exchange (ETDEWEB)

Andresen, R. (Klinik fuer Radiologie, Abt. Radiologische Diagnostik, Universitaetsklinik Steglitz, FU Berlin (Germany)); Radmer, S. (Orthopaedisches Fachinst., Berlin (Germany)); Koenig, H. (Klinik fuer Radiologie, Abt. Radiologische Diagnostik, Universitaetsklinik Steglitz, FU Berlin (Germany)); Wolf, K.J. (Klinik fuer Radiologie, Abt. Radiologische Diagnostik, Universitaetsklinik Steglitz, FU Berlin (Germany))

1993-12-01

The present study proposes a new MRI-specific staging of chondromalacia patellae (CMP) which is based on cartilage thickness decrease and signal intensity behaviour under compression as well as cartilage morphology in the plain image. The investigation was performed in 30 patients with varying knee complaints who underwent arthroscopy after MR imaging. It was demonstrated that three CMP stages can already be differentiated by MRI under compression in arthroscopically healthy cartilage. This proves a marked improvement in the early diagnosis of CMP. (orig.)

Management of primary anterior shoulder dislocations using immobilization.

Science.gov (United States)

Smith, Brent I; Bliven, Kellie C Huxel; Morway, Genoveffa R; Hurbanek, Jason G

2015-05-01

Reference/Citation : Paterson WH, Throckmorton TW, Koester M, Azar FM, Kuhn JE. Position and duration of immobilization after primary anterior shoulder dislocation: a systemic review and meta-analysis of the literature. J Bone Joint Surg Am. 2010;92(18):2924-2933. Does an optimum duration and position of immobilization after primary anterior shoulder dislocation exist for reducing recurrence rates? MEDLINE/PubMed, EMBASE, and Cochrane databases were searched up to December 2009 without limitations. The search terms for all databases used were shoulder AND dislocation and shoulder AND immobilization. Criteria used to include articles were (1) English language, (2) prospective level I or level II studies (according to Journal of Bone & Joint Surgery guidelines), (3) nonoperative management of initial anterior shoulder dislocation, (4) minimum follow-up of 1 year, and (5) rate of recurrent dislocation as a reported outcome. A standardized evaluation method was used to extract data to allow assessment of methods issues and statistical analysis to determine sources of bias. The primary outcome was the recurrence rate after nonoperative management of anterior shoulder dislocation. Additional data extracted and used in subanalyses included duration and position of immobilization and age at the time of initial dislocation. Data were analyzed to determine associations among groups using 2-tailed Fisher exact tests. For pooled categorical data, relative risk of recurrent dislocation, 95% confidence intervals, and heterogeneity using the I(2) statistic and χ(2) tests were calculated for individual studies. The Mantel-Haenszel method was used to combine studies and estimate overall relative risk of recurrent dislocation and 95% confidence intervals. The statistical difference between duration of immobilization and position was determined using z tests for overall effect. Pooled results were presented as forest plots. In the initial search of the databases, the authors

Effect of dislocations on superconductivity. O vliyanii dislokatsiy na sverkhrpovodimost'

Energy Technology Data Exchange (ETDEWEB)

Agap' ev, B D; Bytsenko, A A; Sukhanov, S A

1976-01-01

Electron-dislocation interaction is analyzed here. The effect of dislocations on the superconductor characteristics is determined according to the Ginzburg-Landau method. Appreciable changes in the stability of the superconductive state are found to occur in the vicinity of dislocations.

A three dimensional discrete dislocation dynamics modelling of the early cycles of fatigue in an austenitic stainless steel 316L: dislocation microstructure and damage analysis

International Nuclear Information System (INIS)

Depres, Ch.

2005-01-01

A numerical code modelling the collective behaviour of dislocations at a mesoscopic scale (Discrete Dislocation Dynamics code) is used to analyse the cyclic plasticity that occurs in surface grains of an AISI 316L stainless steel, in order to understand the plastic mechanism involved in crack initiation in fatigue. Firstly, the analyses of both the formation and the evolution of the dislocation microstructures show the crucial role of cross-slip played in the strain localization in the form of slip bands. As the cycling proceeds, the slip bands exhibit well-organized dislocation arrangements that substitute to dislocation tangles, involving specific interaction mechanisms between primary and deviate systems. Secondly, both the surface displacements generated by plastic slip and the distortion energy induced by the dislocation microstructure have been analysed. We find that an irreversible surface relief in the form of extrusion/intrusion can be induced by cyclic slip of dislocations. The number of cycles for the crack initiation follows a Manson-Coffin type law. The analyses of the concentration of the distortion energy and its repartition in the slip bands show that beneficial energetic zones may be present at the very beginning of the cycling, and that mode-II crack propagation in the surface grains results from a succession of micro-crack initiations along primary slip plane, which is facilitated by various effects (stress concentration due to surface relief, environment effects...). Finally, a dislocation-based model for cyclic plasticity is proposed from Discrete Dislocation Dynamics results. (author)

Dislocation dynamics modelling of radiation damage in thin films

International Nuclear Information System (INIS)

Ferroni, Francesco; Tarleton, Edmund; Fitzgerald, Steven

2014-01-01

Transmission electron microscopy is a key tool for the extraction of information on radiation damage, the understanding of which is critical for materials development for nuclear fusion and fission reactors. Dislocations in TEM samples are subject to strong image forces, owing to the nanometric sample thicknesses, which may introduce artifacts in the damage analysis. Using dislocation dynamics, we elucidate the roles played by dislocation–surface interactions, dislocation–dislocation interactions and self-interactions due to climb for loop types observed in TEM. Comparisons with analytic solutions for a dislocation loop and an edge dislocation in a half-space are included, and the relationship between glide force and loop tilt examined. The parameters for convergence of the zero-traction boundary conditions are obtained, after which the evolution of dislocation structures in a thin film is studied. It is found that three main length scales govern the physical processes: the image force is governed by the distance of the loop from the surface and scales with the film thickness; the glide force is governed by the image stress as well as the loop–loop interaction stress which is in turn governed by the loop spacing L∼1/√ρ, where ρ is the loop density; finally, the climb force depends on the loop size. The three forces compete and their relative magnitudes define the evolution pathway of the dislocation structure. (paper)

Discuss the cause and treatment of pacemaker lead dislocation and deal with

International Nuclear Information System (INIS)

Chen Yueguang; Zhang Dadong; Lu Jie; Yang Hui; Liu Chunyan; Zhang Wei

2003-01-01

Objective: To follow up the patients with pacemaker, observe the condition of pacemaker lead, to explore the cause of lead dislocation, to find out and prevent its occurrence. Methods: Summarizing the clinical data of 6 patients with pacemaker, 7 pacemaker leads with 8 time dislocation, pacemaker 2 DDDR, 2 DDD, 2 VVI. Results: Four patients were punctured from right subclavian vein, one from left subclavian vein and one from right brachiocephalic vein; four leads were dislocation in atrium and one mildly dislocation; four leads dislocation in ventricle and two mildly dislocation; There were 3 old women with 4 leads and 5 times of dislocation

Ipsilateral Fracture Shaft Femur with Neglected Dislocation of Prosthesis: A Case Report

Directory of Open Access Journals (Sweden)

Mantu Jain

2013-10-01

Full Text Available Introduction: Neglected hip dislocation is rare in today’s world and after prosthesis replacement even rarer finding. However such patients may not report to surgeons until they develop secondary complications. Management of such patient’s is a challenge to the treating surgeon and need to be tailored suiting to patient’s demands, expectations and constraints of financial resources. We did not find a similar case in the electronic and print media and therefore report this case which was innovatively managed. Case Report: A 60 year farmer presented with fracture shaft femur and ipsilateral dislocation prosthesis of right hip. He had a hemiarthroplasty done for fracture neck of femur in the past but used to walk with a lurch since he started to ambulate after discharge. However he was satisfied despite “some problems” which had caused shortening of his limb. The patient was informed of the various treatment options and their possible complications. He expressed his inability to afford a Total Hip Arthroplasty (THA at any stage and consented for other options discussed with him. The patient was positioned supine and adductor tenotomy done. Next he was positioned laterally and the fracture was fixed with heavy duty broad dynamic compression plate and screws. The wound was temporarily closed. Now through the previous scar via posterior approach the hip was exposed. The prosthesis was found to be firmly fixed to the proximal femur. The acetabulum was cleared with fibrous tissue. All attempts the prosthesis to relocate the prosthesis failed after several attempts and it was best decided to leave alone. Post operatively period was uneventful. At follow up he refused for any further manoeuvre in future inform of heavy traction and attempts to reduce the same. At one year when he was walking unaided and his X-rays showed that fracture had well united his SF-36 score was PCS – 49.6 and MCS – 51.9. Conclusion: Ipsilateral shaft femur fracture

Dislocations and radiation damage in {alpha}-uranium; Dislocations et effets des radiations dans l'uranium {alpha}

Energy Technology Data Exchange (ETDEWEB)

Leteurtre, J [Commissariat a l' Energie Atomique, 92 - Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

1968-07-01

Dislocations in {alpha}-uranium were studied by electron microscopy. Electropolishing of thin foils was performed at low temperature (-110 deg. C) to prevent oxidation. Burgers vectors of twins dislocations are defined. Interactions between slip and twinning are studied from both experimental and theoretical point of view. Samples irradiated at several burn-up were examined. In order to explain our micrographic results, and also all information gathered in literature about radiation damage in {alpha}-uranium, a coherent model is propound for the fission particles effects. We analyse the influences of parameters: temperature, dislocation density, impurity content. The number of point defects created by one initial fission is determined for pure and annealed metal. The importance of the self-anneal which occurs immediately in each displacement spike, and the anneal due to a new fission on the damage resulting from a previous fission, are estimated. The focussing distance in [100] direction is found to be about 1000 Angstrom, at 4 deg. K. (author) [French] Ce travail est une etude par microscopie electronique des dislocations induites dans l'uranium {alpha}, soit par deformation plastique, soit par irradiation. Une methode de preparation des lames minces a basse temperature (-110 deg. C) a ete mise au point. Les vecteurs de Burgers des diverses dislocations de macles de ce metal ont ete definis. Les interactions glissements- maclages sont etudiees experimentalement et theoriquement. Des echantillons irradies a divers taux de combustion ont ete examines. Pour expliquer nos resultats micrographiques, et aussi l'ensemble des informations recueillies dans la litterature concernant l'endommagement par irradiation de l'uranium-{alpha}, nous proposons un modele coherent de l'effet des fragments de fission dans ce metal. L'influence des parametres: temperature, densite de dislocations, impuretes est analysee. Le nombre de defauts ponctuels crees par une fission dans du metal

Growth and instability of charged dislocation loops under irradiation in ceramic materials

CERN Document Server

Ryazanov, A I; Kinoshita, C; Klaptsov, A V

2002-01-01

We have investigated the physical mechanisms of the growth and stability of charged dislocation loops in ceramic materials with very strong different mass of atoms (stabilized cubic zirconia) under different energies and types of irradiation conditions: 100-1000 keV electrons, 100 keV He sup + and 300 keV O sup + ions. The anomalous formation of extended defect clusters (charged dislocation loops) has been observed by TEM under electron irradiation subsequent to ion irradiation. It is demonstrated that very strong strain field (contrast) near charged dislocation loops is formed. The dislocation loops grow up to a critical size and after then become unstable. The instability of the charged dislocation loop leads to the multiplication of dislocation loops and the formation of dislocation network near the charged dislocation loops. A theoretical model is suggested for the explanation of the growth and stability of the charged dislocation loop, taking the charge state of point defects. The calculated distribution...

Hip dysplasia and congenital hip dislocation

Energy Technology Data Exchange (ETDEWEB)

Lingg, G.; Nebel, G.; von Torklus, D.

1981-11-01

In human genetics and orthopedics quite different answers have been given to the question of hereditary transmission and frequency of hip dysplasia in families of children with congenital hip dislocation. We therefore have made roentgenometric measurements of 110 parents of children with congenital hip dislocation. In 25% we found abnormal flat acetabulae, whereas 12% had pathologic deep hips. This may propose a new concept of morphology of congenital hip dysplasia.

Plain film diagnostic of the acromio-clavicular dislocation

International Nuclear Information System (INIS)

Vogel, H.; Thomae, J.; Jungbluth, K.H.; Hamburg Univ.

1980-01-01

The distance between the clavicula and the acromion, between the clavicula and the processus coracoideus and the step height between the acromion and the clavicula arch were measured on roentgen films. Evaluated were plain films of the shoulder and of the chest. 64 patients with dislocation of the acromio-clavicular joint were compared to patients without shoulder lesion. The comparance of both groups showed that measures exceeding the upper limits of the group without lesions are highly suggestive for acromio-clavicular dislocation. If one defines an acromio-clavicular dislocation as proved when two of the measured three distances exceed the upper limit, then an acromio-clavicular dislocation could be seen in 36% of the analysed cases on plain films of the shoulder and in 56% on plain chest films. (orig.) [de

Dislocations in AlGaN: Core Structure, Atom Segregation, and Optical Properties.

Science.gov (United States)

Massabuau, Fabien C-P; Rhode, Sneha L; Horton, Matthew K; O'Hanlon, Thomas J; Kovács, András; Zielinski, Marcin S; Kappers, Menno J; Dunin-Borkowski, Rafal E; Humphreys, Colin J; Oliver, Rachel A

2017-08-09

We conducted a comprehensive investigation of dislocations in Al 0.46 Ga 0.54 N. Using aberration-corrected scanning transmission electron microscopy and energy dispersive X-ray spectroscopy, the atomic structure and atom distribution at the dislocation core have been examined. We report that the core configuration of dislocations in AlGaN is consistent with that of other materials in the III-Nitride system. However, we observed that the dissociation of mixed-type dislocations is impeded by alloying GaN with AlN, which is confirmed by our experimental observation of Ga and Al atom segregation in the tensile and compressive parts of the dislocations, respectively. Investigation of the optical properties of the dislocations shows that the atom segregation at dislocations has no significant effect on the intensity recorded by cathodoluminescence in the vicinity of the dislocations. These results are in contrast with the case of dislocations in In 0.09 Ga 0.91 N where segregation of In and Ga atoms also occurs but results in carrier localization limiting non-radiative recombination at the dislocation. This study therefore sheds light on why InGaN-based devices are generally more resilient to dislocations than their AlGaN-based counterparts.

Condylar Joint Fusion and Stabilization (by Screws and Plates) in Nontraumatic Atlanto-Occipital Dislocation: Technical Report of 2 Cases.

Science.gov (United States)

Chowdhury, Forhad H; Haque, Mohammod Raziul; Alam, Sarwar Murshed; Khaled Chowdhury, S M Noman; Khan, Shamsul Islam; Goel, Atul

2017-11-01

Nontraumatic spontaneous atlanto-occipital dislocation (AOD) is rare. In this report, we discuss the technical steps of condylar joint fusion and stabilization (by screws and plates) in nontraumatic AOD. To the best of our knowledge, it is the first report of such techniques. A young girl and a young man with progressive quadriparesis due to nontraumatic spontaneous atlanto-occipital dislocation were managed by microsurgical reduction, fusion, and stabilization of the joint by occipital condylar and C1 lateral mass screw and plate fixation after mobilization of vertebral artery. In both cases, condylar joints fixation and fusion were done successfully. Condylar joint stabilization and fusion may be a good or alternative option for AOD. Copyright © 2017 Elsevier Inc. All rights reserved.

Interobserver and intraobserver reliability of radiographic classification of acromioclavicular joint dislocations.

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Ringenberg, Jonathan D; Foughty, Zachary; Hall, Adam D; Aldridge, J Mack; Wilson, Joseph B; Kuremsky, Marshall A

2018-03-01

The classification and treatment of acromioclavicular (AC) joint dislocations remain controversial. The purpose of this study was to determine the interobserver and intraobserver reliability of the Rockwood classification system. We hypothesized poor interobserver and intraobserver reliability, limiting the role of the Rockwood classification system in determining severity of AC joint dislocations and accurately guiding treatment decisions. We identified 200 patients with AC joint injuries using the International Classification of Diseases, Ninth Revision code 831.04. Fifty patients met inclusion criteria. Deidentified radiographs were compiled and presented to 6 fellowship-trained upper extremity orthopedic surgeons. The surgeons classified each patient into 1 of the 6 classification types described by Rockwood. A second review was performed several months later by 2 surgeons. A κ value was calculated to determine the interobserver and intraobserver reliability. The interobserver and intraobserver κ values were fair (κ = 0.278) and moderate (κ = 0.468), respectively. Interobserver results showed that 4 of the 50 radiographic images had a unanimous classification. Intraobserver results for the 2 surgeons showed that 18 of the 50 images were rated the same on second review by the first surgeon and 38 of the 50 images were rated the same on second review by the second surgeon. We found that the Rockwood classification system has limited interobserver and intraobserver reliability. We believe that unreliable classification may account for some of the inconsistent treatment outcomes among patients with similarly classified injuries. We suggest that a better classification system is needed to use radiographic imaging for diagnosis and treatment of AC joint dislocations. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Transmission electron microscopy in situ investigation of dislocation mobility in semiconductors

CERN Document Server

Vanderschaeve, G; Insa, P D T; Caillard, D

2000-01-01

TEM in situ straining experiments provide a unique way to investigate in real time the behaviour of individual dislocations under applied stress. The results obtained on a variety of semiconductors are presented: numerous dislocation sources are observed which makes it possible to measure the dislocation velocity as a function of different physical parameters (local shear stress, temperature, dislocation character, length of the moving dislocation, ...). The experimental results are consistent with a dislocation glide governed by the Peierls mechanism, even for II-VI compounds which have a significant degree of ionic character. For compounds, a linear dependence of the dislocation velocity on the length of the moving segment is noticed, whereas for elemental semiconductors a transition between a length-dependent and a length-independent velocity regime is observed. Analysed in the framework of the kink diffusion model (Hirth and Lothe theory), these results allow an estimation of the kink formation and migrat...

Vastus Medialis advancement: clinical results and correlation with tangential X-rays of the patellofemoral joint

International Nuclear Information System (INIS)

O'Beirne, J.; O'Connell, R.J.; White, M.

1986-01-01

Thirteen patients who had recurrent dislocation of the patella treated by vastus medialis advancement were reviewed, and tangential X-rays of the patellofemoral joint were taken at the time of review. Clinically the results were excellent or good in ten (77%). However, the X-ray appearances were similar to what would be expected in a group of patients with untreated recurrent dislocation, probably because the corrective action of the vastus medialis did not apply with the quadriceps relaxed for X-ray. We conclude that vastus medialis advancement is a successful operation for recurrent patellar dislocation but that tangential X-rays of the patellofemoral joint are not an indicator of the outcome of surgery. (author)

Dislocation kinetics and the acoustic-wave approximation for liquids

International Nuclear Information System (INIS)

Stout, R.B.

1983-03-01

A dislocation-dependent model for liquids describes the lattice deformation and the fluidity deformation as additive deformations. The lattice deformation represents distortions of an atom's potential energy structure and is a recoverable deformation response. The fluidity deformation represents discontinuous repositioning of atoms by dislocation kinetics in the lattice structure and is a nonrecoverable deformation response. From this model, one concludes that in liquids the acoustic-wave approximation is a description of a recoverable oscillation deformation that has dissipation because of dislocation kinetics. Other more-complex waves may exist, but such waves would rapidly disappear because of the small thermodynamic potential for dislocation kinetics in liquids

High-voltage electron-microscopical observation of crack-tip dislocations in silicon crystals

International Nuclear Information System (INIS)

Tanaka, Masaki; Higashida, Kenji

2005-01-01

Crack-tip dislocations in silicon single crystals were observed by high-voltage electron microscopy. Cracks were introduced into silicon wafers at room temperature by a Vickers indenter. The indented specimens were annealed at 823 K in order to activate dislocation emission from the crack tip under the residual stress due to the indentation. In the specimen without annealing, no dislocations were observed around the crack. On the other hand, in the specimen after the annealing, the aspect of the early stage of dislocation emission was observed, where dislocations were emitted not as a perfect dislocation but as a partial dislocation in the hinge-type plastic zone. Prominent dislocation arrays that were emitted from a crack tip were also observed, and they were found to be of shielding type, which increases the fracture toughness of those crystals

Computational issues in the simulation of two-dimensional discrete dislocation mechanics

Science.gov (United States)

Segurado, J.; LLorca, J.; Romero, I.

2007-06-01

The effect of the integration time step and the introduction of a cut-off velocity for the dislocation motion was analysed in discrete dislocation dynamics (DD) simulations of a single crystal microbeam. Two loading modes, bending and uniaxial tension, were examined. It was found that a longer integration time step led to a progressive increment of the oscillations in the numerical solution, which would eventually diverge. This problem could be corrected in the simulations carried out in bending by introducing a cut-off velocity for the dislocation motion. This strategy (long integration times and a cut-off velocity for the dislocation motion) did not recover, however, the solution computed with very short time steps in uniaxial tension: the dislocation density was overestimated and the dislocation patterns modified. The different response to the same numerical algorithm was explained in terms of the nature of the dislocations generated in each case: geometrically necessary in bending and statistically stored in tension. The evolution of the dislocation density in the former was controlled by the plastic curvature of the beam and was independent of the details of the simulations. On the contrary, the steady-state dislocation density in tension was determined by the balance between nucleation of dislocations and those which are annihilated or which exit the beam. Changes in the DD imposed by the cut-off velocity altered this equilibrium and the solution. These results point to the need for detailed analyses of the accuracy and stability of the dislocation dynamic simulations to ensure that the results obtained are not fundamentally affected by the numerical strategies used to solve this complex problem.

Evaluation of the mechanism and principles of management of temporomandibular joint dislocation. Systematic review of literature and a proposed new classification of temporomandibular joint dislocation.

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Akinbami, Babatunde O

2011-06-15

Virtually all the articles in literature addressed only a specific type of dislocation. The aim of this review was to project a comprehensive understanding of the pathologic processes and management of all types of dislodgement of the head of the mandibular condyle from its normal position in the glenoid fossa. In addition, a new classification of temporomandibular joint dislocation was also proposed. A thorough computer literature search was done using the Medline, Cochrane library and Embase database. Key words like temporo-mandibular joint dislocation were used for the search. Additional manual search was done by going through published home-based and foreign articles. Case reports/series, and original articles that documented the type of dislocation, number of cases treated in the series and original articles. Treatment done and outcome of treatment were included in the study. A total of 128 articles were reviewed out which 79 were found relevant. Of these, 26 were case reports, 17 were case series and 36 were original articles. 79 cases were acute dislocations, 35 cases were chronic protracted TMJ dislocations and 311 cases were chronic recurrent TMJ dislocations. Etiology was predominantly trauma in 60% of cases and other causes contributed about 40%. Of all the cases reviewed, only 4 were unilateral dislocation. Various treatment modalities are outlined in this report as indicated for each type of dislocation. The more complex and invasive method of treatment may not necessarily offer the best option and outcome of treatment, therefore conservative approaches should be exhausted and utilized appropriately before adopting the more invasive surgical techniques.

Dislocations and related defects in niobium oxide structures

Energy Technology Data Exchange (ETDEWEB)

Anderson, J S; Hutchinson, J L; Lincoln, F J [Oxford Univ. (UK). Inorganic Chemistry Lab.

1977-01-07

Lattice images of the niobium oxides, structures based on the linkage of octahedral groups in continuous networks, occasionally contain features recognizable as dislocations. Since lattice imaging enables the microstructure to be resolved in greater detail, at the level of local structural organization, it is possible to determine the configuration, and also to infer the chemical composition, of dislocated areas. By treating the niobium oxide 'block' structures as superstructures of the ReO/sub 3/ (DO/sub 9/) type, the topology of dislocations can be expressed by relations between the insertion (or deletion) of one or more half-planes of cations, or of oxygen atoms only, changes in the number of crystallographic shear plane interfaces between blocks or columns, changes in (idealized) dimensions and any requisite distortion in the third dimension. Mapping the structure around a dislocation, from the lattice image, is directly equivalent to plotting the Burgers' circuit. In this way, the precise nature of a dislocating perturbation and its implications for the local chemical composition of the crystal can be directly identified. The method is exemplified by analysis of dislocations and of related extended defects of several types, associated with twinning phenomena, semicoherent intergrowth between different ReO/sub 3/-type superstructures and arrays building up a low angle boundary. The essential features of the analysis are not restricted to structures of the niobium oxide type, but can be extended to other types of polyhedron networks.

Influence of Elastic Anisotropy on Extended Dislocation Nodes

Energy Technology Data Exchange (ETDEWEB)

Pettersson, B

1971-09-15

The interaction forces between the partial dislocations forming an extended dislocation node are calculated using elasticity theory for anisotropic media.s are carried out for nodes of screw, edge and mixed character in Ag, which has an anisotropy ratio A equal to 3, and in a hypothetic material with A = 1 and the same shear modulus as Ag. The results are compared with three previous theories using isotropic elasticity theory. As expected, in Ag the influence of anisotropy is of the same order as the uncertainty due to the dislocation core energy

Dislocation following total knee arthroplasty: A report of six cases

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Villanueva Manuel

2010-01-01

Full Text Available Background: Dislocation following total knee arthroplasty (TKA is the worst form of instability. The incidence is from 0.15 to 0.5%. We report six cases of TKA dislocation and analyze the patterns of dislocation and the factors related to each of them. Materials and Methods: Six patients with dislocation of knee following TKA are reported. The causes for the dislocations were an imbalance of the flexion gap (n=4, an inadequate selection of implants (n=1, malrotation of components (n=1 leading to incompetence of the extensor mechanism, or rupture of the medial collateral ligament (MCC. The patients presented complained of pain, giving way episodes, joint effusion and difficulty in climbing stairs. Five patients suffered posterior dislocation while one anterior dislocation. An urgent closed reduction of dislocation was performed under general anaesthesia in all patients. All patients were operated for residual instability by revision arthroplasty after a period of conservative treatment. Results: One patient had deep infection and knee was arthrodesed. Two patients have a minimal residual lag for active extension, including a patient with a previous patellectomy. Result was considered excellent or good in four cases and fair in one, without residual instability. Five out of six patients in our series had a cruciate retaining (CR TKA designs: four were revised to a posterior stabilized (PS TKA and one to a rotating hinge design because of the presence of a ruptured MCL. Conclusion: Further episodes of dislocation or instability will be prevented by identifying and treating major causes of instability. The increase in the level of constraint and correction of previous technical mistakes is mandatory.

Evaluation of CT in the investigation of patellofemoral malalignment

International Nuclear Information System (INIS)

Zhang Quan; Huang Huangyuan; Xia Jun; Chen Wenjun

1999-01-01

Objective: To evaluate CT in investigating patellofemoral malalignment. Methods: CT was used to evaluate 32 patients (50 knees) with persistent patellofemoral pain and 15 asymptomatic volunteers (20 knees). Multiple mid-patellar images were obtained at 30 degree flexion. Results: Compared to controls, the patients had marked malalignment including three distinct patterns. 11 knees had lateral patellae based on high congruence angles (CA). 8 knees had tilted patellae with lower lateral patellofemoral angles (LPFA). 10 knees had both high CA and lower LPFA indicating both lateral and tilted patella. Conclusions: CT may be the optimal imaging method of evaluating the patellofemoral joint. An awareness of different patterns of malalignment is a significant advantage of CT when planning selective surgical realignment for these patients

Jaw Dislocation as an Unusual Complication of Upper Endoscopy

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Evan S. Dellon

2016-05-01

Full Text Available This case report presents an unusual complication of upper endoscopy, resulting in jaw dislocation. Temporomandibular joint dislocation is commonly reported in association with anesthesia and intubation, but it is not widely recognized as a complication of gastrointestinal endoscopy. This report also reviews the current literature regarding this complication and discusses the potential causes of dislocation, differential diagnoses for jaw pain following endoscopy, and recommendations for prevention.