Posterior hip dislocation in a non-professional football player: a case report and review of the literature.

PubMed

Bakalakos, Matthaios; Benetos, Ioannis S; Rozis, Meletios; Vlamis, John; Pneumaticos, Spiros

2018-06-02

The majority of injuries during a football game are contusions, sprains and/or strains in the thigh, knee and ankle. Hip dislocations account for 2-5% of total hip dislocations, and they can be posterior or anterior. Major complications of traumatic hip dislocation include avascular necrosis of femoral head, secondary osteoarthritis, sciatic nerve injury and heterotopic ossification. On the occasion of a case of a 33-year-old football player, who suffered a posterior hip dislocation, associated with a posterior wall fracture of the acetabulum, while playing football, we review the literature and analyze the various mechanisms of injury, the possible complications and the management including surgery and rehabilitation.

Traumatic fracture-dislocation of the hip following rugby tackle: a case report.

PubMed

Venkatachalam, Santosh; Heidari, Nima; Greer, Tony

2009-12-15

Posterior fracture-dislocation of hip is uncommonly encountered in rugby injuries. We report such a case in an adult while playing rugby. The treating orthopaedician can be caught unaware and injuries in such sports can be potentially misdiagnosed as hip sprains. Immediate reduction of the dislocation was performed in theatres. The fracture was fixed with two lag screws and a neutralization plate. This led to early rehabilitation and speedy recovery with return to sporting activities by 12 months.

Unconstrained tripolar implants for primary total hip arthroplasty in patients at risk for dislocation.

PubMed

Guyen, Olivier; Pibarot, Vincent; Vaz, Gualter; Chevillotte, Christophe; Carret, Jean-Paul; Bejui-Hugues, Jacques

2007-09-01

We performed a retrospective study on 167 primary total hip arthroplasty (THA) procedures in 163 patients at high risk for instability to assess the reliability of unconstrained tripolar implants (press-fit outer metal shell articulating a bipolar polyethylene component) in preventing dislocations. Eighty-four percent of the patients had at least 2 risk factors for dislocation. The mean follow-up length was 40.2 months. No dislocation was observed. Harris hip scores improved significantly. Six hips were revised, and no aseptic loosening of the cup was observed. The tripolar implant was extremely successful in achieving stability. However, because of the current lack of data documenting polyethylene wear at additional bearing, the routine use of tripolar implants in primary THA is discouraged and should be considered at the present time only for selected patients at high risk for dislocation and with limited activities.

Traumatic fracture-dislocation of the hip following rugby tackle: a case report

PubMed Central

2009-01-01

Posterior fracture-dislocation of hip is uncommonly encountered in rugby injuries. We report such a case in an adult while playing rugby. The treating orthopaedician can be caught unaware and injuries in such sports can be potentially misdiagnosed as hip sprains. Immediate reduction of the dislocation was performed in theatres. The fracture was fixed with two lag screws and a neutralization plate. This led to early rehabilitation and speedy recovery with return to sporting activities by 12 months. PMID:20003496

Congenital Dislocation of the Hip

PubMed Central

Specht, Elmer E.

1976-01-01

Congenital dislocation or subluxation of the hip (congenital acetabular dysplasia) is a complete or partial displacement of the femoral head out of the acetabulum. The physical signs essential for diagnosis are age related. In newborns the tests for instability are the most sensitive. After the neonatal period, and until the age of walking, tightness of the adductor muscles is the most reliable sign. Early diagnosis is vital for successful treatment of this partially genetically determined condition. Various therapeutic measures, ranging from abduction splinting to open reduction and osteotomy, may be required. Following diagnosis in the first month of life, the average treatment time in one recent series was only 2.3 months from initiation of therapy to attainment of a normal hip. When the diagnosis was not made until 3 to 6 months of age, ten months of treatment was required to achieve the same outcome. When the diagnosis is not made, or the treatment is not begun until after the age of 6, a normal hip will probably not develop in any patient. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6.Figure 7.Figure 8.Figure 9. PMID:1251603

Acetabular cup position and risk of dislocation in primary total hip arthroplasty.

PubMed

Seagrave, Kurt G; Troelsen, Anders; Malchau, Henrik; Husted, Henrik; Gromov, Kirill

2017-02-01

Background and purpose - Hip dislocation is one of the most common complications following total hip arthroplasty (THA). Several factors that affect dislocation have been identified, including acetabular cup positioning. Optimal values for cup inclination and anteversion are debatable. We performed a systematic review to describe the different methods for measuring cup placement, target zones for cup positioning, and the association between cup positioning and dislocation following primary THA. Methods - A systematic search of literature in the PubMed database was performed (January and February 2016) to identify articles that compared acetabular cup positioning and the risk of dislocation. Surgical approach and methods for measurement of cup angles were also considered. Results - 28 articles were determined to be relevant to our research question. Some articles demonstrated that cup positioning influenced postoperative dislocation whereas others did not. The majority of articles could not identify a statistically significant difference between dislocating and non-dislocating THA with regard to mean angles of cup anteversion and inclination. Most of the articles that assessed cup placement within the Lewinnek safe zone did not show a statistically significant reduction in dislocation rate. Alternative target ranges have been proposed by several authors. Interpretation - The Lewinnek safe zone could not be justified. It is difficult to draw broad conclusions regarding a definitive target zone for cup positioning in THA, due to variability between studies and the likely multifactorial nature of THA dislocation. Future studies comparing cup positioning and dislocation rate should investigate surgical approach separately. Standardized tools for measurement of cup positioning should be implemented to allow comparison between studies.

Repeated posterior dislocation of total hip arthroplasty after spinal corrective long fusion with pelvic fixation.

PubMed

Furuhashi, Hiroki; Togawa, Daisuke; Koyama, Hiroshi; Hoshino, Hironobu; Yasuda, Tatsuya; Matsuyama, Yukihiro

2017-05-01

Several reports have indicated that anterior dislocation of total hip arthroplasty (THA) can be caused by spinal degenerative changes with excessive pelvic retroversion. However, no reports have indicated that posterior dislocation can be caused by fixed pelvic anteversion after corrective spine surgery. We describe a rare case experiencing repeated posterior THA dislocation that occurred at 5 months after corrective spinal long fusion with pelvic fixation. A 64-year-old woman had undergone bilateral THA at 13 years before presenting to our institution. She had been diagnosed with kyphoscoliosis and underwent three subsequent spinal surgeries after the THA. We finally performed spinal corrective long fusion from T5 to ilium with pelvic fixation (with iliac screws). Five months later, she experienced severe hip pain when she tried to stand up from the toilet, and was unable to move, due to posterior THA dislocation. Therefore, we performed closed reduction under sedation, and her left hip was easily reduced. After the reduction, she started to walk with a hip abduction brace. However, she had experienced 5 subsequent dislocations. Based on our findings and previous reports, we have hypothesized that posterior dislocation could be occurred after spinal corrective long fusion with pelvic fixation due to three mechanisms: (1) a change in the THA cup alignment before and after spinal corrective long fusion surgery, (2) decreased and fixed pelvic posterior tilt in the sitting position, or (3) the trunk's forward tilting during standing-up motion after spinopelvic fixation. Spinal long fusion with pelvic fixation could be a risk factor for posterior THA dislocation.

Acetabular cup position and risk of dislocation in primary total hip arthroplasty

PubMed Central

Seagrave, Kurt G; Troelsen, Anders; Malchau, Henrik; Husted, Henrik; Gromov, Kirill

2017-01-01

Background and purpose — Hip dislocation is one of the most common complications following total hip arthroplasty (THA). Several factors that affect dislocation have been identified, including acetabular cup positioning. Optimal values for cup inclination and anteversion are debatable. We performed a systematic review to describe the different methods for measuring cup placement, target zones for cup positioning, and the association between cup positioning and dislocation following primary THA. Methods — A systematic search of literature in the PubMed database was performed (January and February 2016) to identify articles that compared acetabular cup positioning and the risk of dislocation. Surgical approach and methods for measurement of cup angles were also considered. Results— 28 articles were determined to be relevant to our research question. Some articles demonstrated that cup positioning influenced postoperative dislocation whereas others did not. The majority of articles could not identify a statistically significant difference between dislocating and non-dislocating THA with regard to mean angles of cup anteversion and inclination. Most of the articles that assessed cup placement within the Lewinnek safe zone did not show a statistically significant reduction in dislocation rate. Alternative target ranges have been proposed by several authors. Interpretation— The Lewinnek safe zone could not be justified. It is difficult to draw broad conclusions regarding a definitive target zone for cup positioning in THA, due to variability between studies and the likely multifactorial nature of THA dislocation. Future studies comparing cup positioning and dislocation rate should investigate surgical approach separately. Standardized tools for measurement of cup positioning should be implemented to allow comparison between studies. PMID:27879150

21 CFR 890.3665 - Congenital hip dislocation abduction splint.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Congenital hip dislocation abduction splint. 890.3665 Section 890.3665 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890...

21 CFR 890.3665 - Congenital hip dislocation abduction splint.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Congenital hip dislocation abduction splint. 890.3665 Section 890.3665 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890...

21 CFR 890.3665 - Congenital hip dislocation abduction splint.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Congenital hip dislocation abduction splint. 890.3665 Section 890.3665 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890...

21 CFR 890.3665 - Congenital hip dislocation abduction splint.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Congenital hip dislocation abduction splint. 890.3665 Section 890.3665 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890...

Ipsilateral obturator type of hip dislocation with fracture shaft femur in a child: a case report and literature review.

PubMed

Arjun, R H H; Kumar, Vishal; Saibaba, Balaji; John, Rakesh; Guled, Uday; Aggarwal, Sameer

2016-09-01

The incidence of traumatic hip dislocations in children is rising in this fast developing world along with increasing numbers of high-velocity road traffic accidents. Anterior dislocation of the hip has a lower incidence compared with posterior dislocation of the hip. We encountered a rare case of the obturator type of anteriorly dislocated hip associated with ipsilateral fracture of the shaft femur in an 11-year-old child. This is a highly unusual injury combination and the mechanism of injury is obscure. Only two similar cases have been reported in the English literature to date. Closed reduction of the hip using a hitherto undescribed technique and an intramedullary interlocking nail was performed in this case. At 6 months of follow-up, the fracture shaft femur has united and the child is bearing full weight on the limb.

Can we prevent hip dislocation in children with cerebral palsy? Effects of postural management.

PubMed

Picciolini, Odoardo; LE Métayer, Michel; Consonni, Dario; Cozzaglio, Massimo; Porro, Matteo; Gasparroni, Verusca; Panou, Artemisia; Mosca, Fabio; Portinaro, Nicola M

2016-10-01

Hip dislocation is common in children with cerebral palsy (CP). At birth they do not have musculoskeletal deformities but they develop over time due to the combined effects of the movement disorder and impaired gross motor function. Early detection and treatment of a hip at risk is needed to modify the natural of hip development in CP. The aim of this study was to determine the effect of postural management treatment on hip displacement's progression in children CP. Prospective comparative non-randomized study. Rehabilitative outpatient unit. Fifty-one children with CP were studied; the treated group (N.=30) was compared to a control group (N.=21). The treated group followed a two year's long combined treatment program consisting a neurodevelopment treatment (NDT) two times a week and a 5 hours daily siège moulé postural program. The control group underwent only NDT twice a week for two years. Hip radiographs were measured with the migration percentage (MP) method at baseline, at 1 and 2 years of follow-up. A significant difference has been observed in the MP (%) trend (P<0.001) between treatment and control groups. At 2 years, there was a marked worsening (MP from 23.0 to 37.7) in the control group, compared to the stability (from 28.8 to 26.8) in the treatment group. This study supports the evidence that conservative postural management of hip deformity is useful to prevent the natural progression of hip dislocation. Hip radiographic follow up program together with NDT and postural management program is useful to modify the natural progression of hip dislocation in children with CP.

Intraoperative dislocation of the trial bipolar cup into the pelvis during bipolar hip arthroplasty - A case report.

PubMed

Miyake, Takahito; Kanda, Akio; Morohashi, Itaru; Obayashi, Osamu; Mogami, Atsuhiko; Kaneko, Kazuo

2017-06-01

Bipolar hip arthroplasty is a good option for treating femoral neck fractures, although some contraindications have been indicated. We report a case of intraoperative dislocation of the trial bipolar cup into the pelvis during bipolar hip arthroplasty. A 74-year-old woman underwent bipolar hip arthroplasty for a femoral neck fracture (AO31-B2). She was placed in a lateral decubitus position, and a direct lateral approach was used. During intraoperative trial reduction, the trial bipolar cup became disengaged and dislocated into the anterior space of hip joint. Several attempts to retrieve it failed. The permanent femoral component was inserted, and the wound was closed. The patient was repositioned supine to allow an ilioinguinal approach, and the component was easily removed. She had an uneventful, good recovery. Several cases of intraoperative dislocation of the femoral trial head during total hip arthroplasty have been reported, this is the first report of dislocation of a bipolar trial cup. A previous report described difficulty retrieving a trial cup. We easily removed our trial cup using another approach. It is vital to plan systematically for this frustrating complication.

Outcomes after salvage procedures for the painful dislocated hip in cerebral palsy.

PubMed

Wright, Patrick B; Ruder, John; Birnbaum, Mark A; Phillips, Jonathan H; Herrera-Soto, Jose A; Knapp, Dennis R

2013-01-01

The painful dislocated hip in the setting of cerebral palsy is a challenging problem. Many surgical procedures have been reported to treat this condition with varying success rates. The purpose of this study is to retrospectively evaluate and compare the outcomes of 3 different surgical procedures performed at our institution for pain relief in patients with spastic quadriplegic cerebral palsy and painful dislocated hips. A retrospective chart review of the surgical procedures performed by 5 surgeons for spastic, painful dislocated hips from 1997 to 2010 was performed. The procedures identified were (1) proximal femoral resection arthroplasty (PFRA); (2) subtrochanteric valgus osteotomy (SVO) with femoral head resection; and (3) proximal femur prosthetic interposition arthroplasty (PFIA) using a humeral prosthesis. Outcomes based on pain and range of motion were determined to be excellent, good, fair, or poor by predetermined criteria. Forty-four index surgeries and 14 revision surgeries in 33 patients with an average follow-up of 49 months met the inclusion criteria. Of the index surgeries, 12 hips were treated with a PFRA, 21 with a SVO, and 11 with a PFIA. An excellent or good result was noted in 67% of PFRAs, 67% of SVOs, and 73% of PFIAs. No statistical significance between these procedures was achieved. The 14 revisions were performed because of a poor result from previous surgery, demonstrating a 24% reoperation rate overall. No patients classified as having a fair result underwent revision surgery. All patients receiving revision surgery were eventually classified as having an excellent or good result. Surgical treatment for the painful, dislocated hip in the setting of spastic quadriplegic cerebral palsy remains unsettled. There continue to be a large percentage of failures despite the variety of surgical techniques designed to treat this problem. These failures can be managed, however, and eventually resulted in a good outcome. We demonstrated a trend

Congential dislocation of the hip and adult low back pain: a report of three cases

PubMed Central

Kitchen, Robert G; Mierau, Dale; Cassidy, David; Dupuis, Pierre

1988-01-01

Congenital dislocation of the hip (CDH) in an adult can accompany or cause mechanical low-back pain. This in turn, can create confusion in making the proper diagnosis. The mechanical alterations caused by CDH create an added strain to the lumbosacral spine. Manipulative treatment for back pain in these patients must not subject the dislocated hips to undue torque. ImagesFigure 1Figure 2Figure 3Figure 4aFigure 4b

[Relevance of MRI After Closed Reduction of Traumatic Hip Dislocation in Children].

PubMed

Strüwind, Christoph Mauritz; von Rüden, Christian; Thannheimer, Andreas; Bühren, Volker; Schneidmueller, Dorien

2018-05-14

Traumatic hip dislocation in children and adolescents is a rare entity that typically results from high-energy trauma. After closed joint reduction, further treatment depends on the specific pattern of the lesion as identified using cross sectional imaging. The aim of this retrospective analysis was to evaluate relevant side effects after traumatic hip dislocation in children and adolescents in order to examine the need for focused diagnostics. This retrospective analysis covered 8 adolescents under 18 years suffering isolated traumatic hip joint dislocation between 2001 and 2017. In all patients, closed joint reduction was performed immediately after admission to the emergency room. In order to evaluate the complete extent of the injury, 5 patients received an MRI and 3 patients a CT scan following closed joint reduction. Two female and 6 male patients with a median age of 11 (range 5 - 16) years were included. In 2 cases, a free joint body was detected in the posterior joint gap in the posttraumatic CT scan after closed joint reduction. Interposition of the labrum into the joint gap was detected intraoperatively in both cases. In one patient who received posttraumatic MRI, labral interposition into the joint gap was observed after closed reduction. These findings were confirmed intraoperatively. In 4 other patients, no posttraumatic labral lesion was detected in the MRI after closed reduction. The reported side effects included ruptured anterior inferior iliac spine and ruptured femoral head ligament. MRI is gaining increasing importance following traumatic hip dislocation in children and adolescents. A missing chondral or osteochondral fragment in the CT scan does not exclude a labral lesion or interposition. Therefore, MRI following closed reduction is mandatory in any case. Georg Thieme Verlag KG Stuttgart · New York.

Surgical dislocation of the hip and the management of femoroacetabular impingement: results of the Christchurch experience.

PubMed

Kempthorne, Joshua T; Armour, Paul C; Rietveld, John A; Hooper, Gary J

2011-06-01

Surgical dislocation of the hip has been developed to deal with the problems causing femoroacetabular impingement (FAI). This is a relatively recent procedure that was historically reserved for larger areas specializing in hip surgery. We hypothesized that surgical dislocation can be used for symptomatic FAI in a typical Australasian tertiary orthopaedic centre with acceptable results. This prospective study reviews the results of 53 surgical dislocations in this setting, looking particularly at functional outcomes and early complications. There were significant improvements in the Western Ontario and McMaster University Osteoarthritis Index score at 1, 2, 3 and 4 years post-operatively. Western Ontario and McMaster University Osteoarthritis Index scores increased by 23, 28, 34 and 35 points, respectively (P 0.0039). There was no significant improvement in hip range of motion. There were two (4%) early failures with conversion to total hip arthroplasty, and no cases of post-operative avascular necrosis of the femoral head. We believe that as the diagnosis of FAI and conservative nonarthroplasty surgery of the hip gains wider acceptance, it will become a procedure that should be offered to all appropriate patients in an attempt to delay or limit total hip arthroplasty in this young age group.

A syndrome of dislocated hips and radial heads, carpal coalition, and short stature in Puerto Rican children.

PubMed

Steel, H H; Piston, R W; Clancy, M; Betz, R R

1993-02-01

An orthopaedic syndrome that apparently had not been reported previously was identified in twenty-three children. Characteristics shared by all twenty-three children included Hispanic descent, residence in Puerto Rico, bilateral dislocation of the hip, dislocated radial heads, short stature, and other osseous anomalies. Twelve dislocated hips in six patients were not treated. All of these hips were functioning satisfactorily at the time of the review, but only four of the children had reached skeletal maturity. Sixteen hips in eight patients remained reduced after closed reduction. Of these eight patients, the four who were skeletally immature at the time of the review had a satisfactory result, and the four who were skeletally mature had an unsatisfactory result because of discomfort or fibrous ankylosis. Eighteen hips in nine patients were treated with a reduction augmented by some form of operation. All of these hips redislocated. Of the forty-six elbows in the twenty-three children, thirty-three were dislocated, as seen clinically and radiographically; eight were normal, both clinically and radiographically; and there was dysplasia at the radiocapitellar articulation of the remaining five. Twenty of the twenty-three children were found to have carpal coalitions. Fourteen children had scoliosis, and five of them were managed with spinal arthrodesis and correction. Three patients had an anomaly of the cervical spine, with one deformity causing symptoms and signs that were treated with decompression. Eight patients had talipes cavus bilaterally, which was not treated.

Rocket launcher: A novel reduction technique for posterior hip dislocations and review of current literature.

PubMed

Dan, Michael; Phillips, Alfred; Simonian, Marcus; Flannagan, Scott

2015-06-01

We provide a review of literature on reduction techniques for posterior hip dislocations and present our experience with a novel technique for the reduction of acute posterior hip dislocations in the ED, 'the rocket launcher' technique. We present our results with six patients with prosthetic posterior hip dislocation treated in our rural ED. We recorded patient demographics. The technique involves placing the patient's knee over the shoulder, and holding the lower leg like a 'Rocket Launcher' allow the physician's shoulder to work as a fulcrum, in an ergonomically friendly manner for the reducer. We used Fisher's t-test for cohort analysis between reduction techniques. Of our patients, the mean age was 74 years (range 66 to 85 years). We had a 83% success rate. The one patient who the 'rocket launcher' failed in, was a hemi-arthroplasty patient who also failed all other closed techniques and needed open reduction. When compared with Allis (62% success rate), Whistler (60% success rate) and Captain Morgan (92% success rate) techniques, there was no statistically significant difference in the successfulness of the reduction techniques. There were no neurovascular or periprosthetic complications. We have described a reduction technique for posterior hip dislocations. Placing the patient's knee over the shoulder, and holding the lower leg like a 'Rocket Launcher' allow the physician's shoulder to work as a fulcrum, thus mechanically and ergonomically superior to standard techniques. © 2015 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

Arthroscopic Anterior and Posterior Labral Repair After Traumatic Hip Dislocation: Case Report and Review of the Literature

PubMed Central

Shindle, Michael K.; Kelly, Bryan T.

2010-01-01

With the improvements in flexible instrumentation, hip arthroscopy is being increasingly used to treat a variety of hip pathology, including labral tears. However, up to this point, there has not been a case report of an anterior and a posterior labral tear successfully repaired arthroscopically. We present a case report of a 27-year-old male firefighter who presented to our institution with an anterior and posterior labral tear, as well as a cam lesion and loose body, following a traumatic hip dislocation. The purpose of this case report is to illustrate that both anterior and posterior labral tears can be repaired using hip arthroscopy. Anterior and posterior labral tears can be caused by a traumatic hip dislocation, and both can be successfully repaired using arthroscopic techniques. PMID:21886540

Late septic hip dislocation with multifocal osteomyelitis and malaria: a case report.

PubMed

Sreenivas, T; Menon, Jagdish; Nataraj, A R

2012-12-01

A 9-year-old boy presented with high-grade fever associated with pain and swelling in right hip and left leg of 1-week duration. Pus was found on diagnostic aspiration of the right hip joint. Emergency arthrotomy was performed through anterior approach with drill holes in proximal femur and culture showed MRSA. Intravenous antibiotics were given for 4 weeks. Patient symptomatically improved in immediate postoperative period and in bed hip mobilization was started. On eighth postoperative day, child developed high-grade intermittent fever with chills and rigors and diagnosed as plasmodium falciparum malaria. Fever subsided with antimalarial treatment. On twenty-first day, patient complained pain in right hip and X-ray showed posterior hip dislocation with osteomyelitis of proximal femur. Closed reduction and hip spica application was done under general anesthesia. At follow-up, the clinical result was fair with resolution of infection and stiff hip.

Ligamentum teres tenodesis in medial approach open reduction for developmental dislocation of the hip.

PubMed

Bache, Christopher Edward; Graham, H Kerr; Dickens, D Robert V; Donnan, Leo; Johnson, Michael B; Nattrass, Gary; O'Sullivan, Mark; Torode, Ian P

2008-09-01

When closed reduction of a developmental dislocation of the hip fails, some form of open reduction is required. In recent years, the many advantages of the medial approach open reduction have been emphasized. However, there have been suggestions that the rate of growth disturbance in the proximal femur and the requirement for secondary surgical procedures may be higher with this route than with others. The purpose of this study was to investigate the efficacy and safety of a modified medial approach open reduction, in which the stability of the reduction is enhanced by resection of the redundant ligamentum teres and suturing of the stump of the tendon to the anteromedial capsule. The hospital records and radiographs of 92 infants and children with 109 dislocated hips were reviewed retrospectively. Key demographic and pretreatment data were collected by the first author and compared with the outcome at the most recent follow-up. In addition, 69 children returned for a clinical evaluation by the first author. The outcome at the most recent follow-up was graded according to Severin, and associations were sought between pretreatment grade of dislocation according to Tonnis, the presence of ossific nucleus, changes in the acetabular index, the requirements for secondary surgery, associations with previous treatment, and the position of abduction in the postoperative cast. At a mean follow-up of 9 years, 89% of hips were classified as Severin grade 1 or 2. Avascular necrosis (AVN) was classified according to the system of Kalamchi and MacEwen. The incidence of AVN was 41%, but two thirds of these were grade 1 (temporary irregular ossification), and the Severin grading in these hips was not compromised. The presence of ossification in the capital epiphysis and a range of abduction of less than 60 degrees in the hip spica were noted to be protective against the development of AVN. Three hips redislocated and required additional treatment. Thirty-eight hips required a total

Dislocations

MedlinePlus

... or a blow, sometimes from playing a contact sport. You can dislocate your ankles, knees, shoulders, hips, ... to dislocate it again. Wearing protective gear during sports may help prevent dislocations.

Position of the prosthesis and the incidence of dislocation following total hip replacement.

PubMed

He, Rong-xin; Yan, Shi-gui; Wu, Li-dong; Wang, Xiang-hua; Dai, Xue-song

2007-07-05

Dislocation is the second most common complication of hip replacement surgery, and impact of the prosthesis is believed to be the fundamental reason. The present study employed Solidworks 2003 and MSC-Nastran software to analyze the three dimensional variables in order to investigate how to prevent dislocation following hip replacement surgery. Computed tomography (CT) imaging was used to collect femoral outline data and Solidworks 2003 software was used to construct the cup model with variabilities. Nastran software was used to evaluate dislocation at different prosthesis positions and different geometrical shapes. Three dimensional movement and results from finite element method were analyzed and the values of dislocation resistance index (DRI), range of motion to impingement (ROM-I), range of motion to dislocation (ROM-D) and peak resisting moment (PRM) were determined. Computer simulation was used to evaluate the range of motion of the hip joint at different prosthesis positions. Finite element analysis showed: (1) Increasing the ratio of head/neck increased the ROM-I values and moderately increased ROM-D and PRM values. Increasing the head size significantly increased PRM and to some extent ROM-I and ROM-D values, which suggested that there would be a greater likelihood of dislocation. (2) Increasing the anteversion angle increased the ROM-I, ROM-D, PRM, energy required for dislocation (ENERGY-D) and DRI values, which would increase the stability of the joint. (3) As the chamber angle was increased, ROM-I, ROM-D, PRM, Energy-D and DRI values were increased, resulting in improved joint stability. Chamber angles exceeding 55 degrees resulted in increases in ROM-I and ROM-D values, but decreases in PRM, Energy-D, and DRI values, which, in turn, increased the likelihood of dislocation. (4) The cup, which was reduced posteriorly, reduced ROM-I values (2.1 -- 5.3 degrees ) and increased the DRI value (0.073). This suggested that the posterior high side had the

Undisplaced Intraoperative Fracture Presenting as Early Dislocation with Tapered Wedge Stems in Total Hip Arthroplasty - Case Series and Review of Literature

PubMed Central

Reddy, A V Gurava; Eachempati, Krishna Kiran; Mugalur, Aakash; Suchinder, A; Rao, V B N Prasad; Kamurukuru, Nalanda

2017-01-01

Introduction: Periprosthetic fractures and dislocation in the early post-operative period can be disastrous both for the surgeon and the patient. However, undisplaced periprosthetic fractures presenting with dislocation is uncommon. We describe successful management of two cases (one bilateral dislocation and one unilateral dislocation) of undisplaced iatrogenic fractures in total hip arthroplasty (THA) presenting as early dislocation. Case Report: Case 1 was a 45-year-old female with osteoarthritis of hip secondary to developmental dysplasia of the hip with bilateral early nontraumatic dislocation with bilateral identical periprosthetic fracture. It was managed by revision to long stem and encirclage wiring. Case 2 presented with early dislocation in the 2nd week post THA. We found an intertrochanteric fracture intra-operatively with unstable implant. Acetabular component and femoral component revision were done with reconstruction of the greater trochanter. Discussion: These fractures could be occult iatrogenic fractures characteristic of taper wedge stems which presented as early nontraumatic dislocation in the post-operative period. The prosthesis subsidence, loss of muscle tension and change of version might be the factors leading to dislocation. Conclusion: Unrecognized incomplete intraoperative fracture can occur with tapered wedge uncemented stems which can present as a dislocation in the immediate post-operative period. This will require early revision of the femoral component. PMID:29051875

Cementless total hip arthroplasty for severely dislocated hips previously treated with Schanz osteotomy of the proximal femur.

PubMed

Akman, Yunus Emre; Yavuz, Umut; Çetinkaya, Engin; Gür, Volkan; Gül, Murat; Demir, Bilal

2018-03-01

We report the short-term outcomes of total hip arthroplasty(THA) in patients previously treated with Schanz osteotomy (SO). Eighteen patients [2 male, 16 female; mean age, 55.4 (range, 50-66) years] who had undergone THA after SO were retrospectively evaluated. Clinical evaluation was performed based on the Harris hip score. Radiological evaluation was performed using full-length radiographs of the lower extremities, pelvis, and hip. The mean follow-up period was 30.8 (range, 18-56) months. Mean femoral shortening was 3.7 (range, 2-5) cm. Perioperative complications occurred in 4 (22.2%) patients. Nonunion was not found at the osteotomy sites. No dislocation was observed. The Trendelenburg sign was positive for five (27.7%) patients, postoperatively. The mean Harris hip score improved from 42.7 to 78.7 (p < 0.05). THA for hips previously treated with SO is technically demanding. If careful preoperative planning is performed, successful treatment can be achieved.

What Are the Risk Factors for Dislocation of Hip Bipolar Hemiarthroplasty Through the Anterolateral Approach? A Nested Case-control Study.

PubMed

Li, Lianhua; Ren, Jixin; Liu, Jia; Wang, Hao; Sang, Qinghua; Liu, Zhi; Sun, Tiansheng

2016-12-01

Hip dislocation after treatment of a femoral neck fracture with a hemiarthroplasty remains an important problem in the treatment of hip fractures, but the associations between patient factors and surgical factors, and how these factors contribute to dislocation in patients who have undergone bipolar hemiarthroplasty through an anterolateral approach for femoral neck fracture currently are only poorly characterized. We evaluated patients with bipolar hemiarthroplasty dislocation after surgery for femoral neck fracture treated through an anterolateral approach and asked: (1) What are the frequency, characteristics, and risk factors of bipolar hemiarthroplasty dislocations? (2) What are the frequency, characteristics, and risk factors of bipolar hemiarthroplasty dissociations? A review of hospital records for patients who underwent bipolar hip hemiarthroplasty for femoral neck fracture at one hospital between July 2004 and August 2014 was conducted. During that time, 1428 patients were admitted with a diagnosis of femoral neck fracture; 508 of these patients underwent bipolar hip hemiarthroplasty, of whom 61 died and 23 were lost to followup during the first year, leaving 424 (83%) available for analysis. The remainder of the patients during that time were treated with internal fixation (512), unipoloar hip arthroplasty (17), or THA (391). For each patient with dislocation, we selected five control patients from the cohort according to sex, age (± 3 years), and year of entry in the study to eliminate some confounding factors. We recorded patient characteristics regarding demographics, medical comorbidities, Katz score, American Society of Anesthesiologists score, Mini-Mental State Examination (MMSE) score, and anesthesia type. Medical comorbidities included diabetes, chronic pulmonary disease, heart disease, neuromuscular diseases, and dementia. Univariate analyses were used to search for possible risk factors. Conditional logistic regression analyses on dislocation

Utilization of the Safe Surgical Dislocation Approach of the Hip to Retrieve a Bullet from the Femoral Head

PubMed Central

Delaney, Ruth; Albright, Maurice; Rebello, Gleeson

2011-01-01

Retained intra-articular missiles from low-velocity handguns can lead to mechanical arthritis, synovitis, and lead toxicity. Various surgical approaches have been described to extract such foreign bodies from the hip joint. We present the case of a 17-year-old male in which the surgical dislocation approach was utilized to retrieve a bullet from the femoral head with a good short-term outcome. This case represents a rare application of the surgical hip dislocation approach for an unusual trauma. PMID:23198205

Prosthetic hip dislocations: is relocation in the emergency department by emergency medicine staff better?

PubMed

Lawrey, Emma; Jones, Peter; Mitchell, Robin

2012-04-01

Prosthetic hip dislocation is common. This study compares prosthetic hip relocations attempted within the ED by emergency doctors and those under orthopaedic care in the ED or operating theatre (OT). Retrospective cohort study of patients presenting to Auckland City Hospital Adult Emergency Department with prosthetic hip dislocations between 1 January 2003 and 14 April 2008. Primary outcomes were proportion of successful relocation attempts and length of hospital stay. Secondary outcomes were: time to relocation, complications, post-procedural advice, representation rate and long-term outcomes for first-time dislocations. There were 410 eligible presentations during the study period. Emergency medicine (EM) was successful in 254/323 attempts (79%, 95% confidence interval [CI] 74-83). Orthopaedics were successful in 25/35 reductions in the ED (71%, 95% CI 55-84) and 49/51 OT attempts (96%, 95% CI 86-100), P = 0.004 for location OT versus ED. Median times to discharge were 8.8 h for EM, 28.3 h for orthopaedics in the ED and 81 h for orthopaedics in the OT, P < 0.001 for EM versus orthopaedics. Mechanical complications of procedures and early redislocations were infrequent. Complication of sedation were more often seen in OT compared to ED (23/47 [49%, 95% CI 35-63]vs 37/318 [12%, 95% CI 9-16]). There was no difference between EM and orthopaedics in the proportion of hips successfully relocated or complications in the ED; however, EM patients were discharged much sooner, with important resource implications. Procedures carried out in the OT were more successful than in the ED but resulted in prolonged hospital stays and were associated with more complications. © 2012 The Authors. EMA © 2012 Australasian College for Emergency Medicine and Australasian Society for Emergency Medicine.

Radiographic comparison of surgical hip dislocation and hip arthroscopy for treatment of cam deformity in femoroacetabular impingement.

PubMed

Bedi, Asheesh; Zaltz, Ira; De La Torre, Katrina; Kelly, Bryan T

2011-07-01

Whether open or arthroscopic techniques are employed, the goal of femoroacetabular impingement (FAI) surgery is to achieve impingement-free range of motion. While arthroscopic approaches have improved and gained popularity, an objective evaluation of the surgical correction achieved with this approach compared with open surgery remains to be defined in the literature. This study was undertaken to compare the efficacy of arthroscopic osteoplasty and open surgical dislocation in treating FAI dysmorphology in a consecutive series of patients. Cohort study; Level of evidence, 3. Surgical treatment was performed in 60 male patients under 40 years of age for symptomatic FAI refractory to nonoperative management. Patients were matched (not randomized) to treatment groups: 30 patients (15 left and 15 right hips) underwent arthroscopic cam and/or rim osteoplasty with labral debridement and/or refixation by an arthroscopic surgeon; and 30 (14 left and 16 right hips) underwent open surgical dislocation, cam and/or rim osteoplasty, and labral debridement or refixation by a hip preservation surgeon. Anteroposterior (AP) pelvis and extended-neck (Dunn) lateral radiographs were obtained and the depth of resection and arc of resection were measured by assessment of anterior femoral head-neck offset, AP and lateral α angle, and β angle on preoperative and postoperative radiographs. In the arthroscopic group, the extended-neck lateral α angle was reduced by a mean of 17.2° (28.3%, P < .05), AP α angle was reduced by a mean of 12.6° (16.8%), anterior head-neck offset improved 5.0 mm (111%, P < .05), and β angle increased by a mean of 23.1°. In the open dislocation group, the extended-neck lateral α angle was reduced by a mean of 21.2° (30.7%, P < .05), AP α angle was reduced by a mean of 20.1° (25.7%), anterior head-neck offset improved 6.56 mm (108%, P < .05), and β angle increased by a mean of 18.35°. Arthroscopic osteoplasty can restore head-neck offset and achieve

Avascular necrosis as a complication of the treatment of dislocation of the hip in children with cerebral palsy.

PubMed

Koch, A; Jozwiak, M; Idzior, M; Molinska-Glura, M; Szulc, A

2015-02-01

We investigated the incidence and risk factors for the development of avascular necrosis (AVN) of the femoral head in the course of treatment of children with cerebral palsy (CP) and dislocation of the hip. All underwent open reduction, proximal femoral and Dega pelvic osteotomy. The inclusion criteria were: a predominantly spastic form of CP, dislocation of the hip (migration percentage, MP > 80%), Gross Motor Function Classification System, (GMFCS) grade IV to V, a primary surgical procedure and follow-up of > one year. There were 81 consecutive children (40 girls and 41 boys) in the study. Their mean age was nine years (3.5 to 13.8) and mean follow-up was 5.5 years (1.6 to 15.1). Radiological evaluation included measurement of the MP, the acetabular index (AI), the epiphyseal shaft angle (ESA) and the pelvic femoral angle (PFA). The presence and grade of AVN were assessed radiologically according to the Kruczynski classification. Signs of AVN (grades I to V) were seen in 79 hips (68.7%). A total of 23 hips (18%) were classified between grades III and V. Although open reduction of the hip combined with femoral and Dega osteotomy is an effective form of treatment for children with CP and dislocation of the hip, there were signs of avascular necrosis in about two-thirds of the children. There was a strong correlation between post-operative pain and the severity of the grade of AVN. ©2015 The British Editorial Society of Bone & Joint Surgery.

Reducing the rate of early primary hip dislocation by combining a change in surgical technique and an increase in femoral head diameter to 36 mm.

PubMed

Ho, Ki Wai Kevin; Whitwell, George S; Young, Steve K

2012-07-01

We report how changes to our total hip arthroplasty (THA) surgical practise lead to a decrease in early hip dislocation rates. Group B consisted of 421 consecutive primary THA operations performed via a posterior approach. The operative technique included a meticulous repair of the posterior capsule, alignment of the acetabular cup with the transverse acetabular ligament (TAL) and a 36-mm-diameter femoral head. We compared the dislocation rates and cost implications of this technique to a historical control Group A consisting of 389 patients. The control group had their THA performed with no repair of the capsule, no identification of the TAL and all received a 28-mm-diameter head. Our primary outcome is the rate of early hip dislocation and we hypothesised that we can reduce the rate of early hip dislocation with this new regime. In Group B there were no early dislocations (within 6 months) and two (0.5 %) dislocations within 18 months; minimum follow-up time was 18 months with a range of (18-96 months). This compared to a 1.8 % early dislocation rate and a 2.6 % rate at 18 months in Group A; minimum follow-up time was 60 months with a range of (60-112 months). These results were statistically significant (p = 0.006). We suggest that when primary hip arthroplasty is performed through a posterior approach, a low early dislocation rate can be achieved using the described methods.

Proximal femoral resection and articulated hip distraction with an external fixator for the treatment of painful spastic hip dislocations in pediatric patients with spastic quadriplegia.

PubMed

Lampropulos, Mario; Puigdevall, Miguel H; Zapozko, Daniel; Malvárez, Héctor R

2008-01-01

We describe the results obtained with an alternative method of treatment for spastic painful hip dislocations in nonambulatory patients, which consists of a proximal femoral resection with capsular interposition arthroplasty, and the addition of a hinged external fixator for postoperative articulated hip distraction to allow for an immediate upright position and the ability to sit in a wheelchair. We performed this technique in three patients (four hips) with a mean age at the time of surgery of 15 years. Postoperatively, clinical improvement was observed in all four hips, with respect to pain relief, sitting tolerance, perineal care and functional range of motion.

Use of a constrained tripolar acetabular liner to treat intraoperative instability and postoperative dislocation after total hip arthroplasty: a review of our experience.

PubMed

Callaghan, John J; O'Rourke, Michael R; Goetz, Devon D; Lewallen, David G; Johnston, Richard C; Capello, William N

2004-12-01

Constrained acetabular components have been used to treat certain cases of intraoperative instability and postoperative dislocation after total hip arthroplasty. We report our experience with a tripolar constrained component used in these situations since 1988. The outcomes of the cases where this component was used were analyzed for component failure, component loosening, and osteolysis. At average 10-year followup, for cases treated for intraoperative instability (2 cases) or postoperative dislocation (4 cases), the component failure rate was 6% (6 of 101 hips in 5 patients). For cases where the constrained liner was cemented into a fixed cementless acetabular shell, the failure rate was 7% (2 of 31 hips in 2 patients) at 3.9-year average followup. Use of a constrained liner was not associated with an increased osteolysis or aseptic loosening rate. This tripolar constrained acetabular liner provided total hip arthroplasty construct stability in most cases in which it was used for intraoperative instability or postoperative dislocation.

Experience of the posterior lip augmentation device in a regional hip arthroplasty unit as a treatment for recurrent dislocation.

PubMed

Hoggett, L; Cross, C; Helm, T

2017-12-01

Dislocation after total hip arthroplasty (THA) remains a significant complication of the procedure and is the third leading cause for revision THA. One technique for treatment of this complication is the use of the posterior lip augmentation device (PLAD). We describe our experience using the PLAD including complication rates. A retrospective review of 55 PLADs (54 patients) was carried out following identification from electronic theatre records. Basic patient demographics, operative records and radiographs were collected and reviewed and data was analysed using Microsoft Excel. Failure of the PLAD was defined as further operative intervention after PLAD insertion and included: dislocation, implant breakage, infection and revision of the THA for loosening of either component. 55 PLADs were implanted in 54 patients with an average age of 77 years. There was a significant preponderance of females and a variety of surgical approaches had been used for the original hip replacement, including trochanteric osteotomy, posterior and antero-lateral. 9 (16%) patients had recurrent dislocations,1 (2%) failed secondary to screw breakage, 3 (5%) had and infection requiring intervention and 2 (4%) underwent further revision for aseptic loosening of the femoral component. The overall failure rate was 25% with 14 patients requiring intervention post PLAD. Our results are inferior to other published results and indicate that the PLAD should be used with caution for recurrent dislocations of the Charnley hip replacement.

Implementing Capsule Representation in a Total Hip Dislocation Finite Element Model

PubMed Central

Stewart, Kristofer J; Pedersen, Douglas R; Callaghan, John J; Brown, Thomas D

2004-01-01

Previously validated hardware-only finite element models of THA dislocation have clarified how various component design and surgical placement variables contribute to resisting the propensity for implant dislocation. This body of work has now been enhanced with the incorporation of experimentally based capsule representation, and with anatomic bone structures. The current form of this finite element model provides for large deformation multi-body contact (including capsule wrap-around on bone and/or implant), large displacement interfacial sliding, and large deformation (hyperelastic) capsule representation. In addition, the modular nature of this model now allows for rapid incorporation of current or future total hip implant designs, accepts complex multi-axial physiologic motion inputs, and outputs case-specific component/bone/soft-tissue impingement events. This soft-tissue-augmented finite element model is being used to investigate the performance of various implant designs for a range of clinically-representative soft tissue integrities and surgical techniques. Preliminary results show that capsule enhancement makes a substantial difference in stability, compared to an otherwise identical hardware-only model. This model is intended to help put implant design and surgical technique decisions on a firmer scientific basis, in terms of reducing the likelihood of dislocation. PMID:15296198

Concomitant Posterior Hip Dislocation, Ipsilateral Intertrochanteric- and Proximal Tibial- Fractures with Popliteal Artery Injury: A Challenging Trauma Mélange.

PubMed

Chotai, Pranit N; Ebraheim, Nabil A; Hart, Ryan; Wassef, Andrew

2015-11-05

Constellation of ipsilateral posterior hip dislocation, intertrochanteric- and proximal tibial fracture with popliteal artery injury is rare. Management of this presentation is challenging. A motor vehicle accident victim presented with these injuries, but without any initial signs of vascular compromise. Popliteal artery injury was diagnosed intra-operatively and repaired. This was followed by external fixation of tibial fracture, open reduction of dislocated hip and internal fixation of intertrochanteric fracture. Patient regained bilateral complete weight bearing and returned to pre-accident activity level. Apt surgical management including early repair of vascular injury in such a trauma mélange allows for a positive postoperative outcome.

Effect of femoral head size and surgical approach on risk of revision for dislocation after total hip arthroplasty

PubMed Central

Zijlstra, Wierd P; De Hartog, Bas; Van Steenbergen, Liza N; Scheurs, B Willem; Nelissen, Rob G H H

2017-01-01

Background and purpose Recurrent dislocation is the commonest cause of early revision of a total hip arthropasty (THA). We examined the effect of femoral head size and surgical approach on revision rate for dislocation, and for other reasons, after total hip arthroplasty (THA). Patients and methods We analyzed data on 166,231 primary THAs and 3,754 subsequent revision THAs performed between 2007 and 2015, registered in the Dutch Arthroplasty Register (LROI). Revision rate for dislocation, and for all other causes, were calculated by competing-risk analysis at 6-year follow-up. Multivariable Cox proportional hazard regression ratios (HRs) were used for comparisons. Results Posterolateral approach was associated with higher dislocation revision risk (HR =1) than straight lateral, anterolateral, and anterior approaches (HR =0.5–0.6). However, the risk of revision for all other reasons (especially stem loosening) was higher with anterior and anterolateral approaches (HR =1.2) and lowest with posterolateral approach (HR =1). For all approaches, 32-mm heads reduced the risk of revision for dislocation compared to 22- to 28-mm heads (HR =1 and 1.6, respectively), while the risk of revision for other causes remained unchanged. 36-mm heads increasingly reduced the risk of revision for dislocation but only with the posterolateral approach (HR =0.6), while the risk of revision for other reasons was unchanged. With the anterior approach, 36-mm heads increased the risk of revision for other reasons (HR =1.5). Interpretation Compared to the posterolateral approach, direct anterior and anterolateral approaches reduce the risk of revision for dislocation, but at the cost of more stem revisions and other revisions. For all approaches, there is benefit in using 32-mm heads instead of 22- to 28-mm heads. For the posterolateral approach, 36-mm heads can safely further reduce the risk of revision for dislocation. PMID:28440704

What are the risk factors for dislocation in primary total hip arthroplasty? A multicenter case-control study of 128 unstable and 438 stable hips.

PubMed

Fessy, M H; Putman, S; Viste, A; Isida, R; Ramdane, N; Ferreira, A; Leglise, A; Rubens-Duval, B; Bonin, N; Bonnomet, F; Combes, A; Boisgard, S; Mainard, D; Leclercq, S; Migaud, H

2017-09-01

Dislocation after total hip arthroplasty (THA) is a leading reason for surgical revision. The risk factors for dislocation are controversial, particularly those related to the patient and to the surgical procedure itself. The differences in opinion on the impact of these factors stem from the fact they are often evaluated using retrospective studies or in limited patient populations. This led us to carry out a prospective case-control study on a large population to determine: 1) the risk factors for dislocation after THA, 2) the features of these dislocations, and 3) the contribution of patient-related factors and surgery-related factors. Risk factors for dislocation related to the patient and procedure can be identified using a large case-control study. A multicenter, prospective case-control study was performed between January 1 and December 31, 2013. Four patients with stable THAs were matched to each patient with a dislocated THA. This led to 566 primary THA cases being included: 128 unstable, 438 stable. The primary matching factors were sex, age, initial diagnosis, surgical approach, implantation date and type of implants (bearing size, standard or dual-mobility cup). The patients with unstable THAs were 67±12 [37-73]years old on average; there were 61 women (48%) and 67 men (52%). Hip osteoarthritis (OA) was the main reason for the THA procedure in 71% (91/128) of the unstable group. The dislocation was posterior in 84 cases and anterior in 44 cases. The dislocation occurred within 3 months of the primary surgery in 48 cases (38%), 3 to 12 months after in 23 cases (18%), 1 to 5years after in 20 cases (16%), 5 to 10years after in 17 cases (13%) and more than 10years later in 20 cases. The dislocation recurred within 6 months of the initial dislocation in 23 of the 128 cases (18%). The risk factors for instability were a high ASA score with an odds ratio (OR) of 1.93 (95% CI: 1.4-2.6), neurological disability (cognitive, motor or psychiatric disorders) with

Influence of age on the outcome of single stage reconstructive surgery for congenital dislocation of the hip joint.

PubMed

Bhatti, Anisuddin; Jamali, A R; Mehboob, Ghulam

2009-01-01

This study was conducted to assess the effect of age on the ultimate outcome measures following single stage surgical procedure of soft tissue release, relocation, capsulorrhaphy, femoral shortening with varus/derotation osteotomy and pelvic osteotomy. A case series. The study with two groups of pretest-posttest design was conducted at Department of Orthopaedic Surgery, Jinnah Postgraduate Medical Centre (JPMC), Karachi, from 1993 to January 2008. Patients included were having neglected, congenital dislocation of the hip joint, aged over 3 years. Patients with failed previous surgery, paralytic, teratological, traumatic or septic dislocations and patients with less than 5 years follow-up were excluded from the study. The patients were divided into two groups, 3-7 years (37 hip joints) and over 7 years (13 hip joints). The single stage surgical procedure of open relocation, femoral shortening/derotation/ varus osteotomy and pelvic osteotomy was the dependent variable; whereas, the final clinico-radiological results based upon Tonnis grading, Severin's clinical/radiological grading, Klisic's overall rating and acetabular index were the independent variables of the study. Pre- and postoperative data was assessed for overall improvement and the difference in outcome measures between the two age groups. Significant overall improvement on all parameters was achieved after surgery. When results were compared between two age groups, there was no significant difference in the final outcome as per Tonnis grading and Severin's clinical typing as modified by Gibson (97.3% versus 84.4% normal hip joints or Tonnis grade 1 and 78.37% versus 53.85% Severin's type 1) but the results based upon Severin's radiological grading (62.16% versus 15.38%) and Klisic's overall rating (62.16% versus 15.38%) were significantly better in 3-7 years as compared to those over 7 years. There was no significant difference between the two age groups when compared for improvement in acetabular index

Large-diameter metal-on-metal total hip arthroplasty: dislocation infrequent but survivorship poor.

PubMed

Lombardi, Adolph V; Berend, Keith R; Morris, Michael J; Adams, Joanne B; Sneller, Michael A

2015-02-01

Use of large-diameter metal-on-metal (MoM) articulations in THA increased, at least in part, because of the possibility of achieving improved joint stability and excellent wear characteristics in vitro. However, there have been subsequent concerning reports with adverse reactions to metal debris (ARMD), pseudotumors, and systemic complications related to metal ions. The purpose of this study was to determine at a minimum of 2 years' followup (1) the proportion of patients who experienced a dislocation; (2) the short-term survivorship obtained with these implants; (3) the causes of failure and the proportion of patients who developed ARMD; and (4) whether there were any identifiable risk factors for revision. We reviewed the results of 1235 patients who underwent 1440 large-diameter MoM primary THAs at our institution using two acetabular devices from a single manufacturer with minimum 2-year followup. Large-diameter MoM devices were used in 48% (1695 of 3567) of primary THAs during the study period. We generally used these implants in younger, more active, higher-demand patients, in patients considered at higher risk of instability, and in patients with adequate bone stock to achieve stable fixation without use of screws. Clinical records and radiographs were reviewed to determine the incidence and etiology of revision. Patients whose hips were revised were compared with those not revised to identify risk factors; Kaplan-Meier survivorship analysis was performed as was multivariate analysis to account for potential confounding variables when evaluating risk factors. Minimum followup was 2 years (average, 7 years; range, 2-12 years); complete followup was available in 85% of hips (1440 of 1695). Dislocation occurred in one hip overall (<1%; one of 1440). Kaplan-Meier analysis revealed survival free of component revision was 87% at 12 years (95% confidence interval, 84%-90%). The two most common indications for revision were ARMD (48%; 47 of 108 hips revised) and

Perthes' disease or late avascular necrosis after developmental dislocation of the hip? 10 children followed for 6-35 years.

PubMed

Koczewski, P; Napiontek, M

2001-08-01

We studied 10 patients treated because of late avascular necrosis (AVN) mimicking Legg-Calvé-Perthes' disease (LCPD) after developmental dislocation of the hip (DDH). DDH was recognized late at an average age of 5.4 months and in all children it was treated without surgery. In 4 children, the treatment was complicated by mild AVN of the femoral head, which had disappeared before 3 years of age. The first clinical signs of LCPD were noted at a mean age of 5.8 years. They all had Catterall's type III or IV of LCPD. The course was typical of LCPD. 8 children were operated on at mean age of 7.4 (5-12) years. In 7 of them, subtrochanteric derotation-varisation osteotomy of the femur with shortening combined mainly with Dega's pelvic osteotomy was done. The operative treatment resulted in a concentric position of the femoral head and good coverage of the acetabulum. Follow-ups were done at 10 (6-35) years. Shortened femoral neck and trochanteric overgrowth occurred in 4 operated hips. According to the Stulberg classification, 2 hips were classified as type I, 1 as I/II, 5 as II/I as II/III and 1 as IV. We conclude that LCPD mimicking late AVN can occur in hips treated because of developmental dislocation.

Posterior approach and dislocation rate: a 213 total hip replacements case-control study comparing the dual mobility cup with a conventional 28-mm metal head/polyethylene prosthesis.

PubMed

Bouchet, R; Mercier, N; Saragaglia, D

2011-02-01

Dislocation is a frequent complication of total hip arthroplasties (THA) especially in older patients, especially when using a posterior approach. In these cases, dual mobility (DM) cups developed by Gilles Bousquet in 1975 can be indicated to reduce this complication risk. Dual mobility cups reduce the rate of dislocation in primary total hip arthroplasty using posterior approach in a single-surgeon series. Test this hypothesis in a controlled study to compare the rate of dislocation in primary total hip arthroplasties done in patients over 50 years old either with a dual mobility cup or a conventional metal-on-polyethylene 28-mm diameter head. Two consecutive series of primary total hip replacements were performed by a single surgeon using a posterolateral approach. The piriformis tendon was left intact. The DM series included 105 patients who underwent arthroplasty between January 2005 and June 2007 with a dual mobility cup (60 women and 45 men, mean age 76.6±5.65 years old [53-93]). The control series (S series) included 108 patients who underwent arthroplasty (56 women and 52 men, mean age 74.2±5.9 years old [53-87]) with a conventional 28-mm polyethylene cup between January 2003 and June 2005. All hip replacements included a 28-mm metal-polyethylene cup and a 12-14-mm Morse taper. Both groups were comparable for gender, diagnosis, body mass index, type of anesthesia and ASA score distribution. All patients included in this series had a minimum follow-up of 1 year. There were no dislocations in the DM series and five early dislocations (before the third month) in the S series for a rate of 4.63%. Although the rate of dislocation was higher in the S series (4.63% vs 0%), the difference was barely significant (P=0.0597). This study comparing the incidence of dislocations after THA with conventional or dual mobility cups, shows that even using a posterior approach and in older patients, dual mobility cups increase stability with no postoperative dislocations

Patterns of postural deformity in non-ambulant people with cerebral palsy: what is the relationship between the direction of scoliosis, direction of pelvic obliquity, direction of windswept hip deformity and side of hip dislocation?

PubMed

Porter, David; Michael, Shona; Kirkwood, Craig

2007-12-01

To investigate: (a) associations between the direction of scoliosis, direction of pelvic obliquity, direction of windswept deformity and side of hip subluxation/ dislocation in non-ambulant people with cerebral palsy; and (b) the lateral distribution of these postural asymmetries. Cross-sectional observational study. Posture management services in three centres in the UK. Non-ambulant people at level five on the gross motor function classification system for cerebral palsy. Direction of pelvic obliquity and lateral spinal curvature determined from physical examination, direction of windswept hip deformity derived from range of hip abduction/adduction, and presence/side of unilateral hip subluxation defined by hip migration percentage. A total of 747 participants were included in the study, aged 6-80 years (median 18 years 10 months). Associations between the direction of scoliosis and direction of pelvic obliquity, and between the direction of windswept hip deformity and side hip subluxation/dislocation were confirmed. A significant association was also seen between the direction of scoliosis and the direction of the windswept hip deformity (P<0.001) such that the convexity of the lateral spinal curve was more likely to be opposite to the direction of windsweeping. Furthermore, significantly more windswept deformities to the right (P=0.007), hips subluxed on the left (P=0.002) and lateral lumbar/lower thoracic spinal curves convex to the left (P=0.03) were observed. The individual asymmetrical postural deformities are not unrelated in terms of direction and not equally distributed to the left/right. A pattern of postural deformity was observed.

Patterns of postural deformity in non-ambulant people with cerebral palsy: what is the relationship between the direction of scoliosis, direction of pelvic obliquity, direction of windswept hip deformity and side of hip dislocation?

PubMed Central

Michael, Shona; Kirkwood, Craig

2008-01-01

Objective: To investigate: (a) associations between the direction of scoliosis, direction of pelvic obliquity, direction of windswept deformity and side of hip subluxation/dislocation in non-ambulant people with cerebral palsy; and (b) the lateral distribution of these postural asymmetries. Design: Cross-sectional observational study. Setting: Posture management services in three centres in the UK. Subjects: Non-ambulant people at level five on the gross motor function classification system for cerebral palsy. Main measures: Direction of pelvic obliquity and lateral spinal curvature determined from physical examination, direction of windswept hip deformity derived from range of hip abduction/adduction, and presence/side of unilateral hip subluxation defined by hip migration percentage. Results: A total of 747 participants were included in the study, aged 6–80 years (median 18 years 10 months). Associations between the direction of scoliosis and direction of pelvic obliquity, and between the direction of windswept hip deformity and side hip subluxation/dislocation were confirmed. A significant association was also seen between the direction of scoliosis and the direction of the windswept hip deformity (P < 0.001) such that the convexity of the lateral spinal curve was more likely to be opposite to the direction of windsweeping. Furthermore, significantly more windswept deformities to the right (P = 0.007), hips subluxed on the left (P = 0.002) and lateral lumbar/lower thoracic spinal curves convex to the left (P = 0.03) were observed. Conclusions: The individual asymmetrical postural deformities are not unrelated in terms of direction and not equally distributed to the left/right. A pattern of postural deformity was observed. PMID:18042604

A Novel Approach for Dynamic Testing of Total Hip Dislocation under Physiological Conditions.

PubMed

Herrmann, Sven; Kluess, Daniel; Kaehler, Michael; Grawe, Robert; Rachholz, Roman; Souffrant, Robert; Zierath, János; Bader, Rainer; Woernle, Christoph

2015-01-01

Constant high rates of dislocation-related complications of total hip replacements (THRs) show that contributing factors like implant position and design, soft tissue condition and dynamics of physiological motions have not yet been fully understood. As in vivo measurements of excessive motions are not possible due to ethical objections, a comprehensive approach is proposed which is capable of testing THR stability under dynamic, reproducible and physiological conditions. The approach is based on a hardware-in-the-loop (HiL) simulation where a robotic physical setup interacts with a computational musculoskeletal model based on inverse dynamics. A major objective of this work was the validation of the HiL test system against in vivo data derived from patients with instrumented THRs. Moreover, the impact of certain test conditions, such as joint lubrication, implant position, load level in terms of body mass and removal of muscle structures, was evaluated within several HiL simulations. The outcomes for a normal sitting down and standing up maneuver revealed good agreement in trend and magnitude compared with in vivo measured hip joint forces. For a deep maneuver with femoral adduction, lubrication was shown to cause less friction torques than under dry conditions. Similarly, it could be demonstrated that less cup anteversion and inclination lead to earlier impingement in flexion motion including pelvic tilt for selected combinations of cup and stem positions. Reducing body mass did not influence impingement-free range of motion and dislocation behavior; however, higher resisting torques were observed under higher loads. Muscle removal emulating a posterior surgical approach indicated alterations in THR loading and the instability process in contrast to a reference case with intact musculature. Based on the presented data, it can be concluded that the HiL test system is able to reproduce comparable joint dynamics as present in THR patients.

A Novel Approach for Dynamic Testing of Total Hip Dislocation under Physiological Conditions

PubMed Central

Herrmann, Sven; Kluess, Daniel; Kaehler, Michael; Grawe, Robert; Rachholz, Roman; Souffrant, Robert; Zierath, János; Bader, Rainer; Woernle, Christoph

2015-01-01

Constant high rates of dislocation-related complications of total hip replacements (THRs) show that contributing factors like implant position and design, soft tissue condition and dynamics of physiological motions have not yet been fully understood. As in vivo measurements of excessive motions are not possible due to ethical objections, a comprehensive approach is proposed which is capable of testing THR stability under dynamic, reproducible and physiological conditions. The approach is based on a hardware-in-the-loop (HiL) simulation where a robotic physical setup interacts with a computational musculoskeletal model based on inverse dynamics. A major objective of this work was the validation of the HiL test system against in vivo data derived from patients with instrumented THRs. Moreover, the impact of certain test conditions, such as joint lubrication, implant position, load level in terms of body mass and removal of muscle structures, was evaluated within several HiL simulations. The outcomes for a normal sitting down and standing up maneuver revealed good agreement in trend and magnitude compared with in vivo measured hip joint forces. For a deep maneuver with femoral adduction, lubrication was shown to cause less friction torques than under dry conditions. Similarly, it could be demonstrated that less cup anteversion and inclination lead to earlier impingement in flexion motion including pelvic tilt for selected combinations of cup and stem positions. Reducing body mass did not influence impingement-free range of motion and dislocation behavior; however, higher resisting torques were observed under higher loads. Muscle removal emulating a posterior surgical approach indicated alterations in THR loading and the instability process in contrast to a reference case with intact musculature. Based on the presented data, it can be concluded that the HiL test system is able to reproduce comparable joint dynamics as present in THR patients. PMID:26717236

Dislocation and spontaneous reduction of the femoral implant against the femoral neck in an infected metal on metal hip resurfacing with complex collection.

PubMed

Tins, Bernhard

2011-07-01

Metal on metal resurfacing hip implants are known to have complications unique to this type of implant. The case presented adds a further previously not described complication, the dislocation and spontaneous reduction of the pin of the femoral component against the femoral neck. The radiographic and CT findings are demonstrated. The dislocation was aided by bone loss due to an infection with a large periarticular collection. Periarticular collections in hip resurfacings are often due to a hypersensitivity type reaction to metal debris. However in the case presented it was due to infection. MRI was not able to discern the infection from a sterile collection. CT demonstrated bone loss and periosteal reaction suggestive of infection. In addition calcification of the pseudocapsule was seen, this is not a recognized feature of sterile collections. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

[The hip joint in neuromuscular disorders].

PubMed

Strobl, W M

2009-07-01

Physiologic motor and biomechanical parameters are prerequisites for normal hip development and hip function. Disorders of muscle activity and lack of weight bearing due to neuromuscular diseases may cause clinical symptoms such as an unstable hip or reduced range of motion. Disability and handicap because of pain, hip dislocation, osteoarthritis, gait disorders, or problems in seating and positioning are dependent on the severity of the disease, the time of occurrence, and the means of prevention and treatment. Preservation of pain-free and stable hip joints should be gained by balancing muscular forces and by preventing progressive dislocation. Most important is the exact indication of therapeutic options such as movement and standing therapy as well as drugs and surgery.

A previously unreported, dominantly inherited syndrome of shortness of stature, ear malformations, and hip dislocation: the coxoauricular syndrome--autosomal or X-linked male-lethal.

PubMed

Duca, D; Pană, I; Ciovirnache, M; Simionesu, L; Ispas, I; Maxililian, C

1981-01-01

We reported an apparently previously undescribed syndrome, designated the coxoauricular syndrome, in a mother and her 3 daughters, all of whom shared in variable manner shortness of stature, minor vertebral and pelvic changes, dislocated hip(s), and microtia with corresponding hearing loss. The oldest daughter had coincidental Ullrich-Turner syndrome with 46, Xdel(X)(q 13) chromosome constitution. Inheritance of the trait in this family is dominant, either autosomal or X-linked, with hemizygote lethality.

Hip Dislocation and Dystocia in Early Medieval Times: Possible Evidence of Labor Maneuver.

PubMed

Malgosa, Assumpció; Carrascal, Susana; Piga, Giampaolo; Isidro, Albert

2016-12-01

In ancient times, maternal mortality would occur frequently, particularly during labor. Evidence of dystocia resulting in the death of a pregnant woman is very infrequent in paleopathologic literature, with only a few cases being demonstrated. In the early medieval site of Casserres, the skeleton of a young woman with a fetus in the pelvic region was found. Some abnormal findings of the maternal skeleton were evaluated, including a sacral anomaly, femoral head wound, the rare position of the lower left limb with the femoral head dislodged anteriorly and cephalad from the socket, and a fibular fracture. Examining the anomalies all together, a case of anterior hip dislocation related to a McRoberts-like maneuver performed during labor is a plausible explanation of the findings.

Analyses of outcomes of one-stage operation for treatment of late-diagnosed developmental dislocation of the hip: 864 hips followed for 3.2 to 8.9 years.

PubMed

Ning, Bo; Yuan, Yi; Yao, Jie; Zhang, Sichng; Sun, Jun

2014-11-28

The one-stage procedure for treatment of older developmental dislocation of the hip (DDH) is used widely. However, the best age group for this operation is still unknown. The aims of our study were to evaluate middle-term outcomes of one-stage surgical treatment of a large number of patients with late-diagnosed DDH, and to explore the best age group for treatment. We retrospectively reviewed 652 patients with a total of 864 hip joints with DDH, all aged >18 months. All the hip joints were treated with one-stage procedures including open reduction, pelvic osteotomy, and femoral shortening. The patients were divided into three groups according to age at surgery: Group I: 1.5-2.5 years; Group II: 2.5-8 years; and Group III: >8 years. The latest clinical and radiographic outcomes, complications and avascular necrosis (AVN) of the femoral head were evaluated and compared among the three groups. The mean age at surgery was 5.8 years (range: 1.5-13.2 years). The average time of follow-up was 6.2 years (range: 3.2-8.9 years). A total of 79.4% of good or excellent outcomes were obtained for clinical functional evaluation according to the McKay classification. For radiographic outcomes, 732 hips (84.7%) were classified as good or excellent according to the Severin classification. A total of 27.4% of all hips had a poor outcome according to the Kalamchi and MacEwen classification for AVN. The poorest outcomes were observed for clinical, radiographic and AVN results in Group III (p < 0.001). Compared with Group I, the better results for clinical and AVN outcomes were found in Group II (p < 0.001). However, similar clinical outcomes were observed between Groups I and II (p > 0.05). A significantly higher incidence of redislocation and residual acetabular dysplasia was observed in Tonnis grade II and III hip dislocation (p < 0.001). One-stage treatment of late-diagnosed DDH had a good outcome in young and middle group. Younger patients achieved better results

Hip arthroscopy using the lateral approach.

PubMed

Glick, J M

1988-01-01

The benefits of hip arthroscopy are apparent. It produces little postoperative morbidity and can be performed on an outpatient basis. The prompt recovery from the operation is also beneficial, particularly for elderly patients. Distraction of the hip by traction on a fracture table is necessary. Suggested indications for this procedure include synovectomy and synovial biopsy; removal of loose bodies; removal of debris after a closed reduction of a fracture-dislocation; evaluation and treatment of osteochondritis dissecans; evaluation for arthroplasty; and unresolved hip pain. Whether the lateral approach is useful in the following situations is yet to be explored: (1) Evaluation of pediatric conditions such as Legg-Perthes disease and congenital dislocated hip; (2) treatment of localized infection; (3) removal of entrapped methylmethacrylate in total hip replacement; and (4) reducing and fixating an acetabular fracture (M. Brennan, oral communication, April 6, 1987). Arthroscopy of the hip joint by the lateral approach is a valuable addition to the evaluation and treatment of hip disorders.

Could larger diameter of 4th generation ceramic bearing decrease the rate of dislocation after THA?

PubMed

Lee, Young-Kyun; Ha, Yong-Chan; Jo, Woo-Lam; Kim, Tae-Young; Jung, Woon-Hwa; Koo, Kyung-Hoi

2016-05-01

Fourth generation (Delta) ceramic bearing was developed to reduce dislocation after total hip arthroplasty (THA) by increasing the head diameter. We tested a hypothesis that 32/36 mm Delta ceramic bearing decreases the dislocation rate. We also evaluated ceramic-related complications and early outcome of this thin liner-on-large head ceramic bearing. We performed a prospective study on patients who underwent THA with use of 32/36 mm Delta ceramic bearing. The dislocation rate was compared with the historical dislocation rate of third generation 28 mm ceramic bearing. We also evaluated ceramic fracture, squeak, short-term results and survival. Follow-up period was minimum 2 years. Between April 2010 and February 2012, we enrolled 250 consecutive patients (278 hips). All patients received cementless prostheses. Four patients (4 hips) who received metal shells ≤ 46 mm and 28 mm heads were excluded. Three patients died and 2 patients were lost within 2 years. The remaining 241 patients (269 hips) were followed for 24-46 months. There were 142 men (161 hips) and 99 women (108 hips) with a mean age of 53.7 years (range, 17-75 years) at the index operation. Dislocation occurred in three hips (1.1%). An old age was a risk factor for dislocation. Ceramic fracture and squeaking did not occur in any patient. Mean Harris hip score was 90.3 points at the latest follow-up. All acetabular and femoral components had bone-ingrowth stability. No hip had detectable wear or osteolysis. The survival was 99.3% in the best case scenario and 97.8% in the worst at 48 months. Total hip arthroplasty with use of 32/36 mm Delta ceramic bearing showed lower incidence of hip dislocation compared with 28 mm third generation ceramic bearing. A caution should be paid to prevent a fall in senile patients even though a large head is used. The short-term results of THA with this type of ceramic articulation are encouraging and we did not find any ceramic-related complications. Copyright �

The rate of dislocation is not increased when minimal precautions are used after total hip arthroplasty using the posterolateral approach: a prospective, comparative safety study.

PubMed

Kornuijt, A; Das, D; Sijbesma, T; van der Weegen, W

2016-05-01

In order to prevent dislocation of the hip after total hip arthroplasty (THA), patients have to adhere to precautions in the early post-operative period. The hypothesis of this study was that a protocol with minimal precautions after primary THA using the posterolateral approach would not increase the short-term (less than three months) risk of dislocation. We prospectively monitored a group of unselected patients undergoing primary THA managed with standard precautions (n = 109, median age 68.9 years; interquartile range (IQR) 61.2 to 77.3) and a group who were managed with fewer precautions (n = 108, median age 67.2 years; IQR 59.8 to 73.2). There were no significant differences between the groups in relation to predisposing risk factors. The diameter of the femoral head ranged from 28 mm to 36 mm; meticulous soft-tissue repair was undertaken in all patients. The medical records were reviewed and all patients were contacted three months post-operatively to confirm whether they had experienced a dislocation. There were no dislocations in the less restricted group and one in the more restricted group (p = 0.32). For experienced surgeons using the posterolateral approach at THA and femoral heads of diameter ≥ 28 mm, it appears safe to manage patients in the immediate post-operative period with minimal precautions to protect against dislocation. Larger studies with adequate statistical power are needed to verify this conclusion. Experienced orthopaedic surgeons using the posterolateral approach for THA should not fear an increased dislocation rate if they manage their patients with a minimal precautions protocol. Cite this article: Bone Joint J 2016;98-B:589-94. ©2016 The British Editorial Society of Bone & Joint Surgery.

Tapered stems one-third proximally coated have higher complication rates than cylindrical two-third coated stems in patients with high hip dislocation undergoing total hip arthroplasty with step-cut shortening osteotomy.

PubMed

Ozden, V Emre; Dikmen, G; Beksac, B; Tozun, I Remzi

2017-06-01

The results of cementless stems in total hip arthroplasty (THA) done because of congenital dislocation with step-cut osteotomy is not well known, particularly the influence of the design and the role of extent of porous coating. Therefore we performed a retrospective study to evaluate the mid to long-term results THA performed with a single type acetabular component and different geometry and fixation type stems with ceramic bearings in the setting of step-cut subtrochanteric osteotomy in high hip dislocated (HHD) patients. We asked if the stem type affect the outcomes in terms of (1) intra and postoperative complication rates (2) radiographic outcomes (3) prosthesis survival in step-cut subtrochanteric shortening osteotomy. The type of the stem, whether cylindrical or tapered does not affect the outcome if the femoral canal fit and fill is obtained and the step-cut femoral shortening osteotomy is primarily fixed. Forty-five hips in 35 patients with a mean follow up of 10 years (range, 7-14 years) were evaluated. The single type cementless cup was placed at the level of the true acetabulum, a step-cut shortening femoral osteotomy was performed and reconstruction was performed with two different types of tapered stem in twenty-two hips (Synergy™ and Image™ proximally coated, Smith and Nephew, Menphis, TN, USA) and one type of cylindrical stem (Echelon™ with 2/3 coated, Smith and Nephew, Menphis, TN, USA) in twenty-three hips. Harris hip scores (HHS) and a University of California Los Angeles (UCLA) activity scores were calculated for all patients and successive X-rays were evaluated regarding component loosening and osteolysis, along with complications related to bearing, step-cut osteotomy and stem types. Forty-one hips (91%) had good and excellent clinical outcome according to HHS. The mean UCLA activity scores improved from 3.2±0.6 points (range, 2-4) preoperatively to 6.3 points±0.5 (range, 5-7) at the latest follow-up. The mean femoral shortening was 36

Comparison of dual-mobility cup and unipolar cup for prevention of dislocation after revision total hip arthroplasty.

PubMed

Gonzalez, Amanda Inez; Bartolone, Placido; Lubbeke, Anne; Dupuis Lozeron, Elise; Peter, Robin; Hoffmeyer, Pierre; Christofilopoulos, Panayiotis

2017-02-01

Background and purpose - Revision total hip arthroplasty (THA) is associated with higher dislocation rates than primary THA. We compared the risk of dislocation within 6 months and all-cause re-revision during the whole study period using either the dual-mobility cup or the unipolar cup. Methods - We used a prospective hospital registry-based cohort including all total and cup-only revision THAs performed between 2003 and 2013. The cups used were either dual-mobility or unipolar; the choice was made according to the preference of the surgeon. 316 revision THAs were included. The mean age of the cohort was 69 (25-98) years and 160 THAs (51%) were performed in women. The dual-mobility group (group 1) included 150 THAs (48%) and the mean length of follow-up was 31 (0-128) months. The unipolar group (group 2) included 166 THAs (53%) and the mean length of follow-up was 52 (0-136) months. Results - The incidence of dislocation within 6 months was significantly lower with the dual-mobility cup than with the unipolar cup (2.7% vs. 7.8%). The unadjusted risk ratio (RR) was 0.34 (95% CI: 0.11-1.02) and the adjusted RR was 0.28 (95% CI: 0.09-0.87). The number of patients needed to treat with a dual-mobility cup in order to prevent 1 case of dislocation was 19. The unadjusted incidence rate ratio for all-cause re-revision in the dual-mobility group compared to the unipolar group was 0.6 (95% CI: 0.3-1.4). Interpretation - Use of a dual-mobility rather than a unipolar cup in revision THA reduced the risk of dislocation within 6 months.

Screening for developmental dysplasia of the hip.

PubMed

Desprechins, B; Ernst, C; de Mey, J

2007-01-01

The reported prevalence of established dislocation the hip in an unscreened population varies from 0.7 to 1.6 / 1000 children in European and American white populations. In clinically screened populations neonatal hip instability is reported to occur in 3 to 30 / 1000 newborns while established congenital dislocation has a prevalence of 0.1- 4/1000 of which 1/1000 is judged to be in need for surgery. Early diagnosis of DDH is essential for successful treatment and later prognosis of the disorder. Combined procedure including evaluation of both hip morphology and hip stability is currently recommended. Opinions differ about the need for universal versus selective sonographic screening for diagnosis of DDH. Currently selective screening of those infants with recognised risk factors and those with abnormal physical examination would be cost-effective and the only practicable method for most countries.

[Intra-prosthetic dislocation of the Bousquet dual mobility socket].

PubMed

Lecuire, F; Benareau, I; Rubini, J; Basso, M

2004-05-01

The Bousquet system is a dual mobility head-polyethylene polyethylene-metal cup socket. The polyethylene insert retaining the femoral head moves in the noncemented metal cup, increasing both mobility and stability. Between 1989 and 1997, seven cases of intra-prosthetic dislocation (six patients) were observed. The femoral head escaped from the polyethylene insert due to wear. On the average, this complication occurred ten Years after implantation. Risk of dislocation was high in six of the seven hips. All patients had a large sized stem screwed into the femoral neck. There was a characteristic radiological aspect with loss of the concentric head metal cup configuration. The head was applied against the upper wall of the metal cup. Surgical replacement was undertaken early in six patients by simply changing the insert without modifying the other stable components. Outcome remained good at three to eight Years. One patient underwent late surgery. The insert and the cup were replaced with a classical implant. Functional outcome was good but recurrent dislocation occurred. At mid-term, intra-prosthetic dislocation of dual mobility sockets appears to be exceptional. Dislocation results from polyethylene wear leading to failure of the insert to retain the prosthetic head. Wear is favored by direct phenomena (direct contact between neck and insert which can occur early if there is a small difference in the head and neck diameters) or indirect phenomena (factors limiting polyethylene metal-cup mobility). Surgical treatment is necessary. If undertaken early, replacement with a modular head and insert can be sufficient if the prosthesis has not loosened but the metal cup may have to be replaced in the event of metal-metal contact between the head and the cup. Prosthesis loosening, wear of the metal cup, or an identified cause of dislocation imply replacing the failing implants. Implantation of the dual mobility system is particularly interesting for patients with a high risk

Lessons learned from study of congenital hip disease in adults.

PubMed

Hartofilakidis, George; Lampropoulou-Adamidou, Kalliopi

2016-12-18

Orthopaedic surgeons specialising in adult hip reconstruction surgery often face the problem of osteoarthritis secondary to congenital hip disease (CHD). To achieve better communication among physicians, better treatment planning and evaluation of the results of various treatment options, an agreed terminology is needed to describe the entire pathology. Furthermore, a generally accepted classification of the deformities is necessary. Herein, the authors propose the use of the term "congenital hip disease" and its classification as dysplasia, low dislocation and high dislocation. Knowledge of the CHD natural history facilitates comprehension of the potential development and progression of the disease, which differs among the aforementioned types. This can lead to better understanding of the anatomical abnormalities found in the different CHD types and thus facilitate preoperative planning and choice of the most appropriate management for adult patients. The basic principles for improved results of total hip replacement in patients with CHD, especially those with low and high dislocation, are: Wide exposure, restoration of the normal centre of rotation and the use of special techniques and implants for the reconstruction of the acetabulum and femur. Application of these principles during total hip replacement in young female patients born with severe deformities of the hip joint has led to radical improvement of their quality of life.

On the permanent hip-stabilizing effect of atmospheric pressure.

PubMed

Prietzel, Torsten; Hammer, Niels; Schleifenbaum, Stefan; Kaßebaum, Eric; Farag, Mohamed; von Salis-Soglio, Georg

2014-08-22

Hip joint dislocations related to total hip arthroplasty (THA) are a common complication especially in the early postoperative course. The surgical approach, the alignment of the prosthetic components, the range of motion and the muscle tone are known factors influencing the risk of dislocation. A further factor that is discussed until today is atmospheric pressure which is not taken into account in the present THA concepts. The aim of this study was to investigate the impact of atmospheric pressure on hip joint stability. Five joint models (Ø 28-44 mm), consisting of THA components were hermetically sealed with a rubber capsule, filled with a defined amount of fluid and exposed to varying ambient pressure. Displacement and pressure sensors were used to record the extent of dislocation related to intraarticular and ambient pressure. In 200 experiments spontaneous dislocations of the different sized joint models were reliably observed once the ambient pressure was lower than 6.0 kPa. Increasing the ambient pressure above 6.0 kPa immediately and persistently reduced the joint models until the ambient pressure was lowered again. Displacement always exceeded half the diameter of the joint model and was independent of gravity effects. This experimental study gives strong evidence that the hip joint is permanently stabilized by atmospheric pressure, confirming the theories of Weber and Weber (1836). On basis of these findings the use of larger prosthetic heads, capsular repair and the deployment of an intracapsular Redon drain are proposed to substantially decrease the risk of dislocation after THA. Copyright © 2014 Elsevier Ltd. All rights reserved.

The minimal invasive direct anterior approach in combination with large heads in total hip arthroplasty - is dislocation still a major issue? a case control study.

PubMed

Hoell, Steffen; Sander, Marius; Gosheger, Georg; Ahrens, Helmut; Dieckmann, Ralf; Hauschild, Gregor

2014-03-12

There have been increasing numbers of publications in recent years on minimally invasive surgery (MIS) for total hip arthroplasty (THA), reporting results with the use of different head sizes, tribologic and functional outcomes. This study presents the results and early complication rates after THA using the direct anterior approach (DAA) in combination with head sizes ≥ 36 mm. A total of 113 patients with THA were included in the study. The Harris Hip Score (HHS) was determined, a radiographic evaluation was carried out, and complications were recorded. The minimum follow-up period was 2 years (means 35 ± 7 months). The HHS improved from 43.6 (± 12) to 88.2 (± 14; P < 0.01). One early infection occurred, one periprosthetic fracture, and three cases of aseptic stem loosening. No incorrect positioning of the implants was observed, and there were no dislocations. THA with the minimally invasive DAA in combination with large heads is associated with good to very good functional results in the majority of cases. The complication rates are not increased. The rate of dislocation mainly as an complication of the first two years can be markedly reduced in particular.

Right upper limb bud triplication and polythelia, left sided hemihypertrophy and congenital hip dislocation, facial dysmorphism, congenital heart disease, and scoliosis: disorganisation-like spectrum or patterning gene defect?

PubMed

Sabry, M A; al-Saleh, Q; al-Saw'an, R; al-Awadi, S A; Farag, T I

1995-07-01

A Somali female baby with right upper limb triplication, polythelia, left sided hemihypertrophy, congenital hip dislocation, facial dysmorphism, congenital heart disease, and scoliosis is described. It seems that the above described pattern of anomalies has not been reported before. The possible developmental genetic mechanism responsible for this phenotype is briefly discussed.

Hip Surveillance in Children with Cerebral Palsy.

PubMed

Huser, Aaron; Mo, Michelle; Hosseinzadeh, Pooya

2018-04-01

The hip is the second most common involved joint in cerebral palsy. Hip displacement occurs in more than 33% of children with cerebral palsy, with a higher prevalence in nonambulatory children. Hip displacement in this population is typically progressive. Hip dislocation can result in pain and difficulty with sitting and perineal care. Since early stage of hip displacement can be silent, and hip surveillance programs are recommended. Most programs use the degree of hip dysplasia and Growth Motor Function Classification System level for screening recommendations. Treatment depends on the degree of dysplasia, functional status of the patient, and patient's age. Copyright © 2017 Elsevier Inc. All rights reserved.

Right upper limb bud triplication and polythelia, left sided hemihypertrophy and congenital hip dislocation, facial dysmorphism, congenital heart disease, and scoliosis: disorganisation-like spectrum or patterning gene defect?

PubMed Central

Sabry, M A; al-Saleh, Q; al-Saw'an, R; al-Awadi, S A; Farag, T I

1995-01-01

A Somali female baby with right upper limb triplication, polythelia, left sided hemihypertrophy, congenital hip dislocation, facial dysmorphism, congenital heart disease, and scoliosis is described. It seems that the above described pattern of anomalies has not been reported before. The possible developmental genetic mechanism responsible for this phenotype is briefly discussed. Images PMID:7562971

Gross Instability After Hip Arthroscopy: An Analysis of Case Reports Evaluating Surgical and Patient Factors.

PubMed

Yeung, Marco; Memon, Muzammil; Simunovic, Nicole; Belzile, Etienne; Philippon, Marc J; Ayeni, Olufemi R

2016-06-01

Gross hip instability is a rare complication after hip arthroscopy, and there is limited literature surrounding this topic. This systematic review investigates cases of gross hip instability after arthroscopy and discusses the risk factors associated with this complication. A systematic search was performed in duplicate for studies investigating gross hip instability after hip arthroscopy up to October 2015. Study parameters including sample size, mechanism and type of dislocation, surgical procedure details, patient characteristics, postoperative rehabilitation protocol, and level of evidence were analyzed. The systematic review identified 9 case reports investigating gross hip instability after hip arthroscopy (10 patients). Anterior dislocation occurred in 66.7% of patients, and most injuries occurred with a low-energy mechanism. Common surgical factors cited included unrepaired capsulotomy (77.8%) and iliopsoas release (33.3%), whereas patient factors included female gender (77.8%), acetabular dysplasia (22.2%), and general ligamentous laxity (11.1%). Postoperative restrictions and protocols were variable and inconsistently reported, and their relation to post-arthroscopy instability was difficult to ascertain. This systematic review discussed various patient, surgical, and postoperative risk factors of gross hip instability after arthroscopy. Patient characteristics such as female gender, hip dysplasia, and ligamentous laxity may be risk factors for post-arthroscopy dislocation. Similarly, surgical risk factors for iatrogenic hip instability may include unrepaired capsulotomies and iliopsoas debridement, although the role of capsular closure in iatrogenic instability is not clear. The influences of postoperative restrictions and protocols on dislocation are also unclear in the current literature. Surgeons should be cognizant of these risk factors when performing hip arthroscopy and be mindful that these factors appear to occur in combination. Level IV

A patient-specific model of the biomechanics of hip reduction for neonatal Developmental Dysplasia of the Hip: Investigation of strategies for low to severe grades of Developmental Dysplasia of the Hip.

PubMed

Huayamave, Victor; Rose, Christopher; Serra, Sheila; Jones, Brendan; Divo, Eduardo; Moslehy, Faissal; Kassab, Alain J; Price, Charles T

2015-07-16

A physics-based computational model of neonatal Developmental Dysplasia of the Hip (DDH) following treatment with the Pavlik Harness (PV) was developed to obtain muscle force contribution in order to elucidate biomechanical factors influencing the reduction of dislocated hips. Clinical observation suggests that reduction occurs in deep sleep involving passive muscle action. Consequently, a set of five (5) adductor muscles were identified as mediators of reduction using the PV. A Fung/Hill-type model was used to characterize muscle response. Four grades (1-4) of dislocation were considered, with one (1) being a low subluxation and four (4) a severe dislocation. A three-dimensional model of the pelvis-femur lower limb of a representative 10 week-old female was generated based on CT-scans with the aid of anthropomorphic scaling of anatomical landmarks. The model was calibrated to achieve equilibrium at 90° flexion and 80° abduction. The hip was computationally dislocated according to the grade under investigation, the femur was restrained to move in an envelope consistent with PV restraints, and the dynamic response under passive muscle action and the effect of gravity was resolved. Model results with an anteversion angle of 50° show successful reduction Grades 1-3, while Grade 4 failed to reduce with the PV. These results are consistent with a previous study based on a simplified anatomically-consistent synthetic model and clinical reports of very low success of the PV for Grade 4. However our model indicated that it is possible to achieve reduction of Grade 4 dislocation by hyperflexion and the resultant external rotation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Framing Hip Hop: New Methodologies for New Times

ERIC Educational Resources Information Center

Dimitriadis, Greg

2015-01-01

This article revisits the central impulse behind early advocacy for ethnographic approaches to hip hop--that critics should try as much as possible to limit their own certainties around what hip hop can and might mean. While ethnographic approaches can engender the kinds of personal dislocations that allow for this negotiation, they do not…

Outcomes of dual-mobility acetabular cup for instability in primary and revision total hip arthroplasty.

PubMed

Mohammed, Riazuddin; Hayward, Keith; Mulay, Sanjay; Bindi, Frank; Wallace, Murray

2015-03-01

The concept of a dual-mobility hip socket involves the standard femoral head component encased in a larger polyethylene liner, which in turn articulates inside a metal shell implanted in the native acetabulum. The aim of this study was to assess outcomes from using a Serf Novae(®) Dual Mobility Acetabular cup (Orthodynamics Ltd, Gloucestershire, UK) to address the problem of instability in primary and revision total hip arthroplasty (THA). A retrospective review was carried out of all hip arthroplasties performed in a District General Hospital utilising the dual-mobility socket from January 2007 to December 2012. Clinical and radiological outcomes were analysed for 44 hips in 41 patients, comprising 20 primary and 24 revision THA. The average age of the study group was 70.8 years (range 56-84 years) for primary and 76.4 years (range 56-89 years) for revision arthroplasty. Among the primary THA, always performed for hip osteoarthritis or in presence of osteoarthritic changes, the reasons to choose a dual mobility cup were central nervous system problems such as Parkinson's disease, stroke, dementia (10), hip fracture (5), failed hip fracture fixation (2), severe fixed hip deformity (2) and diffuse peripheral neuropathy (1). The indications for revisions were recurrent dislocation (17), aseptic loosening with abductor deficiency (4), failed hemiarthroplasty with abductor deficiency (2) and neglected dislocation (1). At a mean follow-up of 22 months (range 6-63 months), none of the hips had any dislocation, instability or infection and no further surgical intervention was required. Radiological assessment showed that one uncemented socket in a revision arthroplasty performed for recurrent dislocation had changed position, but was stable in the new position. The patient did not have complications from this and did not need any surgical intervention. Even though postoperative hip stability depends on several factors other than design-related ones, our study shows

Complication Rates for Hip Arthroscopy Are Underestimated: A Population-Based Study.

PubMed

Truntzer, Jeremy N; Hoppe, Daniel J; Shapiro, Lauren M; Abrams, Geoffrey D; Safran, Marc

2017-06-01

To identify major and minor complication rates associated with hip arthroscopy from a payer-based national database and compare with the rates reported in the existing literature. Patients who underwent hip arthroscopy between 2007 and 2014 were identified using PearlDiver, a publicly available database. Rates of major and minor complications, as well as conversion to total hip arthroscopy (THA), were determined by using Current Procedural Terminology (CPT) and International Classification of Diseases, Ninth Revision (ICD-9), codes. Incidence rates of select major complications across the entire database were used as a comparison group. Statistical significance was set at P < .05. Of 18 million patients screened from 2007 to 2014, a total of 2,581 hip arthroscopies were identified. The rates of major and minor complications within a 1-year postoperative period were 1.74% and 4.22%, respectively. Complications included heterotopic ossification (2.85%), bursitis (1.23%), proximal femur fracture (1.08%), deep vein thrombosis (0.79%), and hip dislocation (0.58%). The rate of conversion to THA within 1 year was 2.85%. When compared to rates in the general population, the relative risks [RRs] of requiring a THA (age <50 years, RR = 57.66, P < .001; age >50 years, RR = 22.05, P < .001), sustaining a proximal femur fracture (age <50 years, RR = 18.02, P < .001; age >50 years, RR = 2.23, P < .001), or experiencing a hip dislocation (RR 19.60, P < .001) at 1 year after hip arthroscopy were significantly higher in all age groups. Higher major complication rates after hip arthroscopy were observed using a national payer-based database than previously reported in the literature, especially in regard to hip dislocations and proximal femur fractures. Rates of total hip arthroplasty were similar to prior studies, whereas the rates of revision hip arthroscopy were higher. Level IV, case series. Copyright © 2017 Arthroscopy Association of North America. Published by

Evaluation and Referral for Developmental Dysplasia of the Hip in Infants.

PubMed

Shaw, Brian A; Segal, Lee S

2016-12-01

Developmental dysplasia of the hip (DDH) encompasses a wide spectrum of clinical severity, from mild developmental abnormalities to frank dislocation. Clinical hip instability occurs in 1% to 2% of full-term infants, and up to 15% have hip instability or hip immaturity detectable by imaging studies. Hip dysplasia is the most common cause of hip arthritis in women younger than 40 years and accounts for 5% to 10% of all total hip replacements in the United States. Newborn and periodic screening have been practiced for decades, because DDH is clinically silent during the first year of life, can be treated more effectively if detected early, and can have severe consequences if left untreated. However, screening programs and techniques are not uniform, and there is little evidence-based literature to support current practice, leading to controversy. Recent literature shows that many mild forms of DDH resolve without treatment, and there is a lack of agreement on ultrasonographic diagnostic criteria for DDH as a disease versus developmental variations. The American Academy of Pediatrics has not published any policy statements on DDH since its 2000 clinical practice guideline and accompanying technical report. Developments since then include a controversial US Preventive Services Task Force "inconclusive" determination regarding usefulness of DDH screening, several prospective studies supporting observation over treatment of minor ultrasonographic hip variations, and a recent evidence-based clinical practice guideline from the American Academy of Orthopaedic Surgeons on the detection and management of DDH in infants 0 to 6 months of age. The purpose of this clinical report was to provide literature-based updated direction for the clinician in screening and referral for DDH, with the primary goal of preventing and/or detecting a dislocated hip by 6 to 12 months of age in an otherwise healthy child, understanding that no screening program has eliminated late development or

Complications in Hip Arthroscopy

PubMed Central

Nakano, Naoki; Khanduja, Vikas

2016-01-01

Summary Background Recent developments in hip arthroscopic techniques and technology have made it possible in many cases to avoid open surgical dislocation for treating a variety of pathology in the hip. Although early reports suggest favourable results’ using hip arthroscopy and it has been shown to be a relatively safe procedure, complications do exist and can sometimes lead to significant morbidity. Methods This is a review article. The aim of this manuscript is to present the most frequent and/or serious complications that could occur at or following hip arthroscopy and some guidelines to avoid these complications. Conclusion Most complications of hip arthroscopy are minor or transient but serious complications can occur as well. A lot of complication e.g. acetabular labral puncture go unreported. Appropriate education and training, precise and meticulous surgical technique with correct instrumentation, the right indication in the right patient and adherence to advice from mentors and experienced colleagues are all essential factors for a successful outcome. Level of evidence: V. PMID:28066747

Clinical Results of Total Hip Arthroplasty in Two Patients with Charcot Hip Joints due to Congenital Insensivity to Pain with Anhydrosis

PubMed Central

Inoue, Daisuke; Kajino, Yoshitomo; Taga, Tadashi; Yamamoto, Takashi; Takagi, Tomoharu

2018-01-01

Traditionally, Charcot arthropathy has been considered an absolute contraindication for total hip arthroplasty (THA). However, some recent reports have shown that good short- to mid-term results can be achieved by improving the durability of the implant. This paper reports the mid- to long-term results of THA in two patients with Charcot hip joints caused by congenital insensivity to pain with anhydrosis. Both patients suffered multiple posterior dislocations in the six months immediately following surgery. However, with the continuous use of a hard abduction brace, one patient was eventually able to walk with a lofstrand cane and the other with the use of one crutch. Although one patient experienced a dislocation five years after surgery, X-rays taken after nine years and five years, respectively, revealed no clinical signs of implant loosening. We conclude that, with careful planning and appropriate precautions, THA may be a viable treatment option for Charcot hip joints caused by congenital insensivity to pain with anhydrosis. PMID:29666733

[Total hip arthroplasty in post-dysplastic hip arthritis. Can type and position of the acetabular component influence longevity of the prosthesis?].

PubMed

Fousek, J; Indráková, P

2007-02-01

The aim of the study was a retrospective evaluation of our patients with post-dysplastic hips treated by cemented or non-cemented total hip arthroplasty (THA) in order to ascertain which type and position of the acetabular component was most effective. In the years 1999-2002, 111 THA procedures were performed in 93 patients, 76 women and 17 men, with post-dysplastic hip arthritis. The average age of the patients at the time of implantation was 52.6 years. On the basis of pre-operative radiographic findings, the patients' conditions were evaluated using the Hartofilakidis classification into three disease categories: dysplasia, low dislocation and high dislocation, and the patients were placed in two groups. Group 1 included 78 patients, and group 2 comprised 26 patients. None of our patients was classified as having high dislocation. Thirty-nine of these patients had previously undergone surgery for dysplastic hips. A total of 104 THAs were evaluated, because radiographic data was incomplete in seven cases. In addition to X-ray findings, the prosthesis type (cemented, hybrid, non-cemented), post-operative complications and signs of loosening were included in the evaluation. Clinical outcomes were assessed by the Harris score. The follow-up terminating on 31st December 2005 was 67 months on the average. In group 1 patients, the average Harris score increased from 38.6 to 80.3 points and in group 2 patients from 35.5 to 84.9 points, mostly with excellent and good results. In 72.1 % of the hips, a press-fit acetabular component was implanted. In 55.8 % of the cases, the acetabular component was implanted off the anatomical center of rotation, into the high hip center, with the range from 9 to 20 mm and an average of 15 mm. The average limb lengthening was 2.5 cm, ranging from 1.0 to 3.5 cm. Our results show that it is more effective to use non-cemented THA for post-dysplastic hips. The implantation of a noncemented acetabular component into the high center provides

Hip resurfacing in patients under thirty years old: an attractive option for young and active patients.

PubMed

Krantz, Nicolas; Miletic, Bruno; Migaud, Henri; Girard, Julien

2012-09-01

Metal-on-metal hip resurfacing is offered as an alternative to traditional hip arthroplasty for young, active adults with advanced osteoarthritis. The concept of hip resurfacing is considered very attractive for this specific population (hard-on-hard bearing component with a large femoral head limiting the risk of dislocation, and allowing femoral bone stock preservation). A prospective clinical trial was designed to investigate the outcome of hip resurfacing in young patients (under 30 years old). We studied 24 hips in 22 patients. Mean age at operation was 24.9 years (range 17.1-29.9). No patient was lost to follow-up. There was no revision at average follow-up of 50.6 months (44-59). Mean UCLA activity score improved from 5.5 (1-9) pre-operatively to 7.6 (1-10) postoperatively (p < 0.001). Mean Harris hip score increased from 43.9 (19-67) to 89.3 (55-100) (p < 0.001). Radiological analysis discerned no osteolysis and no implant migration. The absence of short-term complications, such as mechanical failure or dislocation, is encouraging and leads us to think that mid-term results will be satisfactory. Moreover, the specific advantages of hip resurfacing (bone stock preservation, excellent stability, low risk of dislocation, large-diameter head) make the procedure a very attractive option for young subjects.

Femoroacetabular Impingement Is Associated With Sports-Related Posterior Hip Instability in Adolescents: A Matched-Cohort Study.

PubMed

Mayer, Stephanie W; Abdo, João Caetano Munhoz; Hill, Mary K; Kestel, Lauryn A; Pan, Zhaoxing; Novais, Eduardo N

2016-09-01

Femoroacetabular impingement (FAI) deformity has been associated with posterior hip instability in adult athletes. To determine if FAI deformity is associated with posterior hip instability in adolescents, the femoral head-neck junction or acetabular structure in a cohort of adolescent patients who sustained a low-energy, sports-related posterior hip dislocation was compared with that in a group of healthy age- and sex-matched controls with no history of hip injury or pain. Cross-sectional study; Level of evidence, 3. We identified 12 male patients (mean age, 13.9 years; range, 12-16 years) who sustained a sports-related posterior hip dislocation and underwent a computed tomography (CT) scan after closed reduction. For each patient, 3 age- and sex-matched healthy controls were identified. Femoral head-neck type was assessed by measurement of the alpha angle on the radially oriented CT images at the 12-, 1-, 2-, and 3-o'clock positions. Age, body mass index (BMI), alpha angle at each position, acetabular version, Tönnis angle, and lateral center-edge angle (LCEA) on the involved hip in the dislocation group were compared with those of the matched controls using a mixed-effects model. A logistic regression analysis using a generalized estimating equation was used to compare the percentage of subjects with cam-type FAI deformity (alpha angle >55°) in each group. The dislocation and control groups were similar in age distribution and BMI (P > .05). The mean alpha angles were statistically significantly higher in the dislocation group compared with the control group at the superior (46.3° ± 1.1° vs 42.7° ± 0.6°; P = .0213), superior-anterior (55.5° ± 1.9° vs 46.0° ± 1.3°; P = .0005), and anterior-superior (54.9° ± 1.5° vs 48.9° ± 1.0°; P = .0045) regions. Cam deformity was present in a larger proportion of patients in the dislocation group than in the control group (P < .0035). An alpha angle greater than 55° was present in 16.7% of the dislocation

[Effect of abducens orthosis combined with walker on developmental dysplasia of the hip].

PubMed

Hu, Zhiyong; Xu, Yongqiang; Liang, Jieyu; Li, Kanghua; Liao, Qiande

2009-07-01

To evaluate the effect of abducens orthosis combined with walker on developmental dysplasia of the hip (DDH). A total of 126 patients (224 hips) with DDH aged 6-36 months in Xiangya Hospital was randomly divided into 2 groups: an orthosis combined with walker group and an improved hip frog cast fixation group. Seventy patients (130 hips) were treated by the orthosis combined with walker and 56 patients (94 hips) were treated by the improved hip frog cast fixation. We compared the effect and complications of the 2 groups. The fineness rates of the orthosis combined with walker group and the improved hip frog cast fixation group were 89.2% and 90.4%, respectively, with no significant difference (P>0.05). The rate of femoral head osteonecrosis in the orthosis combined with walker group was significantly lower than that in the improved hip frog cast fixation group (1.5% vs. 5.3%,P<0.05), but the re-dislocation rate in the former was significantly higher than that in the latter (6.9% vs. 1.1 %, P<0.05). Both methods are effective for DDH. Orthosis combined with walker has a lower proportion of femoral head osteonecrosis, but a higher proportion of re-dislocation.

Dynamic behavior of tripolar hip endoprostheses under physiological conditions and their effect on stability.

PubMed

Fabry, Christian; Kaehler, Michael; Herrmann, Sven; Woernle, Christoph; Bader, Rainer

2014-01-01

Tripolar systems have been implanted to reduce the risk of recurrent dislocation. However, there is little known about the dynamic behavior of tripolar hip endoprostheses under daily life conditions and achieved joint stability. Hence, the objective of this biomechanical study was to examine the in vivo dynamics and dislocation behavior of two types of tripolar systems compared to a standard total hip replacement (THR) with the same outer head diameter. Several load cases of daily life activities were applied to an eccentric and a concentric tripolar system by an industrial robot. During testing, the motion of the intermediate component was measured using a stereo camera system. Additionally, their behavior under different dislocation scenarios was investigated in comparison to a standard THR. For the eccentric tripolar system, the intermediate component demonstrated the shifting into moderate valgus-positions, regardless of the type of movement. This implant showed the highest resisting torque against dislocation in combination with a large range of motion. In contrast, the concentric tripolar system tended to remain in varus-positions and was primarily moved after stem contact. According to the results, eccentric tripolar systems can work well under in vivo conditions and increase hip joint stability in comparison to standard THRs. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Cementless total hip arthroplasty with a double chevron subtrochanteric shortening osteotomy in patients with Crowe type-IV hip dysplasia.

PubMed

Li, Xigong; Sun, Junying; Lin, Xiangjin; Xu, Sanzhong; Tang, Tiansi

2013-06-01

The authors describe a modified double chevron subtrochanteric shortening osteotomy combined with cementless total hip arthroplasty for Crowe type-IV hip dysplasia. Shortening the femur allows to relax the shortened musculature. This operation was performed in 18 patients (22 hips) between January 2000 and February 2006. The mean follow-up period was 5.6 years (range: 3 to 8 years). The mean amount of femoral subtrochanteric shortening was 38 mm (range: 25 to 60 mm). The mean Harris hip score improved from 47 (range: 35 to 65) preoperatively to 88 points (range: 75 to 97) at final follow-up. The Trendelenburg sign was corrected from positive to negative in 12 of 22 hips. No acetabular or femoral components loosened or required revision during the follow-up period. All osteotomy sites healed in 3 to 6 months without complications. Cementless total hip arthroplasty using the modified double chevron subtrochanteric osteotomy provided good short- to midterm results in all 22 Crowe type-IV hip dislocations. Moreover, it restored the anatomic hip center and the limb length, which contributed to correction of the preoperative limp.

21 CFR 890.3665 - Congenital hip dislocation abduction splint.

Code of Federal Regulations, 2010 CFR

2010-04-01

... SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890... abduction splint is a device intended for medical purposes to stabilize the hips of a young child with...

[Efficacy analysis on hip replacement for hip-joint diseases with Parkinson disease].

PubMed

Sun, Qi-Cai; Ru, Xuan-Liang; Xia, Yan-Fei; Liu, Xiao-Li; Song, Bai-Shan; Qiao, Song; Yan, Shi-Gui; Wang, Xiang-Hua

2017-12-25

To explore clinical efficacy of hip replacement for hip-joint diseases with Parkinson disease. From December 2011 to December 2016, 18 patients with hip-joint diseases with Parkinson disease treated by hip replacement, including 8 males and 10 females aged from 59 to 87 years old with an average of 71 years old. Among them, 3 cases were developmental dysplasia of hip, 3 cases were femoral head necrosis and 12 cases were femoral neck fracture. All patients manifested with obvious pain and limitation of stepping ability. Postoperative complications were observed and Harris score were used to compare hip joint function after operation. The incision were healed well, and pain were alleviated or disappeared, and hip joint function were improved. Eighteen patients were followed up from 1 to 3 years with an average of 2.3 years. At the latest follow up, 14 cases recovered freedom-walk, 2 cases could walk with walking stick, 1 case could walk with walking aid and 1 case was died. Among 18 patients, 2 cases were occurred dislocation, and 1 case were died for cardiac disease at 3 months after operation. Four patients were occurred slight pain. There were significant differences in Harris scores among preoperative (41.7±1.4), 6 months after operation(80.1±5.4) and the final follow-up (83.4±2.1), and 10 cases got excellent result, 4 good, 1 fair and 2 poor. Application of hip replacement for hip-joint diseases with Parkinson disease is a safe and effective clinical therapy, and has advantages of less complications and rapid recovery of hip joint function.

Unconstrained tripolar hip implants: effect on hip stability.

PubMed

Guyen, Olivier; Chen, Qing Shan; Bejui-Hugues, Jacques; Berry, Daniel J; An, Kai-Nan

2007-02-01

Tripolar implants were developed to treat unstable total hip arthroplasties. However, there is limited confirmation that they achieve this purpose despite their increasing use. Because they have a larger effective head size, these implants are expected to increase range of motion to impingement and improve stability in situations at risk for impingement compared with conventional implants. We assessed the range of motion to impingement using a tripolar implant mounted to an automated hip simulator using 22.2-mm and 28-mm femoral head sizes. The 22 and 28-mm tripolar implants provided increases of 30.5 degrees in flexion, 15.4 degrees in adduction, and 22.4 degrees in external rotation compared with the conventional 22.2-mm femoral head diameter implant. At the critical position of 90 degrees hip flexion, there was an increase of 45.2 degrees in internal rotation. At 0 degrees and 30 degrees external rotation, extension increases were 18.8 degrees and 7.8 degrees, respectively. Bony impingement was the limiting factor. Tripolar implants increased the arc of motion before impingement in positions at risk for dislocation and are expected to provide greater stability.

Stability of the Giliberty bipolar hip: report of three cases.

PubMed

Langan, P; Weiss, C A

1978-01-01

The Giliberty Bipolar Hip Prosthesis consists of an unbonded acetabular cup which snap-fits over the head of the femoral prosthesis. Because of the free movement permitted at the cup-pelvic junction as well as at the snap-fit interface, there has been a great deal of concern over the potential for dislocation. Three patients in whom this unit was implanted sustained significant skeletal trauma subsequent to surgery. None of them dislocated. In each case the prosthetic head was known to be in a relatively vertical orientation with respect to the transverse axis of the pelvis prior to the injury. In 2 of the 3 cases radiographically identifiable movement of the cup was present before and after the injury. These observations suggest that the persistently mobile, vertically positioned unbonded cup remain stable despite the stress of significant trauma. It is probable that the potential for cup movement, even where on the X-ray it appears to have stopped, acts as a safety valve in absorbing force that might otherwise dislocate the hip or cause fractures of the femur or the pelvis.

[New classification of Crowe type IV developmental dysplasia of the hip].

PubMed

Ma, Hai-yang; Zhou, Yong-gang; Zheng, Chong; Cao, Wen-zhe; Wang Sen; Wu, Wen-ming; Piao, Shang; Du, Yin-qiao

2016-02-01

To compare differences between Crowe IV developmental dysplasia of the hip (DDH) with secondary acetabulum and Crowe IV DDH without secondary acetabulum,and determine whether it is necessary to divide Crowe IV DDH into two subtypes. From June 2007 to May 2015,145 hips of 112 Crowe N patients who underwent total hip arthroplasty (THA) using S-ROM stem were divided into two groups: secondary acetabulum formaton group (group A) and no secondary acetabulum formaton group (group B). In group A,there were 12 females, 96 males,with an average age of (39.38 ± 11.19) years old. In group B, there were 2 females, 35 males, with an average age of (38.19 ± 10.92) years old. All the patients were evaluated by using Harris Hip Score. Radiographic evaluations were made preoperatively and during follow up. The differences between two groups were compared on dislocation height, canal flare index (CFI), subtrochanteric shortening osteotomy (SSTO) usage, pre- and post-operation Harris scores, complications. The dislocation height for group A was (4.74 ± 1.57) cm, while the dislocation height for group B was (3.12 ± 1.15) cm. Significantly difference was detected between two groups. The CFI for group A was 2.69 ± 0.68, while the CFI for group B was 3.42 ± 0.79, and the significantly difference was detected between two groups. Harris scores were totally improved from 58.18 ± 15.67 preoperatively to 91.20 ± 3.79 post-operatively and the difference was significant. Pre-operative Harris scores was 58.1 ± 15.3 in group A, 58.3 ± 16.9 in group B. Post-operative Harris scores was 91.0 ± 4.1 in group A, 91.0 ± 5.1 in group B. No significant difference was found on Harris scores between A and B preoperatively and post-operatively. Complications of 4 cases peri-prosthesis fracture, 4 cases dislocation and 4 cases nerve injury occur in group A; While only one case dislocation and one case nerve injury occur in group B. No statistical significance was detected. Crowe IV DDH with

Preservation of the articular capsule and short lateral rotator in direct anterior approach to total hip arthroplasty.

PubMed

Kanda, Akio; Kaneko, Kazuo; Obayashi, Osamu; Mogami, Atsuhiko; Morohashi, Itaru

2018-03-09

In total hip arthroplasty via a direct anterior approach, the femur must be elevated at the time of femoral implant placement. For adequate elevation, division of the posterior soft tissues is necessary. However, if we damage and separate the posterior muscle tissue, we lose the benefits of the intermuscular approach. Furthermore, damage to the posterior soft tissue can result in posterior dislocation. We investigate that protecting the posterior soft tissue increases the joint stability in the early postoperative period and results in a lower dislocation rate. We evaluated muscle strength recovery by measuring the maximum width of the internal obturator muscle on CT images (GE-Healthcare Discovery CT 750HD). We compared the maximum width of the muscle belly preoperatively versus 10 days and 6 months postoperatively. As clinical evaluations, we also investigated the range of motion of the hip joint, hip joint function based on the Japanese Orthopaedic Association hip score (JOA score), and the dislocation rate 6 months after surgery. The width of the internal obturator muscle increased significantly from 15.1 ± 3.1 mm before surgery to 16.4 ± 2.8 mm 6 months after surgery. The JOA score improved significantly from 50.8 ± 15.1 points to 95.6 ± 7.6 points. No dislocations occurred in this study. We cut only the posterosuperior articular capsule and protected the internal obturator muscle to preserve muscle strength. We repaired the entire posterosuperior and anterior articular capsule. These treatments increase joint stability in the early postoperative period, thus reducing the dislocation rate. Therapeutic, Level IV.

Early results of one-stage correction for hip instability in cerebral palsy.

PubMed

Kim, Hui Taek; Jang, Jae Hoon; Ahn, Jae Min; Lee, Jong Seo; Kang, Dong Joon

2012-06-01

We evaluated the clinical and radiological results of one-stage correction for cerebral palsy patients. We reviewed clinical outcomes and radiologic indices of 32 dysplastic hips in 23 children with cerebral palsy (13 males, 10 females; mean age, 8.6 years). Ten hips had dislocation, while 22 had subluxation. Preoperative Gross Motor Function Classification System (GMFCS) scores of the patients were as follows; level V (13 patients), level IV (9), and level III (1). Acetabular deficiency was anterior in 5 hips, superolateral in 7, posterior in 11 and mixed in 9, according to 3 dimensional computed tomography. The combined surgery included open reduction of the femoral head, release of contracted muscles, femoral shortening varus derotation osteotomy and the modified Dega osteotomy. Hip range of motion, GMFCS level, acetabular index, center-edge angle and migration percentage were measured before and after surgery. The mean follow-up period was 28.1 months. Hip abduction (median, 40°), sitting comfort and GMFCS level were improved after surgery, and pain was decreased. There were two cases of femoral head avascular necrosis, but no infection, nonunion, resubluxation or redislocation. All radiologic indices showed improvement after surgery. A single event multilevel surgery including soft tissue, pelvic and femoral side correction is effective in treating spastic dislocation of the hip in cerebral palsy.

Nationwide multicenter follow-up cohort study of hip arthroplasties performed for osteonecrosis of the femoral head.

PubMed

Kobayashi, Seneki; Kubo, Toshikazu; Iwamoto, Yukihide; Fukushima, Wakaba; Sugano, Nobuhiko

2018-05-12

To identify modifiable factors related to post-operative dislocation and reoperation in patients with osteonecrosis of the femoral head (ONFH) in a large cohort. We studied 4995 hip arthroplasties: total hip arthroplasty (THA) was performed in 79% of patients; bipolar hemiarthroplasty (BP), 17%; total resurfacing arthroplasty (tRS), 3%; and hemi-resurfacing arthroplasty (hRS), 1%. A new type of BP (accounting for 49% of BPs) comprised a femoral component with a polished or smooth, small-diameter (approximately 10 mm) neck with a round or oval axial cut surface and no sharp corners. The infection rate was relatively low (0.56%) even though 58% of cases of ONFH were associated with systemic steroid use, a known risk factor for infection. Post-operative dislocation occurred in 4.3% of cases, with re-operation needed in 3.9%. The dislocation rate was related to surgery type: 5.2% in THA, 0.9% in BP, and 0% in tRS and hRS. Among total arthroplasties with six month or longer follow-up (3670 THAs and 159 tRSs), the risk factors for post-operative dislocation were younger (≤ 40 years) or older (≥ 62 years) age, higher body weight, posterolateral approach, and smaller prosthetic head diameter. Regarding the need for re-operation, higher body weight and surgery type were identified as risk factors. The relatively high dislocation rate of 5.2% in THA is a cause for concern. The identified risk factors for dislocation should be considered when selecting THA for treatment. Prosthesis survivorship in hRSs was inferior to that in BPs or THAs. Body weight also affected the survivorship of hip arthroplasties.

Outcome after cementless total hip arthroplasty for arthritic hip in patients with residual poliomyelitis: a case series.

PubMed

Cho, Yoon J; Lee, Choong H; Chun, Young S; Rhyu, Kee H

2016-09-29

In this case series, we investigated the outcome of cementless total hip arthroplasty (THA) for advanced hip osteoarthritis in patients with residual poliomyelitis to evaluate its clinical usefulness for these patients. 11 unilateral cementless primary THA were performed to arthritic hips in patients with residual poliomyelitis. 7 were in paralytic and 4 were in nonparalytic limbs. The mean follow-up duration was 79.9 months. Retrospective clinical evaluations with various scores and radiological evaluations were made. Harris Hip Score, Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Short-form (SF)-36 physical scales were significantly improved after the surgery. However, UCLA activity score and SF-36 mental scale were not. Because of remaining leg length discrepancies, all but 1 noted a residual limp. In nonparalytic hip, functional acetabular cup inclination during weight bearing significantly increased from installed inclination. Other than 1 case of posterior dislocation, no complications were observed. Although the overall result itself is excellent, THA for these patients cannot improve limp, physical activity and mental status. Surgeons should be aware of the change of the inclination of acetabular cup during mobilisation, especially for THA in contralateral hip.

The effect of soft tissue release of the hips on walking in myelomeningocele.

PubMed

Correll, J; Gabler, C

2000-06-01

Walking and standing capacity in myelomeningocele is highly dependent on the level of the neurological lesion. Deformities, mainly flexion deformities, of the hip can severely interfere with mobility. In a retrospective study, undertaken in our hospital, we evaluated the role of soft tissue release of the hip in patients with hip flexion contractures. A special surgical technique was performed in 55 hips. The results show a good effect on verticalization, even if the hip joints cannot be extended actively. A subluxated or dislocated hip did not influence the final outcome. During the mean follow-up of approximately 4 years, only a slight recurrence of the former deformity was observed. Most of the patients obtained great advantage from the operation.

Innovations in the management of hip fractures.

PubMed

Teasdall, Robert D; Webb, Lawrence X

2003-08-01

Hip fractures include fractures of the head, neck, intertrochanteric, and subtrochanteric regions. Head fractures commonly accompany dislocations. Neck fractures and intertrochanteric fractures occur with greatest frequency in elderly patients with a low bone mineral density and are produced by low-energy mechanisms. Subtrochanteric fractures occur in a predominantly strong cortical osseous region that is exposed to large compressive stresses. Implants used to address these fractures must accommodate significant loads while the fractures consolidate. Complications secondary to hip fractures produce significant morbidity and include infection, nonunion, malunion, decubitus ulcers, fat emboli, deep venous thrombosis, pulmonary embolus, pneumonia, myocardial infarction, stroke, and death.

[Analysis of the failures of a cemented constrained liner model in patients with a high dislocation risk].

PubMed

Gallart, X; Gomez, J C; Fernández-Valencia, J A; Combalía, A; Bori, G; García, S; Rios, J; Riba, J

2014-01-01

To evaluate the short-term results of an ultra high molecular weight polyethylene retentive cup in patients at high risk of dislocation, either primary or revision surgery. Retrospective review of 38 cases in order to determine the rate of survival and failure analysis of a constrained cemented cup, with a mean follow-up of 27 months. We studied demographic data, complications, especially re-dislocations of the prosthesis and, also the likely causes of system failure analyzed. In 21.05% (8 cases) were primary surgery and 78.95% were revision surgery (30 cases). The overall survival rate by Kaplan-Meier method was 70.7 months. During follow-up 3 patients died due to causes unrelated to surgery and 2 infections occurred. 12 hips had at least two previous surgeries done. It wasn't any case of aseptic loosening. Four patients presented dislocation, all with a 22 mm head (P=.008). Our statistical analysis didn't found relationship between the abduction cup angle and implant failure (P=.22). The ultra high molecular weight polyethylene retentive cup evaluated in this series has provided satisfactory short-term results in hip arthroplasty patients at high risk of dislocation. Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

Effect of cup inclination on predicted contact stress-induced volumetric wear in total hip replacement.

PubMed

Rijavec, B; Košak, R; Daniel, M; Kralj-Iglič, V; Dolinar, D

2015-01-01

In order to increase the lifetime of the total hip endoprosthesis, it is necessary to understand mechanisms leading to its failure. In this work, we address volumetric wear of the artificial cup, in particular the effect of its inclination with respect to the vertical. Volumetric wear was calculated by using mathematical models for resultant hip force, contact stress and penetration of the prosthesis head into the cup. Relevance of the dependence of volumetric wear on inclination of the cup (its abduction angle ϑA) was assessed by the results of 95 hips with implanted endoprosthesis. Geometrical parameters obtained from standard antero-posterior radiographs were taken as input data. Volumetric wear decreases with increasing cup abduction angle ϑA. The correlation within the population of 95 hips was statistically significant (P = 0.006). Large cup abduction angle minimises predicted volumetric wear but may increase the risk for dislocation of the artificial head from the cup in the one-legged stance. Cup abduction angle and direction of the resultant hip force may compensate each other to achieve optimal position of the cup with respect to wear and dislocation in the one-legged stance for a particular patient.

The breech presentation and the vertex presentation following an external version represent risk factors for neonatal hip instability.

PubMed

Andersson, J E; Odén, A

2001-08-01

The aim of this study was to evaluate the frequency and type of hip-joint instability and the frequency of hip dislocation requiring treatment in neonates who had been lying in the breech presentation and were delivered vaginally after an external version or by caesarean section, and to compare them with neonates who were naturally in the vertex presentation. Breech presentations without ongoing labour were subjected to an attempted external version and, in cases where this proved unsuccessful or where labour had started, to deliver by caesarean section. None of the breech presentations was vaginally delivered. The anterior-dynamic ultrasound method was used to assess the hip-joint status of the neonates. Out of 6,571 foetuses, 257 were in breech presentation after 36 wk of pregnancy. Sixty-two were vaginally delivered following an external version to vertex presentation and 195 were delivered by caesarean section, 75 of these following unsuccessful attempts to perform a version. Treatment for congenital hip-joint dislocation was performed on 0.2%. Out of the breech presentations, 1.0% of those delivered by caesarean section were treated, while in those with vaginal delivery following an external version the treatment frequency was 3.2%. No case of late diagnosed hip dislocation was recorded. Significant differences in frequency of hip-joint instability and treatment were found between (i) neonates delivered in breech presentation and those delivered with vertex presentation, (ii) infants delivered in vertex presentation, naturally or after successful version, and (iii) those delivered by caesarean section with or without attempted external version and those delivered with vortex presentation. Breech presentation predisposes to increased hip instability. The instability is present prior to delivery and is certainly not a primary result of delivery forces. Both breech and vertex presentations following an external or spontaneous version should be considered as risk

Disparity between Clinical and Ultrasound Examinations in Neonatal Hip Screening.

PubMed

Kyung, Bong Soo; Lee, Soon Hyuck; Jeong, Woong Kyo; Park, Si Young

2016-06-01

For early detection of developmental dysplasia of the hip (DDH), neonatal hip screening using clinical examination and/or ultrasound has been recommended. Although there have been many studies on the reliability of both screening techniques, there is still controversy in the screening strategies; clinical vs. selective or universal ultrasound screening. To determine the screening strategy, we assessed the agreement among the methods; clinical examination by an experienced pediatric orthopedic surgeon, sonographic morphology, and sonographic stability. From January 2004 to June 2009, a single experienced pediatric orthopedic surgeon performed clinical hip screenings for 2,686 infants in the neonatal unit and 43 infants who were referred due to impressions of hip dysplasia before 3 months of age. Among them, 156 clinically unstable or high-risk babies selectively received bilateral hip ultrasound examinations performed by the same surgeon using the modified Graf method. The results were analyzed statistically to detect any correlations between the clinical and sonographic findings. Although a single experienced orthopedic surgeon conducted all examinations, we detected only a limited relationship between the results of clinical and ultrasound examinations. Ninety-three percent of the clinically subluxatable hips were normal or immature based on static ultrasound examination, and 74% of dislocating hips and 67% of limited abduction hips presented with the morphology below Graf IIa. A total of 80% of clinically subluxatable, 42% of dislocating and 67% of limited abduction hips appeared stable or exhibited minor instability on dynamic ultrasound examination. About 7% of clinically normal hips were abnormal upon ultrasound examination; 5% showed major instability and 3% showed dysplasia above Graf IIc. Clinical stability had small coefficients between ultrasound examinations; 0.39 for sonographic stability and 0.37 for sonographic morphology. Between sonographic

Hip arthroscopy: prevalence of intra-articular pathologic findings after traumatic injury of the hip.

PubMed

Khanna, Vickas; Harris, Adam; Farrokhyar, Forough; Choudur, Hema N; Wong, Ivan H

2014-03-01

The purpose of this study was to document and compare the incidence of intra-articular hip pathologic findings identified using arthroscopy versus conventional imaging in patients with acute trauma to the hip. This was a blinded prospective case series study designed to review the incidence of intra-articular pathologic disorders in patients with post-traumatic injury between the ages of 18 and 65 years who were referred to a single surgeon. Injuries included hip dislocation, proximal femur fracture, pelvic ring fracture, acetabular fracture, penetrating injury (gunshot wound), and soft tissue injury. Preoperative radiographs, computed tomographic (CT) scans, or magnetic resonance imaging/magnetic resonance angiography (MRI/MRA) scans (or a combination of these) were obtained. Findings were documented and compared with intraoperative findings. A total of 29 post-traumatic hips were enrolled in this study. Hip arthroscopy identified 17 of 29 hips (59%) as having loose bodies, 11 of 29 (38%) hips as having an intra-articular step deformity, 14 of 29 (49%) hips as having an osteochondral lesion, and 27 of 29 (93%) hips as having a labral tear. Plain radiographs and CT scans yielded low sensitivity when compared with arthroscopy for the identification of loose bodies and step deformities. MRI/MRA comparison with arthroscopic findings suggest that MRI/MRA is an accurate tool for identification of labral tears, because 91% of tears seen on arthroscopy were also identified by MRI/MRA. In 4 hips, however, MRI/MRA failed to identify osteochondral lesions that were subsequently identified by arthroscopy. Traumatic injuries of the hip result in substantial intra-articular pathologic findings, including loose bodies, labral tears, step deformities, and osteochondral lesions. The arthroscope is a powerful tool in identifying these injuries. Plain radiographs and CT scans appear to underestimate the true incidence of loose bodies and step deformities within the joint when

A case report of the management and the outcome of a complete epiphyseal separation and dislocation with left anterior column fracture of the acetabulum.

PubMed

Palencia, Jesús; Alfayez, Saud; Serro, Firas; Alqahtani, Jamal; Alharbi, Hani; Alhinai, Hamed

2016-01-01

Femoral head and neck fractures in children are uncommon, accounting for fewer than 1% of all pediatric fractures and fewer than 8% of all hip fractures. Furthermore, traumatic transphyseal hip fracture is rare to present in daily practice especially when associated with an acetabular fracture. A twelve years old boy, not known to have any chronic illnesses, presented to the emergency department as a case of polytrauma after a road traffic accident. Signs of left hip dislocation were discovered upon physical examination. X-rays and CT scans, revealed a complete transphyseal posterior dislocation and a left anterior column fracture of the acetabulum with a minimal displacement. Within five hours, the patient underwent open reduction and internal fixation by two cannulated screws. The acetabular fracture was managed conservatively. After six months, there were clear signs of osteonecrosis of the femoral head. A high-energy trauma in children and adolescents can lead to simultaneous epiphyseal and acetabular fractures which are associated with a poor prognosis. The age seems to play a role as patients older than ten years have a higher risk of developing AVN after sustaining a hip dislocation regardless of the time of intervention. Epiphyseal fracture with dislocation of the femoral head is rare among children and adolescents, especially when associated with an acetabular fracture. AVN in such cases can develop, and it represents a challenge to orthopedic surgeons due to the poor prognosis and the future functional limitations of the joint. Copyright © 2016 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Acetabular-epiphyseal angle and hip dislocation in cerebral palsy: a preliminary study.

PubMed

Alí-Morell, O J; Zurita-Ortega, F; Davó-Jiménez, I; Segura-Biedma, S

To relate, in non-ambulatory subjects with palsy, Reimers' migration percentage with standardized radiological measurements, including the acetabular-epiphyseal angle. Descriptive, observational and transversal study of 15 individuals with cerebral palsy at levels IV and V of the Gross Motor Function Classification System, aged between 3 and 9 years. Radiological measurements of the acetabular index, Hilgenreiner's epiphyseal angle, acetabular-epiphyseal angle, neck-shaft angle and Reimers' migration percentage of each of the hips were performed. Correlations between acetabular index, epiphyseal angle and acetabular-epiphyseal angle were obtained with respect to the Reimers migration percentage. For hips with a migration rate of 15% or less, a positive correlation was observed between acetabular and epiphyseal angles. In our population, the measurement between acetabular and epiphyseal inclination represents the highest association with the hip migration percentage. Copyright © 2018 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

Socket position determines hip resurfacing 10-year survivorship.

PubMed

Amstutz, Harlan C; Le Duff, Michel J; Johnson, Alicia J

2012-11-01

Modern metal-on-metal hip resurfacing arthroplasty designs have been used for over a decade. Risk factors for short-term failure include small component size, large femoral head defects, low body mass index, older age, high level of sporting activity, and component design, and it is established there is a surgeon learning curve. Owing to failures with early surgical techniques, we developed a second-generation technique to address those failures. However, it is unclear whether the techniques affected the long-term risk factors. We (1) determined survivorship for hips implanted with the second-generation cementing technique; (2) identified the risk factors for failure in these patients; and (3) determined the effect of the dominant risk factors on the observed modes of failure. We retrospectively reviewed the first 200 hips (178 patients) implanted using our second-generation surgical technique, which consisted of improvements in cleaning and drying the femoral head before and during cement application. There were 129 men and 49 women. Component orientation and contact patch to rim distance were measured. We recorded the following modes of failure: femoral neck fracture, femoral component loosening, acetabular component loosening, wear, dislocation, and sepsis. The minimum followup was 25 months (mean, 106.5 months; range, 25-138 months). Twelve hips were revised. Kaplan-Meier survivorship was 98.0% at 5 years and 94.3% at 10 years. The only variable associated with revision was acetabular component position. Contact patch to rim distance was lower in hips that dislocated, were revised for wear, or were revised for acetabular loosening. The dominant modes of failure were related to component wear or acetabular component loosening. Acetabular component orientation, a factor within the surgeon's control, determines the long-term success of our current hip resurfacing techniques. Current techniques have changed the modes of failure from aseptic femoral failure to wear

[Total hip arthroplasty through anterior "minimal invasive" approach].

PubMed

Moerenhout, Kevin G; Cherix, Stéphane; Rüdiger, Hannes A

2012-12-19

Total hip replacement has seen a tremendous development and has become one of the most successful surgical interventions in orthopaedics. While during the first decades of development of total hip arthroplasty the fixation of the implant into the bone was the main concern, the focus has shifted towards surgical technique and soft tissue handling. In order to avoid permanent soft tissue damage, muscular dysfunction and concerns in regards to cosmetics, minimal invasive and anatomic approaches have been developed. We here provide a short overview on various methods of total hip replacements and we describe our technique through a minimal invasive direct anterior approach. While muscle and nerve damage is minimal, this technique allows for a rapid rehabilitation and is associated with an excellent functional outcome and a minimal risk for dislocation.

Overhead Bryant's Traction Does Not Improve the Success of Closed Reduction or Limit AVN in Developmental Dysplasia of the Hip.

PubMed

Sucato, Daniel J; De La Rocha, Adriana; Lau, Karlee; Ramo, Brandon A

2017-03-01

Preoperative Bryant's overhead traction before closed reduction (CR) in developmental dysplasia of the hip (DDH) remains controversial and its success in increasing CR rates and reducing avascular necrosis (AVN) rates has not been specifically reported in a large cohort. IRB-approved retrospective study of patients (below 3 y)who were treated with attempted CR for idiopathic DDH from 1980 to 2009. Successful CR was defined as a hip that remained reduced and did not require repeat CR or open reduction. Patients were grouped by age, hip instability [Ortolani positive (reducible) vs. fixed dislocation], and Tonnis classification and rates of successful CR were compared between groups with P<0.05. A total of 342 hips were included with a mean age of 0.9 years (0.2 to 2.8 y) and a mean follow-up of 10.4 years (2.0 to 27.7 y). There were 269 hips with fixed dislocations and 73 Ortolani-positive hips. Traction was used in 276 hips. There was no difference in traction utilization in the 3 age groups (below 1, below 1.5, and below 2 y) for either Ortolani-positive hips (P=0.947) or fixed dislocations (P=0.943). There was no difference in achieving a successful CR comparing traction (60.9%) and no-traction groups (60.6%) (P=1.00). For Ortolani-positive hips, traction did not improve the incidence of a successful CR for any age group: below 1 year: P=0.19; below 1.5 years: P=0.23; and below 2 years: P=0.25. Similarly, fixed dislocation patients had no benefit from traction: below 1 year: P=0.76; below 1.5 years: P=0.82; and below 2 years: P=0.85. Tonnis classification did predict success of CR but had no influence on traction success. There was no difference in the rate of AVN between the traction (18%) and no-traction (8%) groups for all patients (P=0.15). In this retrospective series, preoperative Bryant's traction does not improve the rate of a successful CR for patients with DDH and has no protective effect on the development of AVN of the femoral head. These results

Current Concepts in Hip Preservation Surgery

PubMed Central

Adler, Kelly L.; Cook, P. Christopher; Geisler, Paul R.; Yen, Yi-Meng; Giordano, Brian D.

2016-01-01

Context: Successful treatment of nonarthritic hip pain in young athletic individuals remains a challenge. A growing fund of clinical knowledge has paralleled technical innovations that have enabled hip preservation surgeons to address a multitude of structural variations of the proximal femur and acetabulum and concomitant intra-articular joint pathology. Often, a combination of open and arthroscopic techniques are necessary to treat more complex pathomorphologies. Peri- and postoperative recovery after such procedures can pose a substantial challenge to the patient, and a dedicated, thoughtful approach may reduce setbacks, limit morbidity, and help optimize functional outcomes. Evidence Acquisition: PubMed and CINAHL databases were searched to identify relevant scientific and review articles through December 2014 using the search terms hip preservation, labrum, surgical dislocation, femoroacetabular impingement, postoperative rehabilitation, peri-acetabular osteotomy, and rotational osteotomy. Reference lists of included articles were reviewed to locate additional references of interest. Study Design: Clinical review. Level of Evidence: Level 4. Results: Hip preservation procedures and appropriate rehabilitation have allowed individuals to return to a physically active lifestyle. Conclusion: Effective postoperative rehabilitation must consider modifications and precautions specific to the particular surgical techniques used. Proper postoperative rehabilitation after hip preservation surgery may help optimize functional recovery and maximize clinical success and patient satisfaction. PMID:26733593

Primary total hip replacement for displaced subcapital fractures of the femur.

PubMed

Taine, W H; Armour, P C

1985-03-01

The management of displaced subcapital fracture of the hip is still controversial because of the high incidence of complications after internal fixation or hemiarthroplasty. To avoid some of these complications we have used primary total hip replacement for independently mobile patients over 65 years of age. A total of 163 cases, operated on over four years, have been reviewed. There were relatively more dislocations after operation for fracture than after total replacement for arthritis, and these were associated with a posterior approach to the hip. Only seven revision operations have been required. Of 57 patients who were interviewed an average of 42 months after replacement, 62% had excellent or good results as assessed by the Harris hip score. All the others had major systemic disease which affected their assessment. This inadequacy of current systems of hip assessment is discussed. It is concluded that total hip replacement is the best management for a selected group of patients with this injury, and that further prospective studies are indicated.

Developmental dysplasia of the hip: addressing evidence gaps with a multicentre prospective international study.

PubMed

Schaeffer, Emily K; Study Group, Ihdi; Mulpuri, Kishore

2018-05-07

There is a lack of high quality evidence available to guide clinical practice in the treatment and management of developmental dysplasia of the hip (DDH). Evidence has been limited by persistent confusion on diagnostic and classification terminology, variability in surgeon decision making and a reliance on single centre, retrospective studies with small patient numbers. To address gaps in knowledge regarding screening, diagnosis and management of DDH, the International Hip Dysplasia Institute began a multicentre, international prospective study on infants with hips dislocated at rest. This review discusses the current state of screening, diagnostic and management practices in DDH and addresses important unanswered questions that will be critical in identifying best practices and optimising patient outcomes. There is insufficient evidence to support universal ultrasound screening; instead, selective screening should be performed by 6-8 weeks of age on infants with risk factors of breech presentation, family history, or history of clinical hip instability. Follow-up of infants with risk factors and normal initial screening should be considered to at least 6 months of age. Brace treatment is a sensible first-line treatment for management of dislocated hips at rest in infants < 6 months of age. Early operative reduction may be considered as there is insufficient evidence to support a protective role for the ossific nucleus in the development of avascular necrosis.

Dual Mobility Cemented Cups Have Low Dislocation Rates in THA Revisions

PubMed Central

Langlais, Frantz L.; Gaucher, François; Musset, Thierry; Chaix, Olivier

2008-01-01

THA revisions using standard cups are at risk of dislocation (5.1% to 14.4% incidence), especially in patients over 70 years of age. Constrained tripolar cups have reduced this risk (6% incidence) but are associated with substantial loosening rates (9%). The nonconstrained dual mobility cup was designed to improve prosthetic stability (polyethylene head ≥ 40 mm diameter) without increasing loosening rates by reducing wear and limiting impingement (rotation range of 108°). We implanted 88 cemented dual mobility cups for THA revisions in 82 patients at high risk of dislocation. Average patient age was 72 years (range, 65–86 years). Eighty-five of the 88 hips were reviewed at 2 to 5 years followup. One patient (1.1%) had a traumatic dislocation at 2 years postoperatively. Two patients (2.3%) had asymptomatic early loosening and three patients (3.5%) had localized radiographic lucencies. These results confirm those with press-fit dual mobility cups suggesting a low dislocation rate at 5 years and a cup survival of 94.6%. At middle term followup, cemented dual mobility cup achieved better results than constrained cups in cases at risk of dislocation and recurrent loosening. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18196422

Total hip arthroplasty performed in patients with residual poliomyelitis: does it work?

PubMed

Yoon, Byung-Ho; Lee, Young-Kyun; Yoo, Jeong Joon; Kim, Hee Joong; Koo, Kyung-Hoi

2014-03-01

Patients with residual poliomyelitis can have advanced degenerative arthritis of the hip in the paralytic limb or the nonparalytic contralateral limb. Although THA is a treatment option for some of these patients, there are few studies regarding THA in this patient population. We therefore reviewed a group of patients with residual poliomyelitis who underwent cementless THA on either their paralytic limb or nonparalytic limb to assess (1) Harris hip scores, (2) radiographic results, including implant loosening, (3) complications, including dislocation, and (4) limb length discrepancy after recovery from surgery. From January 2000 to December 2009, 10 patients with residual poliomyelitis (10 hips, four paralytic limbs and six nonparalytic contralateral limbs) underwent THA using cementless prostheses. Harris hip scores, complications, and leg length discrepancy were determined by chart review, and confirmed by questionnaire and examination; radiographs were reviewed by two observers for this study. Followup was available for all 10 patients at a minimum of 3 years (median, 7 years; range, 3.4-13 years). Surgery was done at the same side of the paralytic limb in four hips and contralateral to the paralytic limb in six. All patients had pain relief and improvement in function; the Harris hip score improved from mean of 68 preoperatively to 92 at last followup (p = 0.043). However, only three patients had complete pain relief. One hip dislocated, which was treated successfully with closed reduction and a hip spica cast for 2 months. There was no loosening or osteolysis in this series. Leg length discrepancy improved after the index operation, but only in the THAs performed in the paralytic limbs. Cementless THA may be suitable for painful hips in adult patients with residual poliomyelitis. Nonetheless, these patients should be informed of the possibility of mild residual pain and persistent leg length discrepancy, particularly patients whose THA is performed on the

[Dislocated fracture of the lesser trochanter with malrotation of the stem after robot assisted implantation of a cementless hip prosthesis: a casuistic report].

PubMed

Prymka, M; Hassenpflug, J

2003-08-01

This paper presents the case of a 63 year old female with a severe coxarthrosis. She got a robot assited implantation of a cementless hip prosthesis (Osteolock, Stryker-Howmedica, Mühlheim). As operation robot the CASPAR-System (Orto-Maquet, Rastatt) was used. Initially, the clinical progress of the patient was fine. She was nearly painfree within 14 days and showed an acceptable range of motion in the operated joint (flexion/ extension 90 degrees /05 degrees /00 degrees ). She was mobilized with crutches and 15 kg weight bearing at the operated leg. 3 weeks postoperative the patient complaint about increasing pain without trauma or intensification of the weight bearing. X-rays showed not only a dislocated fracture of the lesser trochanter, but also a sinking combined with a malrotation of the stem. A revision operation was necessary,where we implanted a cemented stem. Now clinical progress was completely satisfying.

Use of a Dual Mobility Socket to Manage Total Hip Arthroplasty Instability

PubMed Central

Pibarot, Vincent; Vaz, Gualter; Chevillotte, Christophe; Béjui-Hugues, Jacques

2008-01-01

Unconstrained tripolar hip implants provide an additional bearing using a mobile polyethylene component between the prosthetic head and the outer metal shell. Such a design increases the effective head diameter and therefore is an attractive option in challenging situations of unstable total hip arthroplasties. We report our experience with 54 patients treated using this dual mobility implant in such situations. We ascertained its ability to restore and maintain stability, and examined component loosening and component failure. At a minimum followup of 2.2 years (mean, 4 years; range, 2.2–6.8 years), one hip had redislocated 2 months postoperatively and was managed successfully without reoperation by closed reduction with no additional dislocation. Two patients required revision of the implant because of dislocation at the inner bearing. Technical errors were responsible for these failures. Three patients had reoperations for deep infections. The postoperative radiographs at latest followup showed very satisfactory osseointegration of the acetabular component because no radiolucent line or osteolysis was reported. Use of this unconstrained tripolar design was successful in restoring and maintaining hip stability. We observed encouraging results at short-term followup regarding potential for loosening or mechanical failures. Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. PMID:18780135

Conversion of hip fusion to total hip arthroplasty: clinical, radiological outcomes and complications in 40 hips.

PubMed

Celiktas, Mustafa; Kose, Ozkan; Turan, Adil; Guler, Ferhat; Ors, Cagri; Togrul, Emre

2017-01-01

heterotopic ossification, sciatic nerve palsy or dislocation. There were five intra-operative fractures of the greater trochanter that were treated with cable wiring. One patient had trochanteric avulsion injury and was treated with trochanteric grip and cables. One patient (2.5%) had deep infection one year after the conversion THA and was treated with two-staged exchange procedure. Conversion hip arthroplasty is an effective treatment method which provides functional recovery and patient satisfaction. However, a proper surgical technique and planning is necessary to minimize the complications.

Assessment of Diagnostic Value of Single View Dynamic Technique in Diagnosis of Developmental Dysplasia of Hip: A Comparison with Static and Dynamic Ultrasond Techniques

PubMed Central

Alamdaran, Seyed Ali; Kazemi, Sahar; Parsa, Ali; Moghadam, Mohammad Hallaj; Feyzi, Ali; Mardani, Reza

2016-01-01

Background: Developmental dysplasia of hip (DDH) is a common childhood disorder, and ultrasonography examination is routinely used for screening purposes. In this study, we aimed to evaluate a modified combined static and dynamic ultrasound technique for the detection of DDH and to compare with the results of static and dynamic ultrasound techniques. Methods: In this cross-sectional study, during 2013- 2015, 300 high-risk infants were evaluated by ultrasound for DDH. Both hips were examined with three techniques: static, dynamic and single view static and dynamic technique. Statistical analysis was performed using SPSS version 11.5. Results: Patients aged 9 days to 83 weeks. 75% of the patients were 1 to 3 months old. Among 600 hip joints, about 5% were immature in static sonography and almost all of them were unstable in dynamic techniques. 0.3% of morphologically normal hips were unstable in dynamic sonography and 9% of unstable hips had normal morphology. The mean β angle differences in coronal view before and after stress maneuver was 14.43±5.47° in unstable hips. Single view static and dynamic technique revealed that all cases with acetabular dysplasia, instability and dislocation, except two dislocations, were detected by dynamic transverse view. For two cases, Ortolani maneuver showed femoral head reversibility in dislocated hips. Using single view static and dynamic technique was indicative and applicable for detection of more than 99% of cases. Conclusion: Single view static and dynamic technique not only is a fast and easy technique, but also it is of high diagnostic value in assessment of DDH. PMID:27847852

Design of a hip prosthetic tribometer based on salat gait cycle

NASA Astrophysics Data System (ADS)

Towijaya, T.; Ismail, R.; Jamari, J.

2017-01-01

Indonesia is the country with the largest muslim population in the world, most of the inhabitants do salat every day. THR (Total Hip Replacement) patients are prohibited from doing salat in normal gait. It leads to the damage of the hip joint prostheses due to impingement and dislocation.This paper reports the design of a pin-on-ring tribometer which is used to measure and analyze the wear volume and the impingement of hip joint prostheses during salat. The modifications of the femoral head and acetabular cup holder are performed to design the reciprocating motion for the movement of the hip prostheses. The interesting finding of the present research is a new mechanism of linked-bar which leads to the feasibility of the measurement of the wear volume and the impingement for THR patients during salat.

Adventure sports and sexual freedom hip replacement: the tripolar hip.

PubMed

Pritchett, James W

2018-01-01

Certain athletic activities and lifestyles require a completely stable and very mobile hip. Total hip replacement with a natural femoral head size and two mobile-bearing surfaces (i.e., a "tripolar" prosthesis) is the most stable prosthesis. Elegant design and wear-resistant bearing surfaces are the keys to long-term implant survivorship. The hypothesis is that a ceramic-coated tripolar prosthesis using highly cross-linked polyethylene can provide full function and complete stability with low wear. This study sought to determine: (1) patient-reported outcomes, (2) functional outcomes, (3) implant survivorship and complications, and (4) postoperative sexual limitations. Between 1998 and 2011, the author performed 160 primary total hip replacements using tripolar prostheses in patients participating in adventure sports and other physically demanding activities. The institutional review board approved this study. The inclusion criteria were patients who needed unrestricted activity and who were not candidates for or did not choose hip resurfacing. Patients were followed every second year and assessed with radiographs, Harris Hip Score, WOMAC, SF-12, and UCLA functional outcome scores. Patients were asked about symptoms of instability and satisfaction with their hip replacement. Patients were asked both preoperatively and 2 years postoperatively four questions about their sexual activity. Mean follow-up was 11 years. At 2 years' postoperatively, 98% of patients reported their satisfaction as excellent or good and 99% were not limited for sexual activity following surgery. Seventy-four percent of patients reported they were recovered within 6 weeks of surgery. There were no dislocations. There were three revision procedures for implant loosening, infection, and periprosthetic fracture, but there were no failures of the tripolar articulation. The mean postoperative UCLA score was the highly athletic score of 8. There were no signs of osteolysis, wear, or metal

Medial versus anterior open reduction for developmental hip dislocation in age-matched patients.

PubMed

Hoellwarth, Jason S; Kim, Young-Jo; Millis, Michael B; Kasser, James R; Zurakowski, David; Matheney, Travis H

2015-01-01

The difference between medial (MAOR) and anterior (AAOR) approaches for open reduction of developmental hip dysplasia in terms of risk for avascular necrosis (AVN) and need for further corrective surgery (FCS, femoral and/or acetabular osteotomy) is unclear. This study compared age-matched cohorts undergoing either MAOR or AAOR in terms of these 2 primary outcomes. Prognostic impact of presence of ossific nucleus at time of open reduction was also investigated. Institutional review board approval was obtained. Nineteen hips (14 patients) managed by MAOR were matched with 19 hips (18 patients) managed by AAOR based on age at operation (mean 6.0; range, 1.4 to 14.9 mo). Patients with neuromuscular conditions and known connective tissue disorders were excluded. Primary outcomes assessed at minimum 2 years' follow-up included radiographic evidence of AVN (Kalamchi and MacEwen) or requiring FCS. MAOR and AAOR cohorts were similar regarding age at open reduction, sex, laterality, and follow-up duration. One hip in each group had AVN before open reduction thus were excluded from AVN analysis. At minimum 2 years postoperatively (mean 6.2; range, 1.8 to 11.7 y), 4/18 (22%) MAOR and 5/18 (28%) AAOR met the same criteria for AVN (P=1.0). No predictors of AVN could be identified by regression analysis. Presence of an ossific nucleus preoperatively was not a protective factor from AVN (P=0.27). FCS was required in 4/19 (21%) MAOR and 7/19 (37%) AAOR hips (P=0.48). However, 7/12 (54%) hips failing closed reduction required FCS compared with 4/26 (16%) hips without prior failed closed reduction (P=0.024). Cox regression analysis showed that patients who failed closed reduction had an annual risk of requiring FCS approximately 6 times that of patients without a history of failed closed reduction (hazard ratio=6.1; 95% CI, 1.5-24.4; P=0.009), independent of surgical approach (P=0.55) or length of follow-up (P=0.78). In this study of age-matched patients undergoing either MAOR or

The Impact of Lumbar Spine Disease and Deformity on Total Hip Arthroplasty Outcomes.

PubMed

Blizzard, Daniel J; Sheets, Charles Z; Seyler, Thorsten M; Penrose, Colin T; Klement, Mitchell R; Gallizzi, Michael A; Brown, Christopher R

2017-05-01

Concomitant spine and hip disease in patients undergoing total hip arthroplasty (THA) presents a management challenge. Degenerative lumbar spine conditions are known to decrease lumbar lordosis and limit lumbar flexion and extension, leading to altered pelvic mechanics and increased demand for hip motion. In this study, the effect of lumbar spine disease on complications after primary THA was assessed. The Medicare database was searched from 2005 to 2012 using International Classification of Diseases, Ninth Revision, procedure codes for primary THA and diagnosis codes for preoperative diagnoses of lumbosacral spondylosis, lumbar disk herniation, acquired spondylolisthesis, and degenerative disk disease. The control group consisted of all patients without a lumbar spine diagnosis who underwent THA. The risk ratios for prosthetic hip dislocation, revision THA, periprosthetic fracture, and infection were significantly higher for all 4 lumbar diseases at all time points relative to controls. The average complication risk ratios at 90 days were 1.59 for lumbosacral spondylosis, 1.62 for disk herniation, 1.65 for spondylolisthesis, and 1.53 for degenerative disk disease. The average complication risk ratios at 2 years were 1.66 for lumbosacral spondylosis, 1.73 for disk herniation, 1.65 for spondylolisthesis, and 1.59 for degenerative disk disease. Prosthetic hip dislocation was the most common complication at 2 years in all 4 spinal disease cohorts, with risk ratios ranging from 1.76 to 2.00. This study shows a significant increase in the risk of complications following THA in patients with lumbar spine disease. [Orthopedics. 2017; 40(3):e520-e525.]. Copyright 2017, SLACK Incorporated.

The Cost-Effectiveness of Dual Mobility Implants for Primary Total Hip Arthroplasty: A Computer-Based Cost-Utility Model.

PubMed

Barlow, Brian T; McLawhorn, Alexander S; Westrich, Geoffrey H

2017-05-03

Dislocation remains a clinically important problem following primary total hip arthroplasty, and it is a common reason for revision total hip arthroplasty. Dual mobility (DM) implants decrease the risk of dislocation but can be more expensive than conventional implants and have idiosyncratic failure mechanisms. The purpose of this study was to investigate the cost-effectiveness of DM implants compared with conventional bearings for primary total hip arthroplasty. Markov model analysis was conducted from the societal perspective with use of direct and indirect costs. Costs, expressed in 2013 U.S. dollars, were derived from the literature, the National Inpatient Sample, and the Centers for Medicare & Medicaid Services. Effectiveness was expressed in quality-adjusted life years (QALYs). The model was populated with health state utilities and state transition probabilities derived from previously published literature. The analysis was performed for a patient's lifetime, and costs and effectiveness were discounted at 3% annually. The principal outcome was the incremental cost-effectiveness ratio (ICER), with a willingness-to-pay threshold of $100,000/QALY. Sensitivity analyses were performed to explore relevant uncertainty. In the base case, DM total hip arthroplasty showed absolute dominance over conventional total hip arthroplasty, with lower accrued costs ($39,008 versus $40,031 U.S. dollars) and higher accrued utility (13.18 versus 13.13 QALYs) indicating cost-savings. DM total hip arthroplasty ceased being cost-saving when its implant costs exceeded those of conventional total hip arthroplasty by $1,023, and the cost-effectiveness threshold for DM implants was $5,287 greater than that for conventional implants. DM was not cost-effective when the annualized incremental probability of revision from any unforeseen failure mechanism or mechanisms exceeded 0.29%. The probability of intraprosthetic dislocation exerted the most influence on model results. This model

Dissociation of modular total hip arthroplasty at the neck-stem interface without dislocation.

PubMed

Kouzelis, A; Georgiou, C S; Megas, P

2012-12-01

Modular femoral and acetabular components are now widely used, but only a few complications related to the modularity itself have been reported. We describe a case of dissociation of the modular total hip arthroplasty (THA) at the femoral neck-stem interface during walking. The possible causes of this dissociation are discussed. Successful treatment was provided with surgical revision and replacement of the modular neck components. Surgeons who use modular components in hip arthroplasties should be aware of possible early complications in which the modularity of the prostheses is the major factor of failure.

Ankylosing Spondylitis Increases Perioperative and Postoperative Complications After Total Hip Arthroplasty.

PubMed

Blizzard, Daniel J; Penrose, Colin T; Sheets, Charles Z; Seyler, Thorsten M; Bolognesi, Michael P; Brown, Christopher R

2017-08-01

Ankylosing spondylitis (AS) is a chronic autoimmune spondyloarthropathy that primarily affects the axial spine and hips. Progressive disease leads to pronounced spinal kyphosis, positive sagittal balance, and altered biomechanics. The purpose of this study is to determine the complication profile of patients with AS undergoing total hip arthroplasty (THA). The Medicare sample was searched from 2005 to 2012 yielding 1006 patients with AS who subsequently underwent THA. Risk ratios (RRs) with 95% confidence intervals (CIs) were calculated for 90-day, 2-year, and the final postoperative follow-up for complications including hip dislocation, periprosthetic fracture, wound complication, revision THA, and postoperative infection. Compared to controls, AS patients had an RR of 2.50 (CI, 1.04-5.99) of THA component breakage at 90-days post-operatively and 1.99 (CI, 1.10-3.59) at 2-years. The RR of periprosthetic hip dislocation was elevated at 90 days (1.44; CI, 0.93-2.22) and significantly increased at 2-years (1.67; CI, 1.25-2.23) and overall follow-up (1.49; CI, 1.14-1.93). Similarly, the RR for THA revision was elevated at 90-days (1.46; CI, 0.97-2.18) and significantly increased at 2-years (1.69; CI, 1.33-2.14) and overall follow-up (1.51; CI, 1.23-1.85). Patients with AS are at increased risk for complications after THA. Altered biomechanics from a rigid, kyphotic spine place increased demand on the hip joints. The elevated perioperative and postoperative risks should be discussed preoperatively, and these patients may require increased preoperative medical optimization as well as possible changes in component selection and position to compensate for altered spinopelvic biomechanics. Copyright © 2017 Elsevier Inc. All rights reserved.

Five to thirteen year results of a cemented dual mobility socket to treat recurrent dislocation.

PubMed

Hamadouche, Moussa; Ropars, Mickael; Rodaix, Camille; Musset, Thierry; Gaucher, François; Biau, David; Courpied, Jean Pierre; Huten, Denis

2017-03-01

Dual mobility (DM) socket has been associated with a low rate of dislocation following both primary and revision total hip arthroplasty (THA). However, little is known about the long-term efficiency of DM in the treatment of THA instability. The purpose of this retrospective study was to evaluate the outcome of a cemented DM socket to treat recurrent dislocation after a minimum of five year follow-up. The series included 51 patients with a mean age of 71.3 ± 11.5 (range, 41-98) years presenting with recurrent dislocation (mean 3.3). A single DM socket design was used consisting of a stainless steel outer shell with grooves with a highly polished inner surface articulating with a mobile polyethylene component. The femoral head was captured in the polyethylene component using a snap-fit type mechanism, the latter acting as a large unconstrained head inside the metal cup. At the minimum five year follow-up evaluation, 18 of the 51 patients deceased at a mean of 4.8 ± 2.3 years, three were lost to follow-up at a mean of 1.4 years, seven had been revised at a mean of 4.7 ± 3.1 years (range, 1.5-9.1), and the remaining 23 were still alive and did not have revision at a mean of 8.2 ± 2.4 years (range, 5-13 years). Of the seven revision, three were performed for further episodes of dislocation (at the large bearing for one patient and intra-prosthetic for two patients) after a mean 5.9 ± 2.9 years (range, 2.7-9.1), whereas two were performed for late sepsis and two for aseptic loosening of the acetabular component. Radiographic analysis did not reveal any further loosening on the acetabular side. The survival rate of the cup at ten years, using re-dislocation as the end-point, was 86.1 ± 8.4% (95% confidence interval, 69.7-100%). The survival rate of the cup at ten years, using revision for any reason as the end-point, was 75.2 ± 9.3% (95% confidence interval, 56.9-93.5%). A cemented dual mobility cup was able to restore hip

High-Riding Congenital Hip Dislocation: THA With Unilateral vs Bilateral Transverse Femoral Shortening Osteotomy.

PubMed

Can, Ata; Sarikaya, Ilker A; Yontar, Necip S; Erdogan, Ayse O; Gorgun, Baris; Erdogan, Fahri

2018-05-01

We argue that 1-stage bilaterally total hip arthroplasty (THA) could be acceptable in bilateral coxarthrosis because of high-riding developmental dysplasia of the hip (DDH). Sixty-nine cases (51 patients) of high-riding DDH in patients who underwent THA from 2010 to 2013 were reviewed. Patients were divided into 2 groups: unilateral (group 1) and 1-stage bilateral surgery (group 2). The clinical measurements were the visual analog scale and Harris Hip Score. The average follow-up was 37.3 months for group 1 and 38.8 months for group 2. The hospital stay time was 5.2 days in group 1 and 6.2 days in group 2 (P = .334). The mean Harris Hip Score and visual analog scale score were improved significantly after surgery for both groups, and there was no statistically significant difference (P = .988). There was no difference between groups 1 and 2 in terms of complications (P = .137). Our data confirm that 1-stage bilateral transverse osteotomy with THA is an effective method as unilateral and it does not increase the length of patients' hospital stays and features a low risk of postoperative complications in the treatment of patients with high-riding DDH. Copyright © 2017 Elsevier Inc. All rights reserved.

Unplanned hip arthroplasty imposes clinical and cost burdens on treating institutions.

PubMed

Kamath, Atul F; Austin, Daniel C; Derman, Peter B; Israelite, Craig L

2013-12-01

Emergent surgery has been shown to be a risk factor for perioperative complications. Studies suggest that patient morbidity is greater with an unplanned hip arthroplasty, although it is controversial whether unplanned procedures also result in higher patient mortality. The financial impact of these procedures is not fully understood, as the costs of unplanned primary hip arthroplasties have not been studied previously. We asked: (1) What are the institutional costs associated with unplanned hip arthroplasties (primary THA, hemiarthroplasty, revision arthroplasty, including treatment of periprosthetic fractures, dislocations, and infections)? (2) Does timing of surgery (urgent/unplanned versus elective) influence perioperative outcomes such as mortality, length of stay, or need for advanced care? (3) What diagnoses are associated with unplanned surgery and are treated urgently most often? (4) Do demographics and insurance status differ between admission types (unplanned versus elective hip arthroplasty)? We prospectively followed all 419 patients who were admitted to our Level I trauma center in 2011 for procedures including primary THA, hemiarthroplasty, and revision arthroplasty, including the treatment of periprosthetic fractures, dislocations, and infections. Fifty-seven patients who were treated urgently on an unplanned basis were compared with 362 patients who were treated electively. Demographics, admission diagnoses, complications, and costs were recorded and analyzed statistically. Median total costs were 24% greater for patients admitted for unplanned hip arthroplasties (USD 18,206 [USD 15,261-27,491] versus USD 14,644 [USD 13,511-16,309]; p < 0.0001) for patients admitted for elective arthroplasties. Patients with unplanned admissions had a 67% longer median hospital stay (5 days [range, 4-9 days] versus 3 days [range, 3-4 days]; p < 0.0001) for patients with elective admissions. Mortality rates were equivalent between groups (p = 1.0). Femoral fracture

TEM study on relationship between stacking faults and non-basal dislocations in Mg

NASA Astrophysics Data System (ADS)

Zhang, Dalong; Jiang, Lin; Schoenung, Julie M.; Mahajan, Subhash; Lavernia, Enrique J.

2015-12-01

Recent interest in the study of stacking faults and non-basal slip in Mg alloys is partly based on the argument that these phenomena positively influence mechanical behaviour. Inspection of the published literature, however, reveals that there is a lack of fundamental information on the mechanisms that govern the formation of stacking faults, especially I1-type stacking faults (I1 faults). Moreover, controversial and sometimes contradictory mechanisms have been proposed concerning the interactions between stacking faults and dislocations. Therefore, we describe a fundamental transmission electron microscope investigation on Mg 2.5 at. % Y (Mg-2.5Y) processed via hot isostatic pressing (HIP) and extrusion at 623 K. In the as-HIPed Mg-2.5Y, many and dislocations, together with some dislocations were documented, but no stacking faults were observed. In contrast, in the as-extruded Mg-2.5Y, a relatively high density of stacking faults and some non-basal dislocations were documented. Specifically, there were three different cases for the configurations of observed stacking faults. Case (I): pure I2 faults; Case (II): mixture of I1 faults and non-basal dislocations having component, together with basal dislocations; Case (III): mixture of predominant I2 faults and rare I1 faults, together with jog-like dislocation configuration. By comparing the differences in extended defect configurations, we propose three distinct stacking fault formation mechanisms for each case in the context of slip activity and point defect generation during extrusion. Furthermore, we discuss the role of stacking faults on deformation mechanisms in the context of dynamic interactions between stacking faults and non-basal slip.

[Results and experiences of conversion of hip arthrodesis ].

PubMed

Schuh, A; Zeiler, G; Werber, S

2005-03-01

With the predictably good outcome of total hip arthroplasty today (THA), hip arthrodesis currently has limited indications. Over the long term, however, most patients develop secondary degenerative arthritis in the spine, contralateral hip, and ipsilateral knee due to overloading. The deteriorating condition of these joints eventually causes the onset of pain, which often requires conversion of a fused hip to a THA. The results and experiences of conversions of a hip arthrodesis into a THA are reported. Between 1 January 1985 and 31 December 2001 conversion of a previously performed arthrodesis of the hip to THA was carried out in a total of 45 patients; 34 patients could be followed up after the conversion to THA after a mean of 77.5 months (min.: 24, max.: 208). The primary indications for the conversion were low back pain (n=21) and ipsilateral knee pain (n=13). The mean age at the time of THA was 75.3 years (min.: 32, max.: 74). The mean time interval between the arthrodesis and the conversion to THA was 30.4 years (min.: 5, max.: 66). Of 34 hips, 29 (85%) were either pain free or had minimal pain. Complications included one persisting sciatic nerve palsy, two superficial infections, two periprosthetic fractures, and two heterotopic ossifications IV degrees with one recurrence of ankylosis and one marked reduction of motion. Revision arthroplasty was performed in four hips. Postoperatively 7 patients showed no limping, 11 showed a slight limp, and 17 a pronounced limp. Recurrent dislocations occurred in one patient. We conclude that this operation can lead to satisfactory results even after a long duration of the arthrodesis. There is a high rate of complications after conversion of a hip arthrodesis to a total hip arthroplasty. These issues must be carefully considered and discussed with the patient before any conversion procedure.

Anterior total hip arthroplasty using a metaphyseal bone-sparing stem: component alignment and early complications.

PubMed

Ahmed, Mohammed M; Otto, Thomas J; Moed, Berton R

2016-04-22

Limited-incision total hip arthroplasty (THA) preserves hip abductors, posterior capsule, and external rotators potentially diminishing dislocation risk. However, potential complications also exist, such as component malposition. Specific implants have been manufactured that enhance compatibility with this technique, while preserving metaphyseal bone; however, little data exists documenting early complications and component position. The purpose was to evaluate primary THA using a curved, bone-sparing stem inserted through the anterior approach with respect to component alignment and early complications. In a retrospective analysis of 108 cases, the surgical technique was outlined and the occurrence of intraoperative fractures, postoperative dislocations, infection, and limb length inequality was determined. Femoral stem and acetabular cup alignment was quantified using the initial postoperative radiographs. Patient follow-up averaged 12.9 (range 2 to 36) months. There were eight (7.4 %) complications requiring revision surgery in three (2.8 %) patients with three (2.8 %) infections and three (2.8 %) dislocations. Intraoperative complications included one calcar fracture above the lesser trochanter. Leg length inequality >5 mm was present in three (2.8 %) patients. Radiographic analysis showed that femoral neutral alignment was achieved in 95 hips (88.0 %). All femoral stems demonstrated satisfactory fit and fill and no evidence of subsidence, osteolysis, or loosening. An average abduction angle of 44.8° (± 5.3) and average cup anteversion of 16.2° (± 4.2) were also noted. Although the technique with this implant and approach is promising, it does not appear to offer important advantages over standard techniques. However, the findings merit further, long-term study.

Bearing Change to Metal-On-Polyethylene for Ceramic Bearing Fracture in Total Hip Arthroplasty; Does It Work?

PubMed

Lee, Soong Joon; Kwak, Hong Suk; Yoo, Jeong Joon; Kim, Hee Joong

2016-01-01

We evaluated the short-term to midterm results of reoperation with bearing change to metal-on-polyethylene (MoP) after ceramic bearing fracture in ceramic-on-ceramic total hip arthroplasty. Nine third-generation ceramic bearing fractures (6 heads and 3 liners) were treated with bearing change to MoP. Mean age at reoperation was 52.7 years. Mean follow-up was 4.3 years. During follow-up, 2 of 3 liner-fractured hips and 1 of 6 head-fractured hips showed radiologic signs of metallosis and elevated serum chromium levels. Re-reoperation with bearing rechange to a ceramic head was performed for the hips with metallosis. One liner-fractured hip had periprosthetic joint infection. Dislocation occurred in 3 hips. From our experience, bearing change to MoP is not a recommended treatment option for ceramic bearing fracture in total hip arthroplasty. Copyright © 2016 Elsevier Inc. All rights reserved.

Dislocation

MedlinePlus

... Dislocations can occur in contact sports, such as football and hockey, and in sports in which falls ... downhill skiing, gymnastics and volleyball. Basketball players and football players also commonly dislocate joints in their fingers ...

Sexual activity after total hip replacement in Korean patients: how they do, what they want, and how to improve.

PubMed

Yoon, Byung-Ho; Lee, Kyung-Hag; Noh, Serae; Ha, Yong-Chan; Lee, Young-Kyun; Koo, Kyung-Hoi

2013-12-01

Concerns of patients on sexual activity after total hip arthroplasty have not been well studied in Asian patients. This study aimed to determine the following: (1) what are the concerns of patients related to sexual activity after total hip arthroplasty? (2) what are the changes in sexual activity after total hip replacement in Korean patients? Details of sexual activity and concerns were obtained using a questionnaire designed specifically for the study. The questionnaire was administered to 64 patients in a face-to-face interview at an outpatient clinic. Preoperatively, 53.1% of patients experienced difficulties, primarily due to hip pathology and limitations of motion. The median time to the resumption of sexual activity was 3 months postoperatively, and most patients had no increase in the frequency of sexual activity after the total hip replacement. In 39.1% of patients were seen having difficulties with leg positioning following total hip replacement, and they were likely to change coital positions. The most common concern regarding sexual activity of patients was the fear of dislocation. Furthermore, patients with a higher stress level had lower satisfaction rates. Most patients were unable to obtain information on sexual activity following the total hip arthroplasty, and they did not consult with a physician due to the private nature of the topic. Dislocation was the most common concern of patients during sexual activity following a total hip arthroplasty, and a higher stress level was found to be associated with a lower satisfaction rate. Because most patients were unprepared to consult a physician, the provision of appropriate information before a consultation might be beneficial.

Sexual Activity after Total Hip Replacement in Korean Patients: How They Do, What They Want, and How to Improve

PubMed Central

Yoon, Byung-Ho; Lee, Kyung-Hag; Noh, Serae; Ha, Yong-Chan; Koo, Kyung-Hoi

2013-01-01

Background Concerns of patients on sexual activity after total hip arthroplasty have not been well studied in Asian patients. This study aimed to determine the following: (1) what are the concerns of patients related to sexual activity after total hip arthroplasty? (2) what are the changes in sexual activity after total hip replacement in Korean patients? Methods Details of sexual activity and concerns were obtained using a questionnaire designed specifically for the study. The questionnaire was administered to 64 patients in a face-to-face interview at an outpatient clinic. Results Preoperatively, 53.1% of patients experienced difficulties, primarily due to hip pathology and limitations of motion. The median time to the resumption of sexual activity was 3 months postoperatively, and most patients had no increase in the frequency of sexual activity after the total hip replacement. In 39.1% of patients were seen having difficulties with leg positioning following total hip replacement, and they were likely to change coital positions. The most common concern regarding sexual activity of patients was the fear of dislocation. Furthermore, patients with a higher stress level had lower satisfaction rates. Most patients were unable to obtain information on sexual activity following the total hip arthroplasty, and they did not consult with a physician due to the private nature of the topic. Conclusions Dislocation was the most common concern of patients during sexual activity following a total hip arthroplasty, and a higher stress level was found to be associated with a lower satisfaction rate. Because most patients were unprepared to consult a physician, the provision of appropriate information before a consultation might be beneficial. PMID:24340146

Initial dislocation structure and dynamic dislocation multiplication in Mo single crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsiung, L M; Lassila, D H

Initial dislocation structure in annealed high-purity Mo single crystals and deformation substructure in a crystal subjected to 1% compression have been examined and studied in order to investigate dislocation multiplication mechanisms in the early stages of plastic deformation. The initial dislocation density is in a range of 10{sup 6} {approx} 10{sup 7} cm{sup -2}, and the dislocation structure is found to contain many grown-in superjogs along dislocation lines. The dislocation density increases to a range of 10{sup 8} {approx} 10{sup 9} cm{sup -2}, and the average jog height is also found to increase after compressing for a total strain ofmore » 1%. It is proposed that the preexisting jogged screw dislocations can act as (multiple) dislocation multiplication sources when deformed under quasi-static conditions. Both the jog height and length of link segment (between jogs) can increase by stress-induced jog coalescence, which takes place via the lateral migration (drift) of superjogs driven by unbalanced line-tension partials acting on link segments of unequal lengths. Applied shear stress begins to push each link segment to precede dislocation multiplication when link length and jog height are greater than critical lengths. This dynamic dislocation multiplication source is subsequently verified by direct simulations of dislocation dynamics under stress to be crucial in the early stages of plastic deformation in Mo single crystals.« less

Interventions for Hip Pain in the Maturing Athlete

PubMed Central

Gomberawalla, M. Mustafa; Kelly, Bryan T.; Bedi, Asheesh

2014-01-01

Context: Femoroacetabular impingement (FAI) alters hip mechanics, results in hip pain, and may lead to secondary osteoarthritis (OA) in the maturing athlete. Hip impingement can be caused by osseous abnormalities in the proximal femur or acetabulum. These impingement lesions may cause altered loads within the hip joint, which result in repetitive collision damage or sheer forces to the chondral surfaces and acetabular labrum. These anatomic lesions and resultant abnormal mechanics may lead to early osteoarthritic changes. Evidence Acquisition: Relevant articles from the years 1995 to 2013 were identified using MEDLINE, EMBASE, and the bibliographies of reviewed publications. Level of Evidence: Level 4. Results: Improvements in hip arthroscopy have allowed FAI to be addressed utilizing the arthroscope. Adequately resecting the underlying osseous abnormalities is essential to improving hip symptomatology and preventing further chondral damage. Additionally, preserving the labrum by repairing the damaged tissue and restoring the suction seal may theoretically help normalize hip mechanics and prevent further arthritic changes. The outcomes of joint-preserving treatment options may be varied in the maturing athlete due to the degree of underlying OA. Irreversible damage to the hip joint may have already occurred in patients with moderate to advanced OA. In the presence of preexisting arthritis, these patients may only experience fair or even poor results after hip arthroscopy, with early conversion to hip replacement. For patients with advanced hip arthritis, total hip arthroplasty remains a treatment option to reliably improve symptoms with good to excellent outcomes and return to low-impact activities. Conclusion: Advances in the knowledge base and treatment techniques of intra-articular hip pain have allowed surgeons to address this complex clinical problem with promising outcomes. Traditionally, open surgical dislocations for hip preservation surgery have shown good

Dislocations

MedlinePlus

... Things That Help Feelings Expert Answers Q&A Movies & More for Teens ... A dislocation is when two connected bones become separated. Dislocations are caused by falls and hard impacts, such as in sports injuries, and are more ...

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

NASA Astrophysics Data System (ADS)

Shi, X. J.; Dupuy, L.; Devincre, B.; Terentyev, D.; Vincent, L.

2015-05-01

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.

Treatment of Crowe Type-IV Hip Dysplasia Using Cementless Total Hip Arthroplasty and Double Chevron Subtrochanteric Shortening Osteotomy: A 5- to 10-Year Follow-Up Study.

PubMed

Li, Xigong; Lu, Yang; Sun, Junying; Lin, Xiangjin; Tang, Tiansi

2017-02-01

The purpose of this study was to evaluate the functional and radiographic results of patients with Crowe type-IV hip dysplasia treated by cementless total hip arthroplasty and double chevron subtrochanteric osteotomy. From January 2000 to February 2006, cementless total hip arthroplasty with a double chevron subtrochanteric shortening osteotomy was performed on 18 patients (22 hips) with Crowe type-IV dysplasia. The acetabular cup was placed in the position of the anatomic hip center, and subtrochanteric femoral shortening osteotomy was performed with the use of a double chevron design. The clinical and radiographic outcomes were reviewed with a mean follow-up of 6.5 years (5-10 years). The mean amount of femoral subtrochanteric shortening was 38 mm (25-60 mm). All osteotomy sites were healed by 3-6 months without complications. The mean Harris Hip Score improved significantly from 47 points (35-65 points) preoperatively to 88 points (75-97 points) at the final follow-up. The Trendelenburg sign was corrected from a positive preoperative status to a negative postoperative status in 12 of 22 hips. No acetabular and femoral components have loosened or required revision during the period of follow-up. Cementless total hip arthroplasty using double chevron subtrochanteric osteotomy allowed for restoration of anatomic hip center with safely functional limb lengthening, achieved correction of preoperative limp, and good functional and radiographic outcomes for 22 Crowe type-IV dislocation hips at the time of the 5- to 10-year follow-up. Copyright © 2016 Elsevier Inc. All rights reserved.

Lawsuits After Primary and Revision Total Hip Arthroplasties: A Malpractice Claims Analysis.

PubMed

Patterson, Diana C; Grelsamer, Ronald P; Bronson, Michael J; Moucha, Calin S

2017-10-01

As the prevalence of total hip arthroplasty (THA) expands, so too will complications and patient dissatisfaction. The goal of this study was to identify the common etiologies of malpractice suits and costs of claims after primary and revision THAs. Analysis of 115 malpractice claims filed for alleged neglectful primary and revision THA surgeries by orthopedic surgeons insured by a large New York state malpractice carrier between 1983 and 2011. The incidence of malpractice claims filed for negligent THA procedures is only 0.15% per year in our population. In primary cases, nerve injury ("foot drop") was the most frequent allegation with 27 claims. Negligent surgery causing dislocation was alleged in 18 and leg length discrepancy in 14. Medical complications were also reported, including 3 thromboembolic events and 6 deaths. In revision cases, dislocation and infection were the most common source of suits. The average indemnity payment was $386,153 and the largest single settlement was $4.1 million for an arterial injury resulting in amputation after a primary hip replacement. The average litigation cost to the insurer was $61,833. Nerve injury, dislocation, and leg length discrepancy are the most common reason for malpractice after primary THA. Orthopedic surgeons should continue to focus on minimizing the occurrence of these complications while adequately incorporating details about the risks and limitations of surgery into their preoperative education. Copyright © 2017 Elsevier Inc. All rights reserved.

Temporomandibular joint dislocation

PubMed Central

Sharma, Naresh Kumar; Singh, Akhilesh Kumar; Pandey, Arun; Verma, Vishal; Singh, Shreya

2015-01-01

Temporomandibular joint (TMJ) dislocation is an uncommon but debilitating condition of the facial skeleton. The condition may be acute or chronic. Acute TMJ dislocation is common in clinical practice and can be managed easily with manual reduction. Chronic recurrent TMJ dislocation is a challenging situation to manage. In this article, we discuss the comprehensive review of the different treatment modalities in managing TMJ dislocation. PMID:26668447

Short-term clinical experience with hip resurfacing arthroplasty.

PubMed

Cieliński, Łukasz; Kusz, Damian; Wojciechowski, Piotr; Dziuba, Anna

2007-01-01

This paper discusses the authors' experience with hip resurfacing arthroplasty. Although introduced many years ago, the method did not gain wide popularity because of poor long-term outcomes. At present, owing to the introduction of metal-on-metal bearings and hybrid fixation techniques, short- and mid-term results are very good and encourage wider use of this technique, especially in the younger and more active patients whose results with standard total hip replacements would be unsatisfactory. We performed 13 hip resurfacing arthroplasties at our institution between August 1, 2005, and May 1, 2006. Twelve patients reported for the scheduled follow-up and were included in the study. Treatment outcomes were assessed according to the Harris Hip Score. The short-term outcomes of hip resurfacing arthroplasties are encouraging. In the study group there were no intraoperative complications, infections, peripheral nerve palsy, hip dislocations or clinically overt vein thrombosis. All of the patients reported complete or major pain relief. Clinical assessment according to the Harris Hip Score revealed improvement from an average of 57.7 (20.1) points preoperatively to an average of 87.7 (12) points after the surgery. Crutches were used for a maximum of 6 weeks postoperatively. All of the patients are currently able to walk without crutches with full weight-bearing. 1) Hip resurfacing arthroplasty seems to be an advisable method of operative management of younger, active patients, in whom standard THR would be associated with a high risk of failure; it allows THR to be postponed and carried out as a revision surgery with the acetabular component already in place. 2) Despite the good short- and mid-term results, the utility of this method should be evaluated with caution due to the lack of adequate long-term follow-up data.

Internet search term affects the quality and accuracy of online information about developmental hip dysplasia.

PubMed

Fabricant, Peter D; Dy, Christopher J; Patel, Ronak M; Blanco, John S; Doyle, Shevaun M

2013-06-01

The recent emphasis on shared decision-making has increased the role of the Internet as a readily accessible medical reference source for patients and families. However, the lack of professional review creates concern over the quality, accuracy, and readability of medical information available to patients on the Internet. Three Internet search engines (Google, Yahoo, and Bing) were evaluated prospectively using 3 difference search terms of varying sophistication ("congenital hip dislocation," "developmental dysplasia of the hip," and "hip dysplasia in children"). Sixty-three unique Web sites were evaluated by each of 3 surgeons (2 fellowship-trained pediatric orthopaedic attendings and 1 orthopaedic chief resident) for quality and accuracy using a set of scoring criteria based on the AAOS/POSNA patient education Web site. The readability (literacy grade level) of each Web site was assessed using the Fleisch-Kincaid score. There were significant differences noted in quality, accuracy, and readability of information depending on the search term used. The search term "developmental dysplasia of the hip" provided higher quality and accuracy compared with the search term "congenital hip dislocation." Of the 63 total Web sites, 1 (1.6%) was below the sixth grade reading level recommended by the NIH for health education materials and 8 (12.7%) Web sites were below the average American reading level (eighth grade). The quality and accuracy of information available on the Internet regarding developmental hip dysplasia significantly varied with the search term used. Patients seeking information about DDH on the Internet may not understand the materials found because nearly all of the Web sites are written at a level above that recommended for publically distributed health information. Physicians should advise their patients to search for information using the term "developmental dysplasia of the hip" or, better yet, should refer patients to Web sites that they have

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

NASA Astrophysics Data System (ADS)

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.

Congenital joint dislocations caused by carbohydrate sulfotransferase 3 deficiency in recessive Larsen syndrome and humero-spinal dysostosis.

PubMed

Hermanns, Pia; Unger, Sheila; Rossi, Antonio; Perez-Aytes, Antonio; Cortina, Hector; Bonafé, Luisa; Boccone, Loredana; Setzu, Valeria; Dutoit, Michel; Sangiorgi, Luca; Pecora, Fabio; Reicherter, Kerstin; Nishimura, Gen; Spranger, Jürgen; Zabel, Bernhard; Superti-Furga, Andrea

2008-06-01

Deficiency of carbohydrate sulfotransferase 3 (CHST3; also known as chondroitin-6-sulfotransferase) has been reported in a single kindred so far and in association with a phenotype of severe chondrodysplasia with progressive spinal involvement. We report eight CHST3 mutations in six unrelated individuals who presented at birth with congenital joint dislocations. These patients had been given a diagnosis of either Larsen syndrome (three individuals) or humero-spinal dysostosis (three individuals), and their clinical features included congenital dislocation of the knees, elbow joint dysplasia with subluxation and limited extension, hip dysplasia or dislocation, clubfoot, short stature, and kyphoscoliosis developing in late childhood. Analysis of chondroitin sulfate proteoglycans in dermal fibroblasts showed markedly decreased 6-O-sulfation but enhanced 4-O-sulfation, confirming functional impairment of CHST3 and distinguishing them from diastrophic dysplasia sulphate transporter (DTDST)-deficient cells. These observations provide a molecular basis for recessive Larsen syndrome and indicate that recessive Larsen syndrome, humero-spinal dysostosis, and spondyloepiphyseal dysplasia Omani type form a phenotypic spectrum.

Primary total hip arthroplasty versus hemiarthroplasty for displaced intracapsular hip fractures in older patients: systematic review.

PubMed

Hopley, Colin; Stengel, Dirk; Ekkernkamp, Axel; Wich, Michael

2010-06-11

hip arthroplasty over hemiarthroplasty. Total hip arthroplasty was associated with a slightly higher risk of dislocation (relative risk 1.48, 95% confidence interval 0.89 to 2.46) and general complications (1.14, 0.87 to 1.48). Single stage total hip arthroplasty may lead to lower reoperation rates and better functional outcomes compared with hemiarthroplasty in older patients with displaced femoral neck fractures. However, heterogeneity across the available trials and distinct subgroup effects preclude definitive statements and require further research in this area.

Hip health at skeletal maturity: a population-based study of young adults with cerebral palsy.

PubMed

Wawrzuta, Joanna; Willoughby, Kate L; Molesworth, Charlotte; Ang, Soon Ghee; Shore, Benjamin J; Thomason, Pam; Graham, H Kerr

2016-12-01

We studied 'hip health' in a population-based cohort of adolescents and young adults with cerebral palsy to investigate associations between hip morphology, pain, and gross motor function. Ninety-eight young adults (65 males, 33 females) from the birth cohort were identified as having developed hip displacement (migration percentage >30) and were reviewed at a mean age of 18 years 10 months (range 15-24y). Hip morphology was classified using the Melbourne Cerebral Palsy Hip Classification Scale (MCPHCS). Severity and frequency of pain were recorded using Likert scales. Gross motor function was classified by the Gross Motor Function Classification System (GMFCS). Hip pain was reported in 72% of participants. Associations were found between pain scores and both hip morphology and GMFCS. Median pain severity score for MCPHCS grades 1 to 4 was 2 (interquartile range [IQR] 1.0-3.0) compared to 7 (IQR 6.0-8.0) for grades 5 and 6 (severe subluxation or dislocation). Hip surveillance and access to surgery were associated with improved hip morphology and less pain. Poor hip morphology at skeletal maturity was associated with high levels of pain. Limited hip surveillance and access to surgery, rather than GMFCS, was associated with poor hip morphology. The majority of young adults who had access to hip surveillance, and preventive and reconstructive surgery, had satisfactory hip morphology at skeletal maturity and less pain. © 2016 Mac Keith Press.

Multiscale modeling of dislocation-precipitate interactions in Fe: From molecular dynamics to discrete dislocations.

PubMed

Lehtinen, Arttu; Granberg, Fredric; Laurson, Lasse; Nordlund, Kai; Alava, Mikko J

2016-01-01

The stress-driven motion of dislocations in crystalline solids, and thus the ensuing plastic deformation process, is greatly influenced by the presence or absence of various pointlike defects such as precipitates or solute atoms. These defects act as obstacles for dislocation motion and hence affect the mechanical properties of the material. Here we combine molecular dynamics studies with three-dimensional discrete dislocation dynamics simulations in order to model the interaction between different kinds of precipitates and a 1/2〈111〉{110} edge dislocation in BCC iron. We have implemented immobile spherical precipitates into the ParaDis discrete dislocation dynamics code, with the dislocations interacting with the precipitates via a Gaussian potential, generating a normal force acting on the dislocation segments. The parameters used in the discrete dislocation dynamics simulations for the precipitate potential, the dislocation mobility, shear modulus, and dislocation core energy are obtained from molecular dynamics simulations. We compare the critical stresses needed to unpin the dislocation from the precipitate in molecular dynamics and discrete dislocation dynamics simulations in order to fit the two methods together and discuss the variety of the relevant pinning and depinning mechanisms.

Prospective monitoring improves outcomes of primary total hip replacement: a cohort study

PubMed Central

Streubel, Philipp N; Pachón, Marcela; Kerguelén, Carlos A; Navas, José; Portocarrero, Julio; Pesantez, Rodrigo F; Zayed, Gamal; Carrillo, Germán; Llinás, Adolfo M

2009-01-01

Background Over the past decade several studies have questioned current standards of patient safety in health care delivery. In response, our institution started a clinical pathway for total hip replacement in 1996. Prospective monitoring with regular feedback sessions to the individuals involved in patient care did however not start until 2003. The present study evaluates the effect of prospective monitoring on outcomes of total hip replacement. Methods Clinical records of patients undergoing primary elective total hip replacement between 1997 and 2004 were reviewed. Data on adverse events as well as adherence to protocols for venous thromboembolism prophylaxis were extracted retrospectively for the period 1997 to 2001 and prospectively from 2003 to 2004. Results were compared and analyzed in order to establish possible improvement in outcomes. Data was analyzed with Chi-square or Fisher's Exact test for categorical variables and Student's t-test for continuous variables. Alpha was set as less than 5% and analysis was performed with Stata 9.0 for Macintosh. Results Two-hundred and eighty-three patients were included from 1997 to 2001, and 62 from 2003 to 2004. Mean age, male to female ratio and initial diagnosis were similar in both groups. At least one adverse event occurred in 45% of patients in 1997–2001 and in 21% in 2003–2004 (p < 0.001). In-hospital hip dislocations occurred in 6% and 0% (p = 0.05), oliguria in 19% and 5% (p = 0.007), SSI and VTE in 3% and 0% (p = 0.37), adverse drug reactions in 11% and 13% (p = 0.66) and non-adherence to VTE prophylaxis protocols in 15% and 2% of cases respectively (p = 0.002). Conclusion Overall rate of adverse events as well as in-hospital hip dislocations, oliguria and non-adherence to VTE prophylaxis protocols were significantly reduced during the second period. We conclude that clinical pathways alone are insufficient to improve patient safety and require prospective monitoring and continuous feedback to health

[Application of computer-aided osteotomy template design in treatment of developmental dysplasia of the hip with steel osteotomy].

PubMed

Tong, Kuang; Zhang, Yuanzhi; Zhang, Sheng; Yu, Bin

2013-06-01

To provide an accurate method for osteotomy in the treatment of developmental dysplasia of the hip with steel osteotomy by three-dimensional reconstruction and Reverse Engineering technique. Between January 2011 and December 2012, 13 children with developmental dysplasia of the hip underwent steel osteotomy. 3D CT scan pelvic images were obtained and transferred via a DICOM network into a computer workstation to construct 3D models of the hip using Materialise Mimics 14.1 software in STL format. These models were imported into Imageware 12.0 software for steel osteotomy simulation until a stable hip was attained in the anatomical position for dislocation or subluxation of the hip in older children. The osteotomy navigational templates were designed according to the anatomical features after a stable hip was reconstructed. These navigational templates were manufactured using a rapid prototyping technique. The reconstruction hips in these children show good matching property and acetabulum cover. The computer-aided design of osteotomy template provides personalized and accurate solutions in the treatment of developmental dysplasia of the hip with steel osteotomy in older children.

Hip pathology in Majewski osteodysplastic primordial dwarfism type II.

PubMed

Karatas, Ali F; Bober, Michael B; Rogers, Kenneth; Duker, Angela L; Ditro, Colleen P; Mackenzie, William G

2014-09-01

Majewski osteodysplastic primordial dwarfism type II (MOPDII) is characterized by severe prenatal and postnatal growth failure with microcephaly, characteristic skeletal dysplasia, an increased risk for cerebrovascular disease, and insulin resistance. MOPDII is caused by mutations in the pericentrin (PCNT) gene and is inherited in an autosomal-recessive manner. This study aimed to determine the incidence of hip pathology in patients with molecularly confirmed MOPDII and to describe the functional outcomes of surgical treatment. Thirty-three enrolled patients had a clinical diagnosis of MOPDII. Biallelic PCNT mutations or absent pericentrin protein was confirmed in 25 of these patients. Twelve patients (7 female) had appropriate clinical and radiographic records at this institution and were included in this study. The data collected included age at presentation, age at surgery, sex, body weight and height, weight-bearing status at diagnosis, and the clinical examination. Four patients (31%) had coxa vara: 3 unilateral and 1 bilateral. Three unilateral patients had in situ pinning at a mean age 4 years. The patient with bilateral coxa vara had valgus osteotomy at the age of 5 years. Two children had bilateral hip dysplasia and subluxation with no surgery. One patient had bilateral developmental hip dislocations. The patient was treated by open reduction-spica cast and 2 years after surgery, coxa valga was noted. Another patient was diagnosed at an age of 12 years with bilateral avascular necrosis of the hips. Four patients did not have hip pathology. Hip pathology is common among children with MOPDII; coxa vara is the most frequent diagnosis. Routine clinical and radiographic hip evaluation is important. The capital femoral epiphysis appears to slip down along the shaft, giving the appearance of a proximal femoral epiphysiolysis. A hip diagnosed with slipped capital femoral epiphysis in early life may progress to severe coxa vara. Level IV.

[A therapeutic effect analysis of femur first principle and combined anteversion technique during total hip arthroplasty].

PubMed

Wang, X Q; Wu, C S; Sun, S; Wang, J; Li, W; Zhang, W

2018-04-01

Objective: To investigate the situation of hip dislocation with the application of "femur first" principle and "combined anteversion technique" during total hip arthroplasty. Methods: A retrospective analysis has been done on the clinical data about 104 patients(133 hips)who were diagnosed as hip disease and were treated with total hip arthroplasty by the doctors from the Department of Joint Orthorpaedics of Shandong Provincial Hospital Affiliated to Shandong University from June 2014 to June 2016, and all the prostheses applied in the operation were cementless ones.Among them, 65 patients were males, 39 females and their age was 46.6 years (ranging from 23 to 76 years) .And 29 of them underwent bilateral hip operations and 75 unilateral ones.Seventy-six cases of aseptic necrosis of the femoral head in the terminal stage, 28 cases of hip dysplasia and osteoarthritis.Surgical approach: of all the operations, 103 hips were operated on with hardinge approach, 30 with posterolateral approach.During the operation, first of all, the femoral medullary cavity was broached and then the anteversion of intramedullary broacher was measured.After that, the anteversion of the acetabular cup was calculated as 37° minus the anteversion of the broacher, and the acetabular cup was implanted at that angle.The patients' prosthesis combined anteversion, range of motion of the hip joint, operation time, hemorrhage amount, and complications had been kept record.One, three, and six months respectively after the operation, all the patients received outpatient review, and took anteroposterior and lateral position X-ray examination.Harris hip score had been applied to evaluate their hip function before the operation and six months after the operation. Results: All the patients had been operated on smoothly, with the operation time of(57.6±14.5)minutes(36-115 minutes)and hemorrhage amount of (336.5±50.8)ml(180-620 ml). The operation finding showed that the combined anteversion by employing

Hip resurfacing: a large, US single-surgeon series.

PubMed

Brooks, P J

2016-01-01

Hip resurfacing has been proposed as an alternative to traditional total hip arthroplasty in young, active patients. Much has been learned following the introduction of metal-on-metal resurfacing devices in the 1990s. The triad of a well-designed device, implanted accurately, in the correct patient has never been more critical than with these implants. Following Food and Drug Administration approval in 2006, we studied the safety and effectiveness of one hip resurfacing device (Birmingham Hip Resurfacing) at our hospital in a large, single-surgeon series. We report our early to mid-term results in 1333 cases followed for a mean of 4.3 years (2 to 5.7) using a prospective, observational registry. The mean patient age was 53.1 years (12 to 84); 70% were male and 91% had osteoarthritis. Complications were few, including no dislocations, no femoral component loosening, two femoral neck fractures (0.15%), one socket loosening (0.08%), three deep infections (0.23%), and three cases of metallosis (0.23%). There were no destructive pseudotumours. Overall survivorship at up to 5.7 years was 99.2%. Aseptic survivorship in males under the age of 50 was 100%. We believe this is the largest United States series of a single surgeon using a single resurfacing system. ©2016 The British Editorial Society of Bone & Joint Surgery.

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

NASA Astrophysics Data System (ADS)

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.

Glide dislocation nucleation from dislocation nodes at semi-coherent {111} Cu–Ni interfaces

DOE PAGES

Shao, Shuai; Wang, Jian; Beyerlein, Irene J.; ...

2015-07-23

Using atomistic simulations and dislocation theory on a model system of semi-coherent {1 1 1} interfaces, we show that misfit dislocation nodes adopt multiple atomic arrangements corresponding to the creation and redistribution of excess volume at the nodes. We identified four distinctive node structures: volume-smeared nodes with (i) spiral or (ii) straight dislocation patterns, and volume-condensed nodes with (iii) triangular or (iv) hexagonal dislocation patterns. Volume-smeared nodes contain interfacial dislocations lying in the Cu–Ni interface but volume-condensed nodes contain two sets of interfacial dislocations in the two adjacent interfaces and jogs across the atomic layer between the two adjacent interfaces.more » Finally, under biaxial tension/compression applied parallel to the interface, we show that the nucleation of lattice dislocations is preferred at the nodes and is correlated with the reduction of excess volume at the nodes.« less

A financial analysis of revision hip arthroplasty: the economic burden in relation to the national tariff.

PubMed

Vanhegan, I S; Malik, A K; Jayakumar, P; Ul Islam, S; Haddad, F S

2012-05-01

Revision arthroplasty of the hip is expensive owing to the increased cost of pre-operative investigations, surgical implants and instrumentation, protracted hospital stay and drugs. We compared the costs of performing this surgery for aseptic loosening, dislocation, deep infection and peri-prosthetic fracture. Clinical, demographic and economic data were obtained for 305 consecutive revision total hip replacements in 286 patients performed at a tertiary referral centre between 1999 and 2008. The mean total costs for revision surgery in aseptic cases (n = 194) were £11 897 (sd 4629), for septic revision (n = 76) £21 937 (sd 10 965), for peri-prosthetic fracture (n = 24) £18 185 (sd 9124), and for dislocation (n = 11) £10 893 (sd 5476). Surgery for deep infection and peri-prosthetic fracture was associated with longer operating times, increased blood loss and an increase in complications compared to revisions for aseptic loosening. Total inpatient stay was also significantly longer on average (p < 0.001). Financial costs vary significantly by indication, which is not reflected in current National Health Service tariffs.

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

PubMed

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.

Debye screening of dislocations.

PubMed

Groma, I; Györgyi, G; Kocsis, B

2006-04-28

Debye-like screening by edge dislocations of some externally given stress is studied by means of a variational approach to coarse grained field theory. Explicitly given are the force field and the induced geometrically necessary dislocation (GND) distribution, in the special case of a single glide axis in 2D, for (i) a single edge dislocation and (ii) a dislocation wall. Numerical simulation demonstrates that the correlation in relaxed dislocation configurations is in good agreement with the induced GND in case (i). Furthermore, the result (ii) well predicts the experimentally observed decay length for the GND developing close to grain boundaries.

Early experience with dual mobility acetabular systems featuring highly cross-linked polyethylene liners for primary hip arthroplasty in patients under fifty five years of age: an international multi-centre preliminary study.

PubMed

Epinette, Jean-Alain; Harwin, Steven F; Rowan, Fiachra E; Tracol, Philippe; Mont, Michael A; Chughtai, Morad; Westrich, Geoffrey H

2017-03-01

To evaluate early performance of contemporary dual mobility acetabular systems with second generation annealed highly cross-linked polyethylene for primary hip arthroplasty of patients under 55 years of age. A prospective observational five years study across five centers in Europe and the USA of 321 patients with a mean age of 48.1 years was performed. Patients were assessed for causes of revision, hip instability, intra-prosthetic dissociation, Harris hip score and radiological signs of osteolysis. There were no dislocations and no intra-prosthetic dissociations. Kaplan Meier analysis demonstrated 97.51% survivorship for all cause revision and 99.68% survivorship for acetabular component revision at five years. Mean Harris hip score was 93.6. Two acetabular shells were revised for neck-rim implant impingement without dislocation and ten femoral stems were revised for causes unrelated to dual mobility implants. Contemporary highly cross-linked polyethylene dual mobility systems demonstrate excellent early clinical, radiological, and survivorship results in a cohort of patients that demand high performance from their implants. It is envisaged that DM and second generation annealed HXLPE may reduce THA instability and wear, the two most common causes of THA revision in hip arthroplasty.

Tailoring Superconductivity with Quantum Dislocations.

PubMed

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.

Adverse Outcomes in Infantile Bilateral Developmental Dysplasia of the Hip.

PubMed

Morbi, Abigail H M; Carsi, Belen; Gorianinov, Vitalli; Clarke, Nicholas M P

2015-01-01

It is believed that bilateral developmental dysplasia of the hip (DDH) has poorer outcomes with higher rates of avascular necrosis (AVN) and reintervention, compared with unilateral DDH. However, there is limited evidence in the literature, with few studies looking specifically at bilateral cases. A retrospective review of 36 patients (72 hips) with >4 years of follow-up. Patient population included surgically treated DDH including late presentations and failures of conservative treatment. The dislocated hips underwent either simultaneous closed or 1 open and 1 closed, or sequential open reduction. AVN and secondary procedures were used as endpoints for analysis as well as clinical and radiologic outcomes. At the last follow-up, 33% of hips had radiologic signs of AVN. Those hips that had no ossific nucleus (ON) at the time of surgery had an odds ratio of developing AVN of 3.05 and a statistically significant association between the 2 variables, whereas open/closed or simultaneous/sequential reduction did not increase the risk for AVN. In addition, 45.8% of those hips required further surgery. The estimated odds ratio of needing additional surgery after simultaneous reduction was 4.04. Clinically, 79.2% of the hips were graded as McKay I, whereas radiologically only 38.8% were Severin I. The AVN rate in bilateral DDH treated surgically is greater than the rate noted in unilateral cases from the same institution undergoing identical protocols. There was no difference in AVN rates between simultaneous and sequential or between the first and second hip to be sequentially reduced. Presence of ON decreases the risk for AVN, suggesting that in bilateral cases, awaiting the appearance of the ON is an important tool to reduce the incidence of AVN. IV.

Statistical analysis of dislocations and dislocation boundaries from EBSD data.

PubMed

Moussa, C; Bernacki, M; Besnard, R; Bozzolo, N

2017-08-01

Electron BackScatter Diffraction (EBSD) is often used for semi-quantitative analysis of dislocations in metals. In general, disorientation is used to assess Geometrically Necessary Dislocations (GNDs) densities. In the present paper, we demonstrate that the use of disorientation can lead to inaccurate results. For example, using the disorientation leads to different GND density in recrystallized grains which cannot be physically justified. The use of disorientation gradients allows accounting for measurement noise and leads to more accurate results. Misorientation gradient is then used to analyze dislocations boundaries following the same principle applied on TEM data before. In previous papers, dislocations boundaries were defined as Geometrically Necessary Boundaries (GNBs) and Incidental Dislocation Boundaries (IDBs). It has been demonstrated in the past, through transmission electron microscopy data, that the probability density distribution of the disorientation of IDBs and GNBs can be described with a linear combination of two Rayleigh functions. Such function can also describe the probability density of disorientation gradient obtained through EBSD data as reported in this paper. This opens the route for determining IDBs and GNBs probability density distribution functions separately from EBSD data, with an increased statistical relevance as compared to TEM data. The method is applied on deformed Tantalum where grains exhibit dislocation boundaries, as observed using electron channeling contrast imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

Sports Injuries about the Hip: What the Radiologist Should Know.

PubMed

Hegazi, Tarek M; Belair, Jeffrey A; McCarthy, Eoghan J; Roedl, Johannes B; Morrison, William B

2016-10-01

Injuries of the hip and surrounding structures represent a complex and commonly encountered scenario in athletes, with improper diagnosis serving as a cause of delayed return to play or progression to a more serious injury. As such, radiologists play an essential role in guiding management of athletic injuries. Familiarity with hip anatomy and the advantages and limitations of various imaging modalities is of paramount importance for accurate and timely diagnosis. Magnetic resonance (MR) imaging is often the modality of choice for evaluating many of the injuries discussed, although preliminary evaluation with conventional radiography and use of other imaging modalities such as ultrasonography (US), computed tomography, and bone scintigraphy may be supplementary or preferred in certain situations. Stress fractures, thigh splints, and posterior hip dislocations are important structural injuries to consider in the athlete, initially imaged with radiographs and often best diagnosed with MR imaging. Apophyseal injuries are particularly important to consider in young athletes and may be acute or related to chronic repetitive microtrauma. Femoroacetabular impingement has been implicated in development of labral tears and cartilage abnormalities. Tear of the ligamentum teres is now recognized as a potential cause of hip pain and instability, best evaluated with MR arthrography. Greater trochanteric pain syndrome encompasses a group of conditions leading to lateral hip pain, with US playing an increasingly important role for both evaluation and image-guided treatment. Muscle injuries and athletic pubalgia are common in athletes. Lastly, snapping hip syndrome and Morel-Lavallée lesions are two less common but nonetheless important considerations. © RSNA, 2016.

Supersonic Dislocation Bursts in Silicon

DOE PAGES

Hahn, E. N.; Zhao, S.; Bringa, E. M.; ...

2016-06-06

Dislocations are the primary agents of permanent deformation in crystalline solids. Since the theoretical prediction of supersonic dislocations over half a century ago, there is a dearth of experimental evidence supporting their existence. Here we use non-equilibrium molecular dynamics simulations of shocked silicon to reveal transient supersonic partial dislocation motion at approximately 15 km/s, faster than any previous in-silico observation. Homogeneous dislocation nucleation occurs near the shock front and supersonic dislocation motion lasts just fractions of picoseconds before the dislocations catch the shock front and decelerate back to the elastic wave speed. Applying a modified analytical equation for dislocation evolutionmore » we successfully predict a dislocation density of 1.5 x 10(12) cm(-2) within the shocked volume, in agreement with the present simulations and realistic in regards to prior and on-going recovery experiments in silicon.« less

Supersonic Dislocation Bursts in Silicon

PubMed Central

Hahn, E. N.; Zhao, S.; Bringa, E. M.; Meyers, M. A.

2016-01-01

Dislocations are the primary agents of permanent deformation in crystalline solids. Since the theoretical prediction of supersonic dislocations over half a century ago, there is a dearth of experimental evidence supporting their existence. Here we use non-equilibrium molecular dynamics simulations of shocked silicon to reveal transient supersonic partial dislocation motion at approximately 15 km/s, faster than any previous in-silico observation. Homogeneous dislocation nucleation occurs near the shock front and supersonic dislocation motion lasts just fractions of picoseconds before the dislocations catch the shock front and decelerate back to the elastic wave speed. Applying a modified analytical equation for dislocation evolution we successfully predict a dislocation density of 1.5 × 1012 cm−2 within the shocked volume, in agreement with the present simulations and realistic in regards to prior and on-going recovery experiments in silicon. PMID:27264746

Supersonic Dislocation Bursts in Silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hahn, E. N.; Zhao, S.; Bringa, E. M.

Dislocations are the primary agents of permanent deformation in crystalline solids. Since the theoretical prediction of supersonic dislocations over half a century ago, there is a dearth of experimental evidence supporting their existence. Here we use non-equilibrium molecular dynamics simulations of shocked silicon to reveal transient supersonic partial dislocation motion at approximately 15 km/s, faster than any previous in-silico observation. Homogeneous dislocation nucleation occurs near the shock front and supersonic dislocation motion lasts just fractions of picoseconds before the dislocations catch the shock front and decelerate back to the elastic wave speed. Applying a modified analytical equation for dislocation evolutionmore » we successfully predict a dislocation density of 1.5 x 10(12) cm(-2) within the shocked volume, in agreement with the present simulations and realistic in regards to prior and on-going recovery experiments in silicon.« less

Dislocation dynamics simulations of interactions between gliding dislocations and radiation induced prismatic loops in zirconium

NASA Astrophysics Data System (ADS)

Drouet, Julie; Dupuy, Laurent; Onimus, Fabien; Mompiou, Frédéric; Perusin, Simon; Ambard, Antoine

2014-06-01

The mechanical behavior of Pressurized Water Reactor fuel cladding tubes made of zirconium alloys is strongly affected by neutron irradiation due to the high density of radiation induced dislocation loops. In order to investigate the interaction mechanisms between gliding dislocations and loops in zirconium, a new nodal dislocation dynamics code, adapted to Hexagonal Close Packed metals, has been used. Various configurations have been systematically computed considering different glide planes, basal or prismatic, and different characters, edge or screw, for gliding dislocations with -type Burgers vectors. Simulations show various interaction mechanisms such as (i) absorption of a loop on an edge dislocation leading to the formation of a double super-jog, (ii) creation of a helical turn, on a screw dislocation, that acts as a strong pinning point or (iii) sweeping of a loop by a gliding dislocation. It is shown that the clearing of loops is more favorable when the dislocation glides in the basal plane than in the prismatic plane explaining the easy dislocation channeling in the basal plane observed after neutron irradiation by transmission electron microscopy.

Hip Dislocation Increases Roughness of Oxidized Zirconium Femoral Heads in Total Hip Arthroplasty: An Analysis of 59 Retrievals

PubMed Central

Moussa, Mohamed E.; Esposito, Christina I.; Elpers, Marcella E.; Wright, Timothy M.; Padgett, Douglas E.

2014-01-01

The aims of this study were to assess damage on the surface of retrieved oxidized zirconium metal (OxZr) femoral heads, to measure surface roughness of scratches, and to evaluate the extent of surface effacement using scanning electron microscopy (SEM). Ceramic zirconia-toughened alumina (ZTA) heads were analyzed for comparison. OxZr femoral heads explanted for recurrent dislocation had the most severe damage (p<0.001). The median surface roughness of damaged OxZr femoral heads was 1.49μm, compared to 0.084μm for damaged ZTA heads and 0.052μm for undamaged OxZr (p<0.001). This may be of clinical concern because increased surface roughness has the potential to increase the wear of polyethylene liners articulating against these OxZr heads in THA. PMID:25443362

A continuum theory of edge dislocations

NASA Astrophysics Data System (ADS)

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

Osteochondral Autograft from the Ipsilateral Femoral Head by Surgical Dislocation for Treatment of Femoral Head Fracture Dislocation: A Case Report.

PubMed

Won, Yougun; Lee, Gi Soo; Kim, Sang Bum; Kim, Sun Joong; Yang, Kyu Hyun

2016-11-01

As anatomical reduction of the articular surface of femoral head fractures and restoration of damaged cartilage are essential for good long-term results, many treatment options have been suggested, including fixation of the fracture using various surgical exposures and implants, as well as arthroscopic irrigation and debridement, bone marrow stimulating techniques, osteochondral allograft, autograft, and autogenous chondrocyte implantation. We report a case of osteochondral autograft harvested from its own femoral articular surface through surgical hip dislocation. The osteochondral graft was harvested from the inferior non-weight-bearing articular surface and grafted to the osteochondral defect. One year later, the clinical and radiological results were good, without the collapse of the femoral head or arthritic change. This procedure introduced in our case is considered convenient and able to lessen surgical time without morbidity of the donor site associated with the harvest.

Knee Dislocations

PubMed Central

Schenck, Robert C.; Richter, Dustin L.; Wascher, Daniel C.

2014-01-01

Background: Traumatic knee dislocation is becoming more prevalent because of improved recognition and increased exposure to high-energy trauma, but long-term results are lacking. Purpose: To present 2 cases with minimum 20-year follow-up and a review of the literature to illustrate some of the fundamental principles in the management of the dislocated knee. Study Design: Review and case reports. Methods: Two patients with knee dislocations who underwent multiligamentous knee reconstruction were reviewed, with a minimum 20-year follow-up. These patients were brought back for a clinical evaluation using both subjective and objective measures. Subjective measures include the following scales: Lysholm, Tegner activity, visual analog scale (VAS), Short Form–36 (SF-36), International Knee Documentation Committee (IKDC), and a psychosocial questionnaire. Objective measures included ligamentous examination, radiographic evaluation (including Telos stress radiographs), and physical therapy assessment of function and stability. Results: The mean follow-up was 22 years. One patient had a vascular injury requiring repair prior to ligament reconstruction. The average assessment scores were as follows: SF-36 physical health, 52; SF-36 mental health, 59; Lysholm, 92; IKDC, 86.5; VAS involved, 10.5 mm; and VAS uninvolved, 2.5 mm. Both patients had excellent stability and were functioning at high levels of activity for their age (eg, hiking, skydiving). Both patients had radiographic signs of arthritis, which lowered 1 subject’s IKDC score to “C.” Conclusion: Knee dislocations have rare long-term excellent results, and most intermediate-term studies show fair to good functional results. By following fundamental principles in the management of a dislocated knee, patients can be given the opportunity to function at high levels. Hopefully, continued advances in the evaluation and treatment of knee dislocations will improve the long-term outcomes for these patients in the

“Conjugate Channeling” Effect in Dislocation Core Diffusion: Carbon Transport in Dislocated BCC Iron

PubMed Central

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 , but in a conjugate diffusion direction. This accelerated random walk arises from a simple crystallographic channeling effect. is a function of the Burgers vector b, but not , 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. PMID:23593255

Dynamic long leg casting fixation for treating 12- to 18-month-old infants with developmental dysplasia of the hip.

PubMed

Cai, Zhencun; Li, Lianyong; Zhang, Lijun; Ji, Shijun; Zhao, Qun

2017-02-01

Objective To evaluate the effect of dynamic long leg casting in paediatric patients with developmental dysplasia of hip (DDH) diagnosed at 12-18 months. Methods The adductor tenotomy, closed reduction, and dynamic long leg casting method was adopted to treat paediatric patients with DDH. The hips were divided into four groups according to the Tonnis radiographic dislocation classification. Groups were also classified according to the baseline acetabular index (AI): 30°-35°, 36°-40°, and > 40°. The outcomes of the reductions were evaluated according to McKay's hip function criteria and Severin's radiological criteria. Results A total of 246 patients (339 hips) had complete follow-up data. After 3 months of orthosis fixation, the results were satisfactory in 264 hips (77.88%). Hip function was rated as 'excellent' or 'good' in 43 of 51 (84.31%) Tonnis type 1 hips, 125 of 155 (80.65%) type 2 hips, 70 of 90 (77.78%) type 3 hips, and 34 of 43 (79.07%) type 4 hips. The higher the baseline AI, the lower the rates of 'excellent' and 'good' hip function. Favourable radiological results (Severin types I and II) were found in 266 of 339 (78.47) hips. Conclusions Dynamic long leg casting is an effective method for treating patients with DDH aged 12-18 months at diagnosis.

[APPLICATION AND EFFECTIVENESS OF BIOLOGICAL TYPE ACETABULAR CUP IN ADULT Crowe TYPE IV DEVELOPMENTAL DYSPLASIA OF THE HIP].

PubMed

Xu, Ning; Sun, Junying; Zhao, Xijiang; Wang, Tao

2016-01-01

To investigate the application and effectiveness of the biological type acetabular cup(diameter < 44 mm) in adult Crowe type IV developmental dysplasia of the hip (DDH). Between April 2001 andAugust 2013, biological type acetabular cup was used in total hip arthroplasty for the treatment of Crowe type IV DDH in16 cases (20 hips). There were 3 males and 13 females, aged 31-69 years (mean, 49 years). Unilateral hip was involved in 12cases, and bilateral hips in 4 cases. The patients showed pain of the hip joint and inequality of lower limb (shortening ofaffected limb 1.8-6.0 cm in length, 3.5 cm on average). Acetabular deformity, the relationship and the severity of femoralhead dislocation were comfirmed on the X-ray films. The preoperative Harris score was 34.0 ± 6.9. All patientsachieved healing of incision by first intention, with no complication of infection or neurovascular injury. Sixteen caseswere followed up 4-12 years (mean, 7.5 years). At 2 weeks after operation, dislocation occurred in 2 cases, and were fixedwith plaster for 3 weeks after reduction of the hip. Postoperative X-ray films showed complete reduction of femoral head;the average acetabular coverage of the cup of the weight-bearing area was 98.5% (range, 98.2%-99.1%). The cup from theRanawat triangle was 4.6-7.0 mm (mean, 5.8 mm) in medial shifting, and was 4.5-7.9 mm (mean, 6.2 mm) in elevation,it located at cup lateral surface area inside the iliopectineal line and the Kohler line (< 40%); the cup abduction angle was(45 ± 5)degrees, and the anteversion angle was (10 ± 5)degrees. The other patients had no prosthesis loosening except 1 patient havingextensive acetabular prosthesis loosening because of acetabular osteolysis at 12 years after operation. The hip Harris scorewas significantly improved to 85.0 ± 7.5 at 1 year after operation (t = 14.34, P = 0.01). The acetabular grindingprocess to retain enough bone combined with a small cup of-biological prosthesis treating adult Crowe type IV DDH

Quantifying the effect of hydrogen on dislocation dynamics: A three-dimensional discrete dislocation dynamics framework

NASA Astrophysics Data System (ADS)

Gu, Yejun; El-Awady, Jaafar A.

2018-03-01

We present a new framework to quantify the effect of hydrogen on dislocations using large scale three-dimensional (3D) discrete dislocation dynamics (DDD) simulations. In this model, the first order elastic interaction energy associated with the hydrogen-induced volume change is accounted for. The three-dimensional stress tensor induced by hydrogen concentration, which is in equilibrium with respect to the dislocation stress field, is derived using the Eshelby inclusion model, while the hydrogen bulk diffusion is treated as a continuum process. This newly developed framework is utilized to quantify the effect of different hydrogen concentrations on the dynamics of a glide dislocation in the absence of an applied stress field as well as on the spacing between dislocations in an array of parallel edge dislocations. A shielding effect is observed for materials having a large hydrogen diffusion coefficient, with the shield effect leading to the homogenization of the shrinkage process leading to the glide loop maintaining its circular shape, as well as resulting in a decrease in dislocation separation distances in the array of parallel edge dislocations. On the other hand, for materials having a small hydrogen diffusion coefficient, the high hydrogen concentrations around the edge characters of the dislocations act to pin them. Higher stresses are required to be able to unpin the dislocations from the hydrogen clouds surrounding them. Finally, this new framework can open the door for further large scale studies on the effect of hydrogen on the different aspects of dislocation-mediated plasticity in metals. With minor modifications of the current formulations, the framework can also be extended to account for general inclusion-induced stress field in discrete dislocation dynamics simulations.

Hip Joint Replacement Using Monofilament Polypropylene Surgical Mesh: An Animal Model

PubMed Central

Białecki, Jacek; Klimowicz-Bodys, Małgorzata Dorota; Wierzchoś, Edward; Kołomecki, Krzysztof

2014-01-01

Hip joint dysplasia is a deformation of the articular elements (pelvic acetabulum, head of the femur, and/or ligament of the head of the femur) leading to laxity of the hip components and dislocation of the femoral head from the pelvic acetabulum. Diagnosis is based on symptoms observed during clinical and radiological examinations. There are two treatment options: conservative and surgical. The classic surgical procedures are juvenile pubic symphysiodesis (JPS), triple pelvic osteotomy (TPO), total hip replacement (THR), and femoral head and neck resection (FHNE). The aim of this experiment was to present an original technique of filling the acetabulum with a polypropylene implant, resting the femoral neck directly on the mesh. The experiment was performed on eight sheep. The clinical value of the new surgical technique was evaluated using clinical, radiological, and histological methods. This technique helps decrease the loss of limb length by supporting the femoral neck on the mesh equivalent to the femoral head. It also reduces joint pain and leads to the formation of stable and mobile pseudarthrosis. The mesh manifested osteoprotective properties and enabled the formation of a stiff-elastic connection within the hip joint. The method is very cost-effective and the technique itself is simple to perform. PMID:24987672

Hip joint replacement using monofilament polypropylene surgical mesh: an animal model.

PubMed

Białecki, Jacek; Majchrzycki, Marian; Szymczak, Antoni; Klimowicz-Bodys, Małgorzata Dorota; Wierzchoś, Edward; Kołomecki, Krzysztof

2014-01-01

Hip joint dysplasia is a deformation of the articular elements (pelvic acetabulum, head of the femur, and/or ligament of the head of the femur) leading to laxity of the hip components and dislocation of the femoral head from the pelvic acetabulum. Diagnosis is based on symptoms observed during clinical and radiological examinations. There are two treatment options: conservative and surgical. The classic surgical procedures are juvenile pubic symphysiodesis (JPS), triple pelvic osteotomy (TPO), total hip replacement (THR), and femoral head and neck resection (FHNE). The aim of this experiment was to present an original technique of filling the acetabulum with a polypropylene implant, resting the femoral neck directly on the mesh. The experiment was performed on eight sheep. The clinical value of the new surgical technique was evaluated using clinical, radiological, and histological methods. This technique helps decrease the loss of limb length by supporting the femoral neck on the mesh equivalent to the femoral head. It also reduces joint pain and leads to the formation of stable and mobile pseudarthrosis. The mesh manifested osteoprotective properties and enabled the formation of a stiff-elastic connection within the hip joint. The method is very cost-effective and the technique itself is simple to perform.

Habitual dislocation of patella: A review

PubMed Central

Batra, Sumit; Arora, Sumit

2014-01-01

Habitual dislocation of patella is a condition where the patella dislocates whenever the knee is flexed and spontaneously relocates with extension of the knee. It is also termed as obligatory dislocation as the patella dislocates completely with each flexion and extension cycle of the knee and the patient has no control over the patella dislocating as he or she moves the knee1. It usually presents after the child starts to walk, and is often well tolerated in children, if it is not painful. However it may present in childhood with dysfunction and instability. Very little literature is available on habitual dislocation of patella as most of the studies have combined cases of recurrent dislocation with habitual dislocation. Many different surgical techniques have been described in the literature for the treatment of habitual dislocation of patella. No single procedure is fully effective in the surgical treatment of habitual dislocation of patella and a combination of procedures is recommended. PMID:25983506

Using O*NET in Dislocated Worker Retraining: The Toledo Dislocated Worker Consortium Project.

ERIC Educational Resources Information Center

Sommers, Dixie; Austin, James

A project used the Occupational Information Network (O*NET) to assist eligible dislocated workers in determining whether training offered by the Toledo Dislocated Worker Consortium fit their needs. More specifically, O*NET was used to help the dislocated workers understand whether they had knowledge and skills that were transferable into the…

Reduction of metallosis in hip implant using thin film coating

NASA Astrophysics Data System (ADS)

Rajeshshyam, R.; Chockalingam, K.; Gayathri, V.; Prakash, T.

2018-04-01

Hip implant finds its emerging attraction due to it continuous demand over the years. The hip implants (femoral head) and acetabulum cup) mainly fabricated by metals such as stainless steel, cobalt chrome and titanium alloys, other than that ceramics and polyethylene have been used. The metal-on-metal hip implant was found to be best implant material for most of the surgeons due to its high surface finish, low wear rate and low chance of dislocation from its position after implanting. Where in metal based hip implant shows less wear rate of 0.01mm3/year. Metal-on-metal implant finds its advantage over other materials both in its mechanical and physical stability against human load. In M-O-M Cobalt- chromium alloys induce metal allergy. The metal allergy (particulate debris) that is generated by wear, fretting, fragmentation and which is unavoidable when a prosthesis is implanted, can induce an inflammatory reaction in some circumstances. The objectives of this research to evaluate thin film coating with Nano particle additives to reduce the wear leads to regarding metal ion release. Experimental results reveals that thin film Sol-Gel coating with 4wt. % of specimen reduced the cobalt and chromium ion release and reduces the wear rate. Wear rate reduced by 98% for 4wt. % graphene in 20N and 95% for 4wt. % graphene in 10N.

An update on surgical approaches in hip arthoplasty: lateral versus posterior approach.

PubMed

Mukka, Sebastian S; Sayed-Noor, Arkan S

2014-10-02

In this update we searched the literature about the outcome of the lateral versus posterior approach in hip arthoplasty for osteoarthritis (OA) and femoral neck fracture (FNF) patients. The available evidence shows that the use of posterior approach in OA patients is associated with lower mortality and better functional outcome while the use of lateral approach in FNF patients gives lower dislocation rate. We recommend therefore the use of posterior approach in OA patients and lateral approach in FNF patients.

Three-dimensional formulation of dislocation climb

NASA Astrophysics Data System (ADS)

Gu, Yejun; Xiang, Yang; Quek, Siu Sin; Srolovitz, David J.

2015-10-01

We derive a Green's function formulation for the climb of curved dislocations and multiple dislocations in three-dimensions. In this new dislocation climb formulation, the dislocation climb velocity is determined from the Peach-Koehler force on dislocations through vacancy diffusion in a non-local manner. The long-range contribution to the dislocation climb velocity is associated with vacancy diffusion rather than from the climb component of the well-known, long-range elastic effects captured in the Peach-Koehler force. Both long-range effects are important in determining the climb velocity of dislocations. Analytical and numerical examples show that the widely used local climb formula, based on straight infinite dislocations, is not generally applicable, except for a small set of special cases. We also present a numerical discretization method of this Green's function formulation appropriate for implementation in discrete dislocation dynamics (DDD) simulations. In DDD implementations, the long-range Peach-Koehler force is calculated as is commonly done, then a linear system is solved for the climb velocity using these forces. This is also done within the same order of computational cost as existing discrete dislocation dynamics methods.

The effect of isolated dislocations on substrate and device properties in low-dislocation czochralski GaAs

NASA Astrophysics Data System (ADS)

Hunter, A. T.; Kimura, H.; Olsen, H. M.; Winston, H. V.

1986-07-01

Czochralski GaAs grown with In incorporated into the melt has large regions with fewer than 100 cm-2 dislocations. We have examined the effect of these dislocations on substrate and device properties. Infrared transmission images reveal dark filaments of high EL2 concentration a few tens of microns in diameter surrounding dislocations, Cathodo and photoluminescence images show orders of magnitude contrast in band-edge luminescence intensity near dislocations. Single dislocations appear to be surrounded by bright rings ˜200 μm in diameter in luminescence images, with dark spots 50 to 75 μm across centered on the dislocation. More complex luminescence structures with larger dark regions (˜150 μ across) and central bright spots are centered on small dislocation clusters. Differences in lifetime of photogenerated electrons or holes are the most likely cause of the luminescence contrast. Anneals typical of our post-implant processing substantially lower the luminescence contrast, suggesting the defect lowering the lifetime is removed by annealing. This may partially explain why we do not observe any effect of dislocation proximity on the properties of devices made in the material, in spite of the enormous luminescence contrast observed near dislocations.

Total hip arthroplasty using a cementless dual-mobility cup provides increased stability and favorable gait parameters at five years follow-up.

PubMed

Acker, A; Fischer, J-F; Aminian, K; Lécureux, E; Jolles, B M

2017-02-01

Rates of dislocation following primary total hip arthroplasty (THA) vary from 0.5 to 10%. Dual-mobility cups in THA demonstrate increased stability. Clinical outcomes following THA with dual-mobility cups have been reported, but gait has not been assessed. Therefore we performed a retrospective case control study to answer: (1) is gait better in patients following THA with a dual-mobility cup than in frail, elderly patients of the same age? (2) Are clinical outcomes better in patients following THA with a dual-mobility cup than in frail, elderly patients? (3) What is the dislocation rate following THA with a dual-mobility cup? We hypothesized that patients who underwent THA with a dual-mobility cup have a better gait compared to frail, elderly patients of the same age. Twenty patients (22 hips), mean age 79.9±7.7 (range, 62.3-88.3) years were assessed in this retrospective case-control series 5.6±1.4 (range: 4.1-8.8) years following dual-mobility cup THA. A reference group consisted of 72 "frail elderly" patients in a rehabilitation hospital for health problems unrelated to the lower limb, with no lower limb surgery or neurological conditions. Temporal and spatial gait performance were measured with four miniature gyroscopes, mounted on each thigh and calf, while patients walked freely along a 30m corridor. Harris Hip Score, WOMAC, radiological outcomes, and dislocation rate were determined. All gait parameters were better in the dual-mobility group compared to the frail elderly group. The dual-mobility group had a higher cadence (100.3 steps/minute versus 75.6 steps/minute), shorter (relative to gait cycle time) stance (61.6% versus 67.8%), shorter (relative to gait cycle time) double stance (23.3% versus 36.0%), longer stride (1.13m versus 0.80m), and faster walking speed (0.96m/s versus 0.52m/s). Range of motion of the shank, thigh and knee were better in the dual-mobility group. Harris Hip Score was 87.6±13.9 (range 51-100) and WOMAC score was 11.3±12

Dislocations in bilayer graphene

NASA Astrophysics Data System (ADS)

Butz, Benjamin; Dolle, Christian; Niekiel, Florian; Weber, Konstantin; Waldmann, Daniel; Weber, Heiko B.; Meyer, Bernd; Spiecker, Erdmann

2014-01-01

Dislocations represent one of the most fascinating and fundamental concepts in materials science. Most importantly, dislocations are the main carriers of plastic deformation in crystalline materials. Furthermore, they can strongly affect the local electronic and optical properties of semiconductors and ionic crystals. In materials with small dimensions, they experience extensive image forces, which attract them to the surface to release strain energy. However, in layered crystals such as graphite, dislocation movement is mainly restricted to the basal plane. Thus, the dislocations cannot escape, enabling their confinement in crystals as thin as only two monolayers. To explore the nature of dislocations under such extreme boundary conditions, the material of choice is bilayer graphene, the thinnest possible quasi-two-dimensional crystal in which such linear defects can be confined. Homogeneous and robust graphene membranes derived from high-quality epitaxial graphene on silicon carbide provide an ideal platform for their investigation. Here we report the direct observation of basal-plane dislocations in freestanding bilayer graphene using transmission electron microscopy and their detailed investigation by diffraction contrast analysis and atomistic simulations. Our investigation reveals two striking size effects. First, the absence of stacking-fault energy, a unique property of bilayer graphene, leads to a characteristic dislocation pattern that corresponds to an alternating ABAC change of the stacking order. Second, our experiments in combination with atomistic simulations reveal a pronounced buckling of the bilayer graphene membrane that results directly from accommodation of strain. In fact, the buckling changes the strain state of the bilayer graphene and is of key importance for its electronic properties. Our findings will contribute to the understanding of dislocations and of their role in the structural, mechanical and electronic properties of bilayer and

Dislocations in bilayer graphene.

PubMed

Butz, Benjamin; Dolle, Christian; Niekiel, Florian; Weber, Konstantin; Waldmann, Daniel; Weber, Heiko B; Meyer, Bernd; Spiecker, Erdmann

2014-01-23

Dislocations represent one of the most fascinating and fundamental concepts in materials science. Most importantly, dislocations are the main carriers of plastic deformation in crystalline materials. Furthermore, they can strongly affect the local electronic and optical properties of semiconductors and ionic crystals. In materials with small dimensions, they experience extensive image forces, which attract them to the surface to release strain energy. However, in layered crystals such as graphite, dislocation movement is mainly restricted to the basal plane. Thus, the dislocations cannot escape, enabling their confinement in crystals as thin as only two monolayers. To explore the nature of dislocations under such extreme boundary conditions, the material of choice is bilayer graphene, the thinnest possible quasi-two-dimensional crystal in which such linear defects can be confined. Homogeneous and robust graphene membranes derived from high-quality epitaxial graphene on silicon carbide provide an ideal platform for their investigation. Here we report the direct observation of basal-plane dislocations in freestanding bilayer graphene using transmission electron microscopy and their detailed investigation by diffraction contrast analysis and atomistic simulations. Our investigation reveals two striking size effects. First, the absence of stacking-fault energy, a unique property of bilayer graphene, leads to a characteristic dislocation pattern that corresponds to an alternating AB B[Symbol: see text]AC change of the stacking order. Second, our experiments in combination with atomistic simulations reveal a pronounced buckling of the bilayer graphene membrane that results directly from accommodation of strain. In fact, the buckling changes the strain state of the bilayer graphene and is of key importance for its electronic properties. Our findings will contribute to the understanding of dislocations and of their role in the structural, mechanical and electronic

Effects of dislocations on polycrystal anelasticity

NASA Astrophysics Data System (ADS)

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

Recombination properties of dislocations in GaN

NASA Astrophysics Data System (ADS)

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.

[Classification and Treatment of Sacroiliac Joint Dislocation].

PubMed

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

NASA Astrophysics Data System (ADS)

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.

Fast Fourier transform discrete dislocation dynamics

NASA Astrophysics Data System (ADS)

Graham, J. T.; Rollett, A. D.; LeSar, R.

2016-12-01

Discrete dislocation dynamics simulations have been generally limited to modeling systems described by isotropic elasticity. Effects of anisotropy on dislocation interactions, which can be quite large, have generally been ignored because of the computational expense involved when including anisotropic elasticity. We present a different formalism of dislocation dynamics in which the dislocations are represented by the deformation tensor, which is a direct measure of the slip in the lattice caused by the dislocations and can be considered as an eigenstrain. The stresses arising from the dislocations are calculated with a fast Fourier transform (FFT) method, from which the forces are determined and the equations of motion are solved. Use of the FFTs means that the stress field is only available at the grid points, which requires some adjustments/regularizations to be made to the representation of the dislocations and the calculation of the force on individual segments, as is discussed hereinafter. A notable advantage of this approach is that there is no computational penalty for including anisotropic elasticity. We review the method and apply it in a simple dislocation dynamics calculation.

[Comparison of early clinical effects of two hip prosthesis designs between ceramics to ceramics and metal to polyethylene].

PubMed

Yang, Li-qing; Li, Xi; Fu, Qin; Wang, Cheng

2013-07-01

To retrospectively study early therapeutic effects of the ceramics to ceramics prosthesis design in treating hip disease. From October 2007 to September 2010, 42 patients (44 hips) with hip disease underwent replacement of total hip. Hip prosthesis designs included the Pinnacle ceramics to ceramics and the Duraloc metal to polyethylene,produced by DePuy Company, all were non-bone cement type of artificial hip joint. Twenty patients (22 hips) were performed with ceramics to ceramics total hip prosthesis (CoC group, there were 12 males and 8 females, aged from 21 to 49 years) and 22 patients (22 hips) were performed with metal to polyethylene total hip prosthesis (MoP group, there were 13 males and 9 females, aged from 42 to 55 years). All the surgical approachs were posterolateral, and the routine anticoagulation and the corresponding functional exercise were performed after operation. The follow-up time was 6 months at least including clinical and radiographic observation. Measured the motion of joint and evaluated the function of hip joint according to Harris classification. All clinical effects were satisfactory and no dislocation ,loosening,infection, deep venous thrombosis and other complications occurred. There was no statistical significance in Harris scoring and the motion of joint between two groups before and after operation (P>0.05). The clinical effect of ceramics to ceramics prosthesis design in improving clinical symptoms and the motion of joint is coordinate with metal to polyethylene total hip prosthesis, however, its advantages and long-term efficacy need further observing. The ceramics to ceramics prosthesis design may be a good choice for the young patients with hip disease because of its good wear resistance.

Theory of interacting dislocations on cylinders.

PubMed

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.

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

NASA Astrophysics Data System (ADS)

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.

Medium-term outcome in patients treated with total hip arthroplasty using a modular femoral stem.

PubMed

Dagnino, Augusto; Grappiolo, Guido; Benazzo, Franco M; Learmonth, Ian D; Spotorno, Lorenzo; Portinaro, Nicola

2012-01-01

The clinical, radiographic and quality of life results of total hip arthroplasty using the MODULUS cementless modular femoral stem were reviewed. 48 patients who had a total hip arthroplasty using the MODULUS femoral stem were identified. Six had bilateral procedures, resulting in 60 hips with complete clinical and radiographic data. Mean age at implantation was 50 years (range 33 to 82). Mean follow-up was 59 months (range 50 months to 73). There were two early post-operative dislocations (within 2 days). One patient required further surgery to remove heterotopic bone. Mean Harris Hip Score increased from 37 points preoperatively (range, 7 to 66) to 89 points at final review (range, 65 to 100 points). Radiographic evaluation revealed that all implants were stable without evidence of osteolysis but three patients (5%) exhibited heterotopic ossification. Quality of life was evaluated with the SF36. The physical component increased from 29.2 points (range, 18.5 to 46.0) to 51.7 points (range 42.9 to 60.6) and the mental component from 375 points (range, 19.5 to 50.0) to 50 points (range 32,8 to 62.0).

Long-term clinical and radiographic outcome of the PPF system in ceramic-on-polyethylene hip bearings.

PubMed

Legenstein, R; Huber, W; Ungersboeck, A; Boesch, P

2006-01-01

From 1990 to 1991 we implanted 176 non-cemented proximal press-fit (PPF) total hip arthroplasties (THA) with ceramic-on-polyethylene articulation in 170 patients. Of these, 119 patients (122 THA) were followed from 104 to 129 months. Four cups have been revised for aseptic loosening, but revealed no radiolucencies of the stem. Two infections and two dislocations occurred. The median postoperative Harris hip score was 91. Ninety-eight per cent of the patients were satisfied with the outcome, 83% were free of pain and 67% walked without a limp. Serial radiographs showed stable fixation with bone ongrowth in nearly all arthroplasties except for four cups. Stem radiolucencies were first seen within 12 months, but were of no clinical relevance. Proximal periprosthetic bone resorption of the stem was seen in 18%. Radiolucencies occurred because of polyethylene debris-induced granulomas. The PPF system yields satisfactory long-term results in patients with primary and secondary hip osteoarthritis and dysplasia.

[Joint dislocation after total knee arthroplasty as an ankle fracture complication. Case report].

PubMed

Hrubina, M; Skoták, M

2012-01-01

Joint dislocation after total knee arthroplasty is a rare complication. It is described as the result of ligamentous instability. Here we report the case of an 82-year-old women who underwent primary total knee arthroplasty (TKA) for advanced primary grade III gonarthrosis. At 3 post-operative months the joint was stable and painless, with radiographic evidence of good TKA alignment and integration. At 4 months the patient suffered injury to the ankle involving a bimalleolar fracture and damage to knee soft tissues. The fracture was surgically treated. Subsequently, dorsal tibial dislocation was manifested. This was managed by individual intramedullary nail arthrodesis. At 8 months following the operation, the knee condition was satisfactory, with rigid arthrodesis and leg shortening of 4 cm. The patient was satisfied because she was free of pain and able to walk. Arthrodesis of the knee joint with an individual nail is an option for a definitive treatment of TKA instability. When other joints, such as ankle or hip joints, are injured, it is recommended to pay attention also to any TKA implanted previously because of potential development of instability or infection.

Misfit dislocation patterns of Mg-Nb interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Youxing; Shao, Shuai; Liu, Xiang-Yang

The role of heterogeneous interfaces in improving mechanical properties of polycrystalline aggregates and laminated composites has been well recognized with interface structure being of fundamental importance in designing composites containing multiple interfaces. In this paper, taking the Mg (hexagonal close-packed (hcp))/Nb (body-centered cubic (bcc)) interface as an example, we develop Mg-Nb interatomic potentials for predicting atomic configurations of Mg/Nb interfaces. We systematically characterize interface dislocations of Mg/Nb interfaces with Nishiyama-Wassermann (NW) and Kurdjumov-Sachs (KS) orientation relationships and propose a generalized procedure of characterizing interface structure by combining atomistic simulation and interface dislocation theory, which is applicable for not only hcp/bccmore » interfaces, but also other systems with complicated interface dislocation configurations.Here, in Mg/Nb, interface dislocation networks of two types of interfaces are significantly different although they originate from partial dislocations of similar character: the NW interface is composed of three sets of partial dislocations, while the KS interface is composed of four sets of interface dislocations - three sets of partial dislocations and one set of full dislocations that forms from the reaction of two close partial dislocations.« less

Probing the character of ultra-fast dislocations

DOE PAGES

Rudd, R. E.; Ruestes, C. J.; Bringa, E. M.; ...

2015-11-23

Plasticity is often controlled by dislocation motion, which was first measured for low pressure, low strain rate conditions decades ago. However, many applications require knowledge of dislocation motion at high stress conditions where the data are sparse, and come from indirect measurements dominated by the effect of dislocation density rather than velocity. Here we make predictions based on atomistic simulations that form the basis for a new approach to measure dislocation velocities directly at extreme conditions using three steps: create prismatic dislocation loops in a near-surface region using nanoindentation, drive the dislocations with a shockwave, and use electron microscopy tomore » determine how far the dislocations moved and thus their velocity at extreme stress and strain rate conditions. We report on atomistic simulations of tantalum that make detailed predictions of dislocation flow, and find that the approach is feasible and can uncover an exciting range of phenomena, such as transonic dislocations and a novel form of loop stretching. Furthermore, the simulated configuration enables a new class of experiments to probe average dislocation velocity at very high applied shear stress.« less

Is transverse acetabular ligament an anatomical landmark to reliably orient the cup in primary total hip arthroplasty?

PubMed

Viste, A; Chouteau, J; Testa, R; Chèze, L; Fessy, M-H; Moyen, B

2011-05-01

Accurate positioning of the acetabular cup in primary total hip arthroplasty is critical to decrease the rate of dislocation. Inaccurate orientation of the cup is the most common error during this procedure. Target acetabular orientation is still controversial. An original study found a dislocation rate of 0.6% when the cup was aligned with the transverse acetabular ligament (TAL). TAL is a patient-specific anatomical landmark and a tool for cup orientation. Eight cadaveric pelves (14 hips included for study) were harvested in toto at our research laboratory. Anatomical versions of the TAL, labrum and horns were measured in relation to the anterior pelvic plane. A navigator sensor and an optoelectronic device (Motion Analysis™) were used. Anatomical versions of the TAL, horns and labrum averaged 1.9° (range, -8° to +13.3°), 3° (range, -12.2° to 14°), and 26.3° (range, 17.4° to 41.8°), respectively. To our knowledge, this is the first study to report the orientation of the periacetabular soft-tissues. TAL anteversion was outside the safe zone described by Lewinnek, while labrum anteversion was within this safe-zone. We discuss the reference used, Lewinnek's safe zone, and functional orientation of the implants. Lewinnek's safe-zone does not seem to be valid. The TAL seems to be a specific reference for each patient but its reliability must still be confirmed as an adequate reference for positioning the cup in total hip arthroplasty. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Sex and Growth Effect on Pediatric Hip Injuries Presenting to Sports Medicine Clinic

PubMed Central

Stracciolini, Andrea; Yen, Yi-Meng; d'Hemecourt, Pierre A.; Lewis, Cara L.; Sugimoto, Dai

2016-01-01

Background To compare sports-related hip injuries based on sex and age in a cohort of young athletes. Methods 5% random probability sample of all new patients’ charts over a ten-year time period was selected for investigation. The most common hip injury diagnoses, sport at time of injury, mechanism (acute/traumatic versus overuse), and types (bony versus soft tissue) were compared by sex and age (pre-adolescent versus adolescent). Descriptive and chi-square analyzes were performed. The interaction of sex and age with regard to hip injury over time was examined by a two-way (sex, age) analysis of variance (ANOVA). Results 2,133 charts were reviewed; N=87 hip injuries. Leading diagnoses for males included labral tear (23.1%), avulsion fracture (11.5%), slipped capital femoral epiphysis (11.5%), dislocation (7.7%) and tendonitis (7.7%). Leading diagnoses for females were labral tear (59.0%), tendonitis (14.8%), snapping hip syndrome (6.6%), strain (4.9%) and bursitis (4.9%). Five most common sports/activities at time of hip injury were dancing/ballet (23.0%), soccer (18.4%), gymnastics (9.2%), ice hockey (8.1%), and track and fields (6.9%). Growth/maturation by sex showed a greater proportion of the total hip injuries (38.5%) compared to females (8.2%) during pre-adolescence (5-12 years). However, in adolescence (13-17 years), hip injury proportion was significantly greater in females (91.8%), as compared to males (61.5%; P<0.001). Injury mechanism and type differed by sex with females sustaining more chronic/overuse (95.1%) and soft tissue type injuries (93.4%), as compared to males (50.0% and 53.8%, respectively; P<0.001). Females were found to have a sharper increase in hip injury proportion as they progress through puberty as compared to males (ANOVA sex-by-age interaction; P<0.001). Conclusions Hip injury mechanism and type differed significantly between males and females during growth. Notably, the proportion of hip injuries in the young female athletes showed

Sex and growth effect on pediatric hip injuries presenting to sports medicine clinic.

PubMed

Stracciolini, Andrea; Yen, Yi-Meng; d'Hemecourt, Pierre A; Lewis, Cara L; Sugimoto, Dai

2016-07-01

To compare sports-related hip injuries on the basis of sex and age in a cohort of young athletes. A 5% random probability sample of all new patients' charts over a 10-year time period was selected for investigation. The most common hip injury diagnoses, sport at time of injury, mechanism (acute/traumatic vs. overuse), and types (bony vs. soft tissue) were compared by sex and age (preadolescent vs. adolescent). Descriptive and χ-analyses were carried out. The interaction of sex and age with respect to hip injury over time was examined by two-way (sex, age) analysis of variance. A total of 2133 charts were reviewed; N=87 hip injuries. The main diagnoses for males included labral tear (23.1%), avulsion fracture (11.5%), slipped capital femoral epiphysis (11.5%), dislocation (7.7%), and tendonitis (7.7%). The main diagnoses for females were labral tear (59.0%), tendonitis (14.8%), snapping hip syndrome (6.6%), strain (4.9%), and bursitis (4.9%). The five most common sports/activities at the time of hip injury were dancing/ballet (23.0%), soccer (18.4%), gymnastics (9.2%), ice hockey (8.1%), and track and field (6.9%). Age by sex comparisons showed a greater proportion of the total hip injuries (38.5%) in males compared with females (8.2%) during preadolescence (5-12 years). However, in adolescence (13-17 years), the hip injury proportion was significantly higher in females (91.8%) compared with males (61.5%; P<0.001). Injury mechanism and type differed by sex, with females sustaining more chronic/overuse (95.1%) and soft tissue type injuries (93.4%) compared with males (50.0 and 53.8%, respectively; P<0.001). Females were found to have a sharper increase in hip injury proportion as they progressed through puberty compared with males (analysis of variance sex-by-age interaction; P<0.001). Hip injury mechanism and type differed significantly between males and females during growth. Notably, the proportion of hip injuries in the young female athletes showed a

Chronic bilateral dislocation of temporomandibular joint.

PubMed

Shakya, S; Ongole, R; Sumanth, K N; Denny, C E

2010-01-01

Dislocation of the condyle of the mandible is a common condition that may occur in an acute or chronic form. It is characterised by inability to close the mouth with or without pain. Dislocation has to be differentiated from subluxation which is a self reducible condition. Dislocation can occur in any direction with anterior dislocation being the commonest one. Various predisposing factors have been associated with dislocation like muscle fatigue and spasm, the defect in the bony surface like shallow articular eminence, and laxity of the capsular ligament. People with defect in collagen synthesis like Ehler Danlos syndrome, Marfan syndrome are said to be genetically predisposed to this condition. Various treatment modalities have been used ranging from conservative techniques to surgical methods. Acute dislocations can be reduced manually or with conservative approach and recurrent and chronic cases can be reduced by surgical intervention. Though the dislocation in our case was 4 months a simple manual reduction proved to be successful. We believe that manual reduction can be attempted as first line of treatment prior to surgical intervention.

[Palmar lunate dislocation].

PubMed

Isenberg, J; Prokop, A; Schellhammer, F; Helling, H J

2002-12-01

Palmar lunate dislocation as the end stage of a perilunate dislocation is a very uncommon injury. Having treated 19,534 hospitalized patients between 1 January 1986 and 1 October 2001 the diagnosis was recorded in four male trauma patients (33, 36, 37 and 62 years old). Among the operatively treated carpal dislocations and carpal fracture dislocations those of the lunate were seen in five per cent. The dislocation was caused in by an acute hyperextension injury resulting of falls from heights in three cases, and of a motorcycle accident in a further case. In two of these cases a complete palmar lunate dislocation was analysed that were produced by fall from seven meters heights of a young craftsman and by accident of a motorcyclist. First using a longitudinal palmar approach in both cases a revision of the hemorrhagic carpal canal was performed urgently, the largely denuded lunate was reduced and the repair of identified ligamentous structures was performed by means of sutures respectively suture anchors. Reduction was stabilized with Kirschner wires. Afterwards performed computed tomography identified the result of reduction and associated defects (subluxation distal radioulnar joint). In one patient a soft tissue infection prevented the dorsal ligamentous repair. In spite of a consequent after-treatment and a good functional result a scapho-lunate dissociation was proved. An avascular defect of the lunate could be excluded by magnetic resonance imaging. In case of a secondary performed dorsal repair a persisting carpal stabilization with a satisfactory functional result could achieved. At second hand an advanced carpal collapse was proved. If reduction cannot be achieved by closed manipulation or a loss of reduction is shown, open reduction is indicated first by a palmar approach. An additional dorsal ligamentous repair seems to be necessary. Transfixation by Kirschner wires and suture anchors stabilize the restored anatomic relationships. Wrist immobilization in

Worker Dislocation. Case Studies of Causes and Cures.

ERIC Educational Resources Information Center

Cook, Robert F., Ed.

Case studies were made of the following dislocated worker programs: Cummins Engine Company Dislocated Worker Project; GM-UAW Metropolitan Pontiac Retraining and Employment Program; Minnesota Iron Range Dislocated Worker Project; Missouri Dislocated Worker Program Job Search Assistance, Inc.; Hillsborough, North Carolina, Dislocated Worker Project;…

Dislocation mechanisms in stressed crystals with surface effects

NASA Astrophysics Data System (ADS)

Wu, Chi-Chin; Crone, Joshua; Munday, Lynn; Discrete Dislocation Dynamics Team

2014-03-01

Understanding dislocation properties in stressed crystals is the key for important processes in materials science, including the strengthening of metals and the stress relaxation during the growth of hetero-epitaxial structures. Despite existing experimental approaches and theories, many dislocation mechanisms with surface effects still remain elusive in experiments. Even though discrete dislocation dynamics (DDD) simulations are commonly employed to study dislocations, few demonstrate sufficient computational capabilities for massive dislocations with the combined effects of surfaces and stresses. Utilizing the Army's newly developed FED3 code, a DDD computation code coupled with finite elements, this work presents several dislocation mechanisms near different types of surfaces in finite domains. Our simulation models include dislocations in a bended metallic cantilever beam, near voids in stressed metals, as well as threading and misfit dislocations in as-grown semiconductor epitaxial layers and their quantitative inter-correlations to stress relaxation and surface instability. Our studies provide not only detailed physics of individual dislocation mechanisms, but also important collective dislocation properties such as dislocation densities and strain-stress profiles and their interactions with surfaces.

Hip lateralisation in children with bilateral spastic cerebral palsy treated with botulinum toxin type A: a 2-year follow-up.

PubMed

Jung, N H; Heinen, F; Westhoff, B; Doederlein, L; Reissig, A; Berweck, S; Linder-Lucht, M; Schandelmaier, S; Mall, V

2011-02-01

We investigated the effect of BoNT/A injection on hip lateralisation in children with bilateral spastic cerebral palsy and bilateral adductor spasticity. Pelvic radiographs using Reimers' migration index (MI) were evaluated from 27 children (n=9 females, n=18 males; mean age 5.2 ± 1.96 years; range: 2-10 years; initial MI <50%) with bilateral spastic cerebral palsy over a time period of 2 years. All received injections of BoNT/A (Dysport) every 12 weeks with a dose of 30 Units per kilogram body weight into adductor and medial hamstring muscles on both sides. The MI was calculated before treatment and after 1 and 2 years. The mean MI increased from 25.5% (range: 0-48) to 26.7% (+1.2%, range: 0-79) on the right side and from 28.0% (range: 0-40) to 30.6% (+2.6%, range: 3-84) on the left side over 2 years, respectively. Hips of one patient dislocated bilaterally. The mean MI remained stable over 2 years. Although a specific BoNT/A effect cannot be proven because of the open design of this study, we provide strong evidence that the MI can be kept stable for a time period of 2 years under non-surgical management including therapy with BoNT/A even in CP patients with a high risk for hip dislocation. © Georg Thieme Verlag KG Stuttgart · New York.

Thirteen-year outcomes in the Anatomique Benoist Girard II hip prosthesis.

PubMed

Catanach, Michael J M; Sorial, Rami M; Eslick, Guy D

2015-04-01

The Stryker Anatomique Benoist Girard (ABG) hip implant system was a commonly used cementless prosthesis in the early 2000s, which fell from favour after several studies emerged implicating the prosthesis in high rates of revision. This retrospective, single-surgeon clinical study examines the fracture rate, revision rate and reasons for revision in 500 consecutive ABG II primary total conventional hip replacements. Follow-up was conducted by audit of patient notes, patient mailout survey, patient phone contact and audit of the Australian National Joint Replacement Registry (NJRR) database to find instances of fracture and revision. End points were periprosthetic fracture and revision for any reason. Follow-up was 1.2-13.8 years with a mean of 6.58 years. Of the 500 hips, 17 (3.4%) had undergone a revision. Of these, 13 were due to periprosthetic fracture. Four further fractures occurred that were not revised. Eight of these periprosthetic fractures occurred within 1 year post-operatively. There were four revisions for recurrent dislocations. Kaplan-Meier survival curve demonstrates a 93.7% survivorship at 6.58 years for revision for any reason. Multivariate analysis showed the only statistically significant factor for increased risk of revision was smaller stem size. Our results were consistent with the literature in that the ABG II system has good medium-term results but is prone to periprosthetic fractures, especially in the early post-operative period. When used as a primary total hip arthroplasty, the ABG II system has an 8-year revision rate of 5.6% compared with the 4.9% of all primary total hip arthroplasties. © 2014 Royal Australasian College of Surgeons.

Creep of quartz by dislocation and grain boundary processes

NASA Astrophysics Data System (ADS)

Fukuda, J. I.; Holyoke, C. W., III; Kronenberg, A. K.

2015-12-01

Wet polycrystalline quartz aggregates deformed at temperatures T of 600°-900°C and strain rates of 10-4-10-6 s-1 at a confining pressure Pc of 1.5 GPa exhibit plasticity at low T, governed by dislocation glide and limited recovery, and grain size-sensitive creep at high T, governed by diffusion and sliding at grain boundaries. Quartz aggregates were HIP-synthesized, subjecting natural milky quartz powder to T=900°C and Pc=1.5 GPa, and grain sizes (2 to 25 mm) were varied by annealing at these conditions for up to 10 days. Infrared absorption spectra exhibit a broad OH band at 3400 cm-1 due to molecular water inclusions with a calculated OH content (~4000 ppm, H/106Si) that is unchanged by deformation. Rate-stepping experiments reveal different stress-strain rate functions at different temperatures and grain sizes, which correspond to differing stress-temperature sensitivities. At 600-700°C and grain sizes of 5-10 mm, flow law parameters compare favorably with those for basal plasticity and dislocation creep of wet quartzites (effective stress exponents n of 3 to 6 and activation enthalpy H* ~150 kJ/mol). Deformed samples show undulatory extinction, limited recrystallization, and c-axis maxima parallel to the shortening direction. Similarly fine-grained samples deformed at 800°-900°C exhibit flow parameters n=1.3-2.0 and H*=135-200 kJ/mol corresponding to grain size-sensitive Newtonian creep. Deformed samples show some undulatory extinction and grain sizes change by recrystallization; however, grain boundary deformation processes are indicated by the low value of n. Our experimental results for grain size-sensitive creep can be compared with models of grain boundary diffusion and grain boundary sliding using measured rates of silicon grain boundary diffusion. While many quartz mylonites show microstructural and textural evidence for dislocation creep, results for grain size-sensitive creep may apply to very fine-grained (<10 mm) quartz mylonites.

[Bone surgery for unstable hips in patients with cerebral palsy].

PubMed

Poul, J; Pesl, M; Pokorná, M

2004-01-01

The aim of this retrospective study was to compare the efficacy of femoral osteotomy alone with that of osteotomy combined with an acetabular procedure in patients with unstable hips due to spastic cerebral palsy. Sixty-one hip joints in 50 patients who had shown distinct subluxation or dislocation of the joint were operated on. Eleven patients underwent bilateral surgery. Before bone surgery, soft-tissue release involving both the flexors and adductors was performed on 19 hips. Femoral osteotomy alone was performed on 29 hip joints and combined femoral and pelvic osteotomy was carried out on 32 joints.Twelve resections of the proximal femur in seven patients were evaluated as a separate group. All treated hip joints were assessed by clinical and radiographic examination at a follow-up of more than 5 years. The skiagraphs taken in a strictly neutral position of the lower limbs before surgery and at the final examination were evaluated on the basis of Reimers's migration index and Wiberg's centre-edge angle. The locomotor abilities of each child were categorized according to the Vojta scoring system for locomotor development. The range of motion in the treated hip joint was assessed using the standard S. F. T. R. method. The results obtained were statistically analyzed by the Kruskal- Wallis, one-way ANOVA test. A comparison of the results of femoral osteotomy alone with those of combined femoral and pelvic osteotomy showed that the post-operative values of the migration index and centre-edge angle, as compared with the pre-operative ones, were statistically higher (p<0.05) in the latter. In a long-term perspective, the surgery had no adverse effects on a natural development of locomotor abilities of the child. The children had higher scores by the modified Vojta rating system. There was no change in the range of motion in the treated hip joints after the operation. In 28, out of the 32 joints treated by combined femoral and pelvic osteotomy, Salter osteotomy was

Complications Are Not Increased With Acetabular Revision of Metal-on-metal Total Hip Arthroplasty.

PubMed

Penrose, Colin T; Seyler, Thorsten M; Wellman, Samuel S; Bolognesi, Michael P; Lachiewicz, Paul F

2016-10-01

Isolated revision of the acetabular component in the setting of total hip arthroplasty has an increased risk of dislocation. With local soft tissue destruction frequently associated with failed metal-on-metal (MoM) bearings, it is presumed that acetabular revision of these hips will have even greater risk of complications. However, no study directly compares the complications of MoM with metal-on-polyethylene (MoP) acetabular revisions. In the context of a large database analysis, we asked the following questions: (1) Are there differences in early medical or wound complications after isolated acetabular revision of MoM and MoP bearing surfaces? (2) Are there differences in the frequency of dislocation, deep infection, and rerevision based on the bearing surface of the original implant? A review of the 100% Medicare database from 2005 to 2012 was performed using International Classification of Diseases, 9th Revision and Current Procedural Terminology codes. We identified 451 patients with a MoM bearing and 628 patients with a MoP bearing who had an isolated acetabular revision and a minimum followup of 2 years. The incidence, odds ratios, and 95% confidence intervals for early medical or wound complications were calculated using a univariate analysis at 30 days with patient sex and age group-adjusted analysis for blood transfusion. The incidence, odds ratio, and 95% confidence intervals for dislocation, deep infection, and rerevision were calculated using a univariate analysis at 30 day, 90 days, 1 year, and 2 years using a subgroup analysis with the Cochran-Mantel-Haenszel test to adjust for patient gender and age groups. There were no differences between the MoM and MoP isolated acetabular revisions in the incidence of 30-day local complications. There was a greater risk of transfusion in the MoP group than the MoM group (134 of 451 [30%] versus 230 of 628 [37%]; odds ratio [OR], 0.731; 95% confidence interval [CI], 0.565-0.948; p = 0.018). There were no

Dislocation dynamics in hexagonal close-packed crystals

DOE PAGES

Aubry, S.; Rhee, M.; Hommes, G.; ...

2016-04-14

Extensions of the dislocation dynamics methodology necessary to enable accurate simulations of crystal plasticity in hexagonal close-packed (HCP) metals are presented. They concern the introduction of dislocation motion in HCP crystals through linear and non-linear mobility laws, as well as the treatment of composite dislocation physics. Formation, stability and dissociation of and other dislocations with large Burgers vectors defined as composite dislocations are examined and a new topological operation is proposed to enable their dissociation. Furthermore, the results of our simulations suggest that composite dislocations are omnipresent and may play important roles both in specific dislocation mechanisms and in bulkmore » crystal plasticity in HCP materials. While fully microscopic, our bulk DD simulations provide wealth of data that can be used to develop and parameterize constitutive models of crystal plasticity at the mesoscale.« less

Comparison of dislocation density tensor fields derived from discrete dislocation dynamics and crystal plasticity simulations of torsion

DOE PAGES

Jones, Reese E.; Zimmerman, Jonathan A.; Po, Giacomo; ...

2016-02-01

Accurate simulation of the plastic deformation of ductile metals is important to the design of structures and components to performance and failure criteria. Many techniques exist that address the length scales relevant to deformation processes, including dislocation dynamics (DD), which models the interaction and evolution of discrete dislocation line segments, and crystal plasticity (CP), which incorporates the crystalline nature and restricted motion of dislocations into a higher scale continuous field framework. While these two methods are conceptually related, there have been only nominal efforts focused at the global material response that use DD-generated information to enhance the fidelity of CPmore » models. To ascertain to what degree the predictions of CP are consistent with those of DD, we compare their global and microstructural response in a number of deformation modes. After using nominally homogeneous compression and shear deformation dislocation dynamics simulations to calibrate crystal plasticity ow rule parameters, we compare not only the system-level stress-strain response of prismatic wires in torsion but also the resulting geometrically necessary dislocation density fields. To establish a connection between explicit description of dislocations and the continuum assumed with crystal plasticity simulations we ascertain the minimum length-scale at which meaningful dislocation density fields appear. Furthermore, our results show that, for the case of torsion, that the two material models can produce comparable spatial dislocation density distributions.« less

Revision of cemented hip arthroplasty using a hydroxyapatite-ceramic-coated femoral component.

PubMed

Raman, R; Kamath, R P; Parikh, A; Angus, P D

2005-08-01

We report the clinical and radiological outcome of 86 revisions of cemented hip arthroplasties using JRI-Furlong hydroxyapatite-ceramic-coated acetabular and femoral components. The acetabular component was revised in 62 hips and the femoral component in all hips. The mean follow-up was 12.6 years and no patient was lost to follow-up. The mean age of the patients was 71.2 years. The mean Harris hip and Oxford scores were 82 (59 to 96) and 23.4 (14 to 40), respectively. The mean Charnley modification of the Merle d'Aubigné and Postel score was 5 (3 to 6) for pain, 4.9 (3 to 6) for movement and 4.4 (3 to 6) for mobility. Migration of the acetabular component was seen in two hips and the mean acetabular inclination was 42.6 degrees. The mean linear polyethylene wear was 0.05 mm/year. The mean subsidence of the femoral component was 1.9 mm and stress shielding was seen in 23 (28%) with bony ingrowth in 76 (94%). Heterotopic ossification was seen in 12 hips (15%). There were three re-revisions, two for deep sepsis and one for recurrent dislocation and there were no re-revisions for aseptic loosening. The mean EuroQol EQ-5D description scores and health thermometer scores were 0.69 (0.51 to 0.89) and 79 (54 to 95), respectively. With an end-point of definite or probable loosening, the probability of survival at 12 years was 93.9% and 95.6% for the acetabular and femoral components, respectively. Overall survival at 12 years, with removal or further revision of either component for any reason as the end-point, was 92.3%. Our study supports the continued use of this arthroplasty and documents the durability of hydroxyapatite-ceramic-coated components.

Ultrasonic influence on evolution of disordered dislocation structures

NASA Astrophysics Data System (ADS)

Bachurin, D. V.; Murzaev, R. T.; Nazarov, A. A.

2017-12-01

Evolution of disordered dislocation structures under ultrasonic influence is studied in a model two-dimensional grain within the discrete-dislocation approach. Non-equilibrium grain boundary state is mimicked by a mesodefect located at the corners of the grain, stress field of which is described by that of a wedge junction disclination quadrupole. Significant rearrangement related to gliding of lattice dislocations towards the grain boundaries is found, which results in a noticeable reduction of internal stress fields and cancel of disclination quadrupole. The process of dislocation structure evolution passes through two stages: rapid and slow. The main dislocation rearrangement occurs during the first stage. Reduction of internal stress fields is associated with the number of dislocations entered into the grain boundaries. The change of misorientation angle due to lattice dislocations absorbed by the grain boundaries is evaluated. Amplitude of ultrasonic treatment significantly influences the relaxation of dislocation structure. Preliminary elastic relaxation of dislocation structure does not affect substantially the results of the following ultrasonic treatment. Substantial grain size dependence of relaxation of disordered dislocation systems is found. Simulation results are consistent with experimental data.

Neglected locked vertical patellar dislocation

PubMed Central

Gupta, Rakesh Kumar; Gupta, Vinay; Sangwan, Sukhbir Singh; Kamboj, Pradeep

2012-01-01

Patellar dislocations occurring about the vertical and horizontal axis are rare and irreducible. The neglected patellar dislocation is still rarer. We describe the clinical presentation and management of a case of neglected vertical patellar dislocation in a 6 year-old boy who sustained an external rotational strain with a laterally directed force to his knee. Initially the diagnosis was missed and 2 months later open reduction was done. The increased tension generated by the rotation of the lateral extensor retinaculum kept the patella locked in the lateral gutter even with the knee in full extension. Traumatic patellar dislocation with rotation around a vertical axis has been described earlier, but no such neglected case has been reported to the best of our knowledge. PMID:23162154

Thermodynamic dislocation theory: Bauschinger effect

NASA Astrophysics Data System (ADS)

Le, K. C.; Tran, T. M.

2018-04-01

The thermodynamic dislocation theory developed for nonuniform plastic deformations is used here to simulate the stress-strain curves for crystals subjected to antiplane shear-controlled load reversal. We show that the presence of the positive back stress during the load reversal reduces the magnitude of shear stress required to pull excess dislocations back to the center of the specimen. There, the excess dislocations of opposite signs meet and annihilate each other leading to the Bauschinger effect.

The use of a tripolar articulation in revision total hip arthroplasty: a minimum of 24 months' follow-up.

PubMed

Levine, Brett R; Della Valle, Craig J; Deirmengian, Carl A; Breien, Kristoffer M; Weeden, Steven H; Sporer, Scott M; Paprosky, Wayne G

2008-12-01

A retrospective cohort study of 31 hips revised with a tripolar articular construct was performed. Patient demographics and preoperative and postoperative information were recorded. Indications for a tripolar construct were recurrent dislocation and the inability to attain intraoperative stability during hip revision. Nine patients (29%) were revised to the tripolar construct after failure of a constrained liner. Twenty patients (65%) had at least one episode of instability before the most recent revision. At a mean follow-up of 38 months, modified Postel scores improved from a mean of 5.28 to 9.64 (P < .01). Radiographic follow-up revealed no evidence of component loosening/migration, osteolysis, or polyethylene wear. Two patients (7%) required further revision surgery for recurrent instability. A tripolar construct was effective in eliminating or preventing instability in 93% of the complex cases treated. These early results support the use of a tripolar construct in treating recurrent instability or instability encountered at the time of revision hip arthroplasty.

Posterosuperior Placement of a Standard-Sized Cup at the True Acetabulum in Acetabular Reconstruction of Developmental Dysplasia of the Hip With High Dislocation.

PubMed

Xu, Jiawei; Xu, Chen; Mao, Yuanqing; Zhang, Jincheng; Li, Huiwu; Zhu, Zhenan

2016-06-01

We sought to evaluate posterosuperior placement of the acetabular component at the true acetabulum during acetabular reconstruction in patients with Crowe type-IV developmental dysplasia of the hip. Using pelvic computed tomography and image processing, we developed a two-dimensional mapping technique to demonstrate the distribution of preoperative three-dimensional cup coverage at the true acetabulum, determined the postoperative location of the acetabular cup, and calculated postoperative three-dimensional coverage for 16 Crowe type-IV dysplastic hips in 14 patients with a mean age of 52 years (33-78 years) who underwent total hip arthroplasty. Mean follow-up was 6.3 years (5.5-7.3 years). On preoperative mapping, the maximum three-dimensional coverage using a 44-mm cup was 87.31% (77.36%-98.14%). Mapping enabled the successful replacement of 16 hips using a mean cup size of 44.13 mm (42-46 mm) with posterosuperior placement of the cup. Early weight-bearing and no prosthesis revision or loosening during follow-up were achieved in all patients. The postoperative two-dimensional coverage on anteroposterior radiographs and three-dimensional coverage were 96.15% (89.49%-100%) and 83.42% (71.81%-98.50%), respectively. This technique may improve long-term implant survival in patients with Crowe-IV developmental dysplasia of the hip undergoing total hip arthroplasty by allowing the use of durable bearings, increasing host bone coverage, ensuring initial stability, and restoring the normal hip center. Copyright © 2015 Elsevier Inc. All rights reserved.

Do Complication Rates Differ by Gender After Metal-on-metal Hip Resurfacing Arthroplasty? A Systematic Review.

PubMed

Haughom, Bryan D; Erickson, Brandon J; Hellman, Michael D; Jacobs, Joshua J

2015-08-01

Although metal-on-metal (MoM) bearing surfaces provide low rates of volumetric wear and increased stability, evidence suggests that certain MoM hip arthroplasties have high rates of complication and failure. Some evidence indicates that women have higher rates of failure compared with men; however, the orthopaedic literature as a whole has poorly reported such complications stratified by gender. This systematic review aimed to: (1) compare the rate of adverse local tissue reaction (ALTR); (2) dislocation; (3) aseptic loosening; and (4) revision between men and women undergoing primary MoM hip resurfacing arthroplasty (HRA). Systematic MEDLINE and EMBASE searches identified all level I to III articles published in peer-reviewed journals, reporting on the outcomes of interest, for MoM HRA. Articles were limited to those with 2-year followup that reported outcomes by gender. Ten articles met inclusion criteria. Study quality was evaluated using the Modified Coleman Methodology Score; the overall quality was poor. Heterogeneity and bias were analyzed using a Mantel-Haenszel statistical method. Women demonstrated an increased odds of developing ALTR (odds ratio [OR], 5.70 [2.71-11.98]; p<0.001), dislocation (OR, 3.04 [1.2-7.5], p=0.02), aseptic loosening (OR, 3.18 [2.21-4.58], p<0.001), and revision (OR, 2.50 [2.25-2.78], p<0.001) after primary MoM HRA. A systematic review of the currently available literature reveals a higher rate of complications (ALTR, dislocation, aseptic loosening, and revision) after MoM HRA in women compared with men. Although femoral head size has been frequently implicated as a prime factor in the higher rate of complication in women, further research is necessary to specifically probe this relationship. Retrospective studies of data available (eg, registry data) should be undertaken, and moving forward studies should report outcomes by gender (particularly complications). Level III, therapeutic study.

Efficacy of Kirschner-wires and tension band in hip arthroplasty for aged patients with unstable intertrochanteric osteoporotic fracture

PubMed Central

Zhang, Hua; Xu, Zhongwei; Zhou, Aiguo; Yan, Wenlong; Zhao, Pei; Huang, Xiao; Zhang, Jian

2017-01-01

Abstract The aim of this study was to evaluate the efficacy of supplementary fixation in hip arthroplasty with the use of Kirschner-wires and tension band for geriatric patients suffering unstable intertrochanteric osteoporotic fractures. A total of 103 patients aged more than 75 years were recruited. A bipolar or total hip replacement was performed with additional application of Kirschner-wires and tension band, and the participants were followed up for 2 to 11 years. Physical component summary (PCS), mental component summary (MCS), visual analog scale (VAS), and Harris hip score were utilized to evaluate patients’ hip pain and function, as well as the mental condition postoperatively after 1.5 months, 3 months, 6 months, 1 year, and annually thereafter until the latest follow-up in 2015. Patients showed a significant improvement in all scores between 1.5 months and 1 year (P < 0.001), with the good efficacy lasting at least until the 2-year follow-up. None of the patients showed dislocation, implant loosening, or nonunion of the fracture throughout the follow-up period. In conclusion, it was beneficial to treat unstable intertrochanteric osteoporotic fractures in aged patients with hip arthroplasty coupled with Kirschner-wires and tension band. PMID:28072698

Internal stresses, dislocation mobility and ductility

NASA Astrophysics Data System (ADS)

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.

Understanding dislocation mechanics at the mesoscale using phase field dislocation dynamics

PubMed Central

Hunter, A.

2016-01-01

In this paper, we discuss the formulation, recent developments and findings obtained from a mesoscale mechanics technique called phase field dislocation dynamics (PFDD). We begin by presenting recent advancements made in modelling face-centred cubic materials, such as integration with atomic-scale simulations to account for partial dislocations. We discuss calculations that help in understanding grain size effects on transitions from full to partial dislocation-mediated slip behaviour and deformation twinning. Finally, we present recent extensions of the PFDD framework to alternative crystal structures, such as body-centred cubic metals, and two-phase materials, including free surfaces, voids and bi-metallic crystals. With several examples we demonstrate that the PFDD model is a powerful and versatile method that can bridge the length and time scales between atomistic and continuum-scale methods, providing a much needed understanding of deformation mechanisms in the mesoscale regime. PMID:27002063

Tuberculosis of the hip in children: A retrospective analysis of 27 patients.

PubMed

Agarwal, Anil; Suri, Tarun; Verma, Indereshwar; Kumar, Shashi Kant; Gupta, Neeraj; Shaharyar, Abbas

2014-09-01

We retrospectively evaluated the pretreatment radiological presentation and the clinicoradiological outcome at the completion of 1 year chemotherapy in osteoarticular tuberculosis of hip in children to prognosticate correlation between them. We retrospectively analyzed the clinical and plain radiographic findings in 27 patients with an age of 12 years or younger in whom hip tuberculosis was diagnosed and treated between 2006 and 2010. The diagnosis was based on histopathology in 14 and clinicoradiological basis in 13 patients. The pre and post treatment plain radiographs were evaluated according to Shanmugasundaram radiological classification and our observations regarding unclassified cases which were not fit in this classification were suggested. The functional outcome at the completion of chemotherapy was assessed using modified Moon's criteria. The male female ratio was 11:16. The left hip was involved more frequently than the right (17:10). The average age was 7.37 years (range, 2-12 years). In the pretreatment radiographs, 9 hips were normal, 6 traveling, 4 dislocating, 1 protrusio acetabuli, 3 atrophic and 4 unclassified types (3 triradiate; 1 pseudarthrosis coxae). There were no Perthes and mortar pestle at the initial presentation. Posttreatment, the types changed to 9 normal, 3 Perthes, 1 protrusio acetabuli, 1 atrophic, 4 mortar pestle and 9 unclassified types (3 triradiate, 3 pseudarthrosis coxae and 3 ankylosed). There were 37% excellent, 18.5% good, 26% fair and 18.5% poor results. The prognosis was best with initial "triradiate" and normal types and worst with posttreatment atrophic and "ankylosed" types. The Shanmugasundaram radiological types accurately predict prognosis only in normal types and "triradiate" pattern. The functional outcome is independent of radiological morphology of the hip in smaller children.

Atomistic calculations of dislocation core energy in aluminium

DOE PAGES

Zhou, X. W.; Sills, R. B.; Ward, D. K.; ...

2017-02-16

A robust molecular dynamics simulation method for calculating dislocation core energies has been developed. This method has unique advantages: it does not require artificial boundary conditions, is applicable for mixed dislocations, and can yield highly converged results regardless of the atomistic system size. Utilizing a high-fidelity bond order potential, we have applied this method in aluminium to calculate the dislocation core energy as a function of the angle β between the dislocation line and Burgers vector. These calculations show that, for the face-centred-cubic aluminium explored, the dislocation core energy follows the same functional dependence on β as the dislocation elasticmore » energy: Ec = A·sin 2β + B·cos 2β, and this dependence is independent of temperature between 100 and 300 K. By further analysing the energetics of an extended dislocation core, we elucidate the relationship between the core energy and radius of a perfect versus extended dislocation. With our methodology, the dislocation core energy can be accurately accounted for in models of plastic deformation.« less

Atomistic calculations of dislocation core energy in aluminium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, X. W.; Sills, R. B.; Ward, D. K.

A robust molecular dynamics simulation method for calculating dislocation core energies has been developed. This method has unique advantages: it does not require artificial boundary conditions, is applicable for mixed dislocations, and can yield highly converged results regardless of the atomistic system size. Utilizing a high-fidelity bond order potential, we have applied this method in aluminium to calculate the dislocation core energy as a function of the angle β between the dislocation line and Burgers vector. These calculations show that, for the face-centred-cubic aluminium explored, the dislocation core energy follows the same functional dependence on β as the dislocation elasticmore » energy: Ec = A·sin 2β + B·cos 2β, and this dependence is independent of temperature between 100 and 300 K. By further analysing the energetics of an extended dislocation core, we elucidate the relationship between the core energy and radius of a perfect versus extended dislocation. With our methodology, the dislocation core energy can be accurately accounted for in models of plastic deformation.« less

There Is a Significant Discrepancy Between "Big Data" Database and Original Research Publications on Hip Arthroscopy Outcomes: A Systematic Review.

PubMed

Sochacki, Kyle R; Jack, Robert A; Safran, Marc R; Nho, Shane J; Harris, Joshua D

2018-06-01

The purpose of this study was to compare (1) major complication, (2) revision, and (3) conversion to arthroplasty rates following hip arthroscopy between database studies and original research peer-reviewed publications. A systematic review was performed using PRISMA guidelines. PubMed, SCOPUS, SportDiscus, and Cochrane Central Register of Controlled Trials were searched for studies that investigated major complication (dislocation, femoral neck fracture, avascular necrosis, fluid extravasation, septic arthritis, death), revision, and hip arthroplasty conversion rates following hip arthroscopy. Major complication, revision, and conversion to hip arthroplasty rates were compared between original research (single- or multicenter therapeutic studies) and database (insurance database using ICD-9/10 and/or current procedural terminology coding terminology) publishing studies. Two hundred seven studies (201 original research publications [15,780 subjects; 54% female] and 6 database studies [20,825 subjects; 60% female]) were analyzed (mean age, 38.2 ± 11.6 years old; mean follow-up, 2.7 ± 2.9 years). The database studies had a significantly higher age (40.6 + 2.8 vs 35.4 ± 11.6), body mass index (27.4 ± 5.6 vs 24.9 ± 3.1), percentage of females (60.1% vs 53.8%), and longer follow-up (3.1 ± 1.6 vs 2.7 ± 3.0) compared with original research (P < .0001 for all). Ninety-seven (0.6%) major complications occurred in the individual studies, and 95 (0.8%) major complications occurred in the database studies (P = .029; relative risk [RR], 1.3). There was a significantly higher rate of femoral neck fracture (0.24% vs 0.03%; P < .0001; RR, 8.0), and hip dislocation (0.17% vs 0.06%; P = .023; RR, 2.2) in the database studies. Reoperations occurred at a significantly higher rate in the database studies (11.1% vs 7.3%; P < .001; RR, 1.5). There was a significantly higher rate of conversion to arthroplasty in the database studies (8.0% vs 3.7%; P < .001; RR, 2.2). Database

Period-doubling reconstructions of semiconductor partial dislocations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Ji -Sang; Huang, Bing; Wei, Su -Huai

2015-09-18

Atomic-scale understanding and control of dislocation cores is of great technological importance, because they act as recombination centers for charge carriers in optoelectronic devices. Using hybrid density-functional calculations, we present period-doubling reconstructions of a 90 degrees partial dislocation in GaAs, for which the periodicity of like-atom dimers along the dislocation line varies from one to two, to four dimers. The electronic properties of a dislocation change drastically with each period doubling. The dimers in the single-period dislocation are able to interact, to form a dispersive one-dimensional band with deep-gap states. However, the inter-dimer interaction for the double-period dislocation becomes significantlymore » reduced; hence, it is free of mid-gap states. The Ga core undergoes a further period-doubling transition to a quadruple-period reconstruction induced by the formation of small hole polarons. In conclusion, the competition between these dislocation phases suggests a new passivation strategy via population manipulation of the detrimental single-period phase.« less

Ultrasonic Study of Dislocation Dynamics in Lithium -

NASA Astrophysics Data System (ADS)

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.

Elasticity and dislocation anelasticity of crystals

NASA Astrophysics Data System (ADS)

Nikanorov, S. P.; Kardashev, B. K.

The book is concerned with the application of the results of physical acoustic studies of elasticity and dislocation anelasticity to the investigation of interatomic interactions and interactions between lattice defects. The analysis of the potential functions determining the energy of interatomic interactions is based on a study of the elastic properties of crystals over a wide temperature range; data on the dislocation structure and on the interaction between dislocations and point defects are based mainly on a study of inelastic effects. Particular attention is given to the relationship between microplastic effects and the initial stage of plastic deformation under conditions of elastic oscillations, when the multiplication of dislocations is negligible.

Modal analysis of dislocation vibration and reaction attempt frequency

DOE PAGES

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

2017-02-04

Transition state theory is a fundamental approach for temporal coarse-graining. It estimates the reaction rate for a transition processes by quantifying the activation free energy and attempt frequency for the unit process. To calculate the transition rate of a gliding dislocation, the attempt frequency is often obtained from line tension estimates of dislocation vibrations, a highly simplified model of dislocation behavior. This work revisits the calculation of attempt frequency for a dislocation bypassing an obstacle, in this case a self-interstitial atom (SIA) loop. First, a direct calculation of the vibrational characteristics of a finite pinned dislocation segment is compared tomore » line tension estimates before moving to the more complex case of dislocation-obstacle bypass. The entropic factor associated with the attempt frequency is calculated for a finite dislocation segment and for an infinite glide dislocation interacting with an SIA loop. Lastly, it is found to be dislocation length independent for three cases of dislocation-self interstitial atom (SIA) loop interactions.« less

High-impact sport after hip resurfacing: The Ironman triathlon.

PubMed

Girard, J; Lons, A; Pommepuy, T; Isida, R; Benad, K; Putman, S

2017-09-01

Returning to high-impact sport is an increasingly frequent functional demand following hip replacement. The literature, however, is sparse on the subject and nonexistent regarding triathlon. We therefore conducted a retrospective study of hip resurfacing in triathlon players, to determine: (1) whether it is possible to return to this kind of sport; (2) if so, whether it is possible to return to the same level; and (3) how a resurfaced hip behaves under these conditions. Hip resurfacing allows return to competition level in long-distance triathlon. A single-center single-operator retrospective study included patients undergoing hip resurfacing with the Conserve Plus implant inserted through a posterolateral approach, who had ceased long-distance triathlon practice due to osteoarthritis of the hip. Fifty-one of the 1688 patients undergoing resurfacing during the inclusion period were long-distance triathlon players. The series comprised 48 patients: 51 implants; 43 male, 5 female; mean age, 44.8 years (range, 28.2-58.9 years). At a mean 4.7 years' follow-up (range, 2.2-7.6 years), all clinical scores showed significant improvement; Merle d'Aubigné and Harris scores rose respectively from 12.3 (5-16) and 42 (37-56) preoperatively to 17.5 (13-18) and 93.2 (73-100) (P<0.001). There were no cases of dislocation or implant revision. Forty-five patients returned to sport (94%). Rates of return to swimming, cycling and running were respectively 38/48 (79%), 41/48 (85%) and 33/48 (69%). Preoperatively, all patients had taken part in at least 1 competition: 29 with distance=70.3km and 19 with distance=140.6km. At follow-up, 28 patients had taken part in an Ironman competition: 21 with distance=70.3km and 7 with distance=140.6km. Mean competition performance did not differ between pre and postoperative periods. Return-to-sport rates were good following hip resurfacing. Non-impact sports (swimming, cycling) predominated postoperatively, whereas the rate of impact sport

Growth and dislocation studies of β-HMX.

PubMed

Gallagher, Hugh G; Sherwood, John N; Vrcelj, Ranko M

2014-01-01

The defect structure of organic materials is important as it plays a major role in their crystal growth properties. It also can play a subcritical role in "hot-spot" detonation processes of energetics and one such energetic is cyclotetramethylene-tetranitramine, in the commonly used beta form (β-HMX). The as-grown crystals grown by evaporation from acetone show prismatic, tabular and columnar habits, all with {011}, {110}, (010) and (101) faces. Etching on (010) surfaces revealed three different types of etch pits, two of which could be identified with either pure screw or pure edge dislocations, the third is shown to be an artifact of the twinning process that this material undergoes. Examination of the {011} and {110} surfaces show only one type of etch pit on each surface; however their natural asymmetry precludes the easy identification of their Burgers vector or dislocation type. Etching of cleaved {011} surfaces demonstrates that the etch pits can be associated with line dislocations. All dislocations appear randomly on the crystal surfaces and do not form alignments characteristic of mechanical deformation by dislocation slip. Crystals of β-HMX grown from acetone show good morphological agreement with that predicted by modelling, with three distinct crystal habits observed depending upon the supersaturation of the growth solution. Prismatic habit was favoured at low supersaturation, while tabular and columnar crystals were predominant at higher super saturations. The twin plane in β-HMX was identified as a (101) reflection plane. The low plasticity of β-HMX is shown by the lack of etch pit alignments corresponding to mechanically induced dislocation arrays. On untwinned {010} faces, two types of dislocations exist, pure edge dislocations with b = [010] and pure screw dislocations with b = [010]. On twinned (010) faces, a third dislocation type exists and it is proposed that these pits are associated with pure screw dislocations with b = [010

Hip, Hip, Soret!

NASA Astrophysics Data System (ADS)

Müller-Plathe, Florian

Many years ago, Ludwig did detect the behaviour now called the Soret effect. Sodium sulphate in eighteen-fifty-six did not obediently follow Fick's first law. But if he cooled down one side the salt went left, the water to the right. He was surprised in every way. Hip, hip, Soret!

Effects of hydroxyapatite coating of cups used in hip revision arthroplasty

PubMed Central

2012-01-01

Background and purpose Coating of acetabular revision implants with hydroxyapatite (HA) has been proposed to improve ingrowth and stability. We investigated whether HA coating of revision cups can reduce the risk of any subsequent re-revision. Methods We studied uncemented cups either with or without HA coating that were used at a primary acetabular revision and registered in the Swedish Hip Arthroplasty Register (SHAR). 2 such cup designs were identified: Harris-Galante and Trilogy, both available either with or without HA coating. These cups had been used as revision components in 1,780 revisions of total hip arthroplasties (THA) between 1986 and 2009. A Cox proportional hazards model including the type of coating, age at index revision, sex, cause of cup revision, cup design, the use of bone graft at the revision procedure, and the type of cup fixation at primary THA were used to calculate adjusted risk ratios (RRs with 95% CI) for re-revision for any reason or due to aseptic loosening. Results 71% of the cups were coated with HA and 29% were uncoated. At a mean follow-up time of 6.9 (0–24) years, 159 (9%) of all 1,780 cups had been re-revised, mostly due to aseptic loosening (5%), dislocation (2%), or deep infection (1%). HA coating had no significant influence on the risk of re-revision of the cup for any reason (RR = 1.4, CI: 0.9–2.0) or due to aseptic loosening (RR = 1.1, 0.6–1.9). In contrast, HA coating was found to be a risk factor for isolated liner re-revision for any reason (RR = 1.8, CI: 1.01–3.3). Age below 60 years at the index cup revision, dislocation as the cause of the index cup revision, uncemented cup fixation at primary THA, and use of the Harris-Galante cup also increased the risk of re-revision of the cup. In separate analyses in which isolated liner revisions were excluded, bone grafting was found to be a risk factor for re-revision of the metal shell due to aseptic loosening (RR = 2.1, CI: 1.05–4.2). Interpretation We found no

Statistics of dislocation pinning at localized obstacles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dutta, A.; Bhattacharya, M., E-mail: mishreyee@vecc.gov.in; Barat, P.

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 ofmore » 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.« less

Dislocations and other topological oddities

NASA Astrophysics Data System (ADS)

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.

The incidence of avascular necrosis and the radiographic outcome following medial open reduction in children with developmental dysplasia of the hip: a systematic review.

PubMed

Gardner, R O E; Bradley, C S; Howard, A; Narayanan, U G; Wedge, J H; Kelley, S P

2014-02-01

The incidence of clinically significant avascular necrosis (AVN) following medial open reduction of the dislocated hip in children with developmental dysplasia of the hip (DDH) remains unknown. We performed a systematic review of the literature to identify all clinical studies reporting the results of medial open reduction surgery. A total of 14 papers reporting 734 hips met the inclusion criteria. The mean follow-up was 10.9 years (2 to 28). The rate of clinically significant AVN (types 2 to 4) was 20% (149/734). From these papers 221 hips in 174 children had sufficient information to permit more detailed analysis. The rate of AVN increased with the length of follow-up to 24% at skeletal maturity, with type 2 AVN predominating in hips after five years' follow-up. The presence of AVN resulted in a higher incidence of an unsatisfactory outcome at skeletal maturity (55% vs 20% in hips with no AVN; p < 0.001). A higher rate of AVN was identified when surgery was performed in children aged < 12 months, and when hips were immobilised in ≥ 60° of abduction post-operatively. Multivariate analysis showed that younger age at operation, need for further surgery and post-operative hip abduction of ≥ 60° increased the risk of the development of clinically significant AVN.

Effect of Body Mass Index on Complications and Reoperations After Total Hip Arthroplasty.

PubMed

Wagner, Eric R; Kamath, Atul F; Fruth, Kristin M; Harmsen, William S; Berry, Daniel J

2016-02-03

High body mass index (BMI) is associated with increased rates of complications after total hip arthroplasty. Studies to date have evaluated risk mainly as a dichotomous variable according to BMI thresholds. The purpose of this paper was to characterize the risk of complications and implant survival according to BMI as a continuous variable. Using prospectively collected data from our institutional total joint registry, we analyzed 21,361 consecutive hips (17,774 patients) treated with primary total hip arthroplasty between 1985 and 2012 at a single institution. The average BMI at the time of surgery was 28.7 kg/m(2) (range, 15 to 69 kg/m(2)). Estimates of revision surgery and common complications associated with BMI were analyzed using the Kaplan-Meier method of assessing survivorship, with associations of outcomes assessed using a Cox model. Utilizing smoothing spline parameterization, we found that reoperation (p < 0.001) and implant revision or removal rates (p = 0.002) increased with increasing BMI. Increasing BMI was associated with increased rates of early hip dislocation (p = 0.02), wound infection, and, most strikingly, deep periprosthetic infection (a hazard ratio of 1.09 per unit of BMI >25 kg/m(2); p < 0.001). However, we found no association between increasing BMI and any revision for mechanical failure of the implant or between increasing BMI and revision for aseptic implant loosening. There was an inverse correlation between increasing BMI and risk of revision for bearing wear. The rates of reoperation, implant revision or removal, and common complications after total hip arthroplasty were strongly associated with BMI. Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated.

Automated identification and indexing of dislocations in crystal interfaces

DOE PAGES

Stukowski, Alexander; Bulatov, Vasily V.; Arsenlis, Athanasios

2012-10-31

Here, we present a computational method for identifying partial and interfacial dislocations in atomistic models of crystals with defects. Our automated algorithm is based on a discrete Burgers circuit integral over the elastic displacement field and is not limited to specific lattices or dislocation types. Dislocations in grain boundaries and other interfaces are identified by mapping atomic bonds from the dislocated interface to an ideal template configuration of the coherent interface to reveal incompatible displacements induced by dislocations and to determine their Burgers vectors. Additionally, the algorithm generates a continuous line representation of each dislocation segment in the crystal andmore » also identifies dislocation junctions.« less

Worker Dislocation and Its Consequences.

ERIC Educational Resources Information Center

Rosenbaum, Allan; Zirkin, Barbara G.

A study examined the socioeconomic characteristcs, family and social supportive services, economic and social difficulties, education and training levels, and ways in which dislocated workers in Maryland found reemployment. Data were collected from in-depth personal interviews with 9 dislocated workers, questionnaires administered to 45 unemployed…

What Safe Zone? The Vast Majority of Dislocated THAs Are Within the Lewinnek Safe Zone for Acetabular Component Position.

PubMed

Abdel, Matthew P; von Roth, Philipp; Jennings, Matthew T; Hanssen, Arlen D; Pagnano, Mark W

2016-02-01

Numerous factors influence total hip arthroplasty (THA) stability including surgical approach and soft tissue tension, patient compliance, and component position. One long-held tenet regarding component position is that cup inclination and anteversion of 40° ± 10° and 15° ± 10°, respectively, represent a "safe zone" as defined by Lewinnek that minimizes dislocation after primary THA; however, it is clear that components positioned in this zone can and do dislocate. We sought to determine if these classic radiographic targets for cup inclination and anteversion accurately predicted a safe zone limiting dislocation in a contemporary THA practice. From a cohort of 9784 primary THAs performed between 2003 and 2012 at one institution, we retrospectively identified 206 THAs (2%) that subsequently dislocated. Radiographic parameters including inclination, anteversion, center of rotation, and limb length discrepancy were analyzed. Mean followup was 27 months (range, 0-133 months). The majority (58% [120 of 206]) of dislocated THAs had a socket within the Lewinnek safe zone. Mean cup inclination was 44° ± 8° with 84% within the safe zone for inclination. Mean anteversion was 15° ± 9° with 69% within the safe zone for anteversion. Sixty-five percent of dislocated THAs that were performed through a posterior approach had an acetabular component within the combined acetabular safe zones, whereas this was true for only 33% performed through an anterolateral approach. An acetabular component performed through a posterior approach was three times as likely to be within the combined acetabular safe zones (odds ratio [OR], 1.3; 95% confidence interval [CI], 1.1-1.6) than after an anterolateral approach (OR, 0.4; 95% CI, 0.2-0.7; p < 0.0001). In contrast, acetabular components performed through a posterior approach (OR, 1.6; 95% CI, 1.2-1.9) had an increased risk of dislocation compared with those performed through an anterolateral approach (OR, 0.8; 95% CI, 0.7-0.9; p

[Radiographic appraisal between metal and bone interosculate backfill after total hip arthroplasty with trabecular metal cup].

PubMed

Li, Wei; Zhou, Yi-Xin; Wu, Jian; Xu, Hui; Ji, Song-Jie

2009-02-15

To evaluate the bone refilling in the interface between the trabecular metal (TM) acetabular shell and the bone surface according to consecutive X film measuring after surgery. From July 2006 to July 2007, 35 patients (40 hips) accepted total hip replacement using trabecular metal monoblock acetabular cup system (TM). The cup was made of a ellipse shaped press fit Tantalum shell and high cross-linked PE liner (Longevity) with 28 mm inner diameter. The patients demography was: 16 male (20 hips), 19 female (20 hips), 5 bilateral hip replacements, age from 41 - 71 (mean 53), including 18 avascular necrosis hips, 16 osteoarthritis hips (including those secondary to a dysplasia hip), 4 avascular necrosis hips after femoral neck fracture, 2 Ankylosis Spondylitis. All the 40 total hip replacements used posterior approach, using hemispherical acetabular reamer and 2 mm press fit of final metal shell without screw fixation. The consecutive X film was taken at the end time of surgery and 2, 6, 12, 24 weeks, and 12 months. The clinical results was evaluate according to Harris scoring system, and the standard pelvis AP X film was measured at the interface between metal shell and the acetabular bone surface, witch was divided into five regions (A, B, C, D, E). Totally 32 patients (37 hips) were followed with average 8.7 months (7 - 12 months). The Harris before surgery was 50.5 (32 - 85), promoted to 91.0 (72 - 100), including 29 excellent, 6 good, 2 fair, and the total excellent and good rate was 94.6%. Complications include 4 patients leg length discrepancy from 1 - 2 cm, 3 patients moderate thigh pain and released after conservative therapy. No infection and dislocation was found. Twenty-one patients (23 hips) were found lucent line at the bone-metal interface from 1 - 5 mm, most common in B region and BC boundary than C, D, and CD boundary. All the patients followed was found the lucent line disappeared and refilled with bone at X film 24 weeks after surgery, however, no

Rapid rehabilitation and recovery with minimally invasive total hip arthroplasty.

PubMed

Berger, Richard A; Jacobs, Joshua J; Meneghini, R Michael; Della Valle, Craig; Paprosky, Wayne; Rosenberg, Aaron G

2004-12-01

To assess the potential recovery rate of a minimally invasive total hip replacement technique with minimal soft tissue disruption, an accelerated rehabilitation protocol was implemented with weightbearing as tolerated on the day of surgery. One hundred consecutive patients were enrolled in this prospective study. Ninety-seven patients (97%) met all the inpatient physical therapy goals required for discharge to home on the day of surgery; 100% of patients achieved these goals within 23 hours of surgery. Outpatient therapy was initiated in 9% of patients immediately, 62% of patients by 1 week, and all patients by 2 weeks. The mean time to discontinued use of crutches, discontinued use of narcotic pain medications, and resumed driving was 6 days postoperatively. The mean time to return to work was 8 days, discontinued use of any assistive device was 9 days, and resumption of all activities of daily living was 10 days. The mean time to walk (1/2) mile was 16 days. Furthermore, there were no readmissions, no dislocations, and no reoperations. Therefore, a rapid rehabilitation protocol is safe and fulfills the potential benefits of a rapid recovery with minimally invasive total hip arthroplasty.

Cobalt toxicity after revision total hip replacement due to fracture of a ceramic head.

PubMed

Pelayo-de Tomás, J M; Novoa-Parra, C; Gómez-Barbero, P

Symptomatic cobalt toxicity from a failed total hip replacement is a rare, but devastating complication. Potential clinical findings include cardiomyopathy, hypothyroidism, skin rash, visual and hearing impairment, polycythaemia, weakness, fatigue, cognitive impairment, and neuropathy. The case is presented of a 74year-old man in whom, after a ceramic-ceramic replacement and two episodes of prosthetic dislocation, it was decided to replace it with a polyethylene-metal total hip arthroplasty (THA). At 6months after the revision he developed symptoms of cobalt toxicity, confirmed by analytical determination (serum cobalt level=651.2μg/L). After removal of the prosthesis, the levels of chromium and cobalt in blood and urine returned to normal, with the patient currently being asymptomatic. It is recommended to use a new ceramic on ceramic bearing at revision, in order to minimise the risk of wear-related cobalt toxicity following breakage of ceramic components. Copyright © 2016 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

Atomistic simulations of dislocation pileup: Grain boundaries interaction

DOE PAGES

Wang, Jian

2015-05-27

Here, using molecular dynamics (MD) simulations, we studied the dislocation pileup–grain boundary (GB) interactions. Two Σ11 asymmetrical tilt grain boundaries in Al are studied to explore the influence of orientation relationship and interface structure on dislocation activities at grain boundaries. To mimic the reality of a dislocation pileup in a coarse-grained polycrystalline, we optimized the dislocation population in MD simulations and developed a predict-correct method to create a dislocation pileup in MD simulations. MD simulations explored several kinetic processes of dislocations–GB reactions: grain boundary sliding, grain boundary migration, slip transmission, dislocation reflection, reconstruction of grain boundary, and the correlation ofmore » these kinetic processes with the available slip systems across the GB and atomic structures of the GB.« less

Hip joint replacement

MedlinePlus

... Total hip replacement; Hip hemiarthroplasty; Arthritis - hip replacement; Osteoarthritis - hip replacement ... total hip replacement surgery in patients with hip osteoarthritis: a long-term follow-up of a randomised ...

Electron energy can oscillate near a crystal dislocation

DOE PAGES

Li, Mingda; Cui, Wenping; Dresselhaus, Mildred S.; ...

2017-01-25

Crystal dislocations govern the plastic mechanical properties of materials but also affect the electrical and optical properties. However, a fundamental and quantitative quantum field theory of a dislocation has remained undiscovered for decades. Here in this article we present an exactly-solvable one-dimensional quantum field theory of a dislocation, for both edge and screw dislocations in an isotropic medium, by introducing a new quasiparticle which we have called the ‘dislon’. The electron-dislocation relaxation time can then be studied directly from the electron self-energy calculation, which is reducible to classical results. In addition, we predict that the electron energy will experience anmore » oscillation pattern near a dislocation. Compared with the electron density’s Friedel oscillation, such an oscillation is intrinsically different since it exists even with only single electron is present. With our approach, the effect of dislocations on materials’ non-mechanical properties can be studied at a full quantum field theoretical level.« less

Tuberculosis of the hip in children: A retrospective analysis of 27 patients

PubMed Central

Agarwal, Anil; Suri, Tarun; Verma, Indereshwar; Kumar, Shashi Kant; Gupta, Neeraj; Shaharyar, Abbas

2014-01-01

Background: We retrospectively evaluated the pretreatment radiological presentation and the clinicoradiological outcome at the completion of 1 year chemotherapy in osteoarticular tuberculosis of hip in children to prognosticate correlation between them. Materials and Methods: We retrospectively analyzed the clinical and plain radiographic findings in 27 patients with an age of 12 years or younger in whom hip tuberculosis was diagnosed and treated between 2006 and 2010. The diagnosis was based on histopathology in 14 and clinicoradiological basis in 13 patients. The pre and post treatment plain radiographs were evaluated according to Shanmugasundaram radiological classification and our observations regarding unclassified cases which were not fit in this classification were suggested. The functional outcome at the completion of chemotherapy was assessed using modified Moon's criteria. Results: The male female ratio was 11:16. The left hip was involved more frequently than the right (17:10). The average age was 7.37 years (range, 2-12 years). In the pretreatment radiographs, 9 hips were normal, 6 traveling, 4 dislocating, 1 protrusio acetabuli, 3 atrophic and 4 unclassified types (3 triradiate; 1 pseudarthrosis coxae). There were no Perthes and mortar pestle at the initial presentation. Posttreatment, the types changed to 9 normal, 3 Perthes, 1 protrusio acetabuli, 1 atrophic, 4 mortar pestle and 9 unclassified types (3 triradiate, 3 pseudarthrosis coxae and 3 ankylosed). There were 37% excellent, 18.5% good, 26% fair and 18.5% poor results. The prognosis was best with initial “triradiate” and normal types and worst with posttreatment atrophic and “ankylosed” types. Conclusions: The Shanmugasundaram radiological types accurately predict prognosis only in normal types and “triradiate” pattern. The functional outcome is independent of radiological morphology of the hip in smaller children. PMID:25298552

The use of customized cages in revision total hip arthroplasty for Paprosky type III acetabular bone defects.

PubMed

Mao, Yuanqing; Xu, Chen; Xu, Jiawei; Li, Huiwu; Liu, Fengxiang; Yu, Degang; Zhu, Zhenan

2015-10-01

Revision total hip arthroplasty (THA) is challenging if severe periacetabular bone loss is present. Here we describe a method that uses a customised cage to reconstruct an acetabulum with a massive bone defect. Designed with the aid of the rapid prototyping technique, a customised cage with a hook, crest and flange or braids was made, and then utilized to reconstruct severe compromised acetabulum in revision THA since 2001. Twenty-two patients (23 hips) were included in this study. The mean patient age at the time of surgery was 60.9 years (range, 38-80 years). Three hips had massive acetabular bone defects of Paprosky type IIIA and 20 of type IIIB. The Harris hip score was used to evaluate hip function. Radiographs were taken to evaluate loosening of the cage and resorption of allograft bone. The average follow up was 81.6 ± 24.9 months. The mean Harris hip score improved from 39.6 pre-operatively to 80.9 at the final follow-up. There were no instances of deep infection, severe venous thrombosis, and nerve palsy. One patient who had an intra-operative rupture of the superior acetabular artery was successfully treated using the haemostatic suturing technique. Two patients experienced dislocation at post-operative days four and six, respectively, and both were treated with closed reduction and skin traction for three weeks. The present study demonstrates that a customised cage may be a promising option for THA revision of severely compromised acetabula. Extended follow-up is necessary to evaluate the long-term performance of this approach.

Knee Dislocations in Sports Injuries

PubMed Central

Pardiwala, Dinshaw N; Rao, Nandan N; Anand, Karthik; Raut, Alhad

2017-01-01

Knee dislocations are devastating when they occur on the athletic field or secondary to motor sports. The complexity of presentation and spectrum of treatment options makes these injuries unique and extremely challenging to even the most experienced knee surgeons. An astute appreciation of the treatment algorithm is essential to plan individualized management since no two complex knee dislocations are ever the same. Moreover, attention to detail and finesse of surgical technique are required to obtain a good functional result and ensure return to play. Over the past 10 years, our service has treated 43 competitive sportsmen with knee dislocations, and this experience forms the basis for this narrative review. PMID:28966379

Creep Deformation by Dislocation Movement in Waspaloy

PubMed Central

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

2017-01-01

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. PMID:28772421

Te homogeneous precipitation in Ge dislocation loop vicinity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perrin Toinin, J.; Portavoce, A., E-mail: alain.portavoce@im2np.fr; Texier, M.

2016-06-06

High resolution microscopies were used to study the interactions of Te atoms with Ge dislocation loops, after a standard n-type doping process in Ge. Te atoms neither segregate nor precipitate on dislocation loops, but form Te-Ge clusters at the same depth as dislocation loops, in contradiction with usual dopant behavior and thermodynamic expectations. Atomistic kinetic Monte Carlo simulations show that Te atoms are repulsed from dislocation loops due to elastic interactions, promoting homogeneous Te-Ge nucleation between dislocation loops. This phenomenon is enhanced by coulombic interactions between activated Te{sup 2+} or Te{sup 1+} ions.

Dislocated Shoulder

MedlinePlus

... up of three bones: your collarbone, your shoulder blade, and your upper arm bone. The top of ... fits into a cuplike socket in your shoulder blade. A shoulder dislocation is an injury that happens ...

Revision hip preservation surgery with hip arthroscopy: clinical outcomes.

PubMed

Domb, Benjamin G; Stake, Christine E; Lindner, Dror; El-Bitar, Youseff; Jackson, Timothy J

2014-05-01

To analyze and report the clinical outcomes of a cohort of patients who underwent revision hip preservation with arthroscopy and determine predictors of positive and negative outcomes. During the study period from April 2008 to December 2010, all patients who underwent revision hip preservation with arthroscopy were included. This included patients who had previous open surgery and underwent revision with arthroscopy. Patient-reported outcome (PRO) scores were obtained preoperatively and at 3-month, 1-year, 2-year, and 3-year follow-up time points. Any revision surgeries and conversions to total hip arthroplasty were noted. A multiple regression analysis was performed to look for positive and negative predictive factors for improvement in PROs after revision hip arthroscopy. Forty-seven hips in 43 patients had completed 2 years' follow-up or needed total hip arthroplasty. The mean length of follow-up was 29 months (range, 24 to 47 months). Of the hips, 31 (66%) had either unaddressed or incompletely treated femoroacetabular impingement. There was a significant improvement in all PRO scores at a mean of 29 months after revision (P < .0001). The visual analog scale score improved from 7.3 ± 1.5 to 3.9 ± 2.5 (P < .0001). Improvements in the Non-Arthritic Hip Score of at least 10 points and 20 points were found in 28 hips (65%) and 19 hips (44%), respectively. Four hips in 3 patients required conversion to total hip arthroplasty. Positive predictive factors for PRO improvement were previous open surgery, pincer impingement, cam impingement, symptomatic heterotopic ossification, and segmental labral defects treated with labral reconstruction. On the basis of multiple PROs, revision hip preservation with hip arthroscopy can achieve moderately successful outcomes and remains a viable treatment strategy after failed primary hip preservation surgery. Preoperative predictors of success after revision hip arthroscopy include segmental labral defects, unaddressed or

3D discrete dislocation dynamics study of creep behavior in Ni-base single crystal superalloys by a combined dislocation climb and vacancy diffusion model

NASA Astrophysics Data System (ADS)

Gao, Siwen; Fivel, Marc; Ma, Anxin; Hartmaier, Alexander

2017-05-01

A three-dimensional (3D) discrete dislocation dynamics (DDD) creep model is developed to investigate creep behavior under uniaxial tensile stress along the crystallographic [001] direction in Ni-base single crystal superalloys, which takes explicitly account of dislocation glide, climb and vacancy diffusion, but neglects phase transformation like rafting of γ‧ precipitates. The vacancy diffusion model takes internal stresses by dislocations and mismatch strains into account and it is coupled to the dislocation dynamics model in a numerically efficient way. This model is helpful for understanding the fundamental creep mechanisms in superalloys and clarifying the effects of dislocation glide and climb on creep deformation. In cases where the precipitate cutting rarely occurs, e.g. due to the high anti-phase boundary energy and the lack of superdislocations, the dislocation glide in the γ matrix and the dislocation climb along the γ/γ‧ interface dominate plastic deformation. The simulation results show that a high temperature or a high stress both promote dislocation motion and multiplication, so as to cause a large creep strain. Dislocation climb accelerated by high temperature only produces a small plastic strain, but relaxes the hardening caused by the filling γ channels and lets dislocations further glide and multiply. The strongest variation of vacancy concentration occurs in the horizontal channels, where more mixed dislocations exit and tend to climb. The increasing internal stresses due to the increasing dislocation density are easily overcome by dislocations under a high external stress that leads to a long-term dislocation glide accompanied by multiplication.

Clinical and radiological outcomes with the Durom™ acetabular cup for large-diameter total hip arthroplasty: 177 implants after a mean of 80 months.

PubMed

Saragaglia, D; Belvisi, B; Rubens-Duval, B; Pailhé, R; Rouchy, R C; Mader, R

2015-06-01

Large-diameter metal-on-metal hip prostheses are no longer used, but their outcomes after more than 5 years are unknown. We conducted a retrospective study with a 6.8-year mean follow-up to assess clinical outcomes after Durom™ cup implantation, including the dislocation rate, comparatively to the reference metal-on-polyethylene bearing. We determined the rate of failure ascribable to Durom™ cup use. We also looked for a sharp drop in the implant survival curve during the follow-up period and for factors associated with adverse reactions to metal debris (ARMDs). We hypothesised that clinical outcomes after Durom™ cup implantation were similar to those seen with a metal-on-polyethylene bearing, except for a lower rate of dislocation. We included 177 consecutive THA procedures that were performed between 2005 and 2008 in 165 patients with a mean age of 57.6 ± 9.4 years (range, 31-76 years) and involved the implantation of a Durom™ cup, a femoral head greater than 36mm in diameter, and a PF(®) femoral stem (Zimmer, Etupes, France). The mini-posterior approach was used, with 2mm of acetabular overreaming in 82% of cases, a short femoral neck in 75% of cases, and a mean cup inclination of 34 ± 5° (range, 21-50°). Outcomes were assessed for 156 THA procedures in 146 patients after a mean follow-up of 6 years 8 months. The mean Postel-Merle d'Aubigné score improved from 9.7 ± 2.7 (range, 4-14) to 17.4 ± 1.7 (range, 15-18) and the mean Harris hip score from 45.2 ± 15.3 (range, 9-83) to 96.3 ± 7 (75-100). No episodes of dislocation were recorded. We identified 7 failures ascribable to the Durom™ cup including 6 due to ARMD and 1 to aseptic loosening. Implant survival after a mean of 80months was 95.5% (95% CI, 93.1-99.2), with no sharp drop in the survival curve. The Durom™ cup eliminates the risk of hip dislocation and produces similar functional outcomes to those seen with metal-on-polyethylene bearings after a mean follow-up of 80 months

Dislocation nucleation facilitated by atomic segregation

NASA Astrophysics Data System (ADS)

Zou, Lianfeng; Yang, Chaoming; Lei, Yinkai; Zakharov, Dmitri; Wiezorek, Jörg M. K.; Su, Dong; Yin, Qiyue; Li, Jonathan; Liu, Zhenyu; Stach, Eric A.; Yang, Judith C.; Qi, Liang; Wang, Guofeng; Zhou, Guangwen

2018-01-01

Surface segregation--the enrichment of one element at the surface, relative to the bulk--is ubiquitous to multi-component materials. Using the example of a Cu-Au solid solution, we demonstrate that compositional variations induced by surface segregation are accompanied by misfit strain and the formation of dislocations in the subsurface region via a surface diffusion and trapping process. The resulting chemically ordered surface regions acts as an effective barrier that inhibits subsequent dislocation annihilation at free surfaces. Using dynamic, atomic-scale resolution electron microscopy observations and theory modelling, we show that the dislocations are highly active, and we delineate the specific atomic-scale mechanisms associated with their nucleation, glide, climb, and annihilation at elevated temperatures. These observations provide mechanistic detail of how dislocations nucleate and migrate at heterointerfaces in dissimilar-material systems.

BBilateral Neglected Anterior Shoulder Dislocation with Greater Tuberosity Fractures

PubMed Central

Upasani, Tejas; Bhatnagar, Abhinav; Mehta, Sonu

2016-01-01

Introduction: Shoulder dislocations are a very common entity in routine orthopaedic practice. Chronic unreduced anterior dislocations of the shoulder are not very common. Neurological and vascular complications may occur as a result of an acute anterior dislocation of the shoulder or after a while in chronic unreduced shoulder dislocation. Open reduction is indicated for most chronic shoulder dislocations. We report a case of neglected bilateral anterior shoulder dislocation with bilateral displaced greater tuberosity fracture. To the best of our knowledge, only a handful cases have been reported in literature with bilateral anterior shoulder dislocation with bilateral fractures. Delayed diagnosis/reporting is a scenario which makes the list even slimmer and management all the more challenging. Case Report: We report a case of a 35-year-old male who had bilateral anterior shoulder dislocation and bilateral greater tuberosity fracture post seizure and failed to report it for a period of 30 days. One side was managed conservatively with closed reduction and immobilization and the other side with open reduction. No neurovascular complications pre or post reduction of shoulder were seen. Conclusion: Shoulder dislocations should always be suspected post seizures and if found should be treated promptly. Treatment becomes difficult for any shoulder dislocation that goes untreated for considerable period of time PMID:27703939

Unravelling the physics of size-dependent dislocation-mediated plasticity

NASA Astrophysics Data System (ADS)

El-Awady, Jaafar A.

2015-01-01

Size-affected dislocation-mediated plasticity is important in a wide range of materials and technologies. Here we develop a generalized size-dependent dislocation-based model that predicts strength as a function of crystal/grain size and the dislocation density. Three-dimensional (3D) discrete dislocation dynamics (DDD) simulations reveal the existence of a well-defined relationship between strength and dislocation microstructure at all length scales for both single crystals and polycrystalline materials. The results predict a transition from dislocation-source strengthening to forest-dominated strengthening at a size-dependent critical dislocation density. It is also shown that the Hall-Petch relationship can be physically interpreted by coupling with an appropriate kinetic equation of the evolution of the dislocation density in polycrystals. The model is shown to be in remarkable agreement with experiments. This work presents a micro-mechanistic framework to predict and interpret strength size-scale effects, and provides an avenue towards performing multiscale simulations without ad hoc assumptions.

[Characteristics in treatment of the hip in patients with Down syndrome].

PubMed

Peterlein, C-D; Schiel, M; Timmesfeld, N; Schofer, M D; Eberhardt, O; Wirth, T; Fernandez, F F

2013-12-01

preoperative and postoperative range of motion of the hip joint between groups detected capsular insufficiency, increased ligamentous laxity and muscular hypotonia in patients with Down syndrome. Comparison of pelvic radiographs demonstrated significant improvement concerning measured angles in both groups. Preoperative values with respect to AC angle and CE angle were demonstrated to be lower in the hip dysplasia group (p < 0.01); whereas values for ACM angle were comparable between groups. Hypermobility and secondary dislocation of the hip joint is a common problem in patients with Down syndrome, which often requires surgical intervention at an early stage. According to our data and clinical results we suggest a complete redirectional acetabular osteotomy in combination with capsular plication for treatment of this challenging condition. Georg Thieme Verlag KG Stuttgart · New York.

Atlanto-occipital dislocation: Case report and discussion.

PubMed

Asfaw, Tehetena; Chow, Bernard; Frederiksen, Ryan A

2011-01-01

Traumatic atlanto-occipital dislocation is an uncommon injury that frequently results in either a fatal outcome or severe neurologic deficit. This diagnosis must be considered for any patients who may have had cervical spine damage after high trauma, even in the absence of neurologic signs, as there have been reports of cases without neurologic impairment. In addition to radiographic examination, including lateral cervical radiographs, supplemental imaging with CT or MRI may be required to confirm diagnosis in equivocal cases, and to help in evaluation of bone and nervous structures. Moreover, these modalities allow measurement of the magnitude of dislocation and aid in classification of type of dislocation, which helps guide management. A systematic approach to evaluating the cranio-cervical relationship is critical to identifying atlanto-occipital dislocation. This case report presents and discusses imaging findings that will assist in the diagnosis of atlanto-occipital dislocation.

Kneecap dislocation

MedlinePlus

... dislocates to the outside of the knee Knee pain and tenderness Knee swelling "Sloppy" kneecap -- you can move the kneecap ... knee and you notice: Increased instability in your knee Pain or swelling return after they went away Your ...

A Review of Periprosthetic Femoral Fractures Associated With Total Hip Arthroplasty

PubMed Central

Marsland, Daniel; Mears, Simon C.

2012-01-01

Periprosthetic fractures of the femur in association with total hip arthroplasty are increasingly common and often difficult to treat. Patients with periprosthetic fractures are typically elderly and frail and have osteoporosis. No clear consensus exists regarding the optimal management strategy because there is limited high-quality research. The Vancouver classification facilitates treatment decisions. In the presence of a stable prosthesis (type-B1 and -C fractures), most authors recommend surgical stabilization of the fracture with plates, strut grafts, or a combination thereof. In up to 20% of apparent Vancouver type-B1 fractures, the femoral stem is loose, which may explain the high failure rates associated with open reduction and internal fixation. Some authors recommend routine opening and dislocation of the hip to perform an intraoperative stem stability test to rule out a loose component. Advances in plating techniques and technology are improving the outcomes for these fractures. For fractures around a loose femoral prosthesis (types B2 and 3), revision using an extensively porous-coated uncemented long stem, with or without additional fracture fixation, appears to offer the most reliable outcome. Cement-in-cement revision using a long-stem prosthesis is feasible in elderly patients with a well-fixed cement mantle. It is essential to treat the osteoporosis to help fracture healing and to prevent further fractures. We provide an overview of the causes, classification, and management of periprosthetic femoral fractures around a total hip arthroplasty based on the current best available evidence. PMID:23569704

Hydrogenated vacancies lock dislocations in aluminium

PubMed Central

Xie, Degang; Li, Suzhi; Li, Meng; Wang, Zhangjie; Gumbsch, Peter; Sun, Jun; Ma, Evan; Li, Ju; Shan, Zhiwei

2016-01-01

Due to its high diffusivity, hydrogen is often considered a weak inhibitor or even a promoter of dislocation movements in metals and alloys. By quantitative mechanical tests in an environmental transmission electron microscope, here we demonstrate that after exposing aluminium to hydrogen, mobile dislocations can lose mobility, with activating stress more than doubled. On degassing, the locked dislocations can be reactivated under cyclic loading to move in a stick-slip manner. However, relocking the dislocations thereafter requires a surprisingly long waiting time of ∼103 s, much longer than that expected from hydrogen interstitial diffusion. Both the observed slow relocking and strong locking strength can be attributed to superabundant hydrogenated vacancies, verified by our atomistic calculations. Vacancies therefore could be a key plastic flow localization agent as well as damage agent in hydrogen environment. PMID:27808099

Hydrogenated vacancies lock dislocations in aluminium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Degang; Li, Suzhi; Li, Meng

Due to its high diffusivity, hydrogen is often considered a weak inhibitor or even a promoter of dislocation movements in metals and alloys. By quantitative mechanical tests in an environmental transmission electron microscope, here we demonstrate that after exposing aluminium to hydrogen, mobile dislocations can lose mobility, with activating stress more than doubled. On degassing, the locked dislocations can be reactivated under cyclic loading to move in a stick-slip manner. However, relocking the dislocations thereafter requires a surprisingly long waiting time of ~10 3 s, much longer than that expected from hydrogen interstitial diffusion. Both the observed slow relocking andmore » strong locking strength can be attributed to superabundant hydrogenated vacancies, verified by our atomistic calculations. In conclusion, vacancies therefore could be a key plastic flow localization agent as well as damage agent in hydrogen environment.« less

Hydrogenated vacancies lock dislocations in aluminium

DOE PAGES

Xie, Degang; Li, Suzhi; Li, Meng; ...

2016-11-03

Due to its high diffusivity, hydrogen is often considered a weak inhibitor or even a promoter of dislocation movements in metals and alloys. By quantitative mechanical tests in an environmental transmission electron microscope, here we demonstrate that after exposing aluminium to hydrogen, mobile dislocations can lose mobility, with activating stress more than doubled. On degassing, the locked dislocations can be reactivated under cyclic loading to move in a stick-slip manner. However, relocking the dislocations thereafter requires a surprisingly long waiting time of ~10 3 s, much longer than that expected from hydrogen interstitial diffusion. Both the observed slow relocking andmore » strong locking strength can be attributed to superabundant hydrogenated vacancies, verified by our atomistic calculations. In conclusion, vacancies therefore could be a key plastic flow localization agent as well as damage agent in hydrogen environment.« less

Lack of consensus on optimal acetabular cup orientation because of variation in assessment methods in total hip arthroplasty: a systematic review.

PubMed

Snijders, Thom E; Willemsen, Koen; van Gaalen, Steven M; Castelein, Rene M; Weinans, Harrie; de Gast, Arthur

2018-05-01

Dislocation is one of the main reasons for revision of total hip arthroplasty but dislocation rates have not changed in the past decades, compromising patients' well-being. Acetabular cup orientation plays a key role in implant stability and has been widely studied. This article investigates whether there is a consensus on optimal cup orientation, which is necessary when using a navigation system. A systematic search of the literature in the PubMed, Embase and Cochrane databases was performed (March 2017) to identify articles that investigated the direct relationship between cup orientation and dislocation, including a thorough evaluation of postoperative cup orientation assessment methods. Twenty eight relevant articles evaluating a direct relation between dislocation and cup orientation could not come to a consensus. The key reason is a lack of uniformity in the assessment of cup orientation. Cup orientation is assessed with different imaging modalities, different methodologies, different definitions for inclination and anteversion, several reference planes and distinct patient positions. All available studies lack uniformity in cup orientation assessment; therefore it is impossible to reach consensus on optimal cup orientation. Using navigation systems for placement of the cup is inevitably flawed when using different definitions in the preoperative planning, peroperative placement and postoperative evaluation. Further methodological development is required to assess cup orientation. Consequently, the postoperative assessment should be uniform, thus differentiating between anterior and posterior dislocation, use the same definitions for inclination and anteversion with the same reference plane and with the patient in the same position.

Peierls-Nabarro modeling of dislocations in UO2

NASA Astrophysics Data System (ADS)

Skelton, Richard; Walker, Andrew M.

2017-11-01

Under conditions of high stress or low temperature, glide of dislocations plays an important role in the deformation of UO2. In this paper, the Peierls-Nabarro model is used to calculate the core widths and Peierls stresses of ½<110> edge and screw dislocations gliding on {100}, {110}, and {111}. The energy of the inelastic displacement field in the dislocation core is parameterized using generalized stacking fault energies, which are calculated atomistically using interatomic potentials. We use seven different interatomic potential models, representing the variety of different models available for UO2. The different models broadly agree on the relative order of the strengths of the different slip systems, with the 1/2<110>{100} edge dislocation predicted to be the weakest slip system and 1/2<110>{110} the strongest. However, the calculated Peierls stresses depend strongly on the interatomic potential used, with values ranging between 2.7 and 12.9 GPa for glide of 1/2<110>{100} edge dislocations, 16.4-32.3 GPa for 1/2<110>{110} edge dislocations, and 6.8-13.6 GPa for 1/2<110>{111} edge dislocations. The glide of 1/2<110> screw dislocations in UO2 is also found to depend on the interatomic potential used, with some models predicting similar Peierls stresses for glide on {100} and {111}, while others predict a unique easy glide direction. Comparison with previous fully atomistic calculations show that the Peierls-Nabarro model can accurately predict dislocation properties in UO2.

Surface dislocation nucleation controlled deformation of Au nanowires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roos, B.; Kapelle, B.; Volkert, C. A., E-mail: volkert@ump.gwdg.de

2014-11-17

We investigate deformation in high quality Au nanowires under both tension and bending using in-situ transmission electron microscopy. Defect evolution is investigated during: (1) tensile deformation of 〈110〉 oriented, initially defect-free, single crystal nanowires with cross-sectional widths between 30 and 300 nm, (2) bending deformation of the same wires, and (3) tensile deformation of wires containing coherent twin boundaries along their lengths. We observe the formation of twins and stacking faults in the single crystal wires under tension, and storage of full dislocations after bending of single crystal wires and after tension of twinned wires. The stress state dependence of themore » deformation morphology and the formation of stacking faults and twins are not features of bulk Au, where deformation is controlled by dislocation interactions. Instead, we attribute the deformation morphologies to the surface nucleation of either leading or trailing partial dislocations, depending on the Schmid factors, which move through and exit the wires producing stacking faults or full dislocation slip. The presence of obstacles such as neutral planes or twin boundaries hinder the egress of the freshly nucleated dislocations and allow trailing and leading partial dislocations to combine and to be stored as full dislocations in the wires. We infer that the twins and stacking faults often observed in nanoscale Au specimens are not a direct size effect but the result of a size and obstacle dependent transition from dislocation interaction controlled to dislocation nucleation controlled deformation.« less

Isometric hip-rotator torque production at varying degrees of hip flexion.

PubMed

Johnson, Sam; Hoffman, Mark

2010-02-01

Hip torque production is associated with certain knee injuries. The hip rotators change function depending on hip angle. To compare hip-rotator torque production between 3 angles of hip flexion, limbs, and sexes. Descriptive. University sports medicine research laboratory. 15 men and 15 women, 19-39 y. Three 6-s maximal isometric contractions of the hip external and internal rotators at 10 degrees, 40 degrees, and 90 degrees of hip flexion on both legs. Average torque normalized to body mass. Internal-rotation torque was greatest at 90 degrees of hip flexion, followed by 40 degrees of hip flexion and finally 10 degrees of hip flexion. External-rotation torque was not different based on hip flexion. The nondominant leg's external rotators were stronger than the dominant leg's, but the reverse was true for internal rotators. Finally, the men had more overall rotator torque. Hip-rotation torque production varies between flexion angle, leg, and sex. Clinicians treating lower extremity problems need to be aware of these differences.

The results of a proximally-coated cementless femoral component in total hip replacement: a five- to 12-year follow-up.

PubMed

Kim, Y-H

2008-03-01

This study reviewed the results of a cementless anatomical femoral component to give immediate post-operative stability, and with a narrow distal section in order not to contact the femoral cortex in the diaphysis, ensuring exclusively metaphyseal loading. A total of 471 patients (601 hips) who had a total hip replacement between March 1995 and February 2002 were included in the study. There were 297 men and 174 women. The mean age at the time of operation was 52.7 years (28 to 63). Clinical and radiological evaluation were performed at each follow-up. Bone densitometry was carried out on all patients two weeks after operation and at the final follow-up examination. The mean follow-up was 8.8 years (5 to 12). The mean pre-operative Harris hip score was 41 points (16 to 54), which improved to a mean of 96 (68 to 100) at the final follow-up. No patient complained of thigh pain at any stage. No acetabular or femoral osteolysis was observed and no hip required revision for aseptic loosening of either component. Deep infection occurred in two hips (0.3%) which required revision. One hip (0.2%) required revision of the acetabular component for recurrent dislocation. Bone mineral densitometry revealed a minimal bone loss in the proximal femur. This cementless anatomical femoral component with metaphyseal loading but without distal fixation produced satisfactory fixation and encourages proximal femoral loading.

Dynamics of threading dislocations in porous heteroepitaxial GaN films

NASA Astrophysics Data System (ADS)

Gutkin, M. Yu.; Rzhavtsev, E. A.

2017-12-01

Behavior of threading dislocations in porous heteroepitaxial gallium nitride (GaN) films has been studied using computer simulation by the two-dimensional discrete dislocation dynamics approach. A computational scheme, where pores are modeled as cross sections of cylindrical cavities, elastically interacting with unidirectional parallel edge dislocations, which imitate threading dislocations, is used. Time dependences of coordinates and velocities of each dislocation from dislocation ensembles under investigation are obtained. Visualization of current structure of dislocation ensemble is performed in the form of a location map of dislocations at any time. It has been shown that the density of appearing dislocation structures significantly depends on the ratio of area of a pore cross section to area of the simulation region. In particular, increasing the portion of pores surface on the layer surface up to 2% should lead to about a 1.5-times decrease of the final density of threading dislocations, and increase of this portion up to 15% should lead to approximately a 4.5-times decrease of it.

Hydrogen diffusion in the elastic fields of dislocations in iron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sivak, A. B., E-mail: Sivak-AB@nrcki.ru; Sivak, P. A.; Romanov, V. A.

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 ofmore » 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.« less

Degenerative phenotypes caused by the combined deficiency of murine HIP1 and HIP1r are rescued by human HIP1.

PubMed

Bradley, Sarah V; Hyun, Teresa S; Oravecz-Wilson, Katherine I; Li, Lina; Waldorff, Erik I; Ermilov, Alexander N; Goldstein, Steven A; Zhang, Claire X; Drubin, David G; Varela, Kate; Parlow, Al; Dlugosz, Andrzej A; Ross, Theodora S

2007-06-01

The members of the huntingtin-interacting protein-1 (HIP1) family, HIP1 and HIP1-related (HIP1r), are multi-domain proteins that interact with inositol lipids, clathrin and actin. HIP1 is over-expressed in a variety of cancers and both HIP1 and HIP1r prolong the half-life of multiple growth factor receptors. To better understand the physiological importance of the HIP1 family in vivo, we have analyzed a large cohort of double Hip1/Hip1r knockout (DKO) mice. All DKO mice were dwarfed, afflicted with severe vertebral defects and died in early adulthood. These phenotypes were not observed during early adulthood in the single Hip1 or Hip1r knockouts, indicating that HIP1 and HIP1r compensate for one another. Despite the ability of HIP1 and HIP1r to modulate growth factor receptor levels when over-expressed, studies herein using DKO fibroblasts indicate that the HIP1 family is not necessary for endocytosis but is necessary for the maintenance of diverse adult tissues in vivo. To test if human HIP1 can function similar to mouse HIP1, transgenic mice with 'ubiquitous' expression of the human HIP1 cDNA were generated and crossed with DKO mice. Strikingly, the compound human HIP1 transgenic DKO mice were completely free from dwarfism and spinal defects. This successful rescue demonstrates that the human HIP1 protein shares some interchangeable functions with both HIP1 and HIP1r in vivo. In addition, we conclude that the degenerative phenotypes seen in the DKO mice are due mainly to HIP1 and HIP1r protein deficiency rather than altered expression of neighboring genes or disrupted intronic elements.

Interaction investigations of HipA binding to HipB dimer and HipB dimer + DNA complex: a molecular dynamics simulation study.

PubMed

Li, Chaoqun; Wang, Yaru; Wang, Yan; Chen, Guangju

2013-11-01

We carried out molecular dynamics simulations and free energy calculations for a series of ternary and diplex models for the HipA protein, HipB dimer, and DNA molecule to address the mechanism of HipA sequestration and the binding order of events from apo HipB/HipA to 2HipA + HipB dimer + DNA complex. The results revealed that the combination of DNA with the HipB dimer is energetically favorable for the combination of HipB dimer with HipA protein. The binding of DNA to HipB dimer induces a long-range allosteric communication from the HipB2 -DNA interface to the HipA-HipB2 interface, which involves the closeness of α1 helices of HipB dimer to HipA protein and formations of extra hydrogen bonds in the HipA-HipB2 interface through the extension of α2/3 helices in the HipB dimer. These simulated results suggested that the DNA molecule, as a regulative media, modulates the HipB dimer conformation, consequently increasing the interactions of HipB dimer with the HipA proteins, which explains the mechanism of HipA sequestration reported by the previous experiment. Simultaneously, these simulations also explored that the thermodynamic binding order in a simulated physiological environment, that is, the HipB dimer first bind to DNA to form HipB dimer + DNA complex, then capturing strongly the HipA proteins to form a ternary complex, 2HipA + HipB dimer + DNA, for sequestrating HipA in the nucleoid. Copyright © 2013 John Wiley & Sons, Ltd.

Total Hip Arthroplasty in Patients With Avascular Necrosis After Hematopoietic Stem Cell Transplantation.

PubMed

Vijapura, Anita; Levine, Harlan B; Donato, Michele; Hartzband, Mark A; Baker, Melissa; Klein, Gregg R

2018-03-01

The immunosuppressive regimens required for hematopoietic stem cell transplantation predispose recipients to complications, including avascular necrosis. Cancer-related comorbidities, immunosuppression, and poor bone quality theoretically increase the risk for perioperative medical complications, infection, and implant-related complications in total joint arthroplasty. This study reviewed 20 primary total hip arthroplasties for avascular necrosis in 14 patients. Outcomes were assessed at routine clinical visits and Harris hip scores were calculated. Follow-up radiographs were evaluated for component malposition, loosening, polyethylene wear, and osteolysis. Average follow-up was 44.5 months for all patients. Postoperative clinical follow-up revealed good to excellent outcomes, with significant improvement in functional outcome scores. There were no periprosthetic infections or revisions for aseptic loosening. There was 1 dislocation on postoperative day 40, which was treated successfully with a closed reduction. Two patients with a prior history of venous thromboembolism developed a pulmonary embolus on postoperative day 13 and 77, respectively. Four patients died several months to years after arthroplasty of complications unrelated to the surgical procedure. Total hip arthroplasty can both be safely performed and greatly improve quality of life in recipients of hematopoietic stem cell transplantation who develop avascular necrosis. However, prolonged venous thromboembolism prophylaxis should be carefully considered in this high-risk patient population. [Orthopedics. 2018; 41(2):e257-e261.]. Copyright 2018, SLACK Incorporated.

Dislocation structure produced by an ultrashort shock pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsuda, Tomoki, E-mail: t-matsu@mapse.eng.osaka-u.ac.jp; Hirose, Akio; Sano, Tomokazu

We found an ultrashort shock pulse driven by a femtosecond laser pulse on iron generates a different dislocation structure than the shock process which is on the nanosecond timescale. The ultrashort shock pulse produces a highly dense dislocation structure that varies by depth. According to transmission electron microscopy, dislocations away from the surface produce microbands via a network structure similar to a long shock process, but unlike a long shock process dislocations near the surface have limited intersections. Considering the dislocation motion during the shock process, the structure near the surface is attributed to the ultrashort shock duration. This approachmore » using an ultrashort shock pulse will lead to understanding the whole process off shock deformation by clarifying the early stage.« less

Dislocation filtering in GaN nanostructures.

PubMed

Colby, Robert; Liang, Zhiwen; Wildeson, Isaac H; Ewoldt, David A; Sands, Timothy D; García, R Edwin; Stach, Eric A

2010-05-12

Dislocation filtering in GaN by selective area growth through a nanoporous template is examined both by transmission electron microscopy and numerical modeling. These nanorods grow epitaxially from the (0001)-oriented GaN underlayer through the approximately 100 nm thick template and naturally terminate with hexagonal pyramid-shaped caps. It is demonstrated that for a certain window of geometric parameters a threading dislocation growing within a GaN nanorod is likely to be excluded by the strong image forces of the nearby free surfaces. Approximately 3000 nanorods were examined in cross-section, including growth through 50 and 80 nm diameter pores. The very few threading dislocations not filtered by the template turn toward a free surface within the nanorod, exiting less than 50 nm past the base of the template. The potential active region for light-emitting diode devices based on these nanorods would have been entirely free of threading dislocations for all samples examined. A greater than 2 orders of magnitude reduction in threading dislocation density can be surmised from a data set of this size. A finite element-based implementation of the eigenstrain model was employed to corroborate the experimentally observed data and examine a larger range of potential nanorod geometries, providing a simple map of the different regimes of dislocation filtering for this class of GaN nanorods. These results indicate that nanostructured semiconductor materials are effective at eliminating deleterious extended defects, as necessary to enhance the optoelectronic performance and device lifetimes compared to conventional planar heterostructures.

Dislocation evolution in 316 L stainless steel during multiaxial ratchetting deformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong Yawei; Kang Guozheng, E-mail: guozhengkang@yahoo.com.cn; Liu Yujie

2012-03-15

Dislocation patterns and their evolutions in 316 L stainless steel during the multiaxial ratchetting deformation were observed by transmission electron microscopy (TEM). The microscopic observations indicate that the dislocation evolution presented during the multiaxial ratchetting with four kinds of multiaxial loading paths is similar to that in the uniaxial case [G. Z. Kang et al., Mater Sci Eng A 527 (2010) 5952]. That is, dislocation networks and dislocation tangles are formed quickly by the multiple-slip and cross-slip of dislocation activated by applied multiaxial stress; and then polarized patterns such as dislocation walls and elongated incipient dislocation cells are formed atmore » the last stage of multiaxial ratchetting. The dislocation patterns evolve more quickly from the modes at low dislocation density to the ones at high density during the multiaxial ratchetting than that in the uniaxial case, and some traces of multiple-slip are observed in the multiaxial ones. The dislocation evolution during the multiaxial ratchetting deformation is summarized by comparing the observed dislocation patterns with those presented in the multiaxial strain-controlled and symmetrical stress-controlled cyclic tests. The multiaxial ratchetting of 316 L stainless steel can be microscopically and qualitatively explained by the observed evolution of dislocation patterns. - Highlights: Black-Right-Pointing-Pointer Dislocation patterns change from lines and nets to tangles, walls and cells. Black-Right-Pointing-Pointer Dislocation patterns evolve quicker in the multiaxial case. Black-Right-Pointing-Pointer Aligned dislocation arrays and some traces of multiple slips are observed. Black-Right-Pointing-Pointer Heterogeneous dislocation patterns result in the multiaxial ratchetting.« less

Quantitative measurement and analysis for detection and treatment planning of developmental dysplasia of the hip

NASA Astrophysics Data System (ADS)

Liu, Xin; Lu, Hongbing; Chen, Hanyong; Zhao, Li; Shi, Zhengxing; Liang, Zhengrong

2009-02-01

Developmental dysplasia of the hip is a congenital hip joint malformation affecting the proximal femurs and acetabulum that are subluxatable, dislocatable, and dislocated. Conventionally, physicians made diagnoses and treatments only based on findings from two-dimensional (2D) images by manually calculating clinic parameters. However, anatomical complexity of the disease and the limitation of current standard procedures make accurate diagnosis quite difficultly. In this study, we developed a system that provides quantitative measurement of 3D clinical indexes based on computed tomography (CT) images. To extract bone structure from surrounding tissues more accurately, the system firstly segments the bone using a knowledge-based fuzzy clustering method, which is formulated by modifying the objective function of the standard fuzzy c-means algorithm with additive adaptation penalty. The second part of the system calculates automatically the clinical indexes, which are extended from 2D to 3D for accurate description of spatial relationship between femurs and acetabulum. To evaluate the system performance, experimental study based on 22 patients with unilateral or bilateral affected hip was performed. The results of 3D acetabulum index (AI) automatically provided by the system were validated by comparison with 2D results measured by surgeons manually. The correlation between the two results was found to be 0.622 (p<0.01).

Spine–hip relations in patients with hip osteoarthritis

PubMed Central

Rivière, Charles; Lazic, Stefan; Dagneaux, Louis; Van Der Straeten, Catherine; Cobb, Justin; Muirhead-Allwood, Sarah

2018-01-01

Patients with hip osteoarthritis often have an abnormal spine-hip relation (SHR), meaning the presence of a clinically deleterious spine-hip and/or hip-spine syndrome. Definition of the individual SHR is ideally done using the EOS® imaging system or, if not available, with conventional lumbopelvic lateral radiographs. By pre-operatively screening patients with abnormal SHR, it is possible to refine total hip replacement (THR) surgical planning, which may improve outcomes. An important component of the concept of kinematically aligned total hip arthroplasty (KA THA) consists of defining the optimal acetabular cup design and orientation based on the assessment of an individual’s SHR, and use of the transverse acetabular ligament to adjust the cup positioning. The Bordeaux classification might advance the understanding of SHR and hopefully help improve THR outcomes. Cite this article: EFORT Open Rev 2018;3:39-44. DOI: 10.1302/2058-5241.3.170020 PMID:29657844

Collective behaviour of dislocations in a finite medium

NASA Astrophysics Data System (ADS)

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

2014-04-01

We derive the grand-canonical partition function of straight and parallel dislocation lines without making a priori assumptions on the temperature regime. Such a systematic derivation for dislocations has, to the best of our knowledge, not been carried out before, and several conflicting assumptions on the free energy of dislocations have been made in the literature. Dislocations have gained interest as they are the carriers of plastic deformation in crystalline materials and solid polymers, and they constitute a prototype system for two-dimensional Coulomb particles. Our microscopic starting level is the description of dislocations as used in the discrete dislocation dynamics (DDD) framework. The macroscopic level of interest is characterized by the temperature, the boundary deformation and the dislocation density profile. By integrating over state space, we obtain a field theoretic partition function, which is a functional integral of the Boltzmann weight over an auxiliary field. The Hamiltonian consists of a term quadratic in the field and an exponential of this field. The partition function is strongly non-local, and reduces in special cases to the sine-Gordon model. Moreover, we determine implicit expressions for the response functions and the dominant scaling regime for metals, namely the low-temperature regime.

Association of hip pain with radiographic evidence of hip osteoarthritis: diagnostic test study

PubMed Central

Nevitt, Michael C; Niu, Jingbo; Clancy, Mary M; Lane, Nancy E; Link, Thomas M; Vlad, Steven; Tolstykh, Irina; Jungmann, Pia M.; Felson, David T; Guermazi, Ali

2015-01-01

Study question Is there concordance between hip pain and radiographic hip osteoarthritis? Methods In this diagnostic test study, pelvic radiographs were assessed for hip osteoarthritis in two cohorts: the Framingham Osteoarthritis Study (community of Framingham, Massachusetts) and the Osteoarthritis Initiative (a multicenter longitudinal cohort study of osteoarthritis in the United States). Using visual representation of the hip joint, participants reported whether they had hip pain on most days and the location of the pain: anterior, groin, lateral, buttocks, or low back. In the Framingham study, participants with hip pain were also examined for hip pain with internal rotation. The authors analysed the agreement between radiographic hip osteoarthritis and hip pain, and for those with hip pain suggestive of hip osteoarthritis they calculated the sensitivity, specificity, positive predictive value, and negative predictive value of radiographs as the diagnostic test. Study answer and limitations In the Framingham study (n=946), only 15.6% of hips in patients with frequent hip pain showed radiographic evidence of hip osteoarthritis, and 20.7% of hips with radiographic hip osteoarthritis were frequently painful. The sensitivity of radiographic hip osteoarthritis for hip pain localised to the groin was 36.7%, specificity 90.5%, positive predictive value 6.0%, and negative predictive value 98.9%. Results did not differ much for hip pain at other locations or for painful internal rotation. In the Osteoarthritis Initiative study (n=4366), only 9.1% of hips in patients with frequent pain showed radiographic hip osteoarthritis, and 23.8% of hips with radiographic hip osteoarthritis were frequently painful. The sensitivity of definite radiographic hip osteoarthritis for hip pain localised to the groin was 16.5%, specificity 94.0%, positive predictive value 7.1%, and negative predictive value 97.6%. Results also did not differ much for hip pain at other locations. What this

Singularity-free dislocation dynamics with strain gradient elasticity

NASA Astrophysics Data System (ADS)

Po, Giacomo; Lazar, Markus; Seif, Dariush; Ghoniem, Nasr

2014-08-01

The singular nature of the elastic fields produced by dislocations presents conceptual challenges and computational difficulties in the implementation of discrete dislocation-based models of plasticity. In the context of classical elasticity, attempts to regularize the elastic fields of discrete dislocations encounter intrinsic difficulties. On the other hand, in gradient elasticity, the issue of singularity can be removed at the outset and smooth elastic fields of dislocations are available. In this work we consider theoretical and numerical aspects of the non-singular theory of discrete dislocation loops in gradient elasticity of Helmholtz type, with interest in its applications to three dimensional dislocation dynamics (DD) simulations. The gradient solution is developed and compared to its singular and non-singular counterparts in classical elasticity using the unified framework of eigenstrain theory. The fundamental equations of curved dislocation theory are given as non-singular line integrals suitable for numerical implementation using fast one-dimensional quadrature. These include expressions for the interaction energy between two dislocation loops and the line integral form of the generalized solid angle associated with dislocations having a spread core. The single characteristic length scale of Helmholtz elasticity is determined from independent molecular statics (MS) calculations. The gradient solution is implemented numerically within our variational formulation of DD, with several examples illustrating the viability of the non-singular solution. The displacement field around a dislocation loop is shown to be smooth, and the loop self-energy non-divergent, as expected from atomic configurations of crystalline materials. The loop nucleation energy barrier and its dependence on the applied shear stress are computed and shown to be in good agreement with atomistic calculations. DD simulations of Lome-Cottrell junctions in Al show that the strength of the

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

PubMed

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

Hip fractures. Epidemiology, risk factors, falls, energy absorption, hip protectors, and prevention.

PubMed

Lauritzen, J B

1997-04-01

The present review summarizes the pathogenic mechanisms leading to hip fracture based on epidemiological, experimental, and controlled studies. The estimated lifetime risk of hip fracture is about 14% in postmenopausal women and 6% in men. The incidence of hip fractures increases exponentially with aging, but the time-trend in increasing age-specific incidence may not be a universal phenomenon. Postmenopausal women suffering earlier non-hip fractures have an increased risk of later hip fracture. The relative risk being highest within the first years following the fracture. Nursing home residents have a high risk of hip fracture (annual rate of 5-6%), and the incidence of falls is about 1,500 falls/1,000 persons/year. Most hip fractures are a result of a direct trauma against the hip. The incidence of falls on the hip among nursing home residents is about 290 falls/1,000 persons/year and about 24% of these impacts lead to hip fracture. The force acting on the hip may reach 3.7 kN in falls on the hip from standing height, which means that only susceptible subjects will sustain a hip fracture in such falls. The effective load acting on the hip is 35% of the body weight in unprotected falls on the hip. Women with hip fractures have a lower body weight compared with controls, and they may also have less soft tissue covering the hip even when adjusted for body mass index, indicating a more android body habitus. Experimental studies show that the passive energy absorption in soft tissue covering the hip may influence the risk of hip fracture, and being an important determinant for the development of hip fracture, maybe more important than bone strength. External hip protectors were developed and tested in an open randomised nursing home study. The rate of hip fractures was reduced by 50%, corresponding to 9 out of 247 residents saved from sustaining a hip fracture. The review points to the essentials of the development of hip fracture, which constitutes; risk of fall

Modeling of dislocation dynamics in germanium Czochralski growth

NASA Astrophysics Data System (ADS)

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.

[Which hip articulation bearing for which patient? : Tribology of the future].

PubMed

Morlock, M M; Bishop, N; Kaddick, C

2011-12-01

Replacement of the hip joint has become an exceptionally successful procedure since the inauguration of the low friction principle by Charnley. Aseptic osteolysis and joint dislocation have been addressed by the development of wear-optimized materials and the introduction of larger heads. As an increase in head diameter against polyethylene causes wear increase, larger hard-on-hard bearings were introduced, which exhibit reduced wear and reduced dislocation risk with increasing head diameter. These findings were derived from standard simulator testing, not sufficiently considering the risk of fluid film breakdown under adverse conditions, which can cause a dramatic increase in wear and friction proportional to the head diameter. Such adverse conditions can occur clinically in patients due to several factors and have caused the presently observed unexpected problems with these new designs. Standardized preclinical testing has to be viewed as a minimum requirement but certainly not as a guarantee for the clinical success of new materials and designs even if the testing is adapted to the current patient requirements, which is presently not the case. The future of tribology lies in the prevention of adverse conditions in patients, the improvement and optimized use of proven existing materials and not in the use of new materials.

Hip impingement: identifying and treating a common cause of hip pain.

PubMed

Kuhlman, Geoffrey S; Domb, Benjamin G

2009-12-15

Femoroacetabular impingement, also known as hip impingement, is the abutment of the acetabular rim and the proximal femur. Hip impingement is increasingly recognized as a common etiology of hip pain in athletes, adolescents, and adults. It injures the labrum and articular cartilage, and can lead to osteoarthritis of the hip if left untreated. Patients with hip impingement often report anterolateral hip pain. Common aggravating activities include prolonged sitting, leaning forward, getting in or out of a car, and pivoting in sports. The use of flexion, adduction, and internal rotation of the supine hip typically reproduces the pain. Radiography, magnetic resonance arthrography, and injection of local anesthetic into the hip joint confirm the diagnosis. Pain may improve with physical therapy. Treatment often requires arthroscopy, which typically allows patients to resume premorbid physical activities. An important goal of arthroscopy is preservation of the hip joint. Whether arthroscopic treatment prevents or delays osteoarthritis of the hip is unknown.

Axillary artery injury secondary to inferior shoulder dislocation.

PubMed

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.

Hip morphology in elite golfers: asymmetry between lead and trail hips.

PubMed

Dickenson, Edward; O'Connor, Philip; Robinson, Philip; Campbell, Robert; Ahmed, Imran; Fernandez, Miguel; Hawkes, Roger; Charles, Hutchinson; Griffin, Damian

2016-09-01

During a golf swing, the lead hip (left hip in a right-handed player) rotates rapidly from external to internal rotation, while the opposite occurs in the trail hip. This study assessed the morphology and pathology of golfers' hips comparing lead and trail hips. A cohort of elite golfers were invited to undergo MRI of their hips. Hip morphology was evaluated by measuring acetabular depth (pincer shape=negative measure), femoral neck antetorsion (retrotorsion=negative measure) and α angles (cam morphology defined as α angle >55° anteriorly) around the axis of the femoral neck. Consultant musculoskeletal radiologists determined the presence of intra-articular pathology. 55 players (mean age 28 years, 52 left hip lead) underwent MRI. No player had pincer morphology, 2 (3.6%) had femoral retrotorsion and 9 (16%) had cam morphology. 7 trail hips and 2 lead hips had cam morphology (p=0.026). Lead hip femoral neck antetorsion was 16.7° compared with 13.0° in the trail hip (p<0.001). The α angles around the femoral neck were significantly lower in the lead compared with trail hips (p<0.001), with the greatest difference noted in the anterosuperior portion of the head neck junction; 53° vs 58° (p<0.001) and 43° vs 47° (p<0.001). 37% of trail and 16% of lead hips (p=0.038) had labral tears. Golfers' lead and trail hips have different morphology. This is the first time side-to-side asymmetry of cam prevalence has been reported. The trail hip exhibited a higher prevalence of labral tears. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Implementation of the nudged elastic band method in a dislocation dynamics formalism: Application to dislocation nucleation

NASA Astrophysics Data System (ADS)

Geslin, Pierre-Antoine; Gatti, Riccardo; Devincre, Benoit; Rodney, David

2017-11-01

We propose a framework to study thermally-activated processes in dislocation glide. This approach is based on an implementation of the nudged elastic band method in a nodal mesoscale dislocation dynamics formalism. Special care is paid to develop a variational formulation to ensure convergence to well-defined minimum energy paths. We also propose a methodology to rigorously parametrize the model on atomistic data, including elastic, core and stacking fault contributions. To assess the validity of the model, we investigate the homogeneous nucleation of partial dislocation loops in aluminum, recovering the activation energies and loop shapes obtained with atomistic calculations and extending these calculations to lower applied stresses. The present method is also applied to heterogeneous nucleation on spherical inclusions.

Isolated dorsal dislocation of the tarsal naviculum

PubMed Central

Hamdi, Kaziz; Hazem, Ben Ghozlen; Yadh, Zitoun; Faouzi, Abid

2015-01-01

Isolated dislocation of the tarsal naviculum is an unusual injury, scarcely reported in the literature. The naviculum is surrounded by the rigid bony and ligamentous support hence fracture dislocation is more common than isolated dislocation. The mechanism and treatment options remain unclear. In this case report, we describe a 31 year old man who sustained an isolated dorsal dislocation of the left tarsal naviculum, without fracture, when he was involved in a motor vehicle collision. The reported mechanism of the dislocation is a hyper plantar flexion force applied to the midfoot, resulting in a transient disruption of the ligamentous support of the naviculum bone, with dorsal displacement of the bone. The patient was treated with open reduction and Krischner-wire fixation of the navicular after the failure of closed reduction. The wires were removed after 6 weeks postoperatively. Physiotherapy for stiffness and midfoot pain was recommended for 2 months. At 6 months postoperatively, limping, midfoot pain and weakness were reported, no X-ray abnormalities were found. The patient returned to his obvious activities with a normal range of motion. PMID:26806978

21 CFR 888.3400 - Hip joint femoral (hemi-hip) metallic resurfacing prosthesis.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hip joint femoral (hemi-hip) metallic resurfacing... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3400 Hip joint femoral (hemi-hip) metallic resurfacing prosthesis. (a) Identification. A hip joint femoral (hemi-hip...

21 CFR 888.3370 - Hip joint (hemi-hip) acetabular metal cemented prosthesis.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hip joint (hemi-hip) acetabular metal cemented... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3370 Hip joint (hemi-hip) acetabular metal cemented prosthesis. (a) Identification. A hip joint (hemi-hip) acetabular...

A hierarchical dislocation-grain boundary interaction model based on 3D discrete dislocation dynamics and molecular dynamics

NASA Astrophysics Data System (ADS)

Gao, Yuan; Zhuang, Zhuo; You, XiaoChuan

2011-04-01

We develop a new hierarchical dislocation-grain boundary (GB) interaction model to predict the mechanical behavior of polycrystalline metals at micro and submicro scales by coupling 3D Discrete Dislocation Dynamics (DDD) simulation with the Molecular Dynamics (MD) simulation. At the microscales, the DDD simulations are responsible for capturing the evolution of dislocation structures; at the nanoscales, the MD simulations are responsible for obtaining the GB energy and ISF energy which are then transferred hierarchically to the DDD level. In the present model, four kinds of dislocation-GB interactions, i.e. transmission, absorption, re-emission and reflection, are all considered. By this methodology, the compression of a Cu micro-sized bi-crystal pillar is studied. We investigate the characteristic mechanical behavior of the bi-crystal compared with that of the single-crystal. Moreover, the comparison between the present penetrable model of GB and the conventional impenetrable model also shows the accuracy and efficiency of the present model.

Thermodynamic theory of dislocation-enabled plasticity

NASA Astrophysics Data System (ADS)

Langer, J. S.

2017-11-01

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.

Elasticity and dislocation inelasticity of crystals

NASA Astrophysics Data System (ADS)

Nikanorov, S. P.; Kardashev, B. K.

The use of methods of physical acoustics for studying the elasticity and dislocation inelasticity of crystals is discussed, as is the application of the results of such studies to the analysis of interatomic and lattice defect interactions. The analysis of the potential functions determining the energy of interatomic interactions is based on an analysis of the elastic properties of crystals over a wide temperature range. The data on the dislocation structure and the interaction between dislocations and point defects are obtained from a study of inelastic effects. Particular attention is given to the relationship between microplastic effects under conditions of elastic oscillations and the initial stage of plastic deformation.

Pair Interaction of Dislocations in Two-Dimensional Crystals

NASA Astrophysics Data System (ADS)

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.

Thermal activation of dislocations in large scale obstacle bypass

NASA Astrophysics Data System (ADS)

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.

Walking patterns and hip contact forces in patients with hip dysplasia.

PubMed

Skalshøi, Ole; Iversen, Christian Hauskov; Nielsen, Dennis Brandborg; Jacobsen, Julie; Mechlenburg, Inger; Søballe, Kjeld; Sørensen, Henrik

2015-10-01

Several studies have investigated walking characteristics in hip dysplasia patients, but so far none have described all hip rotational degrees of freedom during the whole gait cycle. This descriptive study reports 3D joint angles and torques, and furthermore extends previous studies with muscle and joint contact forces in 32 hip dysplasia patients and 32 matching controls. 3D motion capture data from walking and standing trials were analysed. Hip, knee, ankle and pelvis angles were calculated with inverse kinematics for both standing and walking trials. Hip, knee and ankle torques were calculated with inverse dynamics, while hip muscle and joint contact forces were calculated with static optimisation for the walking trials. No differences were found between the two groups while standing. While walking, patients showed decreased hip extension, increased ankle pronation and increased hip abduction and external rotation torques. Furthermore, hip muscle forces were generally lower and shifted to more posteriorly situated muscles, while the hip joint contact force was lower and directed more superiorly. During walking, patients showed lower and more superiorly directed hip joint contact force, which might alleviate pain from an antero-superiorly degenerated joint. Copyright © 2015 Elsevier B.V. All rights reserved.

21 CFR 888.3370 - Hip joint (hemi-hip) acetabular metal cemented prosthesis.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Hip joint (hemi-hip) acetabular metal cemented... (hemi-hip) acetabular metal cemented prosthesis. (a) Identification. A hip joint (hemi-hip) acetabular metal cemented prosthesis is a device intended to be implanted to replace a portion of the hip joint...

Influence of strain on dislocation core in silicon

NASA Astrophysics Data System (ADS)

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.

The relationship between strain geometry and geometrically necessary dislocations

NASA Astrophysics Data System (ADS)

Hansen, Lars; Wallis, David

2016-04-01

The kinematics of past deformations are often a primary goal in structural analyses of strained rocks. Details of the strain geometry, in particular, can help distinguish hypotheses about large-scale tectonic phenomena. Microstructural indicators of strain geometry have been heavily utilized to investigate large-scale kinematics. However, many of the existing techniques require structures for which the initial morphology is known, and those structures must undergo the same deformation as imposed macroscopically. Many deformed rocks do not exhibit such convenient features, and therefore the strain geometry is often difficult (if not impossible) to ascertain. Alternatively, crystallographic textures contain information about the strain geometry, but the influence of strain geometry can be difficult to separate from other environmental factors that might affect slip system activity and therefore the textural evolution. Here we explore the ability for geometrically necessary dislocations to record information about the deformation geometry. It is well known that crystallographic slip due to the motion of dislocations yields macroscopic plastic strain, and the mathematics are established to relate dislocation glide on multiple slip systems to the strain tensor of a crystal. This theoretical description generally assumes that dislocations propagate across the entire crystal. However, at any point during the deformation, dislocations are present that have not fully transected the crystal, existing either as free dislocations or as dislocations organized into substructures like subgrain boundaries. These dislocations can remain in the lattice after deformation if the crystal is quenched sufficiently fast, and we hypothesize that this residual dislocation population can be linked to the plastic strain geometry in a quantitative manner. To test this hypothesis, we use high-resolution electron backscatter diffraction to measure lattice curvatures in experimentally deformed

Dynamic Hip Kinematics During the Golf Swing After Total Hip Arthroplasty.

PubMed

Hara, Daisuke; Nakashima, Yasuharu; Hamai, Satoshi; Higaki, Hidehiko; Ikebe, Satoru; Shimoto, Takeshi; Yoshimoto, Kensei; Iwamoto, Yukihide

2016-07-01

Although most surgeons allow their patients to play golf after total hip arthroplasty (THA), the effect on the implant during the golf swing is still unclear. To evaluate hip kinematics during the golf swing after THA. Descriptive laboratory study. Eleven hips in 9 patients who underwent primary THA were analyzed. All patients were right-handed recreational golfers, and these 11 hips included 6 right hips and 5 left hips. Periodic radiographic images of the golf swing were taken using a flat-panel x-ray detector. Movements of the hip joint and components were assessed using 3-dimensional-to-2-dimensional model-to-image registration techniques. Liner-to-neck contact and translation of the femoral head with respect to the acetabular cup (cup-head translation) were examined. Hip kinematics, orientation of components, and maximum cup-head translation were compared between patients with and without liner-to-neck contact. On average, the golf swing produced approximately 50° of axial rotation in both lead and trail hips. Liner-to-neck contact was observed in 4 hips with elevated rim liners (2 lead hips and 2 trail hips) at maximum external rotation. Neither bone-to-bone nor bone-to-implant contact was observed at any phases of the golf swing in any of the hips. Four hips with liner-to-neck contact had significantly larger maximum external rotation (37.9° ± 7.0° vs 20.6° ± 9.9°, respectively; P = .01) and more cup anteversion (26.5° ± 6.1° vs 10.8° ± 8.9°, respectively; P = .01) than hips without liner-to-neck contact. No significant differences between hips with and without contact were found for cup inclination (42.0° ± 2.5° vs 38.1° ± 5.5°, respectively; P = .22), combined anteversion (45.3° ± 8.9° vs 51.4° ± 7.9°, respectively; P = .26), or maximum cup-head translation (1.3 ± 0.3 mm vs 1.5 ± 0.4 mm, respectively; P = .61). In this analysis, the golf swing did not produce excessive hip rotation or cup-head translation in any hips. However

[Experimental study of dislocations of the scapulohumeral joint].

PubMed

Gagey, O; Gagey, N; Boisrenoult, P; Hue, E; Mazas, F

1993-01-01

One may produce easily an experimental dislocation (anterior or erecta) of the scapulohumeral joint. The authors discuss, the experimental model then they describe the anatomical lesion produced through the experimental dislocation of 32 shoulders and the correlation observed after RMI assessment of 24 recurrent dislocations. The tear of the inferior glenohumeral ligament is constant, in 20 per cent of the cases the tear lies on the anterior aspect of the glenoid, in the other cases the tear was found on its humeral side. Whatever the situation of the tear of the inferior glenohumeral ligament, the lesion of the labrum was constant. The erecta dislocation was produced with the same movement but with a particular tear of the glenohumeral ligament: the tear was longitudinal. The experimental dislocation needs, in 7 or 8 cases, a desinsertion of the deep aspect of the rotator cuff. The Hill Sachs lesion occurs when the humerus falls along the chest wall after the dislocation. In 50 per cent of the patients, MRI shows modifications of the cuff which are compatible with our results. Hills Sachs lesions appear to be constant after MRI examination.

How to identify dislocations in molecular dynamics simulations?

NASA Astrophysics Data System (ADS)

Li, Duo; Wang, FengChao; Yang, ZhenYu; Zhao, YaPu

2014-12-01

Dislocations are of great importance in revealing the underlying mechanisms of deformed solid crystals. With the development of computational facilities and technologies, the observations of dislocations at atomic level through numerical simulations are permitted. Molecular dynamics (MD) simulation suggests itself as a powerful tool for understanding and visualizing the creation of dislocations as well as the evolution of crystal defects. However, the numerical results from the large-scale MD simulations are not very illuminating by themselves and there exist various techniques for analyzing dislocations and the deformed crystal structures. Thus, it is a big challenge for the beginners in this community to choose a proper method to start their investigations. In this review, we summarized and discussed up to twelve existing structure characterization methods in MD simulations of deformed crystal solids. A comprehensive comparison was made between the advantages and disadvantages of these typical techniques. We also examined some of the recent advances in the dynamics of dislocations related to the hydraulic fracturing. It was found that the dislocation emission has a significant effect on the propagation and bifurcation of the crack tip in the hydraulic fracturing.

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

PubMed

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

MedlinePlus

... 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. ...

The strength and dislocation microstructure evolution in superalloy microcrystals

NASA Astrophysics Data System (ADS)

Hussein, Ahmed M.; Rao, Satish I.; Uchic, Michael D.; Parthasarathay, Triplicane A.; El-Awady, Jaafar A.

2017-02-01

In this work, the evolution of the dislocations microstructure in single crystal two-phase superalloy microcrystals under monotonic loading has been studied using the three-dimensional discrete dislocation dynamics (DDD) method. The DDD framework has been extended to properly handle the collective behavior of dislocations and their interactions with large collections of arbitrary shaped precipitates. Few constraints are imposed on the initial distribution of the dislocations or the precipitates, and the extended DDD framework can support experimentally-obtained precipitate geometries. Full tracking of the creation and destruction of anti-phase boundaries (APB) is accounted for. The effects of the precipitate volume fraction, APB energy, precipitate size, and crystal size on the deformation of superalloy microcrystals have been quantified. Correlations between the precipitate microstructure and the dominant deformation features, such as dislocation looping versus precipitate shearing, are also discussed. It is shown that the mechanical strength is independent of the crystal size, increases linearly with increasing the volume fraction, follows a near square-root relationship with the APB energy and an inverse square-root relationship with the precipitate size. Finally, the flow strength in simulations having initial dislocation pair sources show a flow strength that is about one half of that predicted from simulations starting with single dislocation sources. The method developed can be used, with minimal extensions, to simulate dislocation microstructure evolution in general multiphase materials.

FUNCTIONAL OUTCOMES OF HIP ARTHROSCOPY IN AN ACTIVE DUTY MILITARY POPULATION UTILIZING A CRITERION-BASED EARLY WEIGHT BEARING PROGRESSION

PubMed Central

Jacobs, Jeremy M.; Evanson, J. Richard; Pniewski, Josh; Dickston, Michelle L.; Mueller, Terry; Bojescul, John A.

2017-01-01

Introduction Hip arthroscopy allows surgeons to address intra-articular pathology of the hip while avoiding more invasive open surgical dislocation. However the post-operative rehabilitation protocols have varied greatly in the literature, with many having prolonged periods of limited motion and weight bearing. Purpose The purpose of this study was to describe a criterion-based early weight bearing protocol following hip arthroscopy and investigate functional outcomes in the subjects who were active duty military. Methods Active duty personnel undergoing hip arthroscopy for symptomatic femoroacetabular impingement were prospectively assessed in a controlled environment for the ability to incorporate early postoperative weight-bearing with the following criteria: no increased pain complaint with weight bearing and normalized gait pattern. Modified Harris Hip (HHS) and Hip Outcome score (HOS) were performed preoperatively and at six months post-op. Participants were progressed with a standard hip arthroscopy protocol. Hip flexion was limited to not exceed 90 degrees for the first three weeks post-op, with progression back to running beginning at three months. Final discharge was dependent upon the ability to run two miles at military specified pace and do a single leg broad jump within six inches of the contralateral leg without an increase in pain. Results Eleven participants met inclusion criteria over the study period. Crutch use was discontinued at an average of five days following surgery based on established weight bearing criteria. Only one participant required continued crutch use at 15 days. Participants’ functional outcome was improved postoperatively, as demonstrated by significant increases in HOS and HHS. At the six month follow up, eight of 11 participants were able to take and complete a full Army Physical Fitness Test. Conclusions Following completion of the early weight bearing rehabilitation protocol, 81% of participants were able to progress to

FUNCTIONAL OUTCOMES OF HIP ARTHROSCOPY IN AN ACTIVE DUTY MILITARY POPULATION UTILIZING A CRITERION-BASED EARLY WEIGHT BEARING PROGRESSION.

PubMed

Shaw, K Aaron; Jacobs, Jeremy M; Evanson, J Richard; Pniewski, Josh; Dickston, Michelle L; Mueller, Terry; Bojescul, John A

2017-10-01

Hip arthroscopy allows surgeons to address intra-articular pathology of the hip while avoiding more invasive open surgical dislocation. However the post-operative rehabilitation protocols have varied greatly in the literature, with many having prolonged periods of limited motion and weight bearing. The purpose of this study was to describe a criterion-based early weight bearing protocol following hip arthroscopy and investigate functional outcomes in the subjects who were active duty military. Active duty personnel undergoing hip arthroscopy for symptomatic femoroacetabular impingement were prospectively assessed in a controlled environment for the ability to incorporate early postoperative weight-bearing with the following criteria: no increased pain complaint with weight bearing and normalized gait pattern. Modified Harris Hip (HHS) and Hip Outcome score (HOS) were performed preoperatively and at six months post-op. Participants were progressed with a standard hip arthroscopy protocol. Hip flexion was limited to not exceed 90 degrees for the first three weeks post-op, with progression back to running beginning at three months. Final discharge was dependent upon the ability to run two miles at military specified pace and do a single leg broad jump within six inches of the contralateral leg without an increase in pain. Eleven participants met inclusion criteria over the study period. Crutch use was discontinued at an average of five days following surgery based on established weight bearing criteria. Only one participant required continued crutch use at 15 days. Participants' functional outcome was improved postoperatively, as demonstrated by significant increases in HOS and HHS. At the six month follow up, eight of 11 participants were able to take and complete a full Army Physical Fitness Test. Following completion of the early weight bearing rehabilitation protocol, 81% of participants were able to progress to full weight bearing by four days post

Thermodynamic theory of dislocation-enabled plasticity

DOE PAGES

Langer, J. S.

2017-11-30

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,more » yielding transitions, and adiabatic shear banding.« less

Rare Inferior Shoulder Dislocation (Luxatio Erecta)

PubMed Central

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

Hip instability: a review of hip dysplasia and other contributing factors

PubMed Central

Kraeutler, Matthew J.; Garabekyan, Tigran; Pascual-Garrido, Cecilia; Mei-Dan, Omer

2016-01-01

Summary Background Hip instability has classically been associated with developmental dysplasia of the hip (DDH) in newborns and children. However, numerous factors may contribute to hip instability in children, adolescents, and adults. Purpose This review aims to concisely present the literature on hip instability in patients of all ages in order to guide health care professionals in the appropriate diagnosis and treatment of the various disorders which may contribute to an unstable hip. Methods We reviewed the literature on the diagnosis and surgical management of hip dysplasia and other causes of hip instability. Conclusions Multiple intra- and extra-articular variables may contribute to hip instability, including acetabular bony coverage, femoral torsion, femoroacetabular impingement, and soft tissue laxity. Physical examination and advanced imaging studies are essential to accurately diagnose the pathology contributing to a patient’s unstable hip. Conservative management, including activity modification and physical therapy, may be used as a first-line treatment in patients with intra-articular hip pathology. Patients who continue to experience symptoms of pain or instability should proceed with arthroscopic or open surgical treatment aimed at correcting the underlying pathology. Level of evidence V. PMID:28066739

Early Outcomes of Primary Total Hip Arthroplasty After Prior Lumbar Spinal Fusion.

PubMed

Barry, Jeffrey J; Sing, David C; Vail, Thomas P; Hansen, Erik N

2017-02-01

The coexistence of degenerative hip disease and spinal pathology is not uncommon with the number of surgical treatments performed for each condition increasing annually. The limited research available suggests spinal pathology portends less pain relief and worse outcomes after total hip arthroplasty (THA). We hypothesize that primary THA patients with preexisting lumbar spinal fusions (LSF) experience worse early postoperative outcomes. This study is a retrospective matched cohort study. Primary THA patients at 1 institution who had undergone prior LSF (spine arthrodesis-hip arthroplasty [SAHA]) were identified and matched to controls of primary THA without LSF. Early outcomes (<90 days) were compared. From 2012 to 2014, 35 SAHA patients were compared to 70 matched controls. Patients were similar in age, sex, American Society of Anesthesiologist score, body mass index, and Charlson Comorbidity Index. SAHA patients had higher rates of complications (31.4% vs 8.6%, P = .008), reoperation (14.3% vs 2.9%, P = .040), and general anesthesia (54.3% vs 5.7%, P = .0001). Bivariate analysis demonstrated SAHA to predict reoperation (odds ratio, 5.67; P = .045) and complications (odds ratio, 4.89; P = .005). With the numbers available, dislocations (0% vs 2.8%), infections (0% vs 8.6%), readmissions, postoperative walking distance, and disposition only trended to favor controls (P > .05). Comparing controls to SAHA patients with <3 or ≥3 levels fused, longer fusions had increased cumulative postoperative narcotic consumption (mean morphine equivalents, 44.3 vs 46.9 vs 169.4; P = .001). Patients with preexisting LSF experience worse early outcomes after primary THA including higher rates of complications and reoperation. Lower rates of neuraxial anesthesia and increased narcotic usage represent potential contributors. The complex interplay between the lumbar spine and hip warrants attention and further investigation. Copyright © 2016 Elsevier Inc. All rights reserved.

Statistical description of the motion of dislocation kinks in a random field of impurities adsorbed by a dislocation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petukhov, B. V., E-mail: petukhov@ns.crys.ras.r

2010-01-15

A model has been proposed for describing the influence of impurities adsorbed by dislocation cores on the mobility of dislocation kinks in materials with a high crystalline relief (Peierls barriers). The delay time spectrum of kinks at statistical fluctuations of the impurity density has been calculated for a sufficiently high energy of interaction between impurities and dislocations when the migration potential is not reduced to a random Gaussian potential. It has been shown that fluctuations in the impurity distribution substantially change the character of the migration of dislocation kinks due to the slow decrease in the probability of long delaymore » times. The dependences of the position of the boundary of the dynamic phase transition to a sublinear drift of kinks x {proportional_to} t{sup {delta}} ({delta} {sigma} 1) and the characteristics of the anomalous mobility on the physical parameters (stress, impurity concentration, experimental temperature, etc.) have been calculated.« less

Atomistically determined phase-field modeling of dislocation dissociation, stacking fault formation, dislocation slip, and reactions in fcc systems

NASA Astrophysics Data System (ADS)

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

Linear complexions: Confined chemical and structural states at dislocations

NASA Astrophysics Data System (ADS)

Kuzmina, M.; Herbig, M.; Ponge, D.; Sandlöbes, S.; Raabe, D.

2015-09-01

For 5000 years, metals have been mankind’s most essential materials owing to their ductility and strength. Linear defects called dislocations carry atomic shear steps, enabling their formability. We report chemical and structural states confined at dislocations. In a body-centered cubic Fe-9 atomic percent Mn alloy, we found Mn segregation at dislocation cores during heating, followed by formation of face-centered cubic regions but no further growth. The regions are in equilibrium with the matrix and remain confined to the dislocation cores with coherent interfaces. The phenomenon resembles interface-stabilized structural states called complexions. A cubic meter of strained alloy contains up to a light year of dislocation length, suggesting that linear complexions could provide opportunities to nanostructure alloys via segregation and confined structural states.

Scattering of phonons by dislocations

DOE Office of Scientific and Technical Information (OSTI.GOV)

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, andmore » 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/sup 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.« less

Long-term Outcome of Unconstrained Primary Total Hip Arthroplasty in Ipsilateral Residual Poliomyelitis.

PubMed

Buttaro, Martín A; Slullitel, Pablo A; García Mansilla, Agustín M; Carlucci, Sofía; Comba, Fernando M; Zanotti, Gerardo; Piccaluga, Francisco

2017-03-01

Incapacitating articular sequelae in the hip joint have been described for patients with late effects of poliomyelitis. In these patients, total hip arthroplasty (THA) has been associated with a substantial rate of dislocation. This study was conducted to evaluate the long-term clinical and radiologic outcomes of unconstrained THA in this specific group of patients. The study included 6 patients with ipsilateral polio who underwent primary THA between 1985 and 2006. Patients with polio who underwent THA on the nonparalytic limb were excluded. Mean follow-up was 119.5 months (minimum, 84 months). Clinical outcomes were evaluated with the modified Harris Hip Score (mHHS) and the visual analog scale (VAS) pain score. Radiographs were examined to identify the cause of complications and determine the need for revision surgery. All patients showed significantly better functional results when preoperative and postoperative mHHS (67.58 vs 87.33, respectively; P=.002) and VAS pain score (7.66 vs 2, respectively; P=.0003) were compared. Although 2 cases of instability were diagnosed, only 1 patient needed acetabular revision as a result of component malpositioning. None of the patients had component loosening, osteolysis, or infection. Unconstrained THA in the affected limb of patients with poliomyelitis showed favorable long-term clinical results, with improved function and pain relief. Nevertheless, instability may be a more frequent complication in this group of patients compared with the general population. [Orthopedics. 2017; 40(2):e255-e261.]. Copyright 2016, SLACK Incorporated.

Reliability and Validity of the Hip Stability Isometric Test (HipSIT): A New Method to Assess Hip Posterolateral Muscle Strength.

PubMed

Almeida, Gabriel Peixoto Leão; das Neves Rodrigues, Helena Larissa; de Freitas, Bruno Wesley; de Paula Lima, Pedro Olavo

2017-12-01

Study Design Cross-sectional study. Background The Hip Stability Isometric Test (HipSIT) evaluates the strength of the hip posterolateral stabilizers in a position that favors greater activation of the gluteus maximus and gluteus medius and lower activation of the tensor fascia lata. Objectives To check the validity and reliability of the HipSIT and to evaluate the HipSIT in women with patellofemoral pain (PFP). Methods The HipSIT was evaluated with a handheld dynamometer. During testing, the participants were sidelying, with their legs positioned at 45° of hip flexion and 90° of knee flexion. Participants were instructed to raise the knee of the upper leg while keeping the upper and lower heels in contact. To establish reliability and validity, 49 women were tested with the HipSIT by 2 different evaluators on day 1, and then again 7 days later. The strength of the hip extensors, abductors, and external rotators was also evaluated. Twenty women with unilateral PFP were also evaluated. Results The HipSIT has excellent intrarater and interrater reliability. The standard error of measurement was 0.01 kgf/kg, and the minimal detectable change was 0.036 kgf/kg. The HipSIT showed good validity in isolated hip abduction, external rotation, and extension (P<.01). Women with PFP showed a 10% deficit in the HipSIT results for the symptomatic limb (P = .01). Conclusion The HipSIT showed excellent interrater and intrarater reliability, moderate to good validity in women, and was able to identify strength deficits in women with PFP. J Orthop Sports Phys Ther 2017;47(12):906-913. Epub 9 Oct 2017. doi:10.2519/jospt.2017.7274.

Dislocation nucleation facilitated by atomic segregation

DOE PAGES

Zou, Lianfeng; Yang, Chaoming; Lei, Yinkai; ...

2017-11-27

Surface segregation—the enrichment of one element at the surface, relative to the bulk—is ubiquitous to multi-component materials. Using the example of a Cu–Au solid solution, we demonstrate that compositional variations induced by surface segregation are accompanied by misfit strain and the formation of dislocations in the subsurface region via a surface di˙usion and trapping process. The resulting chemically ordered surface regions acts as an e˙ective barrier that inhibits subsequent dislocation annihilation at free surfaces. Using dynamic, atomic-scale resolution electron microscopy observations and theory modelling, we show that the dislocations are highly active, and we delineate the specific atomic-scale mechanisms associatedmore » with their nucleation, glide, climb, and annihilation at elevated temperatures. As a result, these observations provide mechanistic detail of how dislocations nucleate and migrate at heterointerfaces in dissimilar-material systems.« less

[The Use of Jumbo Cups in Revision Total Hip Arthroplasty].

PubMed

von Roth, Philipp; Wassilew, Georgi I

2017-10-01

Extra-large uncemented jumbo cups are among the most common methods of acetabular revision. Jumbo cups do not contribute to bone stock restoration, and in the case of a subsequent revision, an even larger bone defect is to be expected. Thus, understanding long-term survival is essential. The present article discusses the literature relevant to this topic and addresses technical and implant-specific characteristics of jumbo cups. In summary, jumbo cups show an acceptable long-term survival rate, with aseptic loosening as the most common reason for revision and dislocation being the most common complication. Through the development of alternative revision systems, jumbo cups have lost their importance in today's practice. However, they can serve as a benchmark for studies of newer technologies in revision total hip arthroplasty. Georg Thieme Verlag KG Stuttgart · New York.

[Nuclear magnetic tomography in shoulder dislocation].

PubMed

Runkel, M; Kreitner, K F; Wenda, K; Rudig, L; Degreif, J; Grebe, P

1993-03-01

Sixty-two patients with anterior shoulder dislocations were examined by magnetic resonance imaging (MRI). After a primary dislocation, 30 patients showed 23 (77%) tears of the glenoid labrum, 13 (45%) anterior-inferior separation of the capsula, 24 (83%) Hill-Sachs lesions, 6 fractures of the greater tuberosity and 4 glenoid rim fractures. Thirty-two patients with recurrent shoulder dislocation had 14 (44%) tears and 15 (47%) defects of the glenoid labrum, 16 (50%) anterior-inferior separation of the capsula, 28 (88%) Hill-Sachs lesions and 3 glenoid rim fractures. MRI permits complete non-invasive documentation of glenohumeral instability if joint effusion is present. In the absence of joint effusion, diagnostic accuracy can be improved by application of a contrast medium.

Dislocation core structures of tungsten with dilute solute hydrogen

NASA Astrophysics Data System (ADS)

Wang, Yinan; Li, Qiulin; Li, Chengliang; Shu, Guogang; Xu, Ben; Liu, Wei

2017-12-01

In this paper, a combination of quantum mechanical and interatomic potential-based atomistic calculations are used to predict the core structures of screw and edge dislocations in tungsten in the presence of a particular concentration of hydrogen atoms. These configurations of the core structures are the results of two competing energies: the interaction between the partial dislocations and the corresponding generalized stacking fault energy in between the two partial dislocations, which are presented in this work. With this, we can precisely predict the configurations of the hydrogen-doped dislocation core structures.

The equivalence between dislocation pile-ups and cracks

NASA Technical Reports Server (NTRS)

Liu, H. W.; Gao, Q.

1990-01-01

Cracks and dislocation pile-ups are equivalent to each other. In this paper, the physical equivalence between cracks and pile-ups is delineated, and the relationshps between crack-extension force, force on the leading dislocation, stress-intensity factor, and dislocation density are reviewed and summarized. These relations make it possible to extend quantitatively the recent advances in the concepts and practices of fracture mechanics to the studies of microfractures and microplastic deformations.

Greater Trochanteric Fixation Using a Cable System for Partial Hip Arthroplasty: A Clinical and Finite Element Analysis

PubMed Central

Ozan, Fırat; Koyuncu, Şemmi; Pekedis, Mahmut; Altay, Taşkın; Yıldız, Hasan; Toker, Gökhan

2014-01-01

The aim of the study was to investigate the efficacy of greater trochanteric fixation using a multifilament cable to ensure abductor lever arm continuity in patients with a proximal femoral fracture undergoing partial hip arthroplasty. Mean age of the patients (12 men, 20 women) was 84.12 years. Mean follow-up was 13.06 months. Fixation of the dislocated greater trochanter with or without a cable following load application was assessed by finite element analysis (FEA). Radiological evaluation was based on the distance between the fracture and the union site. Harris hip score was used to evaluate final results: outcomes were excellent in 7 patients (21.8%), good in 17 patients (53.1%), average in 5 patients (15.6%), and poor in 1 patient (9.3%). Mean abduction angle was 20.21°. Union was achieved in 14 patients (43.7%), fibrous union in 12 (37.5%), and no union in 6 (18.7%). FEA showed that the maximum total displacement of the greater trochanter decreased when the fractured bone was fixed with a cable. As the force applied to the cable increased, the displacement of the fractured trochanter decreased. This technique ensures continuity of the abductor lever arm in patients with a proximal femoral fracture who are undergoing partial hip arthroplasty surgery. PMID:25177703

Similar range of motion and function after resurfacing large–head or standard total hip arthroplasty

PubMed Central

2013-01-01

Background and purpose Large–size hip articulations may improve range of motion (ROM) and function compared to a 28–mm THA, and the low risk of dislocation allows the patients more activity postoperatively. On the other hand, the greater extent of surgery for resurfacing hip arthroplasty (RHA) could impair rehabilitation. We investigated the effect of head size and surgical procedure on postoperative rehabilitation in a randomized clinical trial (RCT). Methods We followed randomized groups of RHAs, large–head THAs and standard THAs at 2 months, 6 months, 1 and 2 years postoperatively, recording clinical rehabilitation parameters. Results Large articulations increased the mean total range of motion by 13° during the first 6 postoperative months. The increase was not statistically significant and was transient. The 2–year total ROM (SD) for RHA, standard THA, and large–head THA was 221° (35), 232° (36), and 225° (30) respectively, but the differences were not statistically significant. The 3 groups were similar regarding Harris hip score, UCLA activity score, step rate, and sick leave. Interpretation Head size had no influence on range of motion. The lack of restriction allowed for large articulations did not improve the clinical and patient–perceived outcomes. The more extensive surgical procedure of RHA did not impair the rehabilitation. This project is registered at ClinicalTrials.gov under # NCT01113762. PMID:23530872

In-game Management of Common Joint Dislocations

PubMed Central

Skelley, Nathan W.; McCormick, Jeremy J.; Smith, Matthew V.

2014-01-01

Context: Sideline management of sports-related joint dislocations often places the treating medical professional in a challenging position. These injuries frequently require prompt evaluation, diagnosis, reduction, and postreduction management before they can be evaluated at a medical facility. Our objective is to review the mechanism, evaluation, reduction, and postreduction management of sports-related dislocations to the shoulder, elbow, finger, knee, patella, and ankle joints. Evidence Acquisition: A literature review was performed using the PubMed database to evaluate previous and current publications focused on joint dislocations. This review focused on articles published between 1980 and 2013. Study Design: Clinical review. Level of Evidence: Level 4. Results: The clinician should weigh the benefits and risks of on-field reduction based on their knowledge of the injury and the presence of associated injuries. Conclusion: When properly evaluated and diagnosed, most sports-related dislocations can be reduced and initially managed at the game. PMID:24790695

On damping of screw dislocation bending vibrations in dissipative crystal: limiting cases

NASA Astrophysics Data System (ADS)

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.

Actin binding by Hip1 (huntingtin-interacting protein 1) and Hip1R (Hip1-related protein) is regulated by clathrin light chain.

PubMed

Wilbur, Jeremy D; Chen, Chih-Ying; Manalo, Venus; Hwang, Peter K; Fletterick, Robert J; Brodsky, Frances M

2008-11-21

The huntingtin-interacting protein family members (Hip1 and Hip1R in mammals and Sla2p in yeast) link clathrin-mediated membrane traffic to actin cytoskeleton dynamics. Genetic data in yeast have implicated the light chain subunit of clathrin in regulating this link. To test this hypothesis, the biophysical properties of mammalian Hip1 and Hip1R and their interaction with clathrin light chain and actin were analyzed. The coiled-coil domains (clathrin light chain-binding) of Hip1 and Hip1R were found to be stable homodimers with no propensity to heterodimerize in vitro. Homodimers were also predominant in vivo, accounting for cellular segregation of Hip1 and Hip1R functions. Coiled-coil domains of Hip1 and Hip1R differed in their stability and flexibility, correlating with slightly different affinities for clathrin light chain and more markedly with effects of clathrin light chain binding on Hip protein-actin interactions. Clathrin light chain binding induced a compact conformation of both Hip1 and Hip1R and significantly reduced actin binding by their THATCH domains. Thus, clathrin is a negative regulator of Hip-actin interactions. These observations necessarily change models proposed for Hip protein function.

Bilateral Posterior Tibial Tendon and Flexor Digitorum Longus Dislocations.

PubMed

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.

Glide of threading edge dislocations after basal plane dislocation conversion during 4H-SiC epitaxial growth

NASA Astrophysics Data System (ADS)

Abadier, Mina; Song, Haizheng; Sudarshan, Tangali S.; Picard, Yoosuf N.; Skowronski, Marek

2015-05-01

Transmission electron microscopy (TEM) and KOH etching were used to analyze the motion of dislocations after the conversion of basal plane dislocations (BPDs) to threading edge dislocations (TEDs) during 4H-SiC epitaxy. The locations of TED etch pits on the epilayer surface were shifted compared to the original locations of BPD etch pits on the substrate surface. The shift of the TED etch pits was mostly along the BPD line directions towards the up-step direction. For converted screw type BPDs, the conversion points were located below the substrate/epilayer interface. The shift distances in the step-flow direction were proportional to the depths of the BPD-TED conversion points below the substrate/epilayer interface. For converted mixed type BPDs, the conversion points were exactly at the interface. Through TEM analysis, it was concluded that the dislocation shift is caused by a combined effect of H2 etching prior to growth and glide of the threading segments during high temperature epitaxy. The TED glide is only possible for converted pure screw type BPDs and could present a viable means for eliminating BPDs from the epilayer during growth by moving the conversion point below the substrate/epilayer interface.

An initial experience with hip resurfacing versus cementless total hip arthroplasty.

PubMed

Arndt, Justin Michael; Wera, Glenn D; Goldberg, Victor M

2013-07-01

Hip resurfacing is an alternative to total hip arthroplasty. We aimed to compare an experienced hip surgeon's initial clinical results of hip resurfacing with a new cementless total hip arthroplasty (THA). The first 55 consecutive hip resurfacing arthroplasties were compared to 100 consecutive cementless THAs using a cylindrical tapered femoral stem. The learning curve between the two procedures was compared utilizing the incidence of reoperation, complications, Harris Hip Scores (HHS), and implant survivorship. The reoperation rate was significantly higher (p = 0.019) for hip resurfacing (14.5%) versus THA (4%). The overall complication rate between the two groups was not significantly different (p = 0.398). Preoperative HHS were similar between the two groups (p = 0.2). The final mean HHS was similar in both the resurfacing and THA groups (96 vs. 98.3, respectively, p < 0.65). Kaplan-Meier survival analysis with an endpoint of reoperation suggests complications occurred earlier in the resurfacing group versus the THA group (log-rank test, p = 0.007). In comparison to our initial experience with a cementless THA stem, operative complications occur earlier and more often after hip resurfacing during the learning period. The clinical outcomes in both groups however are similar at 5 year follow-up.

Linear complexions: Confined chemical and structural states at dislocations.

PubMed

Kuzmina, M; Herbig, M; Ponge, D; Sandlöbes, S; Raabe, D

2015-09-04

For 5000 years, metals have been mankind's most essential materials owing to their ductility and strength. Linear defects called dislocations carry atomic shear steps, enabling their formability. We report chemical and structural states confined at dislocations. In a body-centered cubic Fe-9 atomic percent Mn alloy, we found Mn segregation at dislocation cores during heating, followed by formation of face-centered cubic regions but no further growth. The regions are in equilibrium with the matrix and remain confined to the dislocation cores with coherent interfaces. The phenomenon resembles interface-stabilized structural states called complexions. A cubic meter of strained alloy contains up to a light year of dislocation length, suggesting that linear complexions could provide opportunities to nanostructure alloys via segregation and confined structural states. Copyright © 2015, American Association for the Advancement of Science.

Gluteal tendinopathy and hip osteoarthritis: Different pathologies, different hip biomechanics.

PubMed

Allison, Kim; Hall, Michelle; Hodges, Paul W; Wrigley, Tim V; Vicenzino, Bill; Pua, Yong-Hao; Metcalf, Ben; Grimaldi, Alison; Bennell, Kim L

2018-03-01

Gluteal tendinopathy (GT) and hip osteoarthritis (OA) are the most common causes of hip pain and associated disability in older adults. Pain and altered walking biomechanics are common to both conditions. This study aimed to compare three-dimensional walking biomechanics between individuals with unilateral, symptomatic GT and HOA. Sixty individuals with symptomatic unilateral GT confirmed by magnetic-resonance-imaging and 73 individuals with symptomatic unilateral HOA (Kellgren-Lawrence Grade ≥ 2) underwent three-dimensional gait analysis. Maximum and minimum values of the external sagittal hip moment, the first peak, second peak and mid-stance minimum of the hip adduction moment (HAM), sagittal plane hip excursion and hip joint angles, pelvic obliquity and trunk lean, at the three HAM time points during stance phase of walking were compared between groups. Compared to individuals with HOA, those with GT exhibited a greater hip peak extension moment (P < 0.001) and greater HAM throughout the stance phase of walking (P = 0.01-P < 0.001), greater hip adduction (P < 0.001) and internal rotation (P < 0.01-P < 0.001) angles and lower hip flexion angles and excursion (P = 0.02 - P < 0.001). Individuals with HOA exhibited a greater forward trunk lean (P ≤ 0.001) throughout stance, and greater ipsilateral trunk lean in the frontal plane (P < 0.001) than those with GT. Despite presence of pain in both conditions, hip kinematics and kinetics differ between individuals with symptomatic unilateral GT and those with symptomatic unilateral HOA. These condition-specific impairments may be targets for optimization of management of HOA and GT. Copyright © 2018 Elsevier B.V. All rights reserved.

Management of traumatic patellar dislocation in a regional hospital in Hong Kong.

PubMed

Lee, H L; Yau, W P

2017-04-01

The role of surgery for acute patellar dislocation without osteochondral fracture is controversial. The aim of this study was to report the short-term results of management of patellar dislocation in our institute. Patients who were seen in our institution with patella dislocation from January 2011 to April 2014 were managed according to a standardised management algorithm. Pretreatment and 1-year post-treatment International Knee Documentation Committee score, Tegner activity level scale score, and presence of apprehension sign were analysed. A total of 41 patients were studied of whom 20 were first-time dislocators and 21 were recurrent dislocators. Among the first-time dislocators, there was a significant difference between patients who received conservative treatment versus surgical management. The conservative treatment group had a 33% recurrent dislocation rate, whereas there were no recurrent dislocations in the surgery group. There was no difference in Tegner activity level scale score or apprehension sign before and 1 year after treatment, however. Among the recurrent dislocators, there was a significant difference between those who received conservative treatment and those who underwent surgery. The recurrent dislocation rate was 71% in the conservative treatment group versus 0% in the surgery group. There was also significant improvement in International Knee Documentation Committee score from 67.7 to 80.0 (P=0.02), and of apprehension sign from 62% to 0% (P<0.01). A management algorithm for patellar dislocation is described. Surgery is preferable to conservative treatment in patients who have recurrent patellar dislocation, and may also be preferable for those who have an acute dislocation.

Comparison of outcome measures and complication rates following three different approaches for primary total hip arthroplasty: a pragmatic randomised controlled trial.

PubMed

Talia, Adrian J; Coetzee, Cassandra; Tirosh, Oren; Tran, Phong

2018-01-08

Total hip arthroplasty is one of the most commonly performed surgical procedures worldwide. There are a number of surgical approaches for total hip arthroplasty and no high-level evidence supporting one approach over the other. Each approach has its unique benefits and drawbacks. This trial aims to directly compare the three most common surgical approaches for total hip arthroplasty. This is a single-centre study conducted at Western Health, Melbourne, Australia; a large metropolitan centre. It is a pragmatic, parallel three-arm, randomised controlled trial. Sample size will be 243 participants (81 in each group). Randomisation will be secure, web-based and managed by an independent statistician. Patients and research team will be blinded pre-operatively, but not post-operatively. Intervention will be either direct anterior, lateral or posterior approach for total hip arthroplasty, and the three arms will be directly compared. Participants will be aged over 18 years, able to provide informed consent and recruited from our outpatients. Patients who are having revision surgery or have indications for hip replacement other than osteoarthritis (i.e., fracture, malignancy, development dysplasia) will be excluded from the trial. The Oxford Hip Score will be determined for patients pre-operatively and 6 weeks, 6, 12 and 24 months post-operatively. The Oxford Hip Score at 24 months will be the primary outcome measure. Secondary outcome measures will be dislocation, infection, intraoperative and peri-prosthetic fracture rate, length of hospital stay and pain level, reported using a visual analogue scale. Many studies have evaluated approaches for total hip arthroplasty and arthroplasty registries worldwide are now collecting this data. However no study to date has compared these three common approaches directly in a randomised fashion. No trial has used patient-reported outcome measures to evaluate success. This pragmatic study aims to identify differences in patient

Diagnosis of Ehlers-Danlos syndrome after a first shoulder dislocation.

PubMed

Nourissat, Geoffroy; Vigan, Marie; Hamonet, Claude; Doursounian, Levon; Deranlot, Julien

2018-01-01

Shoulder dislocation is often the first symptom of Ehlers-Danlos syndrome (EDS). Whether it occurs in early-onset EDS is unknown. In most cases, surgical failure leads to the diagnosis. We aimed to determine whether clinical symptoms can signal the presence of EDS at a first dislocation. In this retrospective study, we analyzed clinical and radiologic data for 27 patients with EDS and shoulder instability and a control population of 40 consecutive non-EDS patients undergoing surgery for an unstable shoulder. Data were collected on gender, age, single or bilateral disease, general hyperlaxity, shoulder hyperlaxity, number of dislocations or subluxations, nontraumatic onset, and pain specificity. Nerve and vascular injuries, joint disorders, and family history were recorded, and radiologic data were reported. Age <14 years, female sex, bilateral disorder, and general hyperlaxity were significantly more frequent in patients with EDS and a first dislocation than in those without EDS. Painless dislocation with pain after dislocation and concomitant nerve injury were more frequent in affected patients, as were hemostasis disorders and a family history of joint hyperlaxity. Bone lesions were not seen on radiographs. Only the hyperlaxity sign (external rotation >85°) did not differ between the groups. After a first dislocation in a young girl with global hyperlaxity but not necessarily shoulder hyperlaxity, painless atraumatic dislocation with pain after reduction can suggest EDS. Copyright © 2018. Published by Elsevier Inc.

Total hip arthroplasty of dysplastic hip after previous Chiari pelvic osteotomy.

PubMed

Minoda, Yukihide; Kadowaki, Toru; Kim, Mitsunari

2006-08-01

Many reports have suggested that Chiari pelvic osteotomy would improve the results of acetabular component placement and fixation in subsequent total hip arthroplasty. However, little is known concerning the biomechanical, radiological, and clinical effects of Chiari pelvic osteotomy on subsequent total hip arthroplasty. Ten total hip arthroplasties for developmental dysplasia of the hip after previous Chiari pelvic osteotomy (Chiari group) were compared with 20 total hip arthroplasties for developmental dysplasia of the hip without previous surgery (control group). Preoperative patient demographic data and operative technique were well matched between the groups. The mean duration of follow-up was 3.0 years. Biomechanical, radiological, and clinical evaluations were performed. No acetabular or femoral components exhibited loosening. All patients had good or excellent clinical score according to the Merle d'Aubigne-Postel rating system at the most recent follow-up. Abductor force and joint force were smaller in the Chiari group, although long operative time, more blood loss, and verticalization of joint force were noted in this group. This limited study suggested that Chiari pelvic osteotomy changed the biomechanical features of the hip joint, and that this alteration might have compromised subsequent total hip arthroplasty.

Application of individually performed acrylic cement spacers containing 5% of antibiotic in two-stage revision of hip and knee prosthesis due to infection.

PubMed

Babiak, Ireneusz

2012-07-03

Deep infection of a joint endoprosthesis constitutes a threat to the stability of the implant and joint function. It requires a comprehensive and interdisciplinary approach, involving the joint revision and removal of the bacterial biofilm from all tissues, the endoprosthesis must be often removed and bone stock infection treated. The paper presents the author's experience with the use of acrylic cement spacers, custom-made during the surgery and containing low dose of an antibiotic supplemented with 5% of a selected, targeted antibiotic for the infection of hip and knee endoprostheses. 33 two-stage revisions of knee and hip joints with the use of a spacer were performed. They involved 24 knee joints and 9 hip joints. The infections were mostly caused by staphylococci MRSA (18) and MSSA (8), and in some cases Enterococci (4), Salmonella (1), Pseudomonas (1) and Acinetobacter (1). The infection was successfully treated in 31 out of 33 cases (93.93%), including 8 patients with the hip infection and 23 patients with the knee infection. The endoprosthesis was reimplanted in 30 cases: for 7 hips and 23 knees, in 3 remaining cases the endoprosthesis was not reimplanted. Mechanical complications due to the spacer occurred in 4 cases: 3 dislocations and 1 fracture (hip spacer). The patients with hip spacers were ambulatory with a partial weight bearing of the operated extremity and those with knee spacers were also ambulatory with a partial weight bearing, but the extremity was initially protected by an orthosis. The spacer enables to maintain a limb function, and making it by hand allows the addition of the specific bacteria targeted antibiotic thus increasing the likelihood of the effective antibacterial treatment.

Patellofemoral Arthritis After Lateral Patellar Dislocation: A Matched Population-Based Analysis.

PubMed

Sanders, Thomas L; Pareek, Ayoosh; Johnson, Nicholas R; Stuart, Michael J; Dahm, Diane L; Krych, Aaron J

2017-04-01

The rate of patellofemoral arthritis after lateral patellar dislocation is unknown. Purpose/Hypothesis: The purpose of this study was to compare the risk of patellofemoral arthritis and knee arthroplasty between patients who experienced a lateral patellar dislocation and matched individuals without a patellar dislocation. Additionally, factors predictive of arthritis after patellar dislocation were examined. The hypothesis was that the rate of arthritis is likely higher among patients who experience a patellar dislocation compared with those who do not. Cohort study; Level of evidence, 3. In this study, 609 patients who had a first-time lateral patellar dislocation between 1990 and 2010 were compared with an age- and sex-matched cohort of patients who did not have a patellar dislocation. Medical records were reviewed to collect information related to the initial injury, recurrent dislocation, treatment, and progression to clinically significant patellofemoral arthritis (defined as symptoms with degenerative changes on patellar sunrise radiographs). Factors associated with arthritis (age, sex, recurrence, osteochondral injury, trochlear dysplasia) were examined. At a mean follow-up of 12.3 ± 6.5 years from initial dislocation, 58 patients (9.5%) in the dislocation cohort were diagnosed with patellofemoral arthritis, corresponding to a cumulative incidence of arthritis of 1.2% at 5 years, 2.7% at 10 years, 8.1% at 15 years, 14.8% at 20 years, and 48.9% at 25 years. In the control cohort, 8 patients (1.3%) were diagnosed with arthritis, corresponding to a cumulative incidence of arthritis of 0% at 5 years, 0% at 10 years, 1.3% at 15 years, 2.9% at 20 years, and 8.3% at 25 years. Therefore, patients who experienced a lateral patellar dislocation had a significantly higher risk of developing arthritis (hazard ratio [HR], 7.8; 95% CI, 3.9-17.6; P < .001) than individuals without a patellar dislocation. However, the risk of knee arthroplasty was similar between groups

Transition of dislocation glide to shear transformation in shocked tantalum

DOE PAGES

Hsiung, Luke L.; Campbell, Geoffrey H.

2017-02-28

A TEM study of pure tantalum and tantalum-tungsten alloys explosively shocked at a peak pressure of 30 GPa (strain rate: ~1 x 10 4 sec -1) is presented. While no ω (hexagonal) phase was found in shock-recovered pure Ta and Ta-5W that contain mainly a low-energy cellular dislocation structure, shock-induced ω phase was found to form in Ta-10W that contains evenly distributed dislocations with a stored dislocation density higher than 1 x 10 12 cm -2. The TEM results clearly reveal that shock-induced α (bcc) → ω (hexagonal) shear transformation occurs when dynamic recovery reactions which lead the formation low-energymore » cellular dislocation structure become largely suppressed in Ta-10W shocked under dynamic (i.e., high strain-rate and high-pressure) conditions. A novel dislocation-based mechanism is proposed to rationalize the transition of dislocation glide to twinning and/or shear transformation in shock-deformed tantalum. Lastly, twinning and/or shear transformation take place as an alternative deformation mechanism to accommodate high-strain-rate straining when the shear stress required for dislocation multiplication exceeds the threshold shear stresses for twinning and/or shear transformation.« less

Actin Binding by Hip1 (Huntingtin-interacting Protein 1) and Hip1R (Hip1-related Protein) Is Regulated by Clathrin Light Chain*S⃞

PubMed Central

Wilbur, Jeremy D.; Chen, Chih-Ying; Manalo, Venus; Hwang, Peter K.; Fletterick, Robert J.; Brodsky, Frances M.

2008-01-01

The huntingtin-interacting protein family members (Hip1 and Hip1R in mammals and Sla2p in yeast) link clathrin-mediated membrane traffic to actin cytoskeleton dynamics. Genetic data in yeast have implicated the light chain subunit of clathrin in regulating this link. To test this hypothesis, the biophysical properties of mammalian Hip1 and Hip1R and their interaction with clathrin light chain and actin were analyzed. The coiled-coil domains (clathrin light chain-binding) of Hip1 and Hip1R were found to be stable homodimers with no propensity to heterodimerize in vitro. Homodimers were also predominant in vivo, accounting for cellular segregation of Hip1 and Hip1R functions. Coiled-coil domains of Hip1 and Hip1R differed in their stability and flexibility, correlating with slightly different affinities for clathrin light chain and more markedly with effects of clathrin light chain binding on Hip protein-actin interactions. Clathrin light chain binding induced a compact conformation of both Hip1 and Hip1R and significantly reduced actin binding by their THATCH domains. Thus, clathrin is a negative regulator of Hip-actin interactions. These observations necessarily change models proposed for Hip protein function. PMID:18790740

Computational issues in the simulation of two-dimensional discrete dislocation mechanics

NASA Astrophysics Data System (ADS)

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.

PubMed

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.

Grain size effects on dislocation and twinning mediated plasticity in magnesium

DOE PAGES

Fan, Haidong; Aubry, Sylvie; Arsenlis, Athanasios; ...

2015-09-20

Grain size effects on the competition between dislocation slip and {101¯2} -twinning in magnesium are investigated using discrete dislocation dynamics simulations. These simulations account for dislocation–twin boundary interactions and twin boundary migration through the glide of twinning dislocations. It is shown that twinning deformation exhibits a strong grain size effect; while dislocation mediated slip in untwinned polycrystals displays a weak one. In conclusion, this leads to a critical grain size at 2.7 μm, above which twinning dominates, and below which dislocation slip dominates.

Management of acute anterior shoulder dislocation.

PubMed

Dala-Ali, Benan; Penna, Marta; McConnell, Jamie; Vanhegan, Ivor; Cobiella, Carlos

2014-08-01

Shoulder dislocation is the most common large joint dislocation in the body. Recent advances in radiological imaging and shoulder surgery have shown the potential dangers of traditional reduction techniques such as the Kocher's and the Hippocratic methods, which are still advocated by many textbooks. Many non-specialists continue to use these techniques, unaware of their potential risks. This article reviews the clinical and radiographic presentation of dislocation; some common reduction techniques; their risks and success rate; analgesia methods to facilitate the reduction; and postreduction management. Many textbooks advocate methods that have been superceded by safer alternatives. Trainees should learn better and safer relocation methods backed up by the current evidence available. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Hip Resurfacing: An Alternative to Conventional Hip Replacement?

MedlinePlus

... and capped with a metal prosthesis. The hip socket is fitted with a metal cup. As these ... problem, but higher levels may be problematic. The socket prosthesis for a traditional hip replacement is usually ...

First-time anterior shoulder dislocations: should they be arthroscopically stabilised?

PubMed Central

Sedeek, Sedeek Mohamed; Bin Abd Razak, Hamid Rahmatullah; Ee, Gerard WW; Tan, Andrew HC

2014-01-01

The glenohumeral joint is inherently unstable because the large humeral head articulates with the small shadow glenoid fossa. Traumatic anterior dislocation of the shoulder is a relatively common athletic injury, and the high frequency of recurrent instability in young athletes after shoulder dislocation is discouraging to both the patient and the treating physician. Management of primary traumatic shoulder dislocation remains controversial. Traditionally, treatment involves initial immobilisation for 4–6 weeks, followed by functional rehabilitation. However, in view of the high recurrence rates associated with this traditional approach, there has been an escalating interest in determining whether immediate surgical intervention can lower the rate of recurrent shoulder dislocation, improving the patient’s quality of life. This review article aims to provide an overview of the nature and pathogenesis of first-time primary anterior shoulder dislocations, the widely accepted management modalities, and the efficacy of primary surgical intervention in first-time primary anterior shoulder dislocations. PMID:25631890

Prediction of dislocation generation during Bridgman growth of GaAs crystals

NASA Technical Reports Server (NTRS)

Tsai, C. T.; Yao, M. W.; Chait, Arnon

1992-01-01

Dislocation densities are generated in GaAs single crystals due to the excessive thermal stresses induced by temperature variations during growth. A viscoplastic material model for GaAs, which takes into account the movement and multiplication of dislocations in the plastic deformation, is developed according to Haasen's theory. The dislocation density is expressed as an internal state variable in this dynamic viscoplastic model. The deformation process is a nonlinear function of stress, strain rate, dislocation density and temperature. The dislocation density in the GaAs crystal during vertical Bridgman growth is calculated using a nonlinear finite element model. The dislocation multiplication in GaAs crystals for several temperature fields obtained from thermal modeling of both the GTE GaAs experimental data and artificially designed data are investigated.

Prediction of dislocation generation during Bridgman growth of GaAs crystals

NASA Astrophysics Data System (ADS)

Tsai, C. T.; Yao, M. W.; Chait, Arnon

1992-11-01

Dislocation densities are generated in GaAs single crystals due to the excessive thermal stresses induced by temperature variations during growth. A viscoplastic material model for GaAs, which takes into account the movement and multiplication of dislocations in the plastic deformation, is developed according to Haasen's theory. The dislocation density is expressed as an internal state variable in this dynamic viscoplastic model. The deformation process is a nonlinear function of stress, strain rate, dislocation density and temperature. The dislocation density in the GaAs crystal during vertical Bridgman growth is calculated using a nonlinear finite element model. The dislocation multiplication in GaAs crystals for several temperature fields obtained from thermal modeling of both the GTE GaAs experimental data and artificially designed data are investigated.

Crack Tip Dislocation Nucleation in FCC Solids

NASA Astrophysics Data System (ADS)

Knap, J.; Sieradzki, K.

1999-02-01

We present results of molecular dynamic simulations aimed at examining crack tip dislocation emission in fcc solids. The results are analyzed in terms of recent continuum formulations of this problem. In mode II, Au, Pd, and Pt displayed a new unanticipated mechanism of crack tip dislocation emission involving the creation of a pair of Shockley partials on a slip plane one plane below the crack plane. In mode I, for all the materials examined, Rice's continuum formulation [J. Mech. Phys. Solids 40, 239 (1992)] underestimated the stress intensity for dislocation emission by almost a factor of 2. Surface stress corrections to the emission criterion brought the agreement between continuum predictions and simulations to within 20%.

New method for revealing dislocations in garnet: premelting decoration

NASA Astrophysics Data System (ADS)

Liu, Xiangwen; Xie, Zhanjun; Jin, Zhenmin; Li, Zhuoyue; Ao, Ping; Wu, Yikun

2018-05-01

Premelting decoration (PMD) of dislocation experiments was carried out on garnets at 1 atmosphere pressure and temperatures of 800-1000 °C. Numerous decorated lines were observed on the polished surface of heat-treated garnet grains. The results of scanning electron microscopy, laser Raman spectroscopy and transmission electron microscopy (TEM) analyses indicate that these decorated lines were generated by premelting reaction along the dislocation lines and subgrain boundaries. The constituents of decorated lines on the polished surface of garnet are hematite, magnetite, and melt. While, in the interior of garnet, their constituents changed to Al-bearing magnetite and melt. The dislocation density of a gem-quality megacrystal garnet grain by means of the PMD is similar to that obtained by TEM, which confirms that the PMD is a new reliable method for revealing dislocations in garnet. This method greatly reduces the cost and time involved in the observation of dislocation microstructures in deformed garnet.

Modeling of dislocation channel width evolution in irradiated metals

NASA Astrophysics Data System (ADS)

Doyle, Peter J.; Benensky, Kelsa M.; Zinkle, Steven J.

2018-02-01

Defect-free dislocation channel formation has been reported to promote plastic instability during tensile testing via localized plastic flow, leading to a distinct loss of ductility and strain hardening in many low-temperature irradiated materials. In order to study the underlying mechanisms governing dislocation channel width and formation, the channel formation process is modeled via a simple stochastic dislocation-jog process dependent upon grain size, defect cluster density, and defect size. Dislocations traverse a field of defect clusters and jog stochastically upon defect interaction, forming channels of low defect-density. Based upon prior molecular dynamics (MD) simulations and in-situ experimental transmission electron microscopy (TEM) observations, each dislocation encounter with a dislocation loop or stacking fault tetrahedron (SFT) is assumed to cause complete absorption of the defect cluster, prompting the dislocation to jog up or down by a distance equal to half the defect cluster diameter. Channels are predicted to form rapidly and are comparable to reported TEM measurements for many materials. Predicted channel widths are found to be most strongly dependent on mean defect size and correlated well with a power law dependence on defect diameter and density, and distance from the dislocation source. Due to the dependence of modeled channel width on defect diameter and density, maximum channel width is predicted to slowly increase as accumulated dose increases. The relatively weak predicted dependence of channel formation width with distance, in accordance with a diffusion analogy, implies that after only a few microns from the source, most channels observed via TEM analyses may not appear to vary with distance because of limitations in the field-of-view to a few microns. Further, examinations of the effect of the so-called "source-broadening" mechanism of channel formation showed that its effect is simply to add a minimum thickness to the channel

[Revision hip arthroplasty by Waldemar Link custom-made total hip prosthesis].

PubMed

Medenica, Ivica; Luković, Milan; Radoicić, Dragan

2010-02-01

The number of patients undergoing hip arthroplasty revision is constantly growing. Especially, complex problem is extensive loss of bone stock and pelvic discontinuity that requires reconstruction. The paper presented a 50-year old patient, who ten years ago underwent a total cement artrhroplasty of the left hip. A year after the primary operation the patient had difficulties in walking without crutches. Problems intensified in the last five years, the patient had severe pain, totally limited movement in the left hip and could not walk at all. Radiographically, we found loose femoral component, massive loss of bone stock of proximal femur, acetabular protrusion and a consequent pelvic discontinuity. Clinically, a completely disfunctional left hip joint was registered (Harris hip score--7.1). We performed total rearthroplasty by a custom-made Waldemar Link total hip prosthesis with acetabular antiprotrusio cage and compensation of bone defects with a graft from the bone bank. A year after the operation, we found clinically an extreme improvement in Harris hip score--87.8. Radiographically, we found stability of implanted components, a complete graft integration and bone bridging across the site of pelvic discontinuity. Pelvic discontinuity and massive loss of proximal femoral bone stock is a challenging and complex entity. Conventional prostheses cannot provide an adequate fixation and stability of the hip. Application of custom-made prosthesis (measured specificaly for a patient) and additional alografting bone defects is a good method in revision surgery after unsuccessful hip arthroplasty with extensive bone defects.

[The role of exogenous factors in the etiology of congenital hip dislocation: a socio-epidemiologic study].

PubMed

Drimal, J

1989-10-01

The authors present in their work the results of the analysis of the relation between congenital dislocation of vertebral joints and social factors which they have found out in 120 children singled out of 9516 live-born children in the Martin district (Slovakia) in the period 1979-1983. The investigation of social factors has been based on the analysis of socioeconomic and social conditions of the Martin district which has no regional particularities. According to their results the share of exogenous factors in the origin and development of this disease is manifested more frequently in the first-borns (having the highest representation in the examined group). On the top of the list of social indices, which they have examined in primiparae and multiparae respectively, there are unsuitable housing conditions (living in discord with mother-in-law in the same house-hold), high percentage of impregnation before marriage which can be considered a strain and longterm conflicting situation and can have together with other factors a sociopathogenetic effect.

Primary total hip replacement versus hip resurfacing - hospital considerations.

PubMed

Ward, William G; Carter, Christina J; Barone, Marisa; Jinnah, Riyaz

2011-01-01

Multiple factors regarding surgical procedures and patient selection affect hospital staffing needs as well as hospital revenues. In order to better understand the potential impact on hospitals that hip arthroplasty device selection (standard total hip arthroplasty vs. resurfacing) creates, a review of all primary hip arthroplasties performed at one institution was designed to identify factors that impacted hospital staffing needs and revenue generation. All primary hip arthroplasties undertaken over three fiscal years (2008 to 2010) were reviewed, utilizing only hospital business office data and medical records data that had been previously extracted prior for billing purposes. Analysis confirmed differing demographics for two hip arthroplasty populations, with the resurfacing patients (compared to the conventional total hip arthroplasty population) consisting of younger patients (mean age, 50 vs. 61 years), who were more often male (75% vs. 45%), were more likely to have osteoarthritis as their primary diagnosis (83 vs. 67%) and were more often covered by managed care or commercial insurance (83 vs. 34%). They also had shorter hospital stays (mean length of stay, 2.3 vs. 4.1 days) and consequently provided a more favorable financial revenue stream to the hospital on a per patient basis. Several trends appeared during the study periods. There was a steady increase in all procedures in all groups except for the resurfacings, which decreased 26% in males and 53% in females between 2009 and 2010. Differences were observed in the demographics of patients presenting for resurfacing, compared to those presenting for conventional total hip arthroplasty. In addition to the revenue stream considerations, institutions undertaking a resurfacing program must commit the resources and planning in order to rehabilitate these patients more expeditiously than is usually required with conventional hip arthroplasty patients.

Simultaneous dislocation of the metacarpophalangeal and interphalangeal joints of the thumb.

PubMed

Tabib, William; Sayegh, Samir

2002-01-01

Combined dislocation of the metacarpophalangeal and interphalangeal joints of the thumb is uncommon. We know of only four previously reported cases. We report a new case characterised by dorsal dislocation of both joints. Because of entrapment of the volar plate, open reduction at the interphalangeal joint was necessary. The metacarpophalangeal dislocation was treated by closed reduction. After three weeks of immobilisation, physiotherapy resulted in a satisfactory outcome. Even if the diagnosis of dislocation of the interphalangeal joint is obvious it would be easy to overlook a simultaneous dislocation of the metacarpophalangeal joint with serious consequences. Whole hand examination remains an essential rule.

Chronological changes in functional cup position at 10 years after total hip arthroplasty.

PubMed

Okanoue, Yusuke; Ikeuchi, Masahiko; Takaya, Shogo; Izumi, Masashi; Aso, Koji; Kawakami, Teruhiko

2017-09-19

This study aims to clarify the chronological changes in functional cup position at a minimum follow-up of 10 years after total hip arthroplasty (THA), and to identify the risk factors influencing a significant difference in functional cup position during the postoperative follow-up period. We evaluated the chronological changes in functional cup position at a minimum follow-up of 10 years after THA in 58 patients with unilateral hip osteoarthritis. Radiographic cup position was measured on anteroposterior pelvic radiographs with the patient in the supine position, whereas functional cup position was recorded in the standing position. Radiographs were obtained before, 3 weeks after, and every 1 year after surgery. Functional cup anteversion (F-Ant) increased over time, and was found to have significantly increased at final follow-up compared to that at 3 weeks after surgery (p<0.01). The maximum postoperative change in F-Ant was 17.0° anteriorly; 12 cases (21%) showed a postoperative change in F-Ant by >10° anteriorly. Preoperative posterior pelvic tilt in the standing position and vertebral fractures after THA were significant predictors of increasing functional cup anteversion. Although chronological changes in functional cup position do occur after THA, their magnitude is relatively low. However, posterior impingement is likely to occur, which may cause edge loading, wear of the polyethylene liner, and anterior dislocation of the hip. We believe that, for the combined anteversion technique, the safe zone should probably be 5°-10° narrower in patients predicted to show considerable changes in functional cup position compared with standard cases.

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

PubMed Central

2011-01-01

Background 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. Method and materials 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. Result 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. Conclusion 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. PMID:21676208

Sex differences of hip morphology in young adults with hip pain and labral tears.

PubMed

Hetsroni, Iftach; Dela Torre, Katrina; Duke, Gavin; Lyman, Stephen; Kelly, Bryan T

2013-01-01

To compare hip morphology between young men and women who presented with hip pain and labral tears. A retrospective review of our hip arthroscopy registry from March 2008 to June 2010 was completed. We identified 217 patients (249 hips) who were between the ages of 18 to 30 years. The inclusion criteria were (1) insidious-onset hip pain or worsening pain after low-energy sports trauma, (2) positive hip impingement sign, (3) Tönnis grades 0 to 1, (4) magnetic resonance imaging showing labral tear, and (5) primary hip arthroscopy confirming labral tear. Forty-five patients (52 hips) were excluded for the following reasons: (1) revision hip arthroscopy, (2) high-energy hip trauma, (3) history of surgery involving the femur or pelvis, (4) previous fractures of the femur or pelvis, (5) Tönnis grades 2 or above, (6) proliferative disease of the hip (i.e., synovial chondromatosis, pigmented villonodular synovitis), (7) neuromuscular disease (i.e., cerebral palsy), and (8) deformities related to Legg-Calvé-Perthes disease or developmental dysplasia of the hip. Therefore, the cohort study group included 105 (61%) men (123 [62.4%] hips) and 67 (39%) women (74 [37.6%] hips). Sex comparisons were made for the following variables measured on preoperative hip computed tomography scans: alpha angle, acetabular version, femoral version, lateral center-edge angle, and neck-shaft angle. Women had smaller alpha angles (47.8°v 63.6°, P < .001), increased acetabular version (17.3°v 13.9°, P < .001), and increased femoral anteversion (14.4°v 12.1°, P = .05). In young adults with hip pain and labral tears, women have smaller alpha angles and hips that are generally more anteverted. Therefore, in women, cam lesions may be more subtle, preoperative hip version analyses should be encouraged, and rim trimming may need to be cautiously planned to avoid increasing contact stresses at weight-bearing areas after such a procedure. Level III, retrospective comparative study. Copyright �

Dislocation Strengthening without Ductility Trade-off in Metastable Austenitic Steels

PubMed Central

Liu, Jiabin; Jin, Yongbin; Fang, Xiaoyang; Chen, Chenxu; Feng, Qiong; Liu, Xiaowei; Chen, Yuzeng; Suo, Tao; Zhao, Feng; Huang, Tianlin; Wang, Hongtao; Wang, Xi; Fang, Youtong; Wei, Yujie; Meng, Liang; Lu, Jian; Yang, Wei

2016-01-01

Strength and ductility are mutually exclusive if they are manifested as consequence of the coupling between strengthening and toughening mechanisms. One notable example is dislocation strengthening in metals, which invariably leads to reduced ductility. However, this trend is averted in metastable austenitic steels. A one-step thermal mechanical treatment (TMT), i.e. hot rolling, can effectively enhance the yielding strength of the metastable austenitic steel from 322 ± 18 MPa to 675 ± 15 MPa, while retaining both the formability and hardenability. It is noted that no boundaries are introduced in the optimized TMT process and all strengthening effect originates from dislocations with inherited thermal stability. The success of this method relies on the decoupled strengthening and toughening mechanisms in metastable austenitic steels, in which yield strength is controlled by initial dislocation density while ductility is retained by the capability to nucleate new dislocations to carry plastic deformation. Especially, the simplicity in processing enables scaling and industrial applications to meet the challenging requirements of emissions reduction. On the other hand, the complexity in the underlying mechanism of dislocation strengthening in this case may shed light on a different route of material strengthening by stimulating dislocation activities, rather than impeding motion of dislocations. PMID:27739481

Dislocation Strengthening without Ductility Trade-off in Metastable Austenitic Steels

NASA Astrophysics Data System (ADS)

Liu, Jiabin; Jin, Yongbin; Fang, Xiaoyang; Chen, Chenxu; Feng, Qiong; Liu, Xiaowei; Chen, Yuzeng; Suo, Tao; Zhao, Feng; Huang, Tianlin; Wang, Hongtao; Wang, Xi; Fang, Youtong; Wei, Yujie; Meng, Liang; Lu, Jian; Yang, Wei

2016-10-01

Strength and ductility are mutually exclusive if they are manifested as consequence of the coupling between strengthening and toughening mechanisms. One notable example is dislocation strengthening in metals, which invariably leads to reduced ductility. However, this trend is averted in metastable austenitic steels. A one-step thermal mechanical treatment (TMT), i.e. hot rolling, can effectively enhance the yielding strength of the metastable austenitic steel from 322 ± 18 MPa to 675 ± 15 MPa, while retaining both the formability and hardenability. It is noted that no boundaries are introduced in the optimized TMT process and all strengthening effect originates from dislocations with inherited thermal stability. The success of this method relies on the decoupled strengthening and toughening mechanisms in metastable austenitic steels, in which yield strength is controlled by initial dislocation density while ductility is retained by the capability to nucleate new dislocations to carry plastic deformation. Especially, the simplicity in processing enables scaling and industrial applications to meet the challenging requirements of emissions reduction. On the other hand, the complexity in the underlying mechanism of dislocation strengthening in this case may shed light on a different route of material strengthening by stimulating dislocation activities, rather than impeding motion of dislocations.

Controllable Growth and Formation Mechanisms of Dislocated WS2 Spirals.

PubMed

Fan, Xiaopeng; Zhao, Yuzhou; Zheng, Weihao; Li, Honglai; Wu, Xueping; Hu, Xuelu; Zhang, Xuehong; Zhu, Xiaoli; Zhang, Qinglin; Wang, Xiao; Yang, Bin; Chen, Jianghua; Jin, Song; Pan, Anlian

2018-06-13

Two-dimensional (2D) layered metal dichalcogenides can form spiral nanostructures by a screw-dislocation-driven mechanism, which leads to changes in crystal symmetry and layer stackings that introduce attractive physical properties different from their bulk and few-layer nanostructures. However, controllable growth of spirals is challenging and their growth mechanisms are poorly understood. Here, we report the controllable growth of WS 2 spiral nanoplates with different stackings by a vapor phase deposition route and investigate their formation mechanisms by combining atomic force microscopy with second harmonic generation imaging. Previously not observed "spiral arm" features could be explained as covered dislocation spiral steps, and the number of spiral arms correlates with the number of screw dislocations initiated at the bottom plane. The supersaturation-dependent growth can generate new screw dislocations from the existing layers, or even new layers templated by existing screw dislocations. Different number of dislocations and orientation of new layers result in distinct morphologies, different layer stackings, and more complex nanostructures, such as triangular spiral nanoplates with hexagonal spiral pattern on top. This work provides the understanding and control of dislocation-driven growth of 2D nanostructures. These spiral nanostructures offer diverse candidates for probing the physical properties of layered materials and exploring new applications in functional nanoelectronic and optoelectronic devices.

Dislocation Strengthening without Ductility Trade-off in Metastable Austenitic Steels.

PubMed

Liu, Jiabin; Jin, Yongbin; Fang, Xiaoyang; Chen, Chenxu; Feng, Qiong; Liu, Xiaowei; Chen, Yuzeng; Suo, Tao; Zhao, Feng; Huang, Tianlin; Wang, Hongtao; Wang, Xi; Fang, Youtong; Wei, Yujie; Meng, Liang; Lu, Jian; Yang, Wei

2016-10-14

Strength and ductility are mutually exclusive if they are manifested as consequence of the coupling between strengthening and toughening mechanisms. One notable example is dislocation strengthening in metals, which invariably leads to reduced ductility. However, this trend is averted in metastable austenitic steels. A one-step thermal mechanical treatment (TMT), i.e. hot rolling, can effectively enhance the yielding strength of the metastable austenitic steel from 322 ± 18 MPa to 675 ± 15 MPa, while retaining both the formability and hardenability. It is noted that no boundaries are introduced in the optimized TMT process and all strengthening effect originates from dislocations with inherited thermal stability. The success of this method relies on the decoupled strengthening and toughening mechanisms in metastable austenitic steels, in which yield strength is controlled by initial dislocation density while ductility is retained by the capability to nucleate new dislocations to carry plastic deformation. Especially, the simplicity in processing enables scaling and industrial applications to meet the challenging requirements of emissions reduction. On the other hand, the complexity in the underlying mechanism of dislocation strengthening in this case may shed light on a different route of material strengthening by stimulating dislocation activities, rather than impeding motion of dislocations.

Dislocation Multiplication in the Early Stage of Deformation in Mo Single Crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsiung, L.; Lassila, D.H.

Initial dislocation structure in annealed high-purity Mo single crystals and deformation substructure in a crystal subjected to 1% compression have been examined and studied using transmission electron microscopy (TEM) techniques in order to investigate dislocation multiplication mechanisms in the early stage of plastic deformation. The initial dislocation density is in a range of 10{sup 6} {approx} 10{sup 7} cm{sup -2}, and the dislocation structure is found to contain many grown-in superjogs along dislocation lines. The dislocation density increases to a range of 10{sup 8} {approx} 10{sup 9} cm{sup -2}, and the average jog height is also found to increase aftermore » compressing for a total strain of 1%. It is proposed that the preexisting jogged screw dislocations can act as (multiple) dislocation multiplication sources when deformed under quasi-static conditions. The jog height can increase by stress-induced jog coalescence, which takes place via the lateral migration (drift) of superjogs driven by unbalanced line-tension partials acting on link segments of unequal lengths. The coalescence of superjogs results in an increase of both link length and jog height. Applied shear stress begins to push each link segment to precede dislocation multiplication when link length and jog height are greater than critical lengths. This ''dynamic'' dislocation multiplication source is suggested to be crucial for the dislocation multiplication in the early stage of plastic deformation in Mo.« less

A phase field dislocation dynamics model for a bicrystal interface system: An investigation into dislocation slip transmission across cube-on-cube interfaces

DOE PAGES

Zeng, Y.; Hunter, A.; Beyerlein, I. J.; ...

2015-09-14

In this study, we present a phase field dislocation dynamics formulation designed to treat a system comprised of two materials differing in moduli and lattice parameters that meet at a common interface. We apply the model to calculate the critical stress τ crit required to transmit a perfect dislocation across the bimaterial interface with a cube-on-cube orientation relationship. The calculation of τ crit accounts for the effects of: 1) the lattice mismatch (misfit or coherency stresses), 2) the elastic moduli mismatch (Koehler forces or image stresses), and 3) the formation of the residual dislocation in the interface. Our results showmore » that the value of τ crit associated with the transmission of a dislocation from material 1 to material 2 is not the same as that from material 2 to material 1. Dislocation transmission from the material with the lower shear modulus and larger lattice parameter tends to be easier than the reverse and this apparent asymmetry in τ crit generally increases with increases in either lattice or moduli mismatch or both. In efforts to clarify the roles of lattice and moduli mismatch, we construct an analytical model for τcrit based on the formation energy of the residual dislocation. We show that path dependence in this energetic barrier can explain the asymmetry seen in the calculated τ crit values.« less

Computational study of dislocation based mechanisms in FCC materials

NASA Astrophysics Data System (ADS)

Yellakara, Ranga Nikhil

Understanding the relationships between microstructures and properties of materials is a key to developing new materials with more suitable qualities or employing the appropriate materials in special uses. In the present world of material research, the main focus is on microstructural control to cost-effectively enhance properties and meet performance specifications. This present work is directed towards improving the fundamental understanding of the microscale deformation mechanisms and mechanical behavior of metallic alloys, particularly focusing on face centered cubic (FCC) structured metals through a unique computational methodology called three-dimensional dislocation dynamics (3D-DD). In these simulations, the equations of motion for dislocations are mathematically solved to determine the evolution and interaction of dislocations. Microstructure details and stress-strain curves are a direct observation in the simulation and can be used to validate experimental results. The effect of initial dislocation microstructure on the yield strength has been studied. It has been shown that dislocation density based crystal plasticity formulations only work when dislocation densities/numbers are sufficiently large so that a statistically accurate description of the microstructure can be obtainable. The evolution of the flow stress for grain sizes ranging from 0.5 to 10 mum under uniaxial tension was simulated using an improvised model by integrating dislocation pile-up mechanism at grain boundaries has been performed. This study showed that for a same initial dislocation density, the Hall--Petch relationship holds well at small grain sizes (0.5--2 mum), beyond which the yield strength remains constant as the grain size increases. Various dislocation-particle interaction mechanisms have been introduced and investigations were made on their effect on the uniaxial tensile properties. These studies suggested that increase in particle volume fraction and decrease in particle

Hip biomechanics during stair ascent and descent in people with and without hip osteoarthritis.

PubMed

Hall, Michelle; Wrigley, Tim V; Kean, Crystal O; Metcalf, Ben R; Bennell, Kim L

2017-07-01

Hip osteoarthritis (OA) is often associated with pain and impaired function. Understanding biomechanical alterations in patients with hip OA during challenging activities such as stair use is important to inform treatments. The aim of this study was to determine whether kinematics and kinetics during stair ambulation differed between people with hip OA and healthy controls. Fifteen participants with symptomatic and radiographic hip OA and 15 asymptomatic healthy controls underwent 3-D motion analysis during stair ascent and descent. Trunk, pelvis, and hip kinematics as well as hip kinetics were evaluated. Analyses were performed unadjusted and adjusted for speed and leg length. In both the unadjusted and adjusted analyses, participants with hip OA ascended stairs with less hip range of motion in all three planes and a lower peak external rotation moment compared to controls. In the unadjusted analysis, hip OA participants descended stairs with greater ipsilateral trunk lean, less sagittal plane range of motion, lower peak extension moment, lower peak external rotation moment, and greater hip adduction moment impulse compared to controls. In the adjusted results, peak internal rotation moment and hip adduction moment impulse were greater in hip OA participants compared to controls. Findings show that individuals with hip OA display limited range of hip joint movement, particularly during stair ascent, and overall indicate the use of strategies (e.g., trunk lean; lower peak external rotation moment; higher adduction moment impulse) that implicate altered hip abductor function. Future research is required to further understand the implications of these findings on hip OA. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1505-1514, 2017. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

The Role of Hip Arthroscopy in Investigating and Managing the Painful Hip Resurfacing Arthroplasty.

PubMed

Mei-Dan, Omer; Pascual-Garrido, Cecilia; Moreira, Brett; McConkey, Mark O; Young, David A

2016-03-01

To determine the safety and efficacy of hip arthroscopy performed in the peripheral compartment as a diagnostic and therapeutic treatment option for patients with hip pain after hip resurfacing surgery. Indications for hip arthroscopy after hip resurfacing included patients with a symptomatic hip-resurfaced arthroplasties who did not respond to nonoperative treatment. Patients who underwent a hip arthroscopy after a painful hip resurfacing were included with a minimum of 1 year follow-up. Subgroup analysis was performed according to whether an established diagnosis was made before arthroscopic intervention or not. Subjective measures were based on Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores, and results were calculated and analyzed. We included 68 patients (26 male [38%] and 42 female [62%]) who underwent subsequent hip arthroscopy from a population of 978 consecutive hip-resurfaced arthroplasties performed between 1999 and 2010. The average age was 58 (range, 37 to 78 years). The mean follow-up after hip arthroscopy was 3.4 years (range, 12 months to 5.8 years). Patients who had an established diagnosis (n = 41) before hip arthroscopy showed statistical improvement in their WOMAC scores (7 to 2, P < .001). Only 3 (7%) of these 41 patients failed and were converted to a total hip replacement (THR); however, patients who did not have an established diagnosis (n = 27) before undergoing hip arthroscopy showed statistical worsening of the WOMAC (15 to 21, P = .002). Ten (37%) of these 27 patients without a diagnosis failed and needed to be converted to a THR. A significant correlation was found between the collections found on ultrasound (psoas bursa and/or in the hip joint) and the need for synovectomy (P = .01). The overall revision rate to THR after hip resurfacing in our group of patients was 1.3% (n = 13). Female patients were more likely to require postresurfacing hip arthroscopy with 42 (60%) female to only 26 (40%) male

An unusual variety of simultaneous fracture dislocation pattern: medial swivel dislocation of talonavicular joint with displaced fractures of the fourth and fifth metatarsals.

PubMed

Inal, Sermet; Inal, Canan

2013-01-01

In published studies, a very rare, special type of Chopart dislocation termed a swivel dislocation has been reported. This injury is characterized by dislocation of the talonavicular joint, but the calcaneocuboid joint remains intact. The foot creates a typical rotational movement without inversion or eversion. The axis of rotation is the interosseous talocalcaneal ligament, which remains intact. We report the case of an 18-year-old male who had experienced a medial swivel dislocation of the talonavicular joint associated with displaced fractures of the fourth and fifth metatarsals. The occurrence, features, and method of treatment of this rare injury are presented. Copyright © 2013 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Dislocation Structure and Mobility in hcp He 4

DOE PAGES

Landinez Borda, Edgar Josue; Cai, Wei; de Koning, Maurice

2016-07-20

We assess the core structure and mobility of the screw and edge basal-plane dislocations in hcp 4He using path-integral Monte Carlo simulations. Our findings provide key insights into recent interpretations of giant plasticity and mass flow junction experiments. First, both dislocations are dissociated into nonsuperfluid Shockley partial dislocations separated by ribbons of stacking fault, suggesting that they are unlikely to act as one-dimensional channels that may display Lüttinger-liquid-like behavior. Second, the centroid positions of the partial cores are found to fluctuate substantially, even in the absence of applied shear stresses. This implies that the lattice resistance to motion of themore » partial dislocations is negligible, consistent with the recent experimental observations of giant plasticity. Our results indicate that both the structure of the partial cores and the zero-point fluctuations play a role in this extreme mobility.« less

The relationship between alpha angle and resistive index of the femoral epiphysis in the normal and abnormal infant hip.

PubMed

Amodio, John; Rivera, Rafael; Pinkney, Lynne; Strubel, Naomi; Fefferman, Nancy

2006-08-01

The arterial vascularity of the hip has been investigated in normal infants using duplex Doppler sonography. This study addressed the differences in hip vascularity in infants with respect to gender and acetabular morphology. To determine whether there is a relationship between the resistive index of the vessels of the femoral chondroepiphysis and the alpha angle in normal infant hips and in those with developmental dysplasia of the hip. We studied 76 hips (38 patients) with gray-scale and power Doppler US. The patients were referred because of a possible abnormal clinical hip examination or had risk factors for developmental dysplasia of the hip. The infants ranged in age from 1 day to 6 weeks. There were 13 boys and 25 girls. Gray-scale images were initially performed in the coronal and transverse planes to evaluate acetabular morphology, alpha angle and position of the femoral chondroepiphysis relative to the acetabulum. The hips were then examined with power Doppler US, in both sagittal and transverse planes, to identify arterial vessels within the femoral epiphysis. Resistive indices were then recorded from the spectral analysis in each vessel identified. Each examination was performed by one of five pediatric radiologists. Mixed model regression was used to assess the relationship between resistive index and alpha angle, age and gender. Of the 76 hips, 34 had an alpha angle of 60 degrees or greater and were classified as normal, 26 had an alpha angle between 50 degrees and 59 degrees and were classified as immature, and 13 had an alpha angle of less than 50 degrees and were either subluxed or dislocated at the time of examination. At least two vessels were documented in each femoral epiphysis except in three hips, in which no vessels could be documented because of technical factors. There was a statistically significant linear relationship between the alpha angle and resistive index, such that the resistive index tended to rise with increasing alpha angle (P

Strength and Dislocation Structure Evolution of Small Metals under Vibrations

NASA Astrophysics Data System (ADS)

Ngan, Alfonso

2015-03-01

It is well-known that ultrasonic vibration can soften metals, and this phenomenon has been widely exploited in industrial applications concerning metal forming and bonding. In this work, we explore the effects of a superimposed small oscillatory load on metal plasticity, from the nano- to macro-size range, and from audible to ultrasonic frequency ranges. Macroscopic and nano-indentation were performed on aluminum, copper and molybdenum, and the results show that the simultaneous application of oscillatory stresses can lower the hardness of these samples. More interestingly, EBSD and TEM observations show that subgrain formation and reduction in dislocation density generally occurred when stress oscillations were applied. These findings point to an important knowledge gap in metal plasticity - the existing understanding of ultrasound softening in terms of the vibrations either imposing additional stress waves to augment the quasi-static applied load, or heating up the metal, whereas the metal's intrinsic deformation resistance or dislocation interactive processes are assumed unaltered by the ultrasound, is proven wrong by the present results. Furthermore, in the case of nanoindentation, the Continuous Stiffness Measurement technique for contact stiffness measurement assumes that the imposed signal-carrier oscillations do not intrinsically alter the material properties of the specimen, and again, the present results prove that this can be wrong. To understand the enhanced subgrain formation and dislocation annihilation, Discrete Dislocation Dynamics (DDD) simulations were carried out and these show that when an oscillatory stress is superimposed on a quasi-static applied stress, reversals of motion of dislocations may occur, and these allow the dislocations to revisit repeatedly suitable configurations for annihilation. DDD, however, was unable to predict the observed subgrain formation presumably because the number of dislocations that can be handled is not large

Athletic Hip Injuries.

PubMed

Lynch, T Sean; Bedi, Asheesh; Larson, Christopher M

2017-04-01

Historically, athletic hip injuries have garnered little attention; however, these injuries account for approximately 6% of all sports injuries and their prevalence is increasing. At times, the diagnosis and management of hip injuries can be challenging and elusive for the team physician. Hip injuries are seen in high-level athletes who participate in cutting and pivoting sports that require rapid acceleration and deceleration. Described previously as the "sports hip triad," these injuries consist of adductor strains, osteitis pubis, athletic pubalgia, or core muscle injury, often with underlying range-of-motion limitations secondary to femoroacetabular impingement. These disorders can happen in isolation but frequently occur in combination. To add to the diagnostic challenge, numerous intra-articular disorders and extra-articular soft-tissue restraints about the hip can serve as pain generators, in addition to referred pain from the lumbar spine, bowel, bladder, and reproductive organs. Athletic hip conditions can be debilitating and often require a timely diagnosis to provide appropriate intervention.

Modeling collective behavior of dislocations in crystalline materials

NASA Astrophysics Data System (ADS)

Varadhan, Satya N.

Elastic interaction of dislocations leads to collective behavior and determines plastic response at the mesoscale. Notable characteristics of mesoscale plasticity include the formation of dislocation patterns, propagative instability phenomena due to strain aging such as the Luders and Portevin-Le Chatelier effects, and size-dependence of low stress. This work presents a unified approach to modeling collective behavior based on mesoscale field dislocation mechanics and crystal plasticity, using constitutive models with physical basis. Successful application is made to: compression of a bicrystal, where "smaller is stronger"---the flow stress increases as the specimen size is reduced; torsional creep of ice single crystals, where the plastic strain rate increases with time under constant applied torque; strain aging in a single crystal alloy, where the transition from homogeneous deformation to intermittent bands to continuous band is captured as the applied deformation rate is increased. A part of this work deals with the kinematics of dislocation density evolution. An explicit Galerkin/least-squares formulation is introduced for the quasilinear evolution equation, which leads to a symmetric and well-conditioned system of equations with constant coefficients, making it attractive for large-scale problems. It is shown that the evolution equation simplifies to the Hamilton-Jacobi equations governing geometric optics and level set methods in the following physical contexts: annihilation of dislocations, expansion of a polygonal dislocation loop and operation of a Frank-Read source. The weak solutions to these equations are not unique, and the numerical method is able to capture solutions corresponding to shock as well as expansion fans.

21 CFR 888.3390 - Hip joint femoral (hemi-hip) metal/polymer cemented or uncemented prosthesis.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hip joint femoral (hemi-hip) metal/polymer... § 888.3390 Hip joint femoral (hemi-hip) metal/polymer cemented or uncemented prosthesis. (a) Identification. A hip joint femoral (hemi-hip) metal/polymer cemented or uncemented prosthesis is a two-part...

Edge-on dislocation loop in anisotropic hcp zirconium thin foil

NASA Astrophysics Data System (ADS)

Wu, Wenwang; Xia, Re; Qian, Guian; Xu, Shucai; Zhang, Jinhuan

2015-10-01

Edge-on dislocation loops with 〈 a 〉 -type and 〈 c 〉 -type of Burgers vectors can be formed on prismatic or basel habit planes of hexagonal close-packed (hcp) zirconium alloys during in-situ ion irradiation and neutron irradiation experiments. In this work, an anisotropic image stress method was employed to analyze the free surface effects of dislocation loops within hcp Zr thin foils. Calculation results demonstrate that image stress has a remarkable effect on the distortion fields of dislocation loops within infinite medium, and the image energy becomes remarkable when dislocation loops are situated close to the free surfaces. Moreover, image forces of the 1 / 2 〈 0001 〉 (0001) dislocation loop within (0001) thin foil is much stronger than that of the 1 / 3 〈 11 2 bar 0 〉 (11 2 bar 0) dislocation loop within (11 2 bar 0) thin foil of identical geometrical configurations. Finally, image stress effect on the physical behaviors of loops during in-situ ion irradiation experiments is discussed.

Bilaterally Primary Cementless Total Hip Arthroplasty for Severe Hip Ankylosis with Ankylosing Spondylitis.

PubMed

Feng, Dong-Xu; Zhang, Kun; Zhang, Yu-Min; Nian, Yue-Wen; Zhang, Jun; Kang, Xiao-Min; Wu, Shu-Fang; Zhu, Yang-Jun

2016-08-01

Total hip arthroplasty is a reliable therapeutic intervention in patients with ankylosing spondylitis, in whom the aims of surgery are to reduce pain, restore hip function and improve quality of life. The current study is a retrospective analysis of the clinical and radiographic findings in a consecutive series of patients with hip ankylosis associated with severe ankylosing spondylitis who underwent bilateral primary total hip arthroplasty using non-cemented components. From June 2008 to May 2012, total hip arthroplasty was performed on 34 hips in 17 patients with bilateral ankylosis caused by ankylosing spondylitis. The study patients included 13 men and 4 women with a mean age of 24.2 years. The mean duration of disease was 8.3 years and the average duration of hip involvement was 7.6 years. All patients had severe hip pain and dysfunction with bilateral bony ankylosis and no range of motion preoperatively and all underwent bilateral cementless total hip arthroplasty performed by a single surgeon. Joint pain, range of motion (ROM), and Harris hip scores were assessed to evaluate the postoperative results. At a mean follow-up of 31.7 months, all patients had experienced significant clinical improvement in function, ROM, posture and ambulation. At the final follow-up, the mean postoperative flexion ROM was 134.4° compared with 0° preoperatively. Similar improvements were seen in hip abduction, adduction, internal rotation and external rotation. Postoperatively, 23 hips were completely pain-free, six had only occasional discomfort, three mild to moderate pain and two severe pain. The average Harris Hip Score improved from 23.7 preoperatively to 65.8 postoperatively. No stems had loosened at the final follow-up in any patient, nor had any revision surgery been required. Bilateral severe hip ankylosis in patients with ankylosing spondylitis can be treated with cementless bilateral synchronous total hip arthroplasty, which can greatly improve hip joint function and

Investigation of dislocation cluster evolution during directional solidification of multicrystalline silicon

NASA Astrophysics Data System (ADS)

Oriwol, Daniel; Trempa, Matthias; Sylla, Lamine; Leipner, Hartmut S.

2017-04-01

Dislocation clusters are the main crystal defects in multicrystalline silicon and are detrimental for solar cell efficiency. They were formed during the silicon ingot casting due to the relaxation of strain energy. The evolution of the dislocation clusters was studied by means of automated analysing tools of the standard wafer and cell production giving information about the cluster development as a function of the ingot height. Due to the observation of the whole wafer surface the point of view is of macroscopic nature. It was found that the dislocations tend to build clusters of high density which usually expand in diameter as a function of ingot height. According to their structure the dislocation clusters can be divided into light and dense clusters. The appearance of both types shows a clear dependence on the orientation of the grain growth direction. Additionally, a process of annihilation of dislocation clusters during the crystallization has been observed. To complement the macroscopic description, the dislocation clusters were also investigates by TEM. It is shown that the dislocations within the subgrain boundaries are closely arranged. Distances of 40-30 nm were found. These results lead to the conclusion that the dislocation density within the cluster structure is impossible to quantify by means of etch pit counting.