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PubMed1997

[Cup dissociation after reduction of a dislocated hip hemiarthroplasty].

PURPOSE OF THE STUDY: Close reduction of a bipolar hemiarthroplasty dislocation may induce dissociation between the cup and the prosthetic ball head. This rare complication leads to reoperation. CASE REPORT: Two women 84 and 85 years' old suffering from femoral head fracture were treated by bipolar hemiarthroplasty through a postero-lateral approach. After the first post-operative month, a posterior dislocation has occurred. Close reduction, without anesthesia dislocated the intraprosthetic joint. DISCUSSION: Dislocation rate is lower for bipolar hemiarthroplasty than for total hip arthroplasty. Reason for these two dislocation was supposed to be a "bottle-opener" effect's by locking the cup on to the posterior acetabular rim. Limb traction is responsible for intra-prosthetic iatrogenic dislocation. CONCLUSION: Anesthesia should be considered as necessary for prosthesis bipolar hemiarthroplasties dislocation treatment. The authors have moved to a different implant and modified their surgical approach (antero lateral). These modifications were introduced in order to reduce the rate of hip dislocation and above all the event of intraprosthetic dislocation when close reduction was necessary.

Aged↗
PubMed1997

Dislocation of the pituitary gland by sphenocavernous meningiomas.

BACKGROUND: Dislocation of the pituitary gland from the sella turcia by tumor has only very rarely been described. To date, only two cases have appeared in the neurosurgical literature. METHODS: After intraoperative identification of pituitary dislocation in five patients with cavernous sinus meningiomas, a review of our most recent 20 patients with cavernous sinus meningiomas was performed. A subgroup of sphenocavernous meningiomas was identified, as were the associations between pituitary dislocation and the patient's endocrinologic status. RESULTS: Of 20 consecutive patients with cavernous sinus meningiomas, seven tumors could be subclassified as sphenocavernous meningiomas due to the significant amount of tumor extension into the sphenoid sinus. At the time of surgery, dislocation of the pituitary gland from the sella into the suprasellar cistern was observed in five of seven of these patients. Four of the five patients with pituitary dislocation had evidence of hypopituitarism, whereas there was no evidence of this condition in the two patients with sphenocavernous meningiomas without pituitary dislocation. CONCLUSIONS: Pituitary dislocation in these patients is likely due to the physical dislocation of the pituitary gland from the sella, through an incompetent diaphragma sella, and by the tumorous extension in the sphenoid sinus. The extension of a cavernous sinus meningioma into the sphenoid sinus, and specifically the sella turcica, may be via the intercavernous venous sinuses. The lack of endocrinologic improvement suggests that the hypopituitarism noted in these patients is likely due to disturbance of the pituitary microcirculation with subsequent pituitary ischemia. The possibility of pituitary dislocation in patients with sphenocavernous meningiomas, especially those with panhypopituitarism, should be considered and searched for at the time of surgery.

Adult↗
PubMed2004

Dislocation-driven surface dynamics on solids.

Dislocations are line defects that bound plastically deformed regions in crystalline solids. Dislocations terminating on the surface of materials can strongly influence nanostructural and interfacial stability, mechanical properties, chemical reactions, transport phenomena, and other surface processes. While most theoretical and experimental studies have focused on dislocation motion in bulk solids under applied stress and step formation due to dislocations at surfaces during crystal growth, very little is known about the effects of dislocations on surface dynamics and morphological evolution. Here we investigate the near-equilibrium dynamics of surface-terminated dislocations using low-energy electron microscopy. We observe, in real time, the thermally driven nucleation and shape-preserving growth of spiral steps rotating at constant temperature-dependent angular velocities around cores of dislocations terminating on the (111) surface of TiN in the absence of applied external stress or net mass change. We attribute this phenomenon to point-defect migration from the bulk to the surface along dislocation lines. Our results demonstrate that dislocation-mediated surface roughening can occur even in the absence of deposition or evaporation, and provide fundamental insights into mechanisms controlling nanostructural stability.

Journal Article↗
PubMed2006

Ubiquitination of MHC class I heavy chains is essential for dislocation by human cytomegalovirus-encoded US2 but not US11.

The human cytomegalovirus-encoded glycoproteins US2 and US11 target newly synthesized major histocompatibility complex class I heavy chains for degradation by mediating their dislocation from the endoplasmic reticulum back into the cytosol, where they are degraded by proteasomes. A functional ubiquitin system is required for US2- and US11-dependent dislocation of the class I heavy chains. It has been assumed that the class I heavy chain itself is ubiquitinated during the dislocation reaction. To test this hypothesis, all lysines within the class I heavy chain were substituted. The lysine-less class I molecules could no longer be dislocated by US2 despite the fact that the interaction between the two proteins was maintained. Interestingly, US11 was still capable of dislocating the lysine-less heavy chains into the cytosol. Ubiquitination does not necessarily require lysine residues but can also occur at the N terminus of a protein. To investigate the potential role of N-terminal ubiquitination in heavy chain dislocation, a lysine-less ubiquitin moiety was fused to the N terminus of the class I molecule. This lysine-less fusion protein was still dislocated in the presence of US11. Ubiquitination could not be detected in vitro, either for the lysine-less heavy chains or for the lysine-less ubiquitin-heavy chain fusion protein. Our data show that although dislocation of the lysineless class I heavy chains requires a functional ubiquitin system, the heavy chain itself does not serve as the ubiquitin acceptor. This finding sheds new light on the role of the ubiquitin system in the dislocation process.

Animals↗
PubMed2004

HVEM characterization of crack tip dislocations in silicon crystals.

Crack tip dislocations in silicon crystals have been studied using high voltage electron microscopy (HVEM). The dislocation images have been investigated by comparing the observed images to those that were simulated. Dislocation images were computed in the conditions g x b = 0, 1 or 2 (g: diffraction vector, b: Burgers vector). The characteristics of 60 degrees dislocations were examined in detail since these dislocations are not characterized only by the condition g x b = 0 criterion. The computed images were in good agreement with those observed by HVEM. Residual contrasts of 60 degrees dislocations under the condition g x b = 0 exhibited characteristic black-and-white contrasts, which can contribute to the characterization of the dislocations. Such characterization of dislocations is essential in order to clarify the dislocation mechanism which controls the fracture toughness of materials.

Computer Simulation↗
PubMed2005

Dislocation rate after hip hemiarthroplasty in patients with tumor-related conditions.

BACKGROUND: Hemiarthroplasty is frequently used to treat femoral neck insufficiency resulting from neoplastic disease in the proximal part of the femur. The authors of a recent study analyzed the dislocation rates following hemiarthroplasty but excluded patients with tumor involvement of the site of the surgery as they hypothesized that the dislocation rates would be markedly higher in such patients. The current study was performed to compare the dislocation rate following hemiarthroplasties performed in patients without tumor involvement with the rate following hemiarthroplasties in patients with tumor involvement of the surgical site. METHODS: Patients who had undergone hemiarthroplasty following resection of a tumor involving the proximal part of the femur were identified in a total joint registry, and the patients' charts were reviewed retrospectively to determine dislocation rates, preoperative conditions, and postoperative outcomes and treatments. Between 1974 and 2001, 1812 patients were treated with hemiarthroplasty for reasons other than tumor involvement and 320 hemiarthroplasties were performed because of tumor-related conditions. The patients who were treated for a tumor-related condition were younger, and a higher proportion of them were men. RESULTS: The ten-year dislocation rate after the hemiarthroplasties performed for tumor-related conditions (10.9%) was higher than that following the hemiarthroplasties performed for non-tumor-related conditions (2.1%) (p = 0.002). The median time to dislocation in the patients with a tumor-related condition (twenty-four days) was shorter than that for the patients without tumor involvement (thirty-seven days). Preservation of the greater trochanter in patients with tumor involvement did not have a significant influence on the dislocation rate, but it showed a favorable trend toward decreasing that rate (hazard ratio = 3.5, p = 0.06). CONCLUSIONS: The short-term and long-term dislocation rates associated with hemiarthroplasties performed for a tumor-related condition at the site of the surgery were significantly higher than those associated with hemiarthroplasties performed for reasons other than tumor involvement. Preservation of the greater trochanter showed a trend toward decreasing the likelihood of dislocation following the hemiarthroplasty, and it was more influential than the level of resection and the extent of soft-tissue compromise. We think that preservation of the greater trochanter should be attempted when it is justifiable according to the principles of oncologic surgery.

Adolescent↗
PubMed2000

[Cause and management of dislocated nuclear fragments during phacoemulsification].

OBJECTIVE: To investigate the cause and management of posteriorly dislocated lens nucleus in the vitreous cavity during phacoemulsification. METHODS: The authors performed a retrospective study of 18 patients with dislocation of nuclear fragment into vitreous cavity during phacoemulsification at Tong Ren Hospital from August 1994 to January 1999. RESULTS: 4 cases with dislocated nuclei floated in the anterior vitreous were removed by a lens loop from limbal extensive incision. 2 cases with their dislocated nuclei less than 1/4 of the normal size were under follow-up for 3 - 4 years, and no complications were observed. The final outcome in 1 case with a dislocated nucleus half of its normal size was ocular atrophy as a result of phacoanaphylactic endophthalmitis. 11 cases underwent pars plana vitrectomy. In the operation the nuclei were floated anteriorly by injection of perfluoro-1, 3-dimethylcyclohexane, then they were removed by a lens loop through the limbus and in 2 cases they were fragmented by ultrasound. The main post-operative complication was corneal edema. The final visual acuities generally were improved in varying degrees in 1 month to 4 years of follow-up. CONCLUSIONS: During phacoemulsification, the dislocation of a nucleus is liable to first occur in the peripheral sculpting stage, and secondly in central sculpting stage. A radial tear extending posteriorly from a discontinuous anterior capsulorrhexis is the major risk factor predisposing to posterior dislocation of the nucleus or nuclear fragment. During phacoemulsification, vitrectomy should be performed as soon as possible for a nucleus dislocated into middle or posterior vitreous cavity, and it is a safe and effective method for management of dislocated nucleus.

Adult↗
PubMed2001

[Manubriosternal dislocation caused by indirect flexion-compression trauma. A case report and review of the literature].

Manubriosternal dislocation caused by indirect flexion-compression trauma is an extremely rare condition. Two forms of manubriosternal luxation are distinguished: in type I the sternum is dislocated posterior and in type II anterior to the manubrium. Direct or indirect trauma may cause manubriosternal dislocation. Mode of injury in direct trauma is mostly a head-on collition in a motor accident resulting either in type I or type II luxation. The unusual origin of manubriosternal dislocation by indirect trauma is put down to flexion-compression injuries of the thoracic spine and results in a type II dislocation. Predisposition to manubriosternal dislocation by indirect trauma consists in rheumatoid arthritis or extreme forms of kyphosis. Outcome of many patients treated conservatively after initial reposition with adhesive tape, symptomatic pain therapy, cryotherapy and prohibition of any physical training over several weeks is subluxation or complete luxation of the manubriosternal joint. This condition may lead to chronic pain, periarticular calcification with ankylosis and progredient deformation. Lacking a controlled study for treatment of manubriosternal dislocation a standard therapeutic regime could not be established yet. In the literature only a few case-reports of patients undergoing operative therapy are published. We report a type II dislocation of the manubriosternal joint caused by indirect flexion-compression trauma. We achieved a very good long-term result using a 8-hole 1/3 tubular plate for fixation of the manubriosternal joint after reposition.

Adult↗
PubMed2005

[Femoral neck fracture complicating orthopedic reposition of a dislocated hip: four cases].

Posterior dislocation of the femoral head with fracture is an exceptional hip injury. Emergency reduction is required. Reposition into the acetabular cavity of the dislocated femoral head may not be feasible. Irreducibility, instability, and more rarely accidental fracture of the femoral neck may also occur. We encountered this latter complication in four patients and report here its frequency and mechanism and propose preventive therapeutic measures. Seventy dislocations and fracture-dislocations of the hip were treated in our unit from March 1997 to February 2003. Among these cases, fourteen hip dislocations were complicated by femoral head fractures. Fracture of the femoral neck occurred during reduction in four. All four cases occurred in men, mean age 49.7 years, who were traffic accident victims (drivers or passengers). There were two Pipkin IV fracture-dislocations and two Pipkin II. The first reduction, achieved under general anesthesia in an emergency setting, was performed by an orthopedic surgeon in one patient and a general surgeon in three patients. Arthroplasty was used to treat the femoral neck fracture in three patients and pinning in one. We reviewed retrospectively the clinical and imaging data before and after reduction. Sub-capital fracture situated 4.0 cm (mean, range 3.5-4.5 cm) from the lesser trochanter occurred in all four cases. The head remained attached above and posteriorly to the acetabulum and was rotated less than 90 degrees . The fragment remaining in the acetabulum was displaced in two cases. In one patient, the fracture-dislocation of the head was associated with a fracture of the posterior rim of the acetabulum. This complication appears to result from an abrupt inappropriate reduction movement. The neck fracture would occur when capsulomuscular retention of the femoral head is associated with a head defect which catches on the rim of the acetabulum during the reduction movement. Neck fracture during reduction of traumatic hip dislocation is a serious complication. Prevention of this iatrogenic event requires a slow, progressive reduction limiting the trauma to a minimum; first intention open surgery may be required in selected cases.

Accidents, Traffic↗
PubMed1987

Trochanteric advancement for recurrent dislocation after total hip arthroplasty.

Twenty-one patients had trochanteric advancement after experiencing an average of 3.9 dislocations in a mean period of 46 weeks following total hip arthroplasty. Before trochanteric advancement was performed, component malposition and mechanical impingement were excluded as causes of dislocation. Radiographic measurements revealed that the trochanter was advanced an average of 16 +/- 7.7 mm (1 SD). Four patients, all with rheumatoid arthritis, had trochanteric migration greater than 1 cm. Seventeen of the 21 hips had no further dislocations following trochanteric advancement, with mean follow-up period of 2.7 years. Two patients dislocated because of extremes in hip position and had no further dislocations. Two patients dislocated who had trochanteric migration greater than 1 cm. Only one patients with a technically satisfactory trochanteric advancement continued to dislocate repeatedly. In patients without component malposition or obvious sources of impingement, trochanteric advancement is an effective and safe procedure for prevention of recurrent dislocations after total hip arthroplasty.

Adult↗
PubMed2002

A test model of hip brace for prevention of dislocation after total hip arthroplasty (Zetton Band).

Hip dislocations remain an intractable problem in patients with soft tissue impairment, particularly in those with muscle weakness around the hip, such as those who have undergone revision total hip arthroplasty (THA). At the authors' hospital, postoperative dislocations were observed in 10 of 154 hips between January 1985 and June 1988. Five hips required re-replacement. Conventional measures to prevent or treat post-THA dislocations have been anti-dislocation pants for soft fixation and a cast or abduction-forcing braces for firm fixation. However, the anti-dislocation pants for soft fixation were not as effective as indicated by the above 10 postoperative dislocations. The firm fixation techniques are considered to cause a reduction in muscle strength, causing psychological stress and poor activity of daily living (ADL). The authors devised a soft brace for easy application and prepared its test model to prevent muscle weakening, allow stability of the hip during rotation and avoid restrictions in ADL. This brace was applied to a patient who had 3 dislocations in a short period after being discharged who sustained a postoperative dislocation and achieved good results.

Aged↗
PubMed2002

Open surgical repair restores joint forces that resist glenohumeral dislocation.

Traumatic anterior shoulder instability is a clinical problem often observed in athletes participating in overhead activities. The standard treatment for this condition is surgical repair, which may be accomplished by an open or arthroscopic procedure. The current authors assessed the strength of open repair, by comparing glenohumeral joint forces in intact specimens with specimens with anterior dislocation and open repair. Eighteen shoulders from cadavers were tested on a custom shoulder dislocation device with simulated muscle forces. Bankart lesions were repaired using a three-suture anchor technique combined with capsular advancement. Capsular failures were addressed by sharp dissection of the labrum from bone, then repaired as above, and the experiment was repeated. One-way analysis of variance was used for analyses. All specimens dislocated anteroinferiorly, eight dislocated by bony Bankart failure, and 10 dislocated by capsular failure. Maximum joint compression force for the initial dislocation was 760 +/- 79 N for the specimens with Bankart failures and 690 +/- 59 N for the specimens with capsular failures. The maximum joint compression force for dislocation after repair measured 541 +/- 50 N for the specimens with Bankart failures and 536 +/- 46 N for the specimens with capsular failures. The forces after repair were normalized with respect to the intact shoulders. For specimens with Bankart failures, joint compression and pectoralis major forces were 72% and 62%, respectively, and 79% and 61% for specimens with capsular failures. A three-dimensional digitizing system confirmed restoration of glenohumeral position. These results support clinical data, showing that open Bankart repair adequately restores the static restraints of the glenohumeral joint that resist anteroinferior dislocation.

Aged↗
PubMed2000

Reduction and fixation of sacroiliac joint dislocation by the combined use of S1 pedicle screws and the galveston technique.

STUDY DESIGN: This retrospective study was designed to analyze the results of the treatment with S1 pedicle screws and the Galveston technique of seven patients with sacroiliac dislocation. OBJECTIVES: To evaluate the effectiveness of the combined use of S1 pedicle screws and the Galveston technique for the treatment of sacroiliac dislocation. SUMMARY OF BACKGROUND DATA: Although several procedures for internal fixation of sacroiliac dislocation have been reported, there have been no reports discussing surgical treatment of sacroiliac dislocation by the combined use of S1 pedicle screws and the Galveston technique. METHODS: Seven patients with sacroiliac dislocation were treated with pedicle screws of S1 and iliac rod according to the Galveston technique. In the seven patients, the dislocation was associated with vertical displacement of the sacroiliac joint and rotational deformity of the pelvic ring. They were classified into Type-C pelvic disruption according to the Tile's classification. Three patients with disruption of the symphysis pubis underwent additional fixation of the symphysis using a dynamic compression plate. The remaining four patients were treated by the posterior procedure alone. RESULTS: The vertical displacement was completely reduced in five patients, and the rotational deformity was completely corrected in four patients. The reduction was maintained at the time of the final follow-up evaluation. There were no perioperative complications with the exception of late infection in one patient. CONCLUSIONS: The combined use of S1 pedicle screws and the Galveston technique provided immediate stability and sufficient reduction for sacroiliac dislocation in seven patients in this study. This hybrid internal fixation procedure is useful for reduction and fixation of sacroiliac dislocation associated with the vertical and rotational instability of the pelvic ring.

Adult↗
PubMed2006

An analysis of the risk of hip dislocation with a contemporary total joint registry.

Dislocation rates after total hip arthroplasty in a community setting have not been well documented. We used a community based joint registry to evaluate hip dislocations that occurred within 1 year after total hip arthroplasty. We evaluated patient, implant, and technical factors associated with dislocation, including primary versus revision surgery, femoral head size (28 mm versus > or = 32 mm), operative time, surgeon volume, surgical approach, age, gender, diagnosis, American Society of Anesthesiologists (ASA) classification, and body mass index (BMI). There were 1693 primary total hip arthroplasties and 277 revision procedures performed from 2001-2003. The overall dislocation rate was 1.7% for primary total hip arthroplasties and 5.1% for revision procedures. Patients with ASA scores of 3 or 4 had a 2.3-fold dislocation increase compared with patients with scores of 1 or 2. Patients with rheumatoid arthritis had an increased risk of dislocation. The dislocation rates for primary total hip arthroplasty were 2% for 28 mm heads and 0.7% for heads > or = 32 mm. The surgeon's patient volume, surgical approach, operative time, and body mass index had no effect on dislocation.

Age Distribution↗
PubMed2006

Epidemiology of dislocation after total hip arthroplasty.

Instability after total hip arthroplasty is an important complication. It usually occurs in the immediate postoperative period, but the risk also increases with time. There are numerous surgical treatment options, but they have relatively unpredictable outcomes. Numerous factors are associated with dislocation, but research has mainly focused on surgical factors. Epidemiological factors remain the subject of much debate. We aimed to establish the most significant epidemiological factors in Scotland and in particular the dislocation rate in neuromuscular conditions. The Scottish National arthroplasty nonvoluntary registry is based on SMR01 records (Scottish Morbidity Record) data. We analyzed the Scottish National Arthroplasty Project to find patients' dislocation rates up to 1 year postoperatively for surgeon volume, age, gender, previous surgery, diagnosis, and followup duration. There were 14,314 total hip arthroplasties performed from April 1996 to March 2004 with an annual incidence of dislocation of 1.9%. We found an association between rate of dislocation with age, surgical volume, and previous fracture. However, there was no increase in the rate of dislocation associated with gender or with diagnoses of stroke or Parkinson's disease. Our prognostic assessment of dislocation risk allows assessment for methods of reducing dislocation in high risk patients.

Age Distribution↗
PubMed2006

Role of capsular repair on dislocation in revision total hip arthroplasty.

Dislocation remains one of the most common complications after revision total hip arthroplasty (THA). In contrast to primary THA the posterior capsule has been routinely excised to provide better visualization, but its role in preventing dislocation has been overlooked. We reviewed 69 patients (79 hips) patients who had revision THA with a posterolateral approach to determine if closing the posterior capsule resulted in a fewer dislocations. We followed the patients for a minimum of 24 months (mean 57 months, range, 24-120 months). Two (2.5%) hips dislocated. Both dislocated anteriorly in the immediate postoperative period. One dislocation was from implant malposition and the other occurred in a high risk patient. There were no posterior dislocations and no patients reported any hip subluxation. The historically high dislocation rates with the posterolateral approach can be reduced by carefully balancing soft tissues, ensuring correct implant alignment, meticulously closing the posterior capsule, and reattaching the external rotators.

Adult↗
PubMed2003

An analysis of hip dislocations among snowboarders and skiers: a 10-year prospective study from 1992 to 2002.

BACKGROUND: We evaluated the types and mechanisms of hip dislocation sustained while snowboarding and skiing, a subject about which there have been few studies. METHODS: In a prospective cohort study between 1992 and 2002, we studied 30 snowboarders and 8 skiers with hip dislocations. RESULTS: The incidence of dislocation with or without fracture of the hip joint in snowboarders was five times higher than in skiers (0.45 per 100,000 visits for snowboarders vs. 0.09 for skiers). The most remarkable differences between skiing and snowboarding hip injuries were that in the former there was a significantly higher incidence of anterior hip dislocation (p < 0.05) and in the latter there was a significantly higher incidence of posterior hip dislocation (p < 0.05). Furthermore, the rate of type V hip dislocation (with fracture of the femoral head) was higher in snowboarders (9 of 30 cases [30.0%]) than in skiers (1 of 8 cases [12.5%]). CONCLUSION: Hip dislocations are much more common in snowboarders than in skiers. Furthermore, the causes and types of hip dislocation differ between snowboarding and skiing.

Adult↗
PubMedDate not supplied

The reliability and validity of knee-specific and general health instruments in assessing acute patellar dislocation outcomes.

BACKGROUND: The most reliable and valid instruments for assessing patient outcome after patellar dislocation have not been identified. HYPOTHESIS: Knee-specific and general health instruments will differ in validity and reliability for patients with patellar dislocation. STUDY DESIGN: Prospective cohort study. METHODS: Subjects consisted of 153 patients with acute patellar dislocation (110 with first-time dislocations and 43 with a history of patellofemoral subluxation or dislocation). We administered the modified International Knee Documentation Committee form, Kujala, Fulkerson, Lysholm, Tegner, Short Form 36, and Musculoskeletal Function Assessment instruments on two separate occasions (test-retest reliability). Validity was assessed by comparing scores of the two groups and by comparing scores of patients with and without recurrent subluxations/dislocations during follow-up. RESULTS: The knee-specific instruments yielded the highest test-retest reliability. The knee-specific and general health instruments identified higher disability levels in the patients with a history of patellofemoral problems than in those with first-time dislocations. The general health instruments identified higher disability levels in patients with patellar dislocation than published norms. The Fulkerson and Lysholm scales were the only instruments to differentiate between patients with and without recurrent subluxations/dislocations. CONCLUSIONS: Knee-specific scales yielded higher reliability coefficients and stronger validity than did general health instruments. Knee-specific, general health, and activity level instruments are complementary and in combination provide a more complete assessment for patients with patellar dislocation.

Adolescent↗