Obesity, age, sex, diagnosis, and fixation mode differently affect early cup failure in total hip arthroplasty: a matched case-control study of 4420 patients

Studies about the influence of patient characteristics on mechanical failure of cups in total hip replacement have applied different methodologies and revealed inconclusive results. The fixation mode has rarely been investigated. Therefore, we conducted a detailed analysis of the influence of patient characteristics and fixation mode on cup failure risks.

Long-term outcome after structural failure of rotator cuff repairs

BACKGROUND: In a previous study, twenty consecutive patients with a rerupture of the rotator cuff, as documented with magnetic resonance imaging, were found to have significantly less pain and better function and strength, compared with the preoperative state, at 3.2 years postoperatively. It was the purpose of this study to determine the clinical and structural outcomes of these reruptures in the same twenty patients after a longer period of follow-up. METHODS: At a mean of 7.6 years postoperatively, the twenty patients were reexamined clinically and with standard radiographs and magnetic resonance imaging with use of the same clinical, radiographic, and magnetic resonance imaging criteria as were utilized in the review at 3.2 years. The mean age at the time of final follow-up was sixty-six years. RESULTS: Nineteen of the twenty patients continued to be either very satisfied or satisfied with the outcome. The relative Constant score averaged 88% and was not significantly different from the score at 3.2 years, which averaged 83%. The mean scores for pain, function, and strength also had not changed significantly. Overall, the twenty reruptures had not increased in size, and eight of them had healed structurally at the time of the 7.6-year follow-up. Seven of these eight reruptures had been of the supraspinatus tendon only, and seven had been smaller than 400 mm(2) at 3.2 years. Twelve reruptures persisted, and five were larger than the preoperative tear. Fatty infiltration of the infraspinatus muscle progressed significantly (p = 0.015) and the acromiohumeral distance decreased significantly (p = 0.006) between the two follow-up periods. Neither fatty infiltration of the supraspinatus and subscapularis muscles nor glenohumeral osteoarthritis progressed significantly. CONCLUSIONS: At an average of 7.6 years, the clinical outcomes after structural failure of rotator cuff repairs remained significantly improved over the preoperative state in terms of pain, function, strength, and patient satisfaction. Overall, the reruptures that had been present at 3.2 years did not increase in size. We also found that reruptures of the supraspinatus that had been smaller than 400 mm(2) had the potential to heal.

Efficiency of arthroscopic lysis and lavage for internal derangement of the temporomandibular joint correlated with Wilkes classification

OBJECTIVES: To compare the outcome of arthroscopic lysis and lavage of TMJ with internal derangement of Wilkes stages II, III, IV, and V. STUDY DESIGN: Arthroscopic lysis and lavage was performed in 45 TMJ of 39 patients with internal derangement. The cases were divided into 4 groups corresponding to Wilkes stages II, III, IV, and V. Two parameters were compared pre- and postoperatively: pain and mouth opening. Statistical significance was determined using the chi(2) test. RESULTS: Overall success rate was 86.7% (Wilkes stage II 90.9%, Wilkes stage III 92.3%, Wilkes stage IV 84.6%, Wilkes stage V 75%). There were no statistically significant differences between the success rates for Wilkes stages II, III, IV, and V. CONCLUSION: Arthroscopic lysis and lavage should be performed as a standard operation for internal derangement of the TMJ after failure of conservative treatment in all Wilkes stages.

Treatment of joint prosthesis infection in accordance with current recommendations improves outcome

BACKGROUND: Recently recommended treatment modalities for prosthetic joint infection (PJI) were evaluated. METHODS: A retrospective cohort analysis of 68 patients with PJI of hip or knee who were treated from 1995 through 2004 was conducted at the University Hospital Bern (Bern, Switzerland). RESULTS: A 2-stage exchange was the most frequent (75.0%) surgical strategy, followed by retention and debridement (17.6%), 1-stage exchange (5.9%), and resection arthroplasty or suppressive antimicrobial treatment (1.5%). The chosen strategy was in 88% agreement with the recommendations. Adherence was only 17% for retention and debridement and was 0% for 1-stage exchange. Most PJIs (84%) were treated with an adequate or partially adequate antimicrobial regimen. Recurrence-free survival was observed in 51.5% of PJI episodes after 24 months of follow-up. The risk of treatment failure was significantly higher for PJI treated with a surgical strategy other than that recommended (hazard ratio, 2.34; 95% confidence interval, 1.10-4.70; P = .01) and for PJIs treated with antibiotics not corresponding to recommendations (hazard ratio, 3.45; confidence interval, 1.50-7.60; P = .002). Other risk factors associated with lack of healing were a high infection score at the time of diagnosis (hazard ratio, 1.29; 95% confidence interval, 1.10-1.40; P < .001) and presence of a sinus tract (hazard ratio, 2.35; 95% confidence interval, 1.10-5.0; P = .02). CONCLUSIONS: Our study demonstrates the value of current treatment recommendations. Inappropriate choice of conservative surgical strategies (such as debridement and retention) and inadequate antibiotic treatment are associated with failure.

Finite element analysis predicts experimental failure patterns in vertebral bodies loaded via intervertebral discs up to large deformation

Vertebral compression fracture is a common medical problem in osteoporotic individuals. The quantitative computed tomography (QCT)-based finite element (FE) method may be used to predict vertebral strength in vivo, but needs to be validated with experimental tests. The aim of this study was to validate a nonlinear anatomy specific QCT-based FE model by using a novel testing setup. Thirty-seven human thoracolumbar vertebral bone slices were prepared by removing cortical endplates and posterior elements. The slices were scanned with QCT and the volumetric bone mineral density (vBMD) was computed with the standard clinical approach. A novel experimental setup was designed to induce a realistic failure in the vertebral slices in vitro. Rotation of the loading plate was allowed by means of a ball joint. To minimize device compliance, the specimen deformation was measured directly on the loading plate with three sensors. A nonlinear FE model was generated from the calibrated QCT images and computed vertebral stiffness and strength were compared to those measured during the experiments. In agreement with clinical observations, most of the vertebrae underwent an anterior wedge-shape fracture. As expected, the FE method predicted both stiffness and strength better than vBMD (R2 improved from 0.27 to 0.49 and from 0.34 to 0.79, respectively). Despite the lack of fitting parameters, the linear regression of the FE prediction for strength was close to the 1:1 relation (slope and intercept close to one (0.86 kN) and to zero (0.72 kN), respectively). In conclusion, a nonlinear FE model was successfully validated through a novel experimental technique for generating wedge-shape fractures in human thoracolumbar vertebrae.

Prevention of cement leakage into the hip joint by a standard cement plug during PFN-A cement augmentation: a technical note.

Medial penetration of the helical blade into the hip joint after fixation of trochanteric fractures using the proximal femur nail antirotation (PFN-A) is a potential failure mode. In low demand patients a blade exchange with cement augmentation may be an option if conversion to total hip arthroplasty is unfeasible to salvage the cut-through. This article describes a technique to avoid intraarticular cement leakage using a cement plug to close the defect in the femoral head caused by the cut-through.