Creep and Wear in Vitamin E-Infused Highly Cross-Linked Polyethylene Cups for Total Hip Arthroplasty: A Prospective Randomized Controlled Trial.

BACKGROUND: Aseptic loosening, the most common indication for revision surgery in total hip arthroplasty, can result from osteolysis caused by polyethylene (PE) wear particles. PE wear is increased by age-related oxidation of PE and free radicals emerging during irradiation cross-linking. Diffusion of vitamin E into PE stabilizes free radicals to maintain the biomechanical properties of PE. The purpose of this study was to determine whether vitamin E-infused highly cross-linked PE cups could reduce wear rates. METHODS: We performed a prospective randomized controlled trial, in which 62 patients were allocated to 2 groups: a study group that received a vitamin E-infused highly cross-linked PE (HXLPE/VitE) cup and a control group that received an ultra-high molecular weight PE (UHMWPE) cup. Using radiostereometric analysis, we measured the penetration of the femoral head into the cup 7 days after surgery (baseline) and then again at 6 months and at 1, 2, and 3 years later. RESULTS: Baseline variables did not differ significantly between the groups. At 1, 2, and 3 years after surgery, the HXLPE/VitE cup showed significantly less cumulative penetration (creep and wear) than the UHMWPE cup (p = 0.004, p < 0.0001, and p < 0.0001, respectively). The cumulative penetration after 3 years was 0.200 mm for the HXLPE/VitE cup versus 0.317 mm for the UHMWPE cup (p < 0.0001). From 1 to 3 years after surgery, after creep had stabilized and further penetration was mainly due to wear, the mean penetration increased only 0.04 mm in the HXLPE/VitE cup and 0.116 mm in the UHMWPE cup. CONCLUSIONS: Our results confirm that wear rates over the first 3 years following surgery were lower in HXLPE/VitE cups than in UHMWPE cups. This suggests that HXLPE/VitE cups may prevent osteolysis, implant loosening, and eventually revision surgery. Long-term follow-up data continue to be collected to confirm these findings. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Ten-year follow-up of acute arthroscopic Bankart repair for initial anterior shoulder dislocation in young patients.

INTRODUCTION: Early treatment of initial anterior glenohumeral dislocation in young patients is controversial and the interest of surgery, and notably arthroscopic stabilization, has not been demonstrated. A prospective study was therefore performed to assess (1) short-to-medium-term recurrence rate, (2) functional outcome, and (3) and medium-term osteoarthritis rate. HYPOTHESIS: Early arthroscopic stabilization by anterior capsule-labrum reinsertion after initial anterior shoulder dislocation is associated with low recurrence rate. MATERIALS AND METHODS: Twenty-one patients with initial anterior dislocation were included between June 2002 and February 2004. All patients underwent arthroscopic Bankart repair within 30 days of dislocation. Patients were followed up prospectively, with clinical (Duplay and Constant scores) and radiological assessment (osteoarthritis). RESULTS: There were 5 recurrent dislocations (25%); 2 patients reported sensations of subluxation: i.e., 7 failures (35%). Mean Walch-Duplay score at 10 years was 88±1 (range, 30-100) and mean Rowe score 86±22 (range, 35-100). There was significant internal rotation deficit of one vertebral level between operated and contralateral shoulder (P < 0.005). At 10 years, 3 shoulders (15%) showed Samilson grade 1 centered glenohumeral osteoarthritis. CONCLUSION: Early arthroscopic capsule-labrum reinsertion by the Bankart technique in the month following initial anterior dislocation of the shoulder in patients under 25 years of age provided a low recurrence rate (35%) compared to the literature, including dislocation (25%) and subluxation (10%). Functional outcome was satisfactory, and osteoarthritis rate was low (15% Samilson grade 1). LEVEL OF EVIDENCE: IV, prospective non-comparative study.