Minimum 10-Y Follow-Up of Vitamin-E-Diffused Highly Crosslinked Polyethylene Liners in Total Hip Arthroplasty: A Comparative Evaluation From a Prospective, International, Multicenter Cohort Study.

ABSTRACT

BACKGROUND: Total hip arthroplasty (THA) is a proven and effective treatment for end-stage osteoarthritis. The success of THA is due in part to highly crosslinked polyethylene (XL) implants. In 2007, a new generation of polyethylene liners entered clinical use. The new liners infused polyethylene with vitamin E and became vitamin E infused polyethylene (EP). The EP liner was hypothesized to prevent the loss of mechanical properties caused by oxidation, extending the lifetime of the implant. This international prospective study aimed to quantify the clinical outcomes of a 977 patient cohort receiving EP and XL liners 10 years after surgery. METHODS: The prospective cohort study began in 2007, including eight countries and 17 centers. The final cohort included 977 patients (EP liner n = 520; XL liner n = 457). Patients were followed preoperatively, postoperatively, and at 1, 3, 5, 7, and 10 years. Each follow-up visit involved clinical evaluation, radiography, and survey collection. The demographics and revisions were also recorded. Mann-Whitney U tests were used to evaluate statistical differences. RESULTS: At 10 years following surgery, 534 patients were eligible for follow-up. Of those eligible, 352 patients returned for clinical evaluation (65.9% eligible; 36.0% overall). No statistical differences were found (P > 0.05) in the demographics of the followed-up cohort. The linear wear rates were 0.00338 mm/year for EP liners and 0.0236 mm/year for XL liners using individual regression (P < 0.0001). No significant difference was observed in wear rates using cohort regression. Similarly, surveys suggested no significant outcomes between the EP and XL liner cohorts. The overall incidence of revision was 2.3% for EP and 2.0% for XL liners. CONCLUSIONS: The EP liner demonstrated significantly lower wear than its XL counterparts at 10 years after implantation. Results are promising, as vitamin E polyethylene may improve the lifetime performance of THA implants and ensure that arthroplasty innovations reflect the changing patient population.