Minimum 7-Year Follow-Up of Vitamin E-Diffused and Highly Crosslinked Polyethylene Liners in Total Hip Arthroplasty: Findings from a Prospective, International, Multicenter Study of 977 patients.

BACKGROUND: Vitamin-E diffused highly cross-linked polyethylene (VEPE) acetabular liners for total hip arthroplasty (THA) have shown favorable results in small cohort studies. However, larger studies are warranted to compare its performance to highly cross-linked polyethylene (XLPE) and demonstrate clinical significance in 10-year arthroplasty outcomes. This study compared acetabular liner wear and patient reported outcome measures (PROMs) between patients treated with VEPE and XLPE liners in a prospective, international, multicenter study with minimum 7-year follow-up.

METHODS: A total of 977 patients (17 centers; 8 countries) were enrolled from 2007 to 2012. The centers were randomly assigned to implants. At 1-, 3-, 5-, and 7-year postoperative visits, radiographs, patient reported outcome measures (PROMs), and incidence of revision were collected. Acetabular liner wear was calculated using computer-assisted vector analysis of serial radiographs. General health, disease progression, and treatment satisfaction reported by patients were scored using five validated surveys and compared using Mann-Whitney U tests. At 7-years, 75.4% of eligible patients submitted data.

RESULTS: The mean acetabular liner wear rate was -0.009 mm/year and 0.024 mm/year for the VEPE and XLPE group, respectively (P=0.01). There were no statistically significant differences in PROMs. The overall revision incidence was 1.8% (n=18). The revision incidence in VEPE and XLPE cohorts were 1.92 (n=10) vs 1.75% (n=8), respectively.

CONCLUSION: We found that VEPE acetabular liners in THA led to no significant clinical difference in 7-year outcomes as measured by acetabular liner wear rate, PROMs, and revision rate. While VEPE liners showed less wear, the wear rate for both the VEPE and XLPE liners were below the threshold for osteolysis. Therefore, the difference in liner wear may indicate comparative clinical performance at 7-years, as further indicated by the lack of difference in PROMs, and the low revision incidence.