Low Wear at 10-Year Follow-Up of a Second-Generation Highly Cross-Linked Polyethylene in Total Hip Arthroplasty

Abstract

Background: Characterizations and factors influencing longer term performance of second-generation sequentially irradiated and annealed highly cross-linked polyethylene (HXLPE) are lacking. We evaluated patients who underwent total hip arthroplasty with HXLPE at mean 10-year follow-up for (1) linear and volumetric wear rates, (2) patient and implant characteristics, (3) implant survivorships, and (4) functional scores.

Methods: We evaluated 130 hips (110 patients) that received HXLPE acetabular liners at a single center. The mean age was 56 years (range, 20-79 years), with a mean follow-up of 10 years (range, 8-15). Radiographic linear (millimeters/year) and volumetric (cubic millimeters/year) wear rates were quantified using radiographic analysis. Survivorship was assessed by all-cause and wear-related revision rates. Functional outcomes were assessed by Short Form 12 and modified Harris Hip Scores.

Results: The mean linear wear rate was 0.02 ± 0.03 mm/y, and the mean volumetric wear rate was 12.6 ± 5.3 mm³/y. Younger age had higher volumetric wear (total and yearly, P = .01). Increasing body mass index trended toward higher total and yearly linear (both, P ≤ .09) and volumetric wear (both, P ≤ .07). Ten patients required revisions, with an all-cause survivorship of 92% and a wear survivorship of 100%. The mean modified Harris Hip Scores was 84, and the mean Short Form 12 scores were 46 (physical) and 55 (mental).

Conclusion: We observed low linear and volumetric wear rates for HXLPE at 10-year mean follow-up. Younger age and higher body mass index at the time of surgery may be important patient characteristics influencing long-term wear. These results illustrate the potential for this second-generation HXLPE to be an appropriate long-term total hip arthroplasty interface.

Keywords: THA; highly cross-linked polyethylene; polyethylene wear; survivorship; total hip arthroplasty.