Up to 18-Year Follow-Up Wear Analysis of a First-Generation Highly Cross-linked Polyethylene in Primary Total Hip Arthroplasty

Background: The advent of highly cross-linked polyethylene (HCLPE) has significantly improved total hip arthroplasty (THA) survivorship. HCLPE has been shown to improve wear properties in midterm outcomes when compared to traditional polyethylene liners; however, there is a paucity of studies evaluating long-term outcomes. Thus, the aims of this study is to report on the longest-to-date follow up of a specific first-generation HCLPE liner, and to determine if there is a change in the annual wear rate over time.

Methods: 41 patients (43 hips), who were previously reported on in a midterm study were included in this long-term follow-up study. Patients in this cohort all received THA between January 1999 and August 2004 using a specific HCLPE liner. Only patients who had follow-up radiographs greater than 10 years were included in this review. Anterior-posterior radiographs were reviewed for total penetration (mm) and wear rates (mm/year) using the Roman software V1.70 (Figure 1). All descriptive and inferential statistics were conducted using SPSS v21. A p-value

Results: The average patient age and BMI at time of surgery was 57.1 years and 25.8kg/m², respectively. The average follow-up of this cohort of patients was 14.3 years (range 12 to 18 years). The mean wear rate in our cohort was 0.140 mm/year (SD: 0.05mm/year). Average total wear was 1.78 mm (SD: 0.65mm) over the study period.

Conclusions: Our study demonstrates that the long-term wear rates associated with HCLPE liners continues to match rates published in midterm studies. Previously, we have reported that this cohort had an average annual wear rate of 0.122mm/year over 10-years. This most recent report demonstrates a similar wear rate with up to 18-year follow-up. While these results are promising, more robust long-term follow-up on newer generation HCLPE liners may be necessary to reaffirm our results.