Femoral Head Penetration Rates and Oxidation of Highly Crosslinked Polyethylene Hip Liners Implanted More Than 10 Years

Tabitha Derr; Daniel W MacDonald; Arthur L Malkani; Gregg Klein; Steven M Kurtz

doi:10.1016/j.arth.2024.05.024

Femoral Head Penetration Rates and Oxidation of Highly Crosslinked Polyethylene Hip Liners Implanted More Than 10 Years

J Arthroplasty. 2024 May 14:S0883-5403(24)00457-1. doi: 10.1016/j.arth.2024.05.024. Online ahead of print.

Authors

Tabitha Derr¹, Daniel W MacDonald², Arthur L Malkani³, Gregg Klein⁴, Steven M Kurtz²

Affiliations

¹ Implant Research Core, Drexel University, Philadelphia, PA,. Electronic address: td627@drexel.edu.
² Implant Research Core, Drexel University, Philadelphia, PA.
³ University of Louisville, Louisville, KY.
⁴ Hackensack University Medical Center, Hackensack, NJ.

PMID: 38754708
DOI: 10.1016/j.arth.2024.05.024

Abstract

Introduction: Highly cross-linked and thermally stabilized polyethylene (HXLPE) was introduced to improve wear in total hip arthroplasty (THA), with manufacturers implementing different thermal treatments to reduce oxidation. It is important to understand how long-term time in vivo affects the wear of these materials. The purpose of this study was to investigate the wear and oxidative performance of first-generation HXLPE hip inserts implanted for greater than 10 years and compare annealed and remelted HXLPE formulations.

Methods: There were 49 THA liners retrieved during routine revision surgery as part of an IRB approved implant retrieval program. Penetration rates for the liners were calculated as the difference between the thickness of the unloaded and loaded regions divided by implantation time. Oxidation indices for the rim, locking mechanism, articulating surface, and backside regions were measured using Fourier-transform infrared spectroscopy according to ASTM 2102. Mann-Whitney U Tests were used to determine the statistical difference between annealed and remelted components.

Results: The cohort had an average implantation time of 13.1 ± 2.6 years for annealed and 12.1 ± 1.7 years for remelted components. The components were revised most often for polyethylene wear, instability, and loosening. The penetration rate averaged 0.0177 ± 0.014 mm/year for annealed components and 0.015 ± 0.022 mm/year for remelted components. Penetration rates did not differ between the remelted and annealed cohorts (P = 0.28). Oxidation indices were found to be significantly higher in the annealed cohort for all regions of interest (P < 0.001).

Conclusion: Oxidation was found to be higher in the annealed HXLPE; however, this does not seem to be associated with greater wear, as we found the average penetration rate for the cohort was low, and the penetration rates were similar between the annealed and remelted cohorts.

Keywords: Total hip arthroplasty; polyethylene; retrieval studies; revision reasons.