The Effect of Bearing Surface On the Survival of Cementless and Hybrid Total Hip Arthroplasty: An Analysis of Linked National Joint Registry and Hospital Episode Statistics Data

Background: Crosslinked polyethylene-based bearings have led to marked improvements in total hip arthroplasty (THA) survival. Antioxidant highly crosslinked polyethylene bearings are the latest addition to the bearing options. Previous reports were limited by low numbers and short follow-up in this category therefore limiting comparisons. Methods: We combined the UK National Joint Registry data set with polyethylene manufacturing characteristics to classify polyethylene as crosslinked (XLPE) or conventional polyethylene. The Hospital Episode Statistics data set was used to link ipsilateral surgical procedures for the treatment of periprosthetic hip fractures. The effect of bearing surface on THA survival was analyzed through estimating cause-specific cumulative incidence functions to allow for competing risks. This was followed by regression analysis that fitted a Fine-Gray proportional subdistribution hazards model for reoperation. Results: A total of 696,013 THAs and 17,468 reoperations were included in this analysis. Average follow-up time was estimated to be between 4.83 and 9.64 years depending on the bearing combination while the maximum follow-up was 19.1 years across all bearings. The estimated cause-specific cumulative incidence functions allowing for competing risks revealed that Ceramicised Metal on XLPE (CMoXLPE) and Ceramic on Antioxidant XLPE (CoAoXLPE) had the lowest probability of reoperation by the end of the follow-up period. The regression analysis (all ages) with Metal on Polythelene (MoP) as the reference bearing adjusted for age, sex, and stem fixation showed CMoXLPE to be associated with the lowest risk of revision for any reason (HR = 0.64, 95% CI = 0.58-0.72) followed by CoAoXLPE XLPE (HR 0.65, 95% CI = 0.57-0.74). Conclusion: This analysis, which includes fixations as well as revisions in defining reoperation for periprosthetic fracture, covers a longer follow-up period compared with earlier reports. Regression analysis in a model including all ages, all bearings, with MoP as the reference revealed the lowest risk of revision for any reason in THAs using CMoXLPE and CoAoXLPE. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.