# Association of antioxidant-added highly cross-linked polyethylene on revision risk: a registry-based study of 198,073 total hip replacements from the Australian Orthopaedic Association National Joint Replacement Registry between 2014 and 2023

## TL;DR

Adding antioxidant to a type of plastic used in hip replacements may reduce the need for revision surgeries after three years, according to a study of over 198,000 cases.

## Contribution

This study provides the first large-scale, registry-based evidence on the long-term performance of antioxidant-added polyethylene in hip replacements.

## Key findings

- THR with antioxidant-added polyethylene had a 37% lower revision rate after 3 years compared to standard polyethylene.
- Revisions due to loosening, wear, and fracture were lower with antioxidant-added polyethylene.
- No difference was found in revisions due to dislocation or infection between the two groups.

## Abstract

Adding antioxidant to highly cross-linked polyethylene (XLPE) is proposed to improve oxidation resistance and decrease wear in total hip replacements (THR), but long-term performance is unknown. We aimed to compare the revision rates of THR using cementless acetabular components where the insert was made of either XLPE with antioxidant (AOXLPE) or XLPE, using data from a large national registry.

The population was THR from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) in the 10-year period 2014–2023 with modular cementless acetabular components and ceramic or metal femoral heads used for osteoarthritis. We compared primary THR using XLPE with antioxidant (AOXLPE) acetabular inserts with XLPE acetabular inserts. The outcome measured was all-cause revision. Cumulative percentage revision (CPR) was calculated using the Kaplan–Meier method, and comparisons made using Cox proportional hazards models.

There were 198,073 THRs, of which 35,309 had AOXLPE inserts. There were 769 and 4,327 revisions with AOXLPE and XLPE inserts, respectively. While there was no early difference, the AOXLPE group had a lower revision rate after 3 years (HR 0.64, 95% confidence interval [CI] 0.48–0.84). When adjusted for multiple factors the AOXLPE group still had a lower revision rate after 3 years (HR 0.63, CI 0.47–0.83). Revisions for loosening, wear-related causes, and fracture were proportionately lower in the AOXLPE group, but no difference was found with revisions for dislocation/instability or infection.

While there was no early difference, THR with AOXLPE acetabular inserts had a lower revision rate after 3 years than XLPE. This suggests a possible clinical benefit using AOXLPE but the difference may, in part, be related to the associated femoral or acetabular components.