# Seventeen-year outcomes for a contemporary total hip resurfacing prosthesis in Australia: an analysis of registry data with comparison to best performing conventional and most prevalent resurfacing prostheses

## TL;DR

This study compares the long-term success of a hip resurfacing implant in Australia with other implants, finding it performs well in younger patients but has some risks.

## Contribution

The study provides 17-year survivorship data for a contemporary hip resurfacing prosthesis and compares it with benchmarks using registry data.

## Key findings

- The study HRA had 94% 17-year survivorship, comparable to a benchmark HRA but lower than conventional prostheses.
- Younger patients (<55) had similar revision risks to conventional prostheses and better outcomes than the benchmark HRA.
- Fracture and metal-related issues were leading causes of early and late revisions for the study HRA.

## Abstract

This study addresses survivorship up to 17 years for the hip resurfacing arthroplasty (HRA) system most commonly used in Australia at present. Here we compare overall and age-stratified revision rates of the study HRA to a benchmark HRA and the five conventional prostheses with the lowest 10-year cumulative percent revision (5THA) in the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). We further compare outcomes for the resurfacing target cohort of men under 65 years. Finally, we compare revision diagnoses for the study prosthesis and benchmarks.

AOANJRR data were analysed for osteoarthritis patients who underwent total hip arthroplasty, to the end of 2023. Using Cox proportional hazards models, we compared revision rates (estimated using Kaplan–Meier survival curves with 95 % confidence intervals) across the three groups. Femoral head sizes <50 mm for HRA and <32 mm for 5THA were excluded. Cumulative incidence plots were used to compare revision diagnoses.

For the study HRA, the 17-year survivorship was 94 %, with revision risks comparable to the benchmark HRA but inferior to 5THA. For patients under 55 years, revision rates were comparable to those of 5THA and superior to the benchmark HRA. Revision risks were not significantly different between the three groups for men under 65 (95 % survivorship for the study HRA). Fracture and metal-related pathology were the most likely reasons for early and late revision respectively, while loosening and fracture were the most common revision diagnoses for the benchmark HRA and 5THA respectively.

The study HRA achieved similar survivorship to the benchmark HRA and 5THA in men <65 years, but inferior to 5THA overall. Outcomes were best for younger patients. Adverse metal reactions remain a concern, with longer follow-up essential to assess their impacts and other trends in revision diagnoses.