Fixed Bearing in Primary Total Ankle Replacement Is Associated with Reduced Revision Rates

Abstract

Category: Ankle Arthritis; Ankle Introduction/Purpose: The revision rate for total ankle replacement (TAR) in Australia has decreased over the past 6-years, coinciding with an increased use in fixed bearing prostheses. This study aimed to determine if the use of fixed bearing prostheses or surface coating are associated with lower revision rates. Methods: Data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) included primary cementless TAR procedures performed for any diagnosis from January 2015-December 2021. Procedures were grouped by insert mobility (fixed & mobile) and surface coating (HA & non HA). The time to first revision was summarised using Kaplan-Meier estimates of survivorship, with hazard ratios (HR) obtained from Cox proportional hazards models including age, gender, insert mobility and surface coating. Results: There were 1,865 primary cementless TAR procedures of which 1,467 (78.7%) were fixed bearing and 398 (21.3%) mobile bearing. HA coating was used in 422 (28.8%) of fixed bearing procedures and 336 (84.4%) of mobile bearings. The cumulative percent revision (CPR) at 6 years was 4.1% for fixed bearing and 9.8% for mobile bearing TAR procedures. When the effects of insert mobility and bearing surface were considered separately, fixed bearings had a significantly lower revision rate compared to mobile bearings (HR=0.48), but there was no significant difference between HA and non HA coatings (HR = 1.18). When analysed by insert mobility and surface coating, mobile bearing HA prostheses had a significantly higher revision rate than fixed bearing prostheses with either coating. Conclusion: Analysis of 1,865 primary cementless TAR procedures shows that fixed bearing prostheses have significantly lower rates of revision than mobile bearing prostheses even when adjusting for surface coating.