Abstract
Data is scant on the critical question of whether patients with endstage ankle arthritis are better served by a fusion or a replacement.
The STAR trial, a prospective case control study, comparing safety and efficacy of STAR ankle replacement at 24 months for 158 replacements and 66 fusions:
This FDA trial showed the STAR ankle replacement had better function, equivalent pain relief and a higher rate of complications and secondary procedures as ankles treated with fusion. A separate prospective cohort comparison of 200 ankle replacements vs. 94 ankle fusions performed by the collaborative consortium of Canadian Orthopaedic Foot and Ankle Surgeons (COFAS) suggests similar patient oriented outcomes at 24 months. Patients' self-assessment questionnaires do not show significant differences between the two groups.
The main medium/long-term concerns with ankle replacement remain component subsidence (especially talar subsidence) and polyethylene wear. Forces across the ankle are considerable, and the orientation of those forces to the underlying trabecular structure are a concern. Whether 2 or 3 part ankles will provide better bearing wear results remains unknown. With older designs, at 10 years the Swedish registry found approximately 60% survivorship. This registry has also shown better survivorship in patients with rheumatoid disease and with increased surgeon experience. More recent results related to the Hintegra and AES components show better midterm (5 year) revision rates in selected surgeons hands, than seen with older designs.
A large meta-analysis of ankle fusion and replacement published data by Haddad et al reported a mean nonunion rate of 10%. The main long-term concerns with ankle fusion are limitations of motion, and the development of premature arthritis in adjacent foot joints. In a study of an average of 9 year outcome of the Agility ankle replacement suggested that the incidence secondary arthritis is halved by replacement as compared to fusion.
