Clinical comparison of two mobile bearing total ankle arthroplasties

We compared the long term outcomes and clinical survival of two mobile bearing ankle replacements; the Zenith ankle prosthesis and the Salto ankle prosthesis, in a demographically similar group of consecutive patients from a single, non designer centre.

Between December 2010 and February 2017, 118 consecutive Zenith prosthesis and 41 consecutive Salto prostheses were implanted in a total cohort of 153 patients. Demographic and clinical outcome measures were collected. The end point of the study was failure of the implant requiring revision of one or more of the components. Kaplan Meier survival tables were generated.

25 patients (28 ankles) died during follow-up, but none required revision. Of the surviving 128 patients (131 ankles; 91 Zenith, 40 Salto), mean follow-up was 10.1 years (6.5 - 14.6 years) for the Zenith and 8.4 years for the Salto (5.0 - 11.0 years). A total of 11 implants (9.3%) failed for the Zenith and 6 implants (14.6%) failed for the Salto, thus requiring revision. The implant survival at ten years, using revision as an endpoint, was 90.5% (CI 84.8-94.8% for Zenith and 80.7% (CI 65.1-92.9%) for Salto. The three commonest reasons for revision were aseptic loosening, recurrent mal-alignment and pain.

Our results show no significant differences in clinical outcomes or long term survival rates across the two mobile bearing devises (p = 0.369). Survival rates are comparable with those reported in the literature.