Comparative study of the Nottingham Foot and Ankle Unit outcomes of the Scandinavian Total Ankle Replacement (STAR) and the mobility total ankle replacement

M. Raglan, A. Taylor, S. Dhar

Introduction: Total ankle replacement is a recognised treatment for disabling end stage ankle arthritis and an alternative to arthrodesis, although results are not yet comparable to other joint replacements. This has stimulated a constant evolution in design of implants and instrumentation. The Nottingham Foot and Ankle Unit used the STAR until 2005, when it switched to Mobility, due to the perceived advantages of less bone resection, improved instrumentation and potentially less polyethylene insert wear. The aim of this study is to report the unit’s results and review the different outcomes between the two ankle replacements used.

Methods: A retrospective analysis of all total ankle replacements carried out by the foot and ankle unit at Nottingham City Hospital between March 1999 and June 2013. Post operative complications, associated reoperations and revisions were recorded. The American Orthopaedic Foot and Ankle Score (AOFAS), Foot Function Index (FFI), European five dimension quality of life scores (EQ-D5) and patient satisfaction was independently assessed at each follow up visit. Other ankle replacements or those performed elsewhere or with less than 12 month follow up were excluded.

Results: 162 Mobility and 148 STARs’ were assessed. The mean follow up was 7 years (1-13yrs,) STAR and 3.5 years (1- 8 yrs) Mobility. Post-operative complication rate of 15% STAR and 13% Mobility, associated operation rate of 15% STAR and 10% Mobility with revision rate of 19% STAR at 13 years and 4.3 % Mobility at 8 years. Both STAR and Mobility groups showed improvements in AOFAS, FFI, EQ-D5 and patient satisfaction, but there were no significant differences between the two groups.

Conclusion: This is one of the largest comparative series of total ankle replacements and shows that patient satisfaction, pain and function is improved. The Mobility total ankle replacement had fewer revisions and complications compared to STAR.