Randomised Prospective Trial Comparing the Salto Talaris Fixed-Bearing and Salto Mobile-Bearing Total Ankle Replacement

Category: Ankle Arthritis; Ankle Introduction/Purpose: Comparative studies examining Fixed-Bearing (FB) and Mobile-Bearing (MB) Total Ankle Replacement (TAR) designs have demonstrated similar results and successful long-term outcomes for both. To date there has been no study directly comparing FB and MB designs of the same prosthesis. We present the first randomised prospective trial comparing patient satisfaction, functional outcomes and radiographic results of the Salto Talaris Fixed-Bearing and the Salto Mobile-Bearing Total Ankle Replacement in the treatment of end-stage ankle arthritis. Methods: A total of 106 adult patients with end-stage ankle arthritis were enrolled in the study between November 2014 and October 2021 with similar demographic comparison. Prospective patient-reported outcomes and standardised weightbearing ankle radiographs were performed preoperatively, at 6 weeks, 6 months and 12 months post-operatively, followed by yearly intervals. Foot Function Index, Revised Foot Function Index, 12-Item Short Form Survey and Total Ankle Joint Replacement Questionnaire were used for patient reported scoring. All surgeries were performed by a single non-design orthopaedic foot and ankle specialist with experience in over 200 Salto and Salto Talaris TAR prior to the study. Radiographs were examined independently by two clinicians. Complete patient data and radiographs were available for 101 patients with an average follow up of 3 years. Results: Both groups demonstrated statistically significant improvement from preoperative evaluation to most recent follow up with no statistically significant difference between the two groups in all outcome measures. Radiographic incidence of subchondral cyst formation was 17.4% and 49.1% for FB and MB, respectively. Talar subsidence occurred in 8.7% and 18.2% of FB and MB, respectively. Implant subluxation was observed in 1.8% of MB TAR. Two patients required revision, one from each cohort reflecting a revision rate of 2.2% for FB and 1.8% for MB TAR. Conclusion: Our study demonstrates a higher than previously reported rate of subchondral cyst formation in the MB TAR and comparatively higher talar subsidence in the MB TAR vs FB however this did not correlate with clinical outcome measures which were favourable for both groups.