A controlled, comparative study of a fixed-bearing versus mobile-bearing ankle arthroplasty

Background: Total ankle arthroplasty is available with fixed-bearing (FB) or mobile-bearing (MB) versions, and there is little consensus on the benefits and drawbacks of each type. This study aimed to compare clinical outcomes of statistically paired series of FB and MB versions of the same ankle prosthesis.

Methods: The study was a multicenter retrospective comparison between 2 groups: the FB group of 33 consecutive Talaris cases and the MB group of 33 "paired" Salto cases, selected from a database of 313 consecutive cases to statistically match etiology, age, and preoperative American Orthopaedic Foot & Ankle Society (AOFAS) score. All patients were operated upon with the same operative technique and received identical pre- and postoperative clinical and radiographic assessments. The mean follow-up was 24 months for the FB group and 23 months for the MB group.

Results: There was no statistical difference between results of the 2 groups in terms of accuracy of positioning, clinical and radiographic mobility, and morbidity. The most recent postoperative AOFAS scores were higher for the FB group than for the MB group (P = .05). Radiolucent lines were observed in 4 FB patients versus 13 MB patients (P = .02). Subchondral cysts were noted in 1 FB patient and in 8 MB patients (P = .01).

Conclusion: There was no notable difference in clinical performance of the FB and MB implants with the numbers available. This short-term study demonstrated that FB ankle arthroplasty had results equivalent to, if not better than, MB ankle arthroplasty. Longer follow-up is necessary to determine the success of this new generation of ankle arthroplasty.

Level of evidence: Level III, retrospective case control study.