Midterm Results of AAA Ankle Arthroplasty

Abstract

Background: Outcome reports for Alpha Ankle Arthroplasty (AAA), a third-generation implant relying on a mobile bearing design for total ankle replacement, are sparse. This retrospective study evaluated the midterm survivorship, clinical, and radiologic outcomes after implantation of this implant.

Methods: For 64 patients who received 65 Triple A ankle implants between 2009 and 2020, implant survival was calculated using the Kaplan-Meier curve. Clinical outcomes were evaluated by measuring the range of motion, stability, Western Ontario and McMaster Universities Osteoarthritis Questionnaire score (WOMAC), and American Orthopaedic Foot & Ankle Society ankle-hindfoot score (AOFAS). The average pain level and satisfaction with the postoperative result were rated on a numeric rating scale (0-10). Additionally, radiologic analysis was performed using anteroposterior and lateral radiographs and tibiotalar alignment was assessed.

Results: The implant-survival rate was 61.5% at a mean follow-up of 8.2 years. Twenty-five patients (38.5%) required revision surgery (average time to revision, 3.1 years, 95% CI 2.1-4.1 years). For patients without revisions, the average range of motion in dorsiflexion and plantarflexion were 3.6 ± 4.2 degrees and 21.9 ± 7.8 degrees, respectively. The mean WOMAC and AOFAS scores were 44.7 ± 47.5 and 75.1 ± 14.0, respectively. The average pain and subjective satisfaction scores were 2.0 ± 1.7 and 8.5 ± 1.9, respectively. Mean alignment values did not differ significantly for patients who required revision surgery.

Conclusion: We found a high revision rate with use of the AAA. However, patients who did not require revision surgery had, on average, high satisfaction and good functional outcomes.

Level of evidence: Level IV, case series.

Keywords: ankle arthritis; ankle arthroplasty; clinical outcomes; survivorship.