Abstract
Introduction
The Mobility™ prosthesis [Depuy] is the most extensively used TAR in the UK, though there are few published results. We present our complete experience of the Mobility prosthesis in a diverse population.
Methods
From March 2005 to December 2009, 84 consecutive Mobility ankle replacements were performed by the senior author, in 79 patients (28 female, 51 male) with mean age 64.5 years (43–80). This complete cohort included the first and last cases with this implant. Mean follow-up was 50.1±18.2 months (range 14–86).
Patients with ankle replacements in situ, were reviewed clinically and radiologically. Clinical outcome measures were: AOFAS score, MOXFQ (adapted for the ankle), and VAS for pain. Post-operative radiographs were reviewed to assess component position and examine for zones of lucency.
Results
At final review, 1 patient had died (unrelated), 13 had been revised as follows:
Arthrodesis 7
Further TAR 2
Talus only revised 1
Tibia only revised 1
Amputation 2 (one for an unrelated problem)
Exchange of bearing had been carried out in 4.
Intra-operative malleolar fractures occurred in 4.8% and were internally fixed.
62 patients attended for clinical review and 8 completed postal questionnaires.
At follow up:
Mean AOFAS hindfoot score was 72.4±17.5 (0–100).
Mean MOXFQ scores were:
Walking/Standing 40.8±28.4
Pain 31.6±20.8
Social 23.1±23.0.
Mean VAS 2.7±2.3.
Survival of the implant was:
91.7 (CI 83.4–96.0) at 2 years
89.2 (CI 80.2–94.2) at 3 years
84.1 (CI 73.4–90.8) at 4 years
84.1 (CI 73.4–90.8) at 5 years
78.9 (CI 62.6–88.7) at 6 years
Conclusion
This study is a complete review and our failure rate is comparable to other publications. Early failures included some poor case selections with large pre-operative deformity and reflects the initial period of the learning curve of TAR. Longer term follow up is needed to evaluate for ongoing failures and monitor progressive radiolucency.
