Midterm Outcomes of a Fixed-Bearing Total Ankle Arthroplasty With Deformity Analysis.

BACKGROUND

We present our results with an INBONE I (Wright Medical, Memphis, TN) prosthesis that have a minimum of 4 to 10 years of follow-up and include a preoperative deformity analysis on outcomes.

METHODS

A consecutive series of 149 patients, from 2007 to 2011, at a single institution were enrolled. Pain and patient-reported function were assessed preoperatively and at yearly follow-ups. We analyzed the data for complications, reoperations, and failures (defined as undergoing revision for exchange or removal of one or both metallic components for any reason). Patients were also grouped according to coronal plane tibiotalar alignment; either ≥10 degrees or <10 degrees, and these outcomes were compared. Our follow-up ranged from 48 to 113 months (average 5.9 years).

RESULTS

There was significant improvement ( P < .05) in the visual analog scale for pain, American Orthopaedic Foot & Ankle Society hindfoot scale, Short Musculoskeletal Function Assessment, and Short Form 36-Item Health Survey scores at most recent follow-up. There were 14 implant failures with overall survivorship of 90.6% (135/149). Reasons for failure included cysts/loosening (7), talar subsidence (4), fractured component (1), impingement pain (1), and infection (1). Seventy-two patients (48.3%) with preoperative coronal plane deformity of ≥10 degrees varus or valgus were compared to 78 patients (51.7%) with <10 degrees deformity. There was no difference in patient outcome scores or revision rates between these patient groups. There was a statistically significant difference ( P = .039) in reoperation rates among patients with ≥10 degrees deformity (22.2%) compared to those without such a deformity (37.7%)

Conclusion

Patients who underwent INBONE I fixed-bearing total ankle arthroplasty demonstrated significant improvement in outcomes at a mean of 5.9 years. Catastrophic talar component collapse did occur (2.7% of cases), but relatively rarely. The patients with preoperative coronal plane tibiotalar deformity had similar pain relief, function, and need for revision of implant components. Despite the presumed shortcomings of the INBONE I's design, this implant showed promising results, with or without deformity, at midterm follow-up with survivorship of 90.6%.

LEVEL OF EVIDENCE: Level III, comparative study.