Correction of Moderate to Severe Coronal Plane Deformity with the STAR™ Ankle Prosthesis

Background: Prior studies have demonstrated a correlation between the degree of preoperative coronal plane deformity and failure following ankle replacement. We reviewed all of our patients who underwent ankle replacement utilizing the STAR (TM) prosthesis from 2000 to 2009 to evaluate the outcome of those with moderate (10 to 19 degrees) and severe (20 degrees or greater) coronal plane deformity. Materials and Methods: Out of 130 consecutive patients, 43 patients had at least 10 degrees of preoperative coronal plane deformity. Twenty-five ankles had 10 to 19 degrees degrees of deformity and 18 ankles had 20 degrees or greater deformity. Average age was 66 years. Average length of followup was 41 (range, 12 to 98) months. Results: Average talar preoperative deformity was 17.9 (range, 10 to 29) degrees, while average initial talar postoperative deformity was 3.5 (range, 0 to 12) degrees. Average final talar postoperative deformity was 4.7 (range, 0 to 14) degrees. Preoperative and final correction of deformity was statistically significant (p < 0.01), but there was no significant difference between initial and final postoperative correction. Overall, recurrence of the preoperative coronal plane deformity occurred in six of 43 patients (14%). All three patients who had deformities over 25 degrees developed recurrences. Correction of the coronal plane deformities was achieved by using intraoperative soft-tissue balancing, including deltoid ligament release in 12 patients and lateral ligament reconstruction in one patient. Deltoid ligament release was found to be necessary for all patients with greater than 18 degrees of yarns plane deformity. Conclusion: Correction of moderate to severe coronal plane deformity with the STAR (TM) prosthesis was achievable with only soft-tissue balancing procedures with predictable results especially for deformities less than 25 degrees.