Long-Term Follow up of Correction of Moderate to Severe Deformity with the STAR Ankle Prosthesis

Abstract

Category: Ankle Arthritis Introduction/Purpose: Addressing coronal plane deformity when performing a total ankle arthroplasty (TAA) remains a topic of controversy. While surgeons have become bolder in correcting deformity, long-term follow-up is sparse regarding maintenance of correction and viability of the prosthesis. The purpose of this study is to assess the long-term follow up of the correction of moderate to severe coronal plane deformity with the use of a mobile bearing prosthesis. Methods: Out of a consecutive series of 130 patients who underwent TAA between 2000 and 2009, 43 patients (44 ankles) had at least 100 of tibiotalar coronal plane deformity, with 25 having between 100 and 200 of deformity and 18 having greater than 200. Average age at time of the index surgery was 66 yrs (range 41-79). Initial deformity was 17.90 (range 10-290) in the entire cohort. All patients underwent intraarticular deformity correction with intraoperative soft-tissue balancing as indicated utilizing the STAR prosthesis. Patients requiring realignment osteotomies were performed in a staged fashion prior to undergoing TAA. Results: Seven patients (16%) were available for long-term follow up (avg 13 yrs; range 9-16 yrs) with retention of the original prosthesis, two of which had greater than 200 of initial deformity. Average final tibiotalar deformity was 4.90, with a mean correction of 130(p=0.0001). No additional procedures related to the prosthesis were performed. Eleven patients (12 ankles) were deceased at the time of the study due to unrelated conditions. Of the original cohort, five were deemed failures (2 converted to arthrodesis; 2 underwent component revision; 1 polyethylene fracture) and excluded from long-term follow up. The remaining 20 patients were lost to follow-up, had declined or were unable to participate due to health status. Conclusion: While the low follow-up rate limits the overall generalizability of the results, enduring correction of moderate and severe coronal plane deformity with a mobile bearing prosthesis can be achieved in a cohort of patients traditionally regarded as high-risk. One must be cautious when discussing with patients the utilization of TAA in the setting of moderate and severe coronal plane deformity given the risk of failure. However, provided a well-balanced ankle can be achieved intraoperatively, long-term mobile bearing prosthesis survivorship is achievable.