Clinical Outcome and Fusion Rate Following Simultaneous Subtalar Fusion and Total Ankle Arthroplasty

Background: Patients with arthritis or severe dysfunction involving both the ankle and subtalar joints can benefit from tibiotalocalcaneal (TTC) arthrodesis or total ankle replacement and subtalar fusion. TTC fusion is considered by many as a salvage operation resulting in a stiff ankle and hindfoot, considerably limiting global foot function. With the evolution of prosthetic design and operative techniques, total ankle replacement (TAR) has become a reasonable alternative to arthrodesis. The aim of this study was to investigate the fusion rate of the subtalar joint in patients simultaneously treated with total ankle replacement (TAR) and subtalar joint fusion. Methods: This study included 25 patients who underwent primary TAR and simultaneous subtalar fusion between May 2011 and November 2014. Sixteen males (64%) and 9 females (36%) were enrolled with a mean age of 58 years (25-82). Patients were clinically assessed preoperatively and at 6 and 12 months postoperatively. Total follow-up time was 24.2 ± 11.6 months. Radiographic examination included a postoperative computed tomographic (CT) scan obtained 12 months after surgery. Three surgeons independently reviewed the CT scans and interobserver reliability was calculated. Functional scores were also assessed. Results: At 12 months postoperatively, the subtalar fusion rate in patients treated with TAR and simultaneous subtalar fusion was 92%. There was a statistically significant increase in American Orthopaedic Foot & Ankle Society ankle/hindfoot score from 27.9 to 75.1. Ankle range of motion significantly increased from 12 to 32.8 degrees. Additionally, there was a statistically significant decrease in visual analog scale pain score from 8.6 to 2.1. Conclusions: TAR and simultaneous subtalar joint fusion were reliable procedures for the treatment of ankle and subtalar joint arthritis. Furthermore, CT scans showed an excellent reliability among orthopedic surgeons in determining the degree of successful fusion of subtalar arthrodesis. Level of Evidence: Level IV, case series.