Subtalar Fusion Rate in Patients With Previous Ipsilateral Ankle Arthrodesis

Background: Isolated subtalar arthrodesis is generally successful, with reported fusion rates of 84% to 100%. However, alteration of subtalar joint mechanics and talar body vasculature after ankle fusion may negatively influence subsequent ipsilateral subtalar joint fusion. Because there is very limited information on the subtalar fusion rate in patients with previous ipsilateral ankle fusion, the purpose of this study was to describe fusion rates in subtalar joint arthrodesis with and without preexisting ankle fusion in a large consecutive series of primary subtalar arthrodesis cases. Methods: All primary subtalar fusions performed between January 2000 and December 2010 were reviewed. Thirteen of 151 consecutive cases were in patients with existing ipsilateral ankle fusions. All patients were evaluated for clinical and radiographic evidence of nonunion at follow-up, and fusion rates in the groups with and without previous ipsilateral ankle fusion were compared. Results: Five nonunions occurred in the 13 cases with prior ipsilateral ankle arthrodesis, a 61.5% fusion rate. Twelve nonunions were identified in the 138 cases without prior ankle arthrodesis, a significantly higher fusion rate of 91.3% (P = .007). Conclusion: In our series, the subtalar fusion rate in patients with previous ipsilateral ankle arthrodesis was significantly lower than that for subtalar arthrodesis in the absence of ipsilateral ankle arthrodesis. Level of Evidence: Level III, retrospective comparative study.