Arthroscopic ankle arthrodesis: Factors influencing union in 39 consecutive patients

Background: Arthroscopic ankle arthrodesis is an effective alternative to open techniques with established advantages in select patient populations. The purpose of this study was to evaluate patients who had arthroscopic ankle arthrodesis for end-stage arthritis with minimal to no deformity of the ankle and to report factors influencing union. Methods: Thirty-nine consecutive patients had arthroscopic ankle arthrodesis between 1994 and 2003. Clinical records and radiographs were retrospectively reviewed to evaluate variables that could predispose patients to nonunion. Union outcomes were correlated with etiology of arthritis, ankle deformity, medical comorbidities, and the use of demineralized bone matrix or platelet-rich plasma. Arthroseopic ankle arthrodesis was accomplished with a consistent technique using crossed transmalleolar cannulated screw fixation. Results: Thirty-four of 39 patients (87.2%) achieved radiographic and clinical union. The average time to fusion was 47 (range 37 to 70) days. Poor bone quality and inherent positional ankle deformity were identified as risk factors for nonunion. Patients who smoked, had diabetes mellitus, peripheral neuropathy, or other medical comorbidities attained ankle union in nearly all cases. In obese patients, there was an observed trend towards ankle nonunion (relative risk 5.81, p = 0.049, Fisher's Exact test). The addition of demineralized bone matrix or platelet-rich plasma did not improve the rate of ankle union. Aside from nonunion, 10 patients developed minor complications. Conclusion: Arthroscopic ankle arthrodesis achieves high union rates, facilitates short time to union, and permits rapid patient mobility. Careful patient selection is important for the procedure. Synthetic allograft or platelet-rich plasma did not enhance the fusion rate. Obese patients showed a trend towards nonunion in this series.