Revision Arthrodesis of the Subtalar Joint

CATEGORY: Hindfoot INTRODUCTION/PURPOSE: Subtalar arthrodesis is an invaluable tool in managing arthritis, deformity, and muscular imbalance of the hindfoot. However, failed arthrodesis is complicated by bone necrosis, sclerosis with loss of bone, less than ideal biologic settings, and the literature reports a high rate of non-union. The aim of this study was to review all subtalar arthrodeses performed within a single institution, and specifically describe the management of non-union. METHODS: 492 consecutive subtalar arthrodesis cases were retrospectively analyzed between October 2001 and July 2013. From the primary arthrodesis group 91 (18%) were treated for subtalar coalition (100% arthrodesis), and were excluded to better depict the arthrodesis rate; the remaining 401 patients were treated primarily for post-traumatic arthritis. Pertinent demographics, comorbidities, and clinical notes were all retrieved through the electronic medical record and radiographs were reviewed through a PACS system. RESULTS: 49 patients with a mean age of 49 years (range 23 - 80) presented with subtalar non-union (overall rate 10%, adjusted rate 18%). 41 (84%) underwent revision at a mean of 16.2 months (range 2.8 - 57.1) from the index arthrodesis. The rate of revision arthrodesis was 78%, 21/30 (70%) in situ arthrodeses, 7/7 bone block arthrodesis (p=.028), and 4/4 triple arthrodesis (p=.028). Arthrodesis was present at a mean of 3.4 months (range 1.6 - 7.6). 4/9 (44%) of the recurrent nonunions elected to abstain from surgery. Of the 5 remaining patients, 2/5 had a successful third attempt at arthrodesis, 1/5 had an additional nonunion followed by a successful fourth attempt at arthrodesis, 1/5 had a successful tibiotalocalcaneal arthrodesis, and 1/5 required a below-knee amputation. CONCLUSION: Risk factors identified for non-union were post-traumatic arthritis, ipsilateral ankle arthrodesis, and individual patient factors (smoking, diabetes, and infection). Different methods of screw fixation were not found to be significantly different between the fused and nonunion groups. Despite directed management to obtain rigid fixation and adequate compression, the rates of subtalar arthrodesis from primary (82%), revision (78%) and secondary revision (60%) cases were very poor with the exception of the group which underwent a bone block arthrodesis (100%, p=.028).