Fusion Rates of Ankle Arthrodesis with Anterior Plate Fixation Based on Computerized Tomography and Clinical Outcomes

CATEGORY: Ankle; Ankle Arthritis INTRODUCTION/PURPOSE: Ankle arthrodesis is a common treatment for tibiotalar joint arthritis and anterior plate fixation is often utilized. Prior series reporting on anterior plate fixation for ankle arthrodesis have been relatively small and none have exclusively used post-operative computerized tomography (CT) scans for confirmation of fusion. The purpose of this study was to determine radiographic and clinical outcomes of patients who underwent ankle arthrodesis with anterior plate fixation. The primary outcome of the study was whether or not successful arthrodesis was obtained based on a quantitation of the fusion mass on CT scan. Furthermore, correlation between ankle fusion and clinical outcomes along with complications were evaluated. METHODS:: Adult patients who underwent ankle arthrodesis with anterior plate fixation (including straight anterior and anterolateral plates) were eligible for this study. Charts were retrospectively reviewed and data was collected in a prospective fashion. In total, 102 patients were included in the study and obtained a CT scan at least 90 days after surgery. The primary outcome was tibiotalar fusion, defined as osseous bridging of 50% or more of the tibiotalar joint based on CT scan reviewed by a single musculoskeletal radiologist. Secondary outcomes included patient reported outcome measures (PROMs): the American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot Scale, Foot function index (FFI), Visual analog scale (VAS) pain score, and Coughlin satisfaction scale. Additional surgeries and complications including nonunion, painful hardware, tibial stress fractures, wound dehiscence, deep infection, superficial infection, and nerve injury/deficit were recorded. RESULTS: Post-operative CT scans demonstrated tibiotalar fusion in 85 of 102 (83.3%) patients. Of the 17 (16.7%) patients who were classified as non-unions, only 8 (47.1%) of them were symptomatic. Five patients (3.9%) in the union group and 2 patients (7.1%) in the non-union group developed tibial stress fractures. In the union group, 13.3% of patients underwent at least one secondary procedure compared to 53.6% in the non-union group (p<0.001). FFI (p=0.04) and Coughlin (p=0.03) scores were statistically lower in patients who underwent secondary procedures. Eighty-six patients (84.3%) did not demonstrate fusion between the lateral talus and fibula by CT but PROM scores were not statistically different compared to patients who demonstrated talofibular fusion. CONCLUSION: Tibiotalar arthrodesis utilizing anterior plate fixation is a reliable procedure to achieve ankle fusion based on 50% osseous bridging on post-operative CT scan. However, our results utilizing the accuracy of CT scanning demonstrated a lower rate of ankle fusion than historically reports which are primarily based on plain film imaging. Rates of tibial stress fracture and post-operative wound complications are relatively low with anterior plating, supporting this ankle arthrodesis procedure. Post- operative evaluation of ankle fusions using CT scan should be highly consider regardless of technique.