Does Preoperative Valgus Deformity Severity Predict Outcomes in Total Ankle Arthroplasty vs Ankle Arthrodesis?

Abstract

Category: Ankle; Ankle Arthritis Introduction/Purpose: Coronal plane deformity is an important consideration in the treatment of ankle arthritis, and valgus alignment presents its own unique challenges. Ankle fusions were previously considered the gold standard, but advancements in total ankle arthroplasty (TAA) implant design and surgical technique have increased its popularity in the treatment of even large coronal plane deformities. Although many studies have compared fusion to arthroplasty, no studies have directly compared these two treatments in the treatment of valgus ankle arthritis. The purpose of this study was to evaluate and compare clinical and radiographic outcomes of TAA to ankle fusion in the treatment of valgus ankle arthritis. Methods: 137 patients with valgus ankle arthritis who underwent either TAA or ankle fusion were identified through a prospectively collected database. Minimum clinic follow-up was two years. Preoperative radiographs were measured for tibiotalar angle to include patients with valgus ankle arthritis five degrees or greater. Axial alignment views were also analyzed for preoperative hindfoot alignment. Patients who underwent tibiotalocalcaneal fusion or had previous ankle corrective osteotomy were excluded. Complications, failures, revisions, and reoperations were recorded. Failures were defined by explant of a metal component. Reoperations included any additional related ankle/hindfoot surgery including subtalar fusion. Patients were categorized by severity of preoperative valgus deformity into 4 groups: 5-10 degrees, 11-15 degrees, 16-20 degrees, and greater than 20 degrees. Outcomes were compared across these groups between TAA and ankle fusion. There were 98 patients who underwent TAA and 39 patients who underwent ankle fusion. Median follow-up was 50.4 months (inner quartile 37.4-74.1). Results: Patients who underwent TAA with greater than 15 degrees of preoperative valgus deformity had higher rates of failures, revisions, and reoperations compared to those who underwent fusion with the same deformity severity. Overall, 44% of patients (60/137) had major or minor complications. There were 6 failures (6%) in the TAA cohort and 5 failures (13%) in the fusion cohort. 36% of fusions (14/39) underwent reoperation which was a higher rate compared to 18% of TAAs (18/98) (p=0.03). Combined fusion and TAR cohorts had less complications, failures/revisions, and reoperation rates as the severity of deformity increased (p<0.01). Conclusion: Severity of preoperative valgus deformity is an important consideration in the surgical treatment of ankle arthritis. Patients with greater than 15 degrees of preoperative valgus had lower rates of failures, revisions, and reoperations when treated with fusion. Patients with less than 15 degrees of preoperative valgus had lower rates of failures, revisions, and reoperations when treated with TAA. Overall, patients with greater preoperative valgus deformity had less complications. Patients with valgus ankle arthritis remain a challenging problem with high complication rates regardless of surgical procedure and additional procedures should be considered to treat any coronal plane instability and foot deformity.