Valgus Drift after Total Ankle Arthroplasty

CATEGORY: Ankle; Ankle Arthritis INTRODUCTION/PURPOSE: Total ankle arthroplasty (TAA) is a common treatment for ankle arthritis, but many challenges exist when attempting to correct and balance coronal plane deformity. Varus ankle arthritis tends to be stiffer and often leads to a more stable TAA, but valgus ankle arthritis tends to have more laxity especially in the setting of a progressive collapsing foot deformity. Failure to achieve appropriate deformity correction and soft tissue balance can result in recurrence of the deformity with valgus drift. The purpose of this study was to evaluate the longitudinal coronal plane alignment as well as outcomes in patients treated with TAA with resultant valgus drift. METHODS: 98 patients who underwent TAA for valgus ankle arthritis were identified through a prospectively collected database. All patients had a minimum of 2 year follow-up. The tibiotalar angle was measured on preoperative radiographs to include patients with valgus ankle arthritis five degrees or greater. Radiographic alignment in the postoperative period was compared to the alignment at final follow-up. Complications, failures, revisions, and reoperations were recorded. Patients were categorized by severity of preoperative valgus deformity into 3 groups: 5-10 degrees, 11-20 degrees, and greater than 20 degrees. Valgus drift was defined as greater than 5 degrees of valgus shift at final follow-up when compared to the postoperative alignment. Median follow- up was 49.2 (37.2-68.3 inner quartile) months. RESULTS: Patients with greater than 20 degrees of preoperative valgus deformity had an initial postoperative alignment of 2 degrees of valgus and ended with an average of 5.5 degrees of valgus at final follow-up. The groups of patients with 5-10 degrees as well as 11-20 degrees of valgus were corrected to neutral (0 degrees) in the initial post-op period and ended with a final postoperative valgus alignment of 2.5 degrees and 2 degrees, respectively. Overall, 16 patients (18%) had greater than 5 degrees of valgus drift after their surgery, of which 2 failed and were revised (13%) and 5 had reoperations (31%). CONCLUSION: All groups of preoperative valgus deformity severity had some valgus shift overall at final follow-up. The most severe preoperative valgus deformities were least likely to be corrected to neutral with the index procedure and also on average drifted back to over 5 degrees of valgus. Patients with valgus drift after TAA can still have a good result but should be monitored closely. Overall, they did not have a high failure rate. This study emphasizes the necessity of correcting both the ankle and foot deformity when performing TAA for valgus ankle arthritis in order to maintain deformity correction.