Outcomes of Total Ankle Arthroplasty in Moderate and Severe Valgus Deformity

Abstract

Category: Ankle Arthritis Introduction/Purpose: Among patients with end-stage ankle arthritis, total ankle arthroplasty (TAA) utilization has significantly increased in recent years, while ankle arthrodesis utilization has declined. Significant coronal plane deformity is frequently encountered in this patient population, and was previously considered a contraindication to TAA. However, the advent of newer fixed-bearing prostheses, coupled with improved surgical techniques and a better understanding of ligamentous balancing, have allowed surgeons to extend their indications for TAA with respect to deformity correction. Several authors have demonstrated good outcomes from TAA in patients with significant varus deformities, but not specifically in patients with valgus deformities. We aimed to determine the clinical, radiographic, and patient-reported outcomes of patients with moderate to severe valgus deformity who underwent TAA for end-stage ankle arthritis. Methods: Eighty patients with valgus deformities =10 degrees who underwent TAA were retrospectively reviewed. All surgeries were performed by one of three fellowship-trained orthopaedic foot and ankle surgeons with extensive experience in TAA. One of three prostheses were used: INBONE (Wright Medical Technology, Arlington, TN), Salto-Talaris (Integra, Plainsboro, NJ), or the Scandinavian Total Ankle Replacement (STAR; Stryker, Kalamazoo, MI). We assessed the coronal tibiotalar angle on standardized weightbearing radiographs preoperatively, at one year, and at final follow-up. The visual analog scale (VAS) for pain, Short Form (SF)-36 scale, American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot-ankle scale, and Short Musculoskeletal Function Assessment (SMFA) scores were assessed preoperatively and at final follow-up. Subgroup analyses were performed to determine differences in outcome scores, deformity correction, and maintenance of alignment between patients with moderate (=10 degrees, <20 degrees) and severe (>20 degrees) preoperative deformity. Complication, reoperation, and revision rates were collected from chart review. Results: Mean preoperative valgus deformity was 15.5 ± 5.0 degrees, and was corrected to a mean 1.2 ± 2.6 degrees of valgus postoperatively (Figure; P<.001). An associated flatfoot deformity was present in 33% of patients, 65% of whom required concomitant procedures to address associated deformity. The VAS, SF-36, AOFAS, and SMFA scores improved significantly postoperatively (P<.001 for all), with no difference in amount of improvement between the moderate and severe deformity groups. Deformity correction was maintained at a mean 3.5 (range 2.0-5.9) years of follow-up, with no significant change in the mean tibiotalar angle between one year and final follow-up in either the moderate or severe deformity groups (P=.134 and P=.155, respectively). Reoperation and revision rates did not differ between the moderate and severe deformity groups. Conclusion: Correction of coronal alignment was achieved and maintained following TAA in patients with both moderate and severe preoperative valgus malalignment. Patients demonstrated significant improvement in patient-reported outcome scores regardless of amount of preoperative deformity. Additional procedures may be necessary at the time of TAA to balance the ankle and correct associated deformity in the foot.