Poor Correction Capacity of Preexisting Ankle Valgus Deformity after Total Knee Arthroplasty

This study investigated the differences in ankle alignment changes after TKA in patients with varying preexisting ankle deformities. We retrospectively examined 90 knees with osteoarthritis and varus deformity in 78 patients who underwent TKA. Preoperative and postoperative radiographic parameters were analyzed. According to their preexisting ankle deformity, patients were assigned to the valgus or varus group. Overall, 14 (15.6%) cases were of preoperative valgus ankle deformity; the remainder were of preoperative varus ankle deformity. Hip-knee-ankle angle (HKA), tibial plafond-ground angle (PGA), and talus-ground angle (TGA) all exhibited significant correction in both groups; however, tibial plafond-talus angle (PTA) and superior space of ankle joint (SS) only changed in the varus group. The median PTA and SS significantly decreased from 1.2 degrees to 0.3 degrees (p < 0.001) and increased from 2.5 to 2.6 mm (p = 0.013), respectively. Notably, increment PTA positively correlated with increment HKA in the varus group (r = 0.247, p = 0.032) but not in the valgus group. Between-group differences in postoperative PTA (p < 0.001) and increment PTA (p < 0.001) were significant. The degree of ankle alignment correction after TKA differed between patients with preexisting varus and valgus ankle deformities. TKA could not effectively correct the preexisting ankle valgus malalignment.

Automated summary

This study investigated the differences in ankle alignment changes after total knee arthroplasty (TKA) in patients with preexisting varus and valgus ankle deformities. Results showed that TKA corrected ankle alignment differently in patients with varus and valgus deformities, with significant changes in PTA and SS only observed in the varus group. Additionally, the increment in PTA positively correlated with the increment in HKA in the varus group, highlighting the unique responses to TKA in patients with different preexisting ankle deformities.