RESUMO
INTRODUCTION: Kinematically aligned total knee arthroplasty (KA-TKA) has gained interest for achieving more favorable clinical outcomes than mechanically aligned TKA. One of the advantages of KA-TKA is reported to be an easy acquisition of intraoperative soft-tissue balance without excessive medial release for varus osteoarthritis. However, we hypothesized that the prosthesis type affects intraoperative soft-tissue balance even in the KA-TKA. The present study aimed to compare intraoperative soft-tissue balance and clinical outcomes of KA-TKAs using single-radius (SR) or multiradius (MR) prostheses. MATERIALS: AND METHODS: Consecutive 70 cruciate-retaining modified KA-TKAs (31 SR and 39 MR) were performed in patients with varus-type osteoarthritis using a navigation system. Intraoperative soft-tissue balance including joint component gap and varus/valgus balance was measured with femoral component placement and patellofemoral joint reduction throughout the range of motion using offset-type tensor and compared between the two groups. Two years postoperatively, the range of motion and 2011 Knee Society Scores were compared between the two groups. RESULTS AND CONCLUSION: Joint component gaps showed no significant differences between the two groups from 0 to 30 degrees of flexion. However, during 60 to 120 degrees of flexion, joint component gaps of SR group showed significantly larger values than those of MR group (p < 0.05). There were no significant differences in varus/valgus balance throughout the range of motion between the two groups. The postoperative clinical outcomes showed no significant differences between the two groups. INTERPRETATION: Despite no difference in clinical outcomes, joint component gap showed different patterns due to the prosthesis type in modified KA-TKAs.