The coronal alignment differs between two‐dimensional weight‐bearing and three‐dimensional nonweight bearing planning in total knee arthroplasty

Abstract Purpose The goal of this study is (1) to assess differences between two‐dimensional (2D) weight‐bearing (WB) and three‐dimensional (3D) nonweight‐bearing (NWB) planning in total knee arthroplasty (TKA) and (2) to identify factors that influence intermodal differences. Methods Retrospective single‐centre analysis of patients planned for a TKA with patient‐specific instruments (PSI). Preoperative WB long‐leg radiographs and NWB computed tomography were analysed and following radiographic parameters included: hip–knee–ankle angle (HKA) (+varus/−valgus), joint line convergence angle (JLCA), femorotibial subluxation and bony defect classified according to Anderson. Preoperative range of motion was also considered as possible covariate. Demographic factors included age, sex, and body mass index. Results A total of 352 knees of 323 patients (66% females) with a mean age of 66 ± 9.7 years were analysed. The HKA differed significantly between 2D and 3D planning modalities; varus knees (n = 231): 9.9° ± 5.1° vs. 6.7° ± 4°, p