Navigation-Assisted One-Stage Total Knee Arthroplasty With Extra-Articular Corrective Osteotomy for Knee Osteoarthritis With Femoral and Tibial Extra-Articular Deformity: A Case Report.

Background: Knee osteoarthritis (OA) with extra-articular deformity (EAD) is a rare condition for which achieving accurate alignment with total knee arthroplasty (TKA) is difficult. Extra-articular corrective osteotomy may be necessary for severe deformities. Case Presentation: A 76-year-old man underwent TKA for knee OA with EAD due to malunion after fractures of the femur and tibia. The femoral varus and the tibial valgus/recurvatum deformities were mild and corrected by intra-articular osteotomy using navigation (i.e., navigation-assisted standard TKA). However, the femoral antecurvatum deformity was severe, and we performed extra-articular corrective osteotomy simultaneously with TKA. Navigation was used not only for TKA but also for extra-articular corrective osteotomies. The osteotomy site was fixed with a cemented stem and metaphyseal sleeve. The postoperative hip-knee-ankle angle was 1° varus, the femoral implant was implanted at 0.5° varus/0.5° flexion, and the tibial implant was implanted at 0.5° varus/0° posterior slope. Two years after surgery, improvements were obtained in the range of motion from 15°-95° to 0°-110°, the Knee Society Score from 39 to 92 points, and the functional score from 35 to 100 points. Conclusions: One-stage TKA with extra-articular corrective osteotomy achieved good clinical results due to accurate alignment using navigation and firm fixation of the osteotomy site using cemented-stem and metaphyseal sleeve without any fixation devices.