後天性大腿骨後屈変形を伴う、インプラント保持下のロボット支援下人工膝関節全置換術：症例報告

We describe a 58-year-old male with severe posttraumatic osteoarthritis and distal femoral recurvatum deformity following adolescent fracture fixation. Preoperative imaging demonstrated a healed malunion stabilized by a lateral locking plate and tricompartmental osteoarthritis with 12° recurvatum. A single-stage robotic-assisted kinematically aligned total knee arthroplasty was performed using cementless cruciate-retaining components while retaining the femoral plate. Careful preoperative planning and intraoperative adjustment of bone resections enabled restoration of joint line orientation, balanced soft tissues, and stable press-fit fixation without stems or osteotomy. At two-year follow-up, the patient reported excellent function and pain-free mobility, with outcome scores including KOOS JR 91.98, Oxford Knee Score 47, and Forgotten Joint Score 100. This case highlights the feasibility of robotic-assisted, hardware-retaining, cementless TKA in the setting of complex extra-articular deformity, avoiding staged hardware removal or constrained implants while achieving durable clinical outcomes.