Relationship between range of motion during distal femoral fracture release surgery and postoperative knee joint function: validation of a multivariate prediction model

• Intraoperative range of motion ≥120° during release surgery is a critical threshold for optimal functional recovery, with each additional degree below 120° reducing recovery risk by 3.3%. • Age ≥60 years, lack of continuous passive motion exercise, postoperative complications, low preoperative Hospital for Special Surgery score, and large medial tibial joint line change are independent risk factors for poor recovery. • A multivariate prediction model incorporating six independent risk factors demonstrates excellent discrimination (AUC=0.821), calibration (Brier=0.097), and clinical utility for individualized risk assessment. • The nonlinear dose-response relationship between intraoperative range of motion and recovery risk, identified via restricted cubic spline analysis, highlights the importance of achieving at least 120° intraoperative motion.