ObjectiveTo investigate the clinical outcomes and the affecting factors of Judet's quadricepsplasty on the stiffness of post‐traumatic knee flexion.MethodsA retrospective survey was analyzed from June 2015 to October 2018. A total of 15 patients (eight males, seven females; mean age, 48.27 years) with extension contracture of the knee were treated by Judet's quadricepsplasty. All cases were injuries induced by fracture trauma. The mean interval between the initial procedure and quadricepsplasty was 56.2 months (range, 13–276 months). The knee range of motion (ROM) was assessed with a goniometer. The results of the procedure were analyzed by measuring the degrees of flexion of the operated knees at different time points (before, immediately after, and late postoperatively). We evaluated Hospital for Special Surgery (HSS) score, Judet's criteria, change in the degree of knee flexion, and complications.ResultsAll patients were followed up for 14 to 47 months, with an average of 31.53 months. The degree of flexion increased from 23.33° (range, 10°–50°) preoperatively to 107.33° (range, 100°–125°) intraoperatively, followed by a slight fall in the range of flexion in the late postoperative period, which reached an average of 95.33° (range, 60°–115°) in the last follow‐up. The knee joint function was assessed according to the Judet's criteria, eight cases (53.33%) achieved excellent results, six (40%) good, one (6.67%) fair, and zero (0.00%) poor results at final follow‐up. The long‐term excellent and good rate was 93.33%. The range of flexion of the knee during operation and at the last time of follow‐up was better than that before surgery (P < 0.001). The final flexion was significantly lower than that measured at immediate postoperative (P < 0.001). The mean postoperative HSS score for the entire group was 93.73 (range, 89–96). Fifteen excellent results were obtained according to the HSS knee score. Skin infection was seen in one patient (6.67%). There were no complications such as deep sepsis, intraoperative rupture of the quadriceps tendon, fracture of the lateral femoral condyle, skin dehiscence.ConclusionJudet quadricepsplasty is an effective method to treat knee extension contracture and improve knee range of motion (ROM). It should be performed by an experienced orthopaedic surgeon and followed by physiotherapy with continuous passive motion (CPM). The knee ROM obtained with the surgery has an excellent long‐term effect.