Objective To investigate the clinical efficacy of 3D printing technique combined with osteotomy in the treatment of complex tibial plateau fractures involving the posterolateral condyle.Methods The clinical data of 47 patients with complicated tibial plateau fractures involving the posterolateral condyle who were treated with 3D printing technology and tibial lateral condyle osteotomy from January 2012 to February 2015 were retrospectively analyzed.There were 19 males and 28 females aged from 21 to 69 years (mean 50.3 years).All of them were closed fractures without neurological and vascular injuries.The time between injury and operation was 4 to 19 days (average,6.7 days).All the patients were treated with tibial lateral condyle osteotomy and bilateral plate fixation with anterolateral approach and posteromedial approach.Three-dimensional CT scans were performed preoperatively and 1 ∶ 1 to mimics model was made by 3D printing technique based on the data after conversion.Refer to the 3D fracture model to accurately design the osteotomy line to improve the operation scheme.During the operation,anterior and lateral anterior combined with posterior medial incision were performed,and the tibia external condyle osteotomy was conducted to accurately expose the external posterior condyle fracture block of the tibia platform,and bilateral plate was applied after reduction.The fracture reduction was evaluated according to the Rasmussen score of the knee joint.The knee joint function was evaluated by the score of the hospital for special surgery (HSS).Results All 47 patients were followed up for 13.2 months (range,7-19 months).Immediate postoperative X-ray showed good fracture reduction.The union time of fracture was 14.3 weeks (range,12-18 weeks).The knee joint Rasmussen score one year after operation was 13-18 (average,15.73),including 33 cases excellent,12 cases good and 2 cases fair.The excellent and good rate was 95.7％ (45/47).HSS score was 67 to 94 (average,82.67),among which 31 cases were excellent,13 cases good,2 cases fair,and 1 case poor (postoperative refusal to rehabilitate exercise resulted in joint stiffness).The excellent and good rate of 89.9％ (44/47).Knee joint activity was-5°-0°-135°,with the average range of 125.5°.No common peroneal nerve injury,important vascular injury,postoperative infection,internal fixation failure and other serious complications was found.Conclusion 3D printing technology can help to accurately display the specific situation of the posterior tibial condyle fractures,which is conducive to the surgeon to develop a more intuitive plan of reduction.The method of tibial lateral condyle osteotomy can clearly reveal the tibial plateau posterolateral condylar fractures.With accurate osteotomy the surgical field can be fully exposed,and ultimately achieve a satisfactory result.Therefore,3D printing combined with tibial lateral condyle osteotomy is an effective method for complex tibial plateau fractures involving the posterolateral condyle.