OBJECTIVE To investigate the treatment method for collapse separation fractures of lateral tibial condyle. METHODS From January 2003 to October 2008, 45 patients with collapse separation fractures of lateral tibial condyle were treated by surgical method, including 27 males and 18 females,ranging in age from 15 to 76 years,with an average of 37 years. The duration from injury to operation ranged from 1 to 14 days. All of the patients preoperatively underwent X-ray examinations in order to accurately understand the extent of fracture and fracture collapse. All of the 45 fractures with collapse more than 2 mm and widen more than 5 mm were selected for surgical treatment. The lateral surgical approach was used to expose the lateral margin of the lateral meniscus first, and then the reduction of the lateral meniscus and lateral condyle were achieved. The results after operation were evaluated by the Rasmussen criteria, as well as the complications of the knee joint pain, the joint activity, the infection, deep venous thrombosis and recurrent fracture collapse. RESULTS Postoperative X-ray showed anatomical reduction was achieved in 31 patients, 14 patients got nearly anatomical reduction. The plate and screw position were satisfactory. Forty-two patients were followed up,and the duration ranged from 6 to 12 months, with an average of 10 months. Fracture re-displacement,postoperative infection and deep venous thrombosis did not occur after the lifting of external fixation. All the patients had pain disappeared about 10 days after operation,and had no vertical axis percussion tenderness at 3 weeks after operation. The X-ray showed fractures was healed in all patients at 3 months after operation. Joint activity Rasmussen assessment criteria results: 37 patients got an excellent result, 7 good, 1 poor. CONCLUSIONS The incarceration of lateral meniscus and the collapsed bone fragments are two factors which make the reduction of the lateral tibial condyle difficult.