Objective To discuss the effectiveness of operation technique for antero-medial rotatory instability (AMRI) of the knee joint caused by motorcycle. Methods Between June 2007 and December 2009, 32 cases of AMRI caused by motorcycle were treated. There were 28 males and 4 females with an average age of 35.5 years (range, 20-50 years). The interval between injury and surgery was 5-10 days (mean, 7 days). The anterior cruciate ligament (ACL) was injured at the attachment point of the condyles crest; the medial collateral ligament (MCL) was injured at central site in 19 cases, at medial condyles of femur in 10 cases, and at medial condyles of tibia in 3 cases, which were all closed injuries. The bone avulsion of condyles crest was fixed by steel wire and MCL was repaired. Results Red swelling and a little effusion occurred at the incision in 1 case, and the other incisions healed by first intention. Traumatic arthritis of the knee occured in 5 cases. Thirty-two cases were followed up 16-22 months (mean, 18.5 months). The X-ray examination showed that the fracture union time was 5-8 weeks (mean, 6 weeks) after operation. At last follow-up, the extension of knee joint was 0° and the flexion of the knee joint was 110-170° (mean, 155°). According to the synthetic evaluating standard of International Knee Documentation Committee, 24 cases were rated as A level, 6 cases as B, 1 case as C, and 1 case as D at last follow-up. Lysholm knee score was 85.93 ± 3.76 at last follow-up, which was significantly higher (t=53.785, P=0.000) than preoperative score 37.54 ± 3.43. Conclusion In patients with AMRI caused by motorcycle, steel wire is used to fix the bone avulsion of condyles crest and MCL should be repaired simultaneously as far as possible. And associating with the early postoperative functional exercise, the short-term effectiveness is satisfactory, but long-term effectiveness still need further follow-up observation.