Injuries to the ligament and other supporting structures of the knee joint are becoming very frequent because of the increasing popularity of sports and the complexity of traffic & industrial accidents in the modern society. There have been much development in undtrstanding the anatomy, function and biomechanics of the knee in recent years. Accurate surgical technique, energetic physiotherapy and appropriate use of brace are essential to obtain the maximum rehabilitation of the injured knees. It is long realized that some sort of knee brace is necessary as a means of stabilizing the injured knee either as a conservative treatment or as a adjuvant treatment treatment pre-or postoperatively before full rehabilitation is attained. We have introuced Lenox Hill Derotation Brace for the first time in Korea, employed in 24 case(26 knees) and found the following advantages. 1. It is light and easy to apply. 2. It is possible to control all kind of the knee instability. 3. It is possible to engage in any activity with the Brace in place without limitation of the knee motion. therefore, we recommend the Brace as a very usefull adjuvant for the proper treatment of the injured knee.