An undertreated group has emerged in modern orthopaedic surgery--patients with degenerative disease of the medial compartment of the knee who are young and active, who may have undergone multiple arthroscopic procedures, and who have been advised to "take it easy and wait for a total knee replacement." If the knee is in varus, unilateral frame distraction with upper tibial corticotomy is advocated to achieve valgus alignment. The procedure is straightforward, with few complications in our first 100 cases, with almost universal success. Even if it is believed that all tibial osteotomies will eventually fail and require a total knee replacement, this method, by which bone stock is actually enhanced, length is maintained, and the ligamentous structures about the knee are undamaged, is superior to methods previously described.