Majority of osteoarthritic knee (OA knee) shows varus deformity which causes to the wear of medial joint cartilage and the complaint of knee pain. High tibial osteotomy (HTO) is often performed; wedge osteotomy above tibial tubercle provides the shift toward the lateral articulation of mechanical axis passing through medial articulation preoperatively, regeneration of medial joint cartilage and improvement of the knee complaints. Indication of HTO is as follows; (1) knee pain, (2) less than 500 m of continuous walking distance, (3) lateral thrust of the knee at walking, (4) narrowing (less than 3mm) of medial joint space in knee A-P radiograph at standing, (5) more than 180 degrees of standing femoro-tibial angle. This is thought to be almost equal to less than 60 points of JOA OA knee assessment score. Long term follow-up results have been reported to be good and satisfactory.