Osteoarthritis of the knee is a frequent cause of severe disability in the elderly patient. Usually these patients develop a varus or valgus deformity, with narrowing of the joint space due to articular cartilage destruction on the medial or lateral side. Osteotomy of the tibia and fibula performed to shift the weight to the opposite side of the knee joint will usually relieve the patient's symptoms and allow him to walk without pain. A series of 35 patients with osteoarthritis of the knee have been treated by osteotomy with improvement of their symptoms and ability to walk without pain.