From 1970 to 1987, high tibial osteotomy was performed on 568 knees with osteoarthritis. Among the patients 269 knees in which more than ten years had passed since osteotomy, 53 (62 knees) had died, 3 2 (36 knees) were unable to be followed up because of serious illness, etc, and the whereabouts of 6 were unknown. Thus 56 knees in 4 6 patients could be followed up, 11 knees in 9 men and 45 knees in 37 women. The length of follow-up ranged from 10 to 17 years and 2 months (average, 14.6 years) . The age at the time of surgery ranged from 4 6 to 7 4 (average, 60.2) .
The preoperative femoro-tibial angle (standing) averaged 184.9 ±5.0°, and that five years after osteotomy averaged 172.5±7.2° and at the time of follow-up 173.8±8.0°. The knee score as evaluated by the Japanese Orthopaedic Association Knee scoring system was 5 8 ±12° preoperatively, 88 ± 10° five years after the surgery and 8 2 ± 120 at the follow- up. There was a significant difference (p<0.01) between the preoperative knee score and postoperative one. The average postoperative knee score was higher in the knees in which the femoro-tibial angle was from 170° to 174°. The higher a preoperative radiological grading (standing) was, the worse was the pre and postoperative knee scores. Flexion deformity was reduced postoperatively, but the preoperative maximum f lexion of the knee was not significantly different from the postoperative one.
Thus satisfactory results were obtained more than ten years after high tibial osteotomy with a better alignment of about 10 degrees valgus.
