It is well-known that the femorotibial angle of 165° to 170° is desirable to get good results from HTO. In this study, we followed up 46 joints of 36 cases (average age, 62 years) for 8 to 112 months (average, 43 months), and FTA was 165°-175° in 40 joints at the follow-up investigation. Results were scored by the knee-rating scale of the Japan Knee Joint society. Excellent results (over 80 point) were obtained in 21 knees, good (70-79) in 6, and poor in 13 (under 69 points).
Then 29 joints of this group were analyzed with arthroscopic evaluation of lateral compartments. 16 joints with normal cartilage had 88.6 point on an average, 6 joints with deep cartilage erosion 71.6, 3 joints with cartilage erosion down to subchondral bone were 69.3 and 4 joints of subchondral bone exposed were 67.2.
Arthroscopic evaluation of lateral compartment is useful to decide indication of HTO.
