Abstract
We evaluated the results in 37 patients (57 knees) who had had a high tibial osteotomy for either gonarthrosis or osteonecrosis. The operations were performed between 1974 and 1980. The mean length of follow-up was 6.4 years in a range of 5 to 10.5 years. In a majority of the cases, surgery consisted of a oblique osteotomy. Clinical evaluation was done using the OA knee joint function scoring system recently established in the Japanese Research Association for Knee Joint, which we estimated was a severer evaluation system than the three universities trial plan.
At 1 to 3 years after osteotomy, 91.2% of the cases showed satisfactory results, with evaluation scores of knee joint function of 70 points or above. However, at 5 years or more only 70.2% showed such scores. The main cause of the deteriorating, results was shown to be recurrent medial arthrosis resulting from undercorrection. The most significant factor in clinical results after high tibial osteotomy was considered to be the alignment obtained by osteotomy. We recommend an osteotomy in which the mechanical axis would pass through a point 20 to 50% lateral to the midpoint of the knee. In addition, we consider that an excess overcorrection in which the mechanical axis would pass through a point up to 100% lateral to the midpoint, would be more acceptable than a slight undercorrection.
