Medial and lateral gonarthrosis treated with high tibial osteotomy. A prospective study.

A prospective series comprising 52 knees in 48 patients suffering from medial or lateral unicompartmental gonarthrosis and treated by means of high tibial osteotomy shows, by comparing mechanical axis (MA) 0 degrees corrected knees, how important is the overcorrection of the MA into valgus in medial osteoarthritis. The clinical results were significantly correlated to overcorrection, the results 2 years postoperatively being better than those obtained at a follow-up 1 year after the operation. Of the results, 82% were good within a limit of +/- 3 degrees after 2 years, while only 77% were correspondingly good 1 year postoperatively. In lateral gonarthrosis overcorrection was not as good, but there was a mean overcorrection of +2 degrees, and with respect to this overcorrection, the results were quite acceptable. The results were directly correlated to the opening up of the joint space affected (80%) and diminution or disappearance of subluxation, 1/3 being 0 degrees preoperatively, 1/2 postoperatively in medial gonarthrosis. In lateral gonarthrosis, subluxation was increased, with 2/3 being 0 degrees preoperatively, 1/3 being 0 degrees postoperatively. The extension deficit in varus knees significantly diminished after valgus osteotomy; the change in valgus knees was also evident but not significant. The mean value of extension deficit was below 5 degrees in all cases at the 2 years' follow-up examination. However, 95% of all patients showed good or fair results after a follow-up period of 2 years.