To determine survivorship and establish the ideal correction angle in high tibial osteotomy for primary osteoarthritis through retrospective study.

One hundred and eleven valgus osteotomies of the tibia were performed in seventy-nine patients from 1985 to 1997. The average follow-up period was 9 year 6 months (range, 2.4 to 14.1 years). Failure I was defined as the need for conversion of a high tibial osteotomy to a total knee arthroplasty, and Failure II as the need for conversion or in a patient with less than 60 HSS knee score points. The probability of survival was estimated using the Kaplan-Meier survivorship method.

The HSS knee score averaged 60 points preoperatively, 94 points at the 1 year follow-up and 87 points at the last followup. The 4 year and 14 year survival rates were 99% and 85.0% using the first definition of failure, and 96.4% and 75.1% using the second.

High tibial osteotomy is a reliable method for treating unicompartmental osteoarthrtis, provided that the postoperative femorotibial angle is corrected by more than 7° of valgus.