92 patients scheduled for high tibial osteotomy (HTO) were randomized to either a closing wedge or an openinig wedge HTO. The purpose of this study was to compare long-term clinical outcome measures and radiographic outcome between groups. Over a 10-year period, patients were assessed for hip-knee-ankle angle, pain, function, and conversion to total knee arthroplasty (TKA). At 10 years, 32% of the closing-wedge group and 22% of the opening-wedge group had undergone TKA; this difference was not statistically significant. Additionally, there were no significant differences in hip-knee-ankle angle, pain, or function between the two groups at 10-year follow-up.