92 patients with osteoarthritis (OA) of the medial compartment of the knee were randomized to receive closing-wedge high tibial osteotomy and a plaster cylinder cast or opening-wedge osteotomy fixed with a Puddu plate. After 1 year, there was a statistically significant difference between the two groups in the mean post-operative hip-knee-ankle angle, in which the mean of the closing wedge group was closer to the goal of an overcorrection of valgus of 4 degrees. In addition, a smaller proportion of patients in the closing-wedge group required surgery to remove the staples compared to the proportion of patients in the opening-wedge group who required removal of the Puddu plate. Both groups demonstrated improvement in pain, knee function, and walking distance; however, the two groups did not differ significantly.