To evaluate the clinical and radiological results of an opening wedge osteotomy for an osteoarthritic knee, and compared these results with those of a closing wedge osteotomy.

The study included 27 patients (29 cases) with an opening wedge osteotomy (Group A) and 30 patients (30 cases) with a closing wedge osteotomy (Group B). The radiological results obtained regarding the degree of osteoarthritis, femur-tibia angle, tibial alignment, posterior tibial slope and patellar height using the Insall-Salvati's method were analyzed. HSS score was used for evaluation of the clinical results.

Preoperatively, there were no significant differences between the two groups regarding the degree of osteoarthritis, the femur-tibia angle, tibial alignment, posterior tibial slope, and patellar height. Two years after surgery, the femur-tibia angle and tibial alignment were significantly improved to 7.7° valgus and 1.3° valgus, respectively, and the patellar height was not changed significantly in group A. Similar degrees results were obtained in group B. The tibial posterior slope increased from 3° to 10.7° in group A and decreased from 4° to 3.7° in group B. Clinically, the HSS score was improved from 74 points preoperatively to 93 points 2 years postoperatively in the opening group, and was similar to the improvement observed in the closing group. The complications included 1 delayed union in the opening group, and 3 cases of superficial peroneal nerve palsy and 1 delayed union in the closing group.

An opening wedge osteotomy is a relatively simple and safe procedure that gives similar radiological and clinical outcomes to a closing wedge osteotomy, without peroneal nerve palsy. However, surgeons should take care in preventing an increase in the tibial posterior slope.