[Effect of a valgization osteotomy with external wedge removal on patellar height and femoro-patellar arthritis]

This retrospective study assesses the effect of proximal tibial lateral closing wedge osteotomy on the patellar height and patellofemoral osteoarthritis. This osteotomy was performed on 59 knees (53 patients) for medial gonarthrosis. No cast immobilization was used. The patients presented a mean varus deformity of 9.4 degrees before surgery and a mean valgus angulation of 4.2 degrees at maximum follow-up. The theoretical effect of the osteotomy was evaluated using a geometrical model. The actual effect was evaluated using Caton's index which was measured 3 times (before the osteotomy, after one day and with a mean follow-up of 24.8 months after the osteotomy). The theoretical measure showed an increase in the patellar height. Conversely, in the patients, the measured Caton's index did not significantly increase (0.85 to 0.835) (epsilon = 0.882; risk = 5%) because of shortening of the patellar ligament. Clinical improvement in the patellofemoral compartment was noted. No radiological progression of the arthritis occurred in the patello-femoral compartment. We advocate proximal tibial lateral closing wedge osteotomy to treat femoro-tibial osteoarthritis in patients with femoropatellar osteoarthritis or with patella infera.