Assessment of Tibial Slope Angle and Patellar Height after Medial-opening Tibial Osteotomy

OBJECTIVE To measure the variation in posterior tibial slope angle and patellar height in patients who underwent proximal tibial valgus-producing osteotomy using the medial-opening wedge technique. METHODS Anteroposterior panoramic radiographs of the lower limbs and lateral radiographs of the knee obtained before and after tibial valgus-producing osteotomy on 46 patients with unicompartmental arthrosis of the knee were analyzed. RESULTS In 23 patients, an external fixator was used to gradually apply a medial-opening wedge; and in the other 23, a blocked plate with a stop bar was applied as a fixation method. Patients with tricompartmental knee disease and those who underwent osteotomy to treat fracture sequelae were excluded from this study. After surgery, the mean increase in the tibial slope was 1.7 degrees (p < 0.01) in the group in which the blocked plate with a stop bar was used; and 2.7 degrees (p < 0.05) in the group in which the external fixator was used. There was no statistical difference between the groups regarding the increase in the posterior tibial slope. CONCLUSION The patellar height did not present any change in the cases in which the plate was used, when measured using the Insall-Salvati method, but it presented a decrease in 11 cases (47.8%) when the Caton-Deschamps method was applied. The same tendency was observed regarding change in the patellar height in the cases in which the external fixator was used, such that a decrease was observed in eight cases (34.7%) only when measured using the Caton-Deschamps method.