Plateau-patella Angle: an Option for Assessing Patellar Height on Proximal Tibia Osteotomy

OBJECTIVE To compare the plateau-patella angle method to the methods already established for patellar height measurement in patients undergoing high tibial osteotomy. METHODS This is a retrospective study of 13 patients undergoing medial opening tibial osteotomy. The patellar height was measured in pre and post-operative radiographs by the methods from Insall-Salvati, Caton-Deschamps, Blackburne-Peel and patella-plateau angle, as well as the tibial slope and length of the patellar tendon. Measurements were performed by two knee surgeons at two different times. RESULTS The mean age was 41.33 ± 01.09 years old. The average rates of Caton-Deschamps, Blackburne-Peel, Insall-Salvati and plateau-patella angle were, respectively, 1.00; 0.89; 1.10; and 23.15° preoperatively, and 0.89; 0.78; 1.11; and 20.46°, postoperatively. The correlation of Caton-Deschamps, Blackburne-Pell, and Insall-Salvati indexes and plateau-patellar angle interobserver was 0.72 (p <0.001), 0:54 (p <0.001), 0.65 (p <0.001), and 0.67 (w <0.001), respectively. CONCLUSION The plateau-patella angle method undergoes changes that are correlated with changes in tibial slope after osteotomy, unlike the classical methods. This fact may lead to overestimate the reduction of patellar height after osteotomy. Level of evidence IV. Case Series.