Background: The normal values for axial alignment and joint line obliquity of the knee that indicate a successful valgus upper tibial osteotomy have not been established and reported in the literature.
Methods: To identify those parameters we prospectively followed 51 patients with 54 lateral closing wedge upper tibial osteotomies performed after preoperative and postoperative analysis of standardized hip-to-ankle radiographs with a software computer program (OASIS).
Results: Of the 54 knees, 18 (33.3%) underwent additional surgery. The average follow-up of the remaining 36 knees was 10 years (range 6.9-13.8 years). The cumulative osteotomy survival rate was 89% at 5 years and 76% at 10 years. Compared with patients whose postoperative femorotibial angle was 174 degrees -180 degrees , the patients whose postoperative femorotibial angle was <174 degrees or >180 degrees did worse with respect to osteotomy failure. Ten knees were at a decreased risk of failure. These knees had a postoperative femorotibial angle of 174 degrees -180 degrees , lateral joint line obliquity of <4 degrees , and a medial plateau force distribution of 40%-60%. The knees that met these criteria had 100% survival at 5 and 10 years, whereas the rest of the knees had survival rates of 86% and 70%, respectively.
Conclusions: We believe that using these criteria during preoperative planning may improve the survival of upper tibial osteotomy provided a precise, reproducible surgical technique and rigid fixation can be performed.