Generic analytical osteotomy model for three-dimensional surgical planning in opening wedge high tibial osteotomy

Opening wedge high tibial osteotomy (OWHTO) is widely used to treat unicompartmental osteoarthritis of the knee caused by degenerative deformations of the anatomical axes of the leg. However, since it is difficult to accurately plan the surgical adjustment degrees such as coronal correction angle and tibial posterior slope angle in order to align the axes before the actual procedure, a number of studies have proposed analytical models to solve this problem. While previous analytical models for OWHTO were limited to specific tibial configurations, this study proposes a Generic analytical osteotomy model (GAOM) and a surgical planning system that are applicable for general tibial morphologies and tibia conditions. The validity and generality of the model were verified in a total of 60 OWHTO cases. Results showed that the tibial shape and the slope of the cut plane significantly affect the adjustment degrees. Comparison between the required degrees and the ones estimated from GAOM resulted in the mean error of 0.12°. The surgical planning system, based on GAOM, allows the operating surgeon to easily calculate surgical parameters needed to treat a patient.