Assessment of the deformation model of the proximal tibia in the course of degenerative disease: analysis of the 3-dimensional mathematical model

BACKGROUND: The high tibial osteotomy (HTO) is an effective knee-saving procedure, which relieves arthritis symptoms and prolongs the life of the knee joint. This procedure requires detailed preoperative planning. Usually, the contralateral side is used as a template for this purpose. Some intra-operative complications made us thinking how exactly the degenerative disease alter the epiphysis if the tibia. Our study aimed to assess morphological differences between healthy knees and degenerative knees using a three-dimensional mathematical model. METHODS: Twenty-three computed tomography (CT) examinations were collected out of 237 individuals screened for inclusion/exclusion. The inclusion criteria were: age between 40 and 69 years, degenerative knees with visible varus deformation, and signs of radiological osteoarthritis (OA) in the knee joint (such as joint space narrowing, subchondral sclerosis, subchondral cyst formation, and osteophytes. The average age of the included patients was 56.2 years. Nine men’s and 14 women’s knee joints were used for the calculation and comparisons. RESULTS: Female varus knees showed much more significant variability in tibial plateau dimensions according to sides of the body than male ones. These differences were statistically significant (P=0.03). In comparison between the basal bone and bones with OA, variability in 3D dimensions was statistically significant only for lateral condyles in males’ right knees (P=0.025). Compared to the degenerative knees to the most average, healthy knees, there were significant differences in the measured surface area of males’ right knees for both condyles: for the medial P=0.0046, for lateral P=0.005. Male varus knees had a statistically more considerable (P=0.028) surface area for all measured condyles. Angles of inclination differ significantly between knees with OA and healthy knees in the male population for the medial condyle plateau in the left knees. The female population for the lateral condyle in left knees and the medial condyle in right knees. CONCLUSIONS: The proximal tibial plateau deformation showed high variability in the two-dimensional and three-dimensional analysis in the designed mathematical models. This finding must be considered during preoperative planning.