To compare selected morphological parameters between normal and osteoarthritic (OA) knees, as well as to evaluate differences in these parameters between Kellgren-Lawrence (K-L) grades of OA.
Knee joint morphology was evaluated using magnetic resonance (MR) images of 200 participants with knee OA (50 each of K-L grades 1-4) and 50 without knee OA, matched for age, body mass index, sex, and tibiofemoral angle. Knees with a coronal alignment within five degrees of neutral and no apparent bone loss on radiographs were included. Twenty-one morphologic parameters of the distal femur and proximal tibia were measured on MR images. Correlation between the K-L grade and measured parameters and differences in measured parameters across the K-L grades and between the OA and control groups were evaluated.
The K-L grade was significantly correlated with multiple distal femur measurements including the posterior condylar angle (PCA), lateral epicondyle to posterior condylar cartilage (LEPC) length, medial epicondyle to posterior condylar cartilage (MEPC) length, medial epicondyle to distal cartilage (MEDC) length, medial tibial slope angle, femoral condylar cartilage height difference (FCHDc), and femoral condylar bone height difference (FCHDb) (P < 0.05). A significant difference was identified between the different K-L grades with regard to PCA, LEPC, MEPC, MEDC, and FCHDc (P < 0.05). There was no correlation between K-L grade and measured proximal tibial parameters.
Among knees without significant angular deformity, progression of knee OA is associated with a change in the morphology of the femoral condyles but not of the proximal tibia.