The medial compartment and patellofemoral joint degenerate more severely in early stage knee osteoarthritis: a cross-sectional study.

The purpose of this study was to compare the differences of degenerative characteristics of medial, lateral regions, femoral, patellar, and tibia parts of the knee joint in the early stage of knee osteoarthritis (OA).A total of 66 patients with early-stage knee OA and 22 healthy volunteers who have no knee-related clinical symptoms were enrolled in this cross-sectional study. T2 mapping and 3D dual-echo images were acquired with a 3.0T MR scanner. The degenerative changes of the articular cartilage were quantified by a T2 mapping and cartilage thicknesses analysis. Any structural changes were conducted using the Whole Organ Magnetic Resonance Imaging Score (WORMS).In patients with knee OA, the thicknesses of medial cartilages were significantly thinner than lateral ones (2.13 mm vs. 2.34 mm, p<0.0001), but with higher T2 values (40.38 ms vs. 38.4 ms, p<0.0001) and WORMS scores (12.12 vs. 0.47, p=0.004). No significant differences were observed between medial and lateral cartilage in the healthy volunteers. The T2 values of the femoral (p<0.001) and patellar (p=0.012) cartilages of OA patients were higher than that of the healthy controls. Within OA group, the T2 values of femoral (p<0.0001) and patellar (p<0.0001) cartilages were higher than tibial ones. Moreover, the WORMS scores of femoral (p=0.001) and patellar (p<0.0001) cartilages were higher than that of the tibial ones.This study demonstrates that the medial compartment and patellofemoral knee joint degenerate more severely in patients with early-stage knee OA.