ABSTRACT
Knee osteoarthritis (OA) is no longer seen as a simple “wear and tear” disease in which cartilage thickness decreases on its whole surface through the severity of the disease. Recent research, based on the study of cartilage thickness at some specific areas of the femur, has proved that cartilage could be thicker in OA knees in its non-weight-baring parts. This study uses a new method of 3D cartilage thickness mapping based on CT-arthrography images aiming to confirm what was shown two-dimensionally in the past. The aim was: 1/ to show whether cartilage at the posterior aspect of the medial condyle (PMC) was significantly thicker in OA compared to non-OA knees, 2/ whether cartilage at the posterior part of lateral condyle (PLC) was also thicker in OA knees, and 3/ whether cartilage thickness at this location is correlated to Kellgren and Lawrence grade. After exclusion of secondary causes of OA seen on CTA images, 138 patients were included with different KL grades. OA was defined as KL≥2. Maximal and mean cartilage thickness were significantly thicker in OA (max: 2.45mm [2.34-2.56], mean: 1.59mm [1.51-1.67]) compared to non-OA (max: 2.14mm [2.00-2.26], mean: 1.46mm [1.36-1.55]) knees in the PMC (max: P<0.001, mean: P=0.049) but not in PLC (max: P=0.20, mean: P=0.56). The multiple linear regressions showed that on the medial condyle, maximum cartilage thickness and mean cartilage thickness were associated to age (r=-0.27, P=0.0018, and r=-0.29, P=0.0005 respectively) and KL grade (r=0.39, P<0.0001, and r=0.24, P=0.0049 respectively). The cartilage being thicker in preserved regions could be correlated to a regenerative process, which needs to be confirmed by biochemical and histological studies, and could lead to new therapeutic options.