Women have an increased risk of knee osteoarthritis (OA). However, little is known about gender differences in cartilage health before the onset of clinical knee OA. The aim of this study was to examine whether there are longitudinal gender differences in knee cartilage in a cohort of healthy, asymptomatic adults with no clinical knee disease.
Two hundred seventy-one participants (169 women) aged between 50 and 79 years with no clinical history of knee pain or pathology were examined using magnetic resonance imaging at baseline and 2.3 years later. From these images, changes in tibial and patella cartilage volume and progression of cartilage defects were determined.
In multivariate analyses, after adjustment for potential confounders, the average annual percentage loss of total tibial cartilage volume was significantly greater in women (1.6% [95% CI, 1.1-2.2]) than in men (0.4%[95% CI, -0.4 to 1.2]) (P = 0.05 for difference). Likewise, the female gender was also associated with an increased risk for the progression of tibiofemoral cartilage defects (odds ratio, 3.0; 95% CI, 1.1-8.1; P = 0.03). At the patella,the average annual percentage loss of cartilage volume was significantly greater in women (2.3% [95% CI, 1.7-2.8]) than in men (0.8% [95% CI, 0.1-1.6]) (P = 0.02 for difference).
The female predisposition toward knee OA may, at least in part, be due to gender differences in cartilage health, even before the onset of clinical knee disease. Understanding the mechanism for these gender differences may provide a means to reduce the risk of knee OA in women.