Body composition and knee cartilage properties in healthy, community-based adults

BACKGROUND: Although obesity is widely accepted as a risk factor for knee osteoarthritis, whether weight per se or the specific components of body composition are the major determinants of properties of articular knee cartilage is unclear. OBJECTIVE: To examine associations between anthropometric and body composition measures and knee cartilage properties in healthy adults. METHODS: 297 healthy adults with no clinical knee osteoarthritis were recruited from an existing community-based cohort. Anthropometric measures and body composition, including fat-free mass and fat mass assessed using bioelectrical impedance analysis, were measured at baseline (1990-4) and current follow-up (2003-4). Tibial cartilage volume and tibiofemoral cartilage defects were assessed using MRI at follow-up. RESULTS: After adjustment for potential confounders, baseline and current fat-free mass, independent of fat mass, were positively associated with tibial cartilage volume (all p<0.001). Increased fat-free mass over the time period was positively associated with tibial cartilage volume (p<0.001). Current fat mass was negatively associated with tibial cartilage volume (p = 0.004). Baseline and current fat mass were weakly associated with increased tibiofemoral cartilage defects (p = 0.06 and p = 0.07, respectively), independent of fat-free mass. CONCLUSION: The findings suggest a beneficial effect of fat-free mass, but a deleterious effect of fat mass, on knee cartilage properties in healthy adults. This suggests that weight-loss programmes aimed at reducing fat mass but maintaining muscle mass may be important in preventing the onset and/or progression of knee osteoarthritis.