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.