Sarcopenia progresses with aging, but the effect of muscle loss on degenerative joint disorders has not been precisely evaluated. We assessed the distribution of lean body mass (LBM) in middle aged women who had osteoarthritis (OA) of the knee for < 5 years.
Two hundred thirty-five Japanese women aged 45-69 years, including 117 with knee OA for < 5 years, and 118 age and sex matched healthy controls were studied. Body composition measurements were carried out by segmental bioelectrical impedance using 8 surface electrodes. Anthropometric data consisting of LBM of upper extremities/body weight (U-LBM/W), LBM of trunk/body weight (T-LBM/W), and LBM of lower extremities/body weight (L-LBM/W) for knee OA participants were compared to corresponding data for controls. In the knee OA group, the significance of correlations between anthropometric data and Lequesne index of severity for knee OA and between anthropometric data and disease duration were assessed.
L-LBM/W was significantly lower in knee OA participants compared with controls (19.2 +/- 2.7% vs 21.0 +/- 2.9%; p < 0.0001). However, no significant differences in U-LBM/W and T-LBM/W were observed between the knee OA and control groups (p > 0.2). L-LBM/W did not correlate significantly with the index of severity or disease duration (p > 0.2).
Decline in L-LBM/W, but not U-LBM/W or T-LBM/W, may be important in the pathogenesis of knee OA.