An analysis of age-related loss of skeletal muscle mass and its significance on osteoarthritis in a Korean population

This study was conducted in order to analyze the effects of sarcopenia on age-related osteoarthritis (OA) of the knee in a Korean population. All the Korean subjects who visited the Yeungnam University Medical Center Health Promotion Center between 2008 and 2012 in order to undergo a routine medical examination were enrolled. A total of 5,723 young, healthy people (2,959 males, 2,764 females) enrolled as normal subjects and 23,473 subjects (13,006 males and 10,467 females) were included for evaluation of the effects of sarcopenia on OA. There were 266 subjects who followed-up bioelectrical impedance analysis at a 4-year interval. Of 327 subjects enrolled in this study, knees with anteroposterior X-rays were assessed according to the Kellgren-Lawrence (K/L) grade. Skeletal muscle mass index (SMI) and basal metabolic rate (BMR) showed a steady decrease with the advance of age (p < 0.01), but SMI showed strong positive correlation with BMR (r = 0.72, β = 30.96, p < 0.01). During the 4-year interval, BMR showed a significant decrease with aging (p < 0.01), consistently with the decrease of SMI. Knees with normal SMI were prone to be designated as K/L grade 0 or 1; however, subjects with sarcopenia showed a trend toward the higher K/L grade, classified as knee radiological osteoarthritis (ROA) (p < 0.01). The results of this study may indicate that sarcopenia as age-related loss of skeletal muscle mass is interactively correlated with the presence and severity of age-related OA.