Abstract
OBJECTIVES: Sarcopenia is prevalent in middle to old age. We aimed to investigate the association between muscle strength and the incident knee osteoarthritis (OA). METHODS: 12,043 participants were collected from the China Health and Retirement Longitudinal Study. The effects of sarcopenic obesity (defined by obesity in combination with possible sarcopenia) on knee OA onset were calculated using Poisson regression models. Mediation analysis was fit to estimate mediating proportion of muscle strength on the association between obesity and incident knee OA. RESULTS: The study all enrolled 12,043 participants with 2,008 progressed to knee OA. Poisson analyses demonstrated causal association of general obesity (RR:1.23, 95% CI: 1.08 to 1.39) and abdominal obesity (RR:1.23, 95% CI: 1.11 to 1.35) with knee OA onset. For the risk of incident knee OA, participants with the highest level of normalized grip strength had a decreased risk of incident knee OA by 0.33 (RR:0.67, 95% CI: 0.60 to 0.75) times compared to the control group, and chair-rising time was associated with increased risk of incident knee OA by 0.65 (RR:1.65, 95% CI: 1.17 to 2.33) times. Sensitivity analysis identified similar results. Participants with sarcopenic obesity were about 2 times risk of incident knee OA than reference group. Normalized grip strength and chair-rising time mediated the association between obesity and incidence of knee OA. CONCLUSIONS: Sarcopenic obesity is correlated with an increased risk of knee OA. Muscle strength recovery may alleviate the risk of incident knee OA in middle to old age with obesity.