Associations Between Obesity With Low Muscle Mass and Physical Function in Patients With End-Stage Knee Osteoarthritis

OBJECTIVE: To investigate the prevalence of obesity with low muscle mass and its impact on physical function, quality of life (QOL) and pain in patients with end-stage knee osteoarthritis over 65 years old. METHODS: In this cross-sectional study, we assessed a total of 562 patients. After separating the group into males and females, we divided patients into 4 further groups: normal BMI with normal muscle mass, obesity with normal muscle mass, normal BMI with low muscle mass and obesity with low muscle mass. All patients completed stair climbing test (SCT), 6-minute walk test, timed up and go test (TUG), instrumental gait analysis, Western Ontario McMaster Universities Osteoarthritis Index, VAS, and EuroQOL 5 dimensions questionnaire. RESULTS: Obesity with low muscle mass was diagnosed in 6 males subjects (7.8%) and 9 female subjects (1.9%). Patients with obesity and low muscle mass performed the SCT-ascent and descent significantly slower than other body composition groups in both males and females. TUG in males and gait speed in females were also significantly slower in the obesity with low muscle mass group. Stepwise multiple linear regression analysis revealed that in males, obesity with low muscle mass was significantly predictive of SCT ascent (β = 0.409, p < 0.001), SCT-descent (β = 0.405, p < 0.001), and TUG (β = 0.283, p = 0.009), and in females, obesity with low muscle mass was significantly predictive of SCT-ascent (β = 0.231, p < 0.001), SCT-descent (β = 0.183, p < 0.001), and gait speed (β=-0.129, p = 0.004). CONCLUSIONS: This study confirms that the combination of obesity and low muscle mass is associated with impaired physical function in patients with end-stage knee osteoarthritis.