In 1,262 participants of the Netherlands Epidemiology of Obesity Study, a population-based cohort (age 45-65 years, 53% women, and median body mass index [BMI] 27 kg/m(2) ), knee OA was defined following modified American College of Rheumatology criteria. BMI and fat-free mass (as proxy for muscle mass) were assessed by bioelectrical impedance analysis, and comorbidities by self-report. HRQOL was assessed using the Short Form 36 physical component summary (PCS) score