Objective: Increased BMI is a well-recognized risk factor for radiographic knee osteoarthritis (rKOA); however, the contributions of the components of body composition, body fat distribution, and height to this association are not clear.
Research methods and procedures: We examined 779 women > or = 45 years of age from the Johnston County Osteoarthritis Project. Body composition was assessed using DXA, and rKOA was defined as Kellgren-Lawrence grade > or = 2. Logistic regression models examined the association between rKOA and the fourth compared with the first quartiles of anthropometric, body composition, and fat distribution measures adjusting for age, ethnicity, and prior knee injury.
Results: The adjusted odds ratios and 95% confidence interval of BMI and weight were 5.27 (3.05, 9.13) and 5.28 (3.05, 9.16), respectively. In separate models, higher odds of rKOA were also found for fat mass [4.54 (2.68, 7.69)], percent fat mass [3.84 (2.26, 6.54)], lean mass [3.94 (2.22, 6.97)], and waist circumference [4.15 (2.45, 7.02)]. Waist-to-hip ratio was not associated with rKOA [1.45 (0.86, 2.43)], and percent lean mass was associated with lower odds [0.20 (0.11, 0.35)]. Taller women had higher odds of rKOA after adjustment for BMI [1.77 (1.05, 3.00)].
Discussion: This study confirms that BMI and weight are strongly associated with rKOA in women and suggests that precise measurements of body composition and measures of fat distribution may offer no advantage over the more simple measures of BMI or weight in assessment of risk of rKOA.