Knee osteoarthritis compromises early mobility function: The Women's Health and Aging Study II

Objective. To examine associations between osteoarthritis (OA) of the knee and early functional limitations in a cohort of high-functioning older women, and evaluate the contributions of muscle strength, body weight, and pain severity to these limitations. Methods. Cross sectional analyses were conducted on baseline data of the Women's Health and Aging Study II (WHAS II), an observational study of disability transitions in a cohort of women aged 70-79 upon entry and who were representative of the one-third highest-functioning community-resident women. Standardized questionnaires and examinations were used to assess knee OA features, medication use, pain severity, knee extensor muscle strength, and body weight. Functional limitation was assessed using validated performance measures and self-report measures of task modification and task difficulty. Results. Sixty-nine women classified as "symptomatic" for knee OA, 48 with "asymptomatic/intermittently symptomatic," knee OA, and 285 with "no knee OA" were included in the final analysis. Despite selection for their high level of self-reported function, performance was slower and task modification was more frequently reported among women with knee OA than women without knee OA. Lower knee extensor strength, higher body weight, and greater pain severity were associated with knee OA, and also with functional limitations. Conclusion. Knee OA appeared to be associated with early functional limitations in this cohort of high-functioning, older, community-resident women. Lower knee extensor strength, higher body weight, and pain severity were closely associated with these limitations. The extent to which modification of these factors attenuates knee OA associated functional decline should be investigated.