To investigate the links between knee pain characteristics and restricted mobility outside the home, and how these are influenced by mobility-specific activity limitation, age, sex, socioeconomic status, environmental factors, and comorbidity.
We conducted a cross-sectional survey of community-dwelling adults age > or = 50 years. A total of 2,252 responders reporting pain in and around the knee in the last year were eligible. The primary outcome was self-reported restricted mobility outside the home in the previous 4 weeks (dichotomized as present or absent).
Knee pain severity was strongly associated with restricted mobility outside the home, an association largely mediated by perceived limitation in walking. After adjusting for demographic and socioeconomic characteristics, individual contributions from selected comorbidities, knee pain severity, limitation in walking, and specific environmental factors remained. These environmental factors included perceived need of aids and assistance (adjusted odds ratio [OR] 3.1, 95% confidence interval [95% CI] 2.2-4.4), poor access to public transportation (adjusted OR 2.3, 95% CI 1.4-3.9), and having no access to a car (adjusted OR 1.6, 95% CI 1.1-2.4).
There are a range of potential health and social targets that, if addressed, might reduce restricted mobility outside the home in middle-aged and older individuals with knee pain. Our results suggest that, in addition to treating the knee symptoms, such targets might include comorbidity, walking ability, and environmental barriers such as poor access to public transportation. Moreover, removing environmental barriers may reduce immobility outside the home even in the continued presence of osteoarthritis symptoms and specific activity limitations.