Measures of physical performance capture the excess disability associated with hip pain or knee pain in older persons

Background. Hip pain (HP) and knee pain (KP) may specifically affect function and performance; few studies investigate the functional impact of HP or KP in the same population. Methods. Population-based sample of older individuals living in the Chianti area (Tuscany, Italy) (1998-2000); 1006 persons (564 women and 442 men) were included in this analysis; 11.9% reported HP and 22.4% reported KP in the past 4 weeks. Self-reported disability and lower extremity performance, measured by 400-m walk test and by the short physical performance battery (SPPB, including standing balance, chair raising, and 4-m walk test), were compared in participants reporting HP or KP versus those free of these conditions; the relationship of HP or KP with performance and self-reported disability was studied, adjusting for age, sex, hip or knee flexibility, muscle strength, multiple joint pain, major medical conditions, and depression. Results. Participants reporting HP were more likely to report disability in shopping, cutting toenails, carrying a shopping bag, and using public transportation; those with KP reported more disability in cutting toenails and carrying a shopping bag. Participants reporting HP or KP had significantly lower SPPB scores. Adjusting by SPPB, pain no longer predicted self-reported disability, except for "HP-carrying a shopping bag." Conclusions. In our cohort of older persons, those with HP reported disability in a wider range of activities than those with KP. Physical performance measured by SPPB was impaired in both conditions. Reduced lower extremity performance captures the excess disability associated with either HP or KP.