Physical Activity and Its Relationship to Physical Performance in Patients with End Stage Knee Osteoarthritis

Study Design: Cross-sectional observational design.

Objectives: To compare physical activity levels in men and women with end-stage knee osteoarthritis to those of a comparison group and to examine the relationship between physical activity level and physical performance.

Background: Osteoarthritis of the knee is associated with significant losses in functional performance and high social costs. Although reductions in physical activity are reported, they have not been quantified or explored.

Methods And Measures: Fifty-nine candidates awaiting total knee arthroplasty (TKAC group) and 79 individuals without osteoarthritis (comparison group) participated. Physical activity was assessed using the Voorrips Questionnaire. Performance measures included fast self-paced walk test, timed up-and-go test, and a timed stair performance measure. A subset of subjects completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and underwent muscular strength and endurance testing. The effects of gender and group were tested using GLM ANOVA. Pearson product moment correlations were used to examine relationships between the variables.

Results: All aspects of physical activity were lower (P<.001) in the TKAC group, with a moderate difference in household score (18%) and a large difference in leisure activities (63%). Unlike the comparison group, modest but significant correlations (r = 0.31-0.33, P<.03) were observed between overall physical activity and performance test scores for the TKAC group. Physical activity was not significantly related to pain reported on the WOMAC or during the performance tasks.

Conclusions: The belief that pain limits the physical activity of patients with severe osteoarthritis requires further investigation. The profound differences between a comparison group and patients with end-stage osteoarthritis in physical activity have critical implications for the well-being and effective treatment of this population.