Abstract
BACKGROUND: Prior studies of the relationship of physical activity to osteoarthritis (OA) of the knee have shown mixed results. The objective of this study was to determine if differences in the progression of knee OA in middle- to older-aged runners exist when compared with healthy nonrunners over nearly 2 decades of serial radiographic observation. METHODS: Forty-five long-distance runners and 53 controls with a mean age of 58 (range 50-72) years in 1984 were studied through 2002 with serial knee radiographs. Radiographic scores were two-reader averages for Total Knee Score (TKS) by modified Kellgren & Lawrence methods. TKS progression and the number of knees with severe OA were compared between runners and controls. Multivariate regression analyses were performed to assess the relationship between runner versus control status and radiographic outcomes using age, gender, BMI, education, and initial radiographic and disability scores among covariates. RESULTS: Most subjects showed little initial radiographic OA (6.7% of runners and 0 controls); however, by the end of the study runners did not have more prevalent OA (20 vs 32%, p =0.25) nor more cases of severe OA (2.2% vs 9.4%, p=0.21) than did controls. Regression models found higher initial BMI, initial radiographic damage, and greater time from initial radiograph to be associated with worse radiographic OA at the final assessment; no significant associations were seen with gender, education, previous knee injury, or mean exercise time. CONCLUSIONS: Long-distance running among healthy older individuals was not associated with accelerated radiographic OA. These data raise the possibility that severe OA may not be more common among runners.