Moderate physical activity may prevent cartilage loss in women with knee osteoarthritis: data from the Osteoarthritis Initiative

OBJECTIVE: To examine the impact of physical activity (PA) on cartilage thickness loss in knee osteoarthritis (KOA).

METHODS: 689 participants with radiographic KOA (Kellgren/Lawrence grade ≥2) at baseline, from the Osteoarthritis Initiative completed the Physical Activity Scale for the Elderly (PASE) questionnaires at annual intervals over four years. Magnetic resonance imaging-based cartilage thickness change in the medial femorotibial compartment (MFTC) over four years was the main outcome. The impact of PASE tertiles (low, moderate, high) on changes in MFTC cartilage thickness was estimated using a mixed effect model adjusted for baseline characteristics. Furthermore, straficiation by sex was performed for secondary analyses.

RESULTS: Structural progression of MFTC cartilage loss of -0.20 mm (95% confidence interval: -0.22 to -0.17mm) was observed in the entire cohort, with no statistically significant difference between PA levels after adjustment for baseline characteristics. A sex-by-physical activity interaction was observed in the adjusted analysis (p=0.02). Stratification by sex showed that women with low PA had a statistically greater cartilage loss than women with moderate PA level (adjusted between group difference -0.09 mm [-0.16 to -0.02 mm]), whereas no significant differences were observed in men.

CONCLUSION: While physical activity was not associated with cartilage thickness loss in the whole cohort, this relationship significantly differed between sexes. In women, but not in men, moderate PA may slow down structural disease progression compared to low PA levels. For both men and women, high PA does not appear to be more detrimental than lower PA levels for cartilage thickness loss. This article is protected by copyright. All rights reserved.