Vigorous exercise may hasten knee OA progression

Vigorous, but not moderate, physical exercise was associated with a significantly greater risk of knee osteoarthritis progression over one year in a longitudinal analysis of 99 patients.

Engaging in vigorous activity was associated with a 1.38 times increased risk of progression, defined as an increase in either cartilage or meniscus defect scores at one year.

The odds ratios were not significantly increased for moderate activity but were close to significance for walking activity, said at the World Congress on Osteoarthritis.

The analyses adjusted for age, body mass index, sex, pain, and modified Whole Organ Magnetic Resonance Scores for cartilage and meniscus in the first block, and International Physical Activity Questionnaire.

“We did not see that moderate activity was associated with progression, and this indicates that we need to further investigate the optimal dosage of physical activity for someone with knee osteoarthritis,” said radiology department, University of California, San Francisco.

Although greater physical activity has been shown to reduce pain and improve function, the results support more recent work suggesting that certain types of activity may be associated with disease progression. Walking 10,000 steps or more per day was found to increase the risk of meniscus and cartilage lesions on MRI in people with knee OA, while high and very low levels of self reported activity were associated with greater cartilage relaxation times on 2T MRI at four years in data from the Osteoarthritis Initiative.

For the current analysis, 99 participants in the ongoing, longitudinal Cartilage Loading and Unloading (CLOC) knee OA study underwent 3T MRI of the knee using a sagittal, high-resolution 3D fast spin-echo Cube sequence at baseline, which was repeated one year later. Defects were graded by experienced radiologists. Participants with OA had a baseline radiographic KL score of more than one and were symptomatic: controls had a KL of zero or one no knee symptoms.

By one year, 35 participants showed progression (14 with OA and 21 controls) and 64 did not. Surprisingly lateral compartment and, more expectedly, in the patella in 12 persons, said at the meeting sponsored by the Osteoarthritis Research Society International.

No significant baseline differences existed between nonprogressors and progressors with respect to age (53.2 years vs 50.8 years), body mass index (24.4kg/m² vs. 24.5kg/m²), and sex (62.5 percent male vs.48.5 percent female).

Knee injury and Osteoarthritis Outcome Score subscale scores were also similar to pain (85.7 vs. 82.4) and symptoms (84.5 vs. 83.4).

Progressors had engaged, however, in significantly more metabolic equivalent-minutes per week of vigorous exercise than did nonprogressors. Metabolic equivalent-minutes per week were similar for moderate activity and walking.YOUR DOSE OF MEDICINE   Charles C. Chante, MD