Physical activity will not accelerate knee OA joint damage: study

Fears held by people with early knee osteoarthritis that strenuous physical activity may accelerate joint damage have been dispelled by a prospective study.

A ten-year follow up of people with mild knee pain and no radiographic evidence of knee OA found that participation in strenuous activities such as jogging, tennis or skiing had no effect on subsequent risk of radiographic changes of knee OA.

The study, by researchers at Chicago’s Northwestern University Feinberg School of Medicine, also found a suggestion of a protective effect of moderate levels of physical activity (up to two hours a week) against worsening of knee OA.

The findings were derived from a cohort of 1194 individuals aged 45-79 (average 58) and BMI of 26, who were deemed at high risk of developing radiographic knee OA.

When followed up for up to 10 years, 13% of the individuals developed radiographic knee OA. Four distinct trajectories of  physical activity participation were observed: people who had no long term participation in physical activity had a 15.3% incidence of knee OA, whereas those with low  or moderate levels of physical activity had knee OA rates of 10.7% and  9.3%, respectively. People with high levels of strenuous physical activity had a 12.6% rate of knee OA at the 10-year follow up assessment.

The adjusted Odds Ratios for development of knee OA were 0.69 (95%CI, 0.48-1.01) for low-to-moderate level of strenuous physical activities and 0.75 (95% CI 0.53-1.07) for any strenuous physical activities, “suggesting that, even in persons at high risk for knee OA, strenuous physical activity is not associated with development of radiographic changes.”

Engaging in low or moderate levels of physical activity was associated with a reduced likelihood of incident radiographic knee over the 10-year follow-up period, but this was not statistically significant after adjusting for age, BMI and sex.

Being older, having a higher BMI and having more severe knee pain symptoms were associated with being less active.

The study investigators said there was uncertainty and anxiety among people with osteoarthritis about the possible worsening joint damage with physical activity. This was highlighted out by the study showing that nearly 50% of the participants did not engage in any strenuous physical activity and more than 40% had moderate to high frequency of extensive sitting.

These findings confirmed that despite recommendation for exercise in people with OA, sedentary behaviour was an entrenched habit even for those with mild and non-disabling symptoms.

“These observations underscore the need to incorporate physical activity counselling as part of the standard care for high-risk individuals, at an early stage when physical activity engagement is more attainable,” they wrote.

“[The] limited efficacy of current management may in part be attributable to its implementation at a later disease stage, when structural damage already exists and chronic pain sensitization may have occurred. The early stage for the present sample represented an opportunity to proactively intervene for optimal therapeutic outcome.”

The study is published in JAMA Network Open.

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