medwireNews: Contrary to the belief of some patients, exercise does not harm the knee joints in those at risk for or with knee osteoarthritis (OA), according to a meta-analysis of randomized controlled trials.
In fact, Alessio Bricca (University of Southern Denmark, Odense) and colleagues say their analysis indicated that molecular biomarkers associated with inflammation and cartilage breakdown or turnover were reduced with exercise, leading them to speculate that “if anything, exercise therapy is beneficial for cartilage.”
The analysis included 12 studies that looked at the influence of strengthening and/or aerobic exercise in 1114 participants. All of the studies took biomarker samples at 1–6 months, and looked at molecular biomarkers relating to inflammation, grouped into markers of inflammation and cytokine receptors, and biomarkers relating to cartilage turnover, grouped into proteases, collagen turnover, glycoproteins, and glycosaminoglycans.
Together the studies performed 57 comparisons, of which 63% found that biomarker concentrations were similar between the exercise and control groups, while 30% reported a decrease in concentrations with exercise and 7% reported an increase—all in favor of exercise therapy.
Previous meta-analyses have similarly found that exercise is not associated with excess risk for people with knee OA, note the researchers, and magnetic resonance imaging trials have shown that exercise does not harm cartilage.
They add that the findings of the current study are “in line with these previous findings and support exercise therapy being a safe treatment for knee joint cartilage in people at risk of, or with established, knee OA.”
Molecular biomarkers obtained from the synovial fluid appeared to be more sensitive to changes with exercise therapy than samples from urine or blood because of the proximity of the synovial fluid to the joint tissues, say Bricca and colleagues, and they recommend that future studies should use synovial fluid for assessment. And, as no single biomarker has yet been shown to explain the development and progression of OA, they also suggest that future studies focus on a set of biomarkers, rather than a single marker.
Limitations of the analysis included a lack of studies reporting findings for the same biomarkers, substantial heterogeneity among the included studies, and wide confidence intervals, leading the researchers to rate the quality of the evidence as low.
Even so, they conclude in Arthritis Care & Research that the clinical implication of their findings “is that people at risk of, or with established, knee OA can be told that exercise therapy is not harmful, and if anything, is positive for the turnover of articular cartilage and inflammation.”
By Catherine Booth
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