Approximately 10–20% of people 60 years or older experience pain in their knees. Although rheumatologists know exercise is an effective treatment for osteoarthritis (OA), studies suggest the effects vary by patient. Perhaps the best-documented benefits of exercise for OA patients are improvements in pain and functional outcomes.
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A new meta-analysis reviewed the efficacy of exercise therapy for pain, function, performance and quality of life. The systematic review found exercise may confer a moderate reduction in pain, and improve function and performance, in individuals with knee and hip OA. Additionally, the improvement in quality of life, although smaller than the effect on other outcomes, was significant.
Siew-Li Goh, MD, a graduate student at the University of Nottingham, U.K., and colleagues compared patients who exercised with those who received standard care, such as physician follow-up, physical activity or those who are on a waiting list for which the active intervention would be offered only after the study period. They confirmed previous reports that found improvements from exercise increase gradually and peak at two months. After two months, the effects of exercise slowly diminished until 9–18 months. Between nine and 18 months, exercise was no better than standard care. This time-dependent effect was similar for all outcomes. The review was published May 21 in the Annals of Physical and Rehabilitation Medicine.1
The meta-analysis included 77 randomized, controlled trials examining all types of exercise and multiple outcomes. In the trials, the outcome most frequently reported was objective performance, followed by pain, function and quality of life. The patient age and sex distributions were similar across all outcome measures. The authors note the conclusions from the meta-analysis were limited, because all of the studies were observational. Additionally, many of the clinical trials included in the review were of poor quality, with neither physicians nor patients blinded to the exercise interventions. Moreover, half of the trials with performance outcomes had inadequate assessors blinding.
The authors found patients who were younger than 60 years old with knee OA and those not waiting for joint replacement were more likely to benefit from exercise therapy. Additionally, improvement was generally better for patients recruited from specialist or hospital centers than those recruited from general practice, community or mixed settings. The authors also acknowledged the potential determinants of age, joint and recruitment for specialist/hospital settings should be confirmed with individual patient data.
In general, the results support the idea that exercise produces greater improvement in patients with milder, as opposed to more severe, OA. The authors were surprised to find functional improvement was significantly better in studies without explicit exercise adherence measurements. However, they suggest caution in interpreting this finding, because it may reflect the ease or feasibility of reporting and monitoring exercise in those studies.