Evidence from two traditional systematic reviews and one systematic umbrella review suggested that in patients with knee osteoarthritis, physical activity significantly reduced pain and improved function, performance, and health-related quality of life compared with usual care (not consistently defined), no treatment, or sham interventions.
Limited evidence from one systematic review suggested higher temporary increases in minor pain with exercise than with sham interventions, and no difference in worsening pain, falls, or death between exercise and control groups. Also, limited evidence from a systematic review included in the systematic umbrella review indicated that three to 30 weeks of low-impact activity combining muscle-strengthening, stretching, and aerobic elements were not associated with serious adverse events in older adults, and the number of total knee replacement surgeries was not significantly different between patients who underwent physical activity compared to no-activity control groups over a two month to 24-month observation period.
Sources of uncertainty included the fact that the systematic reviews were based on studies of unclear or low methodological quality. Also, all three included systematic reviews reported significant heterogeneity of their included studies, lacked a standardized definition of "usual care", and had no information on symptom duration, clinical characteristics, comorbid conditions, and concomitant treatments. Therefore, it was difficult to determine if the findings were due entirely to the investigated interventions and controls or if other factors influenced the results.
There was no study identified that examined the comparative clinical effectiveness of physical activity versus pharmacological interventions in individuals with knee osteoarthritis.