- The placebo effect, changes due to natural history, and effects of co-therapies are classed as ‘contextual effects’ of treatment, and can cause reductions in pain that are not due to direct physiologic effects.
BACKGROUND & OBJECTIVE
Knee osteoarthritis (OA) is a common and often disabling condition. Acupuncture, ultrasound, laser, and transcutaneous electrical nerve stimulation (TENS) are commonly used treatments for knee OA. This study sought to estimate the extent to which these treatments are effective because of “contextual effects,” which are reductions in pain not attributable to direct physiologic effects, and include the placebo effect, changes due to natural history, and effects of co-therapies.
Potential negative effects associated with the use of passive therapies include reduced self-efficacy and perpetuating confusion in the minds of clinicians and patients about what causes knee pain and how to treat it.
The authors identified 25 RCTs examining treatment of pain in knee OA by acupuncture, ultrasound, laser and TENS. The studies were divided into two groups: treatment by acupuncture (13 studies), and treatment by ultrasound, laser and TENS (12 studies).