Evidence from a systematic review suggests that moxibustion is more effective than conventional drug therapy for osteoarthritis of the knee, as well as in rheumatic conditions in general, and also that it improves benefits when added to conventional drugs. Several systematic reviews of acupuncture for osteoarthritis of peripheral joints/knee and hip/knee alone have concluded that it is statistically superior to sham acupuncture and to usual physician care, and similar in benefit to some other active interventions such as exercise regimes. 

There have been many randomised controlled trials of acupuncture and/or moxibustion for osteoarthritis: only those too recent for the systematic reviews are discussed separately here. All seven studies (six for knee and one for hip) reported significantly better changes in the acupuncture than the control groups; in two, this superiority was only manifest in the longer- rather than shorter-term. Most reported outcomes for pain and function, some for overall benefit, and one for gait patterns in particular. The acupuncture was more commonly electro- than manual, and moxibustion was added in two trials. The controls used were either sham acupuncture (four studies) or Western drugs (three). These recent trials thus strengthen the findings of the reviews.

In general, acupuncture is believed to stimulate the nervous system and cause the release of neurochemical messenger molecules. The resulting biochemical changes influence the body's homeostatic mechanisms, thus promoting physical and emotional well-being. Stimulation of certain acupuncture points has been shown to affect areas of the brain that are known to reduce sensitivity to pain and stress.

Acupuncture treatment may help to relieve pain and improve function in patients with osteoarthritis by:
stimulating nerves located in muscles and other tissues
inhibiting pain through the modulatory effects of endogenous opioids
regulating metabolism-related genes and pathways
inhibiting the activity of cytokines that are mediators of inflammation
reducing inflammation, by promoting release of vascular and immunomodulatory factors
increasing local microcirculation (Komori 2009), which aids dispersal of swelling.