Effects of Intensity of Electroacupuncture on Chronic Pain in Patients With Knee Osteoarthritis

A Randomized Controlled Trial

Zheng-tao Lv; Lin-lin Shen; Bing Zhu; Zhao-qing Zhang; Chao-yang Ma; Guo-fu Huang; Jing Yin, Ling-ling Yu; Si-yi Yu; Ming-qiao Ding; Jing Li; Xiao-cui Yuan; Wei He; Xiang-hong Jing; Man Li

Disclosures

Arthritis Res Ther. 2019;21(120) 

In This Article

Background

Acupuncture is an ancient therapeutic technique for pain treatment, which has been proved to have a promising analgesic effect on chronic pain disorders in clinical studies.[1,2] Electroacupuncture (EA), an important form of acupuncture, has been widely used as a substitute for classical acupuncture.[3,4] Knee osteoarthritis (KOA) is a common and disabling condition that typically manifests as attacks of pain around the joints, and it is a typical disease which can develop chronic pain.[5] Both acupuncture and EA have been shown to be effective in the treatment of chronic pain of KOA in randomized controlled trials (RCT).[1,6,7] It has been demonstrated that the intensity of EA is very important for its analgesic effect in animal experiments.[8–10] Moreover, Barlas Panos found that high intensity of EA is more effective in relieving experimental pain in healthy human volunteers than low intensity of EA in RCT.[11] However, the effects of high or low intensity of EA (strong or weak EA) on chronic pain in patients with KOA remain unknown.

The concept of conditioned pain modulation (CPM), previously referred to as diffuse noxious inhibitory controls (DNIC), indicates that under normal conditions, pain can be attenuated by conditioning to a remote body region.[12] The endogenous analgesic system is critical for handling noxious events, and the strength of CPM function can predict the potential of developing chronic pain.[13–15] Quante and colleagues reported that neuronal plasticity of the descending pain inhibitory system impacts CPM function, which is diminished during the development of KOA.[16] Previous study has demonstrated that high intensity of EA (> 2 mA) is similar to a noxious stimulus and may activate CPM function effectively in rats.[10] Thus, we hypothesized that high intensity of EA (strong EA) may be more effective on chronic pain in patients with KOA by strengthening the CPM function. To validate this hypothesis, we undertook this randomized controlled trial to compare the effect of strong EA with weak EA or sham EA on chronic pain in patients with KOA.

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