Evaluating the Effect of Electroacupuncture in Knee Osteoarthritis: Protocol for a Multicenter Randomized Controlled Trial [Letter]

Randomized Controlled Trial" by Chen et al, published in Journal of Pain Research. 1 The protocol applies multimodal functional magnetic resonance imaging (fMRI) to explore the mechanisms of electroacupuncture (EA) for knee osteoarthritis (KOA).This fills a notable gap in acupuncture research-the over-reliance on subjective scales and the lack of objective efficacy measures.At the same time, it represents a pioneering effort to clarify the central nervous system mechanisms by which EA relieves chronic pain in KOA.The protocol uses the traditional Chinese acupuncture technique of "shu-ci" (deep needling to the periosteum) to generate a strong stimulus.According to traditional acupuncture theory, this method unblocks meridians and collaterals, regulates Qi and blood, and resolves stasis.The authors also employ multimodal fMRI-including resting-state fMRI, diffusion-weighted imaging (DWI), and MEGA-PRESS magnetic resonance spectroscopy-to assess structural, functional, and neurochemical dimensions, thereby validating and exploring the central neural mechanisms of shu-ci for chronic KOA pain.This innovative approach holds promise for investigating the "skin-brain axis" in KOA. 2 Combining traditional acupuncture theory with advanced neuroimaging reflects a cutting-edge trend in the deep convergence of clinical acupuncture research and neuroscience. 3We are very interested in the study's potential, and we would like to offer a few thoughts on several key aspects of the protocol. Considerations on Deqi Sensation and Electroacupuncture StimulationGuided by the shu-ci theory, the protocol specifies 0.35 mm × 50 mm needles inserted deeply to the periosteum at each acupoint, followed by EA after achieving deqi.The EA parameters are standardized: dense-and-sparse wave, frequency of 2/100 Hz, and intensity of 2 mA for 30 minutes.However, KOA patients are mostly middle-aged or elderly, and their tolerance to electrical stimulation varies.Also, the thickness of periarticular tissue differs between individuals.So it remains unclear whether a fixed current intensity can consistently produce the intended deqi effect or stay within tolerable limits for all participants.We therefore suggest adding quantitative scales to record each patient's tolerance to electrical stimulation and the intensity of deqi.This would help in subsequent dose-response analyses correlating stimulation intensity with brain network responses. Limitations of the Sham Electroacupuncture ControlThe control group receives blunt-tip needle and an unpowered EA device.Participants are told that "the current intensity may be below the threshold of human perception"-a clever design for blinding.But from a neurophysiological perspective, even without skin penetration, the weight of the blunt-tip needle can still stimulate low-threshold