Electroacupuncture Significantly Reduces Chronic Pain and Central Sensitization Biomarkers in Knee Osteoarthritis Patients

Knee osteoarthritis (KOA) is a prevalent chronic condition leading to debilitating pain and functional impairment. While conventional treatments focus on symptom management, many patients experience persistent pain, often exacerbated by central sensitization (CS), a phenomenon where the central nervous system becomes hypersensitive to pain signals. This involves neurochemical changes, including elevated levels of neurotransmitters and neuropeptides like glutamate (Glu), glutamine (Gln), substance P (SP), and calcitonin gene-related peptide (CGRP). Current therapies often fail to adequately address CS, highlighting a critical gap for non-pharmacological interventions that can modulate these central mechanisms.

This randomized controlled trial enrolled 90 patients with chronic pain due to KOA, assigning them to either an EA group (n=45) or a sham-EA group (n=45). Both groups received health education. The EA group received electroacupuncture at specific acupoints (e.g., Neixiyan (EX-LE4), Dubi (ST35)) on the affected knee, using a dense-disperse wave at 2 Hz/100 Hz and an electric current of 1 mA to 2 mA. Each session lasted 30 min, once daily, 6 sessions a week for 4 consecutive weeks. The sham-EA group received identical treatment duration and acupoint placement but without electrical stimulation. Primary endpoints included NRS for pain, PPTs for local/distal sensitivity, WOMAC and SF-12 for function/quality of life, CSI for central sensitization, and serum levels of Glu, Gln, SP, and CGRP.

Electroacupuncture demonstrated significant improvements across multiple pain and functional metrics. Compared to baseline, the EA group showed a significant decrease in NRS scores for pain at rest and during activity at week 2, 4, 8, and 16. Functional outcomes also improved, with significant reductions in WOMAC subscales and total scores observed at week 4 and 16. Crucially, EA significantly modulated central sensitization, evidenced by a decrease in CSI scores and serum levels of key biomarkers at week 4. > Specifically, serum levels of glutamate, glutamine, substance P, and calcitonin gene-related peptide (CGRP) were all significantly reduced in the EA group by week 4 (P<0.0, though the full p-value was truncated in the abstract). These reductions in neurochemical markers of central sensitization correlated with the observed clinical pain relief and functional improvements, suggesting a direct mechanistic link between EA and central pain processing. The sham-EA group did not show comparable improvements in these parameters.