Effect of Electroacupuncture (EA) and Manual Acupuncture (MA) on Markers of Inflammation in Knee Osteoarthritis

Knee osteoarthritis is one of the leading causes of disability in older adults, characterized by pain, stiffness, and functional limitation. Although traditionally viewed as a "degenerative" disease, growing evidence shows that inflammation plays a central role in the development and progression of osteoarthritis. Pro-inflammatory cytokines such as TNF-α and IL-1β promote cartilage destruction, while anti-inflammatory cytokines such as IL-13 may have protective effects. Acupuncture, including its electroacupuncture and manual acupuncture variations, has been studied as a nonpharmacologic alternative for the treatment of osteoarthritis, but its mechanisms of action remain poorly understood, especially with respect to anti-inflammatory effects.

This controlled clinical trial specifically investigated how electroacupuncture and manual acupuncture affect inflammatory markers in patients with knee osteoarthritis. The study randomized 58 participants aged 45–75 years with mild to moderate osteoarthritis to receive electroacupuncture or manual acupuncture for 8 weeks. The protocol included 24 sessions of 30 minutes each, using local points such as ST-34, ST-35, ST-36 and distal points. In the electroacupuncture group, 2/100 Hz electrical stimulation was applied at an intensity of 0.2 mA.

Blood samples were collected before and after treatment for analysis of inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-8, IL-18, IL-4, IL-10, IL-13, IL-15, IL-17), chemokines (MCP-1, CCL5), and cartilage degradation biomarkers (MMP-1, MMP-3, MMP-13, COMP). The results showed that both treatments significantly reduced important pro-inflammatory cytokines: TNF-α decreased by 42% in the electroacupuncture group and 12% in the manual acupuncture group, while IL-1β was reduced in both groups. The cartilage degradation biomarkers MMP-3 and MMP-13 also decreased significantly in both groups. At the same time, there was an increase in the anti-inflammatory cytokine IL-13.

Clinically, both treatments produced clinically significant improvements: pain (VAS scale) was reduced by 26.8 points in the electroacupuncture group and 25.4 points in the manual acupuncture group, exceeding the minimum clinically important difference threshold. Joint function (WOMAC scale) improved by 9.5 points in the electroacupuncture group and 8.3 points in the manual acupuncture group. Although electroacupuncture showed a significantly greater reduction in TNF-α compared with manual acupuncture, no statistically significant differences were observed between groups for other markers or clinical outcomes. Adverse events were minimal and self-limited, consisting mainly of mild pain at the needle site and small hematomas.

This study provides important evidence that the clinical benefits of acupuncture in knee osteoarthritis are partially mediated by specific anti-inflammatory effects. The reduction of pro-inflammatory cytokines TNF-α and IL-1β, together with the decrease in cartilage degradation markers, suggests that acupuncture may not only relieve symptoms but also influence underlying pathologic processes. Limitations include the relatively small sample size, absence of a placebo/control group, assessment of systemic markers only (not local synovial fluid), and follow-up limited to 8 weeks, which did not allow evaluation of long-term effects on structural progression of osteoarthritis.