Acupuncture Enhances Signals at Sensitized Acupoints to Elevate Pressure Pain Threshold in Knee Osteoarthritis Patients

Objective: To observe the pressure pain threshold (PPT), skin conductance (SC) and blood perfusion (BP) of the sensitized acupoints in patients with knee osteoarthritis (KOA), and explore the mechanism of acupuncture at the sensitized acupoints for treating diseases. Methods: Eleven healthy subjects and 11 unilateral KOA patients were recruited from July 2020 to March 2021 in this study. The PPT, SC and BP of control acupoints in healthy controls, and non-sensitized and sensitized acupoints in KOA patients were measured and compared between baseline and after manual acupuncture (MA) treatment. Results: Before MA treatment, lower PPT was observed at the sensitized acupoints compared with non-sensitized and control acupoints (P<0.05). After MA treatment, PPT at the sensitized acupoints increased significantly in KOA patients (P<0.05). Before MA treatment, there was no statistical difference in SC and BP among control, non-sensitized and sensitized acupoints (P>0.05). Compared with the control and non-sensitized acupoints, there were significant increases of SC and BP in sensitized acupoints of KOA patients after MA treatment (P<0.05 or P<0.01). Conclusion: MA at sensitized acupoints could elevate PPT of KOA patients, which may be associated with the increment of SC and BP.