RESUMO
OBJECTIVES: A non-penetrating sham needle has been considered as a reliable control treatment in the field of acupuncture research. However, some concerns with regard to the credibility of sham needles have also been raised. We investigated whether there were differences in biomechanical properties and acupuncture sensation ratings in the process of needling between verum acupuncture (VA) and sham acupuncture (SA). METHODS: To quantify biomechanical force during needling in a cross-over design, we used a computer-controlled needling system. Fourteen participants received VA or SA at acupuncture point LI4, with no visual impact. They were asked to complete an acupuncture sensation form, including penetration, acute pain and DeQi sensations, and to identify the needling type they received. RESULTS: We found that there was a significant difference in insertion force between VA and SA (68.5 ± 12.2 vs. 27.2 ± 3.9 gf; p < 0.001). Participants clearly distinguished between the two kinds of stimulation and rated higher sensory ratings in the VA session (penetration sensation: 4.9 ± 3.1 vs. 1.7 ± 2.3, acute pain: 4.9 ± 2.7 vs. 1.9 ± 2.6, respectively; p < 0.01). CONCLUSIONS: Our findings demonstrate that differential biomechanical forces such as insertion and pullout force contribute to the sensation of real and non-penetrating sham needles.
