Physicochemical and mechanical evaluation of acupuncture needles

Acupuncture is a traditional Chinese medicine technique that involves the insertion of filiform needles into the body. Currently, various brands of acupuncture needles are available for purchase and product quality control is intended to ensure the safety of both the patient and the acupuncturist.

The purpose of this study was to assess the quality of acupuncture needles using physical-chemical and mechanical tests according to International Organization for Standardization (ISO) standard 17218:2014.

We evaluated nine different brands of 0.25 mm × 30 mm acupuncture needles. The needles were characterized using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) techniques for morphological and compositional evaluation at 300× magnification. Mechanical tests were used to determine puncture performance, intensity and needle tip sharpness according to ISO 17218:2014 using an Instron 4411 with controlled needle displacement. Puncture force was measured in Newtons, and a stereomicroscope was used to evaluate structural changes after the intensity test.

SEM-EDS analyses indicated deformations, scratches and imperfections in various brands of needle, particularly Açomed and Complementar. Following the intensity test, all brands exhibited deformations at the needle tips. The Uniqmed brand had the lowest puncture performance test force (median = 0.033 N, 95% confidence interval (CI) = 0.030-0.035 N), while Açomed had the highest (0.117 N, 95% CI = 0.109-0.132 N). The Dragon brand had the lowest sharpness test force (0.026 N, 95% CI = 0.025-0.029 N), while Complementar had the highest (0.060 N, 95% CI = 0.056-0.064 N).

Despite statistically significant disparities, no group exceeded the limits set by ISO 17218:2014. Although there are a few research studies on this topic, some authors have opted not to reveal brand names, which makes direct comparisons problematic. As a result, we anticipate that the findings from this study may be used in future meta-analyses and ISO 17218:2014 revisions.