Design of dry-needling and acupuncture sham devices: an illustrative review

Abstract

Dry needling and acupuncture are non-pharmacological therapies for managing musculoskeletal pain. Although they noticeably differ in their application and proposed rationale, the common ground between the two therapies is the invasive soft-tissue needling. Over the past 30 years, researchers have developed and used various forms of sham/placebo needling devices in randomized controlled clinical trials for assessing a causation-based relationship between needling into myofascial trigger points (dry needling) or acupoints (acupuncture) and purported therapeutic outcomes. However, no clear guidelines exist for choosing a sham needling device for research purposes. Based on the English literature search on PubMed, EMBASE, J-STAGE, and Taiwan Electronic Periodicals, the present illustrative review identified five forms of sham dry-needling/acupuncture needle devices that had been validated and/or used in clinical trials. As of today, however, there is a lack of standardization in sham needling devices, making it difficult to compare results across different studies.

INTRODUCTION

When investigating the potential efficacy of medical treatment in clinical trials, the researchers need to consider spontaneous recovery, patients’ expectations (placebo effects), and random chance unrelated to the treatment effects. These confounders can be optimally controlled by having patients randomly allocated into real (active) and placebo (inactive) treatment groups and masking them to the groups; thus, they would not know whether or not they received the real treatment^{1, 2)}. In dry needling and acupuncture-related trials of the past 30 years, different forms of placebo or sham needling devices have been designed to help determine the efficacy of true treatments. The present paper examined sham dry needling/acupuncture devices that had been validated and published in peer-reviewed indexed journals.

METHODS

Four electronic databases, PubMed (National Institutes of Health, Bethesda, MD, USA), EMBASE (Elsevier, Amsterdam, Netherlands), J-STAGE (Japan Science and Technology Agency, Tokyo, Japan) and Taiwan Electronic Periodicals (Airiti, New Taipei City, Taiwan), were searched for relevant English literature published from the launch of each database until February 2025. The search terms used were dry needling, acupuncture, sham, placebo, validation and validity. The inclusion and exclusion procedure involved selecting and reviewing the resultant literature to determine if it was an original article, a clinical trial, or a validity study that employed a sham or placebo needling device for human participants. However, if the appearance of true and sham needling devices used in a given study was not morphologically identical, which is crucial for effective blinding, that study was excluded.

RESULTS

Based on the above database search, 10 articles^{3,4,5,6,7,8,9,10,11,12)} had been selected in which five forms of sham dry needling/acupuncture needling devices were identified. All the devices’ blinding effectiveness was validated and four of them were already used in clinical trials. All the sham needling devices were based on a non-penetrating nature and believably had minimal physiological effects (Table 1).

Table 1. Comparison of five sham needling devices.

Device	Masking	Blinding tactics	Validity confirmed	Used in trial yet
Streitberger3, 4) (Fig. 1)	Single-blind	Patients can observe the insertion of a stainless steel needle and experience a sensation similar to skin penetration (Fig. 1).	Yes3)	Yes4)
Park5, 6) (Fig. 2)	Single-blind	Patients can observe the insertion of a stainless steel needle and experience a sensation similar to skin penetration (Fig. 2).	Yes5)	Yes6)
Takakura7, 8) (Fig. 3)	Double-blind	Patients can observe a needle insertion and have a penetration-like sensation. Clinicians’ fingers can experience a feeling similar to that of a needle moving within the patient’s skin during the needle insertion/withdrawal (Fig. 3).	Yes7)	Yes8)
Dry needle9,10,11) (Fig. 4)	Single-blind	Patients can observe the insertion of a stainless steel needle and experience a sensation similar to skin penetration (Fig. 4).	Yes9, 10)	Yes11)
Ryodoraku12) (Fig. 5)	Single-blind	Patients can observe the insertion and withdrawal of a stainless steel needle (Fig. 5).	Yes12)	No

DISCUSSION

Although dry needling and acupuncture are distinctly different in their application and proposed rationale, the common ground between the two therapies is invasive soft-tissue needling¹³⁾. The use of non-penetrating sham needling devices can help confirm a causation-based relationship between needling into myofascial trigger points (dry needling) or acupoints (acupuncture) and purported therapeutic outcomes^{1, 2)}. The present review identified five forms of placebo/sham needle devices, which fairly differ in their design and structures (Table 1). All five devices are considered sufficiently credible to be used in investigations of the effects of dry needling or acupuncture^{3,4,5,6,7,8,9,10,11,12)}. The Streitberger and Park devices are retractable, which means that when the blunt needle tip touches the skin, the needle shaft slides into a hollow needle handle (Figs. 1and 2). The Takakura and dry needle devices use the standard acupuncture needle, but the tip is blunt; thus, the tip impresses the skin rather than penetrating the dermis (Figs. 3and 4). The Ryodoraku device uses a standard acupuncture needle, but the tip of the needle stays sharp and never reaches the skin during insertion; thus, it will not activate mechanoreceptors in the skin and its blinding effectiveness could be diminished for patients with previous dry-needling/acupuncture experience (Fig. 5). Contrastingly, the first four devices mentioned above that minimally impress the skin (Figs. 1–4) cause a potential neurological response in the brain that is much weaker than that of real dry-needling or acupuncture; still, they are arguably not perfect inert placebo controls¹⁴⁾.

Fig. 1.

Streitberger sham device: The device is placed on the top of the skin using double-sided adhesive. The needle tip is blunt; the needle shaft telescopes into the handle when inserted.

Fig. 2.

Park sham device: The device is placed on top of the skin using double-sided adhesive. The needle tip is blunt, and the needle shaft telescopes into the handle when inserted.

Fig. 3.

Takakura sham device: The device is placed on top of the skin using double-sided adhesive. When inserted, the blunt needle tip impresses the skin. The needle guide tube is filled with sponge, which simulates soft tissues being penetrated.

Fig. 4.

Dry-needle sham device: The device is placed on the top of the skin by hand holding. The blunt needle tip impresses the skin when inserted.

Fig. 5.

Ryodoraku sham device: The device is placed on top of the skin using double-sided adhesive. The sharp needle tip does not touch the skin when inserted.

The Takakura device is the only tool specifically designed for double-blind masking, while the other four devices are meant for single-blind studies. However, the lack of standardization among sham needling devices complicates the comparison of results across different studies. To date, no research has been conducted to determine which sham device is the most optimal compared to others, or whether different sham devices have specific advantages when applied to different body regions. In other words, the choice of a sham needling device may influence the outcomes of a clinical trial.

Moreover, dry needling and acupuncture treatments produce two types of effects: specific effects, which are directly related to the invasive needling, and non-specific effects, which arise from the interactions between patients and therapists. Researchers need to manage the non-specific effects by minimizing physical and verbal interactions between patients and therapists, even though proper use of sham needling devices can considerably reduce the specific effects.

Conflicts of interest

The author has no conflicts of interest to declare.