Odagi Satoru, et al.. Japanese Acupuncture and Moxibustion; 2022; Vol.16(1): 21-24

Short Communication

Establishment of a safe acupuncture method for the psoas andiliopsoas muscles using ultrasound imaging equipment
ODAGI Satoru, TANIGUCHI Hiroshi, FUKUDA Yasushi
KOYAMA Koji, TANAKA Shigeki, SAKAI Tomomi
Tokyo Ariake University of Medical and Health Sciences

Abstract
The iliopsoas muscle is composed of the psoas major and iliacus muscles. There are currently no objective method
regarding the safe angles and insertion depths of acupuncture needles for these muscles. This study aimed toinvestigate the safe insertion points of acupuncture needles into the psoas major and iliacus muscles using ultrasoundimaging equipment.
Sixteen healthy male volunteers participated in this study. An ultrasound system (LOGIQ-e, GE, USA) and a linear
probe (GE, USA) were used. Acupuncture needles measuring 60 mm were used for the psoas major muscle and 50
mm for the iliacus muscle. The distance, depth, and angle of the needles were measured at the point where muscle
contraction was obtained using an electro acupuncture stimulator (PicorinaⓇ, SEIRIN Co., Japan).
The insertion point for the psoas major muscle was 4.5±1.8 cm below the anterior superior iliac spine, 2.9±1.3 cm
lateral to the femoral artery, 78±14° vertically and 51±10° horizontally from this point, 4.7±0.4 cm deep, and theneedle was confirmed to be oblique medially. On the other hand, the iliacus muscle acupuncture point was located
2.2±0.4 cm medial to the anterior superior iliac spine, from which acupuncture was performed at 64±18° vertically,
58±9° horizontally, and 3.2±0.6 cm deep. In all subjects, we could confirm that the psoas major muscle moved inconjunction with the contraction of the iliacus muscle due to electro-acupuncture stimulation.
It was suggested that the above method could be safely applied to people whose age, body size, and sex are similar
to those of the subjects in this study.
Additionally, ultrasound images confirmed that electrical stimulation of the iliacus muscle induced contraction of
the psoas major muscle, suggesting that indirect contraction of the iliopsoas muscle, including the psoas major, byelectroacupuncture to the iliacus s muscle may be utilized as a treatment for low back pain.
.
Key words: psoas major, iliacus muscles, ultrasound imaging equipment, electro-acupuncture

I. Introduction
The iliopsoas muscle is a large compound muscle
composed of the psoas major muscle (PM) and iliacus
muscle (IM). Previous studies have shown that patientswith low back pain (LBP) have an increased lumbar
kyphosis angle due to the shortening of the iliopsoas
muscle1). Therefore, the iliopsoas muscle is one of themuscles that can cause LBP and can be a targeted muscle
for acupuncture treatment.
Cummings2) reported that an acupuncture insertion pointon the iliopsoas muscle is located approximately 2-3 cm
lateral to the femoral artery in the groin. Ball et al3). also
showed that the needle could be applied to the iliopsoas
muscle between 32.1±7.3 mm medial to the anterior
inferior iliac spine in the supine position. However, there
are no objective methods for a safe angle or penetration

depth for these points. This study aimed to investigate thesafe acupuncture insertion points for the PM and IM using
an ultrasound imaging system.
II. Methods
Sixteen male adults (mean±SD age; 23±1 years, height;
171±7 cm, weight; 70±9 kg, BMI; 24±3) participated inthis study. Those with a history of hip or gastrointestinal
disease were excluded from this study. The experiment
was conducted after written consent was obtained fromthe subjects following a full explanation of the protocol.
This study was approved by the Research Ethics Review
Committee of the Academic Research Council of Tokyo
Ariake University of Medicine. (Approval number: 295)
It has also been registered in the UMIN Clinical TrialsCorresponding author: Taniguchi Hiroshi, Tokyo Ariake University of Medical and Health Sciences, 2-9-1 Ariake, Koto-ku, Tokyo
135-0063, Japan
E-mail address: taniguchih@tau.ac.jp

22Odagi Satoru, et al.. Japanese Acupuncture and Moxibustion; 2022; Vol.16: 21-24

Registry (UMIN-CTR), a UMIN clinical registry system(UMIN study ID: UMIN000046826).
A diagnostic ultrasound system (LOGIQ-e, GE, USA)and a linear probe were used. The imaging conditions of
the ultrasound were: B mode, frequency 8 MHz, depth 4.5cm, and focus 1.5 cm to 2 cm. Moving ultrasound imagesof the PM and IM were also recorded. Linear probes wereplaced on the pulsating femoral artery and the anterior
superior iliac spine (ASIS). Single-use stainless steel
acupuncture needles (SEIRIN Co., Japan) with a diameterof 0.20 mm were used; 60 mm needles were used for PM,
and 50 mm needles were used for IM. Using theultrasound, the PM, femoral arteriovenous vein, andnerves were visualized in the inguinal region, and the IM,
peritoneum, and intestinal tract in the abdomen werevisualized to confirm the positional relationship betweenthese muscles and surrounding tissues. Based on theseimages, acupuncture needles were inserted and energized.
After confirming presence of muscle contraction withultrasound, the distance, depth, and angle of the needles
were measured. Differentiation between the PM and IM
was determined by the running of muscle fibers duringcontraction and was performed at the stimulus intensity
where painless muscle contraction was obtained with an
upper limit of 4 mA output from the electroacupuncture
stimulator (PicorinaⓇ, SEIRIN Co., Japan).

III. Results
Representative images of the PM and IM obtained using
the ultrasound recording system are shown in Figures 1and 2, respectively. Using these images as a reference, wewere able to confirm muscle contraction of the PM under
the following conditions: the insertion point was located4.5±1.8 cm below the ASIS and 2.9±1.3 cm laterally fromthe femoral artery. The conditions for acupuncture were
78±14° vertically and 51±10° horizontally from that point,
and 4.7±0.4 cm of the needles should be inserted obliquely
and facing medially. On the other hand, the acupuncture
insertion point for the IM was located 2.2±0.4 cm
medially from the ASIS, and the conditions foracupuncture were 64±18° vertically and 58±9°
horizontally from that point, and 3.2±0.6 cm depth.
Notably, we could confirm that in all subjects, the PM
moved in conjunction with the contraction of the IM
caused by electroacupuncture stimulation. As an adverse
event, transient radiating pain to the area innervated by thelateral femoral cutaneous nerve occurred in 3 cases during
iliopsoas muscle acupuncture, but this symptom resolved
immediately.

Figure.１ Acupuncture insertion point for the psoas major muscle (PM).
Figure 1-(A) shows a schematic diagram of the ultrasound image measurement. The gray dashed line indicates theprobe position. Typical ultrasound image of the upper right inguinal region (B). The muscle contraction of the PM
is obtained by acupuncture insert point of ④, which is located 4.5±1.8 cm below the ASIS and 2.9±1.3 cm
laterally from the femoral artery, at a 51±10 deg angle ⑩ and a 4.7±0.4 cm depth ⑪. Data are shown as mean ±standard deviation. ①: ASIS: anterior superior iliac spine, ②: inguinal ligament, ③ and ⑥: femoral arteria, ⑤:femoral nerve, ⑦: femoral vein⑧: psoas major muscle, ⑨: femoral head.

Odagi Satoru, et al.. Japanese Acupuncture and Moxibustion; 2022; Vol.16: 21-24

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Figure.2 Acupuncture insertion points for the iliacus muscle (IM).
Figure 2-(A) shows a schematic diagram of the ultrasound image measurement. The gray dashed line indicates theprobe position. Typical ultrasound image of the right anterior superior iliac spine (B). The muscle contraction of theIM is obtained by acupuncture insert point of (A)-④, which is located 2.2±0.4 cm medially from the ASIS, at a 58
±9 deg angle ⑧ and a 3.2±0.6 cm depth ⑨. Data are shown as mean ± standard deviation. ①and ⑤: ASIS:anterior superior iliac spine, ②: inguinal ligament, ③: femoral arteria, ⑥: iliopsoas muscle, ⑦: peritoneum.

IV. Conclusion
In this study, we identified stimulation points on the PM
and IM using ultrasound. Although electrical stimulation
may induce muscle contraction even if the acupunctureneedles do not reach the target muscles, we were able toestablish the points at which acupuncture stimulation canelicit contraction in these muscles. Since there were nofemale subjects or extreme outliers in terms of BMI, it isunclear whether the same method can be applied to all
patients. Therefore, we suggest that the above method canbe safely applied to people of similar age, body size, andsex as the subjects in this study. However, transientradiating pain to the lateral femoral cutaneous nerve may
occur during acupuncture of the iliopsoas muscle, inwhich case, the needle should be reinserted.
The following points should be noted when acupunctureneedles are inserted into the PM and IM: for PM, needles
should be inserted obliquely from the femoral artery to themedial side to avoid the femoral artery and femoral nerve;
for IM, needles should be inserted obliquely from 2 cm
medial to lateral (toward the iliac crest) from the superior
anterior iliac spine to avoid the peritoneum while
capturing the muscle belly. To insert the needles into themuscles, the length of the needles should be 60 mm for
PM and 50 mm for IM. The method presented here avoids
the risk of needling internal organs, blood vessels, andfemoral nerves.

Finally, the needle insertion location of the PM was close
to the perineum, which may have caused most patients torefuse treatment. The insertion points of the IM located at
the ASIS are relatively more acceptable, and ultrasoundimaging confirmed that electrical stimulation of the IM
induces muscle contraction of the PM, and indirectcontraction of the PM by electroacupuncture of the IM
could be used as a treatment for back pain.
Acknowledgments
The authors are deeply grateful to Professor Yoshihisa
Koga, Professor Fumiko Yasuno, Assistant Professor
Hideki Fujimoto, Assistant Professor Oyunchimeg
Chuluunbat and Assistant Professor Yuto Matsuura of theTokyo Ariake University of Medical Science Graduate
School of Health Sciences for their assistance in this study.
We would like to thank Editage (www.editage.com) for
English language editing.
The authors have no conflicts of interest directly relevantto the content of this article. The results of this manuscript
are based on excerpts from a manuscript submitted inJapanese as a master’s thesis to Tokyo Ariake Universityof Health and Sciences. I certify that a part of this paper
was presented at the annual congress of the Japan Societyof Acupuncture and Moxibustion in Kyoto (69th, 2020)and Fukuoka (70th, 2021), but the entire paper has notpreviously been published.

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Odagi Satoru, et al.. Japanese Acupuncture and Moxibustion; 2022; Vol.16: 21-24

References
1) Christie HJ, Kumar S, Warren SA. Posturalaberrations in low back pain. Arch Phys Med Rehabil
1995:76(3):218-24
2) Cummings M. Referred knee pain treated withelectroacupuncture to iliopsoas. Acupunct Med
2003;21(1-2):32-5.
3) Ball AM, Finnegan M, Koppenhaver S, et al. The
relative risk to the femoral nerve as a function ofpatient positioning: potential implications for trigger
point dry needling of the iliacus muscle. J Man ManipTher 2019;27(3):162-71.