Effect of acupuncture stimulation on trigger points in patients with lumbar back myofasciitis: a protocol for a single-centre, randomised, controlled clinical trial

Abstract

Introduction

Lumbar back myofasciitis (LBM) is a common condition caused by cold exposure, lumbar injuries or poor posture, leading to aseptic inflammation, fibrosis and chronic pain. While acupuncture stimulation of trigger points is widely used, clinical evidence supporting its efficacy remains limited. This study aims to evaluate the effectiveness and safety of acupuncture stimulation of trigger points in the treatment of LBM and to explore the underlying analgesic mechanisms.

Methods and analysis

This single-centre randomised controlled trial will be conducted at Acupuncture and Moxibustion Hospital of China Academy of Chinese Medical Sciences. A total of 60 participants will be randomly assigned to either the experimental group or the control group in a 1:1 ratio. The primary outcome measure will be the Visual Analogue Scale for pain, while secondary outcomes will include pressure pain threshold, ultrasound, infrared thermography and Roland-Morris Disability Questionnaire.

Ethics and dissemination

Ethics approval was obtained from the Ethics Committee of Xiyuan Hospital, China Academy of Chinese Medical Sciences (Approval No. 2024XLW007-2). The findings of this study will be published in peer-reviewed journals. Prior to participation, all eligible participants will be given informed consent.

Trial registration number

ITMCTR2025000258.

Correspondence to Dr Jun-ying Wang; [email protected]; Dr Rongjun Li; [email protected] and ZC are joint first authors.

STRENGTHS AND LIMITATIONS OF THIS STUDY

• The prospective randomised controlled trial design minimises selection bias.

• A long follow-up time point (3 months) allows for longitudinal assessment of outcomes.

• All interventions are administered by licensed physicians under standardised conditions.

• Due to the distinct nature of the interventions, blinding is not implemented.

• The single-centre recruitment approach limits population diversity, which may restrict the generalisability of the findings.

Introduction

Lumbar back myofasciitis (LBM) is a common soft tissue injury disease, often caused by factors such as overuse, poor posture or exposure to cold, leading to oedema, exudation and fibrous changes in the fascia (the connective tissue that surrounds muscles) and muscle tissue in the lumbar and thoracic regions, resulting in an aseptic inflammatory response.¹ Myofascial trigger points (MTrPs) refer to highly sensitive areas formed within the muscles or fascia, often resulting in tight, contracted nodules that cause localised pain or referred pain. LBM leads to impaired local blood circulation, muscle hypoxia and the accumulation of metabolic waste, which triggers muscle fibre tension and spasms, forming MTrPs.² If inflammation is not alleviated in a timely manner, LBM may progress to a chronic pain state, causing limited movement in the lumbar back and referred pain, significantly affecting the patient’s quality of life. LBM is showing a trend of occurring more frequently in younger individuals, and its prevalence has been increasing year by year.

The treatment principle for LBM is anti-inflammatory and analgesic therapy, which can be broadly categorised into pharmacological and non-pharmacological treatments. Pharmacological treatments lack highly targeted and specific medications. Currently, non-steroidal anti-inflammatory drugs or muscle relaxants are commonly used, which provide significant short-term effects but are not long-lasting. Physical therapies, such as ultrasound (US) and electrical stimulation, lack standardised parameters (including frequency, intensity and duration),³ resulting in high heterogeneity. Manual therapies, including acupuncture, massage and myofascial, are used to relieve the pain of LBM. Acupuncture therapy can relieve muscle tension and inflammation by stimulating MTrPs, thereby achieving analgesic and muscle relaxation effects.⁴ Acupuncture stimulation of MTrPs has a good analgesic effect,⁵ and using MTrPs as a target for intervention in LBM provides good clinical efficacy and high safety and can shorten the treatment course while reducing the recurrence rate of the disease. Studies have shown that acupuncture at MTrPs can effectively relieve myofascial pain in the lumbar back,⁶ reduce the Numerical Rating Scale scores in elderly patients with chronic lumbar back pain⁷ and provide significant short-term analgesic effects for patients with chronic non-specific lumbar back pain.⁸

MTrPs are significantly correlated to Traditional Chinese Medicine (TCM) acupoints, including primary channel acupoints, extra acupoints and Ah-shi points.^{9 10} However, there is currently no consensus on diagnostic criteria for MTrPs, nor is there a universally recognised standard for their localisation. Moreover, the clinical analgesic mechanism of acupuncture stimulation of MTrPs in treating LBM remains unclear.

MTrPs are classified into active and latent types and are closely related to changes in autonomic and metabolic activity.¹¹ The skin temperature at MTrPs changes due to local microcirculation and sympathetic nerve activity, which can be analysed using infrared thermography.¹² Despite this pathophysiological support, few studies have used infrared thermography to assess myofascial pain patients.¹³ US imaging technology can visualise and characterise the location of MTrPs, as well as the surrounding blood vessels and blood flow,¹³ providing more accurate detection results. Currently, there is a lack of studies that use infrared thermography and US for quantitative analysis of MTrPs in patients with LBM.

This study will divide patients with LBM into an acupuncture stimulation of trigger points group (experimental group) and a conventional acupuncture group (control group). The efficacy will be evaluated by observing changes in the Visual Analogue Scale (VAS) for pain, pressure pain threshold and Roland-Morris Disability Questionnaire (RDQ) functional scores before and after the intervention of the two different acupuncture techniques. Additionally, the number of trigger points will be assessed, and US will be used to evaluate the changes in the size of MTrPs before and after acupuncture. Infrared thermography will be employed to extract the average temperature value of the MTrPs. The study aims to explore the potential analgesic effects of acupuncture on myofascial muscles and surrounding blood vessels in the experimental group, and to clarify the possible mechanisms of acupuncture stimulation of MTrPs in pain relief.

Objective

To clarify the efficacy and safety of acupuncture stimulation of MTrPs in the treatment of LBM, and to explore the potential mechanisms of acupuncture intervention on MTrPs.

Methods and analysis

Study design

This study is a single-centre, randomised controlled trial (RCT). Voluntary patients who meet the inclusion criteria will be publicly recruited at the Acupuncture and Moxibustion Hospital of China Academy of Chinese Medical Sciences. It is expected that 60 participants will be enrolled and randomly assigned to the acupuncture stimulation of trigger points group or the conventional acupuncture group in a 1:1 ratio using simple randomisation. All patients must understand and sign an informed consent form prior to enrolment. The study protocol has been approved by the Ethics Committee of Xiyuan Hospital, China Academy of Chinese Medical Sciences (Approval No. 2024XLW007-2) and registered on the International Traditional Medicine Clinical Trial Registry Platform (Registration No. ITMCTR2025000258). The study is scheduled to begin on 1 January 2025, and end on 31 December 2025. ^{Figure 1} shows the trial flowchart, and ^{table 1} provides the schedule for participant recruitment, intervention and outcome assessments.

Table 1

Schedule for participant recruitment, intervention and outcome assessments

	Baseline	Treatment period		Follow-up period
Time point (week)	0	1	2	12
Enrolment
Subject screening	√
Informed consent	√
Medical history	√
Randomisation	√
Intervention
Trigger points group		√	√
Conventional acupuncture group		√	√
Assessments
Visual Analogue Scale	√	√	√	√
Pressure pain threshold	√	√	√	√
Ultrasound	√	√	√	√
Infrared thermography	√	√	√	√
Roland-Morris Disability Questionnaire	√	√	√	√
Satisfaction, compliance		√	√	√
Adverse events		√	√	√

Figure 1. Flowchart of the study.

Participants and recruitment

This study will include 60 eligible patients with LBM who visit the Acupuncture and Moxibustion Hospital of China Academy of Chinese Medical Sciences between 1 January 2025 and 31 December 2025 and meet the inclusion criteria.

Participants for this study will be recruited through outpatient visits or through advertisements and posters displayed on WeChat and in the hospital. Interested patients will be screened either via phone or in person and will provide their consent to participate in the study. The first participant was recruited on 8 April 2025.

Randomisation and allocation concealment

This study will use a simple randomisation method. The randomisation scheme, generated by a computer, will be managed by a designated person and securely stored in opaque envelopes. Apart from the study designer and the centre’s randomisation coordinator, no other researchers will be aware of the randomisation scheme. Patients will be assigned a number based on the order of their clinic visit. The clinical physician will request the random number and the corresponding treatment plan from the person responsible for the randomisation scheme based on the patient’s enrolment number. The 60 enrolled patients will be randomly divided into the acupuncture stimulation of trigger points group and the conventional acupuncture group, with 30 patients in each group. All researchers will receive training on research methodology guidelines before the trial begins and will strictly follow the principle of task separation throughout the study.

Blinding

Since there is a significant difference in the treatment methods between the acupuncture stimulation of trigger points group and the conventional acupuncture group, a double-blind study design cannot be applied. To mitigate this limitation, we will use a double-entry data method, where the entered data will be cross-checked for accuracy.

The individuals responsible for obtaining informed consent, screening participants, administering interventions and assessing outcomes will work separately and maintain confidentiality regarding patient information. After completing their tasks, they will submit the case report forms (CRFs) to the data managers at each site. The evaluators will not have access to group assignment details and will not be involved in the intervention or statistical analysis. Independent statistical experts, outside of the department, will conduct the statistical analysis without knowledge of the group allocations. The data manager at each site will collect, organise and submit the CRFs for data entry, which will be performed by a person not involved in the intervention or outcome evaluation.

Participants

Diagnostic criteria

According to the diagnostic criteria outlined in Myofascial Pain and Dysfunction¹⁴ and Traditional Chinese Medicine on Tendon and Muscle Injuries,¹⁵ the following diagnostic indicators for LBM are proposed:

• A history of strain or exposure to external factors such as wind, cold or dampness.

• Symptoms may include a sensation of coolness, aching or numbness in the skin, muscle spasms and restricted movement.

• The pain typically worsens in the morning, with changes in weather, or after exposure to cold. It is alleviated by movement or warmth. Prolonged immobility or excessive activity can trigger pain, which often recurs and becomes chronic.

• The presence of prominent trigger points or muscle spasm-induced painful nodules in the affected area. Pressing or pinching the affected muscle can provoke pain and radiating sensations and may also cause pain and muscle tightness in surrounding areas.

• X-ray examinations typically show no positive findings, helping to rule out conditions such as fractures or tuberculosis.

Inclusion criteria

• Meeting the above clinical diagnostic criteria for more than 3 months or experiencing recurrent episodes.

• Aged 18–65 years.

• Imaging studies have excluded other conditions causing lumbar back pain.

• Has not taken oral medications for treatment or placebo in the past month, and has not undergone acupuncture, nerve block or surgical treatment.

• The patient voluntarily signs the informed consent form.

Exclusion criteria

• Pregnant or breastfeeding women, individuals with psychiatric disorders or those planning pregnancy.

• Participants with severe underlying conditions such as cardiovascular, cerebrovascular, liver or kidney diseases.

• Participants with blood disorders like coagulation dysfunction, diabetes, severe lumbar disc herniation, fractures, bone tuberculosis or similar conditions.

• Participants in the acute phase of a first episode or those with excessive obesity.

• Participants with contraindications to acupuncture, such as skin infections, ulcers, scars and tumours or a history of thoracolumbar fractures or surgery within the past year.

• Participants who have participated in other clinical drug trials recently.

Removal criteria

• Participants who are unwilling or unable to continue with the clinical trial and request to withdraw from the study.

• Participants who do not explicitly withdraw from the study but fail to attend follow-up visits and are lost to follow-up.

• Participants with poor adherence who fail to follow the prescribed treatment plan or visit schedule, making it impossible to assess the effect, or when incomplete data affect the evaluation and outcomes.

• Participants who develop a skin infection in the lumbar region or experience worsening of symptoms during the treatment or those who require painkillers.

• Participants who independently use other interventions that may impact the study results.

Intervention

Trigger points group

All procedures were performed under sterile conditions, with clinicians wearing disposable sterile gloves. According to standard diagnostic criteria, a physical examination and palpation of the lumbar back regions were first conducted. Upon palpation, MTrPs were characterised by localised tenderness, palpable stiffness or tightness, and in some cases, nodules or taut band-like structures. Suspected MTrPs were marked on the skin using a marker, followed by routine disinfection.

A trained sonographer then conducted US scanning of each marked site (Aixplorer, SuperSonic Imagine, France). Areas showing hypoechoic changes with little detectable blood flow were preliminarily identified as MTrPs. These regions typically appeared as localised red foci on elastography imaging, further supporting their identification as trigger points. Skin markings were subsequently adjusted based on US findings to ensure accurate localisation.

After disinfecting the marked area with 75% alcohol, a disposable acupuncture needle (0.42 mm × 40 mm) was inserted at an oblique angle (approximately 60°) along the orientation of the muscle fibres, 0.5–1.0 cm lateral to the long axis of the US probe, with the probe’s midpoint aligned to the surface MTrPs location. Real-time US monitoring was used to guide the needle tip through the hypoechoic region corresponding to the MTrPs, avoiding vascular and neural structures. Once the needle reached the MTrPs, a series of three to five rapid and repeated lifting-thrusting manipulations were performed to induce effective mechanical stimulation. The treatment will be administered twice per week for a total of 2 weeks.

Conventional acupuncture group

Select a disposable acupuncture needle with a size of 0.25×40 mm. The patient will be positioned in the prone position, and acupuncture points including ShenShu (BL23), Weizhong (BL40), Dachangshu (BL25) and Yaoyangguan (GV3)¹⁶ will be selected (^{table 2}). After obtaining deqi, the needles will be retained for 30 min. The treatment will be administered twice per week for a total of 2 weeks.

Table 2

The location of the points

Acupoint	Location
BL23 (Shenshu)	At the lower back, 1.5 cun lateral to the posterior midline, beneath the spinous process of the second lumbar vertebra (L2).
BL40 (Weizhong)	At the back of the knee, at the midpoint of the popliteal crease.
BL25 (Dachangshu)	At the lower back, 1.5 cun lateral to the posterior midline, beneath the spinous process of the fourth lumbar vertebra (L4).
GV3 (Yaoyanguan)	At the lower back, in the depression below the spinous process of the fourth lumbar vertebra (L4), on the posterior midline.

Outcome

Primary outcome

Visual Analogue Scale (VAS)

The VAS is one of the most commonly used unidimensional tools for assessing pain intensity. The scale consists of a 100 mm line, with one end representing ‘no pain’ and the other end representing ‘the most intense pain imaginable’ or ‘pain at its extreme’. Patients are asked to mark a point on the line (with a ‘×’ or a ‘|’ for example) to indicate the level of pain they are experiencing at that moment.

Secondary outcomes

Pressure pain threshold (PPT)

Pressure pain threshold (PPT) measurement at the trigger point: a pressure device (FPIX25, Wagner Instruments, USA) with a contact probe (rubber tip) of 1 cm² area and a measurement range of 100 N/cm² (1000 kPa), with a sensitivity of 0.1 N, is used. The probe is applied vertically to the trigger point at a constant speed. If the participant verbally reports feeling pain, the PPT is read from the device’s digital panel. If the participant reports unbearable pain, the maximum tolerable pressure is recorded. The same procedure is repeated three times for each participant. Three measurements are taken at each site, and the values are recorded in kg/cm² from the device’s display. There is an approximate 30 s interval between each measurement.

Number of trigger points

The number of trigger points refers to the total count of active or latent trigger points identified during the clinical assessment. These points are typically located in muscles or fascia that are tender and may cause referred pain or muscle tightness. The number of trigger points can be recorded and tracked over time to assess the effectiveness of treatments such as acupuncture or other therapeutic interventions. The number of trigger points will be recorded as described above.

Ultrasound imaging

US imaging technology can be used to differentiate myofascial tissue containing MTrPs from normal myofascial tissue. The classic US features of MTrPs include well-defined hypoechoic elliptical areas and uneven internal echogenicity.¹⁷ Once the target region was identified in greyscale mode, the US system was switched to shear wave elastography (SWE) mode. The elastography settings included a sampling box of 25 mm × 25 mm and a measurement range of 0–50 kPa.

To ensure measurement accuracy, the probe was positioned parallel to the muscle fibres, sufficient coupling gel was applied, and a sterile probe cover was used to maintain aseptic conditions. No additional pressure was exerted during scanning. Participants were instructed to breathe slowly and evenly throughout the process. After image stabilisation for 3–5 s and maintaining probe stillness for an additional 2 s, the SWE image was frozen for quantitative analysis.

Measurements were performed on the frozen image, including the area, perimeter and stiffness of the hypoechoic elliptical regions. The maximum, minimum and mean elastic modulus values within the region of interest were recorded. Each MTrP was measured three times, and the average value was used for subsequent analysis.

Infrared thermography

Infrared thermography was conducted with a medical-grade infrared camera (ImageIR 8800, Infrarotsensorik Und Messtechnik, Germany), featuring a temperature range of 20.0–45.5°C, a display resolution of 0.01°C, and a measurement accuracy within ±0.3°C. The participants were tested in a space with a room temperature of 24.0–26.0°C, free from strong light, loud noise and electromagnetic interference. The room windows and doors were kept closed to maintain a stable indoor airflow. After entering the testing room, the participant was instructed to fully expose the back and waist area for examination. The infrared thermography camera was positioned approximately 80 cm from the trigger point or the control area. Two well-focused infrared thermographic images were captured. The average temperature of the trigger point was collected and extracted.

Roland-Morris Disability Questionnaire (RDQ)

The RDQ is a widely used tool to assess the level of disability caused by lumbar back pain. It consists of 24 self-reported statements regarding the patient’s ability to perform daily activities due to their back pain. The questionnaire includes items related to physical movements, such as bending, lifting, walking and sitting, as well as general discomfort or functional limitations caused by the pain. Each statement is answered with either ‘Yes’ (indicating the activity is difficult or restricted) or ‘No’ (indicating no difficulty with the activity). The total score is the number of ‘Yes’ responses, with higher scores reflecting greater disability. The RDQ is typically used to evaluate the functional impact of lumbar back pain and can be helpful for tracking the patient’s progress over time or assessing the effectiveness of treatments.

Safety assessment

This study involves acupuncture treatment for LBM, ensuring the safety of the acupuncture procedure. In case of special circumstances, the following measures will be taken:

• Severe pain: Comfort the patient, remove the needle and instruct the patient to relax and rest.

• Needle fainting: if needle fainting occurs, immediately stop the procedure, remove the needle, allow the participant to lie down and rest, and ensure that the room is ventilated.

• Needle retention: if the needle tip turns incandescent, quickly insert and remove the needle to prevent retention.

• Bent needle: replace the needle promptly if it becomes bent.

• Bleeding at the acupuncture site: apply pressure to the area with a sterile cotton ball for several minutes to stop the bleeding.

During the study, the use of pain-relieving medications, either traditional or modern, or any other therapeutic methods will generally be avoided. However, if the pain is severe enough to interfere with sleep, 300 mg of sustained-release ibuprofen (one capsule) will be given orally to relieve the pain. The intervention interval for acupuncture in this trial was ≥48 hours, whereas ibuprofen’s pharmacodynamic profile (half-life: 1.8–2.5 hours) indicates that its effects would not overlap with the therapeutic window of acupuncture. All rescue medication use was prospectively recorded in the CRFs, with precise documentation of timing and dosage. Participants will be categorised into non-users, low-frequency users (≤2 emergency doses/week) and high-frequency users (>2 doses/week; meeting withdrawal criteria). High-frequency usage triggered protocol-defined discontinuation to mitigate confounding risks. Permitting rescue medication aligns with the Declaration of Helsinki pain management principles (The World Medical Association guidelines). Restricting analgesics would have increased dropout rates due to uncontrolled pain (>15% projected), introducing selection bias. Our protocol achieved 0% dropout, demonstrating effective risk control.

If adverse reactions occur during the study, the researchers will assess the situation and determine appropriate treatment measures, including whether to discontinue the observation. In the event of a severe adverse event, the attending physician will immediately evaluate the situation and implement emergency interventions as needed—such as ECG monitoring, emergency medication or surgery—to stabilise the participant’s vital signs. All adverse events will be documented in the ‘Adverse Event Form’ and followed up with detailed records of the management process and outcomes until symptoms resolve or laboratory tests return to normal. The researchers will continuously monitor the health status of participants, evaluate subsequent treatment strategies and assess the potential relationship between adverse events and the study. For any serious adverse event, established ethical protocols will be strictly followed, and a comprehensive report will be submitted to the overseeing ethics committee.

No formal interim analyses are planned for this study due to the short duration of the intervention and follow-up period, as well as the relatively small sample size (60 participants). The risk associated with the intervention is minimal, and the primary and secondary outcomes are not expected to require early termination decisions based on interim efficacy or safety data. However, safety monitoring will be performed continuously throughout the trial by the study investigators. In the event of any serious adverse events or unexpected safety concerns, the principal investigator, in consultation with the institutional ethics committee, will assess the situation and determine whether early termination of the trial is warranted. Only the principal investigator and designated members of the research team will have access to any emerging safety data prior to the completion of the study. Any decision to suspend or terminate the trial prematurely will be made collectively by the principal investigator and the ethics committee.

Sample size

The sample size was determined by the primary outcome. According to the literature¹⁸ and preliminary clinical pilot study, the expected post-treatment VAS improvement in the experimental group is a mean of 4.40 with a SD of 2.00, while the control group is expected to have a mean improvement of 2.90 with a SD of 1.80. Assume that the ratio of the experimental group and the control group is 1:1, using a two-sided test with a significance level (α) of 0.05 and a power (1−β) of 0.80, and the required sample size is estimated by SAS V.9.4 software for 26 cases in each group. Allowing for a dropout of about 15%, the acupuncture group and the control group each required 30 cases, a total of 60 cases. The detailed sample size calculation and the intended statistical methods will be provided in the ^{online supplemental material 1}.

Data management and monitoring

Enrolled patients sign informed consent to the collection of patient data. All study cases must be observed and recorded according to the above protocol, with accurate completion of the CRFs. The general information of all participants (such as age, disease duration, BMI, vital signs, etc.) and data such as VAS scores, RDQ disability scores and adverse event records should be documented. Data recorders (who are unaware of the participant’s group allocation or intervention measures) must fill out the CRFs within the designated time frame. The accuracy, authenticity and completeness of the data must be ensured. If any corrections to the data are needed, a line should be drawn through the original data (without covering or erasing it). The corrected data should be written beside it, and the recorder should sign and date it. A designated person will be responsible for monitoring and recording the data, with statistical analysis conducted by a third party. All three parties will work independently without interfering with each other. The CRFs will be stored by a third-party individual who is not involved in the study (and who is unaware of the participants’ group allocations or interventions). After the trial is completed, the data management team will protect the database to prevent any further modifications by the researchers. Participant information will be de-identified and made public 1 year after the study report is disclosed, in order to enhance transparency.

Investigators must undergo a rigorous qualification certification process and maintain consistent personnel standards. The researchers will receive training, and standard operating procedures will be developed for various aspects of the study, including intervention procedures, CRFs completion details, outcome assessments and data management. Enhanced communication with participants will be emphasised to ensure a comprehensive understanding of and cooperation with the trial before randomisation. Potential factors that could impact the study will be identified and necessary improvements will be made to maximise participant compliance.

The final trial dataset will be accessible only to the principal investigator and designated members of the research team who are responsible for data analysis. All data will be anonymised to protect participant confidentiality. No contractual agreements exist that restrict the investigators’ access to the full dataset. The research team retains full ownership and control over the data, and all analyses and publications will be conducted independently without external influence from sponsors or third parties.

Patient and public involvement

Patients and members of the public were not involved in the design, development or conduct of this study. The research questions, intervention protocols and outcome measures were determined by the research team based on clinical experience and literature evidence, without direct consultation with patients regarding their priorities or preferences. Patient involvement first occurred during the recruitment phase, where eligible participants were informed and enrolled through outpatient clinics, hospital posters and social media platforms.

Participants did not contribute to the development of recruitment strategies or evaluation tools, nor were they asked in advance to assess the acceptability or burden of the intervention or time commitment required. While patient satisfaction and compliance will be measured during the study, these assessments were designed by the research team. Dissemination of results will primarily occur through peer-reviewed publications and anonymised data sharing; however, patients were not involved in decisions about what results to share, how or in what format.

We acknowledge the limited scope of patient and public involvement in this study and recognise its importance. Future research will aim to incorporate patient and public involvement more systematically by establishing patient advisory groups and involving them in shaping research questions, refining intervention strategies and co-producing dissemination materials to improve clinical relevance and patient-centredness.

Statistical analysis

The SPSS V.25.0 software will be used to establish the database and perform statistical data analysis, with a significance threshold defined as a two-sided p<0.05. Continuous variables will be described as mean±SD, or median (range) for normally distributed data, while categorical variables will be presented as frequencies (percentages).

For comparisons of pre-treatment and post-treatment outcomes within each group: paired t-tests or Wilcoxon signed-rank tests will be used for continuous data, and χ² tests or Fisher’s exact probability tests will be used for categorical data.

For comparisons of outcomes between groups: independent t-tests (with α correction as needed), analysis of variance or Kruskal-Wallis H test (with α correction as needed) will be used for continuous data, and χ² tests or Fisher’s exact probability tests (with α correction as needed) will be used for categorical data.

Considering that some participants may drop out during the intervention, both intention-to-treat (ITT) analysis (including all randomised participants) and per-protocol analysis (involving those who completed the intervention) will be conducted, with the primary focus on ITT for evaluation. For participants who are unable to adhere to the intervention or who drop out, a multiple imputation method will be applied to handle potential missing data under the assumption of ITT.

Ethics and dissemination

This clinical trial strictly adheres to the Declaration of Helsinki and relevant clinical research regulations in China. The study protocol has been approved by the Ethics Committee of Xiyuan Hospital, China Academy of Chinese Medical Sciences (Approval No. 2024XLW007-2). All participants will receive a thorough explanation of the study’s purpose, procedures and potential risks and will be required to provide written informed consent prior to participation (^{online supplemental material 2}). Data generated during the study will be available from the corresponding author upon reasonable request. The results will be published in international peer-reviewed scientific journals.

Discussion

LBM is a common soft tissue disorder characterised by non-infectious inflammation of the muscles and fascia in the lumbar back regions. In this study, we used LBM as the research model because it is one of the most commonly affected body areas. It is well established that MTrPs are the key areas for the effectiveness of acupuncture treatment for lumbar back myofascial pain. MTrPs are significantly correlated with acupuncture points in TCM.^{9 10} A hallmark of dry needling therapy is the elicitation of a local twitch response in the target muscle. Needling the trigger point can mechanically disrupt and deactivate the dysfunctional activity at the motor endplate of skeletal muscle motor neurons,¹⁹ effectively relieving pain, reducing muscle tension²⁰ and improving the long-term quality of life for patients with myofascial pain.²¹ Previous studies have shown that acupuncture at MTrPs provides good clinical outcomes for patients with lumbar back myofascial pain by reducing back pain symptoms.^6–8 A systematic review and meta-analysis, which included eight RCTs, indicated that acupuncture at MTrPs significantly outperformed the control group in reducing pain as measured by the VAS. The pain-relieving effect was more pronounced with longer treatment durations. Additionally, the acupuncture treatment group showed significantly improved lumbar function scores compared with the control group, suggesting that acupuncture helps improve the patients’ back function. Acupuncture at MTrPs can also reduce the number of MTrPs, transitioning them from an active to a latent state or causing them to subside,²² thereby reducing muscle stress²⁰ and improving mobility.²¹ Furthermore, acupuncture for lumbar back myofascial pain has shown high safety, with no severe adverse events reported. The mechanisms underlying acupuncture at trigger points are still unclear, and this study uses ultrasound, infrared thermography and other methods to explore these mechanisms.

US is an attractive non-invasive technique²³ that is widely used for identifying MTrPs.²⁴ US examinations are not only cost-effective but also provide an efficient means of assessing the structure of muscles, tendons and ligaments, particularly in distinguishing MTrPs from normal tissues.^{25 26} Currently, US technologies, such as greyscale imaging and elastography, are extensively used to evaluate the echotexture and mechanical properties of MTrPs. Greyscale US is primarily used to identify changes in muscle structure, while elastography measures tissue stiffness, helping to locate areas of increased tension in muscles.²⁷ US technology enables clinicians to clearly visualise muscle tissue and detect changes in echotexture, allowing targeted stimulation of trigger points, with significant advantages, especially in avoiding damage to surrounding muscles, nerves and other tissues.

US technology allows clinicians to observe the physiological and pathological changes in muscle soft tissues, particularly when combined with acupuncture treatment, significantly enhancing its efficacy. With US guidance, clinical procedures can be more precise, reducing the risk of damaging other important structures. Research²⁸ has shown that using musculoskeletal US to guide needle scalpel treatment for patients with LBM enables clear visualisation of the paravertebral muscle anatomy, avoiding inadvertent injury to tendons, nerves and other structures. This approach has a higher level of safety,²⁹ significantly improves clinical outcomes and reduces patient pain and complications.

Currently, there is no ‘gold standard’ for detecting MTrPs. Accurately locating hypoechoic nodules and understanding their spatial relationship with surrounding neurovascular structures is crucial.³⁰ On US imaging, MTrPs typically appear as focal hypoechoic nodules, and their blood flow patterns can help differentiate between active and latent MTrPs.³¹ However, some studies have shown that MTrPs may also appear hyperechoic, which is related to the morphology of surrounding tissues.³² In fact, due to the presence of multiple muscle fascicles oriented in different directions, muscle tissue is prone to artefact-related false hypoechoic appearances. In some cases, the extensive intramuscular connective tissue network can blur the peripheral boundaries of MTrPs, and oscillation techniques can be used to reduce interference from connective tissue.³³ In clinical practice, comprehensive indicators such as depth, thickness and stiffness³⁴ can be used to assess the characteristics of MTrPs for more precise localisation and treatment.³⁰ It should be emphasised that hypoechoic nodules should always be carefully palpated to confirm whether the patient’s pain can be accurately reproduced.^{35 36} Future research needs to establish more comprehensive protocols and parameter thresholds, which will further promote the application of US technology in trigger point therapy and improve treatment outcomes.

Infrared thermal imaging is a technique that uses infrared radiation to visualise the temperature distribution of the human body. When local pain occurs, the pain signal can be converted into a visual infrared thermal image temperature map. This technology has the advantages of high sensitivity, no radiation, ease of operation and good reproducibility and has been widely applied in clinical research. Using infrared thermal imaging diagnostic technology, it has been found that there is a temperature difference at the site of trigger points.³⁷ In patients with LBM, the distribution of trigger points in the back presents three states: high-temperature zones, low-temperature zones and mixed zones. The degree of pain and functional limitation in patients is positively correlated with the temperature of the high-temperature zone and negatively correlated with the temperature of the low-temperature zone.³⁸ The skin temperature pattern may show different characteristics based on the duration of muscle injury,¹¹ but there are distinct differences between healthy subjects and those with myofascial pain. The exact mechanism of this phenomenon is unclear, but it may be caused by metabolic disturbances in the trigger point area. Currently, there are few studies on MTrPs and infrared thermal imaging, and there is a lack of research evaluating the accuracy and reliability of infrared thermal imaging in diagnosing and assessing this condition. There is no consensus in the latest studies on the skin temperature patterns when MTrPs are present.³⁹ The use of infrared thermal imaging has shown promising results in identifying the thermal patterns of trigger points, and it could be a valuable auxiliary tool for evaluating and monitoring trigger point therapy.

This study selected classic and empirically effective acupoints for treating lumbar back pain, which can maximise the therapeutic effect. The primary outcome measure of this study is the VAS, a commonly used tool to assess pain intensity; however, it is also considered a subjective metric. Current research has found that not all identified MTrPs or nodules conform to the definitions provided by Simons et al.² If US can be effectively used to detect MTrPs, and combined with infrared thermography to obtain morphological data (such as temperature, area and thickness), it would not only demonstrate technical professionalism but also help improve treatment quality. This is of significant importance for the diagnosis and treatment of trigger point acupuncture and may contribute to understanding the underlying mechanisms of acupuncture at trigger points.

The study also includes a follow-up survey 3 months after treatment. Current evidence is unclear regarding the long-term efficacy of acupuncture, and follow-up results vary,^{40 41} making it difficult to determine the sustained effectiveness of the intervention over time.³⁶ It is hoped that the results of this study will offer insights into the long-term effects of acupuncture on pain relief. Of course, this study has certain limitations. It is a single-centre study with a relatively small sample size. Additionally, there are significant differences in treatment methods between the experimental and control groups, making it impossible to adopt a double-blind study design. The aim of this study is to evaluate the efficacy and safety of acupuncture at trigger points in treating LBM and to explore its potential mechanisms, providing a reference for future research.

Footnote

XS and ZC contributed equally.

Contributors XS and ZhC wrote the manuscript. ZiC, HZ and XP were responsible for participant recruitment and treatment; JY, YR, JZhao and JZhan assisted in the execution of the experiment and statistical design and RL and J-yW conceived the design of the trial and supervised the experiment. All authors have read and approved the final manuscript. XS and ZhC are co-first authors. RL and J-yW are co-corresponding authors. J-yW acted as the guarantor. During the preparation of this work, the authors used AI in order to improve language. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

Funding This work was supported by Scientific and technological innovation project of China Academy of Chinese Medical Sciences (CIZJS2025021), National Natural Science Foundation of China (No.82174220), Scientific and technological innovation project of China Academy of Chinese Medical Sciences (CIZIA2024-005) and the Fundamental Research Funds for the Central public welfare research institutes (ZZ-2023004, ZZ13-YQ-62, ZZ0908058). The study sponsor and funders do not have the right to design the trial or submit the report for publication of this project.

Competing interests None declared.

Patient and public involvement Patients and/or the public were not involved in the design, conduct, reporting or dissemination plans of this research.

Provenance and peer review Not commissioned; externally peer reviewed.

Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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