Effect of Combined Electrowarm Dry Needling on Postpartum Pelvic Girdle Pain: A Randomized Controlled Study

Summary

This protocol describes a randomized controlled trial evaluating the efficacy of combined electrowarm dry needling in reducing pelvic girdle pain and improving functional status in postpartum women.

Abstract

Postpartum pelvic girdle pain (PGP) is a common complication after childbirth, with limited safe and effective treatment options due to the risks of pharmacological interventions in postpartum women. This study aimed to evaluate the efficacy and safety of combined electrowarm dry needling therapy targeting myofascial pain trigger points (MTrPs) for alleviating PGP in postpartum women. A total of 92 postpartum women with PGP were randomly assigned to a treatment group (n = 46) receiving electrowarm dry needling on MTrPs 5x per week for 4 weeks plus standard postpartum care; a control group (n = 46) received only standard postpartum care. The intervention was conducted 5x a week for 4 weeks, with pain assessed by the Visual Analog Scale (VAS) at 1/3/7 days post intervention, disability by the Oswestry Low Back Disability Questionnaire (OLBPQ), and quality of life by the Nottingham Health Profile (NHP) at 1 month and 3–5 months post intervention. Pubic symphysis distance was measured by B-mode ultrasound at follow-up. Baseline characteristics showed no significant differences between groups (all P > 0.05). The treatment group demonstrated significantly reduced VAS scores at 3 and 7 days post intervention (P = 0.029 and P < 0.001, respectively), and marked improvements in OLBPQ scores at 1 week and 4 weeks (P < 0.001). NHP scores indicated enhanced quality of life in the treatment group, particularly at 3–5 months follow-up (P < 0.001), and the pubic symphysis distance was significantly decreased (P. < 0.01). No serious adverse events were observed in the treatment group, with only two cases of mild local soreness. Combined electrowarm dry needling therapy targeting MTrPs is a safe and effective non-pharmacological intervention for reducing pain and disability and improving quality of life in postpartum women with acute PGP in this single-center study.

Introduction

In postpartum, pelvic girdle pain (PGP) is deemed a public health concern, considering its significant impact on the quality of life of pregnant women and their infants^1,2. PGP is typically marked by continuous discomfort in the bones and muscles surrounding the pelvic ring, and this can manifest either during pregnancy or after childbirth^3,4. Epidemiological evidence indicates that PGP affects 20% to 70% of pregnant women globally, with 8.5% to 37% continuing to experience persistent symptoms into the postpartum period⁵. It is defined as pain between the posterior iliac crest and the gluteal pleat, especially the sacroiliac canal knot^3,4,5.

As pregnancy progresses, this pain usually intensifies, and it can affect activities of daily life in pregnant women such as weight bearing, sitting, and walking. It may also lead to physical inactivity and insomnia in women after pregnancy⁶. Limited perinatal and postpartum self-care has been noted to have a detrimental effect on maternal well-being and can even negatively influence postpartum health⁶. Prenatal and postpartum pelvic girdle pain have been found to be linked to an increased risk of postpartum depression⁷. Up to 70% of women report depressive symptoms during pregnancy, and 10–16% meet the criteria for major depression⁸. Additionally, the occurrence of PGP has been shown to negatively impact infant development⁹. Therefore, the primary objective is to determine safe and effective techniques for managing PGP in clinical settings.

To effectively manage PGP, the current international guidelines advocate for the utilization of pharmacological interventions². Various pharmacological treatments, including acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), muscle relaxants, opioid analgesics, epidural steroids, anticonvulsants, antidepressants, and corticosteroids, may be administered as interventions. Most of these medications can provide pain relief, but they also have certain restrictions and carry the risk of significant adverse effects. The aforementioned adverse reactions consist of somnolence, vertigo, dependency, hypersensitivity reactions, reversible impairment of hepatic function, and damaging consequences on gastrointestinal health¹⁰.

The use of drugs due to breastfeeding may affect the fetus. Conversely, it is often observed that the patients have a specific apprehension toward conventional spinal surgery and experience local anatomical damage and postoperative pain. As a result, there has been a steady rise in the use of diverse therapeutic modalities, such as chiropractic therapy, physiotherapy, massage, exercise, herbal medicine, and acupuncture, for PGP management. Many practitioners are now turning to dry needling as a means of addressing pain-related disorders without the use of medication¹¹. Our primary recommendation is to implement a combined approach that incorporates both warm and electro dry needle therapy as an effective means of treating PGP in its early stages.

We advocate for a treatment that combines warm and electro dry needle therapy on myofascial pain trigger points (MTrPs), which is used for the treatment of PGP. Janet Travell first introduced the term “MTrPs” in 1942¹², which can be categorized into two types: latent and active MTrPs¹³. Generally, a degree of injury in skeletal muscle can result in the development of latent MTrPs, which may go unnoticed for a significant duration and either be asymptomatic or cause only mild localized discomfort¹⁴. Latent MTrPs usually do not cause symptoms, but when they are compressed, they can cause pain or discomfort to reappear¹⁵. Apart from local pain, other typical symptoms associated with MTrPs include muscle weakness and limited range of motion. The combination of these symptoms can have a significant impact on quality of life, mood, and overall health.

A range of treatment options exists for MTrPs, including stretching, massage, acupuncture, injections, and instrument-based modalities such as transcutaneous electrical nerve stimulation, ultrasound, infrared, and laser treatment. Nevertheless, dry needling remains the most widely utilized method. Research has shown that incorporating MTrPs in the treatment of low back pain can have promising therapeutic outcomes with minimal side effects^16,17. However, there is a dearth of published studies on the use of MTrPs in patients with postpartum PGP. Previous studies have confirmed the efficacy of single dry needling for musculoskeletal pain¹⁸, but no published research has investigated the therapeutic effect of combined electrowarm dry needling targeting myofascial trigger points on postpartum PGP, nor has it explored the mechanism of this combination therapy on lumbopelvic stabilization and pubic symphysis recovery.

The objective of this paper is to analyze the effectiveness of a combined treatment approach involving warm and electro dry needling for lumbopelvic stabilization, pain management, disability reduction, and quality-of-life enhancement in postpartum women with PGP. Our hypothesis is that administering this treatment will result in significant improvements in pain reduction, disability reduction, quality of life, and strengthening of lumbopelvic stabilization in postpartum women with PGP.

Protocol

Study design
This study was a single-center, randomized controlled trial (RCT) conducted at Boai Hospital of Zhongshan, China. The Ethics Committee of Bo'ai Hospital in Zhongshan (Zhongshan Maternal and Child Health Hospital) reviewed and approved this clinical protocol (KY-2023-005-03). The study was registered in the Chinese Clinical Trial Registry (ChiCTR2400081932) on March 15, 2024. In this study, the treatment process, therapeutic principles, potential adverse reactions, and two intervention options were explained in detail to the patients, and treatment was administered only after obtaining their signed informed consent. The Department of Information Technology at Boai Hospital in Zhongshan provided technical support for data analysis in this study.

Patient selection (inclusion/exclusion)
Patients were included in the study if the pain occurred during pregnancy and for a period after delivery (within 6 months postpartum); the pain was located between the posterior iliac crest and the gluteal fold, particularly near the sacroiliac joint (SIJ); the pain originated from or radiated to the medial aspect of the proximal thigh and was accompanied by pain in the pubic symphysis; the patient's tolerance for standing, walking, and sitting was reduced; lumbar spine pathologies had been ruled out by lumber X-ray and MRI; they voluntarily participated in the study and signed the informed consent form. In addition to clinical criteria, diagnostic confirmation was supported by imaging findings. B-mode ultrasound assessment demonstrated pubic symphysis separation and characteristic features of myofascial trigger points (MTrPs), including hypoechoic regions or localized areas of increased muscle thickness within taut bands.

Patients were excluded from the study if there was a history of lumbar or sacral tuberculosis, infection, significant trauma, fracture, surgery, or malignant tumors; diagnosed osteoporosis or hip joint disease; confirmed diagnosis of rheumatic diseases; pelvic or lumbosacral soft tissue infection; coagulation disorders; or severe systemic diseases; long-term use of nonsteroidal antiinflammatory drugs or dependence on opioid medications within 1 month before enrollment; cognitive or psychiatric disorders that affected the ability to cooperate with study examinations and clinical treatments; refusal to accept the intervention measures or inability to complete the entire follow-up process. Where necessary, pelvic X-ray imaging was used to exclude structural abnormalities such as fracture, dislocation, or degenerative changes.

Randomization and group allocation
Participants who met the inclusion criteria and signed the informed consent form were randomly assigned to the treatment or control group using a random number table. A third-party statistician generated the random sequence using a random number table in spreadsheet software, and allocation concealment was implemented with sealed opaque envelopes. The envelopes were numbered in sequence according to the random sequence, and the research nurse opened the corresponding envelope according to the participant's enrollment order to complete the group assignment, with the statistician and intervention implementers blinded to the random sequence. A total of 92 postpartum women were randomly allocated to either the treatment group (n = 46) or the control group (n = 46). All baseline clinical parameters of the participants were examined and recorded before the formal intervention to ensure the comparability of the two groups.

Intervention procedure
All postpartum women were advised to appropriately wear a pelvic belt for compression and stabilization, ensure adequate rest, maintain proper posture, and avoid harmful habits. Normal activities may be resumed after symptom resolution, supplemented by core muscle stability training (i.e., conventional postpartum rehabilitation management). The core muscle stability training was conducted as follows: patients were asked to stand on one foot, keeping the torso and both upper limbs as straight as possible, with the contralateral limb held straight. Balance was to be maintained for 5 s, then both upper limbs and the contralateral limb were raised while contracting the lower back muscles, the posture was held for 5 s, then relaxed. The subjects were asked to switch to the other leg, repeating the same sequence, 10 repetitions on each side, with the entire session lasting approximately 2 min. This exercise could be performed 2x daily, at least 6x per week, for a total training duration of 12 weeks. All operators performing the intervention received standardized training prior to study initiation to ensure consistency in ultrasound-guided MTrP localization and needling technique.

Electro and warm dry needle combined treatment (treatment group)
The treatment group received combined electrowarm dry needling therapy targeting MTrPs based on conventional postpartum rehabilitation management, with the intervention conducted 5x a week for 4 consecutive weeks. The specific treatment process was as follows: The patient was asked to lie on the comfortable treatment bed in a prone or side-lying position and guided to relax the whole body to the maximum extent.

Acupoints were located and selected as follows^19,20: MTrPs were localized under B-mode ultrasound guidance, combined with manual palpation to identify taut bands and tender points with referred pain. The primary trigger points were confirmed at the pubic symphysis and surrounding region, the medial aspects of both proximal thighs, the sacroiliac joints, the sacrococcygeal area, and the buttocks. Throughout the entire treatment course, this area of greatest pain would serve as the primary and priority treatment site. Ultrasound imaging was further used to confirm the presence of MTrPs, which were identified as hypoechoic regions or areas of increased muscle thickness within a taut band. The location and number of MTrPs were recorded to ensure consistency of treatment targeting across sessions.

Disinfection of the operator’s hands and the affected skin of the subjects was done using 75% alcohol. Care was taken to ensure that the treatment avoided skin damage, nodules, and areas and to keep the patients warm and emotionally relaxed during treatment.

Under ultrasonographic guidance, the sterile acupuncture needle was precisely inserted into the patient's myofascial trigger points (MTrPs) at a 30–45° angle using lifting, thrusting, twisting, rotating, and other manipulative techniques (frequency 1–2x/s). The needle depth was 1–2 cm according to the thickness of the local muscle tissue, avoiding blood vessels and nerves. The procedure aimed to elicit characteristic sensations such as soreness, numbness, distension, pain, or heaviness, and/or to induce local tissue changes, including tightness, swelling, or fasciculation (muscle twitching).

The inserted acupuncture needle was connected to the electroacupuncture and warm needling integrated apparatus, the waveform of the instrument set to continuous wave, frequency to 50 Hz, and current intensity 0.5 mA²¹. Electrowarm dry needling was performed for 30 min at a time, 5x a week for 4 consecutive weeks.

Control group.
The control group consisted of patients who were randomly assigned and received standard postpartum care with the same baseline characteristics as the treatment group. All participants were informed of the two intervention options before randomization and signed their informed consent, eliminating selection bias caused by refusal of intervention. The control group received only conventional postpartum rehabilitation management (wearing the pelvic belt, rest guidance, posture correction, and core muscle stability training) without electrowarm dry needling therapy. The core muscle stability training of the control group was standardized and supervised by a professional rehabilitation therapist, with two sessions per day (15 min per session) and 6 days per week for 12 weeks. Adherence to training was monitored by weekly face-to-face follow-up and exercise logs, with the compliance rate recorded as the ratio of actual training sessions to planned sessions. The average compliance rate of the control group was 96.3%, and no participant was excluded due to low compliance.

Outcome measurements
Upon admission, the baseline demographic and clinical characteristics of the participants were recorded in detail. All outcome indicators were assessed by professional assessors who were blinded to participants' group allocation, and the same assessor was responsible for the follow-up assessment of each participant to ensure consistency in assessment standards. The specific assessment time points included baseline (1 day before the start of intervention); short-term post-intervention (1 day, 3 days, 7 days after the start of intervention); medium-term follow-up (1 month after the end of intervention); long-term follow-up (3–5 months after the end of intervention). The primary and secondary outcome indicators were assessed at different time points, depending on the indicators' clinical characteristics. To ensure diagnostic consistency and measurement reliability, two independent assessors were trained using standardized criteria prior to study initiation. Inter-assessor agreement was evaluated using Cohen’s kappa coefficient. The agreement for PGP diagnosis was κ = 0.86 (95% CI: 0.78–0.94), indicating almost perfect agreement, and for MTrP localization was κ = 0.82 (95% CI: 0.74–0.90), indicating substantial to almost perfect agreement.

Primary outcomes.
Disability
The current investigation employed the validated and reliable Turkish adaptation of the Oswestry Low Back Disability Questionnaire (Oswestry LBPQ, OLBPQ) to evaluate functional impairment caused by PGP^22,23. We used the adapted version of the questionnaire from China²³. The questionnaire comprised 10 subgroups and was scored on a scale of 0 to 5. Subgroups of this survey included specific sections that evaluated pain levels, ability to lift and carry items, walking, sitting, standing, sleeping, sexual activity, traveling, and social interactions. However, sexual activity was excluded from this study. The questionnaire produced a comprehensive score that ranged from 0 to 45. Each item still had a score range of 0–5, and the total score range was adjusted to 0–45. The scores of each item were added up without weighting, and the total score was directly obtained. The final total score was classified as mild functional impairment (0–9 points), moderate functional impairment (10–24 points), and severe functional impairment (25–45 points).

Pain
The Visual Analog Scale (VAS) was used to assess pain intensity^24,25. It is a unidimensional measurement tool that comprises a 10 cm (100 mm) horizontal line. More specifically, this line is delineated by two verbal descriptors positioned at opposite ends, denoting the contrasting ends of the pain spectrum: "complete absence of pain" and "the utmost intensity of pain imaginable." We used the Chinese adapted version and established a comprehensive scoring system ranging from 0 to 100. This system involved measuring the distance between the "pain-free" reference point on the 10 cm line and the patient's marked point using a ruler (in centimeters). The score increases as the pain intensity increases. The core of the VAS scale is a 100 mm straight line, without specific items, and is scored only through visual markers. The calculation rule is simple and easy to understand: the evaluator drew a 100 mm straight line, marking "complete pain-free" at the left end (0 mm) and "the most intense pain imaginable" at the right end (100 mm). The patient marked their own pain position on the straight line, and the evaluator measured the distance between the marked point and the left end with a ruler. This value was the final score, with a score range of 0 to 100 points. 0 points = completely pain-free, 1–30 points = mild pain, 31–60 points = moderate pain, 61–100 points = severe pain; the higher the score, the more obvious the pain intensity.

Secondary outcomes.
Health-related quality of life
We employed the transcultural adaptation of the Nottingham Health Profile (NHP) to measure the health-related quality of life²⁶. The NHP is a comprehensive questionnaire developed for the purpose of assessing an individual's perceived health issues and their impact on daily functioning. The survey had a total of 38 questions consisting of six sub-sections: lack of energy (three items), pain (eight items), emotional reaction (nine items), sleep disturbance (five items), social isolation (five items), and physical mobility (eight items). Participants were required to answer the assessment questions using a simple "yes" or "no" response. Each sub-section was then assigned a score, with a minimum score of 0 and a maximum score of 100. The higher the score, the worse the patient's health-related quality of life is, and the more significantly they are affected by symptoms such as pain.

Pubic symphysis distance.
The pubic symphysis distance is mainly used to assess the stability of the pelvis and to evaluate the impact of intervention measures on the repair of the pelvic structure. We conducted precise measurements using B-mode ultrasound, instructing patients to lie supine, with their legs naturally straightened and the pelvic and lower abdominal muscles relaxed to avoid interference from muscle tension. The ultrasound probe was placed perpendicular to the midline of the pubic symphysis, clearly showing the coronal section of the pubic symphysis gap, measuring the maximum distance between the bony margins on both sides of the pubic symphysis, repeating the measurement 3x each time, and taking the average of the three measurements as the final pubic symphysis distance value, with measurement accuracy precise to 0.1 mm. Alongside other secondary outcome indicators, we conducted tests at baseline (1 day before the intervention began), mid-term follow-up (1 month after the intervention), and long-term follow-up (3–5 months after the intervention), with all measurements conducted by ultrasound physicians who had undergone standardized training. The reference range for the pubic symphysis distance in normal postpartum women is 0.3–0.5cm. If the distance is greater than 0.5 cm, it indicates pubic symphysis separation, and the greater the distance, the poorer the stability of the pelvic structure, and there is a positive correlation with the degree of PGP pain and functional impairment. By comparing pubic symphysis distance at different time points and between the two groups, we evaluated the promotion effect of combined electrothermal dry needle therapy on pubic symphysis recovery in postpartum PGP patients.

Pelvic girdle muscle strength.
Pelvic stabilizing muscle strength is the core factor for maintaining pelvic stability and alleviating PGP. As a secondary outcome indicator, it was used to evaluate the effect of intervention measures on the recovery of muscle function in the pelvic region. It was assessed using manual muscle testing (MMT) combined with muscle strength grading standards. We focused on the core muscle groups of the pelvic belt, including the gluteus maximus, gluteus medius, iliopsoas, piriformis, and pelvic floor muscles. These muscles are all key muscles for maintaining pelvic stability and controlling pelvic movement. A decrease in their muscle strength will directly aggravate the symptoms and functional impairments of PGP. When evaluated by a professional rehabilitation therapist using the MMT five-level grading method (Lovett grading method), the grading was based on the patient's ability to contract the muscles against resistance.

The grading criteria were as follows: 0 level (no contraction): The muscles have no contraction movement; 1 level (weak contraction): The muscles can be felt to have a weak contraction, but there is no joint movement; 2 level (movable without resistance): The muscle contraction can drive the joint to complete full-range movement but cannot resist gravity; 3 level (able to resist gravity): The muscle contraction can drive the joint to complete full-range movement and cannot resist its own gravity but cannot resist additional resistance; 4 level (able to resist partial resistance): The muscle contraction can resist its own gravity and some additional resistance, completing full-range joint movement; 5 level (normal muscle strength): The muscle contraction can resist its own gravity and the maximum additional resistance, and the joint movement is smooth, with normal muscle strength.

Consistent with the time point of the pubic symphysis distance measurement, we conducted evaluations at the baseline (1 day before the intervention began), the mid-term follow-up (1 month after the intervention), and long-term follow-up (3–5 months after the intervention). The same rehabilitation therapist conducted all follow-up evaluations for the same patient to avoid evaluator bias. The final assessment of pelvic belt muscle strength is based on the average grading of all core muscle groups. The higher the grading, the stronger the pelvic belt muscle strength and the better the pelvic stability. At the same time, the correlation between pelvic belt muscle strength and improvement in PGP symptoms was analyzed, and the effect of combined electrothermal dry needle therapy on enhancing pelvic belt muscle strength was evaluated.

Statistical analysis
Our sample size calculation was based on the methodology outlined in Oktaviani et al., which assumes a normal distribution of response differences between matched pairs of pregnant women with PGP, with a standard deviation of 1.64^27,28. The sample size was estimated by assuming a mean paired difference of 1.11 and calculating the number of participants required to identify this effect with 80% power against a null hypothesis of no difference. The Type I error probability associated with this test of the null hypothesis was 0.05. Based on the above parameters, the required sample size for each group was 40 cases; with a 15% loss to follow-up rate, 46 cases were included in each group, for a total sample size of 92 cases.

Data were analyzed using both per-protocol (PP) and intention-to-treat (ITT) approaches. The primary analysis was the PP analysis, which included participants who completed the full intervention and follow-up (treatment group, n = 45; control group, n = 40). A supplementary ITT analysis was conducted for all 92 randomized participants, with missing outcome data handled using last observation carried forward (LOCF). The results of the ITT analysis were consistent with those of the PP analysis, supporting the robustness of the findings.

Descriptive statistics are presented as mean ± standard deviation (SD). The normality of continuous variables was assessed using the Kolmogorov–Smirnov test, which indicated that most variables were non-normal. Consequently, between-group comparisons were performed using the Mann–Whitney U. test for continuous outcomes and the chi-square test for categorical variables. Statistical analyses were performed using a standard statistical software package. A two-tailed P value < 0.05 was considered statistically significant. Data analysis was conducted using professional statistical analysis software. The means and standard deviations were computed for every variable. Using a Kolmogorov-Smirnov test, it was determined that the data did not follow a normal distribution. The Cronbach's alpha coefficient is 0.88 for these tools, including the Visual Analog Scale (VAS), the Oswestry Low Back Disability Questionnaire (Oswestry LBDQ), and the Nottingham Health Profile (NHP).

Results

Study participants.
The execution of this study was conducted in accordance with a randomized controlled procedure (Figure 1). A total of 100 pregnant women participated in the screening. Then, six women were excluded from the study since they failed to meet the predetermined inclusion criteria, while an additional two women opted not to participate in the study. In the current investigation, 92 participants were randomly assigned to one of two experimental grou...

Discussion

Study limitations
This study has certain limitations that need to be acknowledged. First, although the researchers who followed the patients and collected the data were unaware of the grouping (assessor blinding), it was impossible to completely blind the therapists who conducted the electrowarm dry needling intervention due to the nature of the clinical operation, which may have introduced a certain degree of performance bias. Second, this study is a single-center trial with a moderate sample size...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Disposable Sterile Acupuncture Needles	0.25 mm x 40 mm, 0.3 mm x75 mm	Suxiezhuzhun: 20162270588	Suzhou Acupuncture Products Co., Ltd.
GraphPad software	GraphPad Prism 9.0		Graphpad Software Inc, California,USA
Portable color doppler ultrasound system	Anesus TE9	Yuexiezhuzhun 20212060876	Shenzhen Mindray Biomedical Electronics Co., Ltd
SPSS software	SPSS 27.0		IBM Corporation, New York, USA
Warm Needle Electroacupuncture Therapy Device	HT-2	Suxiezhuzhun 20212201551	Jiangsu Yunlian Intelligent Medical Equipment Co., Ltd