Ultrasound-GuidedMyofascialHydrodissectionforMyofascialPainSyndrome:ARetrospectiveStudyonPainReliefandFunctionalImprovement

Myofascial pain syndrome (MPS) is an extremely common chronic pain condition, with a lifetime prevalence estimated at approximately 85%. It is caused by myofascial trigger points—hyperirritable nodules within muscle fibers that produce local or referred pain, restrict range of motion, and cause muscle weakness. Despite its prevalence, MPS remains challenging to treat. Non-invasive approaches like physical therapy, stretching, and massage typically offer only temporary relief without addressing the underlying trigger points.

More invasive options such as dry needling and trigger point injections can cause pain, discomfort, muscle tears, and inconsistent results. Alternative therapies including botulinum toxin, lidocaine, steroids, and platelet-rich plasma carry risks of infection, muscle weakness, and other side effects. A key limitation of conventional treatments is the lack of reliable, objective methods to accurately locate trigger points, leading to poor precision and variable outcomes. There is growing interest in imaging-guided techniques, particularly ultrasound, to improve accuracy and safety.

Ultrasound-guided myofascial hydrodissection technique (UMHT) is an innovative approach that combines ultrasound imaging with electromyography to precisely locate trigger points, then injects saline solution to release perimuscular and perimysial adhesions, deactivate trigger points, and promote healing. This study aimed to evaluate whether UMHT could safely and effectively reduce pain and improve function in patients with MPS.

This was a retrospective cohort study conducted at a university-affiliated clinical research institution in China. The researchers reviewed medical records of 28 patients diagnosed with MPS who were treated between September 2023 and December 2023. All patients received two sessions of UMHT, one week apart, with each session lasting approximately 15 minutes. The procedure involved identifying myofascial trigger points through manual palpation and clinical symptoms, then using ultrasound guidance to inject 5 mL of 0.9% normal saline into each trigger point and surrounding myofascial tissues using a 22G needle.

The total volume per patient was 10 mL of saline. The goal was to release perimuscular, perimysial, and extramuscular attachments around the trigger point to deactivate it and restore myofascial function.

Pain and functional outcomes were assessed at baseline, 24 hours, 2 weeks, 1 month, and 3 months after treatment. An independent physician who was unaware of treatment details conducted all follow-up assessments to minimize bias. The primary outcome measures were the Visual Analogue Scale (VAS) for pain severity, the McGill Pain Questionnaire for sensory and emotional aspects of pain, and the Oswestry Disability Index (ODI) for lower back function. The study used nonparametric statistical methods (Friedman's ANOVA) because the data were not normally distributed.

Effect sizes were calculated using Cohen's d, rank-biserial correlation, and standardized response mean to assess clinical significance.

The 28 patients had a mean age of 45.2 years and had experienced pain for an average of 18.4 months. The lower back was the most common pain site (42.9%), followed by the neck (35.7%) and shoulder (21.4%). All patients completed the study with no dropouts and no adverse events reported.

Pain reduction was substantial and statistically significant. VAS scores dropped from a baseline mean of 5.07 to 2.32 at 2 weeks, 2.00 at 1 month, and 1.35 at 3 months (χ² = 60.63, p < 0.0001). This represents a 73.4% reduction in pain scores from baseline to 3 months. McGill Pain Questionnaire scores similarly decreased from 10.50 at baseline to 5.00 at 2 weeks, 4.00 at 1 month, and 3.00 at 3 months (χ² = 57.31, p < 0.0001), a 71.4% reduction.

Post-hoc analyses with Bonferroni correction confirmed significant improvements at all time points compared to baseline (p < 0.05).

Functional improvement was also significant. ODI scores decreased from 24.52 at baseline to 14.48 at 2 weeks, 13.76 at 1 month, and 12.00 at 3 months (χ² = 55.66, p < 0.0001), representing a 51.1% reduction in disability. The ODI improvement at 3 months was also significantly better than at 2 weeks (p < 0.05).

Effect sizes were large to very large across all measures. Cohen's d values for VAS were 1.61 (baseline to 2 weeks), 1.80 (baseline to 1 month), and 2.43 (baseline to 3 months). For McGill scores, Cohen's d was 1.42, 1.68, and 2.05. For ODI, Cohen's d was 1.06, 1.19, and 1.43.

The rank-biserial correlation exceeded 0.79 for all outcomes, and standardized response mean indicated significant clinical improvement, especially for VAS and McGill scores.

This study provides promising evidence that ultrasound-guided myofascial hydrodissection with saline is a safe and effective treatment for myofascial pain syndrome. The large effect sizes and sustained improvements over three months suggest meaningful clinical benefits for patients with chronic MPS. The absence of adverse events adds to its appeal as a low-risk intervention.

For clinicians, UMHT offers several potential advantages over existing treatments. Unlike dry needling, which primarily addresses the neuromuscular component of trigger points, UMHT combines trigger point inactivation with hydrodissection of surrounding fascial tissues, potentially providing more comprehensive and longer-lasting benefits. Compared to trigger point injections with medications like lidocaine or botulinum toxin, UMHT uses only saline, avoiding drug-related side effects and reducing costs. The ultrasound guidance improves precision and may be particularly valuable for deeper anatomical structures that are difficult to target with conventional approaches.

However, important caveats exist. This was a retrospective study without a control group, so the observed improvements cannot be definitively attributed to UMHT alone—placebo effects, natural history, and concurrent treatments may have contributed. The small sample size of 28 patients from a single center limits generalizability. The lack of objective diagnostic criteria for MPS and the absence of long-term follow-up beyond 3 months are additional limitations.

The authors appropriately note that randomized controlled trials comparing UMHT to standard treatments like dry needling, physiotherapy, or sham procedures are needed to establish its relative efficacy and rule out placebo effects.

For patients with chronic myofascial pain that has not responded to conservative treatments, UMHT may represent a minimally invasive option worth discussing with their healthcare provider, particularly if they are seeking to avoid medications or more invasive procedures.