Dry Needling in Subjects with Muscular Trigger Points in the Lower Quarter: A Systematic Review

This systematic review analyzed the efficacy of dry needling in the treatment of muscular trigger points in the lower quarter of the body (lumbar region, hip, and lower extremities). Trigger points are highly sensitive areas in taut muscle bands that cause local pain and may radiate to other regions. Epidemiological studies show that these points are the main source of pain in 30-85% of patients in pain clinics. The researchers performed systematic searches in six scientific databases, including PubMed, Cochrane Library, and others, initially identifying 2,232 potential studies.

After rigorous application of inclusion criteria, only six randomized controlled trials were selected for analysis, involving a total of 275 participants. The methodological quality was assessed using the PEDro scale, considered the gold standard for clinical trial evaluation. Four studies were classified as high quality (PEDro score ≥7) and two as adequate quality (score 5-6). The studies used two main dry needling techniques: the superficial technique, with needle insertion at 3-4 mm depth, and the multiple insertion technique, in which needles are repeatedly inserted and withdrawn at different points within the trigger point to elicit a local twitch response.

The results were consistent in demonstrating significant efficacy of dry needling for short-term pain reduction. All six studies reported statistically significant improvements in pain intensity measured by the Visual Analog Scale (VAS). An important finding was that the deep technique (multiple insertion) was superior to the superficial technique for pain relief, suggesting that needle depth influences therapeutic outcomes. However, the functional benefits were limited.

Only one study demonstrated significant short-term functional improvement, and none showed functional benefits maintained at long-term follow-up. In addition, no significant improvements were found in quality of life, depression, range of motion, or muscle strength. The clinical implications are important but limited. Dry needling emerges as a promising intervention for acute pain related to trigger points in the lower quarter, being described as cost-effective, low-risk, minimally invasive, and relatively easy to learn through adequate training.

The proposed mechanisms include mechanical disruption of dysfunctional motor endplates, changes in muscle tension, increased local blood flow, release of endogenous endorphins, and pain modulation through gate control theory. The review identified several important limitations. The limited number of available studies (only six) indicates a scarcity of robust scientific evidence in this area. Sample sizes were small (17-84 participants), limiting the generalizability of the results.

There were methodological inconsistencies among the studies, including different study populations, varied needling techniques, and heterogeneous outcome measures. The impossibility of blinding therapists due to the nature of the intervention may have introduced bias. In addition, most studies did not report minimum clinically important differences, focusing only on statistical significance. Follow-up limitations are also relevant, with only one study investigating effects beyond six months, and no study analyzing long-term effects beyond this period.

The lack of studies comparing dry needling with other physical therapy interventions or investigating treatment combinations limits clinical recommendations. The authors conclude that, although dry needling demonstrates efficacy for short-term pain reduction in lower-quarter trigger points, more high-quality studies with larger samples, long-term follow-up, and comparisons with other interventions are needed to establish its optimal role in the treatment of musculoskeletal conditions related to trigger points.