Effect of photobiomodulation on trapezius myofascial pain: a randomized, sham-controlled, double-blind clinical trial.

Clinical Snapshot

Key Findings

• P Value: Pain: p=0.30; Trigger points: p=0.57; Cervical skin temperature: p=0.45; Trapezius temperature: p=0.34; Global perceived effect: p=0.17; Cervical function (LLLT group): p=0.04

• Effect Size: Pain: η² = 0.024 (trivial); Trigger points: η² = 0.007 (trivial); Cervical skin temperature: η² = 0.042 (small); Trapezius temperature: η² = 0.021 (trivial); Global perceived effect: η² = 0.029 (trivial); Cervical function (LLLT group significant): η² = 0.070 (small-to-moderate)

• Primary Outcome: Pain perception: No significant between-group difference [F(2,100) = 1.21; p = 0.30; η² = 0.024]. Both groups reported clinically relevant pain reduction within groups.

• Nnt Or Sensitivity: NNT not calculable from available data. No statistically significant between-group difference on primary outcome; the single significant finding (cervical function) was within the LLLT group only, without a reported between-group comparison effect size sufficient to calculate NNT.

• Confidence Interval: Not reported in the abstract for any outcome

Clinical Application

LLLT devices operating at 808 nm are commercially available in Australian physiotherapy and sports medicine practices. An 8-session protocol over 4 weeks is clinically feasible. However, given the absence of demonstrated superiority over sham for pain — the primary patient-presenting complaint — routine adoption of this specific protocol cannot be recommended on the basis of this trial alone. LLLT/photobiomodulation is not currently listed on the Medicare Benefits Schedule (MBS) as a standalone reimbursable intervention for myofascial pain in Australia, meaning patients typically bear out-of-pocket costs. The TGA regulates LLLT devices as Class IIa medical devices; 808 nm devices are commercially available. RACGP and APA (Australian Physiotherapy Association) guidelines for chronic musculoskeletal pain emphasise multimodal, exercise-based approaches as first-line management. This trial's null primary outcome does not support LLLT as a superior alternative to sham for pain relief in this population, and the modest cervical function benefit requires replication in larger, adequately powered trials before influencing Australian clinical practice guidelines. Adults with chronic trapezius myofascial pain and active trigger points presenting to physiotherapy, sports medicine, or musculoskeletal medicine clinics. The population is broadly representative of a common clinical presentation seen in primary care and allied health settings.

Abstract

To investigate the effect of 16 J of 808 nm low-level laser therapy (LLLT) on pain in individuals with trapezius trigger points (TPs). Randomized, double-blind, controlled trial conducted with 52 adults (≥ 18 years) with chronic trapezius pain and TPs. Participants were assigned to the LLLT group (808 nm, 16 J per TP) or the sham group (same protocol without emission). Both received eight sessions over four weeks. Outcomes included pain perception, number of TPs, cervical function, skin temperature, global perceived effect, and adverse events. Randomization was concealed from evaluators and participants. Repeated measures ANOVA (SPSS 21) was used for analysis. No significant differences were found between groups for pain [F(2,100) = 1.21; p = 0.30, η2 = 0.024], TPs [F(1.09,54.27) = 0.35; p = 0.57, η2 = 0.007], cervical skin temperature [F(1.79,89.65) = 0.79; p = 0.45, η2 = 0.042], trapezius temperature [F(2,100) = 1.09; p = 0.34, η2 = 0.021], or global perceived effect [F(1.44) = 1.91; p = 0.17, η2 = 0.029]. Cervical function improved significantly in the LLLT group [F(1.36,67.73) = 3.75; p = 0.04, η2 = 0.070]. Adverse effects were mild and infrequent, mainly warmth. Both groups reported clinically relevant pain reduction. LLLT at 16 J per TP with 808 nm was not superior to placebo for pain, TP count, or skin temperature. However, it improved cervical function, suggesting a functional benefit. Registration: july 18, 2022 on the Brazilian Clinical Trials Registry (REBEC - RBR-10m474jv).

References

1. 1.Silva, R. K. N., Rocha, A. M. M. F., Oliveira, V. M. A., Santos, J. N. M., Nascimento, J. D. S., & Andrade, P. R. (2026). Effect of photobiomodulation on trapezius myofascial pain: a randomized, sham-controlled, double-blind clinical trial. Lasers in Medical Science. https://doi.org/10.1002/mus.28377