Effectiveness of Low-Level and High-level Laser Therapy for Rotator Cuff-Related Shoulder Disorders: A Systematic Review and Meta-Analysis.

Introduction: While photobiomodulation and high-power lasers are common for rotator cuff-related shoulder pain, evidence interpretation is hindered by inconsistent dosimetry and clinical findings. This systematic review and meta-analysis evaluate the effects of low-level (LLLT) and high-level laser therapy (HLLT) on pain, range of motion (ROM), and shoulder function. Methods: This PROSPERO-registered review included randomized controlled trials comparing LLLT or HLLT against sham, no treatment, or conventional care. Two reviewers independently conducted screening, data extraction, and risk-of-bias assessment. Continuous outcomes were synthesized using random-effects models, supplemented by subgroup analyses (LLLT vs. HLLT; laser vs. laser plus exercise) and sensitivity analyses to address heterogeneity. Results: Twenty-three trials (wavelengths 805-1064 nm) were included. Pooled analysis showed that laser therapy significantly reduced overall pain (VAS: MD -5.22; 95% CI -7.56 to -2.88; P<0.001 P<0.001 P<0.001), though improvements in pain at rest, during movement, and at night were not statistically significant. After excluding outliers, modest improvements were noted in active internal rotation (MD 1.14; 95% CI 0.19-2.09; P<0.001 P<0.001 P<0.001) and passive external rotation (MD -1.33; 95% CI -1.92 to -0.73; P<0.001 P<0.001 P<0.001). Subgroup analysis indicated that HLLT yielded superior active-abduction outcomes compared to LLLT (P=0.016 P=0.016 P=0.016). Certainty was limited by heterogeneity, small sample sizes, inconsistent dosimetry, and short follow-up. Conclusion: Laser therapy provides modest, reproducible analgesic benefits, and selective ROM improvements, particularly when HLLT is combined with exercise. Given the limited functional gains and reporting inconsistencies, lasers should be used as an adjunct to structured rehabilitation rather than a standalone treatment. Future trials require standardized dosing and longer follow-ups.