Effectiveness of high-intensity laser therapy in the treatment of patients with frozen shoulder: a systematic review and meta-analysis

The purpose of this study is to evaluate the effects of high-intensity laser therapy (HILT) in patients with frozen shoulder. PRISMA guidelines were adhered to, and a systematic search was conducted in the PubMed, Web of Science, Scopus, CINAHL, Science Direct, and PEDro databases (last update: September 4, 2023; search period: December 2022–September 2023). The inclusion criteria encompassed RCTs comparing HILT with other physical therapy interventions in frozen patients with frozen shoulders, with or without sham HILT, assessing pain intensity, shoulder ROM, and disability outcomes. The quality of the RCTs was assessed with the Cochrane Risk of Bias tool, and evidence was assessed using the GRADE approach. Five trials met the eligibility criteria and were included in the review and meta-analysis, which pooled results from the visual analog scale (VAS), goniometry, and the shoulder pain and disability index (SPADI). Mean differences (MDs) for pain intensity and disability show a pooled effect in favor of HILT both for VAS (MD =  − 2.23 cm, 95% CI: − 3.25, − 1.22) and SPADI (MD =  − 10.1% (95% CI =  − 16.5, − 3.7), changes that are statistical (p < 0.01) and clinical. The MD for flexion (MD = 9.0°; 95% CI: − 2.36°, 20.3°; p = 0.12), abduction (MD = 3.4°; 95% CI: − 6.9°, 13.7°; p = 0.51), and external rotation (MD =  − 0.95°; 95% CI: − 5.36°, 3.5°; p = 0.67) does not show statistical and clinical differences between groups after treatment. PI and disability changes were graded as important due to their clinical and statistical results. HILT into a physical therapy plan reduce pain and disability, but it does not outperform conventional physical therapy in improving shoulder ROM. It is suggested that future RCTs compare the effects of HILT and LLLT to assess their possible differences in their analgesic effects.