High-intensity versus low-level laser therapy in treatment of patients with subacromial impingement syndrome: a randomized, double-blind, controlled trial.

To compare the effects of High-Intensity Laser Therapy (HILT) versus Low-Level Laser Therapy (LLLT) on shoulder pain and disability, shoulder Range of Motion (ROM), Pain Pressure Threshold (PPT), and sleep quality of patients having Subacromial Impingement Syndrome (SAIS). Forty-two patients with SAIS were randomly assigned into three groups, the HILT group (n = 14), the LLLT group (n = 14), and control group (n = 14). All groups received an exercise program consisted of shoulder muscles stretching and strengthening exercises. Along with the exercise program, the HILT group received HILT at 810 nm /980 nm, and LLLT group received LLLT at 904 nm, three times weekly for three weeks. The primary outcome was the change in shoulder pain and disability measured by Shoulder Pain and Disability Index (SPADI). Secondary outcomes included shoulder ROM using a standard goniometer, PPT measured by pressure algometer, and sleep quality by Pittsburgh Sleep Quality Index (PSQI). Measurements were taken both before and after a 3-week intervention to assess the outcomes. After 3-wk intervention, both the HILT and LLLT groups exhibited significant improvements in all parameters when compared to the control group (p < 0.05). Additionally, there were clinically significant differences between groups supported by a large ES favoring the HILT group for SPADI pain (ηp² = 0.71), SPADI disability (ηp² = 0.54), SPADI total (ηp² = 0.82), PPT (ηp² = 0.63), and PSQI (ηp² = 0.42). The combination of HILT with exercises proved to be more beneficial in enhancing pain and function, PPT, and sleep quality compared to LLLT combined with exercises in treating patients with SAIS.