The efficacy of low-level laser therapy in supraspinatus tendinitis

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Abstract
Twenty-four subjects were randomly assigned to two groups to assess the effectiveness of low-power laser therapy for supraspinatus tendinitis. A low- power laser using a 820 nm, 40 mW probe operating at 5000 Hz to produce a dose of 30 J/cm2 was used to treat one group (L); the other group was treated with a similar, but dummy, laser (DL). The design of the trial was double-blind; patients, therapists and assessors being ignorant of the form of treatment used. The two groups each received a course of nine treatments and identical advice and educational material. Perceived pain was assessed and tenderness and secondary muscle weakness measured before and after the course of treatment. The data revealed that the L group had less pain (p < 0.05), less secondary weakness (p < 0.01) and tenderness (p < 0.05) after the treatment than before. No such changes occurred in the DL group; indeed, secondary weakness and tenderness increased slightly in the latter group after treatment. The degree of pain, tenderness and weakness of the two groups was similar before treatment. Comparing the two groups after treatment, L had less pain (p < 0.05) and less weakness (p < 0.001) than DL. These data suggest that, in this small group of patients, laser therapy, advice and education improved certain symptoms of supraspinatus tendinitis, while the same advice and education but treatment with a dummy laser had no such beneficial consequences. Based on the results, low-power laser therapy with the parameters and dosage used in this study is recommended as a useful treatment for tendinitis, but the trial was limited by small numbers.