Abstract

Low level laser therapy (LLLT) is a promising tool for rheumatic diseases, and a systematic Cochrane review suggests that LLLT could be considered in rheumatoid arthritis management due to positive outcomes for pain and morning stiffness. The possible mechanisms behind LLLT are moving from myth to reality through an increasing number of controlled LLLT trials. A literature search revealed 82 laboratory trials and 11 randomized controlled clinical trials reporting about LLLT effects in inflammatory processes and impaired metabolism of ligament, tendons and muscle. 71 laboratory trials provided positive outcomes for one or more parameters, and 7 clinical trials yielded positive results for reduction PGE2 levels, reduction of edema inflammatory cell infiltration and reduction of ESR levels. In 4 head-to-head comparisons with non-steroidal anti-inflammatory drugs (NSAIDs), there were no significant difference between NSAIDs and LLLT. The observed LLLT effects occurred locally and distinct dose-response patterns and therapeutic windows were found for anti-inflammatory effects (1 to 12 Joules), fibroblast stimulation (0.2 to 4 Joules) and fibroblast inhibition (above 6 Joules). A possible systemic effect cannot be ruled out, but with the application techniques and doses used in the published material, the effect size seem small and of doubtful clinical value. Bearing in mind, that the laboratory trials were performed mainly in rats and mice, clinical use of LLLT should take into account energy loss if depth from skin surface is larger than 2-3 mm and that most of the pathological organ needs to be irradiated. Given the dual possibility of reducing inflammation alongside with the promotion of tissue repair and the superior safety of LLLT over NSAIDs, LLLT can be adopted in the clinical management of rheumatic diseases.

Keywords: NSAIDs, arthritis model, Hemorrhage, wound repair, Endogenous Opioids