Abstract
Osteoarthritis (OA) is a chronic degenerative joint disease and is considered as the most common cause of pain and disability. To the best of our knowledge, it is generally observed that there is a lack of evidence on the effects of low-level laser therapy (LLLT) on inflammatory cytokines in OA. The present review aims to appraise the current evidence of efffects of LLLT on inflammatory cytokines in OA of the knee. Medical databases such as Medline, PubMed, EMBASE, PEDro CINAHL, Web of Science, Cochrane register, and Google reference were searched from its inception to June 2019. Articles that meet the inclusion criteria: subjects (animals-Wistar rats) induced with OA; rats with age group of 50-90 days; weight of 150-300 g; finding the effects of LLLT; reporting inflammatory cytokines; and articles written in English were included. The reviewers assessed the methodological quality of the primary studies. Data of inflammatory cytokines IL-1β, IL-6, TNF-α, and MMP-13 were extracted for analysis. The Q (x
) test and I
statistics analysis were performed to find the heterogeneity evaluation. Standard mean difference (SMD) and its 95% confidence interval (CI) were used to synthesize the data. Two hundred eleven potential articles were identified and 186 articles were excluded based on the selection criteria. The rest of the 25 articles were read and 8 articles were selected for further study. From the study, it is observed that the laser therapy group had mild to moderate improvement than control group in IL-1β, TNF-α, and MMP-13 (IL-1β; SMD 1.21 [95% CI - 0.278, 2.704], TNF-α; SMD 5.19 [95% CI 2.413, 7.961], and MMP-13 SMD - 1.45 [95% CI - 5.121, 2.211]), while IL-6 [SMD 3.11 (95% CI 0.662, 5.549] did not show any considerable improvement after laser therapy. The present review provides the evidence of LLLT-dependent reduction of IL-1β, TNF-α, and MMP-13, and its ability to modulate proliferation of inflammatory cells, which makes LLLT a suitable treatment for OA. Though the included studies showed a high heterogeneity in treatment parameter, the beneficial effect of LLLT on changes in inflammatory cytokines, such as IL-6, seems to be unaffected.