Efficacy of low-level laser therapy associated to exercises in knee osteoarthritis: a randomized, double-blind study

INTRODUCTION: Osteoarthritis (OA) is a degenerative disease that affects synovial joints, one of the most common causes of functional limitation. OBJECTIVES: To estimate the effects of Low-Level Laser Therapy (LLLT), in combination with a program of exercises on pain, range of motion, muscular strength, functionality, mobility and quality of life in patients with osteoarthritis of the knee. METHODS: Sample consisted of 40 participants of both genders, ages ranging from 50 to 75 years. All had level 2-4 OA. Participants were randomized into two groups: Laser Group (low-level laser, 3 Joules dose and exercises), and Placebo Group (placebo-laser and exercises). Pain was assessed using visual analogical scale (VAS), range of motion with the universal goniometer, muscular strength using a dynamometer, functionality using the Lequesne Questionnaire, mobility using Timed Get Up and Go (TGUG) and quality using the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) of life in five moments: (T1) baseline, (T2) after at the end of laser therapy (3rd week), (T3) after the end of exercises (11th week), (T4) three and six months after the treatment (T4 and T5). The intervention was performed during three weeks; patients received laser therapy or placebo three times a week; for the remaining 8 weeks, all patients exercised three times a week. Data was assessed through Friedman and Mann-Whitney non-parametrical tests, with 5% significance. RESULTS: In the intragroup analysis, the Laser Group showed significant improvement in pain (p<0.001), range of motion (p=0.032), functionality (p=0.003), mobility (p<0.001), WOM-pain (p=0.001), WOM-function (p<0.001) and WOM-total (p<0.001), while the Placebo Group showed a significant difference in mobility (p=0.013), WOM-function (p=0.017) and WOM-total (p=0.02). In the analysis between groups there was significant difference in AV2 between groups for variables WOM-function (p=0.01) and WOM-total (p=0.02) and in AV3 for variables WOM-pain (p<0.01), WOM-function (p=0.01) and WOM-total (p=0.02), indicating an improvement in the Laser Group. There was also observed a greater relative gain in almost all variables throughout the evaluations, when compared to the Placebo Group. CONCLUSION: The Low Level Laser Therapy combined with an exercise program is effective in improving pain, function, range of motion and quality of life of patients with knee osteoarthritis.