The Effect of Low Level Laser Therapy on Pain and Range of Motion of Patients With Knee Osteoarthritis

Purpose: Osteoarthritis is one the most common chronic diseases of the joints that mostly affects knee joint. Low power laser is one the minimally invasive treatments of osteoarthritis. However, the efficacy of this therapy is still controversial. This study aimed to evaluate the efficacy of low power laser therapy in reducing pain and increasing knee range of motion compared to placebo laser. Methods: This study was a double-blind clinical trial performed at a day clinic in Tehran, Iran, from March 2016 to February 2017. Treatment for both groups comprised 10 sessions, 5 times a week. In this study, low power laser with a wavelength of 810 nm and a power of 100 mW at 8 points was applied around the knee during two weeks of treatment. At the same time, laser was applied in the placebo group, but the power output was zero. Data analyses were performed by repeated measures ANOVA test using SPSS version 20. Results: The mean pain score at rest (P=0.691), as well as at activity (P=0.751) were not significantly different between the two groups. The range of motion of knee flexion (P=0.435), and the range of motion of knee extension (P=0.885) showed no significant difference between two groups. Both interventions over time lead to a significant change in pain at rest and at activity and also increase in the range of motion in knee flexion and extension (P 0.05). Conclusion: Both placebo treatment with routine physiotherapy and active laser therapy with routine physiotherapy decreased knee pain and increased knee range of motion in patients affected with osteoarthritis and there was no significant difference between two therapies.