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The Effect of Low-Level Laser in Knee Osteoarthritis: A Double-Blind, Randomized, Placebo-Controlled Trial
Béla Hegedűs, László Viharos, Mihály Gervain, Márta Gálfi. Photomedicine and Laser Surgery. August 2009, 27(4): 577-584. doi:10.1089/pho.2008.2297.
Published in Volume: 27 Issue 4: August 20, 2009 Online Ahead of Print: June 16, 2009

Introduction: Low-level laser therapy (LLLT) is thought to have an analgesic effect as well as a biomodulatory effect on microcirculation. This study was designed to examine the pain-relieving effect of LLLT and possible microcirculatory changes measured by thermography in patients with knee osteoarthritis (KOA).
Materials and Methods: Patients with mild or moderate KOA were randomized to receive either LLLT or placebo LLLT. Treatments were delivered twice a week over a period of 4wk with a diode laser (wavelength 830nm, continuous wave, power 50mW) in skin contact at a dose of 6J/point. The placebo control group was treated with an ineffective probe (power 0.5mW) of the same appearance. Before examinations and immediately, 2wk, and 2 mo after completing the therapy, thermography was performed (bilateral comparative thermograph by AGA infrared camera); joint flexion, circumference, and pressure sensitivity were measured; and the visual analogue scale was recorded.
Results: In the group treated with active LLLT, a significant improvement was found in pain (before treatment [BT]: 5.75; 2 mo after treatment : 1.18); circumference (BT: 40.45; AT: 39.86); pressure sensitivity (BT: 2.33; AT: 0.77); and flexion (BT: 105.83; AT: 122.94). In the placebo group, changes in joint flexion and pain were not significant. Thermographic measurements showed at least a 0.5°C increase in temperature—and thus an improvement in circulation compared to the initial values. In the placebo group, these changes did not occur.
Conclusion: Our results show that LLLT reduces pain in KOA and improves microcirculation in the irradiated area.

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