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 830 nm, continuous wave, power 50mW) in skin contact at a dose of 6 J/point.
The placebo control group was treated with an ineffective probe (power 0.5mW) of the
same appearance. Before examinations and immediately, 2 wk, 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 degrees 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.
