What does medical literature report on low level laser therapy for knee pain?
In the United States Knee Pain is the second most common cause of chronic pain. One third of all Americans (nearly 100 million) experience knee pain at some time or another. Knee pain can result from a wide variety of causes, but generally fall into one of three categories. One category is injury which can include blunt trauma, positional trauma like sprains, cartilage and ligament tears from sports or recreational activities, or post-surgical situations. A second category consists of disease states such as arthritis (osteo, rheumatoid, psoriatic, lupus, plica syndrome, etc.). A third category consists of conditions which do not have a clear etiology such as Osgood-Schlatter disease). A common pain producing thread of these conditions is inflammation.
Gur A, et al. (2003), Efficacy of different therapy regimes of low-power laser in painful osteoarthritis of the knee: a double-blind and randomized-controlled trial, Lasers in Surgery and Medicine 33:330-38.
Bjordal JM, et al. (2006b), Low-level laser therapy in acute pain: a systematic review of possible mechanisms of action and clinical effects in randomized placebo-controlled trials, Photomed. Laser Surg. 24:158-68,
Pallotta RC, et al. (2012), Infrared (810-nm) low-level laser therapy on rat experimental knee inflammation, Laser Med. Sci. 27:71-8,
Balint G, et al. (2011), Expression of vimentin and a-enolase, potential ex vivo soft-laser treatment inhibits the synovial, J. Am. Phys. Ther. Ass. 91:665-74,
Gur et al. (2003) evaluated the efficacy of laser therapy (another form of LLLT) in a prospective, double-blind, randomized, and placebo-controlled study of 90 subjects with knee osteoarthritis. Subjects were randomly assigned to one of three treatment groups: (1) actual low-powered laser treatment for five minutes and exercise; (2) actual low-powered laser treatment for three minutes and exercise. or (3) placebo laser and exercise. All patients were evaluated based on pain, degree of active knee flexion (a measure of the ability of a patient to bend their knee), duration of morning stiffness, painless walking distance and duration, and the Western Ontario and Mc Master Universities Osteoarthritis Index (“WOMAC”) measure of pain. Follow-up measures were evaluated at baseline, four, eight, and twelve weeks after the last laser therapy. In both laser groups, statistically-significant improvements were detected in all outcome measures including pain level at movement, pain level at rest, pain level while flexing, and painless walking duration and distance in the post-therapy period when compared to pre-therapy (p < 0.01). Moreover, improvements of pain measures, including pain at movement, at rest, and at knee flexion in both actual laser groups during the trial period were statistically significant when compared to the placebo laser group (p < 0.05). Improvements in WOMAC scores in both of the actual laser groups were statistically significant compared to scores in the placebo group (p < 0.05). Finally, subjects treated with LLLT reported more than 50% pain relief four weeks after treatment
Bjordal et al. (2006b) conducted a review of animal and in vitro studies and found strong evidence that LLLT modulates biochemical inflammatory markers and produces local anti-inflammatory effects in cells and soft tissue. They found strong evidence from 18 out of 19 studies that red and infrared wavelengths of LLLT can act locally and rapidly to modulate the inflammatory processes in injured tissue. These anti-inflammatory effects include changes in biochemical markers, altered distribution of inflammatory cells, and reduced formation of edema, hemorrhage, and necrosis.
Pallotta et. al. (2012) evaluated the effects of LLLT on rat knee inflammation. The study demonstrated that LLLT likely acts to modulate inflammatory process and possibly stimulates the production of anti-inflammatory mediators. This would, therefore, be expected to reduce swelling
Balint et al. (2011) studied synovial tissue samples of five women who underwent total knee replacement surgery. Two samples per participant, one for LLLT treatment and one to serve as a control, were cut from two adjacent areas. LLLT irradiation was performed. Two important proteins, vimentin and α-enolase, have been implicated in citrullinated autoantigen-driven autoimmunity. Ultimately, the study indicates that LLLT favorably alters protein expression which play important roles in inflammatory symptoms of RA.
With inflammation being a common denominator in most instances of knee pain, the Gur, Bjordal, Pallotta, and Balint as well as numerous other studies provide competent and reliable scientific evidence that LLLT has a beneficial effect in those with knee pain.