Low-Level Light Therapy for Osteoarthritis – How Does it Work, if at all?

by LMatthews on May 1, 2014

lllt for back painAt least half of us will experience osteoarthritis during our lives, and some 80% of those over 75 have this condition. Caused by wear and tear, injury and trauma to the joints, and other factors, osteoarthritis can be a cause of spinal stenosis and back pain.

Many people resort to long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) to cope with their back pain from osteoarthritis but an alternative approach, low-level light (laser) therapy (LLLT) is becoming increasingly popular.

Conventional Treatment Risks

NSAIDs and other systemic drugs such as COX2 inhibitors and acetaminophen are associated with a wide range of adverse effects, including gastrointestinal upset, bleeding and stomach ulcers and even an increased risk of heart attack in some cases. They may also precipitate degenerative changes in the bones by affecting bone mineralisation and remodelling, especially after back surgery or other surgery involving bone grafts. This means that people are looking for adjunct therapies that allow patients with osteoarthritis to reduce their dependency on NSAIDs and other potentially harmful drugs. LLLT is one such therapy.

Benefits of LLLT for Osteoarthritis

There are no known side effects of LLLT and evidence from animal research so far suggests significant therapeutic benefits. In a recent study, published in Arthritis Research & Therapy, Alves et al. found that a single use of LLLT significantly reduced levels of inlammatory cytokines and inflammatory cell infiltration 24 hours later. The rats used in this study were deliberately injured through the injection of the cartilage-degrading enzyme papain. The laser light frequency used was 808-nanometers, 4 Joules, and either 50-mW or 100mW. The rats were killed after 24 hours to assess their joints.


How LLLT Works

LLLT appears to help encourage healing of joint tissue while reducing pain and inflammation. It may also help prevent tissue death after injury, including ischaemic injury (where blood flow is obstructed resulting in tissue death). These benefits are thought to occur due to the absorption of red or near-infrared photons by cytochrome c oxidase, which leads to increased mitochondrial activity and increased production of adenosine triphosphate (ATP), the main energy molecule in the body.

More Benefits of LLLT for OA

LLLT also appears to initiate signalling pathways involving nitric oxide, cyclic AMP, and reactive oxygen species, altering blood vessel function, energy, protein synthesis and free radical damage to cells. Inflammatory cells such as neutrophils, macrophages, lymphocytes, and mast cells are inhibited by LLLT, as are interleukins and tumor necrosis factor-alpha, which are key factors in inflammatory joint disease. Increased angiogenesis (blood vessel growth) and decreased fibrosis (scar tissue formation) was also seen in earlier research into LLLT at a lower power.

Why Not Use a Higher Power

It is thought that the increase in cellular energy produced by LLLT is the reason why higher power lasers are less effective and even counterproductive to joint health. In the rat model, analysis of the animals’ joints after they were killed revealed a significant reduction in inflammatory cells in synovial fluid at both power levels but a bigger reduction in macrophages at the 50-mW power level.

Interleukin-1beta and interleukin-6 mRNA were more significantly reduced by 50mW, but TNF-a was reduced more by the higher power 100mW treatment. Longer applications at a lower power may be the reason behind the increased benefits of the 50mW therapy.

The research so far has concentrated on animal models, with the lab animals having injuries similar to osteoarthritis induced acutely before treatment and death. This means that the results may not be representative of the response in those with long-standing osteoarthritis, especially as rat metabolism and human metabolism can vary significantly, as has been seen with numerous drugs over the years.

As such, clinical trials using human volunteers are necessary in order to really reveal the benefits and risks of low-level laser therapy for osteoarthritis.

Reference

Michael R Hamblin, Can Osteoarthritis Be Treated With Light? Arthritis Res Ther. 2013;15(5)


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