May 10th, 2024
Red Light Therapy and Musculoskeletal Health
Almost everyone has heard of red light therapy at least once in the past few years. Social media is stuffed with posts about its pros and cons. Celebrities have been known to demand red light before they walk the red carpet. So, what’s it all about?
For the past 50 years, scientists have investigated the effects of red light and near-infrared radiation on the body. This therapy, now called photobiomodulation (PBM), has been shown to penetrate tissue to affect growth factor production, inflammation, chemical changes in cells, and cell-to-cell communication. PBM works by stimulating some processes and inhibiting others.
PBM is also known as:
- Red light therapy
- Low-level laser therapy
- Low-power laser therapy
- Cold laser therapy
- Soft laser therapy
- Biostimulation
Outside of the medical community, PBM is most often associated with treating skin-related problems such as acne, wrinkles, and psoriasis. The medical community, has researched the effects of PBM on everything from allergies to Alzheimer’s disease, heart failure to hearing loss, and spinal cord injury to stroke.[1] Over the past several years, the focus of PBM research has shifted to bone and muscle conditions.
Discovery of Red Light Therapy/PBM
In 1967, Endre Mester stumbled upon low-level laser therapy while working at the Semmelweis Medical University in Hungary.[2] He attempted to recreate a previous experiment to reduce tumor growth in rats, but he used a less powerful laser strength than the original study. Unfortunately, Mester was unable to cure any tumors during his research. However, he noticed that the rats he was using had increased hair regrowth, and improved inflammation and wound healing.
The American Society for Laser Medicine and Surgery (ASLMS) was founded in 1981. The ASLMS and multiple other groups continue to study PBM. Since 2001, over 2000 scientific articles have been written examining the different body systems that can be affected by PBM.[3]
Since Mester’s discovery, low-level laser therapy has been used to treat pain and inflammation in wound healing. Studies have found that a coherent (one type of wavelength) monochromatic (one color) laser is not the only option for achieving these results. Non-coherent (various types of wavelengths) light-emitting diodes (LED) with the same parameters will also work. This finding has led to commercially available LED therapies that can be used at home.
How Does Photobiomodulation Work?
Most commonly, PBM uses a low-level laser with power less than 500 mW, and red light or near-infrared light because it does not produce heat. The laser is directed to the treated area, but does not disturb the tissue above it. The photons given off by the laser are absorbed by the target tissue and activate the mitochondria (powerhouse of the cell). As the mitochondria are activated, they produce adenosine triphosphate (ATP), which provides energy for many processes within the cell. The photons also reduce oxidative stress and trigger several transcription factors. All these processes lead to decreased pain and inflammation, and better tissue repair.[4]
The Good: Indications for PBM in Orthopedic Settings
Multiple studies have shown PBM’s positive effects on pain and inflammation.[5] These effects make PBM helpful in treating acute and chronic pain. These studies show decreased use of pain-relieving medications in patients treated with PBM. Most importantly, PBM has no side effects when used correctly.
Specific Indications for PBM:
- Osteoarthritis: significant improvement in pain, function, and quality of life[5]
- Total hip arthroplasty: improved post-surgical pain management
- Non-specific knee pain: better physical function and decreased pain
- Temporomandibular disorders: reduced pain
- Fibromyalgia: decreased pain when combined with exercise
- Neck pain: decreased pain
- Carpal tunnel syndrome: decreased symptom score and increased functional score[7]
- Lower back pain: some findings of reduced pain, more research is needed
- Bone fractures: accelerated bone regeneration in animal studies[8]
The Bad: A Problem With Consistency
The term “low-level” is not specific and means different strengths to different people. Researchers using PBM choose a particular power range during their study, and their results are tied to those levels. If someone outside the study uses a different range, the results could be altered and may show less benefit.[6]
Many studies on PBM are done “in vitro,” which the Merriam-Webster dictionary defines as cells in a laboratory in a dish or test tube. Then, studies may move on to “in vivo” studies on living organisms, such as mice or rats.[9] The results from these studies may not apply to humans. Some studies done on human subjects have conflicting results. More research is needed to either confirm or disprove past studies and to provide more complete and reliable information on the use of PBM in humans.
The Ugly: Overrun with Gimmicks
A physician or other trained clinician provides orthopedic PBM in a controlled clinical environment. However, multiple commercially available products are offered by the skincare industry and other companies that anyone can use at home. These products may not be what they claim to be.
The FDA may “clear” a commercial PBM device. A Class III clearance means that a high-risk device, such as a heart valve, has passed a pre-market application by the FDA. A Class II clearance means the device has not been shown to cause harm compared to other devices in the same class.
Being cleared by the FDA does not mean the device has been proven to do what it says it will do. The FDA does not “approve” medical devices. If that word is used in an ad for a commercially available PBM device, that is false advertising.[10]
A quick search of a large online retailer using “red light therapy,” yielded over 2,000 results. Devices ranged in price from $7.99 to $4,599. Although primarily targeted for skin care concerns, some devices are also marketed for pain, depression, and weight loss. Most of these devices have yet to be evaluated by the FDA.
These commercially available PBM devices likely cannot penetrate the tissue level needed to treat orthopedic conditions. Before you purchase a device, discuss it with your doctor.
Conclusion
For over 50 years, photobiomodulation has been shown to help improve pain, reduce inflammation, and improve healing. However, not all research is consistent, and some studies show that PBM doesn’t work for various reasons. As research continues, better treatment options should become available. Currently, clinical use of PBM appears to be the most effective and safe option. If you think you might benefit from PBM, you should talk to your doctor.
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