Infrared light therapy (IRLT) is a non-invasive treatment that utilizes specific wavelengths of light to stimulate biological processes within the body. This approach, often categorized under photobiomodulation (PBM), involves applying light energy to tissue to encourage healing and reduce inflammation. As an adjunct therapy, IRLT presents a promising method to support the body’s natural recovery processes following a fracture.
Understanding Infrared Light
Infrared light is electromagnetic radiation that exists just beyond the visible red spectrum, making it invisible to the human eye. This spectrum is generally divided into near-infrared (NIR), mid-infrared, and far-infrared based on wavelength. The therapeutic application for deep tissue repair, such as in bone, primarily focuses on the NIR range, typically spanning from about 630 to 1000 nanometers.
The ability of NIR light to penetrate biological tissue is what makes it suitable for treating deep structures like bone. Unlike visible light, which is largely absorbed at the skin’s surface, NIR wavelengths can pass through the skin, fat, and muscle layers to reach the underlying fracture site. This deeper penetration ensures that the light energy is delivered directly to the cells involved in the repair process. The light energy must be absorbed by specific molecules within the cells, known as chromophores, to initiate a biological response.
The Cellular Mechanism of Bone Repair
The mechanism by which infrared light promotes bone healing begins at the cellular powerhouses called mitochondria. The primary cellular target, or chromophore, for NIR light is an enzyme within the mitochondria called cytochrome c oxidase. When a cell is stressed or injured, as happens in a fracture, this enzyme can be inhibited by nitric oxide (NO), which slows down the cell’s energy production.
The photons from the infrared light are absorbed by cytochrome c oxidase, causing the nitric oxide molecule to detach from the enzyme. This photodissociation allows oxygen to reattach to the enzyme, effectively restoring the electron transport chain and significantly increasing the production of Adenosine Triphosphate (ATP). This energy boost fuels the entire repair process.
The elevated ATP levels drive the necessary metabolic activities for osteogenesis, which is the formation of new bone. This energy stimulates the proliferation and differentiation of osteoblasts, the specialized cells responsible for synthesizing the new bone matrix. It promotes the activity of fibroblasts, which form the structural framework and fibrous callus required to bridge the fracture gap.
The light-induced release of nitric oxide causes local vasodilation, increasing blood flow to the injured site and delivering more oxygen and nutrients. Photobiomodulation modulates the inflammatory response, reducing pro-inflammatory markers and decreasing oxidative stress at the fracture site. By reducing inflammation and increasing cellular energy, IRLT creates a more favorable environment for bone tissue healing.
Application and Procedure for Fracture Treatment
Infrared light therapy is delivered to the fracture site using specialized devices, most commonly high-power light-emitting diodes (LEDs) or low-level lasers (LLLT). These devices are calibrated to emit light in the deep red to near-infrared spectrum, typically between 810 nm and 830 nm, to maximize tissue penetration and cellular absorption. The treatment is non-contact or involves light contact with the skin over the fracture area.
The treatment dosage is a specific variable, measured in Joules per square centimeter (\(\text{J/cm}^2\)), and must be carefully controlled to achieve a therapeutic effect. Delivering too little energy may have no effect, while delivering too much can be inhibitory to cellular activity.
Sessions are typically performed daily or several times per week, lasting between 10 and 15 minutes. The overall treatment duration spans several weeks, coinciding with the early and intermediate stages of fracture healing. Applying the therapy early enhances initial callus formation and may accelerate the progression to a solid bony union.
Safety Profile and Contraindications
Infrared light therapy is safe and non-thermal when used within the established therapeutic parameters. Because the light’s energy stimulates cellular processes rather than generating heat, the risk of tissue damage is minimal. Any sensation of warmth or temporary redness at the treatment site resolves quickly.
Despite its overall safety, there are specific situations where IRLT should be avoided, which are known as contraindications:
- The therapy should not be applied directly over known malignancies or cancerous growths due to concerns about stimulating cellular proliferation.
- Caution is advised near the thyroid gland, especially in cases of hyperthyroidism.
- Caution is advised over the abdomen of pregnant women.
- The treatment should be avoided over areas with active hemorrhage or impaired circulation.
- The treatment should be avoided in patients taking photosensitizing medications.
While metal implants are not an absolute contraindication, they may reflect the light energy, which can slightly affect the delivered dose, necessitating careful application. Consulting a healthcare provider is necessary to ensure the treatment is appropriate for a specific condition.