Tripodi N et al. - Red and near-infrared photobiomodulation in tendinopathies

In tendinopathies, red and near-infrared photobiomodulation combined with exercise reduces pain more effectively than a sham treatment combined with exercise, according to a meta-analysis of 17 randomized trials. When compared on its own to other interventions, it is no more effective at reducing pain and results in a smaller improvement in function.

What this study measured

This is a systematic review with a meta-analysis of randomized controlled trials, not a single trial. The literature search was conducted in August 2020 across six databases. The included trials used red or near-infrared photobiomodulation to treat tendinopathy, with comparison to a sham treatment or another intervention. Data on pain and function were extracted and then synthesized using a random-effects model, with the mean difference (MD) and standardized mean difference (SMD) as measures. Seventeen trials involving a total of 835 participants were included. The protocol is registered under number CRD42020202508.

Key Findings

The values below are those published in the abstract, along with their 95% confidence intervals. The scales used are not specified there.

• Photobiomodulation alone versus other interventions, pain: SM = -0.09 (95% CI: -0.79 to 0.61), representing a comparable reduction
• Photobiomodulation alone versus other interventions, function: DMS = -0.52 (95% CI: -0.81 to -0.23), smaller functional improvement
• Photobiomodulation combined with exercise versus placebo treatment combined with exercise, pain: OR = 1.06 (95% CI: 0.57 to 1.55)
• Photobiomodulation combined with exercise versus sham treatment combined with exercise; function: DM = 5.65 (95% CI: 0.25 to 11.04)
• Photobiomodulation combined with exercise versus other exercise-based interventions, pain: OR = 0.31 (95% CI: -0.07 to 0.70), no difference
• Quality of evidence according to GRADE: very low to moderate, with most trials having a low risk of bias

How photobiomodulation works for this indication

The mechanisms described in the literature remain hypothetical and were not measured in this review. Red and near-infrared light are thought to be absorbed by cytochrome c oxidase, a presumed photoreceptor in the mitochondrial respiratory chain, which could increase ATP production within the exposed tendon tissue. A modulation of local inflammation and collagen matrix remodeling has also been proposed. Finally, an effect on pain pathways could contribute to the reported reduction in pain intensity. These explanations remain tentative.

Limits You Should Know

Negative results should be highlighted. When used alone compared with other interventions, photobiomodulation did not reduce pain any further, and the improvement in function was smaller. When combined with exercise, it did not perform better than other interventions also combined with exercise in terms of pain relief. The net benefit is therefore only evident when compared to a sham treatment. The quality of the evidence is rated as very low to moderate according to the GRADE system. The literature search ended in August 2020, which excludes trials published since then.

What This Means in Practice

The strongest message from this review is that photobiomodulation plays a supplementary role: it is being studied as an adjunct to an exercise program, which remains the standard of care for tendinopathies. It does not appear to be a substitute for other treatments. An evaluation by a healthcare professional is necessary to confirm the diagnosis and develop a progressive program.

Frequently Asked Questions

Does photobiomodulation eliminate the need for exercise?

No. The most significant benefits identified in this meta-analysis pertain to photobiomodulation added to an exercise program, compared to a sham treatment also added to exercise. Exercise remains the cornerstone of tendinopathy management. Photobiomodulation is evaluated here as a complementary treatment.

Red or near-infrared: Which one should you choose?

The review included studies using both red light and near-infrared light without distinguishing between the two. The abstract does not specify wavelengths, doses, or the number of sessions. Therefore, no preference can be inferred from it.

Do these results apply to all tendinopathies?

The abstract does not specify which tendon sites were included among the 17 trials. The results are grouped together, which obscures any possible differences between the Achilles tendon, the rotator cuff, and epicondylitis. Therefore, caution should be exercised before applying these figures to a specific situation.

Reference

Tripodi N, Feehan J, Husaric M, Sidiroglou F, Apostolopoulos V. The effect of low-level red and near-infrared photobiomodulation on pain and function in tendinopathy: a systematic review and meta-analysis of randomized controlled trials. BMC Sports Science, Medicine and Rehabilitation, 2021, 13(1):91. PMID 34391447. PMC8364035. DOI 10.1186/s13102-021-00306-z. https://doi.org/10.1186/s13102-021-00306-z

This summary is provided for informational purposes only and does not constitute medical advice. Photobiomodulation is not a substitute for prescribed treatment. Consult a healthcare professional.