Teixeira AM et al. - Photobiomodulation combined with a magnetic field for neck and shoulder pain

In 72 adults with chronic nonspecific neck or shoulder pain, photobiomodulation combined with a static magnetic field reduced pain intensity compared with a placebo in the short term. However, no differences were observed in joint range of motion or treatment satisfaction.

What this study measured

This is a single randomized controlled trial, conducted as a triple-blind study (blinded to patients, therapists, and evaluators), and not a meta-analysis. Seventy-two patients with chronic nonspecific neck and/or shoulder pain were divided into two groups of 36: photobiomodulation combined with a static magnetic field in active mode, or an identical-looking placebo device.

The treatment was administered twice a week for three weeks. The primary outcome measure was pain intensity, measured 15 minutes after the last session, then at 24, 48, and 72 hours, and at 7 days. Secondary outcome measures included joint range of motion, patient-reported satisfaction, and adverse effects.

Key Findings

The summary reports mixed results depending on the criterion considered: favorable results regarding pain and neutral results regarding the other aspects.

• 72 randomized patients, 36 in the active group and 36 in the placebo group
• Schedule: 2 sessions per week for 3 weeks
• Intensité de la douleur réduite dans le groupe actif à tous les temps de mesure par rapport au placebo (p < 0,05)
• There was no difference between the groups in terms of joint range of motion or satisfaction (p > 0.05)
• Pain relief described by the authors as short-term

The summary does not provide a confidence interval, a quantified effect size, or details on the adverse effects reported. Nor does the summary include specific light dose parameters.

How photobiomodulation works for this indication

The proposed mechanisms remain hypothetical. Red and near-infrared light is thought to be absorbed by cytochrome c oxidase, a photon acceptor in the mitochondrial respiratory chain; this absorption could increase ATP production and alter cellular signaling. Modulation of the local inflammatory response and tissue perfusion has also been suggested as a possible explanation for an analgesic effect. These hypotheses are based on experimental studies and are not demonstrated by this trial, which did not measure any biological markers.

Limits You Should Know

The main limitation stems from the intervention itself: it combines photobiomodulation and a static magnetic field in a single device. The observed effect therefore cannot be attributed solely to photobiomodulation, since none of the trial arms allow for the separation of these two components.

The negative results are worth reiterating: neither joint range of motion nor patient satisfaction differed from the placebo group. The sample size remains small, and follow-up ended 7 days after the last session, which provides no information on the durability of the benefit. This is a single trial, conducted on patients with so-called nonspecific chronic pain, whose results call for independent replication. Finally, the authors’ affiliations include a manufacturer of phototherapy devices, a factor to keep in mind.

What This Means in Practice

These data suggest that a combined treatment protocol may provide short-term pain relief in cases of chronic nonspecific neck or shoulder pain. They do not support recommending photobiomodulation alone, nor do they suggest that an improvement in mobility can be expected. Persistent neck or shoulder pain warrants a medical evaluation to rule out a specific cause before considering any complementary approach.

Frequently Asked Questions

Would photobiomodulation alone have produced the same result?

The study does not provide an answer. The device tested combined light and a static magnetic field in a single unit, and there was no control group that compared light alone. Attributing the benefit solely to photobiomodulation would be an extrapolation that these data do not support.

How long does the observed effect last?

The longest follow-up period reported is 7 days after the last session. During this period, the difference compared with the placebo is maintained at each measurement. Beyond that, the trial provides no information, and the authors themselves refer to a short-term effect.

Did the treatment improve neck and shoulder mobility?

No. Joint range of motion was one of the secondary endpoints, and no significant difference was observed between the active group and the placebo group. Reported satisfaction with the treatment also did not differ between the two groups.

Reference

Teixeira AM, Leal-Junior ECP, Casalechi HL, Vanin AA, de Paiva PRV, Melo FHC, Johnson DS, Tomazoni SS. Photobiomodulation Therapy Combined with a Static Magnetic Field Reduces Pain in Patients with Chronic Nonspecific Neck and/or Shoulder Pain: A Randomized, Triple-Blinded, Placebo-Controlled Trial. Life (Basel), 2022. PMID 35629324. DOI 10.3390/life12050656. https://doi.org/10.3390/life12050656

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.