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Tomasz Poboży

High-Intensity Laser Therapy for Knee Osteoarthritis — Large Effect, Important Caveats

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Tomasz Poboży

The trial is striking because of the size of the WOMAC difference, but it does not yet establish high-intensity laser therapy as standard treatment for knee osteoarthritis. The comparison was with therapeutic ultrasound, not with a sham procedure or exercise alone, which substantially limits what can be concluded.

Why is this study interesting?

Physical modalities are often added to exercise programmes for knee osteoarthritis even though the benefit of individual techniques remains uncertain. A randomised trial from Thailand, published on 8 September 2026, compared high-intensity laser therapy (HILT) with therapeutic ultrasound. The reported between-group difference was much larger than the authors’ prespecified estimate of a minimally important change, making the result clinically interesting—but also worth examining carefully in light of the study design.

Question and methods

The single-centre trial enrolled 66 adults with knee osteoarthritis. Participants were randomised 1:1 to HILT or therapeutic ultrasound. Both modalities were delivered as an adjunct to exercise twice weekly for six weeks. The outcome assessor was blinded to treatment allocation.

The primary endpoint was change in the total WOMAC score 12 weeks after completion of treatment. The authors used 10 points as an approximate threshold for a minimally important change. Analysis followed the intention-to-treat principle. The trial was registered retrospectively, after recruitment had begun.

Results

Mean improvement in WOMAC was 40.0 points in the HILT group and 8.2 points in the therapeutic-ultrasound group. The adjusted between-group difference was −27.7 points (95% CI −39.0 to −16.5; p<0.001). Secondary analyses also favoured HILT for pain, function and quality of life, with the reported effect persisting up to 12 weeks after treatment ended.

Clinical interpretation for an orthopaedic surgeon

The magnitude of the difference is difficult to ignore, but the trial answers a narrower question than the headline might suggest: HILT plus exercise performed better than therapeutic ultrasound plus exercise. It does not show how much of the observed difference was due specifically to the laser, and how much may have reflected differences in expectations, treatment experience or a relatively weak response in the comparison group.

It is also important that WOMAC and several other key outcomes were patient-reported. Blinding the outcome assessor does not remove the risk introduced when participants and therapists are likely to recognise which physical modality is being delivered.

Limitations

  • small, single-centre sample;
  • short follow-up;
  • no sham-treatment group and no exercise-only group;
  • retrospective trial registration;
  • the minimally important change threshold was used as an approximation rather than a value validated specifically for this population and comparison;
  • secondary outcomes were exploratory;
  • a large effect from one centre requires independent replication.

What could this change in practice—and what does it not prove?

The study provides a credible preliminary signal that HILT may be a useful adjunct to exercise for some patients with knee osteoarthritis. It justifies a larger trial with sham treatment, longer follow-up and an economic evaluation. It does not prove superiority over exercise alone, a disease-modifying effect, or that routine funding of HILT is justified. It also does not identify which patients, if any, are most likely to benefit.

Source

Ninlerd C, Benjakulsap N, Amornsupak C, et al. Efficacy of high-intensity laser therapy versus ultrasound therapy in patients with knee osteoarthritis: a randomized controlled trial. Lasers Med Sci. 2026;41(1):219. DOI: 10.1007/s10103-026-05019-8. PubMed.

Polish version · For Doctors and Physiotherapists

Content prepared by: Tomasz Poboży - orthopaedic surgeon.

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