Low-Level Laser Therapy for Knee Pain – Meta Analysis

Did methodological flaws in earlier studies miss an effective pain therapy for knee osteoarthritis patients?

A team of researchers from Norway and Brazil think so and they took it upon themselves to conduct a review of randomized placebo-controlled studies to determine where laser therapy can, indeed, reduce arthritic knee pain and, importantly, if it can, then what’s the dose-response curve?

Their research, “Efficacy of low-level laser therapy on pain and disability in knee osteoarthritis: systematic review and meta-analysis of randomised placebo-controlled trials,” was published in the October 28, 2019 edition of BMJ Open.

Co-author Martin Stausholm, Ph.D. gave the background story of low-level lasers in osteoarthritic knee therapy to OTW, “Low-level laser therapy is known for its anti-inflammatory properties in knee osteoarthritis (KOA). Nevertheless, low-level laser therapy is not recommended in the major clinical guidelines for knee osteoarthritis management, and it is our impression that the modality is not widely recognized as an effective osteoarthritis intervention.”

“Our research group has published two randomized clinical trials indicating that low-level laser therapy with doses recommended by World Association for Laser Therapy can reduce pain in knee osteoarthritis.”

“The lack of recommendations for the use of low-level laser therapy in the guidelines might be a consequence of the conflicting conclusions of two recently published systematic reviews on the topic. We wondered whether the conflicting conclusions may have risen from a failed attempt to subgroup the trials in adherence to the World Association for Laser Therapy recommendations for low-level laser therapy dosing in one of the reviews and the lack of a dose-response relationship investigation in the other review.”

“Furthermore, we were aware of several relevant trials with low-level laser therapy positive results not included in the reviews. Thus, we decided to conduct a new systematic review with a correction for these methodological flaws.”

“Twenty-two trials were included in our review and meta-analysis. Initially, we found that pain and disability were overall significantly reduced by low-level laser therapy compared with placebo. Subsequently, we sub-grouped the trials according to the World Association for Laser Therapy recommendations for laser dose per treatment spot and this revealed a significant dose–response relationship.”

“The pain reduction from the recommended low-level laser therapy doses was significantly superior to placebo even at 12-week follow-up after the end of treatment, and the difference was greater than 20 mm on the 0-100 mm Visual Analogue Scale (VAS) from the final 4–8 weeks of treatment through follow-ups 6–8 weeks after the end of treatment.”

“These results are encouraging as they represent a clinically relevant improvement in knee osteoarthritis. Interestingly, the pain reduction from the recommended low-level laser therapy doses peaked at follow-ups 2–4 weeks after the end of therapy (31.87 mm VAS highly significantly beyond placebo).”

“Disability was also significantly reduced by the recommended low-level laser therapy doses compared with placebo, that is, to a moderate extent at the end of therapy and to a large extent during follow-ups 2–8 weeks later.

The non-recommended low-level laser therapy doses provided no or little positive effect, which underpins the importance of adhering to the dose recommendations. Importantly, the included trials were generally of high methodological quality and no adverse events were reported.”

“Low-level laser therapy reduces pain and disability in knee osteoarthritis at 4–8 Joules with 785–860 nm wavelength and at 1–3 Joules with 904 nm wavelength per treatment spot. We hope that orthopedic surgeons will advise knee osteoarthritis patients to try out low-level laser therapy as an adjunct to, e.g., exercise therapy before performing major knee surgery.”