Laser Acupuncture for the Pain of Knee Osteoarthritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Knee osteoarthritis is one of the most common and disabling conditions, affecting millions of people worldwide and causing deep pain and significant functional limitations in daily life. This chronic joint disease causes not only physical suffering but also considerable emotional and social impact on patients, as well as a high cost to healthcare systems globally. The characteristic pain of knee osteoarthritis is described as deep, throbbing discomfort that worsens with movement, weight-bearing activities, and prolonged standing. Conventional treatments include nonsteroidal anti-inflammatory drugs and corticosteroid knee injections, but growing interest in non-invasive and complementary therapies has drawn attention to laser acupuncture, a technique that combines traditional Chinese medicine principles with modern laser technology.

This study aimed to scientifically evaluate the efficacy of laser acupuncture for the relief of pain caused by knee osteoarthritis. The researchers conducted a systematic review and meta-analysis, a type of research that pools and analyzes data from multiple scientific studies to reach more robust conclusions. The methodology involved a comprehensive search of various international and Chinese medical databases, from the start of publication through September 2024, specifically looking for randomized controlled trials comparing laser acupuncture with other forms of treatment. The strict selection criteria included only studies with adult patients diagnosed with knee osteoarthritis, treatments lasting at least four weeks, and evaluation of outcomes important to patients, such as pain intensity, knee function, and adverse effects.

The methodologic quality of the studies was carefully assessed using standardized tools, and the certainty of evidence was rated according to the GRADE system, considered the international gold standard for evaluating the quality of scientific evidence.

The results of the analysis included five randomized controlled trials involving 293 patients with knee osteoarthritis, of whom 57% were women, with a mean age of approximately 63 years. All participants had moderate to severe knee osteoarthritis according to standard radiologic classification. The studies were conducted in different countries, including China, Australia, the United Kingdom, and Indonesia, ensuring geographic and cultural diversity in the sample. When laser acupuncture was compared with conventional physical exercise, the results showed a small reduction in pain intensity, equivalent to approximately 0.84 points on a 0-10 cm pain scale.

Although statistically significant, this difference may have limited clinical relevance for patients. On the other hand, when compared with placebo (sham treatment with an inactive laser), laser acupuncture demonstrated more substantial benefits, with a mean pain reduction of 2.33 points on the same scale, representing a clinically relevant improvement. In addition, patients receiving laser acupuncture had better knee function compared with the placebo group, with significant improvement in functional scores measured by the WOMAC scale, widely used to evaluate joint function.

The clinical implications of these findings are important for both patients and clinicians. For patients suffering from knee osteoarthritis, laser acupuncture emerges as a promising therapeutic option, especially for those who prefer non-invasive treatments or who have contraindications to conventional treatments. The technique offers distinct advantages over traditional needle acupuncture, including greater safety by eliminating risks associated with needle penetration, greater convenience with shorter sessions that may improve treatment adherence, and greater precision in the stimulation of acupuncture points. For clinicians, the results suggest that laser acupuncture may be cautiously considered as a complementary option in the management of pain from knee osteoarthritis, particularly when other therapies are not adequate or sufficient.

However, it is important to emphasize that, based on current evidence, laser acupuncture should be viewed as adjunctive treatment and not as a substitute for well-established first-line therapies.

This study has important limitations that must be considered when interpreting the results. The relatively small number of included studies (only five) and participants (293 total) limits generalization of the findings. The quality of evidence was rated as low according to the GRADE criteria, mainly due to methodologic problems in the original studies, including difficulties with adequate blinding of patients and therapists, and variability in treatment protocols. The moderate to high statistical heterogeneity among the studies suggests important differences in the methods and populations studied.

In addition, all included studies evaluated only short-term effects, with a maximum follow-up of a few months, making it impossible to draw conclusions about the long-term efficacy and safety of laser acupuncture. The absence of data on adverse effects in most studies also represents an important gap in the assessment of treatment safety. Considering these limitations, the researchers emphasize the urgent need for randomized controlled trials of higher methodologic quality, with larger samples and longer follow-up periods, to confirm these preliminary findings and establish more definitive clinical guidelines on the use of laser acupuncture in the treatment of knee osteoarthritis.