• Wiegand R
• Marquina N
• Zhang J

• Association of Chiropractic Colleges / congresses

Objective: The objective of this study was to assess the effectiveness of low-level laser therapy in the treatment of chronic knee pain. The null hypothesis put forward in the study was that low-level laser therapy had no effect on osteoarthritis.

Materials and Methods: The study was approved by the institutional review board of a university. The research study consisted of a multi-site placebo controlled (double blind) randomized clinical trial. Subjects suffering from chronic knee pain were randomly assigned into control and experimental groups using a random table. Only the experimental group received active laser treatment. Sham laser was used in the control group. The primary outcome measure was based on the visual analog scale (VAS) score, expressed as the percent reduction in VAS score between the baseline value and the 30-day post treatment VAS score. The INSIGHT 50 laser (USA Laser, Virginia) was used as an adjunctive modality to standard treatment for knee pain using manipulative techniques. The manipulative treatment techniques were consistently applied as a baseline therapy to all participants regardless of their laser assignment into either experimental or control group. The laser probe consisted of a cluster of five, pulsed 910 nanometer near infrared laser diodes. The laser probe was capable of emitting laser energy in the near infrared with a maximum of 50 mW average power per diode. The multiple laser probe was used in direct contact with tissue in order to emit photons into the tissue according to a pre-programmed protocol.

Results: The 124 participants were randomly assigned to either of the “laser active” or “laser sham” group. Of these, 101/124 subjects completed the 30-day treatments. There were statistically significant differences between the Active and Sham Laser groups at Visit 12 and 30 day follow up. In addition, there were non-significant trends at baseline and treatment visits 1, 3, 6 and 9. For each of these results, the Active Laser groups mean VAS scores were lower than the Sham Laser group mean score.

Discussion:The resulting outcome measures obtained from the clinical trial demonstrates that the INSIGHT 50 laser provided significant relief and improvements in the primary evaluation criteria. The null hypothesis was rejected. This finding was consistent with other studies. The mechanism of the significant pain reduction was not clear. Based on recent study, it is possible that low-level laser therapy improves blood circulation, especially microcirculation. Laser was found to be effective in repairing damaged cartilages in joints and promote healing.

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