Low-level laser therapy has been used clinically to treat musculoskeletal pain; however, there is limited evidence available to support its use. The current Cochrance review fails to be positive: there are insufficient data to draw firm conclusions on the clinical effect of LLLT for low‐back pain. So, perhaps studies on animals generate clearer answers?
The objective of this study was to evaluate the clinical effectiveness of low-level laser therapy and chiropractic care in treating thoracolumbar pain in competitive western performance horses. The subjects included 61 Quarter Horses actively involved in national western performance competitions judged to have back pain. A randomized, clinical trial was conducted by assigning affected horses to either:
- laser therapy,
- or combined laser and chiropractic treatment groups.
Low-level laser therapy was applied topically to local sites of back pain. The laser probe contained four 810-nm laser diodes spaced 15-mm apart in a square array that produced a total optical output power of 3 watts. Chiropractic treatment was applied to areas of pain and stiffness within the thoracolumbar and sacral regions. A single application of a high velocity, low-amplitude (HVLA) manual thrust was applied to affected vertebral segments using a reinforced hypothenar contact and a body-centered, body-drop technique. The HVLA thrusts were directed dorsolateral to ventromedial (at a 45° angle to the horizontal plane) with a segmental contact near the spinous process with the goal of increasing extension and lateral bending within the adjacent vertebral segments. If horses did not tolerate the applied chiropractic treatment, then truncal stretching, spinal mobilization, and the use of a springloaded, mechanical-force instrument were used as more conservative forms of manual therapy in these acute back pain patients.
Outcome parameters included a visual analog scale (VAS) of perceived back pain and dysfunction and detailed spinal examinations evaluating pain, muscle tone, and stiffness. Mechanical nociceptive thresholds were measured along the dorsal trunk and values were compared before and after treatment. Repeated measures with post-hoc analysis were used to assess treatment group differences.
Low-level laser therapy, as applied in this study, produced significant reductions in back pain, epaxial muscle hypertonicity, and trunk stiffness. Combined laser therapy and chiropractic care produced similar reductions, with additional significant decreases in the severity of epaxial muscle hypertonicity and trunk stiffness. Chiropractic treatment by itself did not produce any significant changes in back pain, muscle hypertonicity, or trunk stiffness; however, there were improvements in trunk and pelvic flexion reflexes.
The authors concluded that the combination of laser therapy and chiropractic care seemed to provide additive effects in treating back pain and trunk stiffness that were not present with chiropractic treatment alone. The results of this study support the concept that a multimodal approach of laser therapy and chiropractic care is beneficial in treating back pain in horses involved in active competition.
Let me play the devil’s advocate and offer a different conclusion:
These results show that horses are not that different from humans when it comes to responding to treatments. One placebo has a small effect; two placebos generate a little more effects.