Abstract
Background: Laser irradiation is characterized by several physical parameters, such as wavelength, spot size, power, power density, energy, energy density, duration of irradiation, frequency of irradiation, and interval between irradiations. The lack of definitive evidence for the relevance of manipulation of these parameters to biological and clinical effects, combined with conflicting results from previous studies has led to uncertainties regarding the scientific rationale for the clinical application of laser technologies in physiotherapy.
Objective: The purpose of this review was to provide evidence of the scientific bases by examining the effects in humans and animals of two clinical applications of low-level laser technologies.
Methods: A systematic review was completed of original research papers investigating the effects in humans and common laboratory animals of laser acupuncture for pain relief and laser-stimulated wound healing. Relevant papers were primarily sourced from PubMed using EndNote X1, and from secondary searches. Search terms were 'laser acupuncture', 'laser therapy', 'wound healing', 'pain relief', 'inflammation', 'blood flow', 'endorphin production', 'enkephalin production', 'tissue regeneration', 'growth factor' and 'cytokine'.
Results: A total of 31 relevant papers were included in the review which comprised 15 human studies and 16 animal studies (mostly in the rat). Taken overall, results consistently demonstrated the potential of laser irradiation to reduce pain and inflammation, improve blood flow, and stimulate wound repair.
Conclusions: The consensus from the included studies on laser acupuncture and laser-stimulated wound healing is positive in terms of supporting the rationale for application of laser to decrease pain and inflammation, improve blood flow, and increase tissue regeneration.