Laser therapy: A randomized, controlled trial of the effects of low-intensity Nd:YAG laser irradiation on musculoskeletal back pain

Abstract

Objective: To assess the effectiveness of low-intensity laser therapy in the treatment of musculoskeletal low back pain. Design: A double-masked, placebo-controlled, randomized clinical trial. Setting: A physical medicine and rehabilitation clinic. Participants: Sixty-three ambulatory men and women between the ages of 18 and 70yrs with symptomatic nonradiating low back pain of more than 30 days' duration and normal neurologic examination results. Intervention: Subjects were bloc randomized into two groups with a computer-generated schedule. All underwent irradiation for 90 seconds at eight symmetric points along the lumbosacral spine three times a week for 4 weeks by a masked therapist. The sole difference between the groups was that the probes of a 1.06μm neodymium: yttrium-aluminum-garnet laser emitted 542mW/cm 2 for the treated subjects and were inactive for the control subjects. Main Outcome Measures: Subject's perception of benefit, level of function as assessed by the Oswestry Disability Questionnaire, and lumbar mobility. Results: The treated group had a time-dependent improvement in two of the three outcome measures: perception of benefit and level of function. These results were most marked at the midpoint evaluation ( p < .005, p < .01) and end of treatment ( p < .017, p < .001) but tended to lessen at the 1-month follow-up ( p < .10, p < .004). Lumbar mobility did not differ between the groups at any time. All tests were two-sample t tests with unequal variances. Conclusions: Treatment with low-intensity 1.06μm laser irradiation produced a moderate reduction in pain and improvement in function in patients with musculoskeletal low back pain. Benefits, however, were limited and decreased with time. Further research is warranted.