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

Objective: To assess the effectiveness of low-intensity laser therapy in th e 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 a nd 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 symm etric 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 pro bes of a 1.06 mu m 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 a s assessed by the Oswestry Disability Questionnaire, and lumbar mobility. Results: The treated group had a time-dependent improvement in two of the t hree outcome measures: perception of benefit and level of function. These r esults were most marked at the midpoint evaluation (p <.005, p <.01) and en d of treatment (p <.017, p <.001) but tended to lessen at the 1-month follo w-up (p <.10, p <.004). Lumbar mobility did not differ between the groups a t any time. All tests were two-sample t tests with unequal variances. Conclusions: Treatment with low-intensity 1.06 mu m laser irradiation produ ced a moderate reduction in pain and improvement in function in patients wi th musculoskeletal low back pain. Benefits, however, were limited and decre ased with time. Further research is warranted. (C) 1999 by the American Con gress of Rehabilitation Medicine and the American Academy of Physical Medic ine ann Rehabilitation.