Effect of laser, continuous and pulsed ultrasound on pain, functional disability of women with non-specific low back pain: a randomized controled trial

INTRODUCTION: low back pain is often accompanied by exacerbation of pain and functional disability. Laser, Continuous and Pulsatile Ultrasound are used for the treatment, but its effects are controversial. OBJECTIVES: To assess the effect of the laser, the pulsatile and the continuous ultrasound on pain and functional disability in women with chronic non-specific low back pain. MATERIAL AND METHODS: The sample was composed of 100 volunteers randomly allocated into four groups: Laser (n= 26) treated with 3 J; Pulsed Ultrasound (n= 24) of 3 MHz, treated with 1W/cm2; Continuous Ultrasound (n= 26) of 1 MHz, treated with 1W/cm2); and a Control Group (n= 24), who waited for treatment. The intensity of pain was assessed using the Visual Analogue Scale (VAS), the quality of pain with the of the McGill pain questionnaire and the functional disability with the Roland-Morris questionnaire, before and after 10 session of treatment. RESULTS: The three treated groups had decrease in pain (p < 0.001), but the Laser group showed relative gain of 91.2 %; pulsed Ultrasound 76.8 %; group Continuous Ultrasound 81.5% and the Control group worsening of -5.8 %. The three treated groups had improvement in the quality of pain (McGill), total, sensory and affective dimension (p < 0.005; p < 0.002; p < 0.013, respectively). All treated groups showed a decrease in functional disability (p < 0.001), but the Pulsatile Ultrasound group showed the highest relative gain (83.3%) in comparison with the Laser (62.5 % ), Continuous Ultrasound (50 %) and Control groups (-37.5 % ). CONCLUSION: The pulsed laser, pulsed and continuous ultrassom have significant effects in decrease of low back pain and improve the functional disability in women with non-specific chronic low back pain, but the pulsed low level laser had the best results on pain while the pulsed ultrasound had the best results on improve the functional disability.