Comparison of the effects of low-level laser and pulsed and continuous ultrasound on pain and physical disability in chronic non-specific low back pain: a randomized controlled clinical trial

Abstract Objective To compare the short-term effects of pulsed laser and pulsed and continuous ultrasound on pain and functional disability in women with chronic non-specific low back pain. Methods The sample was composed of 100 volunteers randomly allocated into four groups: The Pulsed Laser Group (n = 26) was treated with 3 J/cm2; the Pulsed Ultrasound Group (n = 24; 3 MHz) was treated with 1 W/cm2; the Continuous Ultrasound Group (n = 26; 1 MHz) was treated with 1 W/cm2; and a Control Group (n = 24), where the patients were still waiting for treatment. Before and after 10 sessions of treatment, the intensity of pain was assessed using the visual analogue scale (VAS), the quality of pain was evaluated using the McGill pain questionnaire and functional disability was investigated using the Roland–Morris questionnaire. Results The three treated groups exhibited a decrease in pain (p < 0.001); the Pulsed Laser Group showed the greater relative gain (91.2%), Meanwhile, the Control Group exhibited a worsening of − 5.8%. The three treated groups demonstrated improvement in the quality of pain (McGill) in the total, sensory and affective dimensions (p < 0.005; p < 0.002; p < 0.013, respectively). All treated groups showed a decrease in functional disability (p < 0.001), but the Pulsed Ultrasound Group showed the highest relative gain (83.3%). Conclusions The three modalities have significant effects to decreasing low back pain and improving 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. Trial registration ClinicalTrials.gov: NCT02150096.