The size and symmetry of the lumbar multifidus muscles in Iranian industrial workers with and without chronic non-specific low back pain

Background: There is no specific cause of low back pain for eighty-five percent of cases and they were classified as non-specific low back pain. In this study, the size and symmetry of the lumbar multifidus muscles in industrial workers with non-specific chronic low back pain and healthy workers were investigated. Materials and Methods: In a cross-sectional comparative study, sixty industrial workers were divided into two groups of chronic low back pain and healthy, based on medical history and physical test. Roland-Morris Low Back Pain Questionnaire were filled by the group with chronic low back pain and dimensions of lumbar multifidus muscles in the L4-L5 level were measured by ultrasonography and the atrophy and asymmetry of two sides were examined. Results: Average size of right muscle in patients ranged between 2.5 and 4.3 CM? Inch? with average of 3.6 +/- 0.43 and size of left muscle was in the range of 2.8 to 4.7 with the average of 3.9 +/- 0.46. Size of right Muscle in healthy group was between 3.6 and 4.9 with the average of 4.3 +/- 0.4 and left muscle size in healthy group was in the range of 3.9 to 5.09 and average of 4.4 +/- 0.42 (p<0.001). The proportion of symmetry, in the patient group was less (0.9) compared to those with no symptoms (0.95) (p