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

Abstract

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<0.001). Conclusion: This study showed that the size of the multifidus muscle in patients with chronic non-specific low back pain at L4-L5 level was smaller compared to without back pain subjects on the basis of the average size of right and left muscle. Besides, in the patient group, muscle size in one side was smaller than the other side, in a way that there was a clearly and significantly asymmetry in muscle size between both sides.in addition, difference between size was observed between the two left and right waist size in the healthy group.