The Evaluation of Chronic Low Back Pain by Determining the Ratio of the Lumbar Multifidus Muscle Cross-sectional Areas of the Unaffected and Affected Sides.

[Purpose] The primary purpose of this study was to evaluate chronic low back pain by determining the ratio of the cross-sectional areas of the lumbar multifidus of the unaffected and affected sides at the L5 level using the ultrasound imaging. [Subjects and Methods] The subjects were 24 young people (10 males, 14 females) with chronic low back pain lasting for more than 6 months on one side. The visual analog scale (VAS) value of pain was assessed and the cross-sectional areas of the bilateral multifidus muscle were measured with the subjects in a supine position in a resting state using ultrasound imaging. Correlation and linear regression analysis were performed on the VAS and the ratio of the cross-sectional areas of the lumbar multifidus of the unaffected and affected sides. [Results] The VAS and the ratio of the cross-sectional areas of the lumbar multifidus were linearly correlated. [Conclusion] The results of this research indicate that when the ratio of the cross-sectional areas of the lumbar multifidus of the unaffected and affected sides increases, the symptom of chronic low back pain deteriorates.