RESUMO
STUDY DESIGN: Case-control study (retrospective comparative study). OBJECTIVES: The purpose of this study was to define the relationship between low back pain (LBP) and the cross-sectional area (CSA) and density of the erector spinae muscle (ESM) and isolated multifidus muscle (IMM) on computed tomography (CT) scans of patients with a chief complaint other than LBP. SUMMARY OF LITERATURE REVIEW: Most previous studies have focused on radiographic data from patients with a chief complaint of LBP, rather than on radiographic data from patients with a chief complaint other than LBP. MATERIALS AND METHODS: This retrospective study included 475 patients who underwent CT scans between January 1, 2010 and December 31, 2010. The CSA and density of the ESM, IMM, and the psoas muscle (PM) were obtained. All measurements were calculated as the ratio of each muscle. The relationships between the CSA of each muscle and both types of LBP were analyzed. RESULTS: The ESM-to-PM ratio in terms of density was 1.227±0.797 in the LBP group and 0.645±0.732 in the non-LBP group (p=0.174). The IMM-to-PM ratio in terms of density was 0.664±0.515 in the LBP group and 0.806±0.518 in the non-LBP group (p=0.007). CONCLUSIONS: The IMM was more relevant to LBP than the ESM of the back, and density was more relevant to LBP than the CSA of regular muscles. The IMM was more useful than the ESM for analyzing LBP.