Sex Differences in Predicting Chronicity of Low-Back Pain After Acute Trauma Using Lumbar Muscle Area

OBJECTIVE: The aim of this study was to investigate sex differences in predicting chronicity of low-back pain after acute trauma using cross-sectional areas of paraspinal (multifidus and erector spinae) and psoas muscles. DESIGN: Between January 2006 and December 2010, a total of 54 patients were interviewed at least 6 mos after the trauma event. The subjects were classified into chronic low-back pain group and improved low-back pain group according to the presence of low-back pain for more than 6 mos. The cross-sectional area of the multifidus, erector spinae, and psoas muscles was measured at the level of the lower margin of the L3 and L5 vertebrae using magnetic resonance imaging. RESULTS: The cross-sectional area of the multifidus and erector spinae muscles at L5 in the chronic low-back pain group was significantly smaller than that of the improved low-back pain group (P < 0.05) in the men. There were no significant differences in the other parameters between the groups in the men. There were no significant differences in any parameters in the women. CONCLUSIONS: In the men, the cross-sectional area of the multifidus and erector spinae muscles at the lower lumbar level can be considered to be prognostic factors for the chronic low-back pain after acute trauma. The authors thus suggest that strengthening of lumbar paraspinal muscles could be helpful for preventing chronicity of low-back pain.