Clinical and Radiological Predictive Factors to be Related with the Degree of Lumbar Back Muscle Degeneration: Difference by Gender

BACKGROUND The prediction of lumbar back muscle degeneration is important because chronic low back pain and spino-pelvic imbalance have been known to be related to it. However, gender difference should be considered because there are different quality and volume of muscles between genders. The purpose of this study was to search for clinical and radiological factors to predict the degree of lumbar back muscle degeneration according to gender difference. METHODS We reviewed 112 patients (44 men and 68 women) with spinal stenosis who underwent a decompressive surgery between 1 January 2009 and 31 December 2011. Degrees of lumbar back muscle degeneration were classified into three categories by the fatty infiltration at each L3-4 disc level on the axial view of T1 magnetic resonance imaging (MRI). Age, sex, bone marrow density score, and body mass index (BMI) were obtained from chart reviews. Lumbar lordosis, sacral slope, pelvic tilt (PT), and pelvic incidence were calculated with lumbar spine standing lateral radiographs. The degrees of spinal stenosis and facet arthropathy were checked with MRI. Student t-test, chi-square test, or Fisher exact test were used to compare clinical and radiological parameters between genders. Analysis of variance (ANOVA) and linear regression analysis were used to search for a relationship between lumbar back muscle degeneration and possible predictive factors in each gender group. RESULTS Many clinical and radiological parameters were different according to gender. The age, BMI, and PT in the female group (p = 0.013, 0.001, and 0.019, respectively) and the PT in the men group (p = 0.018) were predictive factors to be correlated with lumbar back muscle degeneration. CONCLUSIONS The PT was the important predictive factor for lumbar back muscle degeneration in both, the male and the female group. However, age and BMI were predictive factors in the female group only.