Abstract
BackgroundThe relationship between spinal alignment and skeletal muscle mass (SMM) has attracted attention in recent years. Sagittal alignment is known to deteriorate with age, but it is not known whether this is related to paraspinal muscles. Therefore, the purpose of this study is to elucidate the role of the multifidus (MF) and psoas major (PS) muscles in maintaining global spinal alignment in patients with lumbar spinal stenosis (LSS) and/or degenerative spondylolisthesis (DS), and to analyze whether each muscles’ cross-sectional area (CSA) correlates with whole-body SMM using bioimpedance analysis (BIA).MethodsWe retrospectively evaluated 140 patients who were hospitalized for surgery to treat LSS and/or DS. Spinal alignment, CSA of spinal muscles, and body composition parameters were measured from full-length standing whole-spine radiography, MRI, and BIA before surgery. The following standard measurements were obtained from radiographs: sagittal balance (C7-SVA), cervical lordosis (CL; C2–C7), lumbar lordosis (LL; L1–S1), thoracic kyphosis (TK; T5–T12), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS).ResultsThe average PS CSA (AveCSA) was highest at L4-L5, whereas MF AveCSA was highest at L5-S1. Paraspinal muscle CSAs were greater in males than in females. There was no statistically significant difference between the left and right CSA for either MF or PS. Correlation coefficient showed strong correlations between the PS AveCSA (L4-L5) and whole body SMM (r = 0.739). Correlation coefficient analysis also showed weak correlation between SMM and PT (r = − 0.184). Furthermore, PS AveCSA (L4-L5) correlated with the PT (r = − 0.183) and age (r = − 0.156), while PT correlated with the whole body SMM (r = − 0.184) but not with age.ConclusionsWhole body SMM showed correlation with PS AvCSA (L4-L5) and with PT among the spinal parameters, which was the same result in MF AvCSA (L4-L5). These findings suggest that the posterior inclination of the pelvis may be correlated with paraspinal muscle area rather than age.
Highlights
The relationship between spinal alignment and skeletal muscle mass (SMM) has attracted attention in recent years
Patients were excluded when MRI images were insufficient to measure cross-sectional area (CSA) of the MF and psoas major (PS) muscles or when spinal parameters could not be accurately measured on radiographs
We examined the relationship between spinal parameters, the paraspinal muscles, and SMM, because it is well known that the spinal column and ligaments are important for maintaining spinal alignment, the relationship between sagittal alignment and paraspinal muscle CSA has not been sufficiently examined
Summary
The relationship between spinal alignment and skeletal muscle mass (SMM) has attracted attention in recent years. Bioimpedance analysis (BIA) has been used in various contexts for the measurement of the nutritional components of body composition, such as fat mass or fat-free mass, using the electrical properties of body tissues. It is easy, non-invasive, relatively inexpensive, and can be performed in almost any subject because of its portability [9]. Non-invasive, relatively inexpensive, and can be performed in almost any subject because of its portability [9] It has recently shown promise as a tool for the measurement of water volume status of body [10, 11]
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