Open AccessPreliminary investigation of spinal level and postural effects on thoracic muscle morphology with upright open MRI
Author(s) -
Pai S Anoosha,
Zhang Honglin,
Street John,
Wilson David R.,
Brown Stephen H. M.,
Oxland Thomas R.
Publication year - 2021
Publication title -
jor spine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.125
0ISSN - 2572-1143
DOI - 10.1002/jsp2.1139
Subject(s) - supine position , medicine , lumbar , anatomy , sitting , thorax (insect anatomy) , thoracic vertebrae , physical medicine and rehabilitation , lumbar vertebrae , anesthesia , pathology
Objective Spinal‐muscle morphological differences between weight‐bearing and supine postures have potential diagnostic, prognostic, and therapeutic applications. While the focus to date has been on cervical and lumbar regions, recent findings have associated spinal deformity with smaller paraspinal musculature in the thoracic region. We aim to quantitatively investigate the morphology of trapezius (TZ), erector spinae (ES) and transversospinalis (TS) muscles in upright postures with open upright MRI and also determine the effect of level and posture on the morphological measures. Methods Six healthy volunteers (age 26 ± 6 years) were imaged (0.5 T MROpen, Paramed, Genoa, Italy) in four postures (supine, standing, standing with 30° flexion, and sitting). Two regions of the thorax, middle (T4‐T5), and lower (T8‐T9), were scanned separately for each posture. 2D muscle parameters such as cross‐sectional area (CSA) and position (radius and angle) with respect to the vertebral body centroid were measured for the three muscles. Effect of spinal level and posture on muscle parameters was examined using 2‐way repeated measures ANOVA separately for T4‐T5 and T8‐T9 regions. Results The TZ CSA was smaller (40%, P = .0027) at T9 than at T8. The ES CSA was larger at T5 than at T4 (12%, P = .0048) and at T9 than at T8 (10%, P = .0018). TS CSA showed opposite trends at the two spinal regions with it being smaller (16%, P = .0047) at T5 than at T4 and larger (11%, P = .0009) at T9 than at T8. At T4‐T5, the TZ CSA increased (up to 23%), and the ES and TS CSA decreased (up to 10%) in upright postures compared to supine. Conclusion Geometrical parameters that describe muscle morphology in the thorax change with level and posture. The increase in TZ CSA in upright postures could result from greater activation while upright. The decrease in ES CSA in flexed positions likely represents passive stretching compared to neutral posture.