Changes in Shear Modulus of the Lumbar Multifidus Muscle During Different Body Positions

The objective of this study is to evaluate localized force production capability in multifidus muscle using ultrasound shear wave elastography (SWE) in healthy individuals. Three different body positions were considered: lying prone, sitting up, and sitting up with the right arm lifted. These positions were chosen to progressively increase multifidus contraction and to minimize body motion during measurements. Shear modulus was measured at the superficial and deeper layers of the multifidus. Repeatability and possible sources of error of the shear modulus measurements were analyzed. Multifidus shear modulus (median (interquartile range)) increased from prone, i.e., 16.15 (6.69) kPa, to sitting up, i.e., 27.28 (15.72) kPa, to sitting up with the right arm lifted position, i.e., 45.02 (25.27) kPa. Multifidi shear modulus in the deeper layer of the multifidi was lower than the superficial layer, suggesting lower muscle contraction. Intraclass correlation coefficients (ICCs) for evaluation of shear modulus by muscle layer were found to be excellent (ICC  = 0.76–0.80). Results suggest that the proposed protocol could quantify local changes in spinal muscle function in healthy adults; further research in patients with spine pathology is warranted.
Source: Journal of Biomechanical Engineering - Category: Biomedical Engineering Source Type: research