Influence of thoracolumbar fascia stretching on lumbar back muscle stiffness: A supersonic shear wave elastography approach.

The lumbar paraspinal muscle compartment (PMC) is a stabilizing system of the spine whose efficiency depends on its elastic properties, which may be quantifiable by supersonic shear wave elastography (SWE). The thoracolumbar fascia (TLF) encapsulates the lumbar paraspinal muscles (LPM) and creates a PMC. Tensioning of the TLF via the stretching of the latissimus dorsi is supposed to increase stiffness within the PMC. The aims of this study were (1) to test the reliability of SWE in the multifidus and the erector spinae (ES) in prone and sited position; (2) to investigate the role of the tensioning of the pTLF, via stretching of the latissimus dorsi (LD), on LPM stiffness. Stiffness of ES and multifidus was measured using SWE at L3-L4 in procubitus and seated position in 15 participants. Stretching of LD was performed with arm elevation. Parametric paired tests, multiple analyses of variance, and intraclass correlation were used for statistical analysis. Reliability estimates were fair to excellent. Reliability was greater in ES than the multifidus, greater in seated position than during rest. Stiffness was greater in the ES than in multifidus, and in seated position than at rest. Tensioning of the TLF via LD stretching did not generate significant LPM stiffness changes. SWE is a reliable tool for assessing stiffness in the LPM. Reliability of SWE protocols is improved during seated position. Tensioning of the TLF via LD stretching did not influence LPM stiffness. Clin. Anat. 32:73-80, 2019. © 2018 Wiley Periodicals, Inc.