Relationship between morphometric and mechanical parameters of superficial lumbosacral soft tissue layers in healthy young adults

Abstract

Abstract The myotonometry is a noninvasive method capable to quantify linear elastic and viscoelastic properties of the myofascial tissue. However, this superficial layer contains different structures that have different distribution and organization of structural components. Myotonometric measurements of dynamic stiffness, logarithmic decrement and creep and ultrasonographic measurements of cutaneous tissue, subcutaneous tissue, thoracolumbar fascia and lumbar multifidus muscle thickness and echogenicity were obtained from 50 healthy individuals in the resting prone position and during contralateral arm lift. The most important findings were that, both in the relaxed and contracted lumbar multifidus state, the dynamic stiffness strongly negatively (r=-0.69; p<0.001 in relaxation, r=-0.83; p<0.001 in contraction) and creep strongly positively (r=0.79; p<0.001 in relaxation, r=0.85; p<0.001 in contraction) correlated with thicknesses of subcutaneous tissue. With lumbar multifidus contraction, the relative increase in dynamic stiffness was negatively correlated with relative decrease in dermis (r=-0.51; p<0.001) and subcutaneous tissue (r=-0.47; p=0.001), as well as positively correlated with relative increase in lumbar multifidus (r=0.36; p=0.010) thickness. Concluding, the amount of dynamic stiffness and creep of superficial soft tissues in the lumbar region predominantly depends on subcutaneous tissue thickness regardless of muscle state. Elasticity is barely affected by soft tissue morphometry. Mechanical parameters do not depend on the echogenicity (density) of soft tissues.