Full-Field Ultrasound Time-Harmonic Elastography Quantifies Task-Dependent Thoracolumbar Fascia and Multifidus Mechanics During Back Extension

The study tested a new ultrasound technique called time-harmonic elastography (THE) that maps mechanical properties of tissues. Eighteen healthy adults (9 women and 9 men) with an average age of 19.4 years participated in the research. During back extension, changes in the thoracolumbar fascia and deep spinal muscles were measured. Results showed that back extension increased shear wave speed in both tissues and decreased penetration rate. The change in shear wave speed was greater in muscles (0.62 m/s) than in fascia (0.43 m/s). This technique allows simultaneous measurement of changes in adjacent tissues during movement and confirms its potential for further clinical applications.