Stage de Master 2 Biomaps/IBHGC, Paris - Dynamic Assessment of Back Muscles

Dynamic Elastography of Paravertebral Muscles: Toward a New Biomarker of Lumbar Spine Disorders?Lumbar spine disorders are chronic, progressive, and unpredictable diseases representing a major public health issue. While paravertebral muscles play a key role in spinal stability, their mechanical contribution to disease onset and progression remains poorly understood.Ultrasound elastography provides a noninvasive method to quantify muscle stiffness and estimate active and passive muscle forces. Preliminary work conducted at Paris-Saclay, Bicêtre Hospital, and ENSAM has demonstrated the reproducibility of stiffness measurements and the influence of posture on paravertebral elasticity. However, static assessments fail to capture the dynamic biomechanical behavior of spinal muscles under load — a crucial aspect for understanding functional stability.We hypothesize that dynamic elastography can reveal elastic imbalances within paravertebral muscles, serving as a potential biomarker of lumbar spine dysfunction.Specific aims:

1. Develop a dynamic ultrasound elastography protocol to quantify the elasticity of the multifidus, erector spinae, and psoas muscles in prone and standing positions.
2. Assess postural variations (lumbar lordosis modulation by heel lifts) and define muscle elasticity “profiles” across different back morphotypes.
3. Integrate motion analysis (sacrolumbar angle from inertial sensors) with elastography data. 
4. Correlate muscle mechanical properties with sagittal alignment measured by EOS imaging.

This Master 2 research internship, conducted at ENSAM – IBHGC (Institut de Biomécanique Humaine Georges Charpak), is part of a broader research program aiming to characterize the elastic response of axial musculature and its clinical implications in sagittal imbalance. This feasibility study will contribute to developing a standardized dynamic elastography protocol and to establishing a data collection pipeline combining elastography, motion analysis, and EOS imaging.This work has been awarded the Société de Biomécanique Master 2 Grant, recognizing its scientific quality and its potential integration within a larger translational research initiative on spine biomechanics.