The “Pendulum Law” - How to Explain the Spinal Shape? Part I

Abstract

The author uses the classical parameters that allow studying the sagittal form of the spine, following a vertebral semantics (lordosis, kyphosis, spinopelvic parameters, and sagittal balance). Then he proposes a very different perspective that analyzes the shape of the column, not in the sagittal-coronal plane but in the vertical plane, that is, integrating gravity as a three-dimensional construction axis. Beginning with an analysis of the global body scheme of which the column is part, the muscular synergies are introduced using reference points, defining tension lines, anatomical and functional arches, highlighting the importance of the respiratory function that stabilizes the shape of the thoracolumbar spine. This shows that, whatever the pelvic or frequent anomalies, the biomechanical scheme depends on a single unique law related to gravity: the “pendulum law”. This allows us to define an ideal shaped spine, in comparison to different models, evoking the semantic practical and therapeutic interest of such a perspective.