Mechanical behavior of the human lumbar and lumbosacral spine as shown by three-dimensional load-displacement curves.

TLDR

The lumbar spine is a common site of disorders and trauma, with abnormal intervertebral motions linked to low‑back pain, underscoring the need for a baseline of normal spinal movements. The study documents the complete three‑dimensional elastic properties of each lumbar intervertebral level from L1–L2 to L5–S1. Nine fresh‑frozen cadaveric lumbar spines were subjected to pure flexion‑extension, axial torque, and lateral bending moments, and three‑dimensional intervertebral motions were captured with stereophotogrammetry to produce six load‑displacement curves. The resulting load‑displacement curves were nonlinear and coupled, with ranges of motion comparable to in‑vivo values.

Abstract

The lumbar region is a frequent site of spinal disorders, including low-back pain, and of spinal trauma. Clinical studies have established that abnormal intervertebral motions occur in some patients who have low-back pain. A knowledge of normal spinal movements, with all of the inherent complexities, is needed as a baseline. The present study documents the complete three-dimensional elastic physical properties of each lumbar intervertebral level from the level between the first and second lumbar vertebrae through the level between the fifth lumbar and first sacral vertebrae. Nine whole fresh-frozen human cadaveric lumbar-spine specimens were used. Pure moments of flexion-extension, bilateral axial torque, and bilateral lateral bending were applied, and three-dimensional intervertebral motions were determined with use of stereophotogrammetry. The motions were presented in the form of a set of six load-displacement curves, quantitating intervertebral rotations and translations. The curves were found to be non-linear, and the motions were coupled. The ranges of motion were found to compare favorably with reported values from in vivo studies.