A Dynamic Radiographic Imaging Study of Lumbar Intervertebral Disc Morphometry and Deformation In Vivo

Abstract

Intervertebral discs are important structural components of the spine but also are significant sources of morbidity, especially for the “low back” lumbar region. Mechanical damage to, or degeneration of, the lumbar discs can diminish their structural integrity and elicit debilitating low back pain. Advancement of reparative or regenerative means to treat damaged or degenerated discs is hindered by a lack of basic understanding of the disc load-deformation characteristics in vivo. The current study presents an in vivo analysis of the morphometry and deformation of lumbar (L2-S1) intervertebral discs in 10 healthy participants while performing a common lifting act, using novel dynamic radiographic imaging of the lumbar vertebral body motion. Data analyses show uniquely different (p < 0.05) characteristics in morphometry, normal and shear strain patterns of the L5S1 discs, while the rest of lumbar discs exhibit great similarity. In particular shear strains in L2-L5 discs exhibited stronger linear correlations (R2 ≥ 0.80) between strain changes and amount of lumbar flexion-extension motion compared to L5S1 (R2 ≤ 0.5). The study therefore advances the state of knowledge on in vivo mechanical responses of the lumbar intervertebral discs during functional tasks.

Investigation of geometric deformations of the lumbar disc during axial body rotations

“…However, most of these experiments focused on the contribution of each vertebral body to rotational motion, rather than on the changes in intervertebral disc stress. Recent studies have investigated the deformation parameters of lumbar discs [9][10][11], with most of the studies focusing on the characteristics of disc deformation during flexion-extension and weightlifting.…”

Non-Invasive Evaluation of Intradiscal Deformation during Axial Loading of the Spine Using Deformation-Field Magnetic Resonance Imaging: A Potential Tool for Micro-Instability Measurements

“…In a confirming ex vivo study, Chan et al visualized such asymmetrical right–left deformation behaviors in specimens of disc segments during the application of an axial compression load. Byrne et al [ 1 ] presented similar results in vivo and argued that the behavior might be the effect of an intrinsic variation in the disc geometry, including the shape and orientation of the cartilage endplates. This, in turn, may have introduced a variation in the distribution of the load over the disc, shifting the position of the nucleus slightly off-center [ 26 ].…”

“…While in vivo measurements of intradiscal deformation may shed light on disc pathologies and the site-specific nature of disc tears and herniations [ 20 ], they pose large technical challenges and, as such, only a few studies have presented methods for human applications. Byrne et al have presented a method based on point-wise mapping to quantify the biomechanical properties of the disc [ 1 ]. However, their method relies on multiple radiological examinations utilizing ionizing radiation and is thereby unsuitable for longitudinal follow-up studies.…”

“…The disc is a unique structure that allows the mobility of the spinal column and responds to changes in load by undergoing an instantaneous elastic deformation [ 1 , 2 ]. The composition of the disc, with an inner, more gel-like structure (nucleus pulposus) surrounded by a fibrocartilaginous circle (annulus fibrosus, is an ingenious construction distributing the compressive load within the spinal segments.…”

Investigation of Geometric Deformations of The Lumbar Disc During Axial Body Rotations

“…However, most of these experiments focused on the contribution of each vertebral body to rotational motion, rather than on the changes in intervertebral disc stress. Recent studies have investigated the deformation parameters of lumbar discs [9][10][11], with most of the studies focusing on the characteristics of disc deformation during exion-extension and weightlifting.…”