An Endplate-Based Joint Coordinate System for Measuring Kinematics in Normal and Abnormally-Shaped Lumbar Vertebrae

Abstract

Vertebral level-dependent, angular, and linear translations of the spine have been measured in 2D and 3D using several imaging methods to quantify postural changes due to loading conditions and tasks. Here, we propose and validate a semiautomated method for measuring lumbar intervertebral angles and translations from upright MRI images using an endplate-based, joint coordinate system (JCS). This method was validated using 3D printed structures, representing intervertebral discs (IVD) at predetermined angles and heights, which were positioned between adjacent cadaveric vertebrae as a gold standard. Excellent agreement between our measurements and the gold standard was found for intervertebral angles in all anatomical planes (ICC > .997) and intervertebral distance measurements (ICC > .949). The proposed endplate-based JCS was compared with the vertebral body-based JCS proposed by the International Society of Biomechanics (ISB) using the 3D printed structures placed between 3 adjacent vertebrae from a cadaver with scoliosis. The endplate-based method was found to have better agreement with angles in the sagittal plane (ICC = 0.985) compared with the vertebral body-based method (ICC = .280). Thus, this method is accurate for measuring 3D intervertebral angles in the healthy and diseased lumbar spine.

The effect of training on lumbar spine posture and intervertebral disc degeneration in active-duty Marines

“…Briefly, a set of markers was manually placed at the corners of each vertebra (L1-S1) and posterior elements to model vertebral position and orientation. Relative rotations in the axial and coronal planes between contiguous vertebrae were removed, and the resulting vertebral end-plate representations were used to generate postural measurements in the sagittal plane (Berry et al 2015).…”

Lumbar spine postures in Marines during simulated operational positions

“…Postural measurements were generated from upright MRI images in each position, using a previously validated algorithm . Briefly, digital seed points were manually placed on the corners of the vertebral body and on the posterior elements of each vertebra using OsiriX .…”

“…[17][18][19] Kinematic Measurements Postural measurements were generated from upright MRI images in each position, using a previously validated algorithm. 20 Briefly, digital seed points were manually placed on the corners of the vertebral body and on the posterior elements of each vertebra using OsiriX. 21 The locations of the seed points were imported into MATLAB (MathWorks Inc., Natick, MA) and used to define an endplate-based joint coordinate system applied to the superior and inferior endplate of each vertebra (L1-S1).…”

Intervertebral disc kinematics in active duty Marines with and without lumbar spine pathology

“…Postural measurements (IVD height, IVD angle) were generated from upright MRI images in each load configuration using a previously validated algorithm using OsiriX . Briefly, markers were manually placed on the corners of each lumbar vertebra and on the pedicles of each lumbar vertebra on consecutive sagittal MRIs using OsiriX.…”

“…The locations of each marker were imported into MATLAB (MathWorks, Natick, Massachusetts) and used to define an endplate‐based joint coordinate system, which was applied to the superior and inferior endplates of each vertebra, from which local positional measurements were made. Previously, this method has been shown to have an average absolute error of 0.77° ± 0.55° for sagittal angle measurements and 1.74 mm ± 1.11 mm for intervertebral height measurements …”