Article

One main question in spinal kinematics is the determination of the spine's
apparent axial center of rotation. Previous research on this topic has yielded
contradictory results. The objective of this study was to determine the apparent
axial center of rotation for seven lumbar and six thoracic spinal segments by
developing and validating a new method. A custom six-degree-of-freedom device,
allowing full range of motion, was used with motion recording and analysis
software. This system tracked a grid of markers on a specimen when rotational
torque was applied in both clockwise and counterclock wise directions at 3.53 Nm,
7.05 Nm, 10.58 Nm, and 14.10 Nm. The area encompassing the apparent axial center
of rotation was determined by identifying the five markers with the least amount
of motion. The marker angular displacement was calculated as the angle between a
virtual line drawn between two points in the initial and final torque conditions.
Rotation in both directions was averaged. The lumbar and thoracic spinal segments
averaged an apparent axial center of rotation at the posterior border of the
vertebral endplates and the anterior border of the spinal canal, with average
clockwise to counterclockwise angular displacement ratios of 0.87 and 0.97,
respectively.

Langue : ANGLAIS