Abstract
In order to evaluate the influence of injury to the intervertebral disc, supraspinal ligament, interspinal ligament, and facet joint on the spinal deformation, we conducted a bending test in a total of 8 directions, i.e., flexion, extension, right lateral bending, left lateral bending, right anterolateral bending, left anterolateral bending, right posterolateral bending, and left posterolateral bending, using the 6-axis material testing machine we developed for this study. The study closely investigated changes in the range of motion (ROM) of the functional spinal unit (FSU) associated with injury using 2 FSUs of the lumbar spines obtained from human cadavers. The results showed that when the intervertebral disc was injured, the ROM increased equally in all directions. When the supraspinal ligament and interspinal ligament were injured, the ROM increased only in the flexion. When the facet joint was injured, the ROM increased in the flexion and extension. These finding indicated that, in the ROM of the lumbar vertebrae, the intervertebral disc was involved in all directions, and the supraspinal ligament and interspinal ligament were involved mainly in the flexion, while the facet joint was involved mainly in the flexion and extension.
