Basic biomechanics of the spine.

The purpose of this presentation is to provide basic biomechanical information concerning the spine, its components, and the spinal cord. It is shown that this information is helpful in understanding the fundamental functions of the spinal column. The experimentally determined physical properties of the vertebra, various spinal ligaments, the disc, and the spinal cord under many different loading conditions are described. The role of the special characteristics of the spine ligaments in allowing physiological motions of the spine, preventing excessive motions between vertebrae, and protecting the spinal cord during trauma are discussed. Movements of the spinal cord within the spinal canal and associated changes of its section during physiological movements of the spine are also described. The kinematics of the various regions of the spine are discussed and their clinical significance is presented. The problems of spinal trauma and is associated spinal instability are analyzed. Guidelines are recommended to assess spinal stability. The proper application of such guidelines will provide the basis for sound clinical judgments.