The lumbar region is a frequent site of spinal disorders, including
low-back pain, and of spinal trauma. Clinical studies have established that
abnormal intervertebral motions occur in some patients who have low-back
pain. A knowledge of normal spinal movements, with all of the inherent
complexities, is needed as a baseline. The present study documents the
complete three-dimensional elastic physical properties of each lumbar
intervertebral level from the level between the first and second lumbar
vertebrae through the level between the fifth lumbar and first sacral
vertebrae. Nine whole fresh-frozen human cadaveric lumbar-spine specimens
were used. Pure moments of flexion-extension, bilateral axial torque, and
bilateral lateral bending were applied, and three-dimensional
intervertebral motions were determined with use of stereophotogrammetry.
The motions were presented in the form of a set of six load-displacement
curves, quantitating intervertebral rotations and translations. The curves
were found to be non-linear, and the motions were coupled. The ranges of
motion were found to compare favorably with reported values from in vivo
studies.