Stiffness properties and geometry of lumbar spine posterior elements.

This paper reports measurements made in five fresh cadaver lumbar spine motion segments of the load-deformation properties of the posterior element soft tissues. These properties were measured and the stiffness corresponding to them were calculated for loading in anterior, posterior and lateral shear; in longitudinal tension and compression; and in flexion, extension, lateral bending and axial torsion. In addition, measurements were made in six motion segments of the positions of the inferior facet joint centers relative to the vertebral body centers, and of the orientations of the facet joint surfaces.