Methods and apparatus for improving shear loading capacity of a spinal segment

Abstract

A method for improving shear loading capacity of a spinal segment having a superior vertebra, an inferior vertebra or sacrum, and a facet joint, includes providing a constraint device having an upper portion, a lower portion and a compliance member coupled therebetween. The constraint device is coupled with the spinal segment such that the upper portion of the constraint device is coupled with the superior vertebra and the lower portion of the constraint device is coupled with the inferior vertebra or a sacrum. The constraint device provides a force resistant to flexion of the spinal segment. Also, length or tension in the constraint device is adjusted so as to increase engagement between an upper portion of the facet joint and a lower portion of the facet joint, thereby increasing capacity of the spinal segment to resist shear loading.

What is claimed is: 
     
         1 . A method for reducing or eliminating further progression of degenerative spondylolisthesis in a spinal segment without fusion thereof, said method comprising:
 coupling a constraint device with the spinal segment, wherein the constraint device provides a force resistant to flexion of the spinal segment without substantially restricting extension; and   adjusting length or tension in the constraint device so as to increase engagement between an upper portion of the facet joint and a lower portion of the facet joint, thereby increasing capacity of the spinal segment to resist shear loading.