The diagnostic performance of a newly described  variable was assessed in an in vivo model of disc degeneration using a  split-pair experimental design.


To determine if vertebral displacement measures  generated from ultrasonic indentation could distinguish between  experimental and control groups of animals.


Few procedures are available that  noninvasively assess subcutaneous vertebral mechanics. Information from  such a procedure would be of value in determining potential clinical  relevance of spinal mechanics with respect to low back pain.


Eight adolescent pigs underwent endplate perforation  surgery to initiate lumbar disc degeneration. After 4 months of  recovery, these and eight age-matched controls were assessed by  ultrasonic indentation, a noninvasive procedure that quantifies  vertebral displacements in the plane of loading-indentation. Each animal  then received a facetectomy and was reindented at the same location as  confirmed by ultrasonic imaging. Discal materials were removed  postmortem for analysis.


Degenerative discs exhibited morphologic changes  consistent with early degenerative disc disease. Prefacetectomy  comparison of vertebral displacement measures between control and  experimental animals resulted in sensitivity, specificity, and  diagnostic accuracy values of 75.0%, 83.3%, and 77%, respectively. After  facetectomy these values increased to 87.5%, 83.3%, and 85%,  respectively. These measures of diagnostic performance were comparable  or superior to those of existing clinical techniques (invasive or  otherwise) used to assess degenerative conditions of the spine.


The results of this study suggest that noninvasive  measures of vertebral displacement are clinically significant and  possess the additional advantages of being objective and noninvasive.

Spine (Phila Pa 1976). 2001 Jun 15;26(12):1348-55. [PMID:11426151]

Author information: Kawchuk GN, Kaigle AM, Holm SH, Rod Fauvel O, Ekström L, Hansson T. Department of Orthopaedics, Sahlgrenska University Hospital, Göteborg, Sweden.