Abstract
Because internal disc derangement is a significant factor in low back pain, it is important to devise a method of inducing internal disc injuries so that these conditions can be investigated experimentally. We have devised a method of creating internal disc disruption that can create minor or severe internal disc damage as required.
The purpose of this study is to develop a method of creating internal disc derangements, which mimic those seen physiologically.
Discogram provocation studies have shown that internal disc derangement may be associated with up to forty percent of chronic low back pain. Given that these derangements produce significant changes in disc biomechanics, lamellar thickening and vertebral body bone, creation of an injury model which mimics these derangements, would be of importance toward understanding mechanisms of back pain.
Four porcine lumbar spines were each placed in an MRI-compatible support and a plastic needle was inserted along the lateral annulus fibrosis from anterior to posterior. Compressed nitrogen was introduced at 50 PSI, 100 PSI and 150 PSI for one minute each. Axial T2 MR images were obtained after each injection. Edge detection analysis was used to determine alterations in disc morphology.
Internal disc derangement was not visualized following injection of 50 PSI, although at 100 PSI annular tears and nuclear displacement away from the injection site were visualized. These derangements increased in magnitude with 150 PSI injection.
This study demonstrates that internal disc derangements can be created by injecting air into the disc. In addition, the magnitude of derangement is a function of the magnitude of air pressure applied, as evidenced by MR images.
This technique is able to create a spectrum of derangements that has not been achieved by other disc injury models.
Funding: Support from the University of Calgary
Correspondence should be addressed to Cynthia Vezina, Communications Manager, COA, 4150-360 Ste. Catherine St. West, Westmount, QC H3Z 2Y5, Canada
