A porcine model of intervertebral disc degeneration induced by annular injury characterized with magnetic resonance imaging and histopathological findings

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Appropriate animal models of disc degeneration are critical for the study of proposed interventions as well as to further delineate the degenerative process. The purpose of this study was to characterize a porcine model for disc degeneration confirmed on magnetic resonance (MR) imaging studies and histological analysis.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Twelve miniature pigs were used (weight 48–65 kg) to study degeneration in the lumbar spine. Under fluoroscopic guidance, the disc was percutaneously punctured with a 3.2-mm-diameter trephine to a 5-mm depth into the annulus fibrosus. Control and experimental levels were randomized among 6 levels in the lumbar spine. The unlesioned spinal levels were used as controls and were compared with lesioned levels. Magnetic resonance imaging grading and disc height were serially recorded preoperatively, and at 5, 8, 19, 32, and 39 weeks postoperatively. The animals were killed in groups of 3 at 7, 18, 32, and 41 weeks postinjury, and the discs were examined histopathologically.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Consistent, sequential, and progressive degeneration of the annular injury was observed on MR imaging and histopathological studies from the time of injury to the final time point. The disc height and the disc height index also sequentially decreased from the time of the injury in a consistent manner. The uninjured control levels did not show any progressive degeneration and maintained their normal state.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Based on MR imaging and histopathological findings, the authors demonstrated and characterized a reliable model of sequential disc degeneration in miniature pigs with percutaneous injury to the annulus fibrosus. In the early stages, as soon as 5 weeks after injury, significant disc degeneration was seen on MR imaging grading with decreases in disc height. This degeneration did not improve by the final time point of 39 weeks.</jats:p></jats:sec>

Interference in the endplate nutritional pathway causes intervertebral disc degeneration in an immature porcine model

“…One disc was stabbed with a no. 23 scalpel at the left anterolateral part at a depth of 6 mm (just reaching the NP; in a pilot study, we measured the AF width to be about 6 mm) as a positive control [15,16]. In the other disc, a slice defect was created in the vertebral body both caudally and cranially to the disc by drilling and curetting.…”

“…The psoas muscle was gently detached from the intervertebral discs, and care was taken to keep the segmental artery intact. Due to variability in the number of lumbar vertebrae in pigs (five, six or seven), the disc level was selected with reference to the lumbosacral junction [15]. This reference level was set as disc 7 and the others cranial to this level were then marked in descending order to disc 0.…”

Association between Annular Tears and Disk Degeneration: A Longitudinal Study

“…10,34 Experimental models of disk degeneration have demonstrated that the loss of signal intensity of the disks accompanies various histologic changes of degeneration within the disk. 35,36 Although it is one of the factors influencing the degeneration grade on the scale suggested by Pfirrmann et al, 13 we chose to evaluate the extent of the loss of T2 signal intensity of the disks in a separate arbitrary scale, hoping that by doing so, we would be able to separate disks with relatively small differences in the extent of nuclear degeneration. Some investigators have used objective calculations of T2 relaxation times in the disks with the objective of gaining a continuous and objective measure of disk degeneration.…”

142 Intradiscal Injection of Simvastatin Results in Radiologic, Histologic, and Genetic Evidence of Disc Regeneration in a Rat Model of Degenerative Disc Disease

“…One study has shown that, of non-primates, pig spines are most similar to that of humans [52]. To date, one porcine model of disc degeneration has been developed in miniature Yucatan pigs [53]. We have developed a similar model for Yorkshire pigs that utilizes a trans-psoas approach (manuscript in preparation).…”