Spontaneous Interbody Fusion After Controlled Injuries to the Spine: An Experimental Study in Rabbits

Abstract

To evaluate the rationale of spontaneous spine fusion after a spinal injury, the authors conducted an experimental study that consisted of three types of controlled injuries to a rabbit spine model. The first was injury to the intervertebral disk (type I injury). The second was injury of the intervertebral disk along with injury to one of the adjacent vertebral end plates (type II). In type III injury, both the opposing end plates were injured along with the intervertebral disk. In 38 rabbits, a total of 82 injuries of these three types were inflicted. Twenty-six injuries were of type I (n ‫ס‬ 22 rabbits), 26 were type II (n ‫ס‬ 24 rabbits), and 30 were type III (n ‫ס‬ 26 rabbits). Spontaneous fusion occurred only in type III injuries. From the 30 type III injuries, fusion occurred in 20 (66.6%). For an autofusion to occur, both epiphyseal plates may be injured. In the clinical situation, this observation suggests that a radiographically obscure lesion of both neighboring vertebrae may proceed to autofusion of that spinal segment observed later.

The Design and Use of Animal Models for Translational Research in Bone Tissue Engineering and Regenerative Medicine

“…The rabbit intervertebral space has a marked tendency for rapid degeneration and even spontaneous fusion following relatively minor trauma to the annulus. 84 Canine models for posterior fusion have been described with [85][86][87][88][89][90][91][92] and without 85,87 internal fixation. Goat, [93][94][95][96][97] sheep, [98][99][100][101][102][103] and pig [104][105][106][107][108][109][110] models allow more opportunity for internal fixation anteriorly or posteriorly.…”

Comparison of the Outcomes between AO Type B2 Thoracolumbar Fracture with and without Disc Injury after Posterior Surgery

“…37 In a clinical study, Wang et al 38 found that thoracolumbar burst fractures led to disc degeneration at levels adjacent to the fractured endplate. Moreover, although spontaneous fusion of facet joints and intervertebral discs has been observed after trauma, 28,39 due to the poor selfrepair ability of the intervertebral disc in vivo, lesions of intervertebral discs hinder the stability of the spine after trauma. 40,41 In that case, involvement of the endplate and disc leads to recollapse of the vertebral body, implant failure, and eventually postoperative kyphosis in patients with thoracolumbar AO Type B2 fractures.…”

“…Previous research suggests that an endplate‐disc complex injury may influence the clinical outcomes of posterior surgery for a thoracolumbar fracture 24,25 . In a few studies, spontaneous interbody fusion was observed in a disc injury with a thoracolumbar fracture 26–28 . The consequent effect of a disc injury has not been fully emphasized in clinical treatment compared to many other factors.…”

MRI of the axial skeleton in spondyloarthritis: the many faces of new bone formation

“…Post-traumatic interbody fusion is a rare phenomenon, and it has been suggested that it can only occur when both the opposing endplates and the intervertebral disc are involved in the injury (Fig. 13) [40]. Acquired vertebral fusion is desirable when surgical spinal arthrodesis is performed; however, this is beyond the scope of this review.

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