Intraoperative facet joint injury during anterior cervical discectomy and fusion: an experimental study.

Object: Disorders of the cervical spine can be successfully addressed by surgical intervention when the choice of such intervention takes into account the possible complications in the treated and adjacent structures. The aim of this study was to investigate the potential for intraoperative trauma in cervical zygapophysial joints and to describe possible pathological changes that may occur during cervical spine surgery.

Methods: Fifteen sheep underwent surgical intervention via an anterior cervical approach; discectomy at the C5-6 level was performed. In 10 animals, the discectomy was accompanied by titanium cage fusion. The sheep were killed immediately after completion of the operation. Radiological examination of the isolated cervical spines followed. Furthermore, the cervical spines were submitted to decalcification and incised using a microtome, and tissue sections were then studied using light microscopy.

Results: Radiological examination was used to assess vertebral alignment, vertebral body (VB) morphology, implant position, and endplate and facet joint gross morphology. Histological examination of the endplate and VB demonstrated degenerative lesions as well as cellular necrosis. The study of the facet joints at the treated as well as at adjacent segments (both above and below) revealed in some cases edema between the collagen fibers of the joint capsules, congestion, and microhemorrhages. Injuries were evident in animals in which the Caspar device was used.

Conclusions: Histopathologically confirmed lesions occurred in facet joints while anterior cervical spine surgery was being performed in sheep. The findings were indicative of trauma and, in the case of human spine surgery, could possibly account for several postoperative complications and patient complaints.