Posterior avulsion fracture at adjacent vertebral body during cervical disc replacement with ProDisc-C - A case report

Study Design: A case report. Objective: To report posterior avulsion fractures at the adjacent vertebral bodies that occurred during cervical arthroplasty with ProDisc-C, which was thought to be related to design of the prosthesis and lack of the prudence in surgical technique. Summary of Background Data: There is no previous report on the avulsion fracture of the posterior vertebral body during cervical arthroplasty. Methods: A 32-year-old-man presented with painful numbness and weakness of the right upper extremity for 2 months. On magnetic resonance imaging and computer tomography scans, a huge disc herniation at C6-C7 segment compressing the right C7 root and the spinal cord was identified. To prevent acceleration of degeneration of the C5-C6 segment, disc replacement of the C6-C7 with the ProDisc-C after anterior discectomy was planned. Results: Nearing the end of the second chiseling with a box cutting chisel, and following further mallet impaction to insert the chisel a bit more, copious bleeding occurred. Hurried hemostasis was accomplished. The posterior central vertebral bodies of C6 and C7 were found to be fractured and avulsed bony fragments were displaced posteriorly compressing the spinal cord. The bony fragments were carefully removed and the ProDisc-C was inserted as planned. The patient recovered without neurologic deficit. Conclusions: Owing to keel design of the prosthesis, the possibility of posterior avulsion fracture of the vertebral body should always be appreciated in cervical disc arthroplasty with ProDisc-C, especially during chiseling with the box cutting chisel and inserting the prosthesis. Further, insertion of either of them beyond the posterior ends of the keel cuts made by a keel cutting chisel should not be tried.