Bilateral Facet Dislocation with Neural Compression from an Avulsed Posterior Longitudinal Ligament

Background and Importance: A review of the literature failed to show evidence of normal appearing posterior longitudinal ligament avulsion as a cause of spinal cord compression after bilateral cervical facet dislocations. We report a case of the posterior longitudinal ligament (PLL) avulsion causing spinal cord compression after bilateral cervical facet dislocation. Clinical presentation: A 93 year female presented with upper extremity numbness and bilateral C5-C6 facet dislocations. The patient was immediately taken for closed reduction and anterior cervical decompression with fusion (ACDF). After awake, closed reduction, an ACDF was immediately performed. After a complete discectomy procedure, the spinal cord could be visualized secondary to an absent PLL. A nerve hook was used to explore behind the C6 vertebral body to decompress the spinal cord. A segment of normal appearing posterior longitudinal ligament, which had avulsed from the superior aspect of C5, was found folded behind the C6 vertebra causing cord compression. There was no herniated disk material discovered. Conclusion: In addition to herniated disk material, avulsed PLL is another potential source of cord compression after closed reduction of cervical facet dislocations and surgeons must be aware of this possible source of compression while exploring and decompressing the spinal canal. This case study elucidates that the PLL is a potential cause of spinal cord compression after traumatic bilateral cervical facet dislocations.