Infolding of the ligamentum flavum: a cause of spinal cord compression after reduction of cervical facet injuries.

Controversy exists regarding management of cervical facet injuries. Previous literature has focused on associated disc herniations reported to cause neurologic injury upon reduction. Although rupture of the ligamentum flavum has been noted with these injuries, its clinical significance has not been examined. In this case report, we present two patients in whom neurologic deterioration occurred due to infolding of the torn ligamentum flavum with spinal cord compression after reduction of cervical facet subluxations. Both had large flaps of ligamentum flavum arising from the caudal lamina which infolded upon reduction and became trapped between the spinal cord and cephalad lamina. Both patients regained normal motor function after removal of the pathologically infolded ligamentum. Neither patient had a disc herniation, hypotensive/anemic/hypoxic event, or epidural hematoma that could have otherwise been causative of the neurologic deficit. Pathologic infolding of ligamentum flavum, in addition to extruded disc herniations, should be recognized as another potential cause for spinal cord compression with reduction of cervical facet injuries. In particular, if there is a long flap of flavum arising from the caudal lamina poised to become entrapped in the spinal canal with reduction and the patient has a congenitally narrow canal, the surgeon should consider removal of the ligamentum flavum prior to reduction.