Summary Cervical lateral mass fracture separations of the lateral mass-facet are uncommon cervical spine injuries characterized by a high degree of instability and neurologic deficits Diagnosis is made using a CT scan of the cervical spine Treatment usually involves posterior decompression and two-level instrumented fusion Epidemiology Demographics male:female ratio 2:1 mean age 35 y/o (20-70 y/o) Anatomic location C6 > C5 > C7 > C4 > C3 Etiology Pathophysiology mechanism of injury traffic accident, fall, or heavy object landing on the head hyperextension, lateral compression, and rotation of the cervical spine Associated conditions instability affects 2 levels login to view 1 more bullet anterior translation (listhesis) fractured vertebrae (77%) superior adjacent vertebrae (24%) inferior adjacent vertebrae (10%) coronal translation (33%) vertebral body collapse (33%) less common in type A separation fracture subtypes Classification Kotani classification Kotani Classification Fracture Type Fracture Description Rates of Anterior Translation (Same Level) Rates of Anterior Translation (Adjacent Level) Type A: Separation fracture Two fracture lines in unilateral lamina and pedicle 91% 20% Type B: Comminution type Multiple fracture lines with lateral wedging in the coronal plane 50% Type C: Split type Vertical fracture line in the coronal plane with invagination of the superior articular process of the caudal vertebra 80% 0% Type D: Traumatic spondylolysis Bilateral horizontal fracture lines of the pars interarticularis, leading to separation of the anterior-posterior spinal elements 100% 50% Presentation History common mechanisms (Allen and Ferguson classification) extension-compression lateral flexion login to view 1 more bullet flexion-distraction Symptoms neurologic symptoms common (up to 66%) radicular pain, radiculopathy, or spinal cord injury/myelopathy can be classified by Frankel grade or ASIA impairment scale Physical exam inspection torticollis and/or paravertebral muscle spasm neurovascular radicular pain and numbness myelopathy Imaging Radiographs recommended views AP, lateral, and oblique findings disc space narrowing often difficult to detect on plain radiographs instability login to view 3 more bullets sensitivity and specificity low sensitivity login to view 1 more bullet CT indications further evaluation of fracture morphology login to view 4 more bullets findings translation of fractured/adjacent vertebrae in sagittal and coronal planes uncovertebral joint subluxation degree of vertebral body destruction MRI findings disruption of ligaments login to view 3 more bullets disruption of intervertebral disc bone bruising Treatment Nonoperative NSAIDs, rest, and immobilization indications login to view 2 more bullets techniques login to view 2 more bullets outcomes login to view 4 more bullets Operative posterior decompression and two-level instrumented fusion indications login to view 3 more bullets techniques login to view 2 more bullets outcomes login to view 2 more bullets two-level ACDF indications login to view 1 more bullet techniques login to view 2 more bullets single posterior pedicle screw indications login to view 1 more bullet anterior and posterior decompression and fusion indications login to view 2 more bullets Complications Vertebral artery injury from pedicle screw placement Late kyphotic deformity Late instability (anterior translation) Chronic neck pain Radiculopathy