Updated: 6/23/2021

Cervical Lateral Mass Fracture Separation

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https://upload.orthobullets.com/topic/2000/images/type_a_separation.jpg
https://upload.orthobullets.com/topic/2000/images/type_b_comminution.jpg
https://upload.orthobullets.com/topic/2000/images/type_c_split.jpg
https://upload.orthobullets.com/topic/2000/images/pedicle_screw_system.jpg
https://upload.orthobullets.com/topic/2000/images/single_pedicle_screw.jpg
  • Summary
    • Cervical Lateral Mass Fracture Separations of the lateral mass-facet are uncommon cervical spine injuries characterized by a high degree of instability and neurological deficits.
    • Diagnosis is made with CT scan of the cervical spine.
    • Treatmet is usually posterior decompression and two-level instrumented fusion. 
  • Epidemiology
    • Demographics
      • male : female ratio = 2:1
      • mean age 35 yrs (20-70yrs)
    • Anatomic location
      • C6 > C5 > C7 > C4 > C3
  • Etiology
    • Pathophysiology
      • mechanism of injury
        • traffic accident, falls, heavy object landing on head
        • hyperextension, lateral compression and rotation of the cervical spine
    • Associated conditions
      • instability
        • affect 2 levels
          • because of involvement of the superior facet and inferior facet on either side of the fractured articular mass
      • anterior translation (listhesis)
        • fractured vertebrae (77%)
        • superior adjacent vertebrae (24%)
        • inferior adjacent vertebrae (10%)
      • coronal translation (33%)
      • vertebral body collapse (33%)
        • lower 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
      2 fracture lines of unilateral lamina and pedicle
      91%
      20%
      Type B - Comminution type
      Multiple fracture lines with lateral wedging in 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
      • commonest mechanisms (Allen and Ferguson classification)
        • extension-compression
        • lateral flexion
          • results in Type B Comminuted subtype
        • 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, paravertebral muscle spasm
      • neurovascular
        • radicular pain and numbness
        • myelopathy
  • Imaging
    • Radiographs
      • recommended views
        • AP, lateral, oblique views
      • findings
        • disc space narrowing
        • often difficult to detect on plain radiographs
        • instability
          • >3.5mm displacement
          • >10deg kyphosis
          • >10deg rotation difference compared with adjacent vertebra
      • sensitivity and specificity
        • low sensitivity
          • 38% pickup rate on plain radiographs
    • CT
      • indications
        • to further evaluate fracture morphology
          • fracture line extends
            • rostrally/caudally into adjacent superior/inferior facets
            • ventrally into foramen transversarium, transverse process and pedicle
            • dorsally into lamina
      • findings
        • translation of fractured/adjacent vertebrae in sagittal and coronal planes
        • uncovertebral joint subluxation
        • degree of vertebral body destruction
    • MRI
      • findings
        • disruption of ligaments
          • 50-75% rupture of anterior longitudinal ligament (ALL)
          • 30-35% disruption of posterior longitudinal ligament (PLL)
          • 10-75% disruption interspinous and supraspinous ligaments (ISL and SSL)
        • disruption of intervertebral disc
        • bone bruising
  • Treatment
    • Nonoperative
      • NSAIDS, rest, immobilization
        • indications
          • stable injuries without neurological deficit
          • hyperextension/rotation is poorly immobilized in a halo
        • techniques
          • Miami J collar
          • halo vest
        • outcomes
          • long term results of non-operative treatment are less desirable
          • may be successful in the absence of instability
          • surveillance is necessary to detect late instability and persistent pain
          • spontaneous fusion rate is only 20%
    • Operative
      • posterior decompression and two-level instrumented fusion
        • indications
          • most cases require surgery
          • main injured structures are posterior, thus preferred approach is posterior
          • also indicated for nonoperatively managed cases with late instability and persistent pain
        • techniques
          • two-level lateral mass or pedicle screw and rod fixation
          • lateral mass plating
        • outcomes
          • risk of anterior disc space collapse and late kyphotic deformity
          • midline fusion does not control rotation
      • two-level ACDF
        • indications
          • if mostly reduced and dont need posterior approach to obtain direct reduction
          • controls anterior collapse and rotation
        • techniques
          • using iliac crest bone graft
      • single posterior pedicle screw
        • indications
          • Type A Separation fracture without instability
      • anterior and posterior decompression and fusion
        • indications
          • if additional anterior column support is needed
          • if anterior approach is attempted initially, with unsuccessful reduction because of complicated fracture morphology or late presentation
  • Complications
    • Vertebral artery injury
      • from pedicle screw placement
    • Late kyphotic deformity
    • Late instability (anterior translation)
    • Chronic neck pain and radiculopathy
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Questions (1)

(OBQ11.270) A 40-year-old male patient fell asleep at the wheel and was involved in a motor vehicle accident. At the emergency room, he presented with an ASIA C spinal cord injury. An AP radiograph is shown in Figure A. An axial CT scan at the C5 level is shown in Figure B. Management of this injury should include:

QID: 3693
FIGURES:
1

Anterior cervical discectomy and fusion of C5-6

8%

(446/5256)

2

Corpectomy of C5 and instrumented fusion C5-6

3%

(152/5256)

3

Corpectomy of C5 and instrumented fusion C4-5

2%

(109/5256)

4

Posterior instrumented fusion of C4-6

80%

(4211/5256)

5

Posterior instrumented fusion of C5-6

6%

(303/5256)

L 2 C

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