1. Spinal Ligamentous Injuries Magnetic Resonance Imaging Evaluation
Vijay Pande, MD
Richard Gray, MD
Sridhar Shankar, MD
Geoffrey Goodin, MD
Rafal Kedzierski, MD
University Of Tennessee Health Science Center
Memphis, TN

2. Disclosure
The authors have no financial disclosures to make.

3. Objectives of the exhibit
To make the reader aware of spinal ligament anatomy especially pertaining to that seen on MRI.
Discuss the traumatic ligamentous injuries commonly encountered, mechanism of injuries, and the associated MRI appearance.
Discuss the clinical implications of spinal ligamentous injuries.

4. Introduction
Osseous structures and spinal ligaments are equally important in stability of the vertebral column and failure of either of them can result in spinal instability.
MRI of spine in trauma is usually performed a) To assess ligamentous integrity as part of pre-operative planning when significant osseous trauma and instability is detected on CT scanning or radiographs, b) In assessment of spinal cord status and in c) Symptomatic patients with normal radiographs and CT scan.

5. Anatomy of spinal ligaments at Craniocervical junction
Anatomy of spinal ligaments at Craniocervical junction. External craniocervical ligaments.
These unite the cranium with atlas and axis.
Anterior atlanto-occipital membrane: Wide dense band between anterior margins of foramen magnum and upper border of anterior arch of atlas. Reinforced in by extension of the anterior longitudinal ligament.
Posterior atlanto-occipital membrane: This is thinner and extends between posterior margin of foramen magnum and the posterior arch of atlas.
Posterior atlanto-axial ligament: connects the posterior arches of the atlas and axis.
Articular capsules of the atlanto-occipital joints: These surround joints between occipital condyles and superior atlantal facets
Ligamentum nuchae: Extends from the external occipital protuberance, posterior tubercle of atlas and spinous processes of the cervical vertebrae.
Ligamentum flavum: Connects the laminae of adjacent vertebrae.
Image from

6. Anatomy of spinal ligaments at craniocervical junction
Anatomy of spinal ligaments at craniocervical junction. Internal craniocervical ligaments.
Tectorial membrane: Extension of the posterior longitudinal ligament from the posterior surface of the body of axis to the anterior and anterolateral margins of foramen magnum.
Transverse ligament of atlas: Extends horizontally behind dens attached on either side on the medial side of lateral mass of atlas. Transverse ligament together with superior and inferior longitudinal fascicles forms the cruciform ligament.
Alar ligaments: These extend from the superolateral aspects of dens to the occipital condyles.
Apical ligament: From apex of dens to the anterior mid foramen magnum.

7. Upper cervical spine MR ligament anatomyB 1 2 3 7 4 9 4 8 5 6
Figures A & B: Anterior atlanto-occipital membrane(1); Tectorial membrane(2); Posterior atlanto-occipital membrane(3); Transverse ligament(4); Anterior longitudinal ligament(5); Posterior longitudinal ligament(6); Dens(7); Vertebral artery(8); Posterior atlantoaxial memebrane(9).

8. Main stabilizers at craniocervical junction2 1 1 3 4
The alar ligaments.
Transverse ligament.
Tectorial membrane.
The alar ligaments prevent excessive rotation and lateral flexion and the transverse ligament prevents anterior dislocation of atlas on axis during flexion. 1 1 5
Alar ligaments(1); Occipital condyle(2); Dens(3); vertebral artery(4); Transverse ligament(5).

9. Anatomy of spinal ligaments.
Anterior longitudinal ligament: Extends from the anterior tubercle of atlas to the sacrum.
Posterior longitudinal ligament: lies behind the vertebral bodies and extends from axis to sacrum. It continues as tectorial membrane in its upper extent.
Ligamentum Flava: Extend from anteroinferior aspect of the lamina above to the posterior surface of lamina below.
Supraspinal ligaments: These interconnect the tips of spinous processes from C7 through sacrum. Above C7 it continues as ligamentum nuchae.
Articular capsules of facet joints. 1 2 4 3 5 6
Supraspinous ligament(1); Interspinous ligament(2); Ligamentum flavum(3);Anterior longitudinal ligament(4);Posterior longitudinal ligament(5); Dura(6).

10. MRI Protocol for assessing ligamentous integrity.
Fat-suppressed, T2-weighted sequence is the most helpful in defining injured ligaments.
A typical protocol should include
T1, T2, and STIR sequences in the Sagittal plane.
GRE or T2 weighted axial.
T2 weighted isometric sequences(e.g.T2 SPACE) are helpful in evaluation of ligaments at the craniocervical junction.

11. MR imaging Features in ligamentous injuries and instability.
Normal ligaments have a hypointense signal intensity on all routine MR sequences.
Injured ligaments may show either
Disruption of the hypointense signal suggesting discontinuity.
Hyperintense signal on T2 weighted sequences suggesting injury, edema, hemorrhage.
Other radiological features of ligamentous injury and spinal instability include:
Translation greater than 2 mm indicating ligamentous disruption.
Widening of the interspinous distance, widening of the facet joints.
Disruption of the posterior vertebral body line, widening of the intervertebral canal. Vertebral body height loss of greater than 50%, and kyphosis of greater than 20°.

12. Mechanism of spinal injuries.
Cervical spine injuries mechanisms include
Hyperflexion or Hyperflexion with rotation.
Hyperextension or Hyperextension with rotation.
Vertical compression.
Lateral flexion.
However many mechanism may act simultaneously resulting in complex injuries.

13. 3-column theory of Denis
Anterior column : Anterior vertebral body, the anterior longitudinal ligament, and the anterior annulus fibrosis.
Middle column: Posterior vertebral body, the posterior longitudinal ligament, and the posterior annulus.
Posterior column: Includes the pedicles, the lamina, the facets, and the spinous processes, ligamentum flavum, interspinous, and supraspinous ligaments, facet joint capsules.
Any two column fracture is considered unstable.
ANTERIOR
ANTERIOR
MIDDLE
POSTERIOR

14. Upper cervical spine injuries
Upper cervical spine injuries are particularly important due to the frequent association with severe trauma and magnitude of potential cord injury.
Upper cervical spine injuries include trauma to the occipital condyles, the atlanto-occipital articulation, C1 (Jefferson’s fracture), C2 (Hangman’s fracture) and fractures of the odontoid process and the atlantoaxial joint.
Atlanto-occipital dislocation is a result of disruption of the stabilizing ligaments between the occiput and C1, and is more frequent in children due to the disproportionate size of the cranium.
Atlanto-occipital dislocation has a high associated fatality rate because of critical CNS injuries, which results in respiratory arrest.

15. Hyperflexion injuries
Hyperflextion injuries resulting in anterior subluxation : Occur in the cervical spine when the posterior ligament complex is disrupted but the anterior longitudinal ligament remains intact. The facet joints may be subluxed.
Flexion tear drop fracture: Result in fracture dislocation of the cervical spine. Usually with complete disruption of the anterior longitudinal ligament, the intervertebral disc, and the posterior longitudinal ligament. There is a substantial axial force component, which causes the impacted vertebral body fracture and is frequently associated with spinal cord injury.
Bilateral facetal dislocation: Hyperflexion injury that occurs following a severe flexion force to the head and neck, causing anterior displacement of the spine and three column ligamentous injury at the level of the subluxation. Facets can be subluxed, perched, or locked.
Flexion rotation injuries: Flexion and rotation may result in dislocation of one facet with tearing of the posterior ligaments.

16. Extension injuries
Hyperextension injuries occur with forceful posterior displacement of the head or upper cervical spine, usually from trauma to the face or sudden deceleration, such as in a motor vehicle accident.
Frequently the anterior longitudinal ligament, the intervertebral disc, and the posterior longitudinal ligaments are injured.
Patients with ankylosing spondylitis or DISH are particularly prone to extension type fractures. These patients suffer fractures of the pathologic anterior calcified ligaments that extend obliquely through the disc into the subjacent vertebral body or posteriorly through the disc space.
Extension teardrop fracture : These occur when a hyperextension force produces an avulsion fracture of the anteroinferior corner of C2.

17. Disruption of the tectorial membrane, anterior atlanto-occipital membrane and posterior atlanto-axial ligament. 1 2 3
Anterior atlanto-occipital membrane
Tectorial membrane.
posterior atlanto-axial ligament

18. Alar ligament injury. A C B D
Coronal T2 SPACE & Axial T2 MR : Disruption of right alar ligament green arrows (A&B); Injured left alar ligament green arrows(C&D). Intact opposite side alar ligaments blue arrows.

19. Ligamentum Flavum and interspinous ligament injury.
Sagittal STIR of cervical spine: Discontinuity in the hypointense signal of ligamentum flavum(1) and hyperintense signal in interspinous ligament(2) suggesting injury. 2 1

20. Multiple ligament injuries
Sagittal STIR MR:
Discontinuity and hyperintense signal involving Anterior longitudinal ligament(1); posterior longitudinal ligament(5); ligamentum flavum(3); and interspinous ligaments(4); with prespinal fluid collection(2). 3 1 4 5 2

21. Supraspinous ligament and ligamentum nuchae injuries.
Supraspinous ligament and ligamentum nuchae connect the tips of the spinous processes in thoracic spine and cervical spine respectively.
STIR sagittal MR: Discontinuity and hyperintense signal involving the supraspinous and ligamentum nuchae (green arrows). Also injury to anterior longitudinal ligament.(red arrow)

22. Facet joint capsule injury
Facet joint capsules form important component of the posterior ligament complex.
Injury to facet joint capsules result in spinal instability, the facets can become dislocated, locked or perched resulting in anterior subluxation of vertebrae.
STIR Coronal & MEDIC axial MR: Hyperintensity of facet joints with facet joint diastasis

23. Thoracolumbar spine injuries
Thoracolumbar fractures are common at the thoracolumbar junction.
Major thoracolumbar spine injuries:
Compression wedge fracture.
Burst, flexion distraction, or Chance fractures.
Fracture dislocation.

24. Chance fracture
Classic lap-belt injury (Chance fracture): Compression of the anterior column with distraction of the middle and posterior columns with horizontal fracture through the spinous process, the lamina, the pedicles, the intervertebral disc space, and the posterior longitudinal, supraspinous, and intraspinous ligaments.
Anterior longitudinal ligament is generally intact but may be disrupted in severe injuries.
Commonly occurs at L1-L3.

25. Posterior ligament complex in thoracolumbar region.
Posterior ligament complex(PLC) in the thoracolumbar spine is composed of :
Supraspinous ligament
Interspinous ligaments
Ligamentum flavum
Facet capsules
Thoracolumbar fascia
Integrity of the PLC is one of the most important component in stability of spine.

26. Chance fracture with disruption of posterior ligament complexB
Figure A: Sagittal CT bone window: Horizontal fracture through vertebral body(red arrow) with facet joint disruption and widened interspinous distance.
Figure B: Sagittal T2 weighted MR showing disruption of posterior ligament complex(green arrow).

27. Posterior ligament complex injury
STIR sagittal MR:
Complete facet joint disruption(1) with injuries of posterior longitudinal ligament, ligamentum flavum, interspinous and supraspinous ligaments(2) Retropulsion of vertebral body.
Subcutanous fluid collection(3) 2 1 3

28. Injuries in fused spineA B
Figures A: Sagittal CT reconstruction in bone window, Figure B: Sagittal STIR MR
Fracture through the calcified anterior longitudinal ligament and through the disc in a patient with DISH

29. Traumatic disc injuries.
Post-traumatic disc injuries can either be disc injuries or disc herniations.
Traumatic disc injury :
Narrowing or widening of the disc space.
T2 hyperintense signal due to tearing of the disc substance.
Traumatic disc herniation has a similar MR appearance to non- traumatic disc herniation.
Trivial spinal trauma in a pre-existing canal stenosis can result in severe cord contusions.

30. Disc injury
T2 weighted sagittal MR: Fracture through the disc(1) with disruption of anterior longitudinal ligament(2) and posterior longitudinal ligament(4) with a pre spinal hematoma/fluid collection(3). 1 4 2 3

31. Traumatic Disc Herniation.1 2
Sagittal STIR and axial T2 :
Acute traumatic herniation of the C6-C7 disc (3) with anterior translation of C6 over C7. Interspinous ligament (2) and paraspinal muscle (1) injuries. 3 3

32. Traumatic dural tear.
Traumatic dural tears frequently occur with leakage of cerebrospinal fluid in extra dural spaces, most of these heal spontaneously, however infrequently traumatic dural tears result in pseudomeningocele (arrow) formation especially when associated with nerve sheath tear or nerve root avulsion.
Axial T2 SPACE sequence: Right lateral cervical traumatic pseudomeningocele

33. Conclusions.
Indirect evidence of spinal ligament disruption includes palpable gap between the spinous processes on physical examination, widening/splaying of the spinous processes or facet diastasis on radiographic and CT imaging exists.
MRI is the only modality which provides the unique evidence of spinal ligamentous injuries.
Ligaments of the cranio-vertebral junction and posterior ligament complex are important determinants in spinal stability and are frequently injured in association with spinal fractures.
Recognition of spinal ligament injury is equally important in assessment of spinal instability and is important determinant in surgical intervention.

34. References
Alexander R. Vaccaro, Jeffrey A. Rihn, Davor Saravanja et al. Injury of the posterior ligamentous complex of the thoracolumbar spine: A prospective evaluation of the diagnostic accuracy of magnetic resonance imaging : Spine: 2009: volume 34; number 23;
Philip F. Benedetti, Linda M Fahr, Lawrence R. Kuhns and L. Anne Hayman: MR imaging findings in spinal ligamentous injury: AJR; September 2000 Volume 175, issue 3:
Burns, Ted.; H.Royden ; Netter, Frank H: The Netter collection of medical illustrations: Nervous system, 2nd Edition: Volume 7, part 2- Spine and peripheral motor and sensory system.
Seamus Looby, Adam Flanders: Spine trauma :Radiologic Clinics of North America: Volume 49, Issue 1, January 2011:
D. Goradia, K.F. Linnau, W.A. Cohen, S. Mirza, D. K. Hallam, C.C. Blackmore: Correlation of MR imaging findings with intraoperative findings after cervical spine trauma: Am j Neuroradiology: Feb 2007: 28:

35. Author contact details.
Dr. Vijay Pande.
Fellow in MRI : University of Tennessee Health Science Center, 920 Madison avenue Memphis Tennessee.