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Classification and mechanism of subaxial cervical spine injuries.pptx
- 1. Classification and Mechanism of Subaxial Cervical Spine Injuries Department of Neurosurgery Dr RE Anto 21/02/2024
- 2. Contents • Introduction • Anatomy • Mechanisms • Classification • Stability • References
- 3. Introduction • The subaxial spine is from C3 – C7 • Distinct from C1 + C2 so it's viewed as a different entity
- 4. Osseous Anatomy • Uncovertebral joint • Joint of Lushka • Lateral projections of the body • Medial to the VA • Facet joints • Sagittal orientation at 30-40 degrees • Spinous processes • Bifid • C7 prominent
- 5. Facet Joint • Zygapophyseal joints • Formed by the articular processes of adjacent vertebrae • Synovial gliding joints • Sagittal orientation 30 – 45 degrees
- 6. Lateral Mass Anatomy • Medial border • Lateral edge of lamina • Lateral border • Superior/Inferior borders • Facets • VA is anterior to the medial border of the lateral mass, enters at C6 • 4 quadrants of the lateral mass with the supero-lateral mass being safe
- 7. Ligamentous Anatomy • Anterior • ALL, PLL, Intervertebral disc • Posterior • Nuchal ligaments • Supraspinous • Interspinous • Ligamentum Flavum and the facet joint capsules
- 8. Vascular Anatomy • Vertebral artery • Originates from subclavian a. • Enters the spine at C6 foramen • At C2 turns posterior and lateral • Forms Basilar artery higher up intradural • Foramen transversarium • Gradually moves anteriorly and medially from C6 – C2.
- 9. Mechanisms of injury • Hyperflexion • Axial compression • Hyperextension • Rotatory
- 10. Hyperflexion • Distraction creates tensile forces in posterior column • Can result in compression of body (anterior column) • Most commonly results from MVA and falls
- 11. Axial Compression • Result from axial loading • Commonly from diving, football, MVA • Injury pattern depends on initial head position • May create burst, wedge or compression fractures
- 12. Hyperextension • Impaction of posterior arches and facet compression causing many types of fractures: • Lamina • Spinous processes • Pedicles • With distraction get disruption of ALL • Evaluate carefully for stability • CENTRAL CORD SYNDROME
- 13. Classification Systems • 1982: Allen and Ferguson • 1986: Harris et al OCNA • 1996: Stauffer and MacMillan Fractures • 2005: Cervical Spine Injury Severity Score (CSISS) • 2007: SLIC (Subaxial cervical spine injury classification) • 2013: AO Spine Classification
- 14. Allen and Ferguson Classification • First mechanistic classification for the subaxial cervical spine • 6 mechanisms of injury • Compression flexion • Vertical compression • Distraction flexion • Compression extension • Distraction extension • Lateral flexion
- 16. Allen and Ferguson Classification
- 17. Harris Classification • Published in 1986. • 7 mechanisms of injury • Flexion (5 subgroups) • Flexion rotation • Extension-rotation • Vertical compression (2 subgroups) • Hyperextension (7 subgroups) • Lateral flexion • Diverse / Imprecisely understood mechanisms (2 subgroups)
- 18. Cervical Spine Injury Severity Score (CSISS) • Published in 2006 by Moore. • Based on the four-column model • Anterior + Posterior + Left + Right Pillars • Scoring system from 0-5 in each of the four columns, depending on severity.
- 19. Cervical Spine Injury Severity Score (CSISS) Score: <5: Non operative 5 – 7: Grey >7: Surgical
- 20. Subaxial Cervical Spine Injury Classification (SLIC) • Published in 2007 by Vaccaro et al. • 3 components • Injury morphology • Disco-ligamentous complex (DLC) • Neurological status
- 21. Subaxial Cervical Spine Injury Classification (SLIC)
- 22. Injury Morphology • Compression injury • A visible loss of height through part of an entire vertebral body, or disruption through an endplate. • Distraction injury • Includes both flexion and extension injury • Evidence of anatomic dissociation in the vertical axis • Rotation/translation injury, • There must be “horizontal displacement of 1 part of the subaxial cervical spine with respect to the other”
- 23. DLC • Abnormal widening of the anterior disc space • Abnormal facet alignment • High signal intensity seen horizontally through a disc involving the nucleus and anulus on a T2 sagittal MRI • Widening of the space between 2 spinous processes • Increased water content as seen on T2-weighted MRI and interpreted as a sign of oedema should be classified as indeterminate
- 24. Neurological Status • An important indicator of the severity of spinal column injury • Significant neurological injury infers a significant force of impact and potential instability to the cervical spine • Neurological status may be the single most influential predictor of treatment
- 25. AO Spine Classification • AOSpine Knowledge Forum developed the spinal trauma classification in 2013 • 3 major types • A: Compression injuries • B: Tension band injuries • C: Translation injuries • F: Facet injuries
- 26. Type A – Compression Injuries
- 27. Type B – Tension Band Injuries
- 28. Type C – Translation Injuries
- 29. Type F – Facet Injuries
- 32. White and Panjabi Spinal Stability
- 33. References • Allen BL Jr, Ferguson RL, et al. A mechanistic classification of closed, indirect fractures and dislocations of the lower cervical spine. Spine (Phila Pa 1976). 1982 Jan-Feb;7(1):1-27. • Harris JH, Edeiken-Monroe B, Kopaniky DR. A practical classification of acute cervical spine injuries. The Orthopedic clinics of North America. 1986 Jan;17(1):15–30. • Moore T a, Vaccaro AR, Anderson P a. Classification of lower cervical spine injuries. Spine. 2006 May 15;31(11 Suppl):S37–43 • Vaccaro AR, Hulbert RJ, Patel A a, Fisher C, Dvorak M, Lehman R a, et al. The subaxial cervical spine injury classification system: a novel approach to recognize the importance of morphology, neurology, and integrity of the disco-ligamentous complex. Spine. 2007 Oct 1;32(21):2365–74 • Vaccaro AR, Koerner JD, Radcliff KE, et al. AOSpine subaxial cervical spine injury classification system. Eur Spine J. 2016;25:2173–2184. doi:10.1007/s00586-015-3831-3 • White AA, Panjabi MM. The Problem of Clinical Instability in the Human Spine: A Systematic Approach. In: Clinical Biomechanics of the Spine. 2nd ed. Philadelphia: J.B. Lippincott; 1990:277– 378
- 34. Thank you
Editor's Notes
- Mostly mechanistic based, whereas SLIC is not mechanism based and incorporates the neurological function and modifiers. OCNA – Orthopedic Clinic of North America
- The first mechanistic classification for the subaxial cervical spine was developed by Allen and Ferguson in which they described cervical fractures and dislocations based on 6 mechanisms of injury. They hypothesise that the mechanism that causes an injury can be deduced from the radiographical findings, that similar injuries are caused by similar injury mechanisms and that within each injury class “there is a spectrum of injury which ranges from trivial to severe. They classify each injury into a subgroup (stage) based on radiographic pathology.
- In 1986, Harris et al published “A Practical Classification of Acute Cervical Spine Injuries.
- Evidence of anatomic dissociation in the vertical axis”, i.e. with a partial or complete disruption of either or both of the anterior ligamentous complex and the posterior ligamentous complex.
- The disco-ligamentous complex consists of the anterior and posterior longitudinal ligaments, the intervertebral disc, the facet capsules, interspinous and supraspinous ligaments, and the ligamentum flavum, i.e. both the anterior ligamentous complex and the posterior ligamentous complex.
- Neurological status is included in the classification because it is “an important indicator of the severity of spinal column injury” and “significant neurological injury infers a significant force of impact and potential instability to the cervical spine. The authors postulate that “neurological status may be the single most influential predictor of treatment.
- The definition of stability from White and Panjabi that we are all familiar with - the ability of the spine under physiologic loads to limit displacement so as to prevent injury or irritation of the spinal cord and nerve roots (including cauda equina), and to prevent incapacitating deformity or pain due to structural changes. In general, all else being equal, compromise of anterior elements produces more instability in extension, whereas compromise of the posterior elements produces more instability in flexion (important in patient transfers and immobilization). If there is inadequate information for any item, add half of the value for that item to the total. Stretch test: apply incremental cervical traction loads of 10 lbs q 5 mins up to 33% body wt. (65 lbs max). Check X-ray and neuro exam after each change. Positive if increase in separation > 1.7 mm or increase angulation > 7.5° on X-ray or change in neuro exam. This test is contraindicated if obvious instability. Pavlov ratio = the ratio of (distance from the midlevel of the posterior VB to the closest point on the spinolaminar line): (the AP diameter of the middle of the VB) Dangerous loading e.g., heavy laborers, contact sports athletes, motorcyclists