Classification of Thoracolumbar Spine Injuries

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Classification of Thoracolumbar Spine Injuries

• Jim A. Youssef, MD
• Original Authors Christopher Bono, MD and Mitch
  Harris, MD March 2004
• New Author Jim A. Youssef, MD Revised January
  2006

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Historical Classification Systems
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More Commonly Used Classification Systems
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Denis Three-column model

• Anterior column- formed by the anterior
  longitudinal ligament, the anterior annulus, and
  the anterior portion of the vertebral body
• Middle osteoligamentous- the critical feature.
  Very important to spinal stability consists of
  posterior longitudinal ligament, the posterior
  portion of the annulus, and the posterior aspect
  of the vertebral body
• Posterior column- includes the neural arch, facet
  joints and capsules, ligamentum flavum, and
  remaining ligamentious complex

Denis F. Clin Orthop Relat Res. 1984
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Denis Middle-column concept

• Developed to define burst fracture
• Middle column has limited value for biomechanical
  stability modeling

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History- Denis

• Studies have supported the three-column theory
  and found that the middle column is the primary
  determinant of mechanical stability of the
  thoracolumbar region of the spine.

Panjabi, MM. Spine, 1995.
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History- Gertzbein

• Other classification systems developed
  concurrently, most focusing on flexion-distraction
  injuries
• Gertzbein et al. suggests classification into
  three separate portions
• Posterior component
• Anterior component
• Body component

Gertzbein SD, Court-Brown CM Flexion-Distraction
Injuries of the Lumbar Spine. Clin Orth 1988
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History- Gertzbein

• The relative proportion of disc and ligamentous
  involvement compared to bony involvement predicts
  the probability that the injury will heal without
  surgical involvement
• Involvement of the vertebrae is important as it
  might relate to bony collapse and thus kyphosis

Gertzbein SD, Court-Brown CM Flexion-Distraction
Injuries of the Lumbar Spine. Clin Orth 1988
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McAfee and Associates

• Based on the CT scan appearance of 100 fractures
• Six injury patterns
• Wedge-compression fracture
• Stable burst
• Unstable burst
• Chance
• Flexion-distraction
• Translational

McAfee PC, Yuan HA, et al. The value of CT in
thoracolumbar fractures. JBJS 1993
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Classification

• Compression Fracture

McAfee PC, Yuan HA, et al. The value of CT in
thoracolumbar fractures. JBJS 1993
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Classification

• Stable Burst Fracture

• Minimal Kyphosis
• lt 50 Ht. Loss
• Moderate CC
• No Neuro Deficit
• No Posterior Inj.

McAfee PC, Yuan HA, et al. The value of CT in
thoracolumbar fractures. JBJS 1993
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Classification

• Unstable Burst Fracture

• Posterior element disruption
• Progressive neurological deficit
• Kyphosis of greater than 20º-30º
• Anterior height loss gt 50
• Canal compromise gt 50

McAfee PC, Yuan HA, et al. The value of CT in
thoracolumbar fractures. JBJS 1993
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Classification

• Flexion - Distraction Injury

McAfee PC, Yuan HA, et al. The value of CT in
thoracolumbar fractures. JBJS 1993
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Classification

• Translational Shear Injury

McAfee PC, Yuan HA, et al. The value of CT in
thoracolumbar fractures. JBJS 1993
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Ferguson and Allen

• Combines the work of Denis and McAfee and et al.
• Uses a mechanistic classification to clarify the
  patterns of thoracolumbar spine injury
• Hypothesizes that most injuries were the result
  of
• Compression
• Tension
• Torsion
• Translational forces

Nicole EA Fractures of the dorsolumbar spine. J
Bone Joint Surg Br 31376-394, 1949
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Ferguson and Allen

• Treatment is linked to injury patterns and an
  attempt was made to match the type of
  instrumentation to the type of injury
• System proved to be cumbersome and non-specific
  for everyday use

Nicole EA Fractures of the dorsolumbar spine. J
Bone Joint Surg Br 31376-394, 1949
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Gaines Load Sharing Classification

• Created system in response to poor patient
  outcomes when the vertebral body sustained a
  disproportionately severe injury
• Classification system grades
• Amount of damaged vertebral body
• Spread of the fragments in the fracture sight
• Amount of corrected kyphosis

McCormack et al. Spine, 1994
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Gaines Load Sharing Classification

• Load-Sharing Classification a straight-forward
  way to describe the amount of bony comminution in
  a spinal fracture
• Can help the surgeon select short-segment
  pedicle-screw-based fixation using the posterior
  approach for less comminuted injuries and the
  anterior approach for those more comminuted
  injuries if the patient meets the following
  criteria
• Isolated spine fracture
• Compliant with 3 to 4 months of spinal bracing

Parker et al, Spine, 2000
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Gaines Load Sharing Classification

• System can be used pre-operatively to
• Predict screw breakage when short segment,
  posteriorly placed pedicle screw implants are
  being used
• Describe any spinal injury for retrospective
  studies
• Select spinal fractures for anterior
  reconstruction with strut graft

McCormack et al. Spine, 1994
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Gaines Load Sharing Classification

• Inter-observer and intra-observer reliability of
  the Load Sharing system was evaluated by 5
  observes on 2 occasions.
• Analysis found high levels of agreement when Load
  Sharing Classification was used to assess
  thoracolumbar burst fractures.
• Dai and Jin (2005) concluded that the system
  could be applied with excellent reliability.

Dai LY, Jin WJ. Spine, 2005.
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AO Classification

• Based on the review of 1445 consecutive
  thoracolumbar injuries
• Primarily based on pathomorphological criteria
• Categories based on
• Main mechanism of injury
• Pathomorphological uniformity
• Prognostic aspects regarding healing potential

Magerl et al. Eur Spine J. 1994.
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AO Classification

• Classification reflects progressive scale of
  morphological damage by which the degree of
  instability is determined
• Consists of a 3-3-3 grid for sub-grouping
  injuries into three types
• A, B and C
• Every type has three groups, each of which
  contains three subgroups with specifications

Magerl et al. Eur Spine J. 1994.
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AO Classification

• Types have a fundamental injury pattern which is
  determined by the three most important mechanisms
  acting on the spine
• Compression
• Distraction
• Axial torque

Magerl et al. Eur Spine J. 1994.
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AO Classification - A, B, Cs

• Type A
• Vertebral body compression- injury patterns of
  the vertebral body
• Type B
• Anterior and posterior element injuries with
  distraction, characterized by transverse
  disruption either anteriorly or posteriorly
• Type C
• Anterior and posterior injuries with rotation,
  injury patters resulting from axial torque

Magerl et al. Eur Spine J. 1994.
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Examples of AO Classification
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AO Classification

• Superior incomplete
• Burst fracture
• A3.1.1

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AO Classification

• Flexion-subluxation
• B1.1.1

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AO Classification

• Rotational shear injury
• C3.2

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Determination of Thoracolumbar Instability
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Reproducibility studies

• Blauth el al Mean inter-observer reliability
  67 when 22 hospitals evaluated 14 radiographs
  and CT scans
• Wood, Vaccaro, et al Only moderate
  reproducibility and repeatability among
  well-trained spine surgeons using AO and Denis
  classification systems

Orthopade, 1999 NASS, 2004
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Summary

• Currently no classification system that has
  achieved global clinical utility and acceptance
• Few studies evaluating the effectiveness of the
  different systems studies which have been
  conducted use small samples sizes

Gotzen L, et al. Unfallchirurg, 1994.
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