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Classification of Thoracolumbar Spine Injuries
Jim A. Youssef, MD
Original Authors: Christopher Bono, MD and Mitch Harris, MD; March 2004New Author: Jim A. Youssef, MD; Revised January 2006
Historical Classification Systems
System Summary CommentsNicoll Differentiates stable from
unstable fracturesServes as a foundation for subsequent classification systems
Holdsworth Modifies previous classification systems to include the mechanisms of injury and two-column theory
Fails to appreciate some burst fracture instabilities
Kelly & Whitesides Refines the two-column model Classification guides treatment of neurologic deficit
Denis Development of the three-column model
The middle column is the primary determinant of mechanical stability.
Gertzbein et al. Suggests a posterior component, anterior component and body component
Involves the vertebral body as it
relates to kyphosis.
More Commonly Used Classification Systems
System Summary Comments
McAfee Based on CT appearance; classifies injuries into 6 categories
Easily communicated type of injury with patients
Ferguson and Allen
Combines work done by Denis and McAfee; mechanistic classification to clarify patterns of thoracolumbar injury
Cumbersome, nonspecific for everyday use
Gaines Developed in response to poor patient outcomes; grades injury based on amount of damage to vertebral body, the spread of fragments in fracture site and amount of corrected kyphosis
Strong inter-observer reliability
AO Classifies types of fractures into A, B, or C and into subcategories subsequently
Moderate inter-observer reliability
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
Denis: Middle-column concept
Developed to define burst fracture
Middle column has limited value for biomechanical stability modeling
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.
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
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
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
Compression Fracture
Classification
McAfee PC, Yuan HA, et al. The value of CT in thoracolumbar fractures. JBJS 1993
Stable Burst Fracture
• Minimal Kyphosis
• < 50% Ht. Loss
• Moderate CC
• No Neuro Deficit
• No Posterior Inj.
Classification
McAfee PC, Yuan HA, et al. The value of CT in thoracolumbar fractures. JBJS 1993
Posterior element
disruption
Progressive neurological
deficit
Kyphosis of greater than
20º-30º
Anterior height loss > 50%
Canal compromise > 50%
Unstable Burst Fracture
Classification
McAfee PC, Yuan HA, et al. The value of CT in thoracolumbar fractures. JBJS 1993
Flexion - Distraction Injury
Classification
McAfee PC, Yuan HA, et al. The value of CT in thoracolumbar fractures. JBJS 1993
Translational Shear Injury
Classification
McAfee PC, Yuan HA, et al. The value of CT in thoracolumbar fractures. JBJS 1993
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 31:376-394, 1949
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 31:376-394, 1949
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
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
Gaines: Load Sharing Classification
System can be used pre-operatively to:
1. Predict screw breakage when short segment, posteriorly placed pedicle screw implants are being used
2. Describe any spinal injury for retrospective studies
3. Select spinal fractures for anterior reconstruction with strut graft
McCormack et al. Spine, 1994
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.
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.
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.
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.
AO Classification - A, B, C’s
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.
Examples of AO Classification
AO Classification
Superior incomplete Burst fracture A3.1.1
AO Classification
Flexion-subluxation
B1.1.1
AO Classification
Rotational shear injury
C3.2
Determination of Thoracolumbar Instability
Element Point Value *Anterior elements destroyed or unable to function 2Posterior elements destroyed or unable to function 2Disruption of costovertebral articulations 1Radiographic ciriteria Sagittal plane displacement >2.5mm 2 Relative sagittal plane angulation >5 degrees 2Spinal cord or cauda equina damage 2Danerous loading anticipated 1*Total of 5 or more unstable. From White AA, Panjabi MM: Clinical biomechanics of the spine, ed 4, Philadelphia, 1990, JB Lippincott.
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
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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