Daniel S. Chow, MD Jason Talbott, MD Mechanism Based Approaches to Identifications of Traumatic Spine Injury Daniel S. Chow, MD Jason Talbott, MD

Disclosures The authors have no conflicting financial disclosures.

Content Organization Background Overview of Classifications Examples by Mechanism Post Quiz

Background Epidemiology of spine trauma within the US: Incidence: 12,500 Prevalence: 240,000 to 337,000 Mean age: 42 years Impact on patients & society: Incomplete tetra- and paraplegia make up 66% of outcomes Lifetime cost is variable, but mean yearly expense is estimated at $71,961 per patient National Spinal Cord Injury Statistical Center, Facts and Figures at a Glance. Birmingham, AL: University of Alabama at Birmingham, 2015.

Overview of Spine Trauma Classification Watson & Jones (1938) Holdsworth (1963) AO (1994) 1920 1940 1960 1980 2000 Böhler (1932) Nicoll (1949) Denis & McAfee (1983) TLICS (2005) 1930 - Böhler 1962 – Holdsworth 1983 – Denis & mcafee 1994- AO 2005 TLICS Classification allow for uniform description of injury. Over time, classification of spine injury can broadly be divided into anatomic changes and mechanism of injury.

Title page from Watson & Jones 1938 article Overview of Spine Trauma Classification Böhler, Watson/Jones, and Nicoll 1930 – 1949 Böhler (1930) described five categories of injury based on mechanism of injury. However, this classification did attempt to identify instability. Compression Shear Flexion – Distraction Rotational Extension Watson & Jones (1938) evaluated a series of 252 radiographs. Built on Böhler’s study and added: Concept of instability and influence on treatment Importance of the posterior longitudinal ligament for stability Böhler2 initially attempted to classify thoracolumbar spine fractures using five injury types. He combined both anatomic appearance and mechanisms of injury to include compression fractures, flexion-distraction injuries, extension fractures, shear fractures, and rotational injuries in his classification scheme. Böhler, however, did not attempt to define instability patterns based on the anatomical appearance of the injury. Nicoll (1949) evaluated a series of 152 radiographs. Built on prior studies and described an anatomic based classification, stressing the importance of the vertebral body, disc, intervertebral joint, and interspinous ligament. Title page from Watson & Jones 1938 article

Overview of Spine Trauma Classification Holdsworth 1962 Holdsworth (1962) introduces new classification scheme based on two column model in a review of over 1000 patients who suffered traumatic paraplegia. Stressed the importance of the posterior longitudinal ligament. Böhler2 initially attempted to classify thoracolumbar spine fractures using five injury types. He combined both anatomic appearance and mechanisms of injury to include compression fractures, flexion-distraction injuries, extension fractures, shear fractures, and rotational injuries in his classification scheme. Böhler, however, did not attempt to define instability patterns based on the anatomical appearance of the injury. Anterior Ant. longitudinal ligament Vertebral body Intervertebral disc Post. longitudinal ligament Posterior Posterior joint Interspinous ligament Supraspinous ligament Anterior Posterior

Overview of Spine Trauma Classification Denis & McAfee 1983 In 1983, Francis Denis introduces a 3-column approach Based on retrospective review of 412 fractures. Combination of both mechanism of injury and anatomy. Compression (4 types) Burst (5 types) Seat Belt (4 types) Fracture – Dislocation (3 types) In 1983, McAfee also describes a 3-column model in 100 patients and also stresses the importance of the middle column. Anterior Posterior Denis F. The three column spine and its significance in the classification of acute thoracolumbar spinal injuries. Spine (Phila Pa 1976). 1983 Nov-Dec;8(8):817-31. Baker AD. Classic Papers in Orthopaedics (2013). The Three Column Spine and Its Significance in the Classification of Acute Thoracolumbar Spinal Injuries. pp 289-292 Anterior Middle Posterior

Overview of Spine Trauma Classification Denis & McAfee 1983 Pros Easy to understand conceptually Most frequently cited (and probably still most frequently used) Cons Does not account for patient clinical status Does not take into account of ligamentous support, which limits accurate assessment of stability. Con: stable vs unstable can be confusion? Anterior Ant. Longitudinal Ligament Ant. Annulus Ant. 2/3 Vertebral body Middle Post. Longitudinal Ligament Post. Annulus Post. 2/3 Vertebral body Posterior Posterior bony elements (pedicles, lamina, spinous process) Posterior ligaments Anterior Middle Posterior

Overview of Spine Trauma Classification Magerl Classification 1994 Magerl (1994) introduces new classification scheme based on mechanism on injury and two column model in a review of over 1400 patients. Three types BUT over 50 subtypes (see following slide). Compression Flexion-Extension Rotational Review of 1445 cases 3 types with over 50 patterns Very detailed ; however, very complex and not practically reproducible Very poor reproducibility interobserver Pros Very detailed Considers both fracture pattern and mechanism Cons Overly complex Poor reproducibility Does not account for clinical status

Overview of Spine Trauma Classification Magerl – AO Classification 1994 Type A. Vertebral body compression A1 (Impaction fractures) A1.1 Endplate impaction A1.2 Wedge impact (3) A1.3 Vertebral body collapse A2 (Split fractures) A2.1 Sagittal split A2.2 Coronal split A2.3 Pincer A3 (Burst fractures) A3.1 Incomplete (3) A3.2 Burst-split (3) A3.3 Complete (3) Type B. Ant & Post Element Injury B1 Posterior disruption predominantly ligamentous (Flexion-distraction) B1.1 with disruption of disc (3) B1.2 with type A fracture (3) B2 Posterior disruption predominantly osseus (Flexion-distraction) B2.1 Transverse bicolumn B2.2 With disruption of disc (2) B2.3 With type A fracture (2) B3 Ant disc disruption (Hyperextension) B3.1 with subluxation (2) B3.2 with spondylolysis B3.3 with posterior dislocation Type C. Ant & Post Element with rotation C1 Type A with rotation C1.1 Rotational wedge C1.2 Rotation split (4) C1.3 Rotational burst (3) C2 Type B with rotation C2.1 B1 with rotation (7) C2.2 B2 with rotation (3) C2.3 B3 with rotation (3) C3 Rotational - Shear C3.1 Slice fracture C3.2 Oblique fracutre * () indicate number of subtpes Magerl F. A comprehensive classification of thoracic and lumbar injuries. Eur Spine J. 1994;3(4):184-201.

Overview of Spine Trauma Classification TLICS 2005 Spine Trauma Study Group (2005) introduces Thoracolumbar Injury Classification Score, which assigns points based on: Fracture Mechanism Compression 1 Burst 2 Rotational 3 Distraction 4 Neurologic Involvement Intact 0 Nerve root 2 Cord & Conus Complete 2 Incomplete 3 Conus 3 Posterior Ligament Complex Intact 0 Indeterminate 2 Injured 3 Conservative < 4 points 4 points: Indeterminate > 4 points - Operate

Overview of Spine Trauma Classification AOSpine TLICS Classification 2013 AO Spine TLICS Classification TLICS AO (Magerl) The reproducibility and feasibility of evaluating PLC integrity using magnetic resonance imaging (MRI) has been questioned.13,14 Also, the chosen severity scoring system guiding treatment may be a culture- or region-specific decision and may not reflect global surgical preferences or the most rational approach to treatment. The AOSpine Trauma Knowledge Forum, an international group of academic spine surgeons, was tasked to develop and validate a classification system incorporating both fracture morphology and clinical factors relevant for surgical decision making, such as the presence of neurological deficits. The goal of this effort was to develop a widely accepted, comprehen- sive yet simple classification system with clinically acceptable intra- and interobserver reliability to be used for clinical prac- tice and research purposes. agerl classification using an AOSpine database of more than 750 spinal trauma case In 2013 the AO Spine Trauma Knowledge Forum combined TLICS with a revised Magerl classification to produce a comprehensive and simple classification scheme

Overview of Spine Trauma Classification AOSpine TLICS Classification 2013 Type A. Vertebral body compression A1 Single Endplate A2 Pincer A3 Incomplete Burst (Single endplate + Posterior wall) A4 Complete Burst (Both endplates + Posterior wall) Type B. Failure of the posterior or anterior tension band B1 Posterior Osseus Tension Band B2 Posterior Ligamentous Tension Band B3 Anterior Tension Band Type C. Distraction, leading to failure of all elements leading to dislocation or displacement in any plane There are no subtypes Clinical Status N0 Neurologically intact N1 Transient neurological deficit N2 Symptoms or signs of radiculopathy N3 Incomplete spinal cord injury or cauda equina injury N4 Complete spinal cord injury

Examples by mechanism Mechanism of injury describes the mechanical mode of failure. Benefits: Knowing mechanism may help classify Limitations of mechanisms: Does not alone determine stability Exact mechanism may sometimes be unknown

Examples Axial loading with Flexion (Compression) Axial loading with flexion generally leads to compression injury (Type A fractures) Most common type, accounting for up to 90% of cases. The anterior column is compressed, with variable involvement of the remaining middle and posterior column Compression: Axial loading + Flexion Patient 1: 26 year old female in MVA. Sagittal CT demonstrates an anterior compression fracture at T3.

Examples Axial loading with Flexion (Compression) Patient 2 Sagittal T2 of the thoracic spine demonstrates a compression fracture with single endplate involvement. A1: Single endplate (Green Arrow) B0: Tension bands Intact (Curved Arrow) C0: No Distraction (White arrowhead) Compression: Axial loading + Flexion

Examples Axial loading with Flexion (Compression) Patient 3: Sagittal CT of the thoracic spine demonstrates a compression fracture with single endplate involvement. A1: Single endplate (Green arrows) Patient 3 Sagittal T2 of the thoracic spine demonstrates a compression fracture with single endplate involvement as well as disruption to the posterior band. A1: Single endplate (Green arrows) B2: Disruption of posterior tension band (Curved yellow line) C0: No Distraction (Red lines) Compression usually from axial + flexion However, not all compression fractures are created equal.

Examples Compression with Axial loading (Burst) Patient 4: Axial and sagittal CT of the thoracic spine demonstrates an incomplete burst fracture (only superior endplate involved), A3 Axial compression generally leads to a burst injury, which may be incomplete (A3) or complete (A4). Typically high energy trauma (i.e. fall from height) Most commonly at the thoracolumbar junction and between T5 through T8.

Examples Compression with Axial loading (Burst) Patient 5: Axial and Sagittal CT of the thoracic spine demonstrates a complete burst fracture, involving both endplates as well as the posterior wall. A4: Complete Burst Fracture

Examples Compression with Axial loading (Burst) * Patient 5 Sagittal T2 of the thoracic spine demonstrates a compression fracture with both endplates involved. A4: Both superior and inferior endplate involvement B0: Tension bands Intact (Curved Arrow) C0: No Distraction

Examples Compression with Axial loading (Burst) * Historically, the Denis classification would consider this a two column injury (anterior and middle), which is unstable. However, MRI reveals that the posterior and anterior tensor bands are maintained

Examples Distraction Patient 6: Sagittal CT and MR reveals complete failure of all elements leading to Displacement (Type C injury) Distraction results from separation of the adjacent vertebral bodies. High chance of cord injury once supporting structures (osseous and ligamentous) are pulled separated. While the appearance may be variable, there is no subtype A distraction injury is separation or pulling apart of two adjacent vertebrae. It is a severe injury since there is a high chance of cord injury when its osseous and ligamentous supporting structures are pulled apart.

Examples Distraction Patient 7 Sagittal T2 demonstrates complete separation between the thoracic vertebral bodies and ligamentous structures. A0: No compression deformity B: Anterior and Posterior tensor bands are disrupted C: Traumatic anterolisthesis 29 year MVA

Post Quiz #1 Which of the following is true regarding this injury? The most common type of compression deformity Results from vertical separation Universally unstable Most commonly located at the thoracolumbar junction

Post Quiz #1 Which of the following is true regarding this injury? The most common type of compression deformity Results from vertical separation Universally unstable Most commonly located at the thoracolumbar junction Explanation: Depicted is a burst fracture, which is most commonly located at the thoracolumbar junction (Choice D). Briefly, single endplate compression fractures are the most common (Choice A). Distraction injuries arise from separation (Choice B). Lastly, not all burst fractures are unstable (Choice C).

Post Quiz #2 Which of the following is true regarding this injury? There are multiple subtypes given variability of this injury. High likelihood of cord injury. Results from axial loading. Can often be managed conservatively. Explanation: Depicted is a distraction injury fracture, which is commonly associated with cord injury (Choice B). Briefly, while there is high variability, these are all considered Type C and there is no subtype. Distraction injuries arise from separation (Choice B). Lastly, distraction injuries are generally unstable (Choice D).

References Bohler L. Die techniek de knochenbruchbehandlung imgrieden und im kriege. Verlag von Wilhelm Maudrich 1930 (in German) Watson - JonesS. The results of postural reduction of fractures of the spine. J Bone Joint Surg Am, 1938 Jul; 20 (3): 567 -586 NICOLL EA. Fractures of the dorso-lumbar spine. J Bone Joint Surg Br. 1949 Aug;31B(3):376-94. Holdsworth F. Fractures, dislocations, and fracture-dislocations of the spine. J Bone Joint Surg Am. 1970 Dec;52(8):1534-51. Denis F. The three column spine and its significance in the classification of acute thoracolumbar spinal injuries. Spine (Phila Pa 1976). 1983 Nov-Dec;8(8):817-31. Baker AD. Classic Papers in Orthopaedics (2013). The Three Column Spine and Its Significance in the Classification of Acute Thoracolumbar Spinal Injuries. pp 289-292 Magerl F. A comprehensive classification of thoracic and lumbar injuries. Eur Spine J. 1994;3(4):184-201. Parizel PM, van der Zijden T, Gaudino S, et al. Trauma of the spine and spinal cord: imaging strategies. Eur Spine J. 2010 Mar;19 Suppl 1:S8-17. Using the popular Denis three-column classification may lead to another situation since it uses the terms stable and unstable. In many cases, however, there is no good correlation with the necessity for surgery.