EuroSpine 2014

Research/KF Trauma

Cumhur Oner, MD

Pre-Validation Process of the AO Subaxial Cervical Spine Classification System AR Vaccaro, KE Radcliff, CK Kepler, JD Koerner, F Kandziora, KJ Schnake, LR Vialle, FC Oner, MF Dvorak, B Aarabi, MG Fehlings, S Rajasekaran, M Reinhold

University Medical Center,

Utrecht, Netherlands

Lyon, France

October 1-3, 2014

Research/KF Trauma 2

Background

Objective To create and test a pre-validation process for the development

of a new classification system.

To determine if areas of disagreement can be identified before

validation

Many classifications for subaxial cervical spine trauma: none

have been widely accepted.

AOSpine TL Classification System

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Material and Methods

AOSpine Classification group – development of a morphology

based classification system:

Seven face -to-face meetings

Numerous teleconferences

Ten sample cases representative of various injuries were sent for

scoring. Two authors reviewed the responses (consensus on gold

standard).

Incorrect responses were returned to each member

Ability to identify trends of consistent areas of disagreement

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Seven of ten cases had perfect agreement

Three consistent areas of disagreement identified:

Differentiating flexion distraction from compression type injuries

Identifying displacement of facets and facet subluxation versus

perched versus dislocated.

Patient specific modifiers.

Modification of the classification system

Results

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Distraction Injuries (B-type):

Adjusted descriptions of the subtypes (B1, B2, and B3)

Facet Injuries:

Clarification regarding nondisplaced (F1) and displaced (F2)

Merging of three subtypes (subluxation w/o facet fracture,

perched facet , and dislocated facet) into one subtype (F4)

Modifiers

Adjusted description for one modifier

Deletion of two modifiers

Modifications

Morphology: Types

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Type A injuries

Failure of anterior structures under compression with intact tension band

Type B injuries

Failure of the tension band

Type C injuries

Failure of anterior and posterior elements leading to displacement

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Compression Injuries (A)

Subtype Description

AO No bony injury or minor injury

such as an isolated lamina

fracture or spinous process

fracture

A1 Compression fracture involving a

single endplate without

involvement of the posterior wall

of the vertebral body

A2 Coronal split or pincer fracture

involving both endplates without

involvement of the posterior wall

of the vertebral body

A3 Burst fracture involving a single

endplate with involvement of the

posterior vertebral wall

A4 Burst fracture or sagittal split

involving both endplates

Distraction Injuries (B)

Subtype Description

B1 Physical separation

through fractured bony

structures only

B2 Complete disruption of the

posterior

capsuloligamentous or

bony capsuloligamentous

structures together with a

vertebral body, disk,

and/or facet injury.

Combine with Type A

fractures

B3 Physical disruption or

separation of the anterior

structures (bone/disk) with

tethering of the posterior

elements

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Translational Injuries (C)

Translation / dislocation in any axis – displacement of translation of one

vertebral body relative to another in any direction.

Facet Injuries (F)

Type Subtype

F1 Nondisplaced Facet Fracture with fragment <1cm in

height, <40% of lateral mass

F2 Facet fracture with fragment >1cm, > than 40%

lateral mass, or displaced

F3 Floating lateral mass

F4 Pathologic subluxation or perched/dislocated facet

BL Bilateral injury

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Neurology Modifiers (M)

Type Description

M1 Posterior Capsuloligamentous Complex

injury without complete disruption

M2 Critical disk herniation

M3 Stiffening/metabolic bone disease (ie

DISH, AS, OPLL, OLF)

M4 Vertebral artery abnormality

Type Subtype

N0 Neurologically intact

N1 Transient neurologic deficit

N2 Radiculopathy

N3 Incomplete spinal cord injury

N4 Complete spinal cord injury

NX Neurological status unknown

+ Ongoing cord compression in setting of

incomplete neurologic deficit or nerve

injury

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It is possible to identify areas of disagreement

Raters need a thorough understanding of the classification system

This last point may lead to a higher interobserver and

intraobserver reliability

Conclusions

Frank Kandziora, MD: Consulting: DePuy Synthes and Siemens

Alexander R. Vaccaro, MD, PhD: Consulting/Independent contractor: Medtronics, Stryker Spine, Globus, Stout Medical, Gerson

Lehrman Group, Guidepoint Global, Medacorp, Innovative Surgical Design, Orthobullets, Expert Testimony. Scientific Advisory

Board/Board of Directors/Service on Committees: AO Spine, Innovative Surgical Design, Association of Collaborative Spine

Research, Spinicity. Royalties: DePuy, Medtronics, Stryker Spine, Biomet Spine, Globus, Aesculap, Thieme, Jaypee, Elseviere,

Taylor Francis. Stock/ Stock Option Ownership Interests: Replication Medica, Globus, Paradigm Spine, Stout Medical, Spine

Medica, Computational Biodynamics, Progressive Spinal Technologies, Spinology, Small Bone Innovations, Cross Current,

Syndicom, In Vivo, Flagship Surgical, Flagship Surgical, Advanced Spinal Intellectual Properties, Cytonics, Bonovo

Orthopaedics, Electrocore, Gamma Spine, Location Based Intelligence, FlowPharma, R.S.I., Rothman Institute and Related

Properties, Innovative Surgical Design, Spinicity. Institutionla/Educational Grant: Cerapedics.

Kris Radcliff, MD: Royalties: Globus Medical (A, Intellectual property, Implant Design of Cortical Pedicle Screw System);

Consulting: Globus Medical (Financial, $28,217, Consulting for Participation and Design on Globus Cortical Screw System),

Medtronic Advanced Energy (Financial, $19,000 for teaching a resident/fellow course and sales representative training related to

Aquamantys Applications), Depuy Spine (Nonfinancial, I am a member of the ProDisc Publication Committee. I have access to

ProDisc Outcome Data. No remuneration.), LDR Spine (Nonfinancial, I am participating in an independent review of the LDR

Mobi-C Disk Arthroplasty Product); Trips/Travel: AO Spine (Financial, $2000), Globus Medical (Financial, $2000), Depuy

Synthes (Financial, $2000), Stryker Spine (Financial, $158), Medtronic (Financial, $300); Board of Directors: Association for

Collaborative Spinal Research Nonfinancial, I have discretionary control over ongoing research projects and clinical reviews

including systematic reviews and guidelines including a systematic review of Low Back Pain Treatments); Grants: Depuy

Synthes (B, Grant for support of resident cadaver lab, Paid directly to institution/employer), Medtronic (B, Grant for support of

resident cadaver lab, Paid directly to institution/employer), Paradigm Spine (B, Grant for support of resident cadaver lab, Paid

directly to institution/employer).

Luiz Vialle, MD: AO Foundation Board membership

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Disclosures