AO Spine Injury Calculator

Based on AO Foundation's Spine Injury Classification Systems

Artwork: Medical art by Dr Joanna Butler.

To begin, select the site of injury from the diagram

Upper Cervical Spine

AO: Upper cervical

Select the identified injury *

$Isolated condyle fracture$ Isolated condyle fracture

Craniocervical ligamentous injury (Nondisplaced, +/- bony injury)

Craniocervical dissociation

$Isolated C1 Arch fracture$ Isolated C1 Arch fracture

C1-C2 Ligamentous injury (+/- bony injury)

Atlantoaxial instability/translation

$C2 fracture without ligamentous, tension band, discal injury$ C2 fracture without ligamentous, tension band, discal injury

C2-C3 Tension band / Ligamentous injury (+/- bony injury)

Translation of C2 vertebral body (in any plane)

How is patient's neurological status? *

Cannot be examined

Neurology intact

Transient neurologic deficit

Radicular symptoms

Incomplete spinal cord injury or any degree of cauda equina injury

Complete spinal cord injury

Continued spinal cord compression

Does any of the following apply to this injury? (optional)

Injuries at High Risk of Non- Union with Nonoperative Tx

Injury with significant potential for instability

Patient Specific Factors Affecting Tx

Vascular Injury or Abnormality Affecting Tx

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Lower Cervical Spine

AO: Lower cervical

Select the identified injury *

$Minor, nonstructural fractures (e.g. isolated lamina or spinous process fractures)$ Minor, nonstructural fractures (e.g. isolated lamina or spinous process fractures)

Wedge-compression (involving a single endplate without involvement of the posterior wall)

$Coronal split or pincer fracture involving both endplates without involvement of the posterior wall$ Coronal split or pincer fracture involving both endplates without involvement of the posterior wall

$Incomplete burst fracture, involving a single endplate with involvement of the posterior vertebral wall$ Incomplete burst fracture, involving a single endplate with involvement of the posterior vertebral wall

$Complete burst fracture or sagittal split (involving both endplates)$ Complete burst fracture or sagittal split (involving both endplates)

$Posterior tension band <strong>bony</strong> injury (Physical separation through fractured bony structures only)$ Posterior tension band bony injury (Physical separation through fractured bony structures only)

Posterior tension band <strong>ligamentous +/- bony</strong> injury (Disruption of capsuloligamentous structures together with a vertebral body, disc, and/or facet injury)

Posterior tension band ligamentous +/- bony injury (Disruption of capsuloligamentous structures together with a vertebral body, disc, and/or facet injury)

Anterior tension band injury (Physical disruption of bone/disc with tethering of the posterior elements)

Bilateral injuries

Displacement or translation in any axis

$Nondisplaced facet fracture, < 1 cm in height and < 40% of the lateral mass$ Nondisplaced facet fracture, < 1 cm in height and < 40% of the lateral mass

$Facet fracture, displaced, >1 cm in height, or >40% of the lateral mass$ Facet fracture, displaced, >1 cm in height, or >40% of the lateral mass

Floating lateral mass

Pathologic subluxation or perched/dislocated facet

How is patient's neurological status? *

Cannot be examined

Neurology intact

Transient neurologic deficit

Radicular symptoms

Incomplete spinal cord injury or any degree of cauda equina injury

Complete spinal cord injury

Continued spinal cord compression

Does any of the following apply to this injury? (optional)

Posterior Capsuloligamentous Complex injury without complete disruption.

Critical disc herniation.

Stiffening/metabolic bone disease (ie DISH, AS, OPLL, OLF).

Vertebral artery abnormality.

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Thoracolumbar Spine

AO: Thoracolumbar

Primary site of injury *

Select the identified PRIMARY injury *

$Minor, nonstructural fractures (i.e. not compromising the structural integrity of the spinal column)$ Minor, nonstructural fractures (i.e. not compromising the structural integrity of the spinal column)

Wedge-compression (a single endplate, sparing the posterior wall)

Split (both endplates, sparing the posterior wall)

Incomplete burst (single endplate + posterior wall)

Complete burst (both endplates + posterior wall)

$Chance fracture (transosseous tension band disruption)$ Chance fracture (transosseous tension band disruption)

Posterior tension band disrutpion

Hyperextension

Displacement or dislocation

How is patient's neurological status? *

Cannot be examined

Neurology intact

Transient neurologic deficit

Radicular symptoms

Incomplete spinal cord injury or any degree of cauda equina injury

Complete spinal cord injury

Continued spinal cord compression

Does any of the following apply to this injury? (optional)

Indeterminate injury to the tension band based on spinal imaging with or without MRI

Patient-specific comorbidity, which might argue either for or against surgery for patients with relative surgical indications*

* For example ankylosing spondylitis or burns affecting the skin overlying the injured spine

Are there additional injuries to the thoracolumbar spine? *

Yes

Secondary injuries

Level of secondary injury *

Select the additional injury *

Wedge-compression (a single endplate, sparing the posterior wall)

Split (both endplates, sparing the posterior wall)

Incomplete burst (single endplate + posterior wall)

Complete burst (both endplates + posterior wall)

$Chance fracture (transosseous tension band disruption)$ Chance fracture (transosseous tension band disruption)

Posterior tension band disrutpion

Hyperextension

Displacement or dislocation

Add more injuries Remove

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Sacrum

AO: Sacrum

Select the identified injury *

$Coccygeal or compression vs ligamentous avulsion fractures$ Coccygeal or compression vs ligamentous avulsion fractures

$Non-displaced transverse fractures below the S-I joint$ Non-displaced transverse fractures below the S-I joint

$Displaced transverse fractures below the S-I joint$ Displaced transverse fractures below the S-I joint

Central Fracture (involves spinal canal)

Transalar Fracture (does not involve foramina or spinal canal)

Transforaminal Fracture (involves foramina but not spinal canal)

Nondisplaced sacral U-type variant

Sacral U-type variant without posterior pelvic instability

$Bilateral vertical fractures without transverse fracture$ Bilateral vertical fractures without transverse fracture

$Displaced U-type sacral fracture$ Displaced U-type sacral fracture

How is patient's neurological status? *

Cannot be examined

Neurology intact

Transient neurologic deficit

Radicular symptoms

Incomplete spinal cord injury or any degree of cauda equina injury

Complete spinal cord injury

Continued spinal cord compression

Does any of the following apply to this injury? (optional)

Soft tissue injury

Metabolic bone disease

Anterior pelvic ring injury

Sacroiliac joint injury

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References:

AO Spine Classification Systems. AO Foundation
Lambrechts MJ, Schroeder GD, Karamian BA, et al. Global Validation of the AO Spine Upper Cervical Injury Classification: Geographic Region Affects Reliability and Reproducibility. Global Spine J. 2024;14(3):821-829. doi:10.1177/21925682221124100
Canseco JA, Schroeder GD, Paziuk TM, et al. The Subaxial Cervical AO Spine Injury Score. Global Spine J. 2022;12(6):1066-1073. doi:10.1177/2192568220974339
Lee Y, Lambrechts M, Narayanan R, et al. The Surgical Algorithm for the AO Spine Sacral Injury Classification System. Spine (Phila Pa 1976). 2024;49(3):165-173. doi:10.1097/BRS.0000000000004876
Kepler CK, Vaccaro AR, Schroeder GD, et al. The Thoracolumbar AOSpine Injury Score. Global Spine J. 2016;6(4):329-334. doi:10.1055/s-0035-1563610

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AO Spine Injury Calculator

To begin, select the site of injury from the diagram

Upper Cervical Spine

Lower Cervical Spine

Thoracolumbar Spine

Secondary injuries

Sacrum

References:

Related Calculators:

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Liver Injury Scoring Calculator

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