Spinal Trauma Imaging Approach to Diagnosis Part II
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Table of Contents
Hyperextension Injury
Hangman’s Fx aka traumatic spondylolisthesis of C2 with a fracture of pars interarticularis or pedicles (unstable)
MVA is the most common cause
Mechanism: acute hyperextension of upper C/S similar to judicial hanging (never actually seen and most deaths are due to asphyxiation)
Secondary flexion may tear PLL and disc
Associated injuries: 30% have other c-spine fx especially Extension teardrop at C2 or C3 due to avulsion by ALL
Cord paralysis may only present in 25% due to bony fragments dissociation and canal widening
Hangman fx and extension teardrop
Cervical degeneration and previous fusion is a key predisposing factor due to the lack of mobility and suppleness, rendering C/S easy to fracture
Imaging: initial x-radiography then CT that helps to delineate another injury such as facet/pedicle Fx further. MRI may help if complicated by Vertebral A. damage
Management: if type 1 injury then closed reduction and rigid collar for 4-6 weeks, halo bracing if type 2 (>3-5mm displacement) Fx/instability, anterior or posterior spinal fusion at C2-3 if type 3 Fx (>5-mm displacement)
Extension teardrop Fx (stable) potentially unstable if put in extension
Avulsion of an inferior anterior body by ALL. More seen in elderly with superimposed C/S spondylosis
Key radiography: a smaller anterior-inferior body corner, no disruption of ligamentous alignment. Typically at C2 or C3 due to sudden hyperextension and ALL avulsion
Complication: central cord syndrome (m/c incomplete cord injury) esp. in superimposed spondylosis and canal stenosis by the laxity of ligamentum flavum and osteophytes
Management: hard collar isolation
Vertical (axial) Compression Injury
Jefferson Fx (named after British neurosurgeon who defined it) (unstable but neurologically intact Fx) 7% of all C/S injuries. Stability is dependent if the transverse ligament is intact or torn, which can be noted by overhanging of C1 lateral masses over C2 >5-mm combined (left image)
Mechanism: C1 compression (e.g., diving into shallow waters) causing burst Fx-classically 4-parts of the anterior and posterior arch of C1. Variations exist.
Complications: 50% show other C/S Fx, 40% show Odontoid C2 Fx esp. if extension and axial loading occur
Imaging: x-radiography followed by CT scanning to evaluate subaxial injury and complexity of C1 injury. Note Jefferson Fx with pillar and transverse foramina fx requiring posterior occipital-cervical fusion (below right image).
Management: rigid collar immobilization if the transverse ligament is intact. Halo brace or fusion if the transverse ligament is ruptured
Cervical Injuries With Variable Mechanisms of Trauma
Odontoid process fractures:
These occur with a variety of mechanisms, flexion, extension, lateral flexion. Elderly with superimposed spondylosis are at higher risk.
Anderson & D’Alonzo classification (below). Type 2 is the most common and most unstable. Type 3 has the best chance of healing d/t more massive bleed into C2 body and better healing potential.
Imaging: x-radiography can miss some Fx. CT scanning is essential.
On x-radiography note tilting of the Dens on lateral and APOM views. CT will reveal the injury and classify it.
Complications: cord injury, non-union
CT scanning: type 2 odontoid fracture (unstable)
Management: type 1 (alar ligament avulsion) most stable observed and treated with rigid collar.
In young patients, Halo brace is used to treat type 2
Older patients do not tolerate Halo
Operative C1-2 fusion if unstable is Dx and cord signs or other complicating factors are present
Normal Radiographic Variants & Anomalies Simulating Pathology
Pediatric spine appears different especially in children younger than 10-years old.
Normal variations; ADI 5-mm and may increase or decrease on flexed/extended views by 1-2-mm
C2-3 may appear as pseudo-subluxation due to normal ligamentous laxity in children (below arrow)
Pediatric vertebral bodies usually are narrower and anteriorly wedged due to the presence of cartilaginous tissue
APOM view appears different in children, and some asymmetry of C1 articular masses is normal (below top image) and should not be confused with Jefferson Fx
In adults, any asymmetry or “overhanging” of C1 articular masses is pathological and may indicate Jefferson fx
Standard ossification centers of the Atlas synchondrosis in children should not be mistaken for fractures
Persistent ossiculum terminal of Bergman is a typical variant/anomaly of tenacious un-united ossification center and should not be confused with type odontoid fx
Os odontoideum
Un-united growth center that currently considered as an un-noticed injury that disturbed normal growth in a child younger than 5-years-old
It may be a cause of C1-2 instability and should be evaluated with flexed and extended cervical views
Should not be confused with type 2 Dens fracture because it typically more demonstrates greater mineralization of bone
Incomplete bilateral agenesis of the C1 posterior arch
Anomalous closure of C1 posterior arch
Should not be confused with a fracture
However, local or cord symptoms may develop after trauma in some cases
Relatively rare anomaly developing due to failed chondrogenesis and ossification of posterior ossification centers of the Atlas
Patients with Down syndrome may suffer from increased ligamentous laxity and other abnormalities
Increased risk of subluxation at C1-2
Burst Fx (unstable) 2-columns are damaged
Mechanism: axial loading with frequent flexion after falls and MVAs
The thoracolumbar region is the most vulnerable due to the increased fulcrum of motion
Key radiography: acute compression fracture and collapse of body height, retropulsion of posterior body and acute kyphotic deformity on the lateral view
On the frontal view: interpedicular widening (below yellow arrow), regional soft tissue swelling (below green arrow)
Imaging: x-radiography should be followed by CT scanning w/o contrast
MRI if neurologically unstable due to cord or conus injury
Complications: cord damage by acutely retropulsed bone fragments
Management: non-operative if neurologically intact and <50% body retropulsed with minimal kyphosis
Operative (fusion) if 50% or more body retropulsed, laminar/pedicle Fx, neuro compromised
18-Year Old Female Following Trampoline Accident
AP & lateral L/S views
Note acute compression fracture, a vertebral body extending to posterior elements
Widening of the inter-spinous distance between T11-T12 (below arrow)
Radiolucent fracture line is seen through the T12 body on the AP projection
CT scanning was performed
Sagittal reconstructed Thoracic and Lumbar CT slices in bone window
Note acute compression fracture, the T12 body extending into pedicle and lamin
Dx: Chance fracture of T12
MR imaging was performed
T2 Wl sagittal MRI
Findings: acute compression fracture T12 body extending to posterior elements causing rapture of interspinous and flavum ligaments
Mild compression of the distal cord above the conus is noted with a minimal signal abnormality
Dx: Chance fracture
Chance Fx aka (Seatbelt Fx) – is a flexion-distraction injury (unstable)
M/C in lower thoracic-upper lumbar
All 3-columns fail: column 3 torn by distraction, columns 1 and 2 fail on compression (Denis classification)
Causes: MVA, falls
Imaging: initial x-radiography should be followed by CT scanning w/o contrast to assess bone fragments retropulsion/canal compression. MRI may help to evaluate potential cord damage and ligaments tearing
Management: non-operative immobilization if neuro intact