Thoraco-Lumbar Radiography Moritz Haager March 4, 2004

Anatomy

Thoracic Spine

Lumbar Spine

Determinants of Stability T & L spines are more stable than C-spine Strong ligaments Stabilization by ribs Bigger intervertebral discs Larger facet joints Less mobility Fractures & dislocations tend to occur where curvature changes T11-12 (thoracolumbar junction) L5-S1 (lumbosacral junction)

Mechanisms of Injury Hyperflexion +/- rotation Shearing Hyperextension Commonest Usually see anterior wedge #’s or Chance # Shearing Ant or post translation Hyperextension Axial loading Compression or burst #’s

3 Column Model Anterior column Middle column Posterior column Ant longitudinal lig Ant annulus fibrosis Ant vertebral body Middle column Post longitudinal lig Post annulus fibrosis Post vertebral body Posterior column Spinous processes Transverse processes Lamina Facet joints Pedicles Post ligamentous complex 2 or more columns disrupted = unstable Most disruption of middle columns are unstable

Stable or Unstable? Radiographic findings suggestive of instability Vertebral body collapse w/ widening of pedicles > 33% canal compromise on CT > 2.5 mm translation b/w vertebral bodies in any plane Bilateral facet dislocation Abnormal widening b/w spinous processes or lamina and > 50% anterior collapse of vertebral body

Stable or Unstable? Checklist for Instability Anterior elements disrupted 2 pts Posterior elements disrupted 2 pts Saggital plane translation > 2.5 mm 2 pts Saggital plane rotation > 5o 2 pts Spinal cord or cauda equina damage 2 pts Disruption of costovertebral articulations 1 pt Dangerous loading anticipated 2 pts 5 or more pts unstable until healed or surgically stabilized

Stable or Unstable? Risk of neurologic injury increases with > 35% canal narrowing at T11-12 > 45% canal narrowing at L1 > 55% canal narrowing at L2 & below

Approach to T & L Spines A – adequacy & alignment B – bones All vertebrae need to be visible Ant & post longitudinal lines Facet joints should lie on smooth curve Normal kyphosis & lordosis All spinous processes should lie in straight line B – bones Trace cortical margins of each vertebrae Difference b/w ant & post body ht < 2 mm Progressive increase in vertebral body ht moving down spine Wink sign & interpedicular distance Don’t forget to look at transverse processes Exceptions: L5-S1 disc space is narrower than above ones TP #’s are in and of themselves stable but markers for serious intraabdominal injury in ~20% of cases

Approach to T & L Spines C – cartilage S –soft tissue Progressive increase in disc space moving down spine (except L5-S1) Facet joint alignment S –soft tissue Look at paraspinal stripe and prevertebral space

Case 1 38 yo female brought to ED after being backed over by car driven by boyfriend Intoxicated; c/o back pain & demonstrating the remarkable versatility of the F-word

Transverse process fractures of L2-4 Significance of transverse process fractures is not the fractures in and of themselves but rather the high incidence of associated serious intraabdominal injury (~20%)

Case 2 46 yo male presents to ED after falling 12 feet off ladder while putting up Christmas lights c/o back pain

Anterolisthesis Of L4 on L5

CT demonstrates chronic anterolisthesis with no intrusion into spinal canal

Case 3 50 yo male again 10-12 foot fall off ladder while putting up Christmas lights (dangerous hobby)

Mild ant wedging of T3 & T4

Mild ant wedging of T3 & T4

Case 4 21 yo belted passenger in rollover single vehicle MVA at highway speed

Anterior wedging of T4 & T5 w/ loss of 30-40% of body ht Widened paraspinal line suggesting hematoma Laterally displaced T5 pedicle Anterior wedging of T4 & T5 w/ loss of 30-40% of body ht CT showed stable fractures

Case 5 29 yo driver offroading in pick-up truck – rolls it at speed Not belted, ejected from vehicle and trapped underneath for 3 hrs

Paramediastinal soft tissue density & widening Suggestive of compression fractures

Case 6 22 yo male single vehicle rollover. Not restrained – ejected through windshield at highway speeds

Posterior displacement Involvement of pedicles & laminar arch Comminution & anterior wedging of L2 w/ 50% loss of body Ht

CT demonstrates severe burst # w/ horizontal plane extending posteriorly through pedicles and transverse processes in keeping w/ a CHANCE fracture

Case 7 58 yo roofer presents to ED unconscious after plunging 12 feet onto concrete through skylight

Schmorl’s node Compression fracture of L3 w/ no obvious post element involvement