Thoracic and Lumbar Trauma

1. Thoracic and Lumbar Trauma

2. Thoracic Compression Fracture • M.C. at T11 and T12 • Hematoma may cause displacement of the paraspinal stripe on AP film • Wedge shape vertebra on lateral film http://orthoinfo.aaos.org/topic.cfm?topic=A00538 http://download.imaging.consult.com/ic/images/S1933033207730938/ gr3-midi.jpg

3. Thoracic Fracture-Dislocation • M.C. T4-T7 • Often associated with neurological damage because canal is small and blood supply is sparse • Rad features include loss of vert. body height, displacement, widened interpediculate distance and widened paraspinal stripe *Best appreciated on CT http://www.ajronline.org/cgi/content-nw/full/187/4/859/FIG12

4. Lumbar compression Fractures • M.C. fxs. of L/S; L1 is m.c. • In elderly, due to osteoporosis (insufficiency fx) • Stability is determined based on Denis’ 3-column model • Anterior- from ALL to mid-vertebral body • Middle- from mid-vert. body to PLL • Posterior- from PLL to supraspinous lig. • Disruption of 2 or 3 columns implies instability • Likelihood of neurological injury is high and interventional surgery is likely necessary http://www.nrmedical.net/nrpd-xrayreporting.asp http://www.radiologyassistant.nl/en/4906c8352d8d2

5. Rad. Signs of Vert. Compression Fxs. • Step defect- buckling of the anterior cortex, near the superior vertebral endplate on lateral view • Wedge deformity- anterior depression of the vertebral body occurs, creating a triangular wedge shape • Up to 30% or greater loss in anterior height may be required before the deformity is readily apparent on convention x-rays • Normal variant anterior wedging of 10-15% or 1-3 mm is common thought the T/S and most marked at T11-L2 http://www.ski-injury.com/specific-injuries/spinal1

6. Rad. Signs of Vert. Compression Fxs. • Zone of Condensation- band of radiopacity below sup. Endplate represents the early site of bone impaction following a forceful flexion injury where the bones are driven together • If present, denotes a fracture of recent origin (<2 months’ duration) • Paraspinal edema- U/L or B/L hemmorrhage may occur • Displaces paraspinal stripe on AP T/S; creates asymmetrical densities or bulges in psoas margins on AP L/S http://download.imaging.consult.com/ic/images/ S1933033207730938/gr3-midi.jpg http://www.dynamicchiropractic.com/mpacms/dc/article.php?id=51049

7. Rad. Signs of Vert. Compression Fxs. • Abdominal ileus- seen radiographically as excessive amount of small or large bowel has in a slightly distended lumen • Warns that the trauma was severe and fracture is likely • Results from disturbance to the visceral autonomic nerves or ganglia from pain, paraspinal soft tissue injury, edema or hematoma http://www.ganfyd.org/images/thumb/6/69/Axr_ileus.jpg/ 180px-Axr_ileus.jpg

8. Old Vs. New Compression Fracture • Previously mentioned signs disappear with healing, which could be up to 3 months in adult • DJD develops due to altered mechanics • MRI reveals bone marrow edema with recent fracture up to 6 weeks post trauma http://www.dynamicchiropractic.com/mpacms/dc/article.php?id=51049

9. Burst Fractures • Compression fracture where posterosuperior fragment is displaced into the spinal canal • Neurological injury in up to 50% of cases (best demonstrated by MRI or CT) • AP film shows vertical fracture line, which differentiates from simple wedge comp. fx. • Widening of the interpediculate distance signifies a fracture within the neural arch • Acquired coronal cleft vertebra – coronally oriented fracture the separates the vertebral body into anterior and posterior halves • Central depression of the superior and inferior endplates occurs with comminution of the vertebral body http://radiopaedia.org/images/11020

10. Burst Fractures http://www.medscape.com/content/2004/00/48/20/482043/482043_fig.html

11. Posterior Apophyseal Ring Fractures • Separation of the posterior vertebral body ring apophysis (posterior limbus bone) is a relatively uncommon abnormality • Most common levels are L4/5 and L5/S1 • 50% are caused by trauma, such as weightlifting, MVAs, gymnastics • Between 15% and 20% are visible on lateral radiographs, but CT is definitive • Surgery may be warranted after failure of conservative care and in the presence of significant neurological compromise http://www.sciencedirect.com/science/article/pii/S089970711200037X

12. Kummel’s Disease • Post- traumatic vertebral collapse, caused by rarefying process in vert. body months after trauma • Results from complicating avascular necrosis resulting in progressive compression deformity • Intravertebral vacuum phenomenon may be evident on radiographs http://radiopaedia.org/cases/kummell-avn?fullscreen=true

13. Fractures of the Neural Arch • Transverse process fractures- 2nd m.c. L/S fx. • Occur from avulsion of the paraspinal muscles, usually secondary to a severe hyperextension and lateral flexion blow to the L/S • M.C. at L2 and L3 • Loss of the psoas shadow may occur secondary to hemorrhage • Large forces involved, so organs may be damaged as well • Pars interarticularis fractures- acute fxs (not stress fxs.) are rare • Violent hyperextension of L/S, usually at L4 or L5 • Usually unilateral, not bilateral like stress fx. • Heal without residual defects or anterior displacement http://openi.nlm.nih.gov/detailedresult.php?img=2776377_JETS-02-217-g001&query=the&fields=all&favor=none&it=none&sub=none&uniq=0&sp=none&req=4&simCollection=2762171_IJO-43-234-g001&npos=36&prt=3 http://www.sciencedirect.com/science/ article/pii/S1529943011014033

14. Chance or Lap Seat Belt Fracture • Aka fulcrum fracture; seat belt acts as fulcrum over abdomen • Horizontal splitting of the spine and neural arch • Internal visceral damage may occur – rupture of the spleen or pancreas and tears of the small bowel and mesentery • M/C location is upper L/S (L1-L3) • AP radiograph shows transverse fracture through the posterior elements and angulation of the superior portion of the fractured vertebra • The resulting widened radios gap between the two fractured segments has been turned empty vertebra • Lateral radiographs shows radiolucent split through spinous process, lamina, pedicle and upper corner of the posterior aspect of the vertebral body http://www.radiologyassistant.nl/en/4906c8352d8d2

15. Fracture-Dislocation • Usually at thoracolumbar junction after a violent flexion injury • Avulsion fractures (teardrop) are commonly found associated with dislocation of the L/S • Most dislocations are anterior in position, without lateral displacement • Complete luxation with lateral shift of spine may create cord or cauda equina paralysis • Axial CT shows absence of apposed articular facets (naked facet sign) http://www.ajronline.org/content/187/4/859/F4.expansion.html

16. References Yochum, T.R. (2005) Yochum and Rowe’s Essentials of Skeletal Radiology, Third Edition. Lippincott, Williams and Wilkins: Baltimore.