thoracic spine trauma

introduction

initial Mx should be as per trauma
- as per trauma protocols, spinal precautions should be utilised until cleared of potentially unstable injuries and patients should be investigated to exclude blunt renal, liver or spleen trauma, as well as fractured ribs and potential for associated pneumothorax or haemothorax, aortic dissection, etc.
  - see also: trauma to the chest
unstable fractures or thoracic disc herniation may cause spinal cord injury and paraplegia
- in addition, between T4 and T9, the anterior part of the spinal cord is further at risk as the blood supply is dependent upon the anterior spinal artery which may be compromised in trauma or herniation of disc
at Western Health, spinal injuries are managed by neurosurgery (either WH or RMH neurosurg reg), NOT by orthopaedics

a rib is attached to each thoracic vertebral body and is named the same number as the body, as is the digital nerve that exits under that rib
T1-4 share some features with the cervical vertebrae
- T1 has a long spinous process and a complete costal facet on it's superior aspect for the 1st rib
T5-8 are then typical thoracic vertebrae
- the coronally orientated facet joints (plane of arc of movement is centered around the vertebral body) means that there is very limited flexion/extension but considerable lateral flexion and rotation is possible
T9-12 share some features with the lumbar vertebrae although there is a distinct transition at T12 which makes T12 the most at risk for injury in trauma due to the transitional stresses
in a sagittal plane, the thoracic spine is said to consist of 3 columns:
- anterior column:
  - anterior spinal ligament
  - the anterior annulus fibrosis and the intervertebral disk
  - the anterior two thirds of the vertebral bodies
- middle column:
  - posterior aspect of the vertebral bodies
  - the posterior annulus fibrosis
  - the posterior longitudinal ligament
- posterior column:
  - all of the spine posterior to the longitudinal ligament

height of the vertebral body is maintained posteriorly but compression of the anterior aspect results in wedge appearance
the most common fracture type, particularly in the elderly or those with osteoporosis
surgical Mx may be indicated if:
- posterior ligamentous injury is likely to be present as well:
  - a compression of more than 40% of the anterior vertebral wall, or,
  - a kyphotic deformity of more than 25° is often associated with
otherwise these are generally stable and rarely cause neurologic problems
- consider a thoracolumbar brace for 6-12 weeks and gradual introduction of physical activity and rehabilitation exercises

loss of height of both posterior and anterior aspects of the vertebral body
often caused by a fall from a height and landing on the feet
it is important to assess:
- the percentage of canal compromise
- the degree of angulation
- neurologic status
unstable injuries generally require surgery:
- significant comminution
- severe loss of vertebral body height
- canal compromise > 40%
- excessive forward bending or angulation at the injury site
  - eg. the kyphotic deformity > 25°
- significant nerve injury due to parts of the vertebral body or disk pinching the spinal cord
other cases may be treated as for compression wedge fractures
- ie. the patient may require a TLSO brace worn for at least 12 weeks

distraction fracture with the vertebral body pulled apart as in a high speed car accident with pelvis immobilised by a lap seat belt (risk is now much lower with seat belts with a shoulder component), it is now perhaps more common with falls than from car accidents
it is caused by violent forward flexion, causing distraction injury to the posterior elements
mainly occur at T12-L2 (and mid-lumbar region in children)
consists of a compression injury to the anterior portion of the vertebral body and a transverse fracture through the posterior elements of the vertebra and the posterior portion of the vertebral body
~50% of patients with Chance fractures have associated intraabdominal injuries - particularly to pancreas, duodenum, and mesentery
on the lateral films, look for a horizontal fracture through the spinous process, laminae, pedicles and vertebral body
same mechanism of injury may not produce a fracture in children but may still be associated with intestinal and urinary bladder injuries
surgery may be indicated if:
- associated injury to the posterior ligaments of the spine
- involves the disks of the spine
other cases may be managed with a thoracolumbar brace for 12 weeks
see also: http://www.learningradiology.com/notes/bonenotes/chancefxpage.htm

similar to a Chance fracture but the fracture line extends anteriorly through the vertebral body to its anterior aspect

fracture line involves the superior articular processes, the arch, and a small posterior fragment of the sup/post. aspect of the vertebral body
spinous process is intact however, the posterior ligaments are disrupted

generally caused by rotational injury such as high speed car accidents
all 3 columns of the spine are disrupted
frequently cause serious spinal cord compression and thus require spinal precautions and assessment and Mx of spinal cord injury, and surgical stabilisation

less commonly symptomatic than lumbar disc prolapse but potentially more serious
most commonly involved T11 and T12
higher levels can be involved if either:
- sudden, forceful twisting of the mid back, or during a fall or car accident
herniation at T4-T9 runs risk of compromise to anterior spinal cord blood supply by pressure on the anterior spinal artery