A 13 year old boy presents to ED after jumping out of a window trying to sneak out his bedroom at night time. He is complaining of pain in his lower back. How do we identify and treat a potential thoracolumbar spine injury?
To see a step-by-step guide on how to interpret thoracic or lumbar spine x-rays then take a look at our post on this here.
Understanding the anatomy
The spine can be split into three regions to help understand the mechanics.
From The Radiology Assistant – https://www.radiologyassistant.nl/en/p4906c8352d8d2/spine-thoracolumbar-injury.html
The upper region is T2-T10 – this region is pretty firm and a consequently less common to have fractures. It is firm and more stable because it articulates with the ribs which articulate with the sternum; the intervertebral discs are thin; and the kyphosis means that your centre of gravity here is anterior to the spine. In a compression injury you get compression anteriorly.
The transition region is T10-L2 – this is the region where most injuries occur. It’s a transition between the kyphosis above and the lordosis below. It’s also a transition between the immobile upper region and the mobile lumbar region.
The lower region is L3 to the sacrum. This region is flexible. It’s the most common location for axial loading injuries. The centre of gravity is posterior to the spine. With the lordosis, when there is a flexion injury, the lumbar spine actually straightens up and this causes burst fractures.
The patterns of injury in the upper and lower region are nicely illustrated in this image from the Radiology Assistant
The spinal cord ends and the cauda equina begins at L1/L2.
How do thoracolumbar fractures happen?
Thoracolumbar fractures are most commonly the result of high-impact injury – specifically 60% are due to motor vehicle accidents or falls from heights landing on the patient’s feet or bottom. As these are most commonly high-impact mechanisms they are often associated with other trauma injuries e.g. pneumothorax, or rib fractures. In patients with spinal injuries due to seatbelts these are often associated with intra-abdominal injuries too.
Thoracolumbar spinal injuries are missed in up to 20% of cases, often due to distracting injuries.
Most thoracolumbar injuries (60%)Â affect the transition region (T11-L2), 25% affect the thoracic spine and 15% affect the lumbar region. (Magerl et al)
Conduct a thorough assessment
Assessment should include a history of the mechanism. Pain can often be axial, or described as a non-radiating stabbing or aching pain. Neurological symptoms can be paraesthesia or anaesthesia below the level of the injury, weakness, or urinary retention.
Risk factors include: fall from a height of greater than 3 metres; axial load to the head or base of the spine – for example, falls landing on feet or buttocks; and high-speed motor vehicle collision. (NICE, 2016))
Inspect the spine by log-rolling the patient – look and feel for any bruising, abrasion, tenderness, or a gap between spinous processes. Do a full neurological exam to check for any impairment.
If you decide on no imaging (because the patient examines normally) then make sure you assess mobility. Specifically check for pain on sitting, standing, and walking.
Which type of imaging should I choose?
X-rays should be the first line investigation in those with a suspected injury T1-L3 but without any neurological signs (NICE, 2016). If the x-ray is abnormal or there are signs of a spinal column injury then perform a CT. Make sure you discuss the XR with a paediatric radiologist to decide on further imaging. Consider specifically whether the images offer adequate views.
There is ongoing debate about XR v CT as a first line investigations –Â intra-observer agreement is higher with a CT so some may argue that CT is more reliable and should be gold standard (although it should be noted that CTs also lead to false negatives). This has to be weighed against the increased radiation risk from a CT v an XR (10 times the amount of radiation). The most important reason for imaging is to rule out clinically significant injuries. This is similar to our decision to perform a head CT in a children with head injuries – we CT based on the likelihood of picking up a clinically significant traumatic brain injury and know that we may miss some insignificant skull fractures.
A CT scan will provide further information about the nature of the bony injury once there has been an abnormal x-ray.
MRI provides information about spinal cord injury, cord oedema, or any haemorrhage. It can also evaluate any injuries to the ligaments. It should be performed if there are neurological signs or suspicion of a spinal cord injury.
Is the fracture stable?
Stability is the basis for surgical intervention and is based on the ability to prevent neurological injury and progressive deformity if the patient continues to mobilise as normal. We most commonly use Denis’ three column model to assess stability.
The spine is split into three columns – anterior, middle, and posterior.
The anterior column is the anterior two thirds of the vertebral body with the anterior longitudinal ligament
The middle column is the posterior third of the vertebral body with the posterior longitudinal ligament.
The posterior column is the pedicles, facets, spinous processes, lamina, and the posterior ligamentous complex, and the intervertebral discs.
From Radiology Assistant – https://www.radiologyassistant.nl/en/p4906c8352d8d2/spine-thoracolumbar-injury.html
If only one column is disrupted then the injury is stable, but if more than one column is disrupted then the injury is not stable. A burst fracture is often unstable because it involves the anterior and middle columns. However, often with a middle column injury but an intact PLC, a two-column injury can be managed conservatively. The PLC is a key component of determining stability.
What is the PLC?
The posterior ligamentous complex is made up of four ligaments all helping to stabilise the spine.
The supraspinous ligaments connect the tips of the spinous processes. The interspinous ligaments are weak and thin, and connect the adjacent spinous processes. These two ligaments limit the flexion of the spine.
The ligamentum flavum is thick and broad, and connects the laminae of the adjacent vertebrae. During flexion, the ligamentum flavum keeps the vertebrae aligned.
The facet capsule is covered with hyaline cartilage on the articulating surfaces. They act against torsional or rotational forces.
The PLC is essential to act to stabilise the spine against the anterior forces that exist due to our centre of gravity.
How do we classify the injury?
There are many different types of classification of injuries, but the Thoraco-Lumbar Injury Classification and Severity Score (TLICS) rests on three key aspects: morphology of injury; PLC involvement; neurological status. These aspects are used to determine the clinical management. This classification is particularly useful because (unlike the Denis model) it takes into account the PLC and the neurological status of the patient.
The morphology has four possibilities and get a score of 1-4: compression; burst; translation/rotation; or distraction. This assessment will be made based on an x-ray or CT.
Compression injuries (1 point) are described by loss of vertebral body height or endplate disruption. Less severe compression injuries may involve just the anterior aspect of the vertebral body.
Burst fractures (2 points) usually involve more force and involve the posterior aspect of the vertebral body (often from axial loading or lateral flexion).
Translation or rotation (3 points) is where one vertebral body is displaced or rotated in relation to another. These are often due to shearing forces or torsion. AP translation will be best seen on the lateral XR view and medial displacement will be best seen on the AP view. Translation/rotation is due to a side-to-side motion (can be left-to-right or front-to-back). It is a serious injury and always involves the posterior ligamentous complex.
Distraction injuries (4 points) are where the vertbrae are pulled apart and carries a high risk of cord injury. Often there is compression at the other side (see Chance fracture below).
The posterior ligamentous complex is either intact (0 points), suspected injury (2 points), or confirmed injury (3 points). This assessment will be made based on an MRI.
And the neurological status is either intact (0 points), nerve root (2 points), complete cord (2 points), incomplete cord (3 points), or cauda equina (3 points). This is assessed by doing as neurological examination.
From https://pubs.rsna.org/doi/pdf/10.1148/rg.337135018
What intervention is required?
The TLICS score acts as an indication for surgical intervention. The guide being that <3 does not need surgery, 4 is at the surgeon’s discretion, and >4 likely requires surgery.
Involvement of the PLC complex will require surgical stabilisation otherwise it will lead to poor healing, kyphosis, and vertebral collapse.
Most thoracolumbar spine fractures can be managed conservatively. Stable burst fractures or simple compression injuries can be managed with a brace which allows early mobilisation and prevents hyperextension. There is some debate about the benefit of wearing a brace v mobilising without and a systematic review showed that there was no benefit in wearing a brace in thoracolumbar traumatic fractures.
Timothy has a T12 compression fracture on XR, which is confirmed on CT. He has no neurological signs. He is discharged with analgesia and will be followed up in clinic in a couple of months time.
References
Spinal injury: assessment and initial management, NICE guideline, 2016
