Fractures and dislocations of the spine can be divided based on the location or the mechanism of trauma. Both parameters are important as location of the spine fracture can risk neurological compromise of varying degree. Fractures from the cranio-cervical junction down to thoracolumbar junction can both damage the spinal cord and/or nerve roots, while fractures on the lumbar spine below L1, can only damage nerve roots.
C1-fracture
The first cervical vertebra or Atlas is a ring. Its major function is to translate the mobility between the skull and the rest of the vertebral column below it. This translation of the mobility is made through the unique form of C1 and C2 along with associated ligaments. Fractures of C1 can be unilateral fracture of the C1-ring or bilateral fractures of the C1-ring that classically are called Jefferson-fractures.
C2-fracture
The C2, also called the Axis, together with C1, translate the mobility form the skull to the rest of the spinal column below it. C2 has a unique form consisting of a ring with an anterior process called the odontoid process or the Dens. C2, beside its classical facets (joints) towards the above-lying C1, and the below-lying C3, has a third pseudo-joint between its odontoid process and C1. C2 and C1 have extensive ligamentous connections between them and towards the skull, being the main parameters of the craniocervical stability. C2 has an elongated section between its superior and inferior facets and hence has an elongated pars interarticularis, which suits well for positioning screws for surgical fixation. Given C2-unique anatomy, fractures of the C2 can include its lamina, its facets, its Pars Interarticularis and the Odontoid Process (Dens). There are 3 types of fractures of the Odontoid Process: Type 1: Fracture above the Transverse Ligament. Type 2: Fracture below the Transverse Ligament but above the body of the C2. Type 3: Fractures at the base of the Odontoid process (Dens).
Hangman fracture
This is a traumatic C2-3 olisthesis. It is due to disruption of the bilateral C2 pars interarticularis, caused by hyperextension and distraction as in high-speed motor vehicle accident. Based on Efendic-classification, there are 3 types:
Type 1: Pars fracture diastase less than 3 mm
Type 2: Pars fracture diastase more than 3 mm
Type 2A: Pars fracture diastase less than 3 mm but with significantangulation
Type 3: Type 1 with BilateralFacet dislocation and/or Traumatic Disk herniation
Type 1 can be treated with brace or Halo. Type 2 and 3 need surgery.
Ligament of the Cranio-cervical
These ligaments are crucial for stability of the cranio-cervical junction. The anatomy and function of each of them are well delineated in the following manuscript.
Sub-axial Fractures (C3-7) All fractures below C2/Axis, are called sub-axial. They usually have a body, pedicles, lateral masses and lamina. The lateral masses are larger than the pedicles in C3-6 and are more suitable for screw placement instead of the small pedicles. C7’s pedicle has a size suitable for screws. Fractures can affect the body, pedicle, lateral mass, lamina and facets. The mechanism of fracture, can be compressive, distractive or translational. We will discuss this more in detail under Thoracolumbar fractures.
Thoracolumbar fractures Fractures occurring in the thoracolumbar spine are among the most common.
Three-Column-Theory
The Anterior Column consists of the Body excludingthe pedicles, the disk and the Anterior Longitudinal Ligament (ALL). The Middle Column consists of the Pedicles, the Posterior Longitudinal Ligament (PLL) and the facets. The Posterior Column consists of the Lamina, the Inter-spinal ligament and the Supra-spinal ligament. Naturally, the more columns involved , the more unstable a fracture is.
Magerl-Classification Another important concept is Magerl’sground-breaking classification of thoracolumbar fractures based on the mechanism of injury. It is important to consider spine fractures together with an associated dislocation.
Type A: Compression Injury
A1: Mild Compression Fracture
A2: Split Fracture
A3: Burst Fracture
Type B: Distraction Injury
B1: Unilateral Facet Fracture/dislocation
B2: CHANCE-fracture: 3 types: Bony, Ligamentous, Mix
B3: Bilateral facet fracture/Dislocation
Type C: Translational Injury
C1: Anteroposterior dislocation
C2: Lateral dislocation
C3: Rotational Dislocation
With the above 3-column-theory and Magerl’s Classification of the mechanism of injury, thoracolumbar fracture/dislocations can be easily classified and be treated thereafter. The above simplifies the communication between the physicians in respect to the type of injury.
Etiology (cause) of the fractures. Traumatic fractures secondary to trauma Pathological fractures, secondary to malignancy. Osteoporotic Fractures secondary to Osteoporosis/Osteopenia. The decision to surgically intervene depends on the stability of the spinal column and involvement of the spinal cord. Most compression fractures do not require intervention and will heal over time as the bone remodels. Bracing (Orthosis) is optional. Burst fractures can be treated conservatively or with surgery depending on degrees of the burst-component, high-loss of the column, kyphotic deformation of the column and presence of posterior element injury. Chance fractures except for non-displaced bone-chance fracture, bilateral facet fractures/dislocations and all translational fracture-dislocation often require surgery to provide greater integrity to the spine and to ensure proper healing. In addition, fractured bone may impinge on the spinal cord and cause neurologic deficits, in which case surgery is emergent. Often, fixation and fusion will be required classically 2 levels above and below the affected segment. If a fracture between a stable segment such as the thoracic and a mobile segment such as cervical or lumbar, the fixation/fusion needs to be 2 levels beyond the transition of the cervico-thoracic and thoracic-lumbar segment. Pedicle screws can add greater support to the fusion. Lateral masses are larger than the pedicles in C1 and C3-6 and are usually used. C2’s pars interarticularis is large and can be used for screw fixation. Corpectomy/Vertebrectomy may be required to resect a severely injured body, especially if the thecal sac is compressed by bone fragment. Bracing may be recommended following surgery.
Sacral Fractures
Fractures of the sacrum are associated with pelvic injuries and usually caused by high-energy, traumatic accidents. Pelvic insufficiency fractures can be seen in older women, especially with osteoporosis. The Denis Classification System is used to assess the stability and extent of neural involvement in sacral fractures.
Case courtesy of Dr Matt Skalski, Radiopaedia.org. From the case rID: 23215
As illustrated above, zone 1 fractures occur lateral to the neural foramina. In zone 2 fractures the neural foramina is involved, but not the spinal canal. Zone 3 fractures are medial to the neural foramina and involve the spinal canal. Zone 3 fractures are sub-divided into 4 different types:
type 1: only kyphotic angulation at the fracture site (no translation)
type 2: kyphotic angulation with anterior translation of the distal sacrum
type 3: kyphotic angulation with complete offset of the fracture fragments
type 4: comminuted S1 segment, usually due to axial compression
Zone 3 fractures have the highest rate of neurologic deficit and may affect bowel and bladder continence or cause sexual dysfunction. These complications may be seen in up to 60% of patients. Zone 2 fractures may be stable or unstable but have increased risk of nonunion and poor functional outcome relative to zone 1 fractures. Zone fractures are associated with nerve injury in only 5% of patients. Typically the L5 nerve root is involved.
Most sacral fractures resolve non-operatively. In those with fracture displacement >1 cm, soft tissue compromise, persistent pain, and neural deficit, surgical intervention may be considered. Closed or open reduction and internal fixation may be undergone with neural decompression as needed.
Coccygeal Fractures
Coccygeal fractures occur following damage to the coccyx, or “tailbone,” of the spine. These may happen as a result of trauma or following childbirth. Risk factors include reduced muscle mass, elderly age, osteoporosis, female gender, and participation in certain activities such as skating. Symptomatic presentation includes localized pain that increases in severity while sitting or rising from a chair, or during bowel movements. Bruising or edema may be observed over the coccyx. Abnormal coccygeal movement may be palpated during a rectal exam by a physician. X-rays may or may not be required for diagnosis.Surgery is rarely required for treatment, only for displaced fractures. Conservative management with use of a donut cushion for sitting is recommended. References Baaj AA, Mummaneni PV, Uribe JS, Vaccaro AR, Greenberg MS. Handbook of Spine Surgery. 2nd Ed. New York: Thieme Medical Publishers, 2016. Kyphoplasty for compression fractures Compression fracture of vertebra is the collapse of vertebral body of spine. These compression fractures of thoracolumbar spine are the most common in elderly and occur in approximately 25% of all postmenopausal women during their lifetime in United States3. Approximately 1.5 million compression fractures of vertebra occur annually in general US population4. The most common cause of vertebral compression fracture is osteoporosis but it can also be caused by trauma, infection, and tumor of spine. Vertebral compression fracture can lead to acute or chronic back pain. Depending on the intensity of your pain, your physician can recommend vertebral kyphoplasty which is a minimally invasive procedure and can be performed under local or general anesthesia. In this procedure, your surgeon will make two small incision in your back through which two specialized tubes are inserted directly into fractured vertebral body. Though each tube, a balloon is inserted on each side and then they are inflated to expand the collapsed vertebral body and to re-establish its original height. This expansion will create an empty space within the vertebral body. Once the desired height is achieved, the balloons are deflated and removed from the body. Subsequently your surgeon will inject highly viscous bone cement which is made of methylmethacrylate. This bony cement will act as an adhesive to stabilize the vertebral body and to prevent the vertebral body from collapse.
References
- Baaj AA, Mummaneni PV, Uribe JS, Vaccaro AR, Greenberg MS. Handbook of Spine Surgery. 2nd Ed. New York: Thieme Medical Publishers, 2016.