Upper Cervical Spine Injury
The upper cervical spine injury that occurs in two unique vertebrae, the atlas (C1) and the axis C2) and adjoining structures. The skull base with its bony and ligamentous elements surrounding the foramen magnum plays an integral part in the maintenance of the normal functional alignment of these two cervical vertebrae.
Technically, however, skull base is not a part of the upper cervical spine.
Upper cervical spine injury also includes all osseous and ligamentous structures between the skull base and the cranial side of the C-3 vertebra.
The integrity of the craniocervical junction is of crucial for survival and function. It is here that transition from brainstem to spinal cord occurs. These vertebrae are shaped differently from rest of the cervical spine to protect these vital structures and allow for mobility of the head.
An injury to osseoligamentous components in this region may, therefore, compromise the structural integrity of the entire craniocervical junction and therefore needs to be addressed separately from rest of cervical spine.
Because of complex anatomy and a major role played by ligaments instability, this region is quite vulnerable to injury in high energy trauma. This unique composition also makes the assessment difficult and aid of imaging studies becomes very important.
The assessment should be performed according to standard guidelines and should include cranial nerve examination. Prior to the advent of trauma management systems, these injuries were almost always fatal but the survival has been improving with better management.
In conscious, oriented patients the symptoms of neck pain, headache, and tenderness in the area might suggest the injury to this area.
Neurologic deficits range from complete high quadriplegia to incomplete injuries, such as cruciate paralysis or disorders affecting brainstem function.
Unconscious patients pose an increased diagnostic challenge and need to be scrutinized for the possible spinal column and cord injury. The imaging studies play a greater role in these cases.
Biomechanics of Upper Cervical Spine Injury
The three bony components of the upper cervical spine are
- Skull base
these three components form a functional unit. There are five joints in the upper cervical spine which are stabilized by ligamentous check rein and muscular control.
Together these contribute to the movements in the neck substantially. This enables us for a rapid response and large-scale head excursion.
The normal axial plane C1–2 rotational excursion amounts to 80 to 88 degrees from left to right.
Total left to right lateral bending at the C1–2 segment amounts to 20 degrees.
The alar ligaments play a key role in protecting normal craniocervical motion. At mid position of the head, these ligaments are slack.
By turning the head in one direction, the alar ligament contralateral to the direction of turning tightens, while the ipsilateral ligament slackens. Together with the tectorial membrane, the alar ligaments limit flexion but they play no role in limiting extension.
Other ligamentous stabilizers of the craniocervical junction are the cranial portions of the anterior longitudinal ligament and posterior longitudinal ligament of the spine and joint capsules of the respective articulations.
Anteriorly, the well-developed atlantooccipital membrane limits extension, with the thinner anterior atlantoaxial membrane contributing to a less significant degree.
A number of smaller ligaments, such as the apical and cruciate ligaments, the obliquely aligned accessory atlantoaxial ligaments, the anterior atlantodental ligament, and the facet joint capsules also provide support.
The specific arrangement of ligaments at the craniocervical junction utilizes the atlas as a washer or base for a coupled, multiplanar motion.
The combination of a high degree of motility and relatively delicate ligamentous and bony structures makes the upper cervical spine susceptible to injury from indirect high-energy trauma.
Fracture-dislocations of the craniocervical junction is the leading cause of death of motor vehicle accidents.
The atlas is the most fragile vertebral segment in humans. It will fracture with as little as 1 to 2 mm of deformation and is very susceptible to bursting-type fractures with relatively low axial loads.
The two most vulnerable bony structures of the axis are the pars interarticularis and the odontoid waist. Forced hyperextension can lead to failure of either structure.
Flexion is believed to be causative in 80% of odontoid fractures by forcing the transverse ligament against the odontoid.
Atlantoaxial rotation of more than 50 degrees in either direction as measured by CT scan is suspicious for alar ligament insufficiency.
If it is more than 56 degrees, it is diagnostic of disruption.
An intact transverse ligament limits anterior subluxation of the atlas relative to the axis to 3 mm in adults and 5 mm in children.
Similarly, more than 5 degrees of atlantoaxial flexion indicates transverse ligament insufficiency.
If atlantoaxial translation exceeds 9 mm in adults, comprehensive failure of all key craniocervical ligaments has to be assumed.
Imaging in Upper Cervical Spine Injury
Lateral cervical spine x-ray is the most important trauma screening study. However, clearance of the cervical spine is not possible on basis of the single lateral plane study. Moreover, the typical lateral cervical spine x-ray is centered in the mid-neck region and the interpretation of the occipitocervical junction can be impaired.
To be able to rule out injury following bony structures need to be seen on x-ray
- Opisthion -On the occipital bone, the mid-point on the posterior margin of the foramen magnum
- Occipital condyles
- Mastoid processes
- Tip of the dens
- Outline of atlas and axis
These structures should be visualized in a trauma situation and looked for fracture, rotation, and displacement.
The occipitocervical and atlantoaxial joints should be assessed for congruence.
In adults, widening of the prevertebral soft tissue mass in the upper neck is an important warning sign of major underlying trauma.
Various Reference lines can help in identifying the alteration in normal upper cervical spine outline.
Anteroposterior visualization of the upper cervical spine requires either an open-mouth odontoid view. Normally symmetrical articulating occipital condyles, C-1 lateral masses, and C-2 superior articular processes can be visualized. The odontoid is well centered between the lateral masses of C-1.
In this view, there should be no overhang, translation, or distraction between the lateral masses of C-1 and C-2. The articular surfaces of the occipital condyles to the C-1 superior facets and those of the atlantoaxial articular surfaces should be equidistant from one another.
Other x-rays that can be done to evaluate the upper cervical spine are oblique views, one lower cervical spine anteroposterior x-ray, which usually exposes C4 to T4, and a swimmer’s lateral view.
Dynamic radiographs of the cervical spine are used to find any ligamentous injury to the region.
Any odontoid asymmetry relative to the lateral masses of the atlas or any diastasis of the upper cervical spine articulations to one another is cause for concern about a ligamentous injury to this region.
Dynamic studies should not be done in patients with suspected occipitocervical dissociation because of their potential to inflict neurologic compromise. Also, flexion-extension radiographs are contraindicated for patients with known acute cervical spine fractures and dislocations.
Computed tomography is a crucial investigation tool in the assessment of patients with known or suspected cervical spine fractures.
CT scans allow for high-resolution imaging and make diagnosis easier. By digital reconstruction of the fracture fragments, articular incongruities, complex fracture patterns and visualizing axial plane fractures can be understood.
A head CT scan incorporating the craniovertebral junction can be helpful in detecting subarachnoid craniovertebral junction hematoma, which is frequently associated with atlanto-occipital dissociation, and occipital condyle fractures, which are commonly missed on conventional radiography.
Magnetic Resonance Imaging
Magnetic resonance imaging of the craniovertebral junction is indicated for patients with spinal cord injury, and it can be helpful in assessing upper cervical spine ligament trauma. Subarachnoid and prevertebral hemorrhage can be readily demonstrated on MRI scans.
Radioisotope-based imaging tests, like technetium-99 bone scan, are rarely required in trauma but can be useful in assessing occult fractures, osteoarthritis affecting the upper cervical spine and in pediatric patients for detection of a nondisplaced growth plate injury.
Occipital Condyle Fractures and Occipitocervical Dissociation
Occipital condyle fractures have previously been viewed as relatively uncommon injuries; but with the increased utilization of CT scanning with reconstructions in the evaluation of suspected spine trauma patients, an increased incidence has been noted. It has been reported to occur in 3-15% of trauma patients. Presence of these fractures indicates high injury trauma.
Occipital condyle fractures may be stable or represent the bony component of occipitocervical dissociation.
Montesano classified these fractures into three categories.
Type I Fractures
These are usually stable fractures and thought to be the result of an impaction injury.
They occur as comminution of the tip of the occipital condyle.
Type II Fractures
These consist of an oblique fracture extending from the condylar surface into
the skull base. Fractures of this nature are likely caused by a shear mechanism and are likely unstable.
Type III Fractures
These are least common of the three.
They occur as a transverse fracture line through an occipital condyle. They are thought to occur as a result of an avulsion.
They are unstable and may represent the bony component of a craniocervical dissociation.
If a unilateral bony injury to an occipitocervical joint is identified, the contralateral side should be looked for any signs of a bony or ligamentous injury.
Due to the association of occipitocervical dissociation, any occipital condyle fracture should be evaluated for it.
Type I and II fractures are usually treated conservatively with immobilization in a rigid cervical collar for 6-8 weeks.
Type III fractures should be treated with halo-vest immobilization if there is a suspicion of ligamentous instability. If there is evidence of craniovertebral subluxation, some authors advocate immediate occiput-to-C2 fusion.
Occipitocervical dissociation is an uncommon injury which can be difficult to identify and has a high mortality. The most common mechanism of injury is that of a pedestrian struck by a car, with a high incidence in pediatric patients.
Obvious signs of instability are translation or distraction of more than 2 mm in any plane, neurologic injury, or concomitant cerebrovascular trauma.
The classification of these injuries is based upon the displacement of the occiput.
- Type I injuries are anterior subluxations and are the most common.
- Type II injuries have vertical distraction greater than 2 mm of the atlanto-occipital joint.
- Type III injuries are posterior dislocations and are rarely reported.
Once an injury is identified, prompt management is of the utmost importance.
Traction is contraindicated.
Treatment consists of immediate halo vest application with reduction of the subluxation and confirmation by CT scanning.
An occiput-to-C2 fusion is required in most cases to provide long-term stability.
Fracture of C1 Vertebra or Atlas
Atlas fractures can be stable or unstable injuries. This fracture has a very high association with injuries to other areas of the spine.
A fracture of the atlas vertebra should cause enough alert to search for injuries in other regions of the spine.
Almost 43% of all C-1 fractures are found to be associated with a C-2 fracture.
Atlas fractures have been divided into following 5 types.
- Transverse process fracture
- Posterior arch fracture
- Anterior arch fracture
- Comminuted or lateral mass fracture
- Burst fracture
Transverse Process Fracture
Extraarticular fractures of the transverse process. While these fractures are usually mechanically stable, the involvement of the vertebral foramen may imply vertebral artery injury.
Posterior Arch Fracture
Posterior arch fractures are caused by a hyperextension mechanism. They are stable fractures.
Anterior Arch Fracture
Isolated anterior arch fractures are subdivided into minimally displaced, comminuted, and unstable. They are caused by a hyperextension mechanism in which the odontoid is thrust against the anterior arch of the atlas.
A blowout fracture of the anterior arch leads to displacement of the odontoid anterior to the lateral masses and is inherently unstable.
Lateral Mass Fracture
Lateral mass fractures are either unilateral intraarticular split type or occur as comminuted fractures. These fractures are caused by lateral flexion or rotational forces. These are unstable fractures.
Bursting-type fractures result from an axial load and split the ring of the atlas into several fragments.
Complete transverse ligament insufficiency is said to occur if the combined overhang of the C-1 lateral masses relative to the lateral mass walls of C-2 is 7 mm or more. Transverse ligament insufficiency signifies instability.
In normal conditions, the articulation of the odontoid process of C2 (axis) with the anterior arch of C1 (atlas) allows for 50% of the cervical lateral rotation.
The ligaments responsible for stability are transverse and alar ligaments. They maintain joint integrity and limit posterior motion of the odontoid process relative to the C1 anterior arch.
An acute injury to this area can cause cord compression and could be fatal.
Acute trauma, usually cervical hyperflexion, hyperextension, or a direct axial load on the head or cervical spine causes atlanto axial injuries. Certain conditions congenital odontoid anomalies, such as odontoid aplasia, odontoid hypoplasia, and a separate odontoid process or os odontoideum and inflammatory processes predispose an individual to these injuries.
Most of these injuries are the result of significant trauma to the head, although they may occur in older patients with a simple fall and striking of the occiput.
The individuals suffering from these injuries present with general symptoms of neck pain, limited range of motion, and torticollis. However, worsening of symptoms like a headache, fatigue, transient upper-extremity paresthesias could be an indicator of this injury.
Quadriplegia due to cord compression may also be a presentation.
The standard protocol of spine injury examination must be followed. More Information on this available here
- Spine Injury initial evaluation
- Spine injury- Detailed Evaluation
An assessment of the airway, breathing, and circulation (ABCs), with immediate stabilization of the cervical spine in a neutral position, must be done. While placing airway, a compromise to the injured spine should be avoided.
High-dose intravenous steroids should be considered in patients with suspected cervical cord injuries to reduce spinal cord swelling.
The findings may be completely normal in asymptomatic patients with a radiographically documented injury.
An MRI may be used to investigate the integrity of the ligamentous complex.
Types of Atlantoaxial Injuries
There are three patterns of atlantoaxial instability. These can present as isolated or combined injury
These injuries cause rotational displacement in an axial plane. Fine-cut CT scans are of utmost importance in diagnosis and measurement of this condition.
These injuries are translationally unstable in a sagittal plane due to the insufficiency of the transverse atlantal ligament. These are inherently unstable injuries.
Injuries are characterized by a multiplanar vertical atlantoaxial dissociation. Atlantoaxial distractive injuries are also referred to as atlantoaxial dissociation and constitute a variant of atlanto-occipital dissociation. This injury is a result of vertical separation as in judicial hanging. Often there is a traumatic separation of both alar ligaments, rendering this injury highly unstable,
TreatmentTreatment decisions should be always made on the basis of a comprehensive evaluation of the patient in general and the injury specifically.
Presence of a spinal cord injury usually requires definitive surgical decompression and instrumented fusion of the injury to maximize chances for neurologic recovery.
Ligament injuries heal poorly when treated nonoperatively.
Nonoperative treatments include bracing, halo vest and cervical traction.
Operative treatment consists of C1 -C2 fusion.
Rupture of Transverse Ligament
This is a pure ligamentous injury of the upper cervical spine and behaves differently from other injuries of C1-C2 region.
Most common cause of this injury blows on the back of the head following a fall.
How Does Transverse ligament Rupture?
The ligament may either be avulsed with a bony fragment from the lateral mass on either side or it may rupture in its substance.
The instability can be reduced on the extension.
Presence of retropharyngeal hematoma suggests an acute injury.
A small fleck of the bone may suggest avulsion of the ligament.
Rupture of the transverse ligament is a ligamentous injury and nonoperative treatment is not effective in this type of injury.
Therefore surgery is almost always needed.
Initial treatment of this injury is by stabilization of the spine using traction.
Definitive treatment involves fusion of C1-C2 vertebrae.
Traumatic Spondylolisthesis of the Axis
Disruption of the neural arch of the axis predominately affects the narrow zone of the pars interarticularis and may be associated with more complex soft tissue injuries.
Injuries to this structure are popularly known as hangman’s fracture.
The term hangman’s fracture originally referred to neck injuries incurred during the hanging of criminals. The most common cause of hangman’s fracture now is a motor vehicle accident with hyperextension of the head on the neck. The occiput is forced down against the posterior arch of the atlas, which is forced against the pedicles of C2.
Hangman’s fractures are the second most common type of axis injuries after odontoid fractures.
A classification of these injuries has been given by Effendi et al. was later modified.
Type I Fractures
Type I fractures are minimally displaced and are believed to be caused by hyperextension and axial loading with failure of the neural arch in tension. Because ligamentous injury is minimal, these fractures are stable.
Atypical fractures that are obliquely displaced are unstable fractures.
Type II Fractures
Type II fractures have more than 3 mm of anterior translation and significant angulation. These injuries result from hyperextension and axial loading that cause the neural arch to fail with a predominantly vertical fracture line, followed by significant flexion resulting in stretching of the posterior anulus of the disc and significant anterior translation and angulation.
The C2-3 disc may be disrupted by the sudden flexion component involved in this injury.
A subtype Type IIa is unstable due to their associated C2–3 disc and interspinous ligament disruption.
Type III Fractures
Type III injuries are relatively rare and constitute a complete unilateral or bilateral C2–3 facet dislocation. A C2–3 dislocation is highly unstable and cannot be expected to be reducible by nonsurgical means
The instability of a traumatic spondylolisthesis of the axis largely hinges on the integrity of the C2–3 discoligamentous elements. These fractures frequently are associated with neurological deficits
The assessment of instability is determined by the amount of sagittal C2–3 translation, and angulation between the end plates and is then assigned to one of five categories
- Grade I – Translation < 3.5 mm, angulation < 11 degrees.
- Grade II- Translation< 3.5-mm , > 11 degrees of kyphosis.
- Grade III – Translation >3.5-mm, <than 11 degrees of kyphosis.
- Grade IV – >3.5-mm translation, >11 degrees of angulation.
- Grade V- Complete disc disruptions.
Type I fractures usually heal with 12 weeks of immobilization in a rigid cervical orthosis.
For type II treatment consists of the application of skull traction through tongs or a halo ring with a slight extension of the neck over a rolled-up towel for 3 to 6 weeks to maintain anatomical reduction. The patient can be mobilized in a halo vest for up to 3-month period.
These fractures usually unite with an initial gap in the neural arch and develop a spontaneous anterior fusion at C2-3
Type IIA fractures are a variant of type II fractures that show severe angulation between C2 and C3 with minimal translation.
They usually have a more horizontal than vertical fracture line through the C2 arch. The recommended treatment is the application of a halo vest with slight compression applied under image intensification to achieve and maintain anatomical reduction.
When reduction has been obtained, halo vest immobilization is continued for 12 weeks until union occurs.
Type III injuries usually have severe angulation and translation of the neural arch fracture and an associated unilateral or bilateral facet dislocation at C2-3. Type III injuries are the only type of hangman’s fracture that commonly requires surgical stabilization.
Open reduction and internal fixation usually are required because of inability to obtain or maintain reduction of the C2-3 facet dislocation.
After posterior cervical fusion at the C2-3 level, halo vest immobilization for 3 months is necessary for the bipedicular fracture and for consolidation of the fusion mass.
Rotary Subluxation of C1 Vertebra On C2 Vertebra
This is an uncommon injury in adults. Rotary C1-C2 subluxation is more common in children and that behaves differently from the injury in adults.
In adults, the injury is caused by motor vehicle accidents and often may be missed in the initial evaluation of the patient.
Following an injury, the patient complains of torticollis and restricted neck motion.
An open mouth view may reveal wink sign. The wink sign is caused due to overriding of the C1-2 joint on one side and normal configuration on the other side.
However, since the atlantoaxial joint permits flexion, extension, rotation, and lateral bending, radiographic asymmetry is produced when the head is tilted laterally or rotated or if a slightly oblique odontoid view is obtained.
CT scan is helpful in defining the injury clearly.
Acute rotary subluxation can be reduced by closed methods. After applying a Halo ring, a gentle traction is used to derotate the skull and C1 vertebra. Spinal cord monitoring is done throughout the procedure.
If a stable reduction is obtained, it is confirmed radiologically and Halo vest is applied.
Done in cases of late detections or failed closed reduction. Using a posterior incision on the neck, the subluxation is reduced manually.
This is followed by C1-C2 fusion.
Immobilization in halo vest is recommended for 8-12 weeks in either type of treatment.
Fractures of the Axis Vertebra
The axis vertebra has unique anatomy and despite fractures to the odontoid or pars interarticularis, is subject to a variety of injuries similar to those found in the lower cervical spine. Several basic fracture types are recognized and can be divided into distinct categories
Fractures are characterized by a fracture line through the C-2 vertebral body that runs horizontally.
It is a burst fracture of C-2 vertebral body.
These fractures are sagittal cleavage fractures are usually highly unstable.
Stable fractures can be treated by conservative means but unstable fractures would require operative treatment.
Approaches To Upper Cervical Spine Surgery
The cervical spine can be approached from the front or from back respectively called anterior and posterior approaches.
The posterior approach is more common than anterior.
This approach is most commonly used in procedures such as C-1 laminectomy, posterior fossa decompression, and C-2 neurolysis to procedures aimed at achieving a fusion between the C1–2 segments with or without the inclusion of the occiput.
Advantages of a posterior approach include a relatively simple anatomic exposure and the possibility to extend the
procedure cranially and caudally as needed. In general, posterior spinal instrumentation constructs are also stiffer than anterior stabilization methods.
There are three main indications for anterior upper cervical spine exposures in trauma
- Screw fixation of type II odontoid fracture
- Anterior cervical plating and fusion of the C2–3 interspace for a displaced type IIa hangman’s fracture
- Anterior arthrodesis of the C1–2 facet joints as a salvage
As in any anterior cervical procedure, correct placement of the incision is important in minimizing technical difficulties.
Some of the pathologies of the upper cervical spine are approached through the mouth and the approach is called transoral approach.
Lower Cervical Spine Injury
Two key components responsible in cervical spine injury are force/load transmission and kinematics (motion). Mostly, cervical spine injury occurs due to both of components being present in different proportions.
One can consider an axial compressive load applied to a single cervical vertebra as a fundamentally pure example of load transmission. Force can be applied in different directions like shear, torsion, tension.
Kinematics refers to cervical vertebral motion. The lower cervical spine that permits motion through intervertebral discs and facet joints and is limited by the anterior longitudinal ligament and posterior ligamentous complex. It can be in a flexion-extension plane, axial rotation and lateral flexion.
Flexion-extension motion is greatest at the C4-C5 and C5-6 segments, averaging about 20 degrees. Axial rotation ranges from 2 to 7 degrees at each of the subaxial motion segments. Lateral flexion is 10 to 11 degrees per level in C2-5 and decreases caudally.
Cervical spine injury alters both load transmission and the kinematics of the cervical spine. The cervical spinal column is extremely vulnerable to injury.
Cervical spine injury can lead to disruption of bone, ligament, or both. Ligaments can fail only in tension whereas the bone can fail under compression, tension, or shear loads.
Cervical spine injury that results in flexion incurs compressive loads upon the vertebral body/disc and tensile loads upon the posterior ligamentous complex [Supraspinous, interspinous ligaments and facet capsules] whereas extension of the cervical spine leads to tensioning of the anterior longitudinal ligament and compression across the facet joints and tensile failure of the anterior longitudinal ligament.
Cervical teardrop fragments are created by the shear failure of the anteroinferior vertebral body.
C3-C7 would constitute lower cervical spine. Lower cervical spine fractures and dislocations are common injuries following major trauma.
Fractures of C6 and C7 account for nearly 40 percent of cervical spine injuries after blunt trauma.
Spinal cord damage is more frequently associated with lower cervical spine injuries than upper.
Cervical spine injury most commonly occurs in adolescents and young adults (15 – 24 years and middle-aged (>55 years)
Classification of Cervical Spine Injury
Injury occurs when forces applied to the head and neck result in loads that exceed the ability of the supporting structures to dissipate energy. The injury can occur by various mechanisms. Due to its anatomy, the spinal cord is very vulnerable to injury in the cervical spine injuries.
Classification of cervical spine injury by Allen is the most accepted classification of cervical spine injury. Six common patterns of injury have been identified and each is further classified into stages based on the degree of injury to osseous and ligamentous structures.
Compressive Flexion Stage 1
There is blunting of the anterosuperior vertebral margin to a rounded contour, with no evidence of failure of the posterior ligamentous complex.
Compressive Flexion Stage 2
In addition to the changes seen in stage 1, obliquity of the anterior vertebral body with loss of some anterior height of the centrum [Central portion of vertebra]. The anteroinferior vertebral body has a “beak” appearance, concavity of the inferior endplate may be increased, and the vertebral body may have a vertical fracture.
Compressive Flexion Stage 3
In addition to the characteristics of a stage 2 injury, fracture line passing obliquely from the anterior surface of the vertebra through the centrum [Central portion of vertebra] and extending through the inferior subchondral plate, and a fracture of the beak.
Compressive Flexion Stage 4
Deformation of the centrum and fracture of the beak with mild (<3 mm) displacement of the inferoposterior vertebral margin into the spinal canal.
Compressive Flexion Stage 1
Bony injuries as in stage 3, but with more than 3 mm of displacement of the posterior portion of the vertebral body posteriorly into the spinal canal. The vertebral arch remains intact, the articular facets are separated, and the interspinous process space is increased at the level of injury, suggesting a posterior ligamentous disruption in a tension mode.
Vertical Compression Stage 1
Vertical Compression Stage 2
Fracture of both vertebral endplates with cupping deformities. Fracture lines through the centrum may be present, but displacement is minimal.
Vertical Compression Stage 3
Progression of the vertebral body damage described in stage 2. The centrum is fragmented, and the displacement is peripheral in multiple directions. Most commonly, the centrum fails, with significant impaction and fragmentation.
The posterior aspect of the vertebral body is fractured and may be displaced into the spinal canal.
The vertebral arch may be intact with no evidence of ligamentous failure, or it may be comminuted with a significant failure of the posterior ligamentous complex; the ligamentous disruption is between the fractured vertebra and the one below it.
Distractive Flexion Stage 1
Failure of the posterior ligamentous complex, as evidenced by facet subluxation in flexion, with an abnormal divergence of the spinous process.
Distractive Flexion Stage 2
Unilateral facet dislocation. Subluxation of the facet on the side opposite the dislocation suggests severe ligamentous injury.
In addition, a small fleck of bone may be displaced from the posterior surface of the articular process, which is displaced anteriorly.
Widening of the uncovertebral joint on the side of the dislocation and displacement of the tip of the spinous process toward the side of the dislocation may be seen.
Distractive Flexion Stage 3
Bilateral facet dislocations, with approximately 50% anterior subluxation of the vertebral body.
Blunting of the anterosuperior margin of the inferior vertebra to a rounded corner may or may not be present.
Distractive Flexion Stage 4
Full vertebral body width displacement anteriorly or a grossly unstable motion segment, giving the appearance of a “floating” vertebra.
Compressive Extension Stage 1
Unilateral vertebral arch fracture with or without anterior rotatory vertebral displacement. Posterior element failure may consist of a linear fracture through the articular process, impaction of the articular process, and ipsilateral pedicle and lamina fractures.
Compressive Extension Stage 2
Bilaminar fractures without evidence of other tissue failures.
Typically, the laminar fractures occur at multiple contiguous levels.
Compressive Extension Stage 3
Bilateral vertebral arch fractures with a fracture of the articular processes, pedicles, lamina, or some bilateral combination, without vertebral body displacement.
Compressive Extension Stage 4
Bilateral vertebral arch fractures with partial vertebral body width displacement anteriorly.
Compressive Extension Stage 5
Bilateral vertebral arch fracture with full vertebral body width displacement anteriorly. The posterior portion of the vertebral arch of the fractured vertebra does not displace, and the anterior portion of the arch remains with the centrum.
Ligament failure occurs at two levels: posteriorly between the fractured vertebra and the one above it and anteriorly between the fractured vertebra and the one below it.
The anterosuperior portion of the vertebra below is sheared off by the anteriorly displaced centrum.
Distractive Extension Stage 1
Either failure of the anterior ligamentous complex or a transverse fracture of the centrum. The injury usually is ligamentous, and there may be a fracture of the adjacent anterior vertebral margin.
The radiographic clue to this injury is abnormal widening of the disc space.
Distractive Extension Stage 2
Evidence of failure of the posterior ligamentous complex, with the displacement of the upper vertebral body posteriorly into the spinal canal, in addition to the changes seen in stage 1 injuries.
Because displacement of this type tends to reduce spontaneously when the head is placed in a neutral position, radiographic evidence of the displacement may be minimal, rarely greater than 3 mm on initial films with the patient supine.
symmetrical compression fracture of the centrum and ipsilateral vertebral arch fracture, without displacement of the arch on the anteroposterior view. Compression of the articular process or comminution of the corner of the vertebral arch may be present.
Descriptive Classification of Lower Cervical Injury
In addition to Allen’s classification of lower cervical spine injuries based on the pattern of the injury, the lower cervical spine injuries can also be descriptive. This usually refers to the part of the cervical spine injured.
This descriptive classification divides the injuries into s vertebral body fractures, facet fractures, pedicle and lamina fractures, or anterior tension band disruption.
This classification is good for day to day communication and description of the injury.
Vertebral Body Fractures
This includes injuries caused to the body of the vertebrae. Vertebral body fractures are readily detected by plain films and CT.
Wedge or Compression Fractures
There is primarily anterior height loss and no posterior vertebral involvement.
A fracture that extends obliquely from the anterosuperior vertebral body to the inferior endplate with the varying involvement of the end plate.
These fractures show extensive vertebral body comminution and varying degrees of height loss. There is also posterior vertebral body involvement and fragment retropulsion.
With any vertebral body fractures, the posterior ligamentous complex can be disrupted.
Injuries to facets are very common.
Facet fractures can be associated with dislocations or other posterior arch fractures.
Facet fractures can be associated with ligamentous injury, leading to subluxation and instability.
Facet subluxations are the result of the facet capsule and posterior ligament disruption.
Facet dislocations mean that facet surfaces are not even partially in appositions as they are in subluxation. Dislocations can be unilateral or bilateral.
Pedicle and Lamina Injuries
These may coexist with facet fractures. Facet and pedicle fractures are known as lateral mass fractures.
Anterior Tension Band Disruption
The anterior longitudinal ligament and the intervertebral disc can fail in tension. Widening of the intervertebral disc space is highly suggestive of this injury and significant spinal instability. Small avulsion injuries of the vertebral body can also occur.
The cervical spine injuries should be considered to be having cord injury until ruled out. Moreover, the cervical spine injury should be suspected in every major trauma.
Manual immobilization of the head and neck should be maintained until a hard cervical collar can be applied.
Airway security and hemodynamic resuscitation are crucial and should take precedence. Tracheal intubation and central line placement are often performed in the emergency and due to a danger of worsening of injury by manipulation, manual cervical stabilization should be maintained throughout the intubation process.
If intubation is not possible, a mask ventilation can be continued until fiberoptic or nasotracheal intubation can be safely performed in a hospital.
Cricothyroidotomy might be the safest alternative for airway control when the spine is highly unstable.
Emergency Management of Cervical Spine Injury
C3-C7 would constitute lower cervical spine. Lower cervical spine fractures and dislocations are common injuries following major trauma.
Fractures of C6 and C7 account for nearly 40 percent of cervical spine injuries after blunt trauma.
Spinal cord damage is more frequently associated with lower cervical spine injuries than upper.
Injuries most common in adolescents and young adults (15 – 24 years and middle-aged (>55 years)
Initial assessment of the ABCs (airway, breathing, and circulation) should be performed and life-saving procedures initiated.
Before removing the collar, the cervical spine should be manually immobilized. Log-roll technique and spinal precautions should be observed at all times.
Maintaining a patent airway and hemodynamic stability are crucial and help in minimizing further ischemia to a compromised spinal cord.
Aggressive manipulation of the neck in order to perform intubation should be avoided.
The neurogenic shock when present should be recognized and managed.
Non-Operative Management of Lower Cervical Spine Injury
A number of lower cervical spine fractures can be managed with nonoperative means. Nonoperative means of treatment include orthoses, skull traction, and halo vest immobilization.
The basic aim of nonoperative means is to align and immobilize the cervical spine and prevent it from further stress till the fracture union occurs.
Orthoses can be cervical or cervicothoracic.
Orthoses decrease motion rather than effect true immobilization.
These orthoses work through padded contact areas strategically located over subcutaneous bony prominences like occiput, spinous processes, scapular spines, acromion processes, clavicles, sternum, and mandible.
Soft cervical orthoses cause little decrease in spinal motion and are most commonly used after cervical strains or sprains.
Rigid cervical orthoses can provide varying degrees of immobilization depending on the construct material and the overall design. They are commonly used for emergent in-field cervical spine immobilization.
Skin breakdown at bony prominences can occur as a complication of cervical collars.
In these orthotic device extends to the upper thorax. These provide more effective immobilization than simple cervical collars in all planes. Sternooccipito-mandibular immobilizer –(SOMI) and Minerva brace are examples of cervicothoracic orthoses.
However, they are more difficult to apply and remove and produce high resting pressures on the chin and occiput.
Both cervical and cervicothoracic devices cause increased motion at cervicothoracic junction.
Traction can be used for temporary immobilization of unstable cervical spine injuries, or to realign or reduce and maintain cervical spine fractures or dislocations. The devices used are Crutchfield’s tongs, Gardner-Wells tongs, and the halo-ring.
Halo immobilization has become a less popular form of treatment for lower cervical spine injuries as the better internal fixation techniques have been developed. Despite this, halo vest immobilization remains a viable, minimally invasive method of stabilization of unstable cervical spine injuries for patients who might otherwise have contraindications to open surgical methods.
Surgical Treatment of Cervical Spine Injury
With the increased choice of implants and gadgets and development of better surgical approaches & techniques, surgery is playing a greater role in the management of cervical injuries as compared to earlier times.
There is still controversy about the optimal time to perform surgery, particularly in patients with neurologic deficits. Advocates of early surgery point at the two benefits of earlier surgery
- Neurological recovery
- Improved ability to mobilize the patient without concern of spinal displacement.
Studies have pointed out that surgery performed within first 72 hours to 5 days have a better outcome but surgery performed within first 24 hours may not.
But specific and substantial evidence that early surgery produces better neurological recovery is yet to come.
The other school of thought believes that surgery should be delayed to allow for optimal medical stabilization of the patient and resolution of initial spinal cord swelling. This school hypothesizes that early surgery may be potentially detrimental due to spinal cord edema and it is worthwhile to wait for the stabilization of the patient.
Surgery can be done with the anterior or posterior approach
This is done by removal of the disc [discectomy] or removal of vertebra[corpectomy or vertebrectomy] depending upon the extent of bony injury and comminution and cause of compression as decide preoperatively with help of imaging studies.
Anterior Reduction of Dislocated Facets
If there is additional disc herniation, an anterior discectomy and decompression may be performed before reduction. he dislocation is reduced by maneuvering the dislocated facets by leverage on the vertebral body so as to unlock the vertebrae.
A lateral intraoperative x-ray should be obtained to confirm reduction.
If the dislocation is not reducible an additional posterior surgery might be done.
Reconstruction is done for replacement of the removed vertebra or disc. Autograft or allograft bone can be used to reconstruct the anterior column. Another alternative is the insertion of a titanium mesh cage.
Following reconstruction, anterior stabilization should be performed spanning discectomy or corpectomy defects.
The posterior approach to the cervical spine is a midline extensile approach that can be used to access as many spinal levels as necessary.
In the majority of acute, traumatic, injuries, posterior decompression is not necessary.In rare cases of anteriorly displaced posterior arch fragments, a laminectomy would be indicated to directly remove the offending compressive elements.
Usually, the primary goal of posterior surgery for subaxial cervical injuries is reduction or stabilization. Open reduction of dislocated facet joints can be performed using a posterior approach.
The options available are wire-based constructs, variable-angle screw-rod constructs.
Cancellous bone harvested from the posterior iliac crest is packed inside curetted the facet joints for the purpose of fusion.
Rigid internal fixation reduces the postoperative external immobilization which varies from individual to individual. Prophylactic antibiotics are continued for 48 hours or more if required.
Cervical Injuries in Spondylosis
Patients with the ankylosed and spondylotic spine can suffer cervical injury even after minor trauma. Therefore, the patients who present with neck pain or neurologic deficit after major or minor trauma should be considered to have a cervical spine injury until proven otherwise.
Degenerative spondylotic changes, such as vertebral body osteophytes, fixed subluxations, and facet hypertrophy can make plain films difficult to interpret. Therefore unless the injury is severe, the plain x-rays may not be helpful in detecting a level of injury.
If x-rays do not reveal much information CT or MRI should be done in these patients.
Two situations warrant more discussion
- Fractures in patients with ankylosing spondylitis and diffuse idiopathic skeletal hyperostosis
- Spinal cord injuries in patients with cervical spondylosis without ligamentous or bony instability.
Fractures with Ankylosing Spondylitis and Diffuse Idiopathic Skeletal Hyperostosis
Due to ankylosis, the spine can no longer be considered as constituted of multiple motion segments. Instead, the ankylosed spine should be considered as a long bone.
Bridging osteophytes in these diseases fuse the spine into a solid, continuous piece of bone. If there is a break in one region, it is likely to have propagated through both the anterior and posterior elements. Therefore any fracture in the cervical spine in these patients should be considered as unstable and treated accordingly.
Patients should be immobilized as soon as the diagnosis is made, admitted, and placed on strict log-roll precautions until definitive management.
Halo fixation, anterior fixation, and posterior fixation are the treatment options in these patients through optimal treatment has not yet been formulated in the literature.
Spinal Cord Injury In Spondylotic Spine
There is an underlying cervical stenosis in these patients following the degenerative changes which increase the risk for neural injury.
Patients often present with complete or incomplete spinal cord injury without x-ray signs. CT or MRI as desired may be asked
Again there is a shortage of data on what is optimal treatment.
It includes rest, collar immobilization and observation in particular for patients with central cord lesions, in which a high percentage will have a nearly complete resolution of their neural deficits. The decision for long-term definitive treatment is influenced by the presence of persistent signs or symptoms or myelopathy.
Those patients who have an unstable spine or do not recover are treated with surgery. The treatment depends on cervical injury level and the presence or absence of myelopathy.
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