Orthopaedic Trauma Association Classification of Cervical Spine Injuries

See Fracture and Dislocation Classification Compendium at:http://www.ota.org/compendium/compendium.html

Occipital Condyle Fractures

• These are frequently associated with C1 fractures as well as cranial nerve palsies.
• The mechanism of injury involves compression and lateral bending; this causes either compression fracture of the condyle as it presses against the superior facet of C1 or avulsion of the alar ligament with extremes of atlantooccipital rotation.
• CT is frequently necessary for diagnosis.

Occipitoatlantal Dislocation (Craniovertebral Dissociation)

• This is almost always fatal, with postmortem studies showing it to be the leading cause of death in motor vehicle accidents; rare survivors have severe neurologic deficits ranging from complete C1 flaccid quadriplegia to mixed incomplete syndromes such as Brown-Séquard.
• This is twice as common in children, owing to the inclination of the condyles.
• It is associated with submental lacerations, mandibular fractures, and posterior pharyngeal wall lacerations.
• It is associated with injury to the cranial nerves (the abducens and hypoglossal nerves are most commonly affected by craniocervical injuries), the first three cervical nerves, and the vertebral arteries.
• The cervicomedullary syndromes, which include cruciate paralysis as described by Bell and hemiplegia cruciata initially described by Wallenberg, represent the more unusual forms of incomplete spinal cord injury and are a result of the specific anatomy of the spinal tracts at the junction of the brainstem and spinal cord. Cruciate paralysis can be similar to a central cord syndrome, although it normally affects proximal more than distal upper extremity function. Hemiplegia cruciata is associated with ipsilateral arm and contralateral leg weakness.
• Mechanism is a high-energy injury resulting from a combination of hyperextension, distraction, and rotation at the craniocervical junction.
• The diagnosis is often missed, but it may be made on the basis of the lateral cervical spine radiograph:
  • The tip of odontoid should be in line with the basion.
  • The odontoid–basion distance is 4 to 5 mm in adults and up to 10 mm in children.
  • Translation of the odontoid on the basion is never >1 mm in flexion/extension views.
  • Powers ratio (BC/OA) should be <1 (Fig. 9.5).
  • In adults, widening of the prevertebral soft tissue mass in the upper neck is an important warning sign of significant underlying trauma and may be the only sign of this injury.
  • Fine-cut CT scans with slices no more than 2 mm wide are helpful to understand articular incongruities or complex fracture patterns more clearly. MRI of the craniovertebral junction is indicated for patients with spinal cord injury and can be helpful to assess upper cervical spine ligamentous injuries as well as subarachnoid and prevertebral hemorrhage.
• Classification based on the position of the occiput in relation to C1 is as follows:
  • Type I: Occipital condyles anterior to the atlas; most common
  • Type II: Condyles longitudinally dissociated from atlas without translation; result of pure distraction
  • Type III: Occipital condyles posterior to the atlas
• The Harborview classification attempts to quantify stability of craniocervical junction. Surgical stabilization is reserved for type II and III injuries.
  • Type I: Stable with displacement <2 mm
  • Type II: Unstable with displacement <2 mm
  • Type III: Gross instability with displacement >2 mm
• Immediate treatment includes halo vest application with strict avoidance of traction. Reduction maneuvers are controversial and should ideally be undertaken with fluoroscopic visualization.
• Long-term stabilization involves fusion between the occiput and the upper cervical spine.

Atlas Fractures

• These are rarely associated with neurologic injury.
• Instability invariably equates to the presence of transverse alar ligament insufficiency, which can be diagnosed either by direct means, such as by identifying bony avulsion on CT scan or ligament rupture on MRI, or indirectly by identifying widening of the lateral masses.
• Fifty percent of these injuries are associated with other cervical spine fractures, especially odontoid fractures and spondylolisthesis of the axis.
• Cranial nerve lesions of VI to XII and neurapraxia of the suboccipital and greater occipital nerves may be associated.
• Vertebral artery injuries may cause symptoms of basilar insufficiency such as vertigo, blurred vision, and nystagmus.
• Patients may present with neck pain and a subjective feeling of “instability.”
• The mechanism of injury is axial compression with elements of hyperextension and asymmetric loading of condyles causing variable fracture patterns.
• Classification (Levine) (Fig. 9.6)
  • Isolated bony apophysis fracture
  • Isolated posterior arch fracture
  • Isolated anterior arch fracture
  • Comminuted lateral mass fracture
  • Burst fracture, also known as the Jefferson fracture
• Treatment
  • Initial treatment includes halo traction/immobilization.
  • Stable fractures (posterior arch or nondisplaced fractures involving the anterior and posterior portions of the ring) may be treated with a rigid cervical orthosis.
  • Less stable configurations (asymmetric lateral mass fracture with “floating” lateral mass, burst fractures) may require prolonged halo immobilization.
  • C1–C2 fusion may be necessary to alleviate chronic instability and/or pain.

Transverse Ligament Rupture (Traumatic C1–C2 Instability)

• This rare, usually fatal, injury is seen mostly in older age groups (50s to 60s).
• The mechanism of injury is forced flexion.
• The clinical picture ranges from severe neck pain to complete neurologic compromise.
• Rupture of the transverse ligament may be determined by:
  • Visualizing the avulsed lateral mass fragment on CT scan
  • Atlantoaxial offset >6.9 mm on an odontoid radiograph
  • ADI >3 mm in adults. An ADI >5 mm in adults also implies rupture of the alar ligaments.
  • Direct visualization of the rupture on MRI
• Treatment
  • Initial treatment includes halo traction/immobilization.
  • In the cases of avulsion, halo immobilization is continued until osseous healing is documented.
  • C1–C2 fusion is indicated for tears of the transverse ligament without bony avulsion, chronic instability, or pain (Fig. 9.7).

Atlantoaxial Rotary Subluxation and Dislocation

• In this rare injury, patients present with confusing complaints of neck pain, occipital neuralgia, and, occasionally, symptoms of vertebrobasilar insufficiency. In chronic cases, the patient may present with torticollis.
• It is infrequently associated with neurologic injury.
• The mechanism of injury is flexion/extension with a rotational component, although in some cases, it can occur spontaneously with no reported history of trauma.
• Odontoid radiographs may show asymmetry of C1 lateral masses with unilateral facet joint narrowing or overlap (wink sign). The C2 spinous process may be rotated from the midline on an AP view.
• The subluxation may be documented on dynamic CT scans; failure of C1 to reposition on a dynamic CT scan indicates fixed deformity.
• Classification (Fielding)
  • Type I: Odontoid as a pivot point; no neurologic injury; ADI <3 mm; transverse ligament intact (47%)
  • Type II: Opposite facet as a pivot; ADI <5 mm; transverse ligament insufficient (30%)
  • Type III: Both joints anteriorly subluxed; ADI >5 mm; transverse and alar ligaments incompetent
  • Type IV: Rare; both joints posteriorly subluxed
  • Type V: Levine and Edwards: frank dislocation; extremely rare
• Treatment
  • Cervical halter traction in the supine position and active range-of-motion exercises for 24 to 48 hours initially are followed by ambulatory orthotic immobilization with active range-of-motion exercises until free motion returns.
  • Rarely, fixed rotation with continued symptoms and lack of motion indicates a C1–C2 posterior fusion.

Fractures of the Odontoid Process (Dens)

• A high association exists with other cervical spine fractures.
• There is a 5% to 10% incidence of neurologic involvement with presentation ranging from Brown-Séquard syndrome to hemiparesis, cruciate paralysis, and quadriparesis.
• Vascular supply arrives through the apex of the odontoid and through its base with a watershed area in the neck of the odontoid.
• High-energy mechanisms of injury include motor vehicle accident or falls with avulsion of the apex of the dens by the alar ligament or lateral/oblique forces that cause fracture through the body and base of the dens.
• Classification (Anderson and D’Alonzo) (Fig. 9.8)
  • Type I: Oblique avulsion fracture of the apex (5%)
  • Type II: Fracture at the junction of the body and the neck; high nonunion rate, which can lead to myelopathy (60%)
  • Type III: Fracture extending into the cancellous body of C2 and possibly involving the lateral facets (30%)
• Subclassification of type II odontoid fractures based on fracture obliquity and displacement. They further clarified the type II fracture as any fracture that does not extend into the C1–C2 facet articulation, even if it involves a portion of the body of C2.
  • Type IIA: Minimally or nondisplaced fracture with no comminution
  • Type IIB: Displaced fracture with superior to posterior–inferior oblique fracture line
  • Type IIC: Displaced fracture with anterior–inferior to posterior–superior oblique fracture line
• Treatment
  • Type I: If it is an isolated injury, stability of the fracture pattern allows for immobilization in cervical orthosis.
  • Type II: This is controversial because the lack of periosteum and cancellous bone and the presence in watershed area result in a high incidence of nonunion (36%). Risk factors include age >50 years, >5-mm displacement, and posterior displacement. It may require screw fixation of the odontoid or C1–C2 posterior fusion for adequate treatment. Nonoperative treatment is halo immobilization. Type IIB fractures are more amenable to anterior screw fixation. The obliquity of the fracture line in type IIC are less amenable to the lag technique of anterior screw fixation.
  • Type III: There is a high likelihood of union with halo immobilization owing to the cancellous bed of the fracture site.

C2 Lateral Mass Fractures

• Patients often present with neck pain, limited range of motion, and no neurologic injury.
• The mechanisms of injury are axial compression and lateral bending.
• CT is helpful for diagnosis.
• A depression fracture of the C2 articular surface is common.
• Treatment ranges from collar immobilization to late fusion for chronic pain.

Traumatic Spondylolisthesis of C2 (Hangman’s Fracture)

• This is associated with a 30% incidence of concomitant cervical spine fractures. It may be associated with cranial nerve, vertebral artery, and craniofacial injuries.
• The incidence of spinal cord injury is low with types I and II and high with type III injuries.
• The mechanism of injury includes motor vehicle accidents and falls with flexion, extension, and axial loads. This may be associated with varying degrees of intervertebral disc disruption. Hanging mechanisms involve hyperextension and distraction injury, in which the patient may experience bilateral pedicle fractures and complete disruption of disc and ligaments between C2 and C3.
• Classification (Levine and Edwards; Effendi) (Fig. 9.9)
  • Type I: Nondisplaced, no angulation; translation <3 mm; C2–C3 disc intact (29%); relatively stable
  • Type IA: Atypical unstable lateral bending fractures that are obliquely displaced and usually involve only one pars interarticularis, extending anterior to the pars and into the body on the contralateral side
  • Type II: Significant angulation at C2–C3; translation >3 mm; most common injury pattern; unstable; C2–C3 disc disrupted (56%); subclassified into flexion, extension, and olisthetic types
  • Type IIA: Avulsion of entire C2–C3 intervertebral disc in flexion with injury to posterior longitudinal ligament, leaving the anterior longitudinal ligament intact; results in severe angulation; no translation; unstable; probably caused by flexion–distraction injury (6%); traction contraindicated
  • Type III: Rare; results from initial anterior facet dislocation of C2 on C3 followed by extension injury fracturing the neural arch; results in severe angulation and translation with unilateral or bilateral facet dislocation of C2–C3; unstable (9%); type III injuries most commonly associated with spinal cord injury: frank dislocation; extremely rare
• Treatment
  • Type I: This usually requires rigid cervical orthosis for up to 6 weeks.
  • Type II: This is determined by stability; it usually requires halo traction/immobilization with serial radiographic confirmation of reduction for at least 6 weeks.
  • Type IIA: Traction may exacerbate the condition; therefore, only immobilization may be indicated.
  • Type III: Initial halo traction is followed by open reduction and posterior fusion of C2–C3, with fracture fixation and/or possible anterior fusion.

Classification (Allen-Ferguson)

• Compressive flexion (shear mechanism resulting in “teardrop” fractures) (Fig. 9.10)
  • Stage I: Blunting of anterior body; posterior elements intact
  • Stage II: “Beaking” of the anterior body; loss of anterior vertebral height
  • Stage III: Fracture line passing from anterior body through the inferior subchondral plate
  • Stage IV: Inferoposterior margin displaced <3 mm into the neural canal
  • Stage V: “Teardrop” fracture; inferoposterior margin >3 mm into the neural canal; failure of the posterior ligaments and the posterior longitudinal ligament
• Vertical compression (burst fractures) (Fig. 9.11)
  • Stage I: Fracture through the superior or inferior endplate with no displacement
  • Stage II: Fracture through both endplates with minimal displacement
  • Stage III: Burst fracture; displacement of fragments peripherally and into the neural canal
• Distractive flexion (dislocations) (Fig. 9.12)
  • Stage I: Failure of the posterior ligaments, divergence of the spinous processes, and facet subluxation
  • Stage II: Unilateral facet dislocation; translation always <50%
  • Stage III: Bilateral facet dislocation; translation of 50% and “perched” facets
  • Stage IV: Bilateral facet dislocation with 100% translation
• Compressive extension (Fig. 9.13)
  • Stage I: Unilateral vertebral arch fracture
  • Stage II: Bilateral laminar fracture without other tissue failure
  • Stages III, IV: Theoretic continuum between stages II and V
  • Stage V: Bilateral vertebral arch fracture with full vertebral body displacement anteriorly; ligamentous failure at the posterosuperior and anteroinferior margins
• Distractive extension (Fig. 9.14)
  • Stage I: Failure of anterior ligamentous complex or transverse fracture of the body; widening of the disc space and no posterior displacement
  • Stage II: Failure of posterior ligament complex and superior displacement of the body into the canal
• Lateral flexion (Fig. 9.15)
  • Stage I: Asymmetric, unilateral compression fracture of the vertebral body plus a vertebral arch fracture on the ipsilateral side without displacement
  • Stage II: Displacement of the arch on the AP view or failure of the ligaments on the contralateral side with articular process separation
• Miscellaneous cervical spine fractures
  • “Clay shoveler’s” fracture: This is an avulsion of the spinous processes of the lower cervical and upper thoracic vertebrae. Historically, this resulted from muscular avulsion during shoveling in unyielding clay with force transmission through the contracted shoulder girdle. Treatment includes restricted motion and symptomatic treatment until clinical improvement or radiographic healing of the spinous process occurs.
  • Sentinel fracture: This fracture occurs through the lamina on either side of the spinous process. A loose posterior element may impinge on the cord. Symptomatic treatment only is indicated unless spinal cord compromise exists.
  • Ankylosing spondylitis: This may result in calcification and ossification of the ligamentous structures of the spine, producing “chalk stick” fractures after trivial injuries. These fractures are notoriously unstable because they tend to occur through brittle ligamentous structures. Attempts at reduction, or even repositioning the patient, may result in catastrophic spinal cord injury because the injury involves all three spinal columns. Treatment includes traction with minimal weight in neutral or the presenting position of the neck, with aggressive immobilization with either halo vest or open stabilization.
  • Gunshot injuries: Missile impact against bony elements may cause high-velocity fragmentation frequently associated with gross instability and complete spinal cord injury. Surgical extraction of missile fragments is rarely indicated in the absence of canal compromise. Missiles that traverse the esophagus or pharynx should be removed, with aggressive exposure and debridement of the missile tract. These injuries carry high incidences of abscess formation, osteomyelitis, and mediastinitis.

Initial Treatment

• Immobilization with a cervical orthosis (for stable fractures) or skull traction (for unstable injuries) should be maintained in the emergency setting before CT for evaluation of spinal and other system injuries. Skull or skeletal traction may be applied using Gardner-Wells tongs or preferably by application of a halo crown, which can be used for traction and subsequently attached to a vest assembly (halo vest).
• Vasopressor support is indicated for suspected neurogenic shock and emergency assessment for potential intracranial trauma.
• Use of intravenous methylprednisolone per the National Acute Spinal Cord Injury Study (NASCIS) II and III protocol (30 mg/kg loading dose and then 5.4 mg/kg for 24 hours if started within 3 hours, for 48 hours if started within 8 hours; steroids have no benefit if they are started more than 8 hours after injury) is controversial and is no longer considered the “standard of care” (see Chapter 8).
• The majority of cervical spine fractures can be treated nonoperatively. The most common method of nonoperative treatment is immobilization in a cervical orthosis. In reality, orthoses decrease motion rather than effect true immobilization. Motion at the occipital–cervical junction is slightly increased by most cervical collars.
  • Soft cervical orthosis: This produces no significant immobilization and is a supportive treatment for minor injuries.
  • Rigid cervical orthosis (Philadelphia collar): This is effective in controlling flexion and extension; however, it provides little rotational or lateral bending stability.
  • Poster braces: These are effective in controlling midcervical flexion, with fair control in other planes of motion.
  • Cervicothoracic orthoses: These are effective in flexion and extension and rotational control, with limited control of lateral bending.
  • Halo device: This provides the most rigid immobilization (of external devices) in all planes.
  • For traction, Gardner-Wells tongs are applied one finger’s width above the pinna of the ear in line with the external auditory canal. Slight anterior displacement will apply an extension force, whereas posterior displacement will apply a flexion force, useful when reducing facet dislocations (Fig. 9.16).
  • Numerous complications are associated with the use of cervical collars. Skin breakdown at bony prominences, in particular, the occiput, mandible, and sternum, can occur. Up to 38% of patients with severe closed head injuries can develop skin complications with prolonged use.
• Patients with neural deficits from burst-type injuries: Traction is used to stabilize and indirectly decompress the canal via ligamentotaxis.
• Patients with unilateral or bilateral facet dislocations and complete neural deficits: Gardner-Wells tong traction and reduction by sequentially increasing the amount of traction are indicated. Radiographs must be performed after the first 10 lb of weight is applied to rule out occult occipital–cervical dislocation. The weight is increased in 5-lb increments with radiographs obtained after each increase.
• Traction is contraindicated in distractive cervical spine injuries and type IIA spondylolisthesis injuries of C2.
• Patients with incomplete neural deficits or who are neurologically intact with unilateral and bilateral facet dislocations require MRI before reduction via traction to evaluate for a herniated disc, especially if a patient is not awake and alert and able to cooperate with serial examinations during reduction maneuvers. Although controversial, some authors recommend immediate traction reduction in the awake patient with an incomplete spinal cord injury if the patient can cooperate with serial exams so that no time is lost getting an MRI.
• A halo has been recommended for patients with isolated occipital condyle fractures, unstable atlas ring fractures, odontoid fractures, and displaced neural arch fractures of the axis.
• The halo vest relies on a firm fit of the vest around the torso and is poorly tolerated by elderly patients and patients with pulmonary compromise or thoracic deformities, such as those with ankylosing spondylitis.
• The halo ring should be applied 1 cm above the ears. Anterior pin sites should be placed below the equator of the skull above the supraorbital ridge, anterior to the temporalis muscle, and over the lateral two-thirds of the orbit. Posterior sites are variable and are placed to maintain horizontal orientation of the halo. Pin pressure should be 6 to 8 lb in the adult and should be retightened at 24 hours. Pin care is optional.
• Prolonged recumbence carries an increased morbidity and mortality risk, and consideration should be given to the use of a RotoRest bed and mechanical as well as pharmacologic thromboprophylaxis.
• Because of the normally wide spinal canal diameter, decompression of neural elements in upper cervical spine fractures is not commonly required for traumatic conditions.
• The optimal time to perform surgery, particularly in patients with neurologic deficits, remains unclear. The two most commonly proposed benefits of earlier versus later surgery are improved rates of neurologic recovery and improved ability to mobilize the patient without concern of spinal displacement. To date, little human clinical evidence supports the view that early surgical decompression and stabilization improve neurologic recovery rates. However, clinical series have demonstrated that surgery performed as soon as 8 hours after injury does not appear to increase the rate of complications or lead to neurologic decline.

Stabilization of the Upper Cervical Spine (Occiput–C2)

• The mainstay of operative treatment of upper cervical fractures and dislocations remains fusion with instrumentation, most commonly performed from the posterior approach. In order of frequency, the most common upper cervical fusion procedures are atlantoaxial fusion, occipitocervical fusion, and, least commonly, C1–C3 fusion.
• Fusion of the occiput–C2 limits 50% of flexion and extension.
• Fusion of C1–C2 limits 50% of rotation.

Stabilization of the Lower Cervical Spine (C3–C7)

• Fifty percent of flexion/extension and 50% of rotation are evenly divided between each of the facet articulations.
• Fusion of each level reduces motion by a proportionate amount.
• Posterior decompression and fusion
  • The posterior approach to the cervical spine is a midline, extensile approach that can be used to access as many spinal levels as necessary, with a variety of instrumentation techniques in use.
  • In the majority of acute, traumatic, subaxial spinal injuries, posterior decompression via laminectomy is not necessary. Canal compromise is most frequently caused by dislocation, translation, or retropulsed vertebral body fragments. In rare cases of anteriorly displaced posterior arch fragments, laminectomy would be indicated to directly remove the offending compressive elements. This is not true, however, in cases of acute spinal cord injury associated with multilevel spondylotic stenosis or ossification of the posterior longitudinal ligament, in which a posterior decompressive procedure may be considered the procedure of choice if cervical lordosis has been maintained.
  • Open reduction of dislocated facet joints is typically performed using a posterior approach.
• Posterior cervical fusion and instrumentation with lateral mass fixation
  • This can be utilized for a variety of fractures including facet fractures, facet dislocations, and “teardrop” (compressive flexion stage V) fractures.
  • Single-level fusions are sufficient for dislocations, although multilevel fusions may be required for more unstable patterns.
  • This can stop fusion at levels with fractured spinous processes or laminae, thus avoiding the fusion of extra levels with consequent loss of motion.
• Anterior decompression and fusion
  • These are used for vertebral body burst fractures with spinal cord injury and persistent anterior cord compression.
  • The anterior approach to the subaxial spine utilizes the interval plane between the sternocleidomastoid (lateral) and anterior strap (medial) muscles. Deeper, the interval of dissection is between the carotid sheath laterally and the trachea/esophagus medially.
  • MRI, myelography, and CT are valuable in preoperative assessment of bony and soft tissue impingement on the spinal cord.
  • A simple discectomy or corpectomy in which osseous fragments are removed from the canal and a tricortical iliac or fibular graft placed between the vertebral bodies by a variety of techniques can be performed.
  • In the presence of a herniated cervical disc associated with dislocated facet joints, one may elect to perform an anterior discectomy and decompression with or without corpectomy before facet reduction.
  • Anterior plating or halo vest immobilization adds stability during healing.