The cervical region of the spinal column is the most frequently involved in trauma, accounting for over half of all spine injuries. Injury to the cervical spine is most commonly caused by motor vehicle accidents and by falls from a height and diving accidents. The most frequent mechanism of injury is axial compression. Some 20 per cent of these patients are hypotensive upon arrival in the emergency department, and up to 30 per cent have associated intraperitoneal or severe pelvic or extremity trauma.

Evaluation and stabilization of these patients must proceed in an organized and stepwise fashion. The establishment of the basic requirements (airway, breathing, and circulation) must be accompanied by stabilization of the cervical spine either with an appropriate collar or by other means of immobilization. Following the initial review the patient and/or rescue personnel are questioned regarding the mechanism of injury, the position of the head and neck at the time of injury, loss of consciousness, presence of neck pain, and any neurological symptoms. A comprehensive physical examination should specifically look for signs of head and neck trauma and the presence of neck pain, and a complete neurological review should be clearly documented in the patient's chart.

Screening radiographs should be obtained in all patients with suspected cervical injury. These should consist of a lateral view that shows the C7 - T1 junction clearly, as well as anteroposterior and odontoid views. Oblique projections may also be helpful in the initial evaluation. On the lateral film systematic inspection of the soft tissues for prevertebral swelling should alert the clinician to possible spine injury (Fig. 1) 2489. The overall alignment of the vertebral bodies, neural canal, and spinous processes should be evaluated, looking for abnormal angulation or displacement. In certain injuries additional studies may be required to define clearly the extent of the injury. Plain radiographs may be supplemented with dynamic studies such as flexion/extension or traction views. Both of these tests require a conscious and alert patient. In no circumstance should they be performed on an unconscious subject.

Computerized axial tomography (CT) with or without three-dimensional reconstruction and linear tomography may aid in the delineation of bony vertebral injury. Fractures of the dens, facet fractures and/or dislocations, and laminar fractures are better visualized on lateral tomography than they are on conventional CT scans. Magnetic resonance imaging (MRI) and myelography with CT scan are reliable methods for evaluating the spinal cord. These methods may be most helpful in evaluating the patient with obvious cord injury and no radiographic evidence of fracture, an injury which occurs in approximately 10 per cent of cases with cervical spine trauma. Magnetic resonance imaging holds the specific advantage of allowing visualization of disease within the substance of the cord as may occur in patients with cervical spondylosis and a central cord syndrome. However, MRI may not be able to detect haematoma within the first 6 to 24 h after injury. As a general rule displaced and angulated fractures should be treated with immediate application of traction. Skull tongs or halo traction is the preferred method. The rule of thumb is to start with 2.25 kg (5 lb) of weight per level of injury allowing 3 kg (7 lb) for the weight of the head. With this guideline a C5 - C6 injury would be initially treated with 13.5 to 16 kg of traction (30 - 35 lb). The reduction of the deformity should start with less than maximal weight and should be incrementally increased. This process should be followed closely with repeat clinical and radiographic examination. Overdistraction has the potential for increased injury to the cord and should be strictly avoided. Immediate improvement in neurological status may be seen with just postural reduction and traction. Definitive treatment depends on the type and level of injury which can be broadly separated into the upper (occipital condyles to C2) and lower (C3 to C7) cervical spine.

Injury to this region of the cervical spine is rare. This does not necessarily indicate that these injuries occur infrequently, but rather that they are not always recognized. These injuries are frequently accompanied by severe head trauma; more often than not they are fatal. Patients may have coma and respiratory arrest.

Axial load to the top of the head with lateral bend may result in unilateral condyle fractures. These fractures may also present with cranial nerve injuries. A hyperextension mechanism, on the other hand, may lead to atlanto-occipital dislocation (Fig. 2) 2490.

Depending on the injury, radiographic evaluation may reveal fractures through the temporal bone, prevertebral soft tissue swelling, and obvious malalignment between the occiput and the ring of the atlas. Occipitoatlantal dislocation injuries may be assessed on radiographic criteria described by Powers. In patients with stable fracture of the condyle(s) the management should consist of immobilization in an orthotic support for a period of 6 to 8 weeks. Following this the spine should be evaluated for signs of instability and occiput to C1 or C2 fusion undertaken if indicated. Purely ligamentous disruption at the atlanto-occipital junction requires more aggressive treatment. For the initial treatment and stabilization the use of skeletal traction is advocated by some authors. However, there is the real possibility of overdistracting the cord and brain-stem and exacerbating the neurological injury. Recognizing that ligamentous disruptions usually do not heal with adequate stability, this injury is best treated with occiput to C1 or C2 fusion.

Fractures of the first cervical vertebra account for one-quarter of all injuries at the atlantoaxial junction and for 10 per cent of all cervical spine fractures.

The first type of atlas fracture is that of the posterior arch. In 50 to 60 per cent of cases this fracture is associated with either a fracture of C2 or a more caudal level of the cervical or even upper thoracic spine. This injury is caused by a hyperextension mechanism. Isolated posterior arch fractures are stable injuries which may be treated effectively with orthotic immobilization. If multiple level fractures are present then the treatment plan must be tailored accordingly.

The second fracture pattern produces unilateral fracture lines anterior and posterior to the articular surface of the lateral mass. The fracture lines may transgress the articular surface, and also may include an osteoperiosteal avulsion of the transverse ligament. The open mouth odontoid view shows the pathognomonic lateral displacement of one articular mass (Fig. 3) 2491,2492,2493. This fracture is produced by an asymmetric axial loading with the head tilted to the side of injury. Intra-articular fracture with avulsion of the transverse ligament may predispose to symptomatic non-union. Nonetheless, if there is only minimal displacement of the fragments (less than 7 mm) these fractures may be effectively treated with halo immobilization. Dynamic studies should be used to exclude instability at the conclusion of treatment.

The third type is the Jefferson fracture, which involves fracture of the ring at four points. This is also referred to as a burst fracture pattern. Neurological involvement is rare since the space available for the cord is effectively increased by the fracture pattern. Controversies that surround this particular injury centre on the issue of instability. Since the ring of the atlas is fractured at four points, the lateral masses are free to be displaced laterally. Lateral displacement of more than 7 mm corresponds to rupture of the transverse ligament leading to flexion - extension instability between C1 and C2. However, this instability is usually less then 5 mm and is not important. Treatment of these injuries may consist of a course of traction, the benefit of which is reduction of the displaced fragments. If traction is not continued for at least 6 weeks, however, the reduction is usually lost. Following a course of traction these patients are usually maintained in a halo vest for up to 3 months. If after non-operative management instability greater than 5 mm is still present, late surgical stabilization may be undertaken.

There have been several names appended to purely ligamentous injury of the atlantoaxial joint including rotary subluxation, rotary dislocation, and rotary fixation. This injury is most commonly encountered in victims of motor vehicle accidents. Patients typically have neck pain and spasm and may have an associated torticollis deformity. The diagnosis can be made with the help of open mouth odontoid views, anteroposterior tomograms, and transverse CT scans. However, a high level of awareness is necessary to prevent missed diagnosis. Typically these injuries go untreated for weeks to months. The associated symptoms are pain, stiffness, spasm, and, very rarely, neurological deficit. Treatment calls for axial traction in an effort to reduce the subluxation. Once reduction is achieved, the patient is maintained in halo vest immobilization for up to 3 months. Since these injuries are purely ligamentous, evaluation for instability after removal of the halo is mandatory. In patients with a delayed recognition of their problem surgical stabilization after attempted reduction is recommended.

The classification scheme that is used by most surgeons for treatment and prognostication is that devised by Anderson and D'Alonzo (Fig. 4) 2494,2495,2496. In a series of almost 1500 cervical spine fractures there was a 6 to 14 per cent incidence of odontoid fractures. Meyer's incidence of fracture types was: 12 per cent type I, 69 per cent type II, 19 per cent type III. In general these fractures may be readily visualized on plain lateral, oblique, and open-mouth odontoid views. Lateral tomograms and sagittal reconstruction CT scans may be helpful.

Type I is an oblique fracture through the tip of the odontoid. This probably represents an avulsion injury of the alar or apical ligaments at the tip of the dens and is felt to be a stable and clinically insignificant injury. These patients may be treated symptomatically with a cervical collar.

The most common and most controversial odontoid fracture is the type II or waist fracture. As described by Anderson and D'Alonzo this fracture occurs at the junction of the odontoid process with the body of the second cervical vertebra. Mouradian proposed a lateral bending mechanism for these injuries. The controversy surrounding this fracture centres on the issue of treatment and avoidance of non-union. Factors implicated in non-union are disruption of the vascular supply to the dens, fracture displacement greater than 5 mm or angulation greater the 10°, patient age, and fractures occurring higher on the waist of the dens.

Fracture healing also appears to be related to the method of treatment. Conservative management yields a 20 to 80 per cent rate of union. A 100 per cent non-union rate follows untreated or orthosis-managed type II fractures. Patients treated in halo vest have a 70 per cent rate of stable union while posterior cervical fusion yields 96 per cent stable union. Patients with significantly displaced or angulated fractures or those with high waist fractures should be considered for early surgical stabilization. Posterior atlantoaxial fusion seems to be the most reliable approach.

Patients who sustain non-displaced, non-angulated, or minimal displaced fractures and impaction type injuries, where the dens is driven into the body of C2, may be treated with 3 months of halo vest immobilization. Post-halo assessment of instability is mandatory.

Type III fractures are slightly more straightforward injuries compared with type II. This fracture extends into the body of the axis, usually involving an anterior oblique fragment. Criteria for displacement are not so stringently worked out as they are in the type II fracture. These injuries have a higher rate of union, given the greater cancellous surface at the fracture site. Non-union rate for conservatively treated type III fractures, however, is still 10 to 13 per cent.

Bipedicular neural arch fracture of C2 is also called ‘hangman's fracture’. Several classification system have evolved. In Meyer's series hangman's fractures represent 12 per cent of all cervical spine injuries. Plain radiographs are usually sufficient for diagnosis, but tomograms and CT scans may be helpful for treatment planning. Neurological involvement seems to be predominantly limited to the severely displaced type III fracture.

Several factors are responsible for the differing constellation of injuries that occur in this region of the spine compared with the occipitoatlantoaxial complex. First the anatomy and articulation of the remaining five cervical vertebral bodies are relatively uniform. Each level or functional spinal unit is held together by the intervertebral disc, anterior and posterior longitudinal ligaments, the facet joints and capsules, and the remaining posterior column ligaments (supraspinous and interspinous ligaments, ligamentum flavum). Furthermore the neural canal diameter decreases (average 17 mm) thereby decreasing the canal-to-cord ratio and increasing the propensity to neurological damage.

As in more cephalad portions of the spine, stability is a prime concern in deciding on a treatment plan. Injuries to the lower cervical spine can be conveniently divided on the basis of anterior and posterior columns. The posterior column injuries involve the spinous processes, lamina, facet joints, and pedicles. The anterior column, composed of the vertebral body and disc, encompasses simple wedge and burst fractures, teardrop fractures, and disc disruptions. This demarcation is made only for the ease of categorization and does not imply that injury is limited exclusively to one column or the other.

The finding of avulsion fractures at the spinous process may indicate a hyperflexion or hyperextension injury. The fracture line in the hyperflexion injury is oblique and is felt to be the result of violent avulsion by the posterior paraspinal musculature. This fracture pattern is also known as ‘clay shoveller’ fracture. Widening of the interspinous space in these situations indicates a more extensive ligamentous injury. It is prudent to obtain dynamic studies in these patients once their paraspinal muscle spasm has resolved. In the interim they should be protected with a rigid collar. Definitive treatment in these cases is immobilization with Philadelphia collar immobilization for 3 to 6 weeks.

Unilateral injury to the facet joint usually results from a flexion - rotation mechanism. The amount of energy absorbed and direction of the force determines whether a fracture or dislocation, or unilateral versus bilateral, injury results. A unilateral facet dislocation occurs in 5 per cent of cases. Radiographs reveal lateral shift of the involved spinous process on the anteroposterior film, the facet joints proximal to the level of injury may be hard to distinguish on the lateral view, and the injured level may show a ‘rabbit ears’ outline. The vertebral body at the dislocation level is usually anteriorly translated by one-third in unilateral dislocations and by 50 per cent in bilateral dislocations. Neurological involvement occurs in 70 per cent of patients and presents as either a ‘single nerve root syndrome’ or unilateral motor paralysis with contralateral loss of pain and temperature sense (Brown - Sequard syndrome). Management of these injuries requires immediate attempt at closed reduction with halo or tong traction. In the neurologically intact patient in whom closed reduction is successful, halo immobilization for 3 months is an option. If neurological injury is present, the first line of treatment again is traction. However, posterior wiring is recommended whether or not the closed reduction is successful. Failing non-operative reduction, open reduction and segmental fixation is recommended. The stabilization method most commonly employed is interspinous wiring with single level fusion.

Bilateral facet dislocations are counterparts to the ‘Chance’ type fractures in the thoracolumbar spine. These injuries result from a hyperflexion mechanism and imply severe and destabilizing disruption of all of the posterior ligamentous structures. Furthermore, these injuries have a high association with disc ruptures, a fact that must be borne in mind during reduction attempts. Neurological damage is found in over 90 per cent of patients, half of these being complete cord injuries.

Simple anterior compression fractures are the result of a flexion mechanism of injury. Several factors need to be addressed in the management of these injuries. If the amount of anterior compression, relative to uninjured vertebra above and below, is 25 per cent or less the injury is considered stable. The posterior vertebral wall as well as the posterior column ligaments must also be competent. If the injury is stable treatment may proceed with cervicothoracic orthotics for immobilization. If the lesion is unstable, posterior surgical stabilization is advised.

Flexion-axial load, as in diving accidents, leads to the burst fracture pattern. Along with severe comminution of the vertebral body these injuries are also accompanied by retropulsion of bone fragments into the vertebral canal, kyphotic angulation at the fracture, and varying degrees of posterior column ligamentous damage.

Given the potential for neural element injury from retropulsed fragments and angular displacement, it is not surprising that many of these patients present with complete neurological deficit. Initial management with traction can realign the angular deformity and also, through ligamentotaxis, may restore some neural canal volume. Patients with intact neurological status and minimal kyphotic deformity may be treated with halo immobilization. The concern in this situation is progressive deformity and the possibility for delayed neural damage. In patients with neurological compromise and unrelieved canal encroachment or severe kyphosis anterior decompression and strut grafting may be indicated.

A grossly unstable injury, the teardrop fracture results from a flexion - axial load mechanism. The vertebral body is fractured vertically, with the fracture line exiting through the disc space. In addition to disruption of the disc the posterior column ligamentous structures are also involved. Neurological injury is frequent and is explained by the amount of displacement that occurs at the time of injury.

Neurological injury without identifiable bony disease has been described in two distinct populations. In the adolescent or young adult participating in vigorous contact athletics, especially American football, this phenomenon is sometimes referred to as ‘burners’ or ‘stingers’. The neurological symptoms may vary from single extremity involvement to quadraplegia. Likewise the duration of symptoms ranges from minutes to as long as 48 h. Although this neurological injury is transient it can recur with repeat injury.

Bohler J. Anterior stabilization for acute fractures and non-unions of the dens. J Bone Joint Surg 1982; 64A: 18 - 27.

Clark CR, White AA. Fractures of the dens. J Bone Joint Surg 1985; 67A: 1340 - 8.

Levine AM. Cervical spine and cord: trauma. In: Lipson SJ, ed. Spine task force, Orthopaedic Knowledge Update 3. Park Ridge: American Academy of Orthopaedic Surgeons, 1990: 395 - 413.

Meyer PR. Surgery of spine trauma. New York: Churchill Livingstone, 1989.

Powers B, et al. Traumatic anterior atlanto-occipital dislocation. Neurosurgery 1979; 4: 12 - 17.

Segal LS, Grimm JO, Stauffer ES. Non-union of fractures of the atlas. J Bone Joint Surg 1987; 69A: 1423 - 34.

Stauffer ES, Kelly EG. Fracture-dislocations of the cervical spine. J Bone Joint Surgery 1977; 59A: 45 - 8.

Torg JS, et al. Neuropraxia of the cervical spinal cord with transient quadriplegia. J Bone Joint Surg 1986; 68A: 1354 - 70.

White AA, Panjabi MM. Update on the evaluation of the lower cervical spine. In Griffin PP, ed. Instructional Course Lectures. Park Ridge: American Academy of Orthopaedic Surgeons, 1987; 36: 499 - 520.