AUTHOR AND EDITOR INFORMATION

Section 1 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

INTRODUCTION

Section 2 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

The upper cervical spine is defined by the 2 most cephalad cervical vertebrae, C1 (the atlas) and C2 (the axis). This region is distinct in anatomic shape and is more mobile than the lower cervical spine, the subaxial cervical spine. The occipital condyles of the head (or the globe) rest upon the lateral masses of C1 (the atlas). These articular facets allow most of the flexion and extension of the head on the neck as the occipital condyles articulate on the atlas.

The ring of C1 has no vertebral body; the vertebral body that would correspond to C1 is connected or contiguous with the vertebral body of C2 and projects up as the dens (the tooth), also known as the odontoid of C2 (the axis). Most of the lateral rotation of the neck actually occurs at the C1-2 junction; the remaining motion of the cervical spine is distributed among the subaxial spine vertebral motion segments as a fractional amount (~7%) per level and is less in total than the C1-2 lateral rotation.

This area of the upper cervical spine is extremely mobile, and its stability is dependent on ligamentous structures. In unresponsive patients or those who are unable to report symptoms or pain, a C1 fracture or an occipital cervical dislocation must be excluded by radiographic screening. Also, displacement of the C1 ring may occur if the capsule or ligaments are disrupted, even without a C1 fracture; hence, the head may be displaced on the neck, and the atlas may also rotate around the odontoid or sustain a fracture of the dens.

History of the Procedure

Jefferson originally described this type of C1 fracture in 1920. The principal treatment is with a halo and vest or cast, which remains an effective current treatment for many of these fractures.

Problem

The C1 vertebra, or the atlas, is a closed ring. A fracture of a closed ring necessarily results in multiple areas (at least 2) of ring disruption. These disruptions are customarily accompanied by a spread of the C1 ring fragments as a result of the axial loading mechanism of this injury and the weight of the head. In addition to anteroposterior and lateral views, radiographs of the upper cervical spine include the open mouth view. The open mouth view may identify a spreading or widening of the lateral masses or an asymmetry of the separation of the odontoid from the lateral masses, which, in an appropriately centered radiograph, may be consistent with spreading of the C1 ring or a C1 fracture. An increased overhang of the lateral masses over the C2 facet totaling more than 6.9 mm suggests a fracture with disruption of the transverse odontoid ligament that may otherwise constrain displacement.

Fractures of the ring of C1 may be associated with an odontoid fracture; thus, the combination of the 2 fractures should be considered; furthermore, congenital anomalies of the arch (eg, agenesis of the posterior ring) may be present. Anterior subluxation of C1 on C2 may be present and, if so, often indicates a disruption of the transverse odontoid ligament.

Frequency

Fractures of the atlas compromise 25% of atlantoaxial complex bony injuries, 10% of cervical spine injuries, and 2% of all spine injuries. Injury to the cervical spine occurs infrequently in pediatric populations, and although C1 represents only 1-2% of pediatric trauma and 2-10% of all cervical injuries in this population, the associated mortality is 16%.

Etiology

The Jefferson fracture most commonly occurs as the result of axial loading on the head through the occiput, leading to a burst-type fracture of C1. Diving is the most frequent cause of this fracture, when it results from striking the head on an obstacle in shallow water; hence, the national program "Feet first, first time" (North American Spine Society, 2005) provides a motto for diving in unknown waters or shallow collections of water and has been an effective deterrent. The next most frequent cause of this fracture is being thrown up against the roof of a motor vehicle, a car or bus, or even an aircraft, and the forces are distributed to the body through the neck. The third most frequent cause of these injuries is falls onto the head, except in toddlers, who are predisposed to injury from falls because of their disproportionate head size.

Less frequenty, when a significant rotatory force is exerted, an atlantooccipital junction dislocation may occur or the force may also be dissipated through the odontoid as an associated fracture.

Pathophysiology

The ring of C1 is a structural member of the cervical spine. Because it is a ring and because fracture results in disruption of this ring, more than one location is affected. The fragments have a propensity to shift laterally from both the weight of the head and the muscular contraction acting through this articulation; thus, occipital condylar support for the head is lost. The absence of the rigid bony structure and the lack of interconnection or interrelation of the attached ligamentous structures meet the definition of instability, particularly as the bony protective function of C1 for the neural elements is lost.

Vertebral artery injuries have been reported as a result of C1 fractures, especially with atlantooccipital dislocations; small excursions of displacement can be fatal. In addition, vertebral artery injuries can occur and have been reported in the absence of severe trauma as a result of cervical traction, chiropractic manipulation, overhead work, or yoga exercises. Hyperextension is customarily accompanied with rotation; when this is not limited by normal restraints, it becomes excessive, severely diminishing blood flow through the vertebral arteries.

This diminished blood flow is particularly a problem in the posterior inferior cerebellar artery and may result in Wallenberg syndrome, which is characterized by ipsilateral loss of cranial nerves V, IX, X, and XI with cerebellar ataxia. Horner syndrome may occur and, in some cases, may involve contralateral loss of pain and temperature sensation; involvement can extend up from a lateral medullary infarct and spread to the basilar superior cerebellar or the inferior cerebral artery, leading to sudden death, quadriplegia, and the locked-in syndrome, in which quadriplegia occurs with loss of lower cranial nerves and only eye blinking is possible.

Clinical

Patients customarily present with a history of trauma and a symptom of pain in the neck. Amid the massive number of patients who qualify as having this history and symptom, a few patients have an unstable C1 injury and may present neurologically intact, but they are at grave risk for neurologic compromise if not promptly diagnosed and appropriately stabilized and treated.

Patients with a complete spinal cord injury and no neurologic function continue to have only sensation on the face and motor control of the facial muscles from the cranial nerves. A tracheostomy is essential because the patient requires respiratory assistance and a volume respirator. If the C3-5 area is intact, the phrenic nerve may often be stimulated to contract the diaphragm. If stimulation of the phrenic nerve does not contract the diaphragm, then the spinal cord is no longer functioning; the cell body is dead, and a phrenic electrical stimulator is not effective.

INDICATIONS

Section 3 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Recognition and identification of a Jefferson fracture is the indication to treat. Treatment consists of spinal stabilization to protect the patient from further nerve damage, including that to the brain stem. Children may represent less unstable cases, presumably because of periosteal stability, and they are often treated with a collar. The body of C1 is not visible radiographically until age 1 year.

Even in the absence of a C1 fracture, assessment of stability must include the associated structures. An atlantooccipital dislocation or disruption and C1-2 instability, particularly that in which the transverse ligament may be disrupted, poses severe risk to the brain stem and upper spinal cord. Furthermore, with a C1 fracture, associations exist with unstable injuries such as odontoid fractures and other injuries to the upper cervical spine. In addition, the odontoid fragment may migrate into the foramen magnum, endangering the brain stem and upper spinal cord.

The specific treatment should be based on analysis of the mechanism and extent of the injury. In a younger patient with limited displacement of the C1, immobilization with a collar or halo and vest may be adequate. In more severe cases, particularly with associated injuries such as odontoid fracture, bypassing the C1 ring with an occipital-to-cervical fusion extending to C2 or lower may be necessary. Instrumentation spanning that area may stabilize the C1 ring, which cannot be otherwise easily addressed directly, because both the anterior and posterior components of the ring are disconnected by the fracture and not amenable to instrumentation or direct repair.

RELEVANT ANATOMY

Section 4 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

The care of any fracture requires attention to the joint above and below; this cervical complex has often been treated as 2 separable articulations, C0-1 and C1-2, but the 3-unit occipitoatlantoaxial complex (C0-C1-C2) articulation is much more functionally relevant. The significance is the proximity to the brain, brain stem, and upper cervical spinal cord, but that is contrasted with the very significant motion that occurs in this area. Although patients are routinely asked to flex and extend their necks to determine range of motion, some of that motion observed is between the occiput and the atlas, and as the patient rotates laterally, at least 50% of that motion is atlantoaxial.

The stability of the injury depends on the ligaments between the bony structures. On the frontal view, the projecting occipital condyles are supported by the lateral masses (observed as wedges, narrow medially and expanding laterally), resting on the corresponding superior articular surface of the axis (C2). Consequently, the lateral masses provide inherent stability because of this bony shape and also illustrate the extent of the instability when this bony structure is disrupted, particularly when these wedges displace laterally.

The projecting condyles of the occiput are stabilized with the occipitoatlantal capsule, as well as anterior and posterior atlantooccipital membranes. The ligamentum nuchae is a significant stabilizing structure; its specific relevance to the atlantooccipital axial complex is controversial but should be considered. Connections from the occiput to the axis are the tectorium membrane and the alar and apical ligaments, which do not appear to be bulky enough to be independently significant restraints.

The dentate ligaments, consisting of the alar ligament and the apical ligaments, attach to the dorsal lateral surface of the dens and run obliquely to the medial surfaces of the occipital condyles. In a 1974 report, Anderson and D'Alonzo classified a type 1 odontoid fracture as an avulsion fracture of the tip of the odontoid caused by the apical ligament and suggested that some significant stability is imparted by these ligaments. A modified, treatment-oriented classification has been presented for odontoid fractures to expand the Anderson and D'Alonzo classification (Grauer et al, 2005), but acceptance or utility is too early to assess.

The transverse ligament goes from the medial surface of one side of the atlas to the other side and essentially constrains the axis to rotate around the odontoid in a closed ring of bone and the transverse ligament. As a consequence, the atlas can displace and embarrass the brain stem and spinal cord if this ligament ruptures or if an associated fracture of the odontoid is present as a result of this specific anatomic arrangement.

CONTRAINDICATIONS

Section 5 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

No significant contraindications to treatment exist, because the lack of stabilization, which commonly is initially provided either with traction or with a halo brace, can have fatal consequences. Any contraindications are mitigated by the potential for serious and even fatal neurologic consequences without treatment, as well as the fact that halo with vest or traction can be relatively effective in immobilizing the upper cervical spine, with low associated morbidity.

WORKUP

Section 6 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Imaging Studies

• Cervical spine radiographs are routinely obtained in the emergency department for patients with a history of pain or of trauma, and they are mandatory for the nonresponsive patient, who is unable to report pain.
• • These radiographs specifically include the open mouth view. After confirmation that neutral rotation is present and the radiograph is reliable (eg, as determined by looking at the incisor teeth to confirm lack of rotation of the head), the odontoid should appear as symmetrically centered between the lateral masses. A C1 fracture is often associated with lateral displacement, so if the ring of C1 overhangs or extends laterally more than 6.9 mm over the lateral mass, a fracture of the ring of C1 is established; however, less excursion does not exclude this fracture, particularly if minimally displaced in the supine patient.
  • The lateral view is also crucial because the atlantooccipital membranes may be disrupted and an occipitoatlantal dislocation may be observed; the normal anatomy must be confirmed. If any suspicion of disruption and/or dislocation exists, traction must be avoided, as well as any subsequent flexion-extension maneuvers or inappropriate manipulation, until that possibility can be excluded. The odontoid should be well imaged from the lateral view; any lack of alignment or discontinuity that suggests fracture also suggests instability of the upper cervical spine, which may be associated with a C1 fracture but indicates very significant instability, requiring immobilization of the occipitoatlantoaxial complex.

    On the lateral view, the Power ratio may be used to evaluate for possible atlantooccipital dislocation: a ratio greater than 1 of the basion to posterior arch of C1 (BC) over the anterior arch of C1 to the opisthion (AO) is suspicious for anterior dislocation

• If the ring is not clearly observed to overhang but asymmetry is present between the atlas and the odontoid, a C1-2 problem may be present, particularly atlantoaxial rotary subluxation, which may be a result of one of the facets between these 2 vertebrae being displaced or locked in a dislocated position. Unfortunately, a possible C1-2 instability, particularly the cock robin position of the head that may be present with displacement of C1 on one side (anteriorly is most common), makes obtaining the standard open mouth and other radiograph views difficult; CT scanning facilitates those investigations wherein thin cuts best demonstrate the pattern of disruption for evaluating the location and displacement of suspected fractures of C1. Unilateral posterior displacement of the atlas also produces the cock robin position, but this displacement is usually without a fractured dens. In trauma cases, most commonly, a unilateral combined anterior and posterior subluxation occurs whenthetransverseligamentisdisrupted. The C1 ring may displace anteriorly and reduce the space available for the spinal cord.
• Arteriography may be essential and emergent for any suspected vascular compromise or symptoms consistent with a vascular insult to detect occlusion, thrombosis, or intimal tear. Subtraction angiography may also help evaluate collateral circulation. If any circulatory problems are diagnosed, immediate anticoagulation with heparin prevents further extension of thrombosis, and administration of oxygen maintains cerebral oxygenation.

TREATMENT

Section 7 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Medical therapy

Patients with C1 fractures customarily have some form of trauma; thus, they need to be immediately stabilized at the scene, which requires the customary attention to the ABCs (airway, breathing, and circulation). If the airway is compromised or air exchange is inadequate, intubation without moving the head is crucial (C-spine protection). Careful evaluation and frequent reassessment is needed because the patient may have sustained a concussion with the impact to the head (the common injury that produces the C1 fracture) and, because of a clouded sensorium, may not be able to be fully evaluated or to report neck pain. Patients with a diminished alertness and orientation should carefully undergo imaging studies to exclude underlying pathology.

Surgical therapy

Treatment of the C1 fracture consists of stabilization or immobilization in a satisfactorily reduced position to allow reliable healing. This illustrates the necessity of identifying associated injuries; for example, if a Jefferson fracture is identified but an associated odontoid fracture, transverse ligament fracture, or other problem is present, then halo treatment may be modified or less successful. The transverse ligament is not necessarily expected to heal tightly or reliably, although a bony fracture would be expected to have mechanical integrity restored when healed.

With a C1 fracture, the posterior aspect of the ring becomes disconnected from the anterior aspect, which is stabilized around the odontoid; thus, a posterior fusion of the occiput to C1 would be inadequate to stabilize the spine and, consequently, would extend at a minimum to C2. Customarily, instrumentation attaches a type of contoured rod or plate from the occiput down to C2 to stabilize the area and facilitate healing.

A fractured odontoid fragment cannot be removed from the posterior approach; if a neurologic deficit or threat to the brain stem is present (the alar ligament may have an attached portion of the odontoid migrate superiorly into the foramen magnum to compress the brain stem at the pontomedullary junction), neurosurgical posterior decompression of the foramen magnum could be performed in a halo.

Alternative consideration may be given to a transoral approach or an anterior retropharyngeal approach for the combination of the Jefferson fracture and a fracture of the odontoid. The traditional treatment is a halo vest or cast until the Jefferson fracture is healed. Then, additionally, if the odontoid fracture healing has become delayed or a nonunion is present, this can be treated by a C1-2 arthrodesis, but the procedure must be delayed for the ring of C1 to heal.

For this combined fracture, an anterior open reduction and internal fixation of the odontoid may be performed, with 2 screws placed in an oblique fashion starting at the inferior anterior edge of C2 and directed cephalad to engage the odontoid. With a C1 fracture, this is done in conjunction with a halo vest. An alternative would be a Magerl approach of a posterior open reduction, accompanied by internal fixation of C1-2. For this procedure, 2 screws are placed in an oblique fashion starting at the inferior edge of the C2 lamina, and then they cross the C1-2 facet joint between the vertebral artery, which is lateral, and the spinal cord and brain stem, which are medial.

Preoperative details

The patient must be maintained in protective immobilization—more than a soft collar for adults. Presumably, the patient is in a halo from the point of initial treatment. The reduction of an atlas fracture may be achieved by a ligamentotaxis with mild traction; however, traction is very risky, and such very unstable injuries have to be monitored extremely closely. Associated fractures must be identified expeditiously to direct subsequent treatment. Congenital abnormalities of the arch, such as an agenesis of the posterior ring, must be identified and taken into account in the treatment plan.

Intraoperative details

If the patient is awake and has a halo and vest applied, then the conversation and discussion with the patient during the procedure demonstrates the maintained safety and neurologic status of the patient. Patients who undergo surgical correction, particularly posterior arthrodesis, may be monitored with somatosensory evoked potentials.

Postoperative details

After application of a halo, close follow-up is required with radiographs to demonstrate that the fracture is maintained in a satisfactory position for healing. If surgical stabilization is appropriate, then monitoring the healing of the bone fusion with radiographs is also crucial postoperatively.

Follow-up

Patients in the halo require at least 8 weeks, or likely 12 or more weeks, of immobilization until healing is documented on radiographs. This period is followed by one in which the patient is placed in a collar to protect the neck while he or she is being weaned from the halo and while the neck is gradually being rehabilitated in terms of intrinsic muscle stability and range of motion.

COMPLICATIONS

Section 8 of 12  

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• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Patients with upper cervical instability are at risk of death; this risk is increased if the injury is not identified and recognized. Neurologic damage at this level could make the patient dependent on a ventilator; thus, extreme care is necessary in handling these patients during fracture healing.

Associated injuries to the occipitoatlantoaxial complex must be considered and included in the treatment plan. Devastating neurologic injuries may result from vascular embarrassment resulting from the instability of these injuries.

OUTCOME AND PROGNOSIS

Section 9 of 12  

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• Introduction
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• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Patients with Jefferson fractures are expected to heal and have an excellent prognosis for resumption of activity in the absence of associated injuries. Any surgical stabilization severely restricts the motion of the head, because the occipitoatlantoaxial complex represents over 50% of the motion of the head on the trunk.

FUTURE AND CONTROVERSIES

Section 10 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Disruption of the ring of C1 makes stabilization by a C1-2 fusion in the customary posterior fashion impossible; however, a C1-2 direct fixation with Magerl screws may stabilize the anterior ring to the body of C2. The role of this C1-2 fusion is not yet universally accepted, but with experience, the indications and role will be more clearly defined. A transoral resection of C1 may be preferred to an alternative technique, decompression posteriorly to the foramen magnum, particularly for a migrating odontoid fragment from an associated type 2 Anderson and D'Alonzo odontoid fracture with a Jefferson fracture. The significant amount of rotation of the atlas on the axis would be lost with this fusion, but the fusion would preserve the flexion and extension of the occipital condyle and head on the lateral masses, which would also be lost in an occipital C2 fusion, which is the traditional approach.

With regard to C1-to-C2 fixation, wires have been used for a significant time with excellent results. Gallie (1939) described fusion where wires are passed onto the arch of C1 and into the spinous process of C2. In 1978, Brooks and Jenkins then presented a more stable construct: Rather than placing the bone graft over the posterior elements, grafts are wedged between the posterior arch of C1 and C2, and the wires are passed under both C1 and C2, so they can more effectively stabilize the bone grafts in their respective positions and increase the area for fusion. However, this procedure requires passing the wires more laterally, with careful attention to the vascular structures.

In 2002, Richter et al presented 6 different techniques for biomechanical comparison, preferring transarticular screws but considering isthmic screws with a claw or lateral mass screws and isthmic screws as an alternative with somewhat less immediate stability. A 2003 report by Cornefjord et al on a series of patients with Olerud cervical fixation has also been presented: odontoid fracture occurred in 18 patients, rheumatoid instability in 6, and odontoid nonunion and os odontoideum in 1 patient each, with clinical follow-up (20 patients followed for 6-27 months) suggesting no serious complications and a high frequency of fusion healing.

The posterior arch at C1 has minimal bone for the fusion to heal, and claw techniques to avoid passing sublaminar wires over the brain stem had some early discouraging results, leading to refinements and further investigation. Various techniques will continue to be compared and studied because this is clearly a challenging area.

MULTIMEDIA

Section 11 of 12  

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

Media file 1:  Fracture of the C1 ring may result in lateral displacement and subsequent overhang on the open mouth view in radiographs.
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Media type:  X-RAY

Media file 2:  Computed tomography scanning is often best to visualize C1 ring fractures. Note the anterior disruption, which must be accompanied by another break in the ring.
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Media type:  CT

Media file 3:  Computed tomography sagittal views can be used to evaluate the atlantodens interval or to visualize C1 fractures.
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Media type:  CT

REFERENCES

Section 12 of 12

• Authors and Editors
• Introduction
• Indications
• Relevant Anatomy
• Contraindications
• Workup
• Treatment
• Complications
• Outcome and Prognosis
• Future and Controversies
• Multimedia
• References

• Alker GJ, Oh YS, Leslie EV, et al. Postmortem radiology of head neck injuries in fatal traffic accidents. Radiology. Mar 1975;114(3):611-7. [Medline].
• Anderson LD, D''Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg Am. Dec 1974;56(8):1663-74. [Medline].
• Brooks AL, Jenkins EB. Atlanto-axial arthrodesis by the wedge compression method. J Bone Joint Surg Am. Apr 1978;60(3):279-84. [Medline].
• Bucholz RW, Burkhead WZ. The pathological anatomy of fatal atlanto-occipital dislocations. J Bone Joint Surg Am. Mar 1979;61(2):248-50. [Medline].
• Budin E, Sondheimer F. Lateral spread of the atlas without fracture. Radiology. Dec 1966;87(6):1095-8. [Medline].
• Cornefjord M, Henriques T, Alemany M, et al. Posterior atlanto-axial fusion with the Olerud Cervical Fixation System for odontoid fractures and C1-C2 instability in rheumatoid arthritis. Eur Spine J. Feb 2003;12(1):91-6. [Medline].
• Eismont FJ, Bohlman HH. Posterior atlanto-occipital dislocation with fractures of the atlas and odontoid process. J Bone Joint Surg Am. Apr 1978;60(3):397-9. [Medline].
• Eleraky MA, Theodore N, Adams M, et al. Pediatric cervical spine injuries: report of 102 cases and review of the literature. J Neurosurg. Jan 2000;92(1 Suppl):12-7. [Medline].
• Eubanks JD, Gilmore A, Bess S, et al. Clearing the pediatric cervical spine following injury. J Am Acad Orthop Surg. Sep 2006;14(9):552-64. [Medline].
• Evarts CM. Traumatic occipito-atlantal dislocation. J Bone Joint Surg Am. Dec 1970;52(8):1653-60. [Medline].
• Gabrielsen TO, Maxwell JA. Traumatic atlanto-occipital dislocation; with case report of a patient who survived. Am J Roentgenol Radium Ther Nucl Med. Jul 1966;97(3):624-9. [Medline].
• Gallie WE. Fractures and dislocations of the cervical spine. Am J Surg. 1939;46(3):495-9.
• Garber JN. Abnormalities of the atlas and axis vertebrae--congenital and traumatic. J Bone Joint Surg Am. Dec 1964;46:1782-91. [Medline].
• Grauer JN, Shafi B, Hilibrand AS, et al. Proposal of a modified, treatment-oriented classification of odontoid fractures. Spine J. Mar-Apr 2005;5(2):123-9. [Medline].
• Hamilton MG, Myles ST. Pediatric spinal injury: review of 174 hospital admissions. J Neurosurg. Nov 1992;77(5):700-4. [Medline].
• Hinchey JJ, Bickel WH. Fracture of the atlas: review and presentation of data on eight cases. Ann Surg. Jun 1945;121(6):826-32. [Full Text].
• Jefferson G. Fracture of atlas vertebra. Report of four cases and a review of those previously recorded. Br J Surg. 1920;7:407-22.
• Johnson RM, Hart DL, Simmons EF, et al. Cervical orthoses. A study comparing their effectiveness in restricting cervical motion in normal subjects. J Bone Joint Surg Am. Apr 1977;59(3):332-9. [Medline].
• Levine AM, Edwards CC. Fractures of the atlas. J Bone Joint Surg Am. Jun 1991;73(5):680-91. [Medline].
• Levine AM, Edwards CC. Treatment of injuries in the C1-C2 complex. Orthop Clin North Am. Jan 1986;17(1):31-44. [Medline].
• Lipson SJ. Fractures of the atlas associated with fractures of the odontoid process and transverse ligament ruptures. J Bone Joint Surg Am. Oct 1977;59(7):940-3. [Medline].
• McAfee PC. Jefferson's fracture. In: Frymoyer JW, Weinstein JN, Ducker TB, Kostuik JP, Hadler NM, eds. Adult Spine: Principles and Practice. 2nd ed. Philadelphia, Pa:. Lippincott Williams & Wilkins;1991:1067.
• No authors listed. Isolated fractures of the atlas in adults. Neurosurgery. Mar 2002;50(3 suppl):S120-4. [Medline].
• No authors listed. Management of combination fractures of the atlas and axis in adults. Neurosurgery. Mar 2002;50(3 suppl):S140-7. [Medline].
• North American Spine Society. Spinal cord injury. Available at: http://www.spine.org/fsp/prob_action-injury-cord.cfm. Accessed: November 13, 2006.
• Oda T, Panjabi MM, Crisco JJ 3rd, et al. Experimental study of atlas injuries. II. Relevance to clinical diagnosis and treatment. Spine. Oct 1991;16(10 suppl):S466-73. [Medline].
• Panjabi MM, Oda T, Crisco JJ 3rd, et al. Experimental study of atlas injuries. I. Biomechanical analysis of their mechanisms and fracture patterns. Spine. Oct 1991;16(10 suppl):S460-5. [Medline].
• Patel JC, Tepas JJ, Mollitt DL, et al. Pediatric cervical spine injuries: defining the disease. J Pediatr Surg. Feb 2001;36(2):373-6. [Medline].
• Penning L, Wilmink JT. Rotation of the cervical spine. A CT study in normal subjects. Spine. Oct 1987;12(8):732-8. [Medline].
• Pierce DS, Barr JS Jr. Fractures and dislocations at the base of the skull and upper cervical spine. In: Bailey RW, ed. The Cervical Spine. Philadelphia, Pa:. Lippincott, Williams & Wilkins;1983: 196-206.
• Richards PG. Stable fractures of the atlas and axis in children. J Neurol Neurosurg Psychiatry. Aug 1984;47(8):781-3. [Medline].
• Richter M, Schmidt R, Claes L, et al. Posterior atlantoaxial fixation: biomechanical in vitro comparison of six different techniques. Spine. Aug 15 2002;27(16):1724-32. [Medline].
• Schellhas KP, Latchaw RE, Wendling LR, et al. Vertebrobasilar injuries following cervical manipulation. JAMA. Sep 26 1980;244(13):1450-3. [Medline].
• Sherk HH, Nicholson JT. Fractures of the atlas. J Bone Joint Surg Am. Jul 1970;52(5):1017-24. [Medline].
• Sherk HH, Schut L, Lane JM. Fractures and dislocations of the cervical spine in children. Orthop Clin North Am. Jul 1976;7(3):593-604. [Medline].
• Spence KF Jr, Decker S, Sell KW. Bursting atlantal fracture associated with rupture of the transverse ligament. J Bone Joint Surg Am. Apr 1970;52(3):543-9. [Medline].
• Wetzel SG, Martin JB, Somon T, et al. Painful osteolytic metastasis of the atlas: treatment with percutaneous vertebroplasty. Spine. Nov 15 2002;27(22):E493-5. [Medline].
• White AA, Panjabi MM. Clinical Biomechanics of the Spine. 2nd ed. Philadelphia, Pa:. Lippincott, Williams & Wilkins;1990.
• White AA 3rd, Panjabi MM. The clinical biomechanics of the occipitoatlantoaxial complex. Orthop Clin North Am. Oct 1978;9(4):867-78. [Medline].

Article Last Updated: Dec 1, 2006