You are in: eMedicine Specialties > Orthopedic Surgery > SPINE C2 FracturesArticle Last Updated: Mar 15, 2005AUTHOR AND EDITOR INFORMATIONSection 1 of 10
  Author: Igor Boyarsky, DO, Director of Triage, Assistant Professor, Department of Emergency Medicine, King-Drew Medical Center, University of California at Los Angeles Igor Boyarsky is a member of the following medical societies: American Medical Association, American Medical Student Association/Foundation, American Osteopathic Association, American Society of Addiction Medicine, and Society for Academic Emergency Medicine Coauthor(s): Gary Godorov, MD, Staff Physician, Department of Emergency Medicine, Martin Luther King-Drew Medical Center Editors: James F Kellam, MD, Vice-Chair, Department of Orthopedic Surgery, Director of Orthopedic Trauma and Education, Carolinas Medical Center; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; William O Shaffer, BS, MD, Professor, Vice-Chairman and Residency Program Director, Department of Orthopedic Surgery, University of Kentucky at Lexington; Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital; Mary Ann E Keenan, MD, Professor, Vice Chair for Graduate Medical Education, Department of Orthopedic Surgery, University of Pennsylvania School of Medicine; Chief of Neuro-Orthopedics Program, Department of Orthopedic Surgery, Hospital of the University of Pennsylvania Author and Editor Disclosure Synonyms and related keywords: hangman fracture, odontoid fracture, traumatic spondylolisthesis INTRODUCTIONSection 2 of 10
  Cervical spine (C-spine) injuries are the most feared of all spinal injuries because of the potential for significant deleterious sequelae. Correlation is noted between the level of injury and morbidity/mortality (ie, the higher the level of the C-spine injury - the higher the morbidity and mortality). Craniocervical junction injuries are the deadliest. As many as 10% of unconscious patients who present to the emergency department following a motor vehicle accident (MVA) have C-spine pathology. MVAs and falls are responsible for the bulk of C2 fractures. The clinical manifestations range from asymptomatic to frank paralysis. This article focuses on the uniqueness of and the most common types of traumatic C2 (axis) fractures. Neurologic assessment of C2 fractures (C2 nerve root)
Clinical examination includes the following:
C2 ANATOMYSection 3 of 10
The unique features of C2 anatomy and its articulations make assessment of its pathology challenging. The odontoid process (dens) is a vertical projection that lies just posterior to the anterior arch of C1, has ligamentous attachments to the skull base, and articulates with C1 (atlas). The C1/C2 articulation (ie, atlantoaxial articulation) is made up of 3 joints, including the central atlantoaxial joint and the paired lateral atlantoaxial joints. These joints allow for rotation of C1 on C2. The transverse ligament of the atlas stabilizes the central atlantoaxial joint, and together with the odontoid process, acts as a restraint against horizontal displacement of the atlas. The dentate ligament attaches the apex of the odontoid process to the clivus and the paired alar ligaments, which originate from the transverse ligament and attach to the anterolateral rim of the foramen magnum. These ligaments provide for rotational and translational stability. The lateral atlantoaxial joints articulate at the superior articular facets of C2 and the inferior articular facets of C1. C2 also is composed of inferior facets, pedicles, transverse processes, and a spinal process. COMMON C2 FRACTURESSection 4 of 10
Odontoid fractures Incidence of odontoid fractures approaches 15% of all C-spine fractures. Usually, these fractures are secondary to MVAs or falls. When an odontoid fracture is suspected, it is important to rule out concomitant associated C-spine injuries. For example, C1 anterior ring fractures are not an uncommon finding, and a prevertebral soft-tissue shadow of more than 10 mm on plain films is highly suggestive of such a fracture. Anderson and D'Alonzo classified odontoid fractures based on the anatomic location of the fracture (see Image 4).
The precise mechanism of odontoid fractures is unknown. However, the mechanism most likely includes a combination of flexion, extension, and rotation. In addition to pain and inability to actively move their neck, most patients complain of a sensation of instability, described as a feeling of their head being unstable on the spine. Patients may present by holding their head with their hands to prevent any motion. Clinical signs range from quadriplegia with respiratory center involvement to minimal upper extremity motor and sensory deficits secondary to loss of 1 or more cervical nerve roots. Radiographic findings are based on the type of fracture. C2 lateral mass fractures An isolated C2 lateral mass fracture is extremely rare and usually is found serendipitously when evaluating for other C2 traumatic pathology. If a C2 lateral mass fracture is found, other C-spine pathology must be sought. The mechanism of this fracture is axial compression with concomitant lateral bending. Signs and symptoms of concomitant C-spine pathology tend to dominate the clinical picture. The isolated fracture may present with high neck pain and a normal neurological examination. Radiographic findings include impaction of the C2 component of the atlantoaxial articulation surface, asymmetry of C2 lateral mass height, and lateral tilting of the arch of C1. Atlantooccipital and atlantoaxial dissociation can be seen in Image 2. C2 extension teardrop fractures C2 extension teardrop fractures are avulsion fractures with an intact anterior longitudinal ligament displacing and anteriorly rotating the anteroinferior vertebral body fragment. The avulsed fragment's vertical dimension equals or exceeds its transverse dimension, and focal and minimal prevertebral soft tissue swelling usually is present. This type of fracture tends to occur in elderly patients with osteoporotic bone. As the name implies, this type of fracture is the result of extension forces. C2 extension teardrop fractures tend to be stable and usually are not directly responsible for spinal cord injury. These fractures are extremely rare and differ in many aspects from flexion teardrop fractures that are more common of the lower C-spine. Although lower C-spine teardrop fractures can result from extension forces, usually they result from severe flexion forces. These fractures are unstable and are associated with anterior cord syndrome (quadriplegia; loss of pain, touch, and temperature sensations, but with retention of posterior column functions – proprioception and vibration), secondary to impingement of the cord by the hyperkyphotic vertebral segment or more commonly by retropulsion of C2 into the canal. C2 extension teardrop fractures are associated with traumatic spondylolisthesis of C2. Traumatic spondylolisthesis of C2 (hangman fracture) A great deal of confusion surrounds the exact pathology of this fracture. The modern origin of this confusion seems to be in a paper published by Schneider in 1964, wherein the term hangman's fracture was given to fractures sustained in MVAs and had radiographic similarities to fractures sustained by judicial hangings. In 1964, Garber suggested the term traumatic spondylolisthesis for the more common injury pattern usually seen as a result of falls and MVAs. The injury pattern seen secondary to judicial hangings is a fracture-dislocation of C2. More precisely, it is a bilateral pedicle fracture of C2, along with distraction of C2 from C3 secondary to complete disruption of the disk and ligaments between C2 and C3. The injury pattern seen secondary to MVAs and falls also is a bilateral pedicle fracture but differs from the judicial hanging injury pattern with respect to varying degrees of disk and ligamentous disruption and secondary C2/C3 distraction. The mechanism of a hangman fracture (see Image 3) is a combination of hyperextension nd distraction. The mechanism of the traumatic spondylolisthesis fracture pattern primarily is hyperextension with varying degrees of axial compression and lateral flexion. Without the primary distraction force, there are varying degrees of disk and ligamentous disruption and secondary C2 displacement. Traumatic spondylolisthesis is a common C-spine injury in fatal MVAs, and only occipitoatlantal dissociations occur more often. Up to one third of patients sustaining this injury have additional C-spine pathology, and up to 10% of patients have noncervical spinal pathology. Craniofacial and vertebral artery injuries are not uncommon findings. Interestingly, neurologic sequela from spinal cord pathology is not as common as it might appear to be. This is due to the autodecompression of the spinal canal that takes place secondary to bilateral pedicle fractures. Levine and Edwards recently modified a classification system that was proposed by Effendi. This classification system categorizes these fractures based on the degree of displacement on lateral C-spine radiographs and on mechanical stability. This system is useful in reconstruction of the injury mechanism and in mapping out a treatment.
WORKUPSection 5 of 10
The workup of suspected C2 fractures relies on imaging. Plain film, CT scan, and MRI modalities are all employed. Plain film views should include anteroposterior (AP), lateral, and odontoid views. Additionally, some authors recommend oblique views to better assess the posterior elements. Specific radiographic findings were discussed in the section Common C2 Fractures. Plain films tend to be better than CT at detecting subluxations and dislocations, and CT is usually better at detecting most fractures and also characterizing the extent of the pathology. Most of the fractures that CT misses are those oriented in the axial plane and those involving the odontoid process. Plain film also is better in detecting vertebral body and spinous process fractures. Plain films are routinely used as the study of first choice, and if pathology is found, then CT usually is performed next to help define the extent of the injury. If the plain film studies are not diagnostic and clinical suspicion remains high, then further evaluation using CT is mandatory. Some clinicians advocate the use of 3D CT reconstruction as both a diagnostic aid and also as a surgical template. However, its role has yet to be fully characterized. The role of MRI in spinal trauma is to aid in the characterization of soft tissue injury, neural element injury, and disk injury. This is the study of choice for the evaluation of ligamentous and spinal cord injury and is mandatory in any trauma patient with a neurologic deficit. TREATMENTSection 6 of 10
Odontoid fractures Treatment for type I fractures is hard-collar immobilization for 6-8 weeks, which usually is quite successful. Type II fractures can be managed conservatively or surgically. Treatment options include halo immobilization, internal fixation (odontoid screw fixation), and posterior atlantoaxial arthrodesis. Arthrodesis can be accomplished by C1/C2 transarticular crew fixation, interlaminar clamps, or wiring techniques such as the Gallie or the Brooks method. Management with the halo vest usually is considered if the initial dens displacement is less than 5 mm, the reduction is performed within one week of the injury and is able to be maintained, and the patient is younger than 60 years. During immobilization, alignment is assessed to ensure that reduction is maintained. Displacement of less than 20% is acceptable. The halo vest is in place from 12-16 weeks and the fusion rate is over 90%. Wiring techniques, such as Gallie or Brooks methods, offer a high fusion rate (about 95%); however, the posterior arch needs to be intact and a halo vest must be worn postoperatively. Transarticular screw fixation provides a high fusion rate and the posterior arch need not be intact. Although the posterior surgical fusion techniques provide high fusion success rates, these do so at the expense of cervical rotation. Generally up to 50% of rotation is lost with these techniques. Nonunion, malunion, and pseudarthrosis formation are potential major complications. Factors affecting this are amount and position of displacement, degree of angulation, ability to obtain and hold a reduced fracture, age of the patient, and tolerance to halo immobilization. However, some reports have demonstrated nonunion rates approaching 80% in certain subsets of patients. In a recent paper, Shilpakar and McLaughlin looked at all treatment options and associated rates of complications. Based on a meta-analysis, they concluded that type II fractures are best managed with odontoid screw fixation. Anterior odontoid single screw fixation is noted to preserve normal rotation at C1/C2, provide immediate stability, and obviate the need for postoperative halo immobilization. Furthermore, rates of malunion, nonunion, and pseudarthrosis formation are very low. There are limitations to this approach, namely, the age of the fracture and the patient's body habitus. If the fracture is more than 4 weeks old or if the patient possesses a short neck and barrel-shaped chest, consider an alternative treatment approach such as transarticular screw fixation or Brooks sublaminar fusion. Type III fractures are treated with halo immobilization, odontoid screw fixation, or C1/C2 arthrodesis. Deep, displaced, or angulated fractures are treated with closed reduction and halo thoracic immobilization. Uncomplicated shallow type III fractures are treated with odontoid screw fixation. Nonunion and malunion are potential complications. The vertical type of odontoid process fractures is addressed in the treatment section of Traumatic spondylolisthesis. Lateral mass fractures Treatment ranges from collar immobilization for uncomplicated minimally depressed fractures to cervical traction followed by halo immobilization for more extensive fractures. Complications secondary to posttraumatic degenerative changes may eventually warrant atlantoaxial arthrodesis. Extension teardrop fractures Treatment of these fractures is cervical orthosis, unless more aggressive measures are needed to secure a concomitant unstable fracture. Treatment of type I fractures usually is with a Philadelphia collar or halo. Several treatment options are available for type II fractures, the first being conservative external fixation with halo or tong traction in weighted extension for 1 week. If reduction is acceptable (with less than 4 mm of displacement and less than 10 degrees of angulation), treatment progresses with halo-vest immobilization for 12-16 weeks. If reduction is unacceptable, weighted extension traction resumes for up to 6 weeks, followed by halo treatment for 6 weeks. If adequate results are not achieved after closed reduction and traction, open reduction with anterior cervical plating is the next step. The other surgical treatment option consists of weighted extension traction to accomplish adequate reduction, followed by internal fixation with a C2 transpedicular screw. Conservative and surgical treatments typically yield excellent results. Treatment options for type IIA fractures include both conservative and surgical measures. Conservative treatment consists of closed reduction that is obtained under fluoroscopic guidance via application of compression and extension and followed by halo-vest immobilization. Repeated imaging is used to monitor the healing process with a variant time course. Surgical options include C2 transpedicular screws and anterior cervical plating. Conservative and surgical treatments typically yield very good results. Malunion is a potential complication. For type III fractures, surgery is indicated if the fracture line extends anteriorly to the facet dislocation, at the level of the dislocation, or just posterior to it. Any of these locations make reduction unlikely secondary to instability. In this case, surgical reduction and stabilization is mandated and is accomplished with lateral mass plates, interspinous wiring, or bilateral oblique wiring. Once accomplished, bilateral pedicle fractures can be addressed with C2 transpedicular screws or treated conservatively with traction or a halo/vest. Lateral mass plating of C2 by placing lateral mass screws in C3 in conjunction with C2 transpedicular screws may make the need for postoperative halo immobilization unnecessary. Atypical traumatic spondylolisthesis fractures are managed on a case-by-case basis, weighing the need for more aggressive stabilization against the likelihood of fragment dislodgment and subsequent spinal cord injury. Surgical treatment options for these fractures include C2 transpedicular screw fixation along with odontoid screw fixation. For all types of traumatic spondylolisthesis fractures, nonunion and malunion are the major complications of nonoperative treatment, but fortunately, these are rare occurrences. COMPLICATIONSSection 7 of 10
Complications of C2 fracture treatment are nonunion, malunion, pseudoarthrosis formation, infection, neurovascular injury, acute airway compromise, and hardware failure. The risks of nonunion, malunion, and pseudoarthrosis formation are lessened with surgical treatment. As with any surgical procedure, risk of infection always exists. Osteomyelitis is a rare, but not uncommon, complication. Some authors recommend the use of prophylactic antibiotics for up to 72 hours following surgery and continuation if there is evidence of an infection. Neurovascular injury is a risk associated with any surgical intervention and is a function of both surgical acumen and anatomic variability. Airway compromise is a risk associated with any anterior surgical approach and prolonged endotracheal intubation may be necessary. Common hardware failures include screw bending and breaking, loosening of implants, and hardware failure secondary to osteoporotic bone. OUTCOME AND PROGNOSISSection 8 of 10
Follow-up is critical for any patient sustaining a C2 fracture. In addition to the clinical examination, repeat imaging studies are warranted. Generally, the various treatment modalities used for C2 fractures are quite successful. The only current data available on outcome is for surgical treatment of type II odontoid fractures. A meta-analysis was performed and showed that single screw odontoid fixation using the anterior approach yielded better results than those found with transarticular fusion, multiple screws, or closed reduction with halo vest immobilization. MULTIMEDIASection 9 of 10
REFERENCESSection 10 of 10
Article Last Updated: Mar 15, 2005 | |||||||||||||||||||||||||||||||||
