Fractures of the Odontoid
* Consideration of surgical stabilization and fusion for type II odontoid fractures in patients ≥ 50 years of age is recommended.
* Initial management of nondisplaced type I, type II, and type III odontoid fractures with external cervical immobilization is recommended, recognizing that a decreased rate of union (healing) has been reported with type II odontoid fractures compared with type I or type III odontoid fractures.
* Surgical stabilization and fusion of type II and type III odontoid fractures with dens displacement ≥ 5 mm, comminution of the odontoid fracture, and/or inability to achieve or maintain fracture alignment with external immobilization are recommended.
* If surgical stabilization is elected, either anterior or posterior techniques are recommended.
Traumatic Spondylolisthesis of the Axis (Hangman Fracture)
* External immobilization as the initial management of traumatic spondylolisthesis of the axis is recommended.
* Surgical stabilization and fusion for the treatment of Hangman fractures in cases of severe angulation of C2 on C3, disruption of the C2-3 disk space, and/or inability to achieve or maintain fracture alignment with external immobilization are recommended.
Fractures of the Axis Body (Miscellaneous Fractures)
* External immobilization for the treatment of isolated fractures of the axis body is recommended. Consideration of surgical stabilization and fusion in unusual situations of severe ligamentous disruption and/or inability to achieve or maintain fracture alignment with external immobilization are recommended.
* In the presence of comminuted fracture of the axis body, evaluation for vertebral artery injury is recommended.
The unique anatomy of the axis vertebra results in a variety of fracture patterns in the setting of significant cervical trauma. Fractures of the axis are often associated with other cervical fracture or ligamentous injuries. In 2002, the guidelines author group of the Joint Section on Disorders of the Spine and Peripheral Nerves of the American Association of Neurological Surgeons and the Congress of Neurological Surgeons published a medical evidence-based guideline on this important topic1 and subdivided axis fractures into 3 general subtypes: fractures of the odontoid process, traumatic spondylolisthesis of the axis (Hangman fractures), and miscellaneous nonodontoid non-Hangman fractures of the C2 vertebra. The previous guideline recommended that surgical stabilization of type II odontoid fractures in patients ≥ 50 years of age be considered on the basis of Class II medical evidence. All other recommendations for the treatment of all other isolated fractures of the axis were made at a lower level of medical evidence (Class III) and included both cervical immobilization and surgical fixation with fusion, depending on the fracture type and its radiographic features. It was recommended that type I, II, and III odontoid fractures be managed by immobilization alone. Surgical fixation and fusion were recommended for those cases with a dens displacement of ≥ 5 mm, comminution of the odontoid fracture (type IIA fractures), and/or the inability to maintain fracture alignment. It was recommended that traumatic spondylolisthesis of the axis be managed initially with external immobilization. However, consideration of surgical stabilization and fusion for Hangman fractures was recommended in cases of severe angulation of C2 on C3 (Francis grade II and IV, Effendi type II), disruption of the C2-3 disk space (Francis grade V, Effendi type III), or the inability to maintain alignment with external immobilization. Finally, it was recommended that fractures involving the axis body be treated with cervical immobilization. The purpose of this review is to update the medical evidence on the treatment of isolated axis fractures since the 2002 guidelines publication.1
A National Library of Medicine (PubMed) computerized literature search from 1966 to 2011 was undertaken using Medical Subject Headings in combination with “spinal cord injury”: “axis,” “vertebrae,” “fracture,” and “human.” A total of 1181 articles were identified. Those articles focusing on the clinical management of acute traumatic axis fractures were selected for review. The bibliographies of these articles were scanned for additional references to confirm completeness of the literature review. Relevant articles addressing the mechanism of injury or the biomechanics and radiology of the C2 vertebra were considered for inclusion in the scientific foundation of this document.
Forty-six articles not previously included in the original guidelines document were identified, reviewed, and classified using established methodology. Thirty-one articles described the management of odontoid fractures; 10 articles were focused on traumatic spondylolisthesis of the axis; and 5 articles described the treatment of patients with miscellaneous axis fractures and are summarized in Evidentiary Table format.
Classification of Odontoid Fractures
The classification of odontoid fractures into 3 types, as described by Anderson and D’Alonzo2 in 1974, remains an accepted classification scheme for odontoid fracture injuries. The authors defined 3 odontoid fracture types based on their series of 49 patients. Type I fractures were described as oblique fractures through the upper portion of the odontoid process. Type II fractures were described as fractures across the base of the odontoid process near the junction with the axis body. Type III fractures were fractures that include the odontoid and extend into the body of the axis. This historic series includes 2 type I fractures (4%), 32 type II fractures (65%), and 15 type III fractures (31%). Hadley et al3 modified this classification scheme in 1988, defining the type IIA odontoid fracture as a comminuted fracture of the base of the odontoid with associated free fracture fragments. This unique fracture was associated with severe instability in their series and represented 3 of the 62 type II odontoid fractures they treated. Further odontoid fracture classification modification was proposed by Grauer et al,4 who described 3 subtypes of type II fractures. Type IIA was defined as a minimally or nondisplaced fracture with no comminution treated with external immobilization. Type IIB was defined as a displaced odontoid fracture that extends from anterior-superior to posterior-inferior, or a transverse fracture, amenable to anterior screw fixation if reducible, assuming adequate bone quality. Type IIC was defined as a fracture extending from anterior-inferior to posterior-superior or a fracture with significant comminution likely to be considered for posterior internal fixation and fusion. These modifications were introduced to specifically address the issue that the original Anderson-D’Alonzo scheme did not take into account the direction of the fracture across the dens, the presence of comminuted fragments, or the degree of displacement or angulation of the fractured odontoid process. In addition, the authors noted the difficulty in differentiating a low type II fracture from a high type III fracture. They applied their revised scheme to a series of 52 patients with odontoid fractures. Seven raters were asked to characterize the odontoid fracture injuries. There was agreement in 70% of the cases by at least 5 of 7 raters. The overall κ value for the modified system was 0.48, indicating moderate to good agreement. Other than this single study, none of these classification schemes (Table 1) have been subjected to rigorous validity and reliability evaluation.
Numerous therapeutic strategies for odontoid fracture management have been described on the basis of a variety of factors, including the fracture type, degree of dens displacement, angulation of the dens with respect to the body of C2, interval between the fracture and treatment, and patient age. The medical evidence supporting the nonoperative management of odontoid fractures with external immobilization, including traction, a cervical collar, or the halo orthosis (including custom devices such as the suboccipital mandibular device and Minerva devices), and the surgical management of these fracture injuries, including posterior cervical fusion with or without supplemental screw fixation or anterior odontoid screw fixation, is the subject of this updated review.
In 1985, the Cervical Spine Research Society published a multicenter review addressing the management of odontoid fractures. Their report included 18 patients with type II odontoid fractures and 3 patients with type III odontoid fractures who received no treatment. None of these patients achieved bony healing or fracture union. The authors concluded that no treatment was not a good option for patients with odontoid fractures.5
Evidence-based reviews by Traynelis6 in 1997 and Julien et al7 in 2000 include evidentiary tables that contain Class III medical evidence addressing the use of traction and subsequent immobilization in a cervical collar for patients with odontoid fractures. The combined radiographic union rates from these reports were as follows: type I, 100% (3 of 3); type II, 43% (42 of 97); and type III, 87% (55 of 63).
As described in the previous guideline publication, the treatment of the infrequent type I odontoid fracture with cervical collar immobilization has been reported to be successful in nearly 100% of cases (Class III medical evidence).2,5,8 No new data of higher quality was identified in this review. Previous Class III medical evidence reports describing the outcome of type II fractures treated with a cervical collar alone resulted in union rates ranging from 53% to 57%.9,10 The management of type III odontoid fractures with cervical collars results in union rates ranging from 50% to 65%, also based on Class III medical evidence.5,10
In the largest reported series of axis fractures published in 1997, Greene et al11 described the management of 199 patients with odontoid fractures: type I, n = 2; type II, n = 116; type IIA, n = 4; and type III, n = 77. Union rates for those treated with a halo orthosis were reported to be the following: for type I, 100% (2 of 2); for type II, 72% (68 of 95); and for type III, 99% (68 of 69). Analysis of the type II fractures with nonunion indicated that a dens displacement of ≥ 6 mm was associated with an increased rate of nonunion regardless of patient age, direction of displacement, or neurological deficit. The negative impact of dens displacement ranging from 2 to 6 mm on successful healing/union was confirmed in other reports.5,12-14
The evidenced-based review by Julien et al7 included a total of 269 patients with odontoid fractures treated with rigid external fixation (halo orthosis or Minerva vest) for 8 to 12 weeks. Reported union rates were as follows: for type, I 100% (3 of 3); for type II, 65% (110 of 168); and for type III, 84% (67 of 80). The Class III medical evidence provided in these reports was the foundation for the option level/Level III recommendations for treatment of odontoid fractures published in the previous guideline.
Shears and Armitstead15 in 2008 published a Cochrane Review of odontoid fracture management and concluded that no randomized medical evidence existed on this topic.
In 2007, Platzer and colleagues16 reported their series of 90 patients with type II odontoid fractures. The authors prospectively studied the success of halo immobilization with union as the outcome of interest. The mean patient age in their series was 69 years. The reported union rate was 84% (76 of 90). Eighty-three percent of these patients (75 of 90) returned to their preinjury status. The authors identified the following risk factors for failure of halo immobilization (P < .05): older patients (cases, 77.2 years vs controls, 60.8 years; P < .05) and displaced fractures > 2 mm (cases, 11 of 14 [79%] vs controls, 16 of 76 [21%]). Two other factors had a significant effect on the multivariate regression analysis they performed: secondary loss of reduction and delay of treatment (P < .05). If 2 of these covariate risk factors were present, there was a 57% risk of nonunion. The likelihood of nonunion increased to 70% with 3 covariate risk factors and was 87% when all 4 risk factors were present. The authors concluded that halo immobilization provided satisfactory outcome with an 84% union rate. This publication supports the previous case-control study published by Lennarson et al17 in which patient age was identified as a risk factor for nonunion, along with the degree of dens displacement, secondary loss of reduction, and delay of treatment. Although the authors described their analysis as a case-control study, with respect to treatment, it is a prospective cohort study. Because all of the patients were treated the same, there is no comparison group. Their study offers Class III medical evidence on this topic.
Kim et al18 present a prospective cohort study of 20 patients with type II odontoid fractures to evaluate radiographic indicators for predicting failure of treatment with halo immobilization. Of 14 patients in a halo group, 4 patients developed nonunion. All 4 patients had a > 5° change of angulation in the dens fracture between supine and upright films at the 2-week time point. None of the patients in the successful union group demonstrated this radiographic finding.
In 2005, Kontautas et al19 reported their prospective nonrandomized cohort study of 37 patients with type II odontoid fractures treated initially with traction to determine reducibility. Two groups were identified: group 1with dens displacement ≤ 5 mm and group 2 with dens displacement > 5 mm. The groups were equivalent by age, sex, neurological condition, and associated spinal fractures (P > .05). Eleven group 1 injuries (64%) and 13 Group 2 fractures were able to be reduced and treated in a halo device. The nonunion rate at 8 weeks for group 1 injuries was 0%. Fracture injuries had a 16.7% nonunion rate. Patients with fractures that could not be reduced and those who failed halo treatment were treated with posterior internal fixation and fusion. The authors concluded that when closed reduction of an odontoid fracture can be achieved, external immobilization with a halo-vest device will likely be effective.
Nourbakhsh et al20 published a meta-analysis using a random-effects model to assess the effectiveness of nonoperative management of type II odontoid fractures. The authors identified a union rate > 80% for all patients < 55 years of age regardless of the mode of treatment. External immobilization (halo vest or collar) was equally effective with anterior displacement of the dens fracture and younger patients (< 55 years of age).
Müller et al21 in 2003 reported a retrospective analysis of 26 “stable” type II and III fracture patients managed with collar immobilization. A stable fracture met the following criteria: fracture gap of < 2 mm, displacement of < 5 mm, and angulation of < 11°. Reported union fusion rates were 73.7% for type II fractures and 85.7% for type III fractures. In 4 patients (15%), a fibrous union was documented. Three of these patients were > 65 years of age. No correlation between clinical outcome and the radiological finding of a fibrous union was identified. Patients with a stable fibrous union were as pleased with their outcome as those patients with documented bony fusion. The authors concluded that stable type II and III fractures of the odontoid can be treated successfully with collar immobilization.
In 2010, Butler et al22 reported their series of 66 patients with type II odontoid fractures treated with halo immobilization. The nonunion rate was 21% in patients > 65 years of age (compared with 2% for patients < 65 years of age). Age was associated with poorer functional outcomes. Similarly, Komadina et al23 described a high rate of union for type II and III odontoid fractures managed in a halo immobilization device (86%). Sixty-five percent of their patients had complete symptom resolution at the 1-year follow-up.
Posterior Cervical Fixation
The previous guideline publication summarized the outcome of 177 patients with odontoid fractures treated with posterior cervical fixation and fusion. Fusion success after operative treatment was as follows: type I, 100% (1 of 1); type II, 87% (128 of 147); and type III, 100% (29 of 29). Of note, Maiman and Larson24 reported a union rate at the fracture site of only 35% but a fusion rate of 100% at the posterior operative site. These patients were treated with an instrumented (wire or cable) posterior C1-2 arthrodesis followed by immobilization in a rigid orthosis. At the time of the previous guideline publication, transarticular screw fixation and fusion of C1-2 had been described,25 particularly in patients with fracture nonunion after initial management, but the experience was limited.
Anterior Cervical Fixation
Screw fixation of odontoid fractures from an anterior approach, although technically challenging, has the potential to maintain rotational motion at the atlantoaxial joint, which is lost with posterior C1-2 fusion techniques. Anterior odontoid screw fixation is best suited for fractures that are either horizontal or oblique and posterior with an intact transverse atlantal ligament.26-29 The previous guideline identified Class III medical evidence addressing the role of anterior odontoid screw fixation. Julien et al7 described fusion rates of 89% (112 of 126) for type II fractures and 100% (20 of 20) for type III fractures. Subach et al30 reported 1 failure resulting from inadequate reduction in their series of 26 type II fractures treated with anterior odontoid fixation (fusion rate, 96%). The success of anterior odontoid fixation has been reported to be similar with 1 vs 2 screws (81% vs 85%)31 and greater when it is performed within 6 months of injury compared with 18 months after injury (88% vs 25%).32
Smith et al33 examined a 20-year period to identify trends in the role of surgery for type II odontoid fractures. They found that the rate of surgical intervention for these injuries increased during the study period. A thorough report on the role of surgery for odontoid fractures was published recently by Nourbakhsh et al.20 Their meta-analysis offers Class III medical evidence on this issue. The authors concluded that operative treatment of acute type II fractures (posterior C1-2 fixation or anterior screw fixation) increases the union/fusion success rate compared with external immobilization and is recommended for older patients, patients with posterior displacement of the dens fracture, and in cases with dens displacement > 4 to 6 mm.
A large number of case series without comparison groups (Class III medical evidence) have been published and support the safety and efficacy of anterior odontoid screw fixation in the treatment of type II and III odontoid fractures. Moon et al34 treated 32 patients with type II or III odontoid fractures with anterior odontoid screw fixation followed by halo vest immobilization and reported a 100% fusion rate at 9 weeks. Fountas et al35 in 2005 reported their results with anterior odontoid screw fixation in 31 patients with type II and “shallow” type III odontoid fractures. They identified an 87% fusion rate at long-term follow-up (mean, 58.4 months). Lee et al36 described 48 patients with type II and III odontoid fractures treated with single anterior odontoid screw fixation. They reported a fusion rate of 96% and a failure rate of 10% (1 nonunion and 1 malposition). Bhanot et al37 reviewed their experience with 17 type II odontoid fractures managed with ventral screw fixation. They reported fusion in 94% of patients (16 of 17) with 1 nonunion and 1 case of screw back-out. Chi et al38 described 10 patients with type II and III odontoid fractures managed with a percutaneous anterior odontoid screw technique. They described fusion success in 9 of 10 patients. Song et al39 described 16 patients with type II and III odontoid fractures treated with single anterior odontoid screw fixation. They found a 94% fusion rate. One patient required a subsequent posterior procedure. Cervical spine range of motion after treatment was reported as full in 12 patients and limited in 4 patients.
Odontoid Fracture Management in the Elderly Patient
The management of odontoid fractures in the elderly is controversial. The previous guideline publication identified 1 Class II medical evidence article favoring surgical fixation of type II odontoid fractures in patients > 50 years of age. Multiple Class III medical evidence articles offer conflicting evidence on this issue, although the majority of the case series previously reviewed support a role for surgery in elderly patients with type II odontoid fractures.
The case-control study by Lennarson et al17 provides Class II medical evidence on the topic. The authors examined 33 patients with isolated type II odontoid fractures treated with halo vest immobilization. Patients were divided by age and outcome and by union or nonunion of their odontoid fracture. Patients ≥ 50 years of age had a risk of nonunion 21 times greater than patients < 50 years of age when treated with halo immobilization. Medical conditions, sex of the patient, degree of fracture displacement, direction of fracture displacement, length of hospital stay, and length of follow-up were not found to have a significant effect on outcome.
The ability of elderly patients to tolerate halo fixation immobilization has been questioned.40 Mortality rates as high as 26% with the use of the halo device have been reported.41 Reported union rates for odontoid fractures in elderly patients treated with halo immobilization vary between 20% and 100% in the literature.2,41,42 Fusion rates reported for elderly patients treated with surgery are generally higher.2,43,44 The majority of published papers on this topic favor consideration of surgery in the elderly patient with an odontoid fracture.25,45-47 Multiple Class III medical evidence articles and the single Class II medical evidence citation formed the basis for the previous guideline recommendations on the management of odontoid fractures. The current review identified 12 citations on the management of elderly patients with odontoid fractures published since 2002. All provide Class III medical evidence.
Börm et al48 reported their study of the effect of age on outcome in 27 patients with type II odontoid fractures treated with anterior odontoid screw fixation. The patients were evaluated in 2 groups. Group 1 contained patients ≥ 70 years of age, and group 2 contained patients < 70 years of age. The groups were equivalent in terms of demographics. There was no significant difference between the 2 groups with respect to fusion success rate (73% vs 75%), the need for subsequent posterior operative procedures (13% vs 17%), or the incidence of complications (20% vs 8%). This article provides Class III medical evidence that age alone does not have a negative impact on outcome after anterior odontoid screw fixation.
Dailey et al49 retrospectively reviewed 57 type II odontoid patients > 70 years of age whom they treated with anterior odontoid screw fixation. Postoperative stability was reported in 81% of the patients. In patients treated with 2 screws, stability was 96% compared with 56% for 1-screw fixation. They reported a 25% incidence of significant dysphagia and a 19% rate of aspiration pneumonia in their series.
Platzer et al50 in 2007 published their series of patients with type II odontoid fractures (n = 110) managed with anterior screw fixation. They examined the effect of age on nonunion. The overall fusion rate was 93%. They identified an increased rate of nonunion in older patients (12% vs 4%; P < 0.05). The authors concluded that anterior screw fixation was a safe and effective option for the treatment of type II odontoid fractures in patients of all ages.
Smith et al51 published a retrospective cohort analysis of older patients with type II odontoid fractures (≥ 80 years of age) and compared operative (n = 32) and nonoperative (n = 20) treatment strategies. The length of acute hospital stay was longer in the operative treatment patients (mean, 22.8 vs 11.2 days; P < .05). Significant complications were greater in the operative group compared with the nonoperative group (62% vs 35%; P < .05). The mortality rate was similar in the 2 groups (12.5% vs 15%; P > .05) The authors concluded that type II odontoid fractures in the octogenarian population are associated with significant morbidity and mortality regardless of management. They found that nonoperative management was associated with fewer complications and outcomes similar to those from operative management. This retrospective comparative cohort study offers Class III medical evidence on this topic.
White et al52 published a systematic review of the literature from 1990 through 2010 on the role of surgery for odontoid fractures in the elderly. Fourteen articles met their criteria for analysis. They identified a postoperative mortality rate of 10.1% (in-hospital, 6.2%; after discharge, 8.8%). There was no difference in postoperative mortality on the basis of operative approach, anterior vs posterior. The incidence of postoperative complications in this patient group was airway compromise (17%), pneumonia (9.9%), respiratory failure (7.7%), cardiac failure (6.8%), deep vein thrombosis (3.2%), stroke (3.2%), liver failure (6.7%), and severe infection (3.2%).
Koech et al53 evaluated the effectiveness of nonoperative management of type II odontoid fractures in 42 elderly patients treated with either collar (n = 10) or halo (n = 32) immobilization. They found bony fusion rates of 50% and 37.5%, respectively. They described radiographic stability rates of 90% and 100%, respectively. They found no difference in clinical outcome between bony fusion, fibrous union, and radiographic stability. The authors suggested that fibrous union with radiographic stability may be a suitable outcome in elderly patients.
Majercik et al54 compared patient age and outcome with treatment in a halo immobilization device (not specifically odontoid fracture patients) and found a mortality rate of 21% in patients ≥ 66 years of age compared with 5% in patients < 66 years of age (P < .05). These authors strongly recommended against halo vest immobilization in the treatment of cervical fracture injuries in elderly patients if other treatment alternatives were available.
Similarly, Tashjian et al55 reported the morbidity and mortality of halo immobilization compared with collar and/or operative treatment in a cohort of 78 patients with type II, type III, and combination atlas-axis fractures in patients with a mean age of 81 years. All patients were > 65 years of age. There were 24 deaths during the initial hospitalization (31%). Of those treated in a halo device, 42% died. Major complications were twice as likely with a halo device, 66% vs 36% (P = .003). The authors concluded that odontoid fractures are associated with significant morbidity and mortality in the elderly. Both appear to increase significantly when treated in a halo immobilization device.
In 2010, Fagin et al56 published a retrospective review of 108 patients with odontoid fractures whom they managed. Sixty-nine patients were managed nonoperatively; 17 were treated with an immediate operation; and 23 were treated with a delayed operation. The mean age of the nonoperative group was older, 82.4 years, compared with 77.4 and 76.4 years, respectively (P = .006). The mortality rate was not significantly different between the 3 groups (17.6%, 11.7%, and 8.7%, respectively; P > .05). The need for tracheostomy or gastrostomy and the development of urinary tract infection or pneumonia were equivalent in all groups. The incidence of deep vein thrombosis was lower in the nonoperative group compared with the early surgery group (3% compared to 18%; P = .02). The length of stay was less for nonoperative patients compared with operated patients (8.5 compared to 13.9 days; P < .001). The authors recommended that nonoperative treatment be strongly considered for elderly patients with odontoid fractures.
In 2009, Omeis et al57 described 24 elderly patients with type II odontoid fractures treated surgically. They found a 7% incidence of central cord syndrome at presentation. Perioperative complications were identified in 10.3% of patients, including 1 perioperative death caused by a myocardial infarction. Sixteen patients underwent anterior odontoid screw fixation, and 13 underwent posterior fixation and fusion. Ultimately, 86.2% of patients treated surgically returned to their previous level of activity. The authors concluded that the elderly patient with a type II odontoid fracture can be treated with surgical fixation and fusion with acceptable morbidity and a relatively high expectation of returning to their preinjury status.
Frangen et al58 published a retrospective review of elderly patients (median age, 85.5 years) with type II odontoid fractures treated with posterior C1-2 fusion. Their 2010 publication described a 22% perioperative mortality rate. Survivors in their series had a 95% rate of fusion with minimal operative complications. The authors concluded that compared with historical control subjects described in the literature, their fusion rate was high. They concluded that posterior surgery is recommended for the treatment of type II odontoid fractures in the elderly, but they recognized the relatively high mortality rate in this age group.
Traumatic Spondylolisthesis of the Axis (Hangman Fracture)
Classification of Hangman Fractures
Historically, the classification schemes for traumatic spondylolisthesis of the axis proposed by Effendi et al59 and Francis et al60 (with modification by Levine and Edwards61) have been the most widely used. The Francis classification60 recognizes 5 injury grades of increasing severity based on displacement and angulation of C2 on C3:
* Grade I: fractures with 0- to 3.5-mm displacement and/or C2-3 angulation up to 11°
* Grade II: fractures with displacement < 3.5 mm and angulation > 11°
* Grade III: fractures with displacement > 3.5 mm but less than half of C3 vertebral width < 0.5 and angulation < 11°
* Grade IV: fractures with displacement > 3.5 mm but less than half of C3 vertebral width with > 11° angulation
* Grade V: fractures with complete C2-3 disk disruption.
The classification scheme proposed by Effendi et al59 defines 3 types of fractures of the ring of the axis based on the mechanism of injury:
* Type I: isolated hairline fracture of the ring of the axis with minimal displacement of the body of C2 associated with axial loading and hyperextension
* Type II: fractures of the ring of the axis with displacement of the anterior fragment with disruption of the disk space below the axis associated with hyperextension and rebound flexion
* Type III: fractures of the ring of the axis with displacement of the body of the axis in a flexed forward position (angulation), in conjunction with C2-3 facet dislocation associated with primary flexion and rebound extension.
The incidence of type I, II, and III fracture injuries in the Effendi et al59 original series of 131 patients was 65%, 28%, and 7%, respectively.
The modification of the Effendi classification scheme proposed by Levine and Edwards61 added flexion-distraction as a mechanism of injury (type IIA), with 4 injury types:
* Type I: nondisplaced fractures and all fractures with < 3-mm displacement of C2 on C3 associated with hyperextension and axial loading.
* Type II: fractures with significant displacement (> 3 mm) and angulation > 11° defined as displacement of the anterior fragment with disruption of the C2-3 disk space associated with hyperextension and secondary flexion-compression.
* Type IIA: fractures with a minimum degree of C2-3 displacement but severe angulation associated with flexion-distraction
* Type III: fractures with unilateral or bilateral C2-3 facet dislocation in addition to fracture of the posterior elements associated with flexion-compression.
Greene et al11 applied the Francis and Effendi classification schemes to 74 patients with Hangman fractures. They noted a strong correlation between Francis grade I and Effendi type I injuries and between Francis grade IV and Effendi type III injuries. The most common fracture types in their series were Effendi type I (72%) and Francis grade I (65%). Burke and Harris62 applied the Effendi classification scheme to their series of 65 patients with Hangman fractures; 11% of the fracture injuries in their series were not accurately described by the Effendi scheme.
The initial management of Hangman fractures has typically been nonsurgical, and high success rates have been reported. Early surgical stabilization and fusion of Hangman fractures have been reserved for situations of severe C2-C3 instability. The series described by Effendi et al,59 Francis et al,60 and Greene et al11 reported that the majority of patients with Hangman fractures were effectively treated with external immobilization. These authors recommended that surgical internal fixation and fusion be reserved for Effendi type III fractures and for nonunion of other Hangman fractures after 3 months of halo immobilization.
In the Levine and Edwards61 series of 52 patients with Hangman fractures, all isolated Effendi type I, II, and IIa injuries were successfully managed nonoperatively (n = 47 combined). Three of the 5 type III injury patients (60%) required surgical stabilization for failure to obtain or to maintain fracture reduction with a halo orthosis.
The Francis et al60 series of 123 patients with Hangman fractures, from which their classification scheme was developed, reported that nonoperative management (traction followed by conversion to halo fixation) was successful in 95% of patients (116 of 123). Three of 9 grade II injury patients (33%) and 2 of 7 grade V injury patients (28%) developed nonunion despite halo management and required subsequent surgical treatment. Greene et al11 successfully treated 65 of 74 patients (87%) with Hangman fractures nonoperatively with external immobilization for a median of 12 weeks. Of patients with either Effendi type II or III injuries, 7 (33%) required early surgical treatment because of failure of external immobilization. The authors concurred with Effendi et al and Francis et al that conservative management (external immobilization) should be the initial treatment in virtually every patient with a Hangman fracture. They concluded that early surgical management of Hangman fractures should be reserved for unstable injuries ineffectively immobilized in a halo device. Reports of smaller case series have described 100% successful fracture union with halo immobilization (42 patients)63 or cervical collar immobilization alone (39 and 8 patients64,65a) regardless of C2-3 displacement or angulation. Class III medical evidence describing the nonoperative management for Hangman fractures is found in Table 3.
The current updated literature search on the management of Hangman fractures identified additional Class III medical evidence in support of initial nonoperative management for these injuries. To be fair, halo immobilization does not always achieve or maintain fracture reduction, as evidenced by the occasional need for surgical fixation in the larger series reported previously.11,59,60 Halo immobilization is associated with a number of known complications, including but not limited to pin loosening, infection, cranial fracture, pressure sores, poor patient compliance, pulmonary issues, pneumonia, and restricted patient mobility.54 Although treatment over and above fracture immobilization may not be necessary, there may be significant management advantages in avoiding the potential complications associated with halo vest use by performing early surgery to stabilize and fuse the C2-C3 vertebral segments.
In their review of axis fractures, Suchomel and Hradil65b presented their argument in favor of early surgical fixation: “A fracture-dislocation of the C3/4 level in an otherwise healthy person would be treated by anterior surgery and fusion today. It becomes very hard to find a reasonable argument against the use of the same principle for C2/3 intervertebral space.”
Li et al65a in 2006 performed a systematic review to address the issue of the operative vs the nonoperative management of Hangman fractures. The authors indicated that the classification scheme by Effendi et al as modified by Levine and Edwards was preferred. Thirty-one of the 32 articles they included in their review (97%) advocated nonsurgical management for Hangman fractures. The authors summarized the literature and made the following recommendations for the treatment of Hangman fractures:
* Levine-Edwards type I and II injuries: nonrigid external fixation was sufficient.
* Effendi type I and II and Levine-Edwards type II fractures: traction followed by external immobilization.
* Levine-Edwards type IIa and III and Effendi type III fractures (significant dislocation): rigid immobilization; consider surgical fixation and fusion.
Watanabe et al66 reported 9 patients with Hangman fractures treated with halo immobilization. They observed that those patients with angulation and C2-3 translation caused by fracture of the inferior C2 facet joint had a worse outcome and should be considered for surgical fixation and fusion rather than halo immobilization.
In 2001, Moon et al67 described a series of 42 patients with Hangman fractures. Patients without displacement or angulation were considered stable (n = 20) and were treated with traction followed by a cervical orthosis with 100% fusion success. Patients with C2-3 angulation or displacement with ligamentous disruption were considered unstable and were treated with anterior C2-3 interbody fusion. They described a 100% fusion rate and reported no complications.
Vaccaro et al68 described their experience with early halo immobilization in a series of 31 patients with Hangman fractures (type II, n = 27; type IIA, n = 4). All the type IIA patients achieved bony union and 21 of 27 of the patients with type II injuries (78%) achieved successful union. Six patients with type II injuries (22%) failed initial attempts at closed reduction/immobilization and had to be replaced in traction, which was followed by surgical fixation and fusion. All 6 patients (100%) had an initial fracture angulation of 12° or greater.
A number of investigators have advocated early surgical intervention for patients with more severe Hangman fracture injuries, particularly those patients with significant displacement and angulation at the C2-C3 level. The reported advantages of surgical treatment include improved fracture alignment, reduction in hospitalization and treatment times, faster patient mobilization, and potentially an improved quality of life. Surgical options for unstable Hangman fracture injuries, particularly those that fail to heal despite external immobilization, include anterior C2-3 interbody fusion,59 dorsal C1-C3 fusion procedures,69 direct pars fixation,70 or combinations of these approaches. Class III medical evidence addressing surgery for Hangman fractures is found in Table 3.
Anterior surgical approaches to C2-C3 have the advantage of being safe and familiar to surgeons. Xu et al71 retrospectively reviewed their series of 28 patients with Effendi type II and III Hangman fractures treated with C2-3 anterior discectomy and fusion. Fusion was obtained in 100% of cases, and complete recovery was reported. Ying et al72 reported 30 patients with Effendi type II and III Hangman fractures treated with anterior cervical discectomy and fusion. They described 100% fusion success at 6 months with 1 transient complication (dysphagia).
Posterior surgical approaches have the advantage of allowing direct access to the C2-3 facets for reduction (Effendi type III). The additional muscle dissection required with this approach may be a disadvantage for patients with less severe Hangman injuries. A posterior approach for reduction and stabilization coupled with anterior C2-3 fusion has been reported for severe C2-3 instability. Direct pars fixation has been described as an alternative for Hangman fractures with limited disk and ligamentous injury but may be the most technically challenging procedure. As with any posterior C2 screw fixation technique, there is concern for vertebral artery injury. ElMiligui et al73 described their operative experience with 15 type II Hangman fractures treated with transpedicular screw fixation. They reported a fusion rate of 100% with minimal complications and preservation of postoperative range of motion. In 2009, Dalbayrak et al74 described 4 patients with Levine-Edwards type II Hangman fractures treated with C2 pars fixation. All 4 patients had successful union. Boullosa et al75 reported 10 Hangman fracture patients successfully treated with transpedicular C2 fixation in whom external immobilization had failed or a halo device was contraindicated. They described a 100% fusion success rate. Ninety percent of their patients experienced complete resolution of symptoms.
Fractures of the Axis Body
The treatment of miscellaneous fractures of the axis body remains challenging because of their diversity and relative infrequency. The majority of clinical reports cited in the literature describe successful fracture union with nonoperative techniques. The most comprehensive attempt at classifying these fractures remains the report of Benzel et al.76 They characterized C2 body fractures into 3 anatomical subtypes: type I, coronal; type II, sagittal; and type III, transverse. The Greene et al11 series included 61 patients with miscellaneous axis fractures. Ninety-nine percent were treated successfully with nonoperative techniques. Only 1 patient with a miscellaneous axis fracture required surgical intervention for delayed nonunion. Class III medical evidence studies on the treatment of miscellaneous fractures of the axis described in the previous guideline on this subject are compiled in Table 4. Of the 119 patients included in these reports, 117 were successfully treated nonoperatively (99%). The present updated review of this topic identified 5 additional citations. All provide Class III medical evidence and are summarized in Table 4.
In 2010, Ding et al77 published a retrospective review of 102 patients with axis fractures of all types and found that comminuted fractures of any type with fragments of bone within the foramen transversarium were associated with an increased risk of vertebral artery injury. Many miscellaneous axis fractures involve the transverse foramen; therefore, a high level of suspicion for potential vertebral artery injury should be maintained when these patients are evaluated. Aydin and Cokluk78 described an axis pars interarticularis fracture that they successfully treated with a cervical collar. German et al79 described their series of 21 patients with vertical C2 body fractures. Sixteen were coronally oriented type I vertical C2 body fractures, and 5 were sagitally oriented type II C2 body fractures. Three patients died of associated injuries. All 18 surviving patients (100%) were successfully treated nonoperatively. Korres et al80 reported 2 separate observations after review of their database of 674 cervical fractures. The first80 described the incidence of horizontal (Chance-type) fractures of the atlas, identified in 2 of 674 injuries that they managed (0.05%). Both were treated nonsurgically with success at the long-term follow-up. The second observation81 described the occurrence of multiple fractures of the atlas, an injury that occurred in 9 of their 674 patients (1%). The most common multiple fracture patterns were a teardrop fracture of the axis body associated with a traumatic spondylolisthesis or the combination of a traumatic spondylolisthesis of the axis with an odontoid fracture. The authors recommended computed tomography as the imaging modality of choice for patients with C2 fractures.
A summary of the recommendations for the acute management of axis fractures is provided in Table 1 and the data supporting the recommendations in this section are provided in Table 2.
Fractures of the Odontoid
There is no Class I medical evidence on the management of patients with acute traumatic odontoid fractures. Class II medical evidence exists indicating that the risk of nonunion of a type II odontoid fracture in patients ≥ 50 years of age is 21 times greater than the incidence of nonunion for younger patients with a similar type II odontoid fracture. Therefore, consideration of surgical stabilization and fusion for type II odontoid fractures in patients ≥ 50 years of age is recommended. Type I, II, and III odontoid fractures are often effectively managed with external cervical immobilization, with the understanding that the failure of external immobilization is significantly higher for type II odontoid fractures. Treatment of type II odontoid fractures with a cervical collar alone or traction followed by cervical collar immobilization may be undertaken but is associated with lower fracture union rates. Class III medical evidence indicates that factors associated with nonunion of type II fractures include age, fracture displacement, secondary loss of reduction, and delays in treatment. Similarly, Class III medical evidence suggests that a change in angulation of the type II odontoid fracture of ≥ 5° on lateral radiography taken at 2 weeks after immobilization in a halo device is associated with failure of fusion. Closed reduction of displaced type II odontoid fractures is associated with successful treatment with halo immobilization. Type II and III odontoid fractures should be considered for surgical fixation in patients with dens displacement of ≥ 5 mm, comminution of the odontoid fracture (type IIA), and/or inability to achieve or maintain fracture alignment with external immobilization. The treatment of isolated type I odontoid fractures with cervical immobilization is recommended, resulting in fusion rates approaching 100%. Anterior and posterior surgical fixation and fusion of type II and III odontoid fractures have been reported with fusion rates exceeding 90% with low morbidity. The management of odontoid fractures in elderly patients is associated with increased failure rates, and higher rates of morbidity and mortality irrespective of the treatment offered.
Traumatic Spondylolisthesis of the Axis
There is no Class I or Class II medical evidence in the literature addressing the management of traumatic spondylolisthesis of the axis. Class III medical evidence supports a variety of treatments for these injuries. The majority of Hangman fractures heal with 12 weeks of cervical immobilization with either a rigid cervical collar or a halo immobilization device. Surgical stabilization is an option in the treatment of Hangman fractures and is typically reserved for cases of severe angulation, disruption of the C2-3 disk space, or inability to establish or maintain fracture alignment with external immobilization.
Fractures of the Axis Body (Miscellaneous Axis Fractures)
There is no Class I or Class II medical evidence in the literature addressing the management of traumatic fractures of the axis body. Class III medical evidence supports the use of external immobilization as the initial treatment strategy for the variety of traumatic fractures of the C2 body.
KEY ISSUES FOR FUTURE INVESTIGATION
More data are necessary to determine the definitive management of odontoid fractures. For type I and III fractures, a well-designed multicenter case-control study could provide Class II medical evidence to define their appropriate management in the early postinjury period. For type II fractures, the literature suggests that both operative management and nonoperative management remain treatment options. A randomized analysis or a case-control study would be of benefit in establishing definitive treatment recommendations for this fracture type.
Traumatic spondylolisthesis of the axis and miscellaneous axis fractures are treated successfully with external immobilization in the majority of cases. A multicenter case-control study of patients with these injury types would help to define optimal treatments for each specific fracture subtype.
The authors have no personal financial or institutional interest in any of the drugs, materials, or devices described in this article.
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Keywords:Copyright © by the Congress of Neurological Surgeons
Axis fractures; Hangman fractures; Odontoid fractures