Management of Acute Combination Fractures of the Atlas and Axis in Adults
Ryken, Timothy C. MD, MS*; Hadley, Mark N. MD‡; Aarabi, Bizhan MD, FRCSC§; Dhall, Sanjay S. MD¶; Gelb, Daniel E. MD‖; Hurlbert, R. John MD, PhD, FRCSC#; Rozzelle, Curtis J. MD**; Theodore, Nicholas MD‡‡; Walters, Beverly C. MD, MSc, FRCSC‡,§§
*Iowa Spine & Brain Institute, University of Iowa, Waterloo/Iowa City, Iowa
‡Division of Neurological Surgery and
**Division of Neurological Surgery, Children's Hospital of Alabama, University of Alabama at Birmingham, Birmingham, Alabama
§Department of Neurosurgery and
‖Department of Orthopaedics, University of Maryland, Baltimore, Maryland
¶Department of Neurosurgery, Emory University, Atlanta, Georgia
#Department of Clinical Neurosciences, University of Calgary Spine Program, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
‡‡Division of Neurological Surgery, Barrow Neurological Institute, Phoenix, Arizona
§§Department of Neurosciences, Inova Health System, Falls Church, Virginia
Correspondence: Mark N. Hadley, MD, FACS, UAB Division of Neurological Surgery, 510 – 20th St S, FOT 1030, Birmingham, AL 35294-3410. E-mail: firstname.lastname@example.org
The treatment of combination atlas-axis fractures based primarily on the specific characteristics of the axis fracture is recommended.
* External immobilization of most C1-C2 combination fractures is recommended.
* C1-type II odontoid combination fractures with an atlanto-dental ratio of ≥ 5 mm and C1-Hangman combination fractures with C2-C3 angulation of ≥ 11 should be considered for surgical stabilization and fusion.
The unique anatomy and relationship of the atlas and axis vertebra result in a variety of fracture patterns in the setting of significant cervical trauma. Although each of these vertebral bodies is subjected to isolated fractures, combination fractures occur with sufficient frequency to warrant special consideration. Recommendations for the management of acute combination fractures of the atlas and axis were published by 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 in 2002.1 The previous guideline was based on Class III medical evidence and recommended that management decisions for combination C1-C2 fractures be based on the fracture characteristics of the axis fracture. The purpose of the current review is to update the medical evidence on the management of acute combination fractures of the atlas and axis in adults.
A National Library of Medicine (PubMed) computerized literature search from 1966 to 2011 was undertaken using Medical Subject Headings in combination with “vertebral fracture”: “atlas,” “axis,” and “human.” This strategy yielded 202 references. The abstracts were reviewed, and articles focusing on clinical management and follow-up of combination fractures of the atlas and axis were selected for inclusion. The relative infrequency of these fractures, the small number of case series, and the numerous case reports with pertinent information required rather broad inclusion criteria. The bibliographies of the selected papers were reviewed to provide additional references.
These efforts resulted in 47 manuscripts describing the clinical features and the management of acute traumatic atlas and axis combination fractures and are summarized in Evidentiary Table format. All provide Class III medical evidence.
The historic series of 46 atlas fractures described by Sir Geoffrey Jefferson2 contained 19 fractures that were actually combination fractures of the atlas and the axis (Table 1). The incidence of concurrent atlas and odontoid fracture ranges from 5% to 53% in the literature, and the incidence of combination atlas and Hangman fractures ranges from 6% to 26%.
Gleizes et al3 compiled incidence data over a 14-year period on combination fracture injuries in the upper cervical spine. The authors concluded that combination fractures are relatively common and require a high level of surveillance to detect. They identified 784 cervical spine injuries, including 116 upper cervical spine injuries. Of these, 31 were combined C1-C2 fractures, representing 4% of the total. The most frequent C1-C2 fracture combinations included combined bipedicular fracture of the axis and odontoid fracture, combined fracture of the posterior arch of C1 and odontoid fracture, combined Jefferson fracture with odontoid fracture, and C2 articular pillar fracture with odontoid fracture. The authors observed that 70% of atlas fractures, 30% of odontoid fractures, and 30% of C2 traumatic spondylolistheses (Hangman fractures) were involved in a combination fracture injury. It has been suggested that the likelihood of a neurological deficit is greater with combination fractures than with either atlas or axis fractures alone.4-6 Historically, combination fractures of C1 and C2 have been managed sequentially, as proposed by Levine and Edwards,7 allowing 1 fracture to heal (usually the atlas) before attempting definitive management of the axis injury.
In 1989, Dickman et al8 reported their experience with 25 cases of acute atlas-axis combination fractures from an overall series of 860 patients with acute cervical spinal fracture injuries (3%). They identified an incidence of neurological deficit of 12%. Four combination atlas-axis fracture types were identified: C1-type II odontoid (10 cases, 40%), C1-miscellaneous axis fracture (7 cases, 28%), C1-type III odontoid (5 cases, 20%) and C1-Hangman fracture (3 cases, 12%). Rigid immobilization was the initial management strategy in 20 of 25 of patients (84%) for a median duration of 12 weeks (range, 10-22 weeks). The reported fusion rate of was 95% (19 of 20). Five patients were treated surgically, and all achieved fusion (100%). Four were treated with early surgery based on an atlantoaxial interval of ≥ 6 mm, and 1 patient with an initial atlantoaxial interval of 5 mm failed halo treatment requiring posterior C1-C2 fusion. The authors recommend computed tomography in all patients with either a C1 or a C2 fracture to evaluate for a combination injury. They recommend that atlas fractures in combination with type II or III odontoid fractures with an atlantoaxial interval of ≥ 5 mm be considered for early surgical management.
Guiot and Fessler9 in 1999 described a series of 10 patients with combination atlas-axis fractures ultimately treated with surgical stabilization with anterior odontoid fixation. Five had failed a previous attempt at halo immobilization. There were 9 C1-type II odontoid fractures and 1 C1-type III odontoid combination fracture injury. There was 1 death unrelated to surgery. All surviving patients achieved fusion. The authors recommended that surgery be considered in patients with fractures that were irreducible or could not be maintained with external immobilization and for unstable fractures with a high likelihood of nonunion.
Treatment of Combination C1-Type II Odontoid Fractures
The treatment of specific C1-C2 fracture combinations has been the subject of numerous reports. Similar to the literature on isolated type II odontoid fracture management (see Management of Isolated Axis Fractures in Adults), the C1-type II odontoid fracture combination fracture injury has generated the most controversy. Options for management of C1-type II odontoid combination fractures include traction followed by immobilization, semirigid immobilization (collar), rigid immobilization (halo, Minerva, sterno-occipital mandibular immobilizer), posterior C1-C2 fusion with and without instrumentation, and anterior odontoid screw fixation.
Several authors have described traction followed by semirigid immobilization as treatment for acute combination C1-C2 fractures.10,11 Esses et al12 described the successful treatment of a C1-type II odontoid combination fracture managed in a cervical collar. The decreased union rate reported for type II odontoid fractures managed with nonrigid immobilization must be considered. The majority of reports of combination C1-C2 fractures have described treatment with rigid external immobilization, including the halo, sterno-occipital mandibular immobilizer, and Minerva devices.8,13-15,47,49 Dickman et al8 treated 6 patients with < 6-mm atlanto-dens interval with halo immobilization and reported an 83% success rate (5 of 6). The single treatment failure had an atlantoaxial interval of 5 mm and underwent posterior C1-C2 fusion at 12 weeks after injury. Segal et al,14 Andersson et al,13 and Seybold and Bayley15 described a total of 7 additional cases of C1-type II odontoid combination fractures successfully treated with halo immobilization.
Three contemporary case series presenting conflicting arguments on the role of halo immobilization in the treatment of cervical spinal fracture injuries are summarized in Table 2.16-18 None of these citations contain exclusively C1- C2 combination fractures, thus limiting their use for specific recommendations. They are included to provide perspective on the role of halo immobilization in upper cervical spine fracture management. Longo et al17 conducted an extensive systematic review on halo vest management of cervical spine injuries. They identified 47 reports describing a total of 1078 patients with cervical spine fractures, including 50 patients with combination C1-C2 fracture injuries (4.6%). Although the specifics of outcome with this subgroup were not presented, the authors concluded after review that the management of upper cervical spine injuries, including combination fracture injuries, with halo immobilization is a safe and effective treatment option. Daentzer and Flörkemeier16 retrospectively reviewed 29 patients with upper cervical spine injuries treated in a halo vest. They divided the patients into 2 groups: patients < 65 years of age (n = 18) and patients ≥ 65 years of age (n = 11). The fracture subtypes were as follows: type II odontoid fracture (6 patients), type III odontoid fracture (6 patients), combination C1-C2 fractures (6 patients), and other subaxial cervical fractures (11 patients). The outcomes of interest were the clinical and radiological results, treatment complications, and rate of nonunion requiring surgery. Only 2 patients required surgery: 1 patient with an isolated type II odontoid fracture and 1 patient with a type II odontoid fracture in combination with a C1 arch fracture. Both were > 65 years of age. The clinical and radiological results were not statistically significantly different between the 2 patient groups. The incidence of complications and the time interval for fracture healing were greater in the older patient group but were not statistically significant.
TABLE 2-a Evidentiar...Image Tools
In a more focused study, Tashjian et al18 reviewed 78 patients > 65 years of with odontoid fractures: isolated type II (n = 50) or isolated type III odontoid fractures (n = 17) and combination C1-C2 odontoid fractures (n = 11) treated with halo immobilization. Treatment included collar (n = 27), halo (n = 34), and operative (n = 17) (4 operation plus halo). Combination fracture outcomes were not specifically described. There were 24 deaths (31%) during the initial hospitalization. Of those patients treated with a halo vest, 42% died compared with a 20% mortality rate among patients not treated in a halo device (P = .03). The incidence of major complications in the halo-treated group was 66% compared with 36% in the nonhalo group (P = .003). The authors concluded that odontoid fractures in the elderly are associated with significant morbidity and mortality and appear to be magnified with the use of a halo immobilization device.
C1-type II odontoid combination fractures considered to be unstable have been successfully managed with surgical stabilization and fusion. Techniques have included posterior C1-C2 fixation (with or without transarticular screws), anterior odontoid screw fixation, and occipitocervical fusion. Dickman et al,8 Andersson et al,13 Coyne et al,19 and Lee et al20 treated a total of 8 patients with C1-type II odontoid combination fractures with early surgical fusion based on an atlantoaxial interval of ≥ 6 mm. Six patients had posterior C1-C2 fusion, and 1 patient underwent occipital-cervical fusion for multiple fractures of the posterior atlantal arch. Occipitocervical fixation has been used to treat C1-C2 combination fractures by other authors in cases of C1 posterior arch incompetence or gross C1-C2 instability.8,13 Guiot and Fessler9 described 2 patients with this combination injury pattern treated posteriorly with C1-C2 transarticular screw fixation and fusion. Multiple authors have reported anterior odontoid fixation with fusion rates exceeding 90%. Montesano et al,21 Berlemann and Schwazenbach,55 Guiot and Fessler,9 Henry et al,22 and Apostolides et al23 have reported a combined total of 25 patients with C1-C2 combination fractures treated successfully with anterior odontoid fixation. Cases reported by Guiot and Fessler9 and Apostolides et al23 describe the use of anterior transarticular fixation for combination C1-C2 fracture injuries.
More recently, Ben Aïicha et al24 described the surgical management of 4 patients with combination fractures of the type II odontoid and C1 arch. Two patients were treated with posterior transarticular C1-2 fusion, 1 patient with occipitocervical fusion, and 1 patient with anterior odontoid screw fixation. The authors recommended that the management of patients with C1-C2 combination fracture injuries be based on the type of odontoid fracture and the presence of neurological injury.
Agrillo and Mastronardi25 reported the successful use of triple anterior screws (odontoid and bilateral transarticular C1-C2) in the management of a combination C1 arch-type II odontoid fracture in a 92-year-old man. The authors concluded that in presence of a potentially unstable type II odontoid fracture with a fractured posterior atlas arch, triple anterior screw fixation is an option, even in the elderly.
Omeis et al26 described their surgical series of 29 elderly patients with odontoid fractures (type II alone, n = 24; type II in combination with C1 fractures, n = 5) with a mean follow-up of 18 months postoperatively. Twenty-seven patients (93%) were neurologically intact, and 2 patients (7%) presented with a central cord syndrome. Anterior odontoid screw fixation was the treatment offered to 16 patients (55%). Fusion occurred in 6 patients (37.5%); stability occurred in 9 patients (56.2%); and 1 patient (6.3%) required subsequent posterior stabilization and fusion. Posterior fixation and fusion were the initial treatment in 13 patients (45%). Fusion occurred in 4 patients (30.7%), and stability was achieved in 9 patients (69%). The authors reported 1 death and 3 other perioperative complications (10%). Twenty-five of 29 patients (86%) reportedly returned to their previous level of activity. The authors concluded that odontoid fractures in the elderly can be treated surgically with acceptable morbidity and mortality and that the majority of patients can return to their previous level of independence.
In summary, treatment options for C1-type II odontoid combination fractures include external orthoses (both nonrigid and rigid) and surgical fixation with fusion. C1-C2 instability defined by an atlantal-dens interval of ≥ 5 mm or the failure of external immobilization warrants consideration for surgical treatment by one of several acceptable means.
Treatment of Combination C1-Type III Odontoid Fractures
Dickman et al8 described 5 patients with C1-type III odontoid combination fractures. All were successfully treated with halo immobilization for an average of 12 weeks. Ekong et al27 identified 2 similar cases. One was managed successfully in a halo device; the second failed halo immobilization and required a delayed posterior C1-C2 fusion. Omeis et al26 reported a patient with a C1-type III odontoid-Hangman combination fracture that they successfully treated with ventral odontoid screw fixation followed by posterior pedicle screw fixation and fusion. It appears that external immobilization is effective in the management of these injuries in the majority of patients.
Treatment of Combination C1-Hangman Fractures
The combination of C1-Hangman fractures has been successfully treated with external immobilization in the majority of reported cases. Successful treatment with immobilization has been reported with a cervical collar,28 the halo device, and the sterno-occipital mandibular immobilizer-type orthosis.4,8,29-31 The report by Fielding et al32 included 15 patients with combination C1-Hangman fractures. They reported that when the combination Hangman fracture was associated with C2-3 angulation > 11°, they considered these C1-C2 combination injuries unstable. Surgical stabilization and fusion were recommended.
Treatment of Combination C1-Miscellaneous C2 Body Fractures
The recommended initial treatment of C1-C2 body fractures as reported in the literature is nonoperative. Both rigid immobilization and nonrigid immobilization have been described with nearly universal success.6,20,33-35 The Dickman et al8 series, which included 7 patients with combination C1-C2 body fractures were all successfully treated with either halo or sterno-occipital mandibular immobilizer immobilization.
Combination fractures of the atlas and axis occur relatively frequently and are associated with an increased incidence of neurological deficit compared with either isolated C1 or isolated C2 fractures. C1-type II odontoid combination fractures are the most common C1-C2 combination fracture injury pattern, followed by C1-miscellaneous axis body fractures, C1-type III odontoid fractures, and C1-Hangman combination fractures. Class III medical evidence addressing the management of patients with acute traumatic combination atlas and axis fractures describes a variety of treatment strategies for these unique fracture injuries based primarily on the specific characteristics of the axis fracture injury subtype.
The type of axis fracture present generally dictates the management strategy for the C1-C2 combination fracture injury. Rigid external immobilization is typically recommended as the initial management for the majority of patients with these injuries. Combination atlas-axis fractures with an atlantoaxial interval of ≥ 5 mm or angulation of C2 on C3 of ≥ 11° have been considered for and successfully treated with surgical stabilization and fusion. Surgical options in the treatment of combination C1-C2 fractures include posterior C1-2 internal fixation and fusion or combination anterior odontoid and C1-2 transarticular screw fixation with fusion. Fractures of the posterior ring of the atlas can complicate the surgical treatment of unstable C1-C2 combination fracture injuries. If the posterior arch of C1 is incompetent and a dorsal operative procedure is indicated, occipitocervical internal fixation and fusion, posterior C1-C2 transarticular screw fixation and fusion, and C1 lateral mass-C2 pars/pedicle screw fixation and fusion techniques have been reported to be successful.
KEY ISSUES FOR FUTURE INVESTIGATION
Review of the available literature highlights the lack of prospective data and comparison studies to help guide appropriate treatment of combination atlas-axis fractures. Although immobilization has been recommended as the initial management of choice, the increased morbidity and mortality of halo use in the elderly, the increased rate of nonunion of type II odontoid fractures, and patient preferences all raise the question of the benefit of early surgical fixation and fusion for these injuries. Prospective data derived from appropriately designed comparative studies would assist in determining the most favorable outcome strategies and would provide Class II medical evidence on this topic.
The authors have no personal financial or institutional interest in any of the drugs, materials, or devices described in this article.
1. Management of combination fractures of the atlas and axis in adults. In: Guidelines for the management of acute cervical spine and spinal cord injuries. Neurosurgery. 2002;50(3 suppl):S140–S147.
2. Jefferson G. Fractures of the atlas vertebra: report of four cases and a review of those previously reported. Br J Surg. 1920;7:407–422.
3. Gleizes V, Jacquot FP, Signoret F, Feron JM. Combined injuries in the upper cervical spine: clinical and epidemiological data over a 14-year period. Eur Spine J. 2000;9(5):386–392.
4. Zavanone M, Guerra P, Rampini P, Crotti F, Vaccari U. Traumatic fractures of the craniovertebral junction: management of 23 cases. J Neurosurg Sci. 1991;35(1):17–22.
5. Fowler JL, Sandhu A, Fraser RD. A review of fractures of the atlas vertebra. J Spinal Disord. 1990;3(1):19–24.
6. Fujimura Y, Nishi Y, Chiba K, Kobayashi K. Prognosis of neurological deficits associated with upper cervical spine injuries. Paraplegia. 1995;33(4):195–202.
7. Levine AM, Edwards CC. Treatment of injuries in the C1-C2 complex. Orthop Clin North Am 1986;17(1):31–44.
8. Dickman CA, Hadley MN, Browner C, Sonntag VK. Neurosurgical management of acute atlas-axis combination fractures: a review of 25 cases. J Neurosurg. 1989;70(1):45–49.
9. Guiot B, Fessler RG. Complex atlantoaxial fractures. J Neurosurg 1999;91(2 suppl):139–143.
10. Seeman E, Bianchi G, Khosla S, Kanis JA, Orwoll E. Bone fragility in men: where are we? Osteoporos Int. 2006;17(11):1577–1583.
11. Sherk HH. Fractures of the atlas and odontoid process. Orthop Clin North Am. 1978;9(4):973–984.
12. Esses S, Langer F, Gross A. Fracture of the atlas associated with fracture of the odontoid process. Injury. 1981;12(4):310–312.
13. Andersson S, Rodrigues M, Olerud C. Odontoid fractures: high complication rate associated with anterior screw fixation in the elderly. Eur Spine J. 2000;9(1):56–59.
14. Segal LS, Grimm J, Stauffer E. Non-union of fractures of the atlas. J Bone Joint Surg. 1987;69(9):1423–1434.
15. Seybold EA, Bayley JC. Functional outcome of surgically and conservatively managed dens fractures. Spine (Phila Pa 1976). 1998;23(17):1837–1845; discussion 1845-1846.
16. Daentzer D, Flörkemeier T. Conservative treatment of upper cervical spine injuries with the halo vest: an appropriate option for all patients independent of their age? J Neurosurg Spine. 2009;10(6):543–550.
17. Longo UG, Denaro L, Campi S, Maffulli N, Denaro V. Upper cervical spine injuries: indications and limits of the conservative management in Halo vest: a systematic review of efficacy and safety. Injury. 2010;41(11):1127–1135.
18. Tashjian RZ, Majercik S, Biffl WL, Palumbo MA, Cioffi WG. Halo-vest immobilization increases early morbidity and mortality in elderly odontoid fractures. J Trauma. 2006;60(1):199–203.
19. Coyne TJ, Fehlings MG, Wallace MC, Bernstein M, Tator CH. C1-C2 posterior cervical fusion: long-term evaluation of results and efficacy. Neurosurgery. 1995;37(4):688–692; discussion 692-693.
20. Lee TT, Green BA, Petrin DR. Treatment of stable burst fracture of the atlas (Jefferson fracture) with rigid cervical collar. Spine (Phila Pa 1976). 1998;23(18):1963–1967.
21. Montesano PX, Anderson PA, Schlehr F, Thalgott JS, Lowrey G. Odontoid fractures treated by anterior odontoid screw fixation. Spine (Phila Pa 1976). 1991;16(3 suppl):S33–S37.
22. Henry AD, Bohly J, Grosse A. Fixation of odontoid fractures by an anterior screw. J Bone Joint Surg Br. 1999;81(3):472–477.
23. Apostolides PJ, Theodore N, Karahalios DG, Sonntag VK. Triple anterior screw fixation of an acute combination atlas-axis fracture: case report. J Neurosurg. 1997;87(1):96–99.
24. Ben Aïcha K, Laporte C, Akrout W, Atallah A, Kassab G, Jégou D. Surgical management of a combined fracture of the odontoid process with an atlas posterior arch disruption: a review of four cases. Orthop Traumatol Surg Res. 2009;95(3):224–228.
25. Agrillo U, Mastronardi L. Acute combination fracture of atlas and axis: “triple” anterior screw fixation in a 92-year-old man: technical note. Surg Neurol. 2006;65(1):58–62.
26. Omeis I, Duggal N, Rubano J, et al.. Surgical treatment of C2 fractures in the elderly: a multicenter retrospective analysis. J Spinal Disord Tech. 2009;22(2):91–95.
27. Ekong CE, Schwartz ML, Tator CH, Rowed DW, Edmonds VE. Odontoid fracture: management with early mobilization using the halo device. Neurosurgery. 1981;9(6):631–637.
28. Coric D, Wilson JA, Kelly DL Jr. Treatment of traumatic spondylolisthesis of the axis with nonrigid immobilization: a review of 64 cases. J Neurosurg. 1996;85(4):550–554.
29. Brashear R Jr, Venters G, Preston ET. Fractures of the neural arch of the axis: a report of twenty-nine cases. J Bone Joint Surg Am. 1975;57(2):879–887.
30. Elliott JM Jr, Rogers LF, Wissinger JP, Lee JF. The Hangman’s fracture: fractures of the neural arch of the axis. Radiology. 1972;104(2):303–307.
31. Govender S, Charles RW. Traumatic spondylolisthesis of the axis. Injury. 1987;18(5):333–335.
32. Fielding JW, Francis WR Jr, Hawkins RJ, Pepin J, Hensinger R. Traumatic spondylolisthesis of the axis. Clin Orthop Relat Res. 1989;239:47–52.
33. Polin RS, Szabo T, Bogaev CA, Replogle RE, Jane JA. Nonoperative management of types II and III odontoid fractures: the Philadelphia collar versus the halo vest. Neurosurgery. 1996;38(3):450–456; discussion 456-457.
34. Craig JB, Hodgson BF. Superior facet fractures of the axis vertebra. Spine (Phila Pa 1976). 1991;16(8):875–877.
35. Bohay D, Gosselin RA, Contreras DM. The vertical axis fracture: a report on three cases. J Orthop Trauma. 1992;6(4):416–419.
36. Müller EJ, Wick M, Muhr G. Traumatic spondylolisthesis of the axis: treatment rationale based on the stability of the different fracture types. Eur Spine J. 2000;9(2):123–128.
37. Morandi X, Hanna A, Hamlat A, Brassier G. Anterior screw fixation of odontoid fractures. Surg Neurol. 1999;51(3):236–240.
38. Greene KA, Dickman CA, Marciano FF, Drabier JB, Hadley MN, Sonntag VK. Acute axis fractures: analysis of management and outcome in 340 consecutive cases. Spine (Phila Pa 1976). 1997;22(16):1843–1852.
39. Weller SJ, Malek AM, Rossitch E Jr. Cervical spine fractures in the elderly. Surg Neurol. 1997;47(3):274–280; discussion 280-281.
40. Pedersen AK, Kostuik JP. Complete fracture-dislocation of the atlantoaxial complex: case report and recommendations for a new classification of dens fractures. J Spinal Disord. 1994;7(4):350–355.
41. Hanigan WC, Powell FC, Elwood PW, Henderson JP. Odontoid fractures in elderly patients. J Neurosurg. 1993;78(1):32–35.
42. Hays MB, Alker GJ Jr. Fractures of the atlas vertebra: the two-part burst fracture of Jefferson. Spine (Phila Pa 1976). 1988;13(6):601–603.
43. Jeanneret B, Magerl F. Primary posterior fusion C1/2 in odontoid fractures: indications, technique, and results of transarticular screw fixation. J Spinal Disord. 1992;5(4):464–475.
44. Ryan MD, Henderson JJ. The epidemiology of fractures and fracture-dislocations of the cervical spine. Injury. 1992;23(1):38–40.
45. Kesterson L, Benzel E, Orrison W, Coleman J. Evaluation and treatment of atlas burst fractures (Jefferson fractures). J Neurosurg. 1991;75(2):213–220.
46. Levine AM, Edwards CC. Fractures of the atlas. J Bone Joint Surg Am. 1991;73(5):680–691.
47. Govender S, Charles RW. Fracture of the dens in ankylosing spondylitis. Injury. 1987;18(3):213–214.
48. Hanssen AD, Cabanela ME. Fractures of the dens in adult patients. J Trauma. 1987;27(8):928–934.
49. Lind B, Nordwall A, Sihlbom H. Odontoid fractures treated with halo-vest. Spine (Phila Pa 1976). 1987;12(2):173–177.
50. Levine AM, Edwards CC. The management of traumatic spondylolisthesis of the axis. J Bone Joint Surg Am. 1985;67(2):217–226.
51. Pepin JW, Bourne RB, Hawkins RJ. Odontoid fractures, with special reference to the elderly patient. Clin Orthop Relat Res. 1985;193:178–183.
52. Effendi B, Roy D, Cornish B, Dussault RG, Laurin CA. Fractures of the ring of the axis: a classification based on the analysis of 131 cases. J Bone Joint Surg Br. 1981;63-B(3):319–327.
53. Lipson SJ. Fractures of the atlas associated with fractures of the odontoid process and transverse ligament ruptures. J Bone Joint Surg Am. 1977;59(2):940–943.
54. Anderson LD, D'Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg Am. 1974;56(8):1663–1674.
55. Berlemann U, Schwarzenbach O. Dens fractures in the elderly. Results of anterior screw fixation in 19 elderly patients. Acta Orthop Scand. 1997;68(4):319–224.
56. Fujimura Y, Nishi Y, Kobayashi K. Classification and treatment of axis body fractures. J Orthop Trauma. 1996;10(8):536–540.
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