The technical issue of whether one or two screws are needed has been addressed in
various studies [25, 115, 188].Although there is a theoretical advantage of prevent-
ing rotation with two screws, there is no increased strength for bending move-
ments and no difference in successful bony fusion. Although two screws are theo-
retically desirable, fixation with one screw is sufficient with adequate technique
[115, 188] (
Case Study 1
). Apfelbaum et al. [25] compared anterior screw fixation
for recent and remote odontoid fractures in 147 patients at two institutions (138
Type II, 9 Type III). Anterior screw fixation was performed either within 6 months
of injury or more than 18 months after injury. At a mean follow-up of 18 months,
the fusion rates were 88% and 25%,respectively. These results indicate that remote
dens fractures do not favorably respond to anterior screw fixation. An alternative
technique for augmentation or salvage procedures of failed anterior screw fixation
is an anterior atlantoaxial screw fixation (
Fig. 16e, f
).
Dislocated Type II and Type
IIA fractures are indications
for surgery
In cases with remote dens fractures, dens non-union, os odontoideum or
elderly patients with osteoporosis, a posterior approach is more likely to be suc-
cessful. The classical treatment is a posterior instrumented fusion according to
abc
d
Case Study 1
This 51-year-old male patient fell from his mountain bike and complained
about neck pain. On admission, the patient was neurologically intact (ASIA E).
Standard anteroposterior and lateral (
a) radiographs demonstrated a Type II
odontoid fracture. The sagittal CT reconstruction confirmed the diagnosis of

the fracture at the base of the odontoid process (
b). Repositioning and anterior
stabilization with a single screw was performed. Follow-up radiographs (
c, d)
demonstrated an anatomical reduction of the fracture and bony healing.
858 Section Fractures
ab
cd
ef
gh
Figure 17. Posterior atlantoaxial stabilization techniques
Posterior C1/2 fusion according to a, b Brooks and c, d Gallie. e, f Transarticular atlantoaxial screw fixation according to
Magerl [113] with additional wire cerclage and fusion with a bicortical bone graft.
g, h Alternative screw-rod fixation
according to Harms [96].
Cervical Spine Injuries Chapter 30 859
Gallie or Brooks (Fig. 17a–d). The drawback of these fusion techniques is the lack
of primary stability increasing the rate of non-union. Posterior atlantoaxial
transaxial screw fixation and fusion (
Fig. 17e, f) according to Magerl [113] pro-
vides the highest chance of successful fusion. Harms et al. [96] have described an
alternativefixationmethodfortheatlantoaxialjointcomplex,i.e.,aposterior
atlas and axis screw-rod fixation and fusion (
Fig. 17g, h)(Case Study 2). In a
recent review [5], 8 papers describe a total of 147 patients who underwent poste-
rior cervical fixation and fusion for Type II dens fractures and 29 patients treated
similarly for Type III fractures. The overall fusion rate for fractures managed
with surgical fixation and fusion was 87% (Type II) and 100% (Type III), respec-
tively.
Management in the Elderly Patient

Posterior instrumented
fusion is indicated for Type II
fractures in the elderly
The management of odontoid fractures in the elderly patient remains controver-
sial. Ryan and Taylor [167] described 30 patients 60 years and older with Type II
odontoid fractures. The fusion success rate in patients older than 60 years treated
with external immobilization was only 23%. Similarly, Andersson et al. [24]
described 29 patients 65 years and older with odontoid fractures managed by
surgical and non-surgical means. In their series, six (86%) of seven patients
achieved successful fusion after posterior cervical C1–C2 arthrodesis. Patients
treated with anterior odontoid screw fixation had a fusion rate of 20% and
patients managed with external immobilization alone had a fusion rate of 20%.
Pepin et al. [152] reported their experience with 41 acute odontoid fractures and
found that halo immobilization was poorly tolerated in patients 75 years and
older. They suggested that early C1–C2 fixation and fusion was appropriate in
this group. In a recent review [5], three case series argued against surgical fixa-
tion in the elderly patient whereas seven other case series favor surgical fixation
in this age group. One case-control study by Lennarson et al. [125] provides Class
II medical evidence for surgical treatment of elderly patients. This study exam-
ined 33 patients with isolated Type II odontoid fractures treated with halo vest
immobilization. The authors found that patients older than50 years had a signifi-
cantly increased failure rate of fusion in a halo immobilization device (21 times
higher) when compared to patients younger than 50 years. Other factors such as
medical conditions, sex of the patient, degree of fracture displacement, direction
of fracture displacement, length of hospital stay, or length of follow-up did not
influence outcome.
Traumatic Spondylolisthesis of the Axis
Traumatic fractures of the posterior elements of the axis may occur after hyper-
extension injuries as seen in motor vehicle accidents, diving, and falls or judicial
hangings [172, 210]. Therefore, the term “hangman’s fracture” was coined by

Schneider in 1965 [172]. Garber [85] described eight patients with “pedicular”
fractures of the axis after motor vehicle accidents and used the term “traumatic
spondylolisthesis” of the axis.
Classification
The classification scheme of Effendi [70] has gained widespread acceptance for
the classification of these injuries. Effendi et al. [70]described three types of frac-
tures which are mechanism based (
Fig. 18).
860 Section Fractures
Figure 18. Traumatic spondylolisthesis (hangman’s frac ture)
Type I: isolated hairline fractures of the ring of the axis with minimal displacement of the body of C2. These injuries are
caused by axial loading and hyperextension. Type II: displacement of the anterior fragment with disruption of the disc
space below the axis. These injuries are a result of hyperextension and rebound flexion. Type IIA: displacement of the
anterior fragment with the body of the axis in a flexed position without C2–C3 facet dislocation. Type III: displacement
of the anterior fragment with the body of the axis in a flexed position in conjunction with C2–C3 facet dislocation. These
injuries are caused by primary flexion and rebound extension.
In the series reported by Effendi [70], Type I fractures were the most prevalent
(65%) while Type II (28%) and Type III fractures(7%)werelesscommon.In
1985, Levine and Edwards [127] modified Effendi’s classification scheme by add-
ing a subtype Type IIA (flexion/distraction injury). However, not all axis frac-
tures can be classified according to this scheme [39]. Fujimura et al. [83] used
radiological criteria to classify axis body fractures into: avulsion, transverse,
burst, or sagittal fracture.
Treatment
Most fractures heal within
12 weeks of external
immobilization
Most patients with traumatic spondylolisthesis reported in the literature were
treatedwithcervicalimmobilizationwithgoodresults[5].Importantly,thereis
no Class I or Class II evidence that addresses the management of traumatic spon-

dylolisthesis of the axis [5]. Fractures of the axis body can mostly be treated non-
operatively [5, 91]. Most traumatic spondylolisthesis heals with 12 weeks of cer-
vical immobilization with either a rigid cervical collar or a halo immobilization
device.
Surgical stabilization is an
optioninTypeIIandIII
fractures
Surgical stabilization is a preferred treatment option in cases with:
severe angulation (Effendi Type II)
disruption of the C2–C3 disc space (Effendi Type II and III)
inability to establish or maintain fracture alignment with external immobili-
zation
Axis body fractures are
usually treated conservatively
Surgical options for unstable traumatic spondylolisthesis include anterior C2/3
interbody fusion with anterior plate fixation (
Case Introduction) and posterior
techniques such as direct screw fixation of the posterior arch [117]. In the series
by Effendi et al. [70], 42 of 131 patients with hangman’s fractures were treated
surgically (10 anterior C2–C3 fusion and 32 posterior fusion). All were success-
fullystabilizedatlatestfollow-up.InthestudybyFrancisetal.[78],only7of123
patients with hangman’s fractures were treated surgically (4 anterior C2–C3
fusion, 2 posterior C1–C3 fusion, and 1 posterior C2–C4 fusion). The authors
report that 6 of the 7 patients demonstrated a C2–C3 angulation of more than
Cervical Spine Injuries Chapter 30 861
abc
d
e f
gh
i

j
Case Study 2
This 47-year-old male patient fell from a
donkey at the age of 12 years. Neurologi-
cal symptoms started at the age of
26 years. He recently presented with signs
of chronic central cord compression,
spasticity and gait difficulties (ASIA D).
The sagittal CT reconstruction (
a) dem-
onstrates a pseudarthrosis of the odonto-
id process. The MRI (
b)showsthecom-
pression of the spinal cord at the level of
the pseudarthrosis. Flexion/extension ra-
diographs (c, d) were taken during the
operation and demonstrate the impor-
tant atlantoaxial instability. Dorsal fusion
of C1/C2 was performed according to the
technique of Harms [96]; in addition lami-
nectomy of C1 was performed. The intra-
operative radiographs (
e, f)showthere-
position and the position of the hardware
as well as the needles used for the intraoperative neurological monitoring (
e). The postoperative CT scan demonstrates
the reposition of the odontoid process in the anteroposterior view (
g) and lateral view (h), the position of the pedicle
screw in C1 (
i) and C2 (j), as well as the laminectomy of C1 (i).

862 Section Fractures
11 degrees. All seven patients achieved bony stability. A number of case series of
hangman’s fractures offer similar experiences with surgical management [5].
Combined Atlas/Axis Fractures
The occurrence of the fractures in combination often implies a more significant
structural and mechanical injury. Combination fractures of the C1–C2 complex
arerelativelycommon[7].Inreportsfocusingprimarilyonodontoidfractures,
the occurrence of a concurrent C1 fracture in the presence of a Type II or Type III
odontoid fracture has been reported in 5–53% of cases. Odontoid fractures have
been identified in 24–53% of patients with atlas fractures. In the presence of a
hangman’s fracture, the reported incidence of a C1 fracture ranges from 6% to
26% [7].
A higher incidence of neurological deficit is associated with combined atlas
and axis fractures. The atlas–Type II odontoid combination fracture seems to
be the most common combination injury subtype, followed by atlas–miscella-
neous axis, atlas-Type III odontoid, and atlas–traumatic spondylolisthesis frac-
tures.
Treatment
The axis fracture
characteristics commonly
dictate the management
Reports of combined atlas/axis fractures are relatively rare and no treatment
guidelines but only recommendations can be derived from the literature [7].
Treatment of combined atlas-axis fractures is based primarily on the specific
characteristics of the axis fracture. External immobilization is recommended for
most combined atlas/axis fractures. Combined atlas–Type II odontoid fractures
with an atlantodental interval of more than 4 mm and atlas–traumatic spondylo-
listhesis injuries with angulation of more than 10 degrees should be considered
for surgical stabilization and fusion. The surgical technique must in some cases
be modified as a result of loss of the integrity of the ring of the atlas. In most cir-

cumstances, the specifics of the axis fracture will dictate the most appropriate
management of the combination fracture injury. The integrity of the ring of the
atlas must often be taken into account when planning a specific surgical strategy
using instrumentation and fusion techniques. In cases where the posterior arch
of C1 is not intact, both incorporation of the occiput into the fusion construct
(occipitocervical fusion) and posterior C1–C2 transarticular screw fixation and
fusion have been successful [7].
Classification and Treatment of Subaxial Injuries
In contrast to atlas and axis, the vertebrae and articulations of the subaxial cervi-
cal spine (C3–C7) have similar morphological and kinematic characteristics.
However, important differences in lateral mass anatomy and in the course of the
vertebral artery exist between the mid and lower cervical spine. Approximately
Eighty percent of all cervical
injuries affect the subaxial
spine
80% of all cervical spine injuries affect the lower cervical spine and these injuries
are often associated with neurological deficits [17, 22, 32, 182]. The variety and
heterogeneity of subaxial cervical spinal injuries require accurate characteriza-
tion of the mechanism and types of injury to enable a comparison of the efficacy
of operative and non-operative treatment strategies.
Cervical Spine Injuries Chapter 30 863
Classification
The Allen and Ferguson classification system [16] has been the most commonly
used scheme to differentiate and characterize subaxial vertebral injuries. Based
on 165 cases, Allen and Ferguson [16] described common groups for: compres-
sive flexion, vertical compression, distractive flexion, compressive extension,
distractive extension, and lateral flexion.
A systematic classification of the lower cervical spine was proposed by Aebi et
al. [12, 13] and modified by Blauth [30]. The classification is adapted from the
AO/ASIF (Association for the Study of Internal Fixation) classification scheme,

which is widely used for thoracolumbar fractures (see Chapter
31 ). The three
main groups are shown in
Table 8 and Fig. 19.
Table 8. AO Fracture Classification of lower injuries
Type A: compression
injuries
Type B: anterior and posterior
element injury with distraction
Type C: anterior and
posterior element injury
with rotation
A1.1 B1.1 C1.1
impaction of the endplate with transverse disc disruption rotational wedge fracture
A1.2 B1.2 C1.2
wedge impaction with Type A vertebral body
fracture
rotational split fracture
A1.3 B1.3 C1.3
vertebral body collapse anterior subluxation rotational burst fracture
A2.1 B2.1 C2.1
sagittal split fracture transverse bicolumn fracture B1 injury with rotation
A2.2 B2.2 C2.2
coronal split fracture transverse disruption of the disc B2 injury with rotation
A2.3 B2.3 C2.3
pincer fracture with Type A vertebral body
fracture
B3 injury with rotation
A3.1 B3.1 C3.1
incomplete burst fracture hyperextension subluxation slice fracture

A3.2 B3.2 C3.2
burst-split hyperextension spondylolysis oblique fracture
A3.3 B3.3 C3.3
complete burst fracture posterior dislocation complete separation of
the adjacent vertebrae
Types, groups, and subgroups allow for a morphology-based classification of cervical fractures
according to Aebi and Nazarian [13] and modified by Blauth et al. [30]
Thefracturetypesarerelatedtospecific injury pattern, i.e.:
injuries of the anterior elements induced by compression (Type A)
injuries of the posterior and anterior elements induced by distraction
(Ty pe B)
injuries of the anterior and posterior elements induced by rotation (Type C)
TypesBandCarethemost
common fractures
Types B and C are the most common fracture types (Table 9).
Subaxial fracture-dislocation is frequently associated with neurological injury
(
Table 10).
864 Section Fractures
Figure 19. AO Fracture Classification of subaxial injuries
According to the classification of AOSPINE (Blauth et al. [30], redrawn and modified).
Table 9. Frequency of fracture types in subaxial injuries
n= 448 Total percentage Percentage within the types
Type A 66 14.7 %
A1 13 2.9% 19– 7%
A2 9 2.0 % 13.7 %
A3 44 9.8 % 66.6%
Type B 197 43.9 %
B1 157 35.0 % 79.7%
B2 4 0.9% 2.0%

B3 36 8.0% 18.3%
Type C 185 41.2 %
C1 0 0% 0 %
C2 184 41.0 % 99.5 %
C3 1 0.2 % 0.5 %
Based on an analysis of 448 cases by Blauth et al. [30]
Cervical Spine Injuries Chapter 30 865
Table 10. Frequency of neurological deficits in subaxial injuries
Types and groups Number of patients Neurological deficit
Type A 66 42.4 %
A1 13 15.3%
A2 9 22.2%
A3 44 54.5%
Type B 197 64.4%
B1 157 61.0%
B2 4 75.0%
B3 36 73.0%
Type C 185 62.7%
C1 0 0%
C2 184 62.0 %
C3 1 100%
Total 448 60.7%
Based on an analysis of 448 cases by Blauth et al. [30]
Treatment
Non-operative Management
Most subaxial cervical
injuries can be treated
conservatively
Most subaxial spine injuries can be successfully treated by conservative means
(Philadelphia collar, Minerva cast or halo vest fixation). Treatment with traction

and prolonged bedrest has been associated with increased morbidity and mor-
tality and has widely been abandoned today. After reduction of dislocated frac-
tures, more rigid fixation techniques (halo vest fixation, Minerva cast) appear to
have better success rates than less rigid orthoses (collars, traction only).
Operative Management
Operative stabilization of unstable fractures (especially for Type B and Type C
injuries) is gaining increasing acceptance because it facilitates aftertreatment
without disturbing external supports. Indications for surgical treatment include
(
Table 11)[11]:
Table 11. Surgical indications for subaxial injuries
irreducible spinal cord compression vertebral subluxation of 20 % or more
ligamentous injury with facet instability failure to achieve anatomical reduction
(irreducible injury)
spinal kyphotic deformity more than 15° persistent instability with failure to
maintain reduction
vertebral body fracture compression of
40% or more
ligamentous injury with facet instability
Most subaxial spine injuries
can be treated by
an anterior approach
Both posterior (Fig. 20) and anterior (Fig. 21) cervical fusion techniques usually
result in spinal stability for most patients with subaxial injuries. The outcome of
anterior vs. posterior fracture fixation has been addressed in various recent
publications [14, 77, 97, 119, 133, 162, 192]. The studies include only small case
series (21 patients [77] to 35 patients [119]) and the methodology allows the clas-
sification of the studies using only Class III and Class IV [97, 192] evidence. Aebi
et al. [14] were one of the first groups to suggest that most lower cervical spine
fractures can successfully be treated by an anterior approach even in the case of

distraction and rotation injuries with posterior element involvement. Today, lit-
erature reviews indicate that anterior fixation of fractures of the lower cervical
866 Section Fractures
ab
c
d
Figure 20. Posterior fracture stabilization
a, b Lateral mass screw fixation according to the technique of Magerl [113]. The screw is directed from the medial upper
quadrant of the facet joint 20 –25° laterally and 30 –40° cranially. Polyaxial top-loading screws facilitate rod placement.
c, d After decortication of the posterior elements, a posterior fusion is added and a cross-connector used (when appro-
priate) to increase construct stability.
spine is now the preferred treatment approach. Failures of this technique which
may result in reoperations are rare (0–6%) [119, 133].
Anterior fusion should not
be performed without
plate fixation
Anterior fusion should not be performed without plate fixation (Fig. 21),
because it is associated with an increased likelihood of graft displacement and
the development of late kyphosis, particularly in patients with distractive Type B
and Type C injuries [11].
Similarly, posterior fusion that uses wiring techniques is more likely to result
in late displacements with kyphotic angulation when compared to posterior
Cervical Spine Injuries Chapter 30 867