Six Year Review of Odontoid Fractures: The Emerging Role of Surgical
C. Ziai and R. John Hurlbert
Background: Traditionally, odontoid fractures
have been treated with different bracing techniques resulting
in variable degrees of successful healing. Surgical intervention
is becoming more widely practiced as a primary intervention.
The purpose of this report was to survey our recent experience
in southern Alberta to determine potential outcome differences
in management strategies. Methods: We retrospectively
reviewed the charts of 520 patients diagnosed with cervical
spine fractures over a six-year period from January 1990, through
December 1996. Patients were identified through the medical
records database of the two Level 1 trauma facilities, on the
basis of ICD-9 diagnostic coding. Results: Ninety-three
fractures of the odontoid process were identified, of which
85 were acute and eight were chronic. There were 57 Type II
(67%) and 27 Type III (32%) acute odontoid fractures. Of these,
64 were managed conservatively (bracing), whereas 20 were treated
surgically. Thirteen patients underwent anterior screw fixation,
seven patients had posterior cervical fusion. Eleven patients
died in the acute phase, two as a result of their high cervical
cord injury and nine from unrelated medical causes. Fifty-six
of the remaining 82 patients (68%) were located with a minimum
of three months follow-up (range three months to eight years).
Satisfactory results were obtained in 76% of all acute patients
treated by bracing, but only 50% in those over the age of 65.
In the surgically managed group, all patients (100%) went on
to develop stable fusions. Conclusions: Our results
indicate that while conservative management of odontoid fractures
with external bracing results in fracture healing in most cases,
surgical fusion may provide superior rates of bony union with
acceptable morbidity. This difference in outcome lends itself
to formal investigation through a prospective randomized trial.
Revue des cas de fractures de l'apophyse odontoïde sur
une période de six ans: le rôle de la chirurgie.
Introduction: Traditionnellement, les fractures de
l'apophyse odontoïde ont été traitées
par différentes techniques de orthésiques produisant
des résultats variables. On a recours de plus en plus
à la chirurgie comme traitement initial. Le but de cet
article était d'évaluer notre expérience
récente dans le sud de l'Alberta pour déterminer
s'il existait des différences de résultats selon
les stratégies de traitement. Méthodes:
Nous avons révisé rétrospectivement sur
une période de six ans, de janvier 1990 à décembre
1996, les dossiers de 520 patients ayant un diagnostic de fracture
de la colonne cervicale. Les patients étaient identifiés
par le diagnostic codifié conformément à
la CIM-9 dans leur dossier médical contenu dans une base
de données dans les deux centres de traumatologie de
niveau 1. Résultats: 93 fractures de l'apophyse
odontoïde ont été identifiées, dont
85 étaient aigues et 8 chroniques. Il y avait 57 fractures
aiguës de type II (67%) et 27 de type III (32%). 64 patients
ont reçu un traitement conservateur (orthèse)
alors que 20 ont subi une chirurgie. 13 patients ont subi une
fixation au moyen d'une vis antérieure et 7 ont subi
une fusion cervicale postérieure. Onze patients sont
décédés en phase aiguë, deux suite
à un traumatisme haut de la moelle épinière
et neuf de causes médicales non reliées. Le suivi
chez 56 des 82 autres patients (68%) était d'au moins
trois mois (de trois mois à huit ans). Un résultat
satisfaisant a été obtenu chez 76% de tous les
cas aigus traités par orthèse, mais seulement
chez 50% des patients âgés de plus de 65 ans. Dans
le groupe qui a subi une chirurgie, tous les patients (100%)
ont éventuellement développé une fusion
stable. Conclusions: Nos résultats indiquent
que, bien que le traitement conservateur par orthèse
externe entraîne la guérison de la plupart des
fractures de l'apophyse odontoïde, la fusion chirurgicale
donne des taux supérieurs d'union osseuse et une morbidité
acceptable. Cette différence dans les résultats
peut servir de base à une investigation formelle au moyen
d'un essai randomisé.
J. Neurol. Sci. 2000; 27: 297-301
fractures account for approximately 11 percent of cervical spine
traumatic injuries.[1,2,3] The management of these fractures
remains controversial and a variety of stabilization techniques
have been employed with varying success rates. Recently, new
surgical techniques have allowed operative intervention to take
on the role of a primary treatment alternative, often preserving
motion through the atlanto-axial complex.[4,5] Following
the introduction of these techniques into our surgical practice,
we undertook to review our experience and the outcomes of our
patients during this transition period. Ninety-three odontoid
fractures treated between 1990 and 1996 were identified. The
results of long-term immobilization versus surgical intervention
are retrospectively compared.
hundred and twenty cervical spine fractures were treated at
the Foothills Hospital and Medical Centre and the Calgary General
Hospital between January 1990 and December 1996. Individual
chart review was performed on these patients to identify those
diagnosed with odontoid fractures. Subsequently, further detailed
review was undertaken to obtain information on: age, sex, cause
of injury, degree of displacement of the fracture, neurological
symptoms and status, the presence of complicating injuries and
other spinal fractures, fracture treatment and follow-up, duration
of hospitalization, and management of treatment failures. The
diagnosis of odontoid fracture was based on anterior/posterior
(AP) and lateral cervical, and open mouth odontoid radiographs.
Standard tomograms and/or computed tomography (CT) of the cervical
spine were performed for further clarification or where the
diagnosis was in doubt. Magnetic resonance imaging was not routinely
performed. Acute fractures were defined as those diagnosed within
10 days of the traumatic event, while subacute/chronic fractures
were defined as those diagnosed later than 10 days.
of 82 surviving patients (68%) were available for a minimum
of three months follow-up. This consisted of review of physician
outpatient records, direct patient reassessment where possible,
telephone interviews, and follow-up flexion-extension radiographs.
The median follow-up duration was six months with a range of
three months to eight years. Fracture stability was determined
based upon flexion-extension X-rays for all except 12 patients
who met criteria for bony union on static radiographs (loss
of cortical margins, graft incorporation, callus formation).
Nonunion was defined by the presence of radiolucency on plain
radiographs, observable movement in flexion and extension, or
patients were diagnosed with odontoid fractures within the review
period. There were 58 male and 35 female patients, with a mean
age of 57 (range 16-94 years). Eighty-five acute odontoid fractures
were identified including Type I (n=1), Type II (n=57), and
Type III (n=27) injuries. The Type I fracture occurred in a
patient with rheumatoid arthritis and required no further treatment.
Rheumatoid arthritis was not a risk factor in any other patient.
Of eight chronic fractures, there were five Type II and three
Type III injuries. Eleven deaths occurred within the first six
weeks of injury. Two patients died as a direct result of the
cervical cord injury. Seven patients died from respiratory compromise
unrelated to the odontoid fracture and two patients died of
other medical illnesses. Of the 85 patients with acute injuries,
81 were medically fit to undergo treatment (four patients were
either moribund or died prior to intervention).
causes of traumatic injury are summarized in Table
1. In the 16-34 age group (n=19) the most common mechanism
of injury was motor vehicle accidents, while in the 65-94 age
group (n=33) falls were most prevalent. Symptomatically, 66
patients presented with cervical pain, eight complained of paresthesias,
and five noted specific motor weakness or paralysis. On initial
assessment, 78 patients (84%) were neurologically intact. Two
patients were quadriplegic as a result of the odontoid fracture,
and 10 patients suffered partial spinal cord injuries. Three
patients had uncertain fracture-related neurological deficits
due to associated severe head injury. Fifteen patients (16%)
had associated significant head injury, 18 patients (19%) had
other acute cervical spine fractures, and six patients (6%)
had acute thoracic or lumbar spine fractures.
fourteen patients (15%) a delay in diagnosis ranging from one
day to four months was documented. Odontoid fracture was unrecognized
on initial cervical radiographs by the attending physician in
four cases; two patients were diagnosed after transfer from
a peripheral center where adequate imaging (CT scan) could not
be performed; four patients did not seek immediate medical attention;
and a cervical spine radiograph was not performed by the admitting
community hospital in two instances. These delays in diagnosis
did not adversely affect the neurological status of any patient.
spine radiographs were analyzed for the degree of anterior or
posterior subluxation of the odontoid peg with respect to the
body of C2, in mm. The relationship between degree of displacement
on admission to neurological deficit is shown in Table
2. The degree of dislocation ranged from 2 - 11 mm of displacement.
Posterior subluxation accounted for the largest patient group
and was most commonly associated with neurological deficit.
The two complete cord injuries both occurred in patients with
posterior displacement. No patient with a chronic fracture had
a neurological deficit despite presence of subluxation in four
fractures were treated with a course of external skeletal fixation,
13 of which underwent initial fracture reduction with skeletal
tong traction. Traction was employed for seven of the 10 partial
spinal cord injuries, one C2 root injury and five intact patients;
seven of the 13 patients placed in traction had displacement
of greater than 4 mm. Table
3 demonstrates the types of external fixation devices used
for each fracture type in the conservatively treated group.
Halo fixation was the preferred method for both Type II and
III fractures. Hard collars were the second most frequently
used device. External fixation was applied for a period ranging
from two to four months depending on fracture characteristics
and surgeon preference. Treatment in a soft collar (n=2) was
reserved for elderly patients whose medical or mental status
would not permit rigid immobilization.
treated with external immobilization were reassessed for fracture
healing with AP and lateral cervical spine radiographs. Forty-five
of 64 acute patients (70%) were available for a minimum three-month
follow-up. Four patients died before fracture healing could
be assessed and fifteen patients were lost to follow-up. The
overall result of external immobilization in acute patients
was a solid union in 34 (76%) and nonunion in 13 patients (24%)
The nonunion rate was substantially higher for Type II fractures
(30%) compared to Type III injuries (17%).
all patients treated with external immobilization, the nonunion
rate observed for posterior subluxation was 38%, for anterior
subluxation 14%, and for nondisplaced fractures 25% (Table
5). The two patients with anterior subluxation and nonunion
had displacements of 3 and 5 mm, well within the range of 3
to 6 mm anterior displacement in their counterparts who fused.
Similarly, in the posteriorly displaced group there was no apparent
correlation between the degree of subluxation and the rate of
nonunion; displacement in six patients with nonunion ranged
from 1 to 8 mm, while displacement in 10 patients who went on
to fusion ranged from 2 to 8 mm. The results of external fixation
were also compared to age (Table
6). Patients in the youngest age group had a much lower
rate of nonunion (17%) compared to the oldest age group (50%).
The middle age groups also demonstrated low to intermediate
nonunion rates increasing with advancing age (11% 35-49 years
and 25% 50-64 years).
the conservatively treated group, a variety of external fixation
devices were used. A comparison of method of external immobilization
with outcome of treatment demonstrates that most patients were
immobilized in a halo vest, achieving a radiographically solid
fusion in 76% (Table
7). Although the numbers are small, 31% of patients (4/13)
treated with a hard collar alone (Plastizote or Aspen collar)
failed to fuse, suggesting halo bracing to be advantageous (24%
nonunion). Only one of six patients treated with a Somi brace
developed nonunion (17%). Two of three patients treated with
a Guilford brace failed to fuse. The two patients treated with
soft collars were lost to follow-up and are not included in
patients in the conservative group (acute and chronic) developed
nonunion following an adequate trial of external immobilization
(28%). Four patients were successfully fused through posterior
cervical approaches (acute Type II n=3, chronic Type III n=1).
One young patient was treated with anterior screw fixation after
failing two weeks of halo immobilization due to loss of reduction.
Four patients were managed with a longer duration of or even
indefinite bracing, and four patients had no further management
stated. It is not known whether patients treated for longer
duration eventually achieved bony union although it is most
likely that a fibrous nonunion was accepted in these elderly
patients underwent operative intervention as the primary form
of treatment for reduction and stabilization of their fractures
(acute n=16, subacute/chronic n=4). In the acute group, 11 patients
with Type II injuries underwent anterior screw fixation, while
four with Type II fractures and one with a Type III fracture
were treated with posterior cervical fusion. In the subacute/chronic
group, two patients with Type II fractures underwent anterior
screw fixation while the other two underwent posterior cervical
fusion. No Type III chronic fractures were initially treated
results of surgical fusion are shown in Table
8. As initial treatment, 13 anterior screw fixation procedures
were carried out, 11 for acute fractures and two for chronic
fractures. Each of five patients with minimum three month follow-up
went on to develop stable fusions (100%). One patient tore out
the odontoid screws 24 hours after placement during an episode
of acute respiratory distress requiring intubation. This patient
was managed with replacement of a single screw on the right
side and instructed to wear a collar at all times when upright.
A solid bony union was confirmed radiographically after three
months. Seven posterior cervical fusions (five for acute and
two for chronic fractures) were performed. Only
one patient was treated with post-operative halo immobilization;
the others were treated with collars. Of the four patients with
adequate follow-up, two acute injuries and one chronic fracture
treated at five weeks achieved stable union. One patient with
a chronic Type II fracture and 10 mm of initial posterior displacement
suffered a loss of reduction following C1-C2 wiring without
neurological deficit. This result was accepted without further
management, leading to a solid arthrodesis. There were two deaths,
both unrelated to surgery.
intervention was not biased towards a younger, potentially healthier
9). Eight surgical procedures were undertaken in patients
under 65 years of age (18%), whereas 12 procedures were performed
in patients 65 years and older (29%). The two postoperative
complications (screw pull-out and loss of reduction) occurred
in the oldest age group.
average hospital stay for patients treated with external immobilization
and an isolated odontoid fracture was 11 days. This compares
with an average hospital stay of 10 days for patients treated
surgically. There was no remarkable difference in length of
stay for patients surgically treated with an anterior approach
compared to a posterior approach.
results observed in this patient cohort support ongoing use
of external immobilization for odontoid fractures with acceptable
rates of bony union. In this series, the incidence of nonunion
in acute odontoid fractures, managed by a variety of fixation
methods, was 24% (11 of 45), or by fracture type was 30% for
Type II and 17% for Type III injuries. These results compare
favorably with the literature; the incidence of nonunion for
Type II fractures ranges from 0-93% averaging 40-50%.[4,6,7]
Greater than an 80% incidence of successful bony union has been
achieved by external fixation methods for Type III odontoid
fractures.[6,8-15] In our series, patients managed with
halo immobilization had a lower nonunion rate (24%) compared
to patients managed with all other external devices (32%). Four
of six failed unions in patients treated in a halo vest were
associated with Type II fractures; a previous review of primary
halo bracing for Type II and Type III fractures demonstrated
a 28% nonunion rate for Type II fractures compared to a 0% nonunion
rate for Type III fractures. In an evaluation of
halo vest versus other rigid external cervical orthoses, Polin
et al found a 100% fusion rate for Type III fractures
regardless of treatment modality. Although the difference was
not statistically significant, halo bracing favored improved
healing over the Philadelphia collar in Type II fractures (74%
versus 53%). Although our patient numbers are also too small
to be certain, use of the halo vest was associated with a trend
towards improved fusion rates compared to collars (76% versus
69%). Within the limitations of a retrospective study, it is
important to note that certain patients, either too frail or
with other contraindications to halo immobilization, may have
been placed in collars, predisposing them to nonunion (selection
authors have found a direct relationship between age versus
morbidity and mortality, and an inverse relationship between
age versus rate of union.[17-20] In this series, all
11 deaths were in patients aged 60 or greater. Five occurred
in the acute setting while six occurred between 10 days and
six weeks post-trauma. Neurological morbidity was distributed
equally between old and young patients; of 12 spinal cord injuries,
six occurred in patients over 65 years of age and the rest in
younger patients. However, medical morbidity (primarily respiratory
complications) was the major factor contributing to death in
elderly patients (only two of 11 were related to the neurological
deficit). Finally, the incidence of nonunion was significantly
higher in the oldest age group (50%) compared with the rest
of the patient population (16%).
issue of fibrous nonunion in elderly patients with odontoid
fractures has been addressed in the literature, with the suggestion
that this may be a sufficient goal of treatment.
In our study, one of eight elderly patients with fibrous nonunion
was treated with posterior cervical fusion without complication;
the remaining seven patients with a range of posterior subluxation
of zero to 8 mm either remained in an external brace or had
no further treatment, often because the surgical risk was deemed
too high. In one to three years of follow-up available, none
met with a catastrophic event.
results also suggest that primary operative intervention for
acute Type II odontoid fractures, through an anterior approach
where possible, may ultimately provide superior rates of bony
union compared with external bracing. In this series, all acute
Type II patients treated with anterior screw fixation (available
for follow-up) went on to solid fusion, compared to eight of
37 acute Type II patients (30%) who failed external bracing
(Table 4). Posterior cervical fusion was similarly successful;
the one case of loss of reduction, although suboptimal, was
healed acceptably without further intervention required. These
results are comparable to other published series in which satisfactory
stabilization has been achieved in 80 to 100% of patients treated
with posterior internal fixation, although rates of only 20%
have also been described (in the absence of transarticular screws
or postoperative halo bracing).[17,22,23] In general,
our results agree with others who suggest that surgical intervention
should be entertained in a more aggressive fashion when other
demographic factors predispose to nonunion, such as patient
age, delay in diagnosis, direction and degree of subluxation,
and complications during external fixation.
procedures in this series of patients were biased to the oldest
age group (28%) compared to the youngest age group (9%). Considering
a nonunion rate in the elderly more than three times that observed
in the younger groups (50% vs. 16%), and the fact that nonunion
occurred exclusively in conservatively treated patients, the
high fusion rates observed in the surgically treated (elderly)
patients argues even more strongly in favor of this as a primary
this retrospective review, halo immobilization for acute Type
II and III odontoid fractures was associated with successful
bone healing in 70% and 83% of patients respectively. A conservative
approach consisting of halo bracing for 12 weeks is a traditional
and effective method for the treatment of odontoid fractures
in most patients, especially those of a younger age group. Halo
fixation likely provides superior fusion rates compared to collar
immobilization. With the introduction of newer surgical techniques,
superior rates of bony union (perhaps approaching 100%) even
in elderly patients appear possible, with little, if any, additional
morbidity. Although it is critical to acknowledge the retrospective
nature of this study, including potential selection bias and
limited follow-up, our results suggest that anterior surgical
fixation may be preferential to external bracing as a primary
treatment for acute Type II odontoid fractures. These observations
lend themselves to further testing through a prospective randomized
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From the University of Calgary Spine Program, and the
Department of Clinical Neurosciences, University of Calgary,
Calgary, Alberta, Canada.
Received January 25, 2000. Accepted in final form June
Reprint requests to: R. John Hurlbert, University of Calgary
Spine Program, Foothills Hospital and Medical Clinic,
1403 - 29th St. N.W., Calgary, AB, T2N 2T9 Canada.
Can. J. Neurol. Sci. 2000; 27: 297-301