Open Journal of Orthopedics, 2013, 3, 296-299
Published Online November 2013 (http://www.scirp.org/journal/ojo)
Open Access OJO
Evaluation of Conservative Treatment of Acute Fracture of
the Odontoid Process of Axis with a Halo-Vest*
Yuichiro Yokoyama, Hiroshi Takahashi#, Yasuaki Iida, Yasuhiro Inoue, Keiji Hasegawa,
Daisuke Suzuki, Shintaro Tsuge, Wataru Shishikura, Katsunori Fukutake, Ryo Takamatsu,
Kazumasa Na kamura, Akihito Wada
Department of Orthopaedic Surgery, Toho University School of Medicine, Tokyo, Japan.
Received September 13th, 2013; revised October 25th, 2013; accepted October 5th, 2013
Copyright © 2013 Yuichiro Yokoyama et al. This is an open access article distributed under the Creative Commons Attribution Li-
cense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
We fitted a halo-vest on patients with a fracture of the odontoid process of the axis and evaluated the effects of conser-
vative treatment on cervical muscular atrophy and the number and type of patient complaints after bone union. Four
patients had Anderson Type II fractures and 6 patients had Type III fractures. Bone union was observed in all patients
within 3 months after injury. After halo-vest fitting, cervical muscular atrophy increased with time, however, it gradu-
ally improved after removal of the halo-vest. Patients fixed with a halo-vest for more than 10 weeks complained of cer-
vical discomfort and limited range of motion. No patients with fixation for less than 10 weeks had problems in bone
union or had cervical complaints. Thus, less than a 10-week fixation period was considered to be appropriate.
Keywords: Fracture; Odontoid Process of the Axis; Halo-Vest; Conservative Treatment
Surgery is recommended for patients with a fresh frac-
ture of the odontoid process of the axis because it allows
for early discharge and successful rehabilitation. How-
ever, the only option is the conservative therapy if a pa-
tient has poor systemic conditions or does not desire sur-
We examined the appropriate fixation period based on
the percentage of bone union and complaints after re-
moval of the halo-vest. We also evaluated the degree of
atrophy of the posterior cervical muscle that underwent
conservative therapy using a halo-vest.
2. Materials and Method
The subjects included 10 patients (6 males and 4 females)
aged from 17 to 82 years (mean: 47 yrs) with a fresh
fracture of the odontoid process of the axis who under-
went conservative therapy using a halo-vest in our hos-
pital between June 2004 and January 2013.
The causes of injury were falling down the stairs (5
patients), traffic accident (3 patients), rugby accident (1
patient), and suicide attempt (1 patient).
The follow-up period was from 7 months to 4 years
and 1 month (mean: 1 year and 5 months).
Patients were classified into Anderson Type II  (4
patients) and Type III (6 patients). Eight of them had no
impaired consciousness or neurological deficits at the
initial visit, however, the remaining two were intubated
and we could not confirm if they had any impairment
The area of muscular atrophy was determined by di-
viding the CT cross-sections of the sternocleidomastoid
and posterior cervical muscles at C5/6 level into seg-
ments a, b, c, and d using the RapideyeTM (Toshiba
Medical Systems Corporation, Japan). The degree of
muscular atrophy was measured over time, and we set
the degree at the time of injury as 100% (Figure 1).
The fixation period of halo-vest ranged from 6 to 11
weeks (mean: 8 weeks). Bone union was confirmed in all
patients within 3 months after injury, however, 2 patients
with fixation for more than 10 weeks still had cervical
*Conflict of interest: None
Financial support: None
Evaluation of Conservative Treatment of Acute Fracture of the Odontoid Process of Axis with a Halo-Vest 297
Table 1. Patient characteristics .
Case Age Fracture type Neurological deficitsComplicationFixation period(w)Cervical complaints ROM limitation
1 82 Anderson II • Head injury 10 + -
2 20 • II unknown Brain injury 7 - -
3 49 • II unknown Levine TypeⅠ8.5 - -
4 55 • II • • 8 - -
5 72 • III • Head injury 7 - -
6 75 • III • Brain injury 8 - -
7 26 • III • • 11 + -
8 49 • III • • 7 - -
9 17 • III • Levine TypeⅠ8 - -
10 25 • III • • 6 - -
Figure 1. Method for measuring muscular atrophy. Method
for measuring muscular atrophy: the area of the sterno-
cleidomastoid and posterior cervical muscle at C5/6 level is
measured by CT.
complaints at the final examination (Table 1).
The degree of muscular atrophy was 95.2% - 99.2%
(mean: 98.0%) 12 months after injury (Table 2).
In 8 patients with less than a 10-week fixation period,
the mean degree of muscular atrophy 12 months after
injury was 98.7%, and there were no cervical complaints.
In contrast, in 2 patients with a fixation period of 10-
weeks the mean degree of muscular atrophy was 95.8%
and the complaints included cervical pain, stiff neck, and
cervical discomfort (Table 3).
Muscular atrophy progressed in all subjects after
halo-vest fitting, however, it improved immediately after
removal of the halo-vest.
Table 2. Changes in degree of muscular atrophy.
Case at the time
of injury 1 2 3 6 12(M)
1 100 90.1 83 79.3 94 96.4
2 100 91.1 83.2 80.3 96.2 98.9
3 100 89.9 81.5 86.5 97.2 99.2
4 100 89.2 82 86.7 97 99
5 100 88.1 79.2 87.6 93.4 98.2
6 100 89.2 83 86 97 99
7 100 90.6 83.6 78.7 94.3 95.2
8 100 89.5 82.9 87.1 95.5 99
9 100 92.1 83.7 79.1 96.8 97.8
10 100 89.7 81.9 85.3 95.1
mean100 89.9 82.4 83.6 95.6 98.0%
Table 3. Relationship between duration of the fixation pe-
riod and muscular atrophy.
Duration of fixation
period Degree of muscular atrophy
6 and < 10weeks
(n = 8)
1 month after injury
12 month after injury
(n = 2) 90.3% ~ 95.8%
(n = 10) 89.9% ~ 98.0%
4. Case Report
Case 5: a 72 year-old female who was injured from a fall
down the stairs. She was transported by ambulance due
to a chief complaint of cervical pain but did not have
marked neurological deficits. The radiograph findings at
the first medical examination showed an Anderson Type
III fracture of the odontoid process of the axis. The pa-
tient was fixed with halo-vest for 7 weeks and bone un-
Open Access OJO
Evaluation of Conservative Treatment of Acute Fracture of the Odontoid Process of Axis with a Halo-Vest
ion was confirmed at 12 weeks by radiograph. The de-
gree of muscular atrophy 12 months after injury was
98.2%. She had no cervical pain and had full range of
motion at the final examination (Figure 2).
Figure 2. A 72-year-old female who was injured from a fall down the stairs. The radiograph findings at the first medical ex-
amination showed an Anderson Ty pe III frac ture of the odontoid pr ocess of the axis. Bone union w as confirme d at 12 months
after injury. She had no cervical pain and had full range of motion at the final examination. a Lateral cervical radiograph at
the first visit; b CT findings at the time of the first visit; c Lateral cervical radiograph at 12 moths after injury; d CT findings
at 12 months after injury.
Open Access OJO
Evaluation of Conservative Treatment of Acute Fracture of the Odontoid Process of Axis with a Halo-Vest 299
Surgical therapy is recommended for patients with a
fresh fracture of the odontoid process of the axis because
it allows for early discharge and successful rehabilitation.
However, surgery cannot always be conducted. If a pa-
tient has poor systemic conditions or does not desire sur-
gical therapy, and if there are problems with access to the
appropriate equipment, the only option is conservative
therapy. Therefore, the percentage of bone union in con-
servative therapy was evaluated in patients treated in our
hospital. The mean percentage of bone union of halo-
vest-fixed odontoid process fractures was 72.6% in
Anderson Type II patients [1,3-7]. Greene et al. 
showed that the percentage of bone union in 340 Ander-
son Type II patients treated with conservative therapy
was 79%. They also found that the percentage of bone
union of patients with a ≥6 mm fracture dislocation at the
time of injury was significantly different, consequently,
injury to the soft tissues was affected it. It was confirmed
that the percentage of bone union in Type III patients
was better than that of Type II patients [1,3,4,5,7] and the
mean percentage of bone union was 97.5% [1,3,4,5,7]
(Table 4). Therefore, an Anderson Type II patient with
≥6 mm fracture dislocation was considered to be a can-
didate for surgery in our hospital based on the results of
Greene et al. . Patients in this study were Anderson
Type II with <6 mm and III fracture dislocations who
could not undergo surgery due to multiple trauma or did
not desire surgery. Bone union was observed in all of our
patients at 3 months after injury.
Muscular atrophy in the sternocleidomastoid and pos-
terior cervical muscles was evaluated based on the dura-
tion of the fixation period. Callus formation in radio-
graph and CT findings was detectable, however, it was
difficult to evaluate when the halo-vest was removed.
The longer the fixation is, the better the bone union ad-
vances. However, muscular atrophy occurs, possibly re-
sulting in cervical pain, stiff neck, cervical discomfort, or
limited range of motion in the cervical spine. Therefore,
muscular atrophy was measured over time. Ono et al. 
examined cervical muscular atrophy after halo-vest fit-
ting and showed that atrophy was observed in approxi-
mately 15% of the sternocleidomastoid muscles and in
22% of the posterior cervical muscles, and cervical dis-
comfort and limited range of motion were found when
atrophy was observed in more than 20% of the posterior
cervical muscles. Atrophy in the sternocleidomastoid and
posterior cervical muscles in this study was less than that
in Ono’s study because no patients were fixed with a
halo-vest for as long as 3 months. However, complaints,
including stiff neck and cervical discomfort in patients
with fixation for 10 weeks or more, were more frequent
than those in patients with cervical muscular atrophy for
less than 10 weeks.
Table 4. Bone union rates.
Fracture type Bone union
rates No. of cases
fracture Anderson Type II 72.6% 386/531 cases
Type III 97.5 241/247
Based on these results, no patient with fixation for less
than 10 weeks had problems with bone union. Thus,
fixation with a halo-vest for less than 10 weeks is appro-
priate for a fresh fracture of the odontoid process of the
axis since cervical muscular atrophy and complaints as-
sociated with muscular atrophy are caused by long-term
Halo-vest is useful for treatment of a fresh fracture of the
odontoid process in patients who cannot have surgery,
and the appropriate fixation period should be less than 10
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