Surgery result assessment of C1 lateral mass and C2 pedicle screw fixation in treating unstable C2 odontoid/dens fracture in Phu Tho general hospital

JOURNAL OF MEDICAL RESEARCH

SURGERY RESULT ASSESSMENT OF C1 LATERAL MASS AND
C2 PEDICLE SCREW FIXATION IN TREATING UNSTABLE C2
ODONTOID/ DENS FRACTURE IN PHU THO GENERAL HOSPITAL
Son Nguyen Van1, Toan Do Thi Thanh2, Ngoc Nguyen Huy1, Hoat Luu Ngoc2
1

Phu Tho General Hospital, Vietnam; 2Hanoi Medical University, Vietnam

Superior cervical spinal lesions account for 25% of cervical spinal lesion. Due to the special structure of
superior cervical spine and the diversity of anatomical lesions, various non-surgical treatment methods such
as Mini Verve powder, Halo frame, continuous traction, as well as surgical methods such as occipital splints,
screwing through joints, C1 - C2 posterior arch binding, screwing through the odontoid process...have been
applied to treat these lesions.Comparing these techniques, the fixation of the C1 lateral mass and C2
pedicle with polyaxial screws has many advantages and has been widely applied in recent years. The aim of
this study was to assess the result of Atlantal lateral mass and axis pedicle screw fixation for the treatment of
unstable C2 odontoid fracture. We investigated the clinia records of 20 patients suffered from unstable C2
odontoid fracture whom received an Atlantal lateral mass and axis pedicle screw fixation at Phu Tho General
hospital from 1/2012 to 12/2015. Of all the patients, no intraoperative complications were observed. The average recovery time was 15 days, as being judged by clinical systems after surgery without major neurological complications and wound infection. We concluded that the C1 lateral mass and C2 pedicle screw fixation
for treatment of unstable odontoid fracture is a suitable option for these conditions with a high success rate
and few complications.
Keywords: C1 lateral mass, C2 pedicle screw fixation, unstable C2 odontoid/dens fracture

I. INTRODUCTION
line, solidifying the vertebrae and maintaining
C2 Odontoid fractures account for 10 -

C1 - C2 rotational movement. The bone weld-

20% of cervical spine fractures. However, only

ing rate with this technique is approximately

type II unstable odontoid fractures, or included

90%. However, this technique is difficult to

with C1 - C2 dislocation, are candidates for

perform when the fractured odontoid is com-

surgery [1 - 3]. These surgeries would solidify

bined with C1 - C2 dislocation [3].

the vertebrae and decompress it if needed.
There are multiple treatment methods for C2
odontoid fracture and two main types of treatments are anterior fusion and posterior fusion:

Posterior fusion to achieve stable fixation
of C1 - C2 junction consists of multiple different methods such as Magerl’s screw interarticulation C1 - C2 surgery with a relatively

Anterior fusion by screw inter-articulation

high bone welding rate of 78 - 99%. However,

odontoid was first performed by Bohler. This

the risk of damage to the vertebral artery is

technique involves directly fixing the fractured

high and this method is difficult to perform to
severe C1 - C2 dislocation in patients with a

Corresponding author: Do Thi Thanh Toan, Ha Noi
Medical University
Email:
Received: 15/7/2018
Accepted: 18/11/2018

JMR 116 E3 (7) - 2018

thoracic kyphosis (Hunchbacked) [4; 5]. In
2001, Harms and Melcher disseminated the
technique of C1 lateral mass and C2 pedicle
screw fixation. Harms’ C1 - C2 fixation method

53


JOURNAL OF MEDICAL RESEARCH
is a suitable option with low risk, easily mend-

vertebrae, classification of the spinal damage,

able C1 - C2 and high bone welding rate [6].

determination of the anatomical structure of

We studied and applied the posterior C1

the vertebrae and C1 lateral mass and meas-

lateral mass and C2 pedicle screw fixation for

urement the size of C2 stem and to have a

treating unstable C2 odontoid fracture and

post-op precision of the position and location

dislocated C1 - C2 in order to evaluate the

of screw insertion by 64 rows of computed

result as well as the advantages and disad-

tomography with perioperative vertebral artery

vantages of this method.

rendering.

II. METHODS
1. Subjects
Patients who suffered from unstable C2
odontoid fracture and received a atlantal lateral mass and axis pedicle screw fixation at
Phu Tho General Hospital in 3 years, from
01/2012 to 12/2015.

+ Assessment of the spinal cord, soft tissue
and to determine patient prognosis through
MRI.
Operative technique
The patients received tracheal intubation in
the prone position and their heads were fixed
on May-Few frame. The incision was made
along to the ligamentum flavum, in the bottom

Inclusion criteria

of the occipital C5, C6. The lower bone mem-

+ Suffered from unstable C2 odontoid frac-

brane of muscle mass next to spondylosis was

ture.
+ Were operated in atlantal lateral mass
and axis pedicle screw fixation.

then incised to the outer edge of C2 - C3 joint.
The lower bone membrane above the C1 posterior arch was then exposed to enable the
visualization of the C1 lateral mass and to al-

2. Methods

low for the inner side of the C1 lateral mass.

- Study design: A case series study .

The vertebral artery runs along artery channel

- Time: from 1/2012 to 12/2015.

above C1 posterior arch, and the C2 nerve

- Place: Phu Tho General hospital.
- Sample size and Sampling: Total sampling during the study period is 20 patients met
criteria. They were all included in the study.

root usually lies from lateral mass to the C1
posterior arch. After protecting vertebral artery
and C2 root by high-speed grinding with 3mm
drill bit into the center of C1 lateral mass, aim
the screw a 10 - 15 degrees to the center ac-

- Variables

cording to horizontal plane. The screw fixa-

+ Perioperative clinical symptoms.

tions into the C1 lateral mass are 26 – 34 mm

+ Assessment of nerve damage according
to ASIA scale.

long and 3.5 mm in diameter was then performed. The guiding mark to place the screw

on the C2 stem was one third the length in the

+ Assessment and classification of C1 - C2

center of C2 joint block. The screw was then

damage through conventional X-ray imaging

directed to the inner, upper edge of C2 arch,

(straight, lateral, open- mouth).

and thereafter was aimed 15 -20 degrees to

+ Assessment of the condition of the
54

center and upwards 20 degrees. The fixation
JMR 116 E3 (7) - 2018


JOURNAL OF MEDICAL RESEARCH
rod for the C1 - C2 was then placed. The outer

to refuse answering questions that they did not

section of the C1 and C2 posterior arches

want to answer and stop at anytime they

were then grinded and grafted by part of the

wanted.

C3 spondylosis. Muscles are then grafted into

III. RESULTS

the spondylosis behind the C2. Closure of the
skin by sutures.

The average age of patients was 35.2
years old; the youngest patient was 15 years

3. Research ethics

old while the oldest was 75 years old. There
The research protocol was conformed to

were 18 male and 2 female patients who par-

the Helsinki Declaration and all the interviews

ticipated in the study.

have been conducted with the consent form

The primary causes for fractured odontoid

sent to the study subjects or to their parents if

were traffic accidents and falls. Among 20

they were under 17 years old at the point of

study patients, traffic accidents accounted for

being interviewed. Respondents had the right

8 and falls accounted for 12.

Table 1. Clinical signs
Clinical signs

Cases number

Ratio %

High neck pain

18

90%

Sensory disorder

10

50%

Circular muscle disorder

2

10%

Quadriplegia

1

5%

According to the Anderson and D’Alonzo classification, all 20 study participants had type 2
odontoid fracture. Result from Table 1 shows that 18 patients (90%) had neck pain, 10 patients
(50%) reported numbness on both hands and 2 (10%) patients had post-traumatic circular muscle
disorder. There was only 1 patient who has quadriplegia, MRI showed spinal stenosis corresponding to the injury but no obtrusion to the artery.
The C1 lateral mass and the C2 pedicle screw fixation had been, as indicated by comparing
pre- and postoperative images, successfully performed in all patients. There were no cases of
vertebral artery injury or other complications during operation. Mending was performed relatively
easily. Two patients with sensory disorder and circular muscle disorder were required to decompress C1 posterior arc, MRI revealed compressed muscles caused by dislocated C1 - C2. After
the surgery, 18 patients had reported fewer bouts of neck pain as well as hand numbness. Ninety
percent of them report no circular muscle disorder post-operation. One patient who had quadriplegia due to compressed C2 - C3 spinal cord are able to walk again after 1 year undergoing surgery
but have not completely recovered with numbness in both hands still occurred.

JMR 116 E3 (7) - 2018

55


JOURNAL OF MEDICAL RESEARCH

Pre-surgery images

a. Odotoid/

dens

Post surgery images

fracture pre-surgery

images

b. Post surgery images of C1 lateral mass
screw fixation

c. Images of vertebral arteries

e. Images of posterior C2 spinous process

d. Image of post C1 and C2 screw fixation

f. Post screw fixation image of C1 and C2

fracture
Figure 1. Pre and post surgery images

56

JMR 116 E3 (7) - 2018

JOURNAL OF MEDICAL RESEARCH
Case illustration

Placing the screw on the inner upper edge

A 33-year-old male patient was the victim

of the C2 pedicle, direct toward the center at

of a road accident with his head and neck

an angle of 20 degrees and upward of 20 de-

bump against the road. After falling, he

grees. Set fixed rod to join C1 - C2. The corti-

remained conscious but with severe neck

cal bone in the outermost of arcs C1 and C2

pain, exacerbated by movement. With neck

was crusted and transplanted by bone of C3

movement restrained, CT scan of the neck

posterior spinosity. The tendon was stitched

spine showed C2 odontoid process fracture

into C2 posterior spinosity. Close the skin ac-

type II.

cording to the anatomical layers.

The patient was scanned by 64-slide CT

Postoperative patient was given antibiotics,

scanner to determine the anatomical structure

, then could sit up and exercise early, thread

of the C1 - C2 vertebral body, the C1 lateral

cut and discharged from the hospital 15 days

mass, examine the size of the pedicle of C2,

after the surgery.

and the vertebral artery location when passing
C2 and C1.

IV. DISCUSSION

Surgerical Technique: Endotracheal anes-

Surgical treatment for C2 odontoid process

thesia with the posture of lying in the prone

fracture has many different methods. In gen-

position. The head was fixed on May-Few

eral, there are two main types of surgery: fron-

frame. Incision of skin was along the posterior

tal way surgery and posterior way surgery

interspinous line from the point under the outer

Frontal way surgery by screwing through the

occiput to the C5, C6 spinous process. Dis-

odontoid apophysis was first performed by

section of the muscle mass beside the bilat-

Bohler [7; 8]. This technique directly fixes the

eral spinal spinosity under the periosteum to

fracture, strengthens the spine of the neck,

the outer edge of joint C2 - C3. Dissection be-

preserves the rotation of C1C2. Bone weld

neath the periosteum, above C1 posterior arch

rate is about 90%. But this technique is difficult

to both sides to see the C1 lateral mass. The

to perform when odontoid process fractures

inner edge of C1 lateral mass was palpable.

involve severe C1C2 dislocations.

The vertebral artery was in the artery groove

Posterior way surgery to harden C1C2 also

above the C1 posterior arch. Normally, C2

has many different methods such as lateral

radicle is located from lateral mass to the C1

mass screwing surgery C1 and the C2 pedicle

posterior arch. After protecting the vertebral

that has many advantages. In 2002, Author

artery and C2 radicle, high-speed grinding

Goel reported 160 cases that were operated

drills with a 3-mm bit were used in the middle

with splint screw at C1 lateral mass and C2

of C1 lateral mass to screw toward the center

pedicle; no patient then had neurological and

crossing horizontal plane made the angle of

vascular complications [9]. In 2001, Harms

10 degrees. After Taro set screw 34mm long,

and Melcher reported 37 cases of screwing C1

diameter 3.5 mm into the C1 lateral mass. The

lateral mass and C2 pedicle that also resulted

point to place the screw through the C2 pedi-

in 100% bone and no vascular and neurologic

cle was in the middle of the upper one third of

complication [6]. In 2010, Mummaneni studied

the C2 pedicle.

42 cases of C1 lateral mass screwing showing

JMR 116 E3 (7) - 2018

57


JOURNAL OF MEDICAL RESEARCH
high bone weld rate, reduced neck pain and

pedicle, because if the C2 pedicle were too

improved neurological function [4].

small, this technique could not be applied.

Regarding to determining the bolt point on

During surgery, continuously use C-Arm 3D to

C1 lateral mass, there are many different

well control the path of the screw to reduce the

views: The authors Harms and Goel screwed

risk of injury to vertebral artery and spinal

directly to the mass under posterior arch C1

cord.

after rolling up the C2 radicle downward [1].
Tan, Wang and associates screwed on C1 to
the lateral mass for good results. In this case,
we screwed directly on C1 posterior arch and
found many advantages: there is no need to
roll up C2 radicle, the screw was quite firm
because the part of screw in the bone was
long,

which

was

favorable

for

C1C2

dislocation treatment. However, the bolt point
was just on the posterior arch, near the

vertebral artery groove, thus, vertebral artery
is vulnerable [10]. Therefore, according to us,

Figure 2. Vertebral arterial abnormality

understanding of the path of the vertebral

image

artery before the surgery by using 64-slide
construction scan would help to avoid this
complication.
Through

V. CONLUSION
Screwing surgery through C1 lateral mass

the

study,

we

found

that

and C2 pedicle should be applied to patient

preoperative screening was of paramount

with sprained C1C2, odontoid process fracture

importance. Patients are required to have a 64
-slide construction scan to determine the
anatomy of the path of lateral vertebral artery
because, according to the literature, 15 to 20%
of patients have abnormalities of anatomical
vertebral artery. We met a case of odontoid
process fracture type II, 64-slide construction
scan showed abnormality of the path of left
vertebral artery that went over the posterior
anterior facet of C1 lateral mass. In that case,
we had to use the surgical method of screwing
through the C1C2 joint and the patient also
had surgery successfully.

fix but keeping ability to exercise cervical
spine after surgery and it’s safe. However, it is
needed to carry out preoperative examination
thoroughly together with modern medical
equipment, and it needs high accuracy and
surgeon’s experiences.

ACKNOWLEDGEMENTS
We highly appreciate the Phu Tho provincial general hospital for providing the data,
allowing and supporting us to perform our research. We would like to thank Department of

Vertebral arterial abnormality image

Biostatistic and Health Informatic, Hanoi Medi-

It is important to take 64-slide scan to have

cal University for technical assistance and ed-

anatomical determination of the size of the C2
58

type II as it results in high bone weld rate, firm

iting the manuscript.
JMR 116 E3 (7) - 2018


JOURNAL OF MEDICAL RESEARCH

REFERENCES
1. Aryan HE., Newman CB., Acosta FL
(2008). Stabilization of the atlantoaxial complex via C1 lateral mass and C2 pedicle screw
fixation in multicenter clinical experience in
102 patients: modification of the Harms and
Goel technique. J Neurosurg Spine, 8, 222 229.
2. Fessler RG., Sekhar L (2006). Posterior

6. Harms J., Melcher RP (2011). Posterior
C1-C2 fusion with polyaxial screw and rod
fixation. Spine, 26, 246 - 247.
7. Nguyen Van Thach., Nguyen Le Bao
Tien., Dinh Ngoc Son et al (2013). Evaluation of initial results of C1 lateral mass and C2

pecicle screw fixation in treating post trauma
unstable high cervical spine. Vietnamese
Journal of Trauma and Orthopedic, 12 - 19.

atlantoaxial fusion: Surgical Anatomy and

8. Borne GM., Bedou GL., Pinaudeau M

Technique option. Atlas of neurosurgical tech-

(1984). Treatment of pedicular fractures of the

niques, 128 - 139.

axis. J Neurosurg, 60, 88 - 93.

3. Ryken TC., Hadley MN., Walter BC

9. Goel A., Desai KI., Muzumdar DP

(2013). Management of isolated fractures of

(2002). Atlantoaxial fixation using plate and

the axis in adults. Neurosurgery, 72, 132 - 150.

screw method: A report of 160 treated

4. Mummaneni PV., Lu DC (2010). C1
lateral mass fixation: A comparison of constructs. Neurosurgery, 66, A68 - A82.

5. Pryputniewicz DM., Hadley MN (2010).
Axis fractures. Neurosurgegy, 66, A68 - A82.

JMR 116 E3 (7) - 2018

patients. Neurosurgery, 51, 1351 - 1357.
10. Tan M., Wang H., Wang Y (2003).
Morphometric evaluation of screw fixation in
atlas via posterior arch and lateral mass.
Spine, 28, 888 - 895.

59