Key-words:
Corpectomy - fusion - neck disability index - subaxial cervical spine injuries
Introduction
The cervical spine is injured in 2.4% of blunt trauma injury patients.[[1]] It is more common in elderly, male, and European American ethnicity. The annual
incidence rate is 64/lakhs with two peaks, one in the second and third decade of the
male population and another in elderly females.[[1]] The most common mechanism of injury is noted to be accidental falls followed by
motor vehicle accident. The most common site of injury is the atlantoaxial region,
with the most commonly injured levels in the subaxial cervical spine being C6 and
C7. The C2 vertebra is the most common level of injury (24%) and lower two cervical
vertebrae C6 and C7 constitutes the second-most common level of injury C6 (20.25%)
and C7 (19.08%). C3 is the least likely injured structure, i.e., 4.27%. The subaxial
cervical spine (C3–C7) is particularly vulnerable to traumatic injury due to its considerable
mobility and its proximity to the more rigid thoracic spine.[[1]],[[2]]
The principles in the treatment of unstable cervical spine injuries are reduction
and stabilization of the injured segment, maintenance of cervical lordosis, and decompression
where indicated. Methods of treatment range from nonoperative to combined anterior
and posterior surgical fusion. There is, however, debate on the indications for anterior,
posterior, or combined surgery. The anterior approach is a less traumatic and provides
the ability for decompression, reduction of dislocated facet joints, interbody grafting
with reconstruction and maintenance of lordosis. Although fusion rates are high with
the use of autograft, it is associated with significant graft site morbidity while
the use of allograft, which is devoid of any donor site problems, is associated with
high rates of pseudoarthrosis. To overcome these problems associated with both allograft
and autograft, titanium mesh cages (filled with local bone saved from corpectomy)
are used with advantages of immediate anterior column stability, shorter operation
time, maintenance of intervertebral disc height and lordotic angle, avoidance of morbidity
associated with autologous bone graft (iliac crest) harvesting, good biocompatibility,
and obtain comparable fusion rate to autogenous tricortical iliac bone.[[3]],[[4]]
Although multiple discectomies are an alternative means of decompression in cases
associated with posttraumatic prolapsed intervertebral discs, we preferred corpectomy
to address spinal stenosis caused by age-related degenerative spondylotic changes
(osteophytes), and cervical corpectomy should result in higher fusion rates because
there are only two fusion surfaces.[[5]],[[6]]
In contrast, posterior approaches may be injurious to adjacent levels; this has been
postulated to cause late deformity and with concerns regarding the rate of wound infection,
the inability to address a disrupted disc before reduction.[[7]]
We stabilize the subaxial cervical spine injuries anteriorly with anterior cervical
locking plate and cage filled with bone graft after corpectomy, and the aim of our
study is to directly decompress the cord, to facilitate early ambulation and to evaluate
the clinical improvement, neurological outcome, and radiographic fusion rates.
Materials and Methods
The present study includes prospective patients of subaxial cervical spine injuries
admitted and operated to Indira Gandhi Medical College, Shimla, between February 2014
and February 2016 and these patients were assessed radiologically for fusion using
Bridwell criteria, neurologically using the American Spinal Injury Association (ASIA)
chart, and for functional outcome as per Neck Disability Index and clinical neck movements
pictures were taken. Ethical clearance was taken from the Institutional Ethics Committee
and informed written consent was taken from all the patients.
Inclusion criteria
-
Subaxial Cervical Spine Injury Classification (SLIC) score ≥4
-
Relative sagittal plane translation >3.5 mm
-
Relative sagittal plane rotation >11°
-
Three columns injury and two columns injury with neurological deficit.
Exclusion criteria
-
Patients medically unfit for surgery
-
Patients operated through posterior approach
-
SLIC scores <3
-
Single column injury and two columns injury without neurological deficit.
In our institution, Philadelphia hard cervical collar or cervical traction (either
head halter or Crutchfield tongs) is applied till the fracture is reduced. We excluded
the single level subluxation from our study treated with discectomy and not corpectomy.
Patients with neglected/irreducible subluxation, vertebral body fracture, and multiple
level disc prolapses are included in this study as they needed corpectomy.
On admission of the patient history, clinical examination, routine and specific blood
investigations were done which includes complete hemogram (red blood cell count, hemoglobin,
hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, platelet count,
white blood cell count, and white blood cell differential count) renal function test,
serum electrolytes, fasting blood sugar, electrocardiogram, viral markers for Hepatitis
B, Hepatitis C, HIV I, and HIV II. The radiological examination includes cervical
spine radiograph anteroposterior view, lateral view, and chest radiograph posteroanterior
view. Computerized tomography cervical spine with three-dimensional reconstruction
was done in all patients, and the relevant findings were documented [[Figure 1]]. Intravenous antibiotic (3rd generation cephalosporin) and injection hydrocortisone
1000 mg intravenous are given at the time of induction for general anesthesia. All
patients were given intravenous antibiotics (3rd generation cephalosporin) for 5 days'
postsurgery. All patients were mobilized with Philadelphia collar as soon as possible
by 1st–2nd day. Postoperatively, routine anteroposterior and lateral view of cervical
spine was obtained [[Figure 2]] and [[Figure 3]] to assess the placement of cervical locking plate. The negative suction drain was
removed 2nd postoperative day after the wound inspection. The patient was discharged
on the 5th postoperative day. Sutures were removed on the 14th postoperative day in
the outpatient department.
Figure 1: Preoperative computed tomography scan showing neglected irreducible subluxation C4
over C5 vertebra
Figure 2: Immediate postoperative anteroposterior view after corpectomy C5 vertebra
Figure 3: Immediate postoperative lateral view after corpectomy C5 vertebra
Patients were advised to follow-up after 6 weeks then after postoperative 3 months,
then every 6 months [[Figure 4]] and [[Figure 5]]. Static cervical exercises advised after the surgery. Cervical movements allowed
at 6 weeks. At follow-up, a detailed clinical examination was done, and radiological
assessment was done. Fusion of bone graft was assessed using Birdwell fusion Grade
1. Neck-specific disability was measured as per the Neck Disability Index.
Figure 4: 1.year followup X.ray lateral view showing Birdwell Fusion Grade 1
Figure 5: 1.year follow.up X.ray anteroposterior view showing Birdwell Fusion Grade 1
For statistical analysis, Chi-squared test and t-tests were used, and P < 0.05 was
considered statistically significant.
Results
All cases were followed up for 12–42 months (mean 27 ± 8 months). The mean age was
41.8 ± 15.25 years (range, 15–88 years). The study group consisted of 82 male and
17 female patients. The most common mode of trauma was fall from the height, i.e.,
66.7% followed by roadside accident 33.3%. Of 99 patients, preoperatively, three patients
had ASIA B neurology, 21 patients had ASIA C neurology, 41 had ASIA D neurology, 34
patients had ASIA E neurology, and postoperatively, one patient had ASIA B neurology,
four patients had ASIA C neurology, 36 patients had ASIA D neurology, and 58 patients
had ASIA E neurology. No patient showed any deterioration of the neurological symptoms
after surgery [[Table 1]]. The study group consisted of majority of 43 patients with vertebral body fracture,
11 patients with fracture dislocation, nine patients with pure subluxation, and remaining
36 were categorized into posttraumatic disc prolapsed without significant vertebral
body injury. According to AO (Arbeitsgemeinschaft für Osteosynthesefragen) classification,
60.6% were type B, 33.3% were type C and 6.1% were type A.
Table 1: Neurological charting preoperative and postoperative
The most common level of vertebral fracture was C5 in 21 (21.2%) followed by C6 in
14 (14.1%). Of the 99 procedures, 77 (77.8%) involved a single vertebral level, 19
(19.2%) involved two levels, 3 (3%) involved three levels corpectomy, and most common
vertebra to be corpectomized was C5 in 28 (28.3%) followed by C6 in 22 (22.2%). The
incidence of neurological deficit was more in patients in which two or three vertebra
corpectomy was done (20 out of 22, i.e., 90.90%) compared with patients, in which
single-level corpectomy was done (47 out of 77, i.e., 61.03%) and it is significant
(P = 0.029) [[Table 2]]. In our study, 22 (22.22%) patients had multiple level corpectomy and of that 17
(17.17%) patients were in age group >45 years and is statistically significant (P
= 0.006) [[Table 3]].
Table 2: Number of corpectomy vertebra versus neurological deficit
Table 3: Number of corpectomy vertebra and age groups
Functional outcome was assessed using Neck Disability Index. About 62.6% of patients
had mild disability and 27.3% had no disability, 6.1% had moderate disability and
4.0% had severe disability according to the Neck Disability Index. Mean Neck Disability
Index is 7.57 ± 5.42.
Fusion was assessed using the Bridwell criteria.[[8]] Of the 99 patients, 64 (64.6%) patients showed Grade 1 fusion, 31 (31.3%) patients
showed Grade 2 fusion, and 4 (4.0%) patients showed Grade 3 fusion.
Of 99 patients, 79 (79.8%) patients had postoperative transient dysphagia which gradually
resolved in all patients and only one patient has minimal screw back out.
Discussion
The subaxial cervical spine is having considerable mobility and proximity to the more
rigid thoracic region, hence prone to traumatic disruption. Many surgical series recommend
early treatment with aggressive canal decompression, improving neurological outcomes
and also offering immediate stabilization.[[9]],[[10]],[[11]],[[12]],[[13]] In subaxial cervical spine injuries, SLIC score is used to determine the threshold
for surgical intervention. In our study, for these patients with SLIC score 4 preferentially
early surgery was indicated in view of:
Refinements of spinal instrumentation and early mobilizationMost of the patients in
our study with SLIC score 4 were in young age group (55% in 15–30 years and 80% in
15–45 years)Severe radiculopathy involving motor and sensory impairmentRadiological
parameters associated with failure in conservative management of these injuries, such
as ≥40% of height compression, kyphotic angulation higher than 15° or 20% of subluxation
of one vertebra on another are not addressed by the SLIC score.[[14]],[[15]]
Surgical stabilization has been described using both anterior and posterior approach
or combined approach.[[8]],[[16]] In our study, subaxial cervical spine injuries treated operatively with anterior
corpectomy and stabilization with cage filled with autologous bone graft of vertebral
body and cervical locking plates are studied. The advantages of using interbody cages
for reconstruction after anterior cervical corpectomy fusion include, avoidance of
morbidity associated with autologous bone graft (iliac crest) harvesting, compared
with multilevel anterior cervical discectomy and fusion should result in lesser fusion
rates because of increased graft-host interfaces where fusion needs to occur.[[17]]
The purpose of this prospective cohort study was to analyze the clinical and radiographic
results of cages in the surgical treatment of patients with traumatic cervical spine
instability.
Most of the patients with Grade 1 fusion have no disability (P = 0.021). This comparison
is significant. Most patients with Grade 1 fusion had less incidence of neurological
deficit (P = 0.043) and is significant. Most of the patients with Grade 1 fusion had
ASIA E neurology (P = 0.001) and is highly significant.
The Neck Disability Index score used in this study was highly correlated with the
neurological outcome in the form of ASIA score, and the radiological outcome in the
form of Bridwell fusion criteria.
The incidence of neurological deficit was more in patients which required multiple
level corpectomies, and most of the patients which required multiple level corpectomies
were in elder age groups.
Of 99 patients, 79 (79.8%) patients had postoperative transient dysphagia which gradually
resolved in all patients.
Only one patient had minimal screw back out and is without any deficit and is currently
under the sequential follow-up.
Conclusions
Anterior cervical corpectomy and stabilization with cage filled with bone and cervical
reflex locking plate is good and safe method in treating subaxial cervical spine injuries.
This procedure has benefits of high primary stability, anatomical reduction, and direct
decompression of spinal cord with minimal complications.
