To compare the radiological and clinical outcomes of
cages with the conventional autogenous iliac crest graft in
anterior cervical discectomy and interbody fusion for single
level cervical disc disease.
and Methods: A
total of 48 patients with single level cervical discogenic
radiculopathy were randomly divided into two groups. Patients in
Group A (24 patients) underwent anterior cervical discectomy and
fusion with a cage filled with autogenous iliac cancellous
bone), and patients in Group B (24 patients) were treated with
discectomy and autogenous iliac crest graft (AICG) fusion. There
were 30 men and 18 women with a mean age of 41.2 years (range,
25–62). We evaluated the patients for cervical lordosis, the
amount of interspace collapse and fusion status on the basis of
x-rays, the patient’s neurological and functional outcomes
were assessed on the basis of Odom’s criteria,
The two groups had similar clinical results and fusion
rates. However, the loss of cervical lordosis (2.5º) was less
in the cage group than in the autograft group (5.25º).
Additionally, the anterior interspace collapse (1.53 mm) in the
cage group was less than the collapse recorded in the autograft
group (2.72 mm). The operative time, the blood loss and
hospitalization time was less in the cage group.
Our results showed that the cage is superior to the
autograft in maintaining cervical interspace height and cervical
lordosis after one-level anterior cervical decompression
procedure with reduction of the operative time and no bone graft
donor site complications.
radiculopathy;cervical cage; autogenous iliac crest graft
Since Cloward’s (1958)1 and Smith and Robinson’s
innovations in anterior approaches to the cervical spine, a
variety of surgical techniques have evolved for the treatment of
cervical disc herniation and spondylosis causing radiculopathy
and myelopathy. Anterior cervical discectomy and interbody iliac
autograft fusion procedures (ACDF) have become widely accepted
for these conditions.
Anterior interbody fusion is intended to provide immediate
biomechanical support, restore physiologic disc height, maintain
cervical lordosis, and achieve fusion. Bone autograft has the
advantages of not requiring the implantation of foreign bodies
and achieving complete bony fusion. However, various
complications have been reported for bone autografts, including
graft collapse, graft dislodgment, pseudarthrosis and cervical
kyphosis3,4. Donor-site complications also have been reported,
including. Haematoma, abdominal hernia, lateral cutaneous nerve
injury, infection, fracture and chronic pain 5-7.
Donor site morbidity has stimulated the search for non autologus
materials as alternatives for cervical interbody fusion. Many
bone graft substitutes have been investigated, but none have
been conclusively proven superior to autologous bone in cervical
fusion8. Since 1999, Interbody fusion cages has been widely used
for the treatment of degenerative cervical spine disease9. It
has been reported that the interbody cage fusion prevent disc
space collapse, maintain cervical lordosis and avoid donor-site
morbidity10,11. Complications, however, have been reported,
including subsidence of cages into the adjacent vertebrae, with
collapse of the intervertebral space and kyphotic deformation of
the affected segment, cage dislocation, and non-union with
The most effective bone graft fusion substrate currently is
uncertain. Therefore, we compared the differences among the two
most commonly used options; autologous iliac crest grafts; and
cages. We attempted to clarify which fusion approach is the best
for one-level anterior cervical interbody fusion procedures. We
wanted to find out which fusion substrate creates the best
clinical result, which achieves the highest fusion rate, which
achieves the quickest fusion, which has the best maintenance of
the interbody space (including interspace height and segmental
lordosis), and which has the least complications. Radiographic
and clinical results of surgical treatment of patients with
discogenic radiculopathy were collected.
prospective study was conducted by an orthopaedic spine surgeon
in Mansoura university hospital from January 2004 to May 2006.
We analyzed the clinical outcomes of patients who underwent
treatment with interbody cage (Group A, 24 patients) and
patients who were treated with AICG fusion (Group B, 24
patients). In Group A, we enrolled 14 men and 10 women (age
range, 25–60 yr; mean age, 42.2 yr); in Group B, we enrolled
16 men and 8 women (age range, 28–62 yr; mean age, 39.8 yr).
The demographic data and levels of discectomy are shown in Table
clinical symptoms included intractable radiculopathy, caused by
nerve root compression. Surgery was done when the patient had
radiculopathy with severe or progressive neurologic deficit
(weakness or numbness), or failure of conservative treatment (a
minimum of 3 months). The findings of magnetic resonance imaging
(MRI) and the clinical level of neurologic deficit were
correlated to determine the level of surgery. Only patients
requiring one level surgery at levels between C3 and C7 were
considered eligible for this study. Exclusion Criteria
included myelopathy, diagnosis of cervical fracture or
posttraumatic instability, previous surgery at the same
vertebral level (Table 2).
the clinical findings included neck pain with pain radiating to
the right arm (22 patients), pain radiating to the left arm (15
patients), pain radiating to both arms (5 patients), neck pain
without radiating pain (4 patients) and motor weakness (2
patients were randomly allocated between either fusion with cage
or with a tricortical graft harvested from the iliac crest. The
method of randomisation was based upon the order of the patient
in the series. For odd numbers, the patient underwent a cage
fusion and for even numbers, a tricortical graft was used.
A underwent anterior discectomy with PEEK (polyetheretherketone)
cage. We drilled out a core of cancellous bone for grafting
using a T-shaped cannulated driver through the iliac crest. The
wound was about 1 cm in length and 2 cm in depth. The extracted
cancellous bone was packed into the cage cavity. The amount of
harvested marrow through 1 drill tract is sufficient to pack 1
cage. A Caspar distraction device enlarged the disc space. The
proper size of cages was impacted into the disc space for
fusion. The cage size is available in heights of 6, 8, 10 and 12
B underwent anterior discectomy through the Smith-Robinson
method. The wound over iliac bone was made about 5 cm in length
to allow for proper bone extraction. Autografts were harvested
from the anterior iliac crest with a low-speed oscillating saw.
The tricortical graft was formed using a typical Smith-Robinson
model, and impacted into the previously prepared interspace. All
grafts were placed with the cortical face placed anteriorly.
anterior approach to the cervical spine, intraoperative
identification of the vertebral level and removal of the disc
and osteophytes using pituitary rongeurs and high-speed burrs.
For tricortical graft fusions, we used a Smith-Robinson
technique.15 A transverse curvilinear skin incision was used. We
used the Caspar screw distractor to allow careful distraction of
the disc space throughout the whole procedure. This is enough in
one level disc openings for decompression and smoothly impacting
the graft into the disc space. All end-plate cartilage was
removed with a curette after decompression. Additionally, a
high-speed burr was used to carve the margins of end plates for
better graft fitting. The subchondral bone of the central end
plate was preserved as much as possible. Furthermore, one 3-mm
perforated hole was driven through the end plate above and below
surgery, all patients wore a Philadelphia collar for 6 weeks
postoperatively, followed by a soft cervical collar for 4 weeks.
Neck exercises were initiated 3 months after surgery, and
a gradual return to normal activity levels was permitted.
Patients with iliac autografts were allowed to walk after the
removal of the drainage tube from the donor site. The patients
with cage fusion with cancellous bone extraction by trocar were
allowed to walk immediately after recovering from the
2 months after the operation, follow-up radiographs were taken
every 2 weeks and at 3, 6, 9, 12 and 24 months postoperatively.
Brantigan’s method was used to confirm radiological bone
union.13 The bone was considered fused when there was proof of
uniform bone mass, a bone bridge was found on the plain lateral
radiograph and no movement seen on the flexion and extension
lateral radiograph and when the lordotic and kyphotic angles of
the cervical spine were stable. The change in Cobb’s angle was
assessed by the method designed by Wetzel et al.14 The last
follow-up radiograph was compared with the postoperative
radiograph to assess the cervical lordosis. To assess changes in
interbody space height, the distance between the superior
midpoint of the upper vertebra and the inferior midpoint of the
lower one was measured on both the postoperative radiograph and
the last one taken in follow-up after bone fusion was complete
(Fig. 1). The lordotic angle (postoperative, last follow-up) and
interbody height (postoperative, last follow up) values used in
this study were measured by the author three times every 2
outcomes were assessed by comparing the preoperative and
postoperative neurologic status and correlated subjective
complaints. They were graded from excellent to poor using the
criteria of Odom et al.15 (Table 3). Successful treatment was
defined as the patient achieving improvement of symptoms,
including excellent or good outcome. Failed treatment was
defined as only slightly improving, persisting, or worsened
preoperative symptoms, meaning a fair or poor outcome.
that were collected included patient demographics, union time,
radiographic parameters, clinical outcome, operation duration,
blood loss, hospital days and complications. The data were
analyzed using ANOVA, the paired t test, the chi square test and
the Fisher exact test. Differences were considered to be
significant when p < 0.05.
group A, 23 cases had an excellent and good clinical outcomes
according to odom’s criteria , similar outcomes were repoted
for Group B (Table 4).
taken to achieve good fusion: The two groups had similar
rates of final fusions. The fusion rates were 100% (24 of 24
levels) in the autograft group, and 95.84 % (23 of 24 levels) in
the cage group. The mean time taken to achieve a good fusion in
the cage group was 5.54 months (1.8 to 10) and in the
tricortical graft group 4.2 months (1.5 to 6). There was no
significant difference between the two groups (Student’s
t-test, p > 0.05).
in the interbody height ratio. The anterior interspace
collapse of 1.53 mm in the cage group is less than the 2.72 mm
recorded in the autograft group (p = 0.062). The rate of
collapse in the cage group was less than (p = 0.006) the rate of
collapse in the autograft group.
lordotic and kyphotic angles were assessed by measuring the
change in Cobb’s angle on both the postoperative and the last
follow-up radiographs. Group A patients with cage fusion had
significantly better recovery of normal lordosis than those in
group B. The loss of cervical lordosis of 2.75° in the cage
group is less than
the 5.25° recorded in the autograft group (Table 5).
In the autograft group, the complication rate was 12.9% (3 of 24
patients), including one patient with a broken graft, one
patient with graft dislodgment and one patient with hematoma and
paresthesia at the donor site. No avascular necrosis occurred in
the implanted autografts. In the cage group, the complication
rate was 8.1%, with one patient having pseudarthrosis and one
patient with transient dysphagia. In the autograft group,
although graft fracture occurred, all of these patients finally
achieved union. The patient with pseudarthrosis in the cage
group had no obvious symptoms and no additional surgery was
done. Fibrous union was impressed for this patient because no
angular change was seen on the stress views. No wound infections
occurred in our series.
average operative time was 75 minutes for group A (range,
60–90), and 92 minutes for group B procedures (range,
75–110). There was no statistical difference detected between
the treatment groups (P = 0.05). The average blood loss for
group A was 115 mL (range 75-160 mL) and 180 mL (range 120-300
mL) for group B was 1.5 days. no statistical difference between
mean hospital stay was 1.75 days (range, 1–5) for group A;
3.75 days (range, 2–8) for group B. There was no statistically
significant difference among the two groups (p = 0.509)
anterior cervical discectomy with interbody fusion is an
effective and practical procedure for treating patients with
segmental degenerative disease of the cervical spine. Cervical
spine interbody fusion using an autograft from the iliac crest
has achieved favorable clinical outcomes and is the gold
standard for treating patients with degenerative cervical
disease. Robinson et al16 reported the first large series of
patients with cervical radiculopathy treated with anterior
interbody fusion, 94
percent of the patients with single level disc disease in
his series achieved good or excellent outcomes. The overall
succsess rate in our series was comparable and the two groups
had similar clinical results.
et al.17 reviewed serial x-rays after anterior cervical fusion
was performed in an aggregate total of 139 levels in 98 patients
and found arthodesis in 97% of patients who underwent autograft
procedures. Savolainen et al.18 found a 98% fusion rate in
patients who underwent procedures with autograft but reported
donor site complications in 16% of the patients. Matge10
reviewed patients who had undergone AICG fusion procedures and
found that there were many graft related complications,
including migration (2.1–4.6%), kyphosis (3–10%),
pseudoarthrosis (1–3%), and donor site hematoma, pain, or
infection with donor site complication rate of 22% in their
series. We had fusion of all the 24 cases of the autograft but
with one case with donor site morbidity.
cages have been developed to replace autografts.10, 19-24
Interbody cages provide various advantages, including immediate
stability, maintenance of a constant height (constant interbody
space), containment of material permitting osteoconduction, and
improvement of cervical lordosis. Interbody cages also have a
lower profile than plate constructs, and are associated with a
low failure rate. Cho et al 21 and Vavruch et al 24 reported
that interbody cages could provide solid fusion, increased
cervical lordosis, and increased disc height with few
complications; however, cage subsidence25 may occur and cause
decreased disc height. In our study, the collapse rate in the
cage group (6%) was significantly less than the collapse rate in
the autograft group (16.1%). Moreover, loss of anterior disc
height and loss of cervical lordosis were significantly less in
the cage group.
our study, the wound incision at the donor site in the cage
group was small. The harvest of bone marrow through a small,
T-shaped bone graft harvesting set was simple and produced less
trauma than other methods, therefore minimizing donor site
complications in our cage group. In our study, no
pseudoarthrosis or cage migration was encountered. In our study
the fusion rates in the PEEK and AICG groups were comparable and
the clinical results were satisfactory.
of Hospital Stay
et al.26 reported that the use of
cages in the cervical spine reduced length of
hospitalization and allowed earlier return to daily activities
by providing immediate fixation and pain reduction and
maintaining the correct interbody space. In particular, they
found that the use of a cage provided early stability with no
collapse or dislodgment on follow-up examination, and eradicated
donor site complications. In our study, patients, who underwent
anterior cervical discectomy with cage fusion, showed a
significantly better recovery of normal lordosis than the other
significantly better preservation of the interbody space.
Although the operating time was shorter in group A, the clinical
results were not statistically different between the two groups
(p = 0.360). The reason for the longer operating time in group B
is the required meticulous preparation of the iliac bone,
comparison with non instrumented anterior cervical discectomy
and fusion (ACDF) with cervical cages is expected to improve
upon such variables as procedure time, duration of hospital stay
and postoperative blood loss. Procedure times for ACDF ranged
from 77 to 174 minutes in three studies11,18,27, In contrast,
operative time for one level Cage operations was reported by
Hacker et al.28 to average 92 minutes, although no significant
difference was found between operative times for the Cage groups
and the (ACDF) group.
hospital stay duration, Castro et al27 reported that hospital
stay and operative time were reduced significantly by the use of
a cage. However, there was no difference among the two groups in
terms of hospital stay. Hacker et al.28 reported an even shorter
average hospital stay for his cervical cage patients (1.5 days),
which compares favorably with reported hospital stays of 1.6 to
2.2 days for plate patients27. Similar results have been
reported for clinical trials of multiple cage types lending
support to the conclusion that cage implantation results in
shorter hospital stay and earlier return to work, improving the
cost-effectiveness of anterior cervical arthrodesis procedures29.
of intraoperative blood loss for cervical fusion cages is scarce
in the literature; Hacker et al.28
reported significantly less average intraoperative blood
loss for the cervical cage patients over other groups. Results
from the present study are largely consistent with those in the
literature: Cage procedures had blood loss similar to dowel
procedures (Cage, 142 cc; Tricotical autogenous iliac graft, 121
cc; plate, 289 cc).
ideal cervical fusion approach would offer fusion rates and
clinical success of 100% with minimal expense, avoid painful
autograft sites, incorporate quickly, obviate the need for a
cervical orthosis, and have no associated soft tissue morbidity.
Cages had similar fusion success rates to the tricortical
autogenous iliac graft with a concomitant improvement in
clinical outcomes. Furthermore, the use of the fusion cage may
mitigate the need for painful hip graft harvest.
cervical fusion cage was not associated with the breakage or
dislodgment in this study that has been noted to occur other
authors. The obvious advantage of the cage over current
available options is the ability to use cancellous autograft
leading to potentially more rapid bone incorporation while
avoiding a painful remote donor site. Other considerations
include a no profile internal fixation device and ease of
operative technique as evidenced by no additional operative time
to that needed for the standard graft technique.
Although cervical spine surgery is an
evolving technical challenge, the results presented here suggest
interbody fusion cages are as good as, if not better than,
autogenous iliac bone-only fusions for the treatment of disc
related disorders. Cage can be used as an alternative surgical
treatment modality after one-level anterior cervical
decompression procedure for single-segment degenerative cervical
spine and can provide early stability, maintain the interbody
space and cervical lordosis, reduce operation time and minimize
complications at the bone graft donor site.
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