Vol 8, No 6, November/December 2000
339
Adcon-L (Gliatech, Inc, Cleveland,
Ohio) is a sterile absorbable gel
matrix composed of a gelatin in a
carbohydrate polymer. The material
is biodegradable, does not incite
any inflammatory reaction, and is
reported to disappear completely
within 21 days after implantation.
Animal studies have shown that
Adcon-L (or its prototypes) can
reduce the development of fibrotic
epidural scars in rat, rabbit, and
dog laminectomy models.
1,2
On
the basis of subsequent studies in
dog laminectomy and diskectomy
models, as well as a large prospec-
tive multicenter randomized trial
performed in Europe,
3
the US Food
and Drug Administration (FDA)
recently approved Adcon-L as a
device (rather than as a drug) for
marketing in the United States.
Since receiving approval in May
1998, Gliatech has been marketing
Adcon-L with the following FDA-

first studied this issue in 1948
when they reported epidural scar
formation after laminectomy and
diskectomy. They theorized that
the postoperative adhesions were
derived from the surgically dam-
aged anulus fibrosus. Nachemson
5
also supported this early theory
and felt that leakage from the dis-
rupted intervertebral disk was a
causative factor in epidural fibrosis.
However, LaRocca and Macnab
6
felt
that this “laminectomy membrane”
was actually a layer of fibrotic tis-
sue that covered the laminectomy
site as a result of migration of
fibroblasts from the raw surface of
the erector spinae musculature.
Postoperative epidural fibrosis
can surround nerve fibers, leading
to increasing neural tension and
adhesion to the nerve root. It has
also been theorized that epidural
scar increases the vulnerability of
nerve roots to compression or ten-
sion, which can occur with recurrent
disk herniation or stenosis.

described a new experimental model
in dogs that allowed objective biome-
chanical quantification of the effect
of postoperative scar. The ultimate
load of postoperative adhesions on
nerve roots and the dura was mea-
sured. Their findings suggested a
beneficial effect of hyaluronic acid
in decreasing the biomechanical
strength of extradural adhesions
after laminotomy for nerve root
exploration or disk excision com-
pared with the use of fat graft or no
interpositional membrane.
One of the major questions re-
garding the formation of epidural
fibrosis is its causal relationship to
clinical symptoms. The literature
contains numerous anecdotal reports
of patients with postoperative epi-
dural fibrosis and radicular pain
8,9
;
however, the cause-and-effect rela-
tionship remains to be delineated.
Conversely, recent reports concern-
ing computed tomography (CT) and
magnetic resonance (MR) imaging
studies on patients who have under-
gone laminectomy or diskectomy

postoperative epidural fibrosis
(documented by gadolinium–
diethylenetriamine-penta-acetic
acid MR imaging). There was no
correlation between the postopera-
tive MR findings and the clinical
outcome.
Annertz et al
14
reported on 16
patients evaluated with MR imag-
ing after lumbar diskectomy. Two
matched groups of 8 patients each—
one group being symptomatic and
the other asymptomatic—were
compared. No relationship was
found between epidural fibrosis and
sciatica in the two groups. Addi-
tionally, the 8 symptomatic patients
underwent reexploration and neu-
rolysis of the adhesion; 6 (75%) had
no statistically significant benefit
from the second surgical procedure.
The authors of this study concluded
that epidural fibrosis alone was not
the cause of the symptoms, as surgi-
cal release of these adhesions did
not result in patient relief.
The prevention of epidural fi-
brosis has been a field of intensive

Jeffrey S. Fischgrund, MD
Vol 8, No 6, November/December 2000
341
tions, 34% underwent procedures
involving multiple levels, and 58%
underwent simple disk-herniation
surgery.
A prospective randomized study
by MacKay et al
10
included 156 pa-
tients who were treated surgically
for lumbar disk herniations and
randomly assigned to one of three
groups. All patients underwent an
uncomplicated one-level lumbar
laminectomy for disk herniation. In
two groups, either fat or gelatin
foam sponge was placed in the
laminectomy defect; in the third
group, no interposition membrane
was used. The patients were as-
sessed at 1 year. Overall, the extent
of epidural scar formation was
rated excellent or good in 83% of
the patients. The authors concluded
that the clinical outcome after disk
surgery did not correlate with the
use or type of interposition mem-
brane placed to prevent epidural

score of 4 indicating that more than
75% of one quadrant was filled with
scar. Overall, the authors concluded
that the amount of scarring was a
significant (P = 0.009) predictor of
recurrent radicular pain. Those
patients with extensive scar forma-
tion (scar score of 4) were 3.2 times
more likely to experience recurrent
radicular pain than patients with a
scar score of less than 4.
Several components of pain were
measured in that study, including
pain when most severe, pain on
average, and pain at the end of the
day. Only the “pain on average”
and the “pain when most severe”
measures were analyzed. Only the
latter measurement correlated sig-
nificantly with scar formation.
This study still leaves unanswered
several questions about the role of
epidural fibrosis in postoperative
radicular pain. Only 14 (17%) of the
84 patients who had extensive scar
(grade 4) had recurrent radicular
pain (most severe). The other 83%
of the patients with extensive scar
reported no radicular pain. There-
fore, there must be factors other than

raised by this FDA audit call into
question the accuracy of the entire
study.
In an animal study, Einhaus et al
1
examined seven adult mongrel dogs
on which multiple-level unilateral
hemilaminotomy and annular fen-
estration were performed. In each
animal, Adcon-L was applied to
two randomly assigned sites around
the diskectomy, the nerve roots, and
the hemilaminotomy. Identical
surgery was performed on a third
site in each animal, but no interposi-
tion membrane was placed. The rel-
ative amount of anterior scarring
around the diskectomy site and pos-
terior scarring at the hemilaminot-
omy site was assessed histologically,
as was the extent of healing of the
annular defect. The authors found
that Adcon-L significantly (P<0.05)
reduced epidural fibrosis in this
model and did not inhibit healing of
the anulus fibrosus.
The large European clinical study
by de Tribolet et al
3
deserves care-

scar formation was given a score
from 0 to 4 based on the percentage
of fibrosis within a quadrant. Post-
operative outcome was assessed
with an activity-related pain ques-
tionnaire, the straight-leg-raising
examination, and a clinical assess-
ment of pain. A single radicular fac-
tor score for each patient was then
determined on the basis of the
scores for 5 of 12 specific daily activi-
ties evaluated on the activity-related
pain questionnaire.
Analysis of the postoperative MR
results demonstrated a significant
(P = 0.002) reduction in epidural
scar formation in patients treated
with Adcon-L (Table 1), similar to
the results in previous animal stud-
ies.
1
These results were supported
by the clinical findings in a small
group of patients who underwent
reoperation at some point between
the first postoperative week and as
long as more than 1 year later. Nine
of the 11 patients had no nerve root
adhesion or only minimal adhesion
around the nerve root, and 8 had no

nerve root, which has not been
proved to affect low back pain.
Furthermore, Adcon-L–treated
patients also had improved scores
on straight-leg-raising examination
on the operative as well as the non-
operative side. The authors found
this improvement particularly
important, because they believe
this clinical test is the standard
used by many surgeons for assess-
ment of postoperative outcome.
The European clinical study did
not report any complications
directly attributable to the use of
Adcon-L. There was no effect on
wound healing, and the incidence
of postoperative infection was not
increased compared with the con-
trol group. However, there are the-
oretical concerns regarding its use
after incidental durotomy. Because
this product decreases the inci-
dence of postoperative epidural
scar by decreasing the inflammatory
response, there may also be persis-
tence of dural leaks. Small dural
lacerations can occur during rou-
tine surgery and may go unnoticed
by the operating physician. During

been conclusively shown that this
reduction in epidural scarring
translates into improved patient
outcome.
If the treating surgeon is of the
opinion that there is a need for a
product to reduce epidural scar, use
of this product may be worthwhile.
Table 1
Distribution of Scar Based on MR Imaging in Study by de Tribolet et al
3
No. of Evaluable Patients (%)
Extent of Scar Adcon-L–Treated (n = 127) Control (n = 139)
Minimal or no scar 17 (13) 5 (4)
Moderate 62 (49) 65 (47)
Extensive 48 (38) 69 (50)
Vol 8, No 6, November/December 2000
343
However, it should be noted that
the current charge to hospitals for
one tube of Adcon-L is $495. If it is
estimated that 200,000 laminec-
tomies are performed in the United
States every year, routine use of
Adcon-L would add a rather large
expenditure to the national health-
care bill. Further studies are needed
to evaluate clinical outcomes and
establish the cost-effectiveness of
this procedure.

my membrane: Studies in its evolu-
tion, characteristics, effects and pro-
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7. Abitbol JJ, Lincoln TL, Lind BI, Amiel
D, Akeson WH, Garfin SR: Preventing
postlaminectomy adhesion: A new
experimental model. Spine 1994;19:
1809-1814.
8. Martin-Ferrer S: Failure of autologous
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9. Burton CV, Kirkaldy-Willis WH,
Yong-Hing K, Heithoff KB: Causes of
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reference to clinical factors and

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