|
Original Scientific Article
Abdominal Adhesions to Prosthetic Mesh Evaluated by Laparoscopy
and Electron Microscopy
Michael L Baptista, MD, Margaret E Bonsack, MS, Isaac Felemovicius,
MD, John P Delaney, MD, PhD, FACS
Background: Most adhesion experiments involve observations
at a single time point. We developed a method to evaluate abdominal
adhesions to surgical mesh by sequential laparoscopy.
Study Design: An abdominal wall defect was created
in rats and repaired with polypropylene mesh. Sequential laparoscopic
evaluation of adhesion formation was performed in each animal.
The percentage of mesh area involved was scored (0% to 100%).
At various time intervals animals were sacrificed and samples
were obtained for light and scanning electron microscopy.
Results: Adhesions were already present on day 1, increased
by day 7, and did not progress thereafter. Mesh surfaces free
of adhesions were covered with a confluent mesothelial cell layer,
first seen by scanning electron microscopy on day 5 and complete
by day 7.
Conclusions: Intraabdominal adhesions are best studied
by sequential laparoscopy. Adhesions develop within 1 day of
prosthesis placement. Adhesion-free surfaces are carpeted with
mesothelial cells by day 7 and remain free thereafter, for duration
of study.
Abdominal wall hernias can often be
repaired by suture approximation of the edges of the defect.
But this approach is followed by a high incidence of recurrent
herniation.1 The use
of permanent synthetic prosthetic mesh materials provides a more
secure repair, particularly for large defects.1,2
Frequently, there is no viable tissue available to separate the
synthetic material from direct contact with the abdominal viscera,
in which circumstance, adhesions of omentum and intestine always
develop. One potential complication of such adhesions is intestinal
obstruction. A more serious problem is
that of intestinal fistulization through the junction of the
prosthetic material with the abdominal wall.3-5
The most commonly used meshes are knitted,
are macroporous, are synthesized from polypropylene or polyethylene,
and share the potential for causing intestinal complications.3,5,6 An ideal prosthesis would not induce intraabdominal
adhesions but at the same time would firmly incorporate into
the abdominal wall. Smooth-surfaced impermeable materials, such
as silicone, which effectively resist adhesion formation, do
not develop the necessary fixation to the adjacent fascia and
muscle.
Several experimental models have been
used to investigate these issues.7-9 Time
intervals for observation after prosthesis installation have
varied from hours to months, but always involved a single observation
per animal. We suggest here that adhesion formation is better
studied by sequential observations than at a single arbitrary
time.
The purpose of this article is to describe the dynamics of
visceral adhesion formation to polypropylene mesh. The major
innovation reported here is the use of repeated peritoneoscopy
to allow serial observations and surgical manipulations of adhesions.
The first set of experiments addressed the questions: 1) What
role does omentum play in adhesion formation? and 2) What is
the significance of the tissue backing the porous prosthesis,
ie, peritoneum versus subcutaneous tissue? These observations
were made at necropsy. The second group of studies involved repeated
laparoscopy to determine adhesion dynamics, and timed sacrifice
to obtain tissues for scanning electron microscopy of the prosthetic
surface.
METHODS
Animals
Female Sprague-Dawley rats weighing between 275 and 325 grams
were used. All rats were kept at least 1 week before operation
to adjust to the laboratory environment. During this time they
received standard lab chow and water, ad lib. They were housed
in a temperature- and humidity-controlled environment with a
12-hour light-dark cycle. The animals were cared for by the University
of Minnesota Research Animal Resources Department in accordance
with the principles in the Guide For Care and Use of Laboratory
Animals, NIH publication, revised 1993.
Surgical technique
Rats were anesthetized with an IP injection of sodium pentobarbital
(30 to 40mg/k). The abdomen was shaved with an electric clipper
and prepared with povidine-iodine solution. Procedures were done
under aseptic conditions.
Abdominal wall resection and omentectomy: necropsy studies
Preliminary studies were done to assess the effects, with
respect to adhesions, of the tissue backing the porous mesh—subcutaneous
tissue versus peritoneum. It was our initial impression in this
rat model that omentum had a greater propensity to adhere to
polypropylene mesh than did intestine. This proposition was tested
by removing the omentum in some animals.
In one group the polypropylene mesh was sewn around its periphery
to the peritoneal surface on either side of a midline incision.
Peritoneum, muscle, and skin were then reapproximated, so the
prosthetic material had underlying peritoneum. In other animals
an abdominal wall defect was created, preserving the skin and
subcutaneous tissue but excising muscle and peritoneum. The outer
surface of the mesh was exposed to the subcutaneous tissue rather
than to peritoneum, mimicking the clinical situation. In another
group of rats omentectomy was performed to observe the consequences
on adhesion formation. So, four preparations were studied: with
or without abdominal wall resection and with or without omentectomy.
The groups were prepared sequentially with no attempt at randomization.
Adhesions to mesh were evaluated by sacrificing the animals 30
days or more after operation. Data were analyzed and groups compared
by two-way analysis of variance followed by inspection of differences
between pairs of means by Duncan's multiple range test.
Adhesion dynamics: laparoscopy
In subsequent studies we used the model found to have maximum
adhesion formation, namely, abdominal wall resection and preserved
omentum. These animals were studied by repeated laparoscopy starting
at day 1 and at chosen intervals, 3, 7, 14, and 28 days after
mesh installation. Additional animals were subjected to this
preparation and sacrificed at days 1, 3, 5, 7, 14, and 28 solely
to obtain samples for scanning electron microscopy. The rats
were arbitrarily designated as to sacrifice date at the time
of mesh placement.
Technical considerations
Pilot studies demonstrated that interrupted sutures encouraged
omentum or intestine to adhere to the cut edge of the prosthetic
material, occasionally even to permit visceral herniation between
sutures into the subcutaneous space. We subsequently used continuous
monofilament polypropylene suture, everting the edge of the prosthesis
and the cut edge of the abdominal wall away from the abdominal
cavity. Even with this method there was some propensity for adhesions
to form at the abdominal wall to prosthesis intersection.
A technical detail that proved important
was that of skin closure. Some investigators have reported problems
with skin dehiscence in the rat after laparotomy.8-10
In our hands, the association of an abdominal wall defect, polypropylene
mesh, and simple skin approximation with interrupted or running
nonabsorbable material frequently failed because the animal chewed
on the sutures with resulting skin separation. The use of running
intradermal absorbable suture eliminated this problem. An associated
observation was that when the skin edges did separate and expose
the mesh, extensive dense adhesions covered the intraabdominal
surface under the exposed area. So any animal that developed
skin dehiscence was discarded from further consideration. Of
the 28 animals prepared for these studies 3 were eliminated because
of skin breakdown (Table 1).
Table 1. Effect of Omentectomy and Abdominal Wall Resection,
or Both, on the Area of Polypropylene Mesh Involved with Adhesions
|
|
|
|
Mean |
|
|
|
|
|
|
|
Group |
No. of animals |
n |
% |
Range (%) |
|
|
O + AWR + |
7 |
8* |
48 |
18–75 |
|
O – AWR + |
7 |
3* |
93 |
5–100 |
|
O + AWR – |
5 |
10* |
16 |
0–51 |
|
O – AWR – |
6 |
13 |
67 |
25–100 |
|
* Values are significantly different from each
other, p < 0.05. AWR, abdominal wall resection; O, omentectomy.
Data are means with standard error of the mean in parentheses.
Laparoscopy
To test the tolerance of the rat to abdominal insufflation
for laparoscopy a bulb pump was used to inject room air. A 25-gauge
needle was inserted into the abdominal cavity and room air was
slowly instilled while ventilatory rate and pattern were observed.
Intraabdominal pressure up to 20 mmHg did not cause respiratory
alterations. Seven mmHg was found to provide enough space for
laparoscopic observations; subsequent exams were done without
pressure measurements, simply instilling sufficient air to allow
the needed visualization.
To accomplish the examination, an 8-mm skin incision was made
in the flank 4 cm lateral to the umbilicus. A 5-mm Auto Suture
Surgiport (Auto Suture Co, Norwalk, CT) beveled cannula was inserted,
through which a 4-mm Comeg arthroscope (American Medical Endoscopy,
Miami Beach, FL) was introduced. A Karl Storz Xenon Light Source
610 (Karl Storz Endoscopy-America, Culver City, CA) was attached.
Observations were video recorded.
Magnification obtained with this set-up varied depending on
the distance from the end of the scope to the tissue. With the
tip close to the observed surface, magnification on the monitor
was approximately 80 times. This allowed remarkably clear visualization
of the microvasculature.
To quantitate adhesions, the prosthetic patch was visually
divided into four equal quadrants (Fig. 1). Adhesions covering
the mesh were estimated according to area of attachment, ranging
from 0% to 100% (no adhesions to completely covered). The intraabdominal
structure involved, omentum or intestine, location of adhesions,
and surface appearance of uninvolved mesh were noted and recorded.
After the examination was completed the scope and cannula were
removed and the skin closed.
Figure 1. Laparoscopic images obtained on days 7, 14,
and 28 after initial operation. The mesh is visually divided
into four equal quadrants and adhesion area estimated. The edematous
omentum on day 7 becomes translucent on days 14 and 28, exposing
to the view the fibers of the underlying mesh. Individual fibers
of the polypropylene mesh are easily seen, as is the vasculature,
an advantage of laparoscopy.
Adhesiolysis
One group of six rats was studied for reformation of adhesions
after laparoscopic adhesiolysis 1 week after abdominal wall resection
and initial mesh placement and at intervals thereafter to assess
possible reformation of adhesions. In this study, the firmness
of the adhesions was scored on a scale of 1 to 3. A score of
1 meant they were loosely adhered and came free when the abdomen
was inflated or by gentle probing with the tip of the scope.
A score of 2 indicated moderate adherence such that the tissues
required separation with a grasper and more vigorous blunt dissection.
A score of 3 indicated firmly attached strong adhesions that
had to be divided sharply. Hemostasis was obtained by compressing
an instrument against the site of bleeding. Cautery was not used
to avoid new adhesion formation secondary to thermal injury.
Histology
Animals were sacrificed with 100mg/kg IP injection of sodium
pentobarbital. The abdomen was opened approximately 2cm from
the prosthesis on the caudal and both lateral aspects of the
prosthesis. The abdominal wall was carefully lifted in order
to observe and score adhesions to the mesh. The entire prosthesis,
adjacent abdominal wall, and adherent structures were then completely
removed by incising 2cm from the cephalad edge of the polypropylene.
The specimens were rinsed in saline, pinned on corkboards, and
fixed in 10% neutral buffered formalin for 48 hours. They were
cut into quarters to produce four samples, each of which included
normal abdominal wall, prosthesis, and the transition area between.
Tissues were routinely processed in an Autotechnicon (The Technion
Co, Chauncey, NY) and embedded in paraffin. Samples were sectioned
at 5 micrometers and stained with hematoxylin and eosin. To focus on collagen, a second set of slides
was stained with sirius red plus hematoxylin according to the
method of Junqueira and associates.11 Sirius
red is a strong anionic dye with sulphonic acid groups that stains
collagen by reacting with basic groups in the collagen molecule.
Collagen birefringency was enhanced by polarization. Histologic
specimens were evaluated by a microscopist who was always unaware
of their origin.
Scanning electron microscopy
One rat was sacrificed on postplacement days 1, 3, 5, and
14, two on day 28, and three on day 7. Tissues were prepared
for scanning electron microscopy as follows. Immediately after
opening the abdomen the surgical mesh and surrounding area were
flooded with 2.5% glutaraldehyde in 0.1M cacodylate buffer. A
1×1-cm sample of mesh, including an area with and another
without adhesions, was removed and put in fresh glutaraldehyde
buffer fixative overnight. The sample was then rinsed in 0.1M
cacodylate buffer 3 times for 20 minutes each, and postfixed
on ice with 1% osmium tetroxide in 0.1M buffer for 30 minutes.
Samples were then rinsed in buffer, dehydrated in increasing
alcohol series (50%, 70%, 80%, 95%, and 100%), and critical point
dried in a Tousimis Model 780 A (Tousimis Research Corporation,
Rockville, MD). Sputter coating with gold and palladium particles
of 10nm was done. Observations and photographs were obtained
using a Hitachi S-450 S and a Hitachi 4700 computerized scanning
electron microscope (Hitachi Instrument Inc, Nissei Sangyo America,
Ltd, Mountain View, CA).
RESULTS
Single observations at sacrifice: omentectomy and abdominal
wall resection
In the absence of omentum, adhesions to the mesh were significantly
fewer with or without abdominal wall resection than if omentum
had been preserved. When the omentum was present, adhesions were
far more prevalent if the abdominal wall had been resected. The
most extensive adhesion formation to the surgical mesh developed
with the combination of abdominal wall resection and intact omentum
(range 75% to 100%) (Table 1).
Laparoscopic observations
Adhesions previously seen laparoscopically were compared with
postmortem observations in the same animals. Necropsy observations
tended to underestimate adhesion area. Details such as the presence
of adipose cells, which identified adherent omentum, were seen
with laparoscopic magnification but could not be appreciated
at autopsy. The thin clear membranous omentum once adhered to
the mesh was difficult to recognize as an adhesion by a single
observation at necropsy but was readily identified by sequential
laparoscopy.
Adhesions tended to attach first to the mesh and abdominal
wall interface, then extended to cover larger areas of the mesh
surface. It was very unusual to see adherence to the central
surface without edge involvement.
At laparoscopy 24 hours after operation one could appreciate
tissue swelling and initial growth of microvessels along the
cut edge of the muscle. Some omental adhesions were invariably
present by 24 hours. Adhesion-free areas of mesh had a shiny
translucent surface. The interstices were sealed, as evidenced
by the fact that no injected intraperitoneal air escaped through
the mesh into the subcutaneous space, judged by inspection and
palpation. In some instances a seroma was already present in
the subcutaneous space contained there by the now relatively
impermeable mesh.
Three days after placement of the prosthesis, microvessels
could be seen growing onto the surface from the cut edge of the
peritoneum. By day 7, the area involved with adhesions had increased
compared with days 1 and 3. Blood vessels growing from the wound
edges toward the center of the prosthetic patch were beginning
to anastomose with omental vessels. Blood flow in small arteries
was generally from the abdominal wall toward the adhesions, but
in some animals bidirectional flow could be seen.
By day 14 edema and inflammation had subsided. There was no
change in the extent of adhesions as compared with day 7. Microvascular
anastomoses were more extensive.
On day 28 adhesions to the mesh were identical to those found
on days 7 and 14. Strands of polypropylene were readily visible
through the now translucent omentum (Fig. 1). At this time the
adhesions had become firmly fixed to the mesh. The initial erythema
and edema had disappeared. Wound contraction was evident from
the fact that the center of the mesh folded inward toward the
abdominal cavity and the original 2.5×2.5-cm abdominal
wall defect was now diminished in size.
Table 2 summarizes the laparoscopic estimations of mesh area
involved with adhesions. The most important observation is that
those areas free of adhesions on day 7 remained so on subsequent
examinations; that is, the adhesions did not progress.
Table 2. Percent of Polypropylene Mesh Area Covered by
Adhesions Estimated by Laparoscopy after Abdominal Wall Resection
with Preservation of Omentum
|
|
|
Observation day |
|
|
|
|
|
1 |
3 |
7 |
14 |
28 |
|
|
n |
7 |
4 |
25 |
23 |
23 |
|
Mean, % (range) |
58
(5–100) |
84
(67–100) |
91
(75–100) |
90
(75-100) |
91
(75–100) |
|
Light microscopy
Histologic preparations were difficult to obtain on day 1
because of weak attachment of the prosthetic fibers to the abdominal
wall. During processing the mesh separated from the fragile adhesions
and from the abdominal wall. Adequate histologic specimens were
first obtainable on day 3, at which time the fibers of the mesh
were seen to be coated by adhesions or by scattered cells, mostly
neutrophils and fibroblasts. Macrophages were more prominent
than on day 1. The samples did not yet demonstrate significant
collagen deposition as judged by polarizing microscopy of sirius
red stained samples.11
On day 7 inflammation was still present but the population
of neutrophils had decreased. Macrophages were prominent around
the polypropylene fibers (Fig. 2). Some fibroblasts were present
but little collagen had yet infiltrated between mesh fibers.
Figure 2. Histology of the abdominal wall with polypropylene
mesh. On days 1 and 3 inflammatory cells surround mesh fibers.
On day 7 inflammation is still present but the predominant cells
are macrophages. On day 28 most of the acute inflammation has
subsided and histiocytes are now prominent. Hematoxylin and eosin
stain, original magnification ×100.
Tissues harvested on day 28 had well-formed collagen interposed
between the threads, along with macrophages and fibroblasts.
The mesh was firmly incorporated into the abdominal wall by fibrous
tissue. At the intersection of the sutured junction collagen
was more abundant than at the center of the mesh (Fig. 3).
Figure 3. Distribution of collagen on day 28 shown
by polarizing microscopy. The density of collagen is maximal
at the muscle-mesh interface, seen as white to light gray. Arrows
point to the muscle wall prosthesis intersection. The holes left
behind by the individual mesh fibers after histologic preparation
are marked with asterisks. Picrosirius red stain, original magnification
×40.
Adhesions always involved omentum and sometimes intestine.
The bumpy adhesion-free surface seen at laparoscopy proved on
histology to represent mesh fibers surrounded by histiocytes
and fibrous tissue. The surface of the prosthesis facing the
abdominal cavity demonstrated a layer consistent with mesothelial
cells.
Scanning electron microscopy
On day 1 after operation, the polypropylene threads of the
mesh were bare, as seen at low magnification scanning electron
microscopy. Most of the polypropylene was directly exposed, with
no tissue coverage. Omentum was attached to the mesh-abdominal
wall interface with an abundant framework of fibrin. Fibroblasts
were present in small numbers. Leukocytes were apparent in the
spaces between the polypropylene threads. Few cells were attached
to the mesh fiber surfaces at this time. Mesothelial cells were
not yet identifiable.
On day 3 most of the surface of the polypropylene mesh was
covered by a thin layer of tissue. Fibroblasts had increased
since day 1, mostly in the crevices between mesh fibers. The
fibrin framework was more dense, and it extended onto the areas
free of adhesions. Still no mesothelial cells could be seen.
By day 5 the entire surface of the mesh was covered and mesothelial
cells had appeared (Figs. 4 and 5). Their characteristic microvilli
were relatively sparse.
Figure 4. Scanning electron microscopy of an adhesion-free
surface at low magnification on days 1, 3, and 5. On day 1 after
operation, the mesh fibers are readily seen with few attached
cells. The fibers are partially covered on day 3. On day 5 they
are completely coated with a cellular layer (original magnification
×30).
Figure 5. Scanning electron microscopy of the prosthesis
surface on days 7 and 28 after implantation. On day 7 the surface
of the mesh shows elevations corresponding to the polypropylene
fibers (original magnification ×25). Detail of this adhesion-free
area demonstrates the surface to be completely carpeted with
mesothelial cells (original magnification ×1,500). Depressions
are seen on the surface corresponding to the interstices of the
mesh (original magnification ×15). The surface on day 28
is covered with mesothelial cells as on day 7 (original magnification
×1,200).
By day 7 there were no bare polypropylene fibers. Leukocyte
infiltration had subsided. The surface of the mesh was covered
with a confluent carpet of mesothelial cells with abundant microvilli
(Fig. 5). The surface on day 14 was similar to that seen on day
7.
On day 28 the abdominal surface of the mesh and the holes
around the mesh fibers were covered by mesothelial cells (Fig.
5). Microvilli were more dense than on day 7. Macrophages were
seen adjacent to omental adhesions.
Adhesiolysis
One week after mesh installation at least 75% of the surface
was covered by adhesions. After mechanically separating the adhesions
from the mesh subsequent exams demonstrated only a few small,
newly formed adhesions. In 19 observations after day 21, no new
adhesions developed (Table 3).
Table 3. Percent of Mesh Area Covered by Adhesions after
Adhesiolysis
|
|
Day |
7 |
14 |
21 |
28 |
100 |
280 |
|
|
1 |
73% (3) |
7% (2) |
0% (0) |
6% (1) |
0% (0) |
0% (0) |
|
2 |
100% (3) |
25% (1) |
0% (0) |
0% (0) |
0% (0) |
0% (0) |
|
3 |
94% (3) |
– |
0% (0) |
0% (0) |
– |
– |
|
4 |
94% (3) |
– |
0% (0) |
0% (0) |
0% (0) |
0% (0) |
|
5 |
92% (2) |
0% (0) |
14% (1) |
0% (0) |
0% (0) |
0% (0) |
|
6 |
98% (2) |
0% (0) |
4% (1) |
0% (0) |
6% (–) |
6% (–) |
|
Mean |
92% |
4% |
3% |
1% |
1% |
1% |
|
Lysis was performed whenever adhesions were found. The percentages
represent the area of adhesions before lysis. Of the 21 exams
performed after the initial seventh day adhesiolysis, 17 showed
no further adhesions. Adhesiolysis scores are in parentheses:
0, no adhesions; 1, freed with inflation or scope tip; 2, required
grasper blunt dissection; and 3, required sharp dissection.
DISCUSSION
A provocative finding was that adhesion formation did not
progress after day 7. Any area of mesh surface free of adhesions
then remained so thereafter. The uninvolved surface was shiny
and translucent. These observations indicate that an adhesion-resistant
intraabdominal surface develops on polypropylene mesh within
a week of installation. One might speculate that fairly short-lived
protection by mechanical separation or biochemical inhibition
could result in permanent freedom from adhesions between prosthetic
mesh and abdominal viscera. Along the same lines, the adhesiolysis
study suggests that if one were to mechanically break down adhesions
to prosthetic mesh after 7 days, they would likely not reform.
Such is not the case when visceral adhesions to injured peritoneum
are divided. Both clinical and experimental
observations indicate that subsequent to such lysis newly formed
adhesions are often more extensive than the original.12,13
Laparoscopic findings of progression of adhesions up to day
7 and a stable adhesion-resistant surface thereafter correlates
with the scanning electron microscopic findings of a mesothelial
cell coating, which is not complete until then.
That mesothelial cells prevent adhesions
is well documented.14-16 Human omental mesothelial
cells in vitro produce hyaluronic acid.14 Jones and colleagues14
noted that ovarian cancer cell adherence in multiwell plates
was prevented by a confluent mesothelial cell culture. The content
of hyaluronic acid in the medium was found to be elevated. After
hyaluronidase pretreatment the blocking of adhesions was abrogated.
Whitaker and associates15 reported that a pure culture of
mesothelial cells was able to induce fibrinolysis. Another study16
suggested that the mesothelial fibrinolytic properties are associated
with the secretion of tissue plasminogen activator. These results
likely explain the observation that once the polypropylene mesh
surface is populated with mesothelial cells it remains resistant
to new adhesions.
In a relevant study by Raftery,13 a parietal peritoneal defect
was surgically created. Sequential transmission electron microscopy
was used to study healing. On postoperative day 3 a "primitive
mesenchymal cell" appeared on the surface. On day 4 these
cells were seen to have some microvilli. By day 5 mesothelial
cells with mature microvilli were identifiable. By day 8 and
later a complete layer of mesothelial cells covered the defect.
The new mesothelium was believed to arise from subperitoneal
connective tissue, whether from primitive mesenchymal cells or
from fibroblasts was uncertain.13 These observations are in agreement
with the time course of mesothelial cell coverage of prosthetic
mesh observed in the present study.
Time of observation: sequential laparoscopy versus sacrifice
Adhesion formation is a dynamic process and sequential evaluation
over an extended period of time provides important information.
We found that peritoneoscopy could be undertaken at any chosen
interval after placement of the prosthesis, allowing repeated
in vivo observations of adhesion development. Information with
respect to angiogenesis and blood flow in the microvasculature
can be assessed nicely with the high magnification obtained at
laparoscopy. The early time course, site, and progression of
adhesion formation can be determined only with repeated in vivo
visualization. Such ongoing changes are impossible to appreciate
by single observations at sacrifice. Because variations occur
among subjects, sacrifice with a single observation time and
averaging the results is less meaningful than laparoscopic observations,
where each animal provides multiple data points.
The extent of adhesions may be underestimated at necropsy
exam. The thin transparent omental membrane once firmly incorporated
onto the mesh may be recognized as an adhesion only if previously
observed during early stages of attachment.
In conclusion, evaluation of intraabdominal adhesions to prosthetic
mesh is best accomplished by means of sequential laparoscopy
with each animal serving as its own control. Adhesions are already
present 24 hours after operation. The area involved progresses
during the first week. Segments of prosthetic mesh surface free
of adhesions at 7 days remain uninvolved thereafter. The development
of an adhesion-resistant surface coincides with formation of
a confluent mesothelial cell coating. After mechanical separation
(adhesiolysis), very few new adhesions form between abdominal
viscera and prosthetic mesh. In this model, omentum has a greater
propensity to adhere to mesh than does intestine and tends to
attach first at the mesh abdominal wall interface.
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Genzyme Corporation supplied some laboratory material; no
author has any relationship with the company.
Received May 19, 1999; Revised September 20, 1999; Accepted
October 1, 1999.
From the Department of Surgery, University of Minnesota Medical
School, Minneapolis, MN, USA.
Correspondence address: John P Delaney, MD, PhD, FACS, University
of Minnesota, FUHC, Box 89, 420 Delaware St SE, Minneapolis,
MN 55455.
JACS |
