Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1562_Библиотеки_им_академика_М_И_Перельмана.pdf
The Surgical Management of Atypical Hernias
221
hernias are discussed, including the importance of wide mesh overlap with appropriate
fixation for durable repair.
Open Approach
Computed tomography scanning helps distinguish a true hernia from laxity of the flank
region that can occur from denvervation of the thoracic nerves. For flank hernias, the incision
is typically made overlying the previous incision, and the scar can be excised if unsightly or
per the patient’s preference. Dissection is carried down through Camper’s and Scarpa’s fascia
to identify the musculature of the abdominal wall. If the hernia sac is encountered, it can be
carefully dissected laterally to the fascial edges. It is preferable to leave the hernia sac intact
and use it to dissect into the preperitoneal space without having to enter the abdomen. If the
abdominal cavity is entered, careful adhesiolysis is needed. If unable to locate the hernia sac,
the layers of the abdominal wall are divided including the external oblique, internal oblique,
and transversus abdominis.
The preperitoneal plane is the ideal plane to place the mesh in flank hernias because it
allows large overlap of a mesh prosthetic. This preperitoneal plane can be dissected at the
fascial edges of the abdominal cavity or by dissecting the hernia sac to the lateral edges of the
fascia. After the preperitoneal space is entered, it is bluntly dissected to allow for a large area
for mesh placement. It can be dissected to the diaphragm superiorly, to the psoas muscle
posteriorly, to the rectus sheath or linea alba medially, and to Cooper’s ligament and the
pelvis inferiorly. The peritoneum is closed if it was entered and all holes closed with an
absorbable suture, excluding the space from abdominal viscera.
The preperitoneal space is measured to choose the appropriate size of mesh. The mesh is
oriented and placed in the space to gauge the appropriate size. Cutting mesh is not usually
recommend; however, most meshes can be cut to size without damaging the mesh to achieve
an appropriately taut and well fitted mesh. The mesh is fixed posteriorly first with transfascial
sutures using a suture passer under direct visualization. The amount of space available to
place transfascial sutures is limited by the iliac crest and other structures. Several approaches
can be used to achieve adequate fixation including transfascial sutures and bone anchor
fixation. The use of bone anchors as an adjunct for mesh fixation to the iliac crest relies on
placement in cortical and cancellous bone. The S1 nerve root and lateral femoral cutaneous
nerve should be identified and avoided when placing bone anchors and the use of C-arm
fluoroscopy should be considered if pelvic placement may endager the acetabulum or
sarcoiliac joint [Carbonell et al., 2005b]. Several manufacturers have developed prepackaged
systems to aide in the delivery of bone anchors. Drills with preset depths are provided and
anchor devices are placed 15-20 mm apart or they can be set along a predetermined course on
the surface of exposed bone based on the size and location of the hernia [Ali and Malata,
2012]. Sutures are then passed through the bone anchor and the selected mesh[Carbonell et
al., 2005a; Carbonell et al., 2005b; Yee et al., 2008].
Alternatively, mesh can be fixed at the edge of the iliac crest, and the mesh can overlap
into the preperitoneal space. This excessive mesh without suture fixation can be glued into
place using commercially available surgical glues. The recommended method of fixation
William W. Hope, William F. Powers and W. Borden Hooks
222
starts posteriorly, then medially, then inferiorly, and lastly superiorly, but this can be based
on the surgeon’s preference. The important point is wide overlap with adequate fixation and
for the mesh to be under “physiologic” tension. It is helpful to ensure the operating table is
neutral and not flexed if this was used to expose this area at the beginning of the operation.
After suture fixation of the mesh, closed suction drains are placed above the mesh depending
on the amount of dissection. The area is irrigated, and the fascia closed using a slowly
absorbing monofilament running suture. Routine postoperative care is employed.
Laparoscopic Approach
Flank hernias can be successfully repaired laparoscopically, but this requires advanced
laparoscopic and dissection skills and knowledge of the details of the retroperitoneal anatomy
to safely perform this operation. CT scanning is recommended due to the complexity and
operative planning required to repair this hernia.
Laparoscopic access is obtained using an open or closed technique per the surgeon’s
preference. Access can be difficult, because the patient is not supine, and landmarks used for
safe access are not available. Safe laparoscopic access is essential and should be done with
caution, especially in the reoperative abdomen. Three to five trocars arranged in a semicircle
configuration are placed opposite the hernia. One port should be an 11- or 12-mm port to
facilitate easy mesh placement, but can vary based on mesh type used and hernia size. Ports
are placed to facilitate good triangulation, visualization of the hernia defect, and dissection of
the colon.
Diagnostic laparoscopy can rule out occult hernias or pathology not identified on CT
scanning. It also shows the surgeon the anatomy around the hernia and in the lateral position.
As always, safe adhesiolysis with laparoscopic scissors or an energy device is performed to
clear the entire abdominal wall of adhesions.
Depending on the size and location of the hernia, the right or left colon will likely need to
be partially or fully mobilized to permit adequate visualization and fixation of the hernia.
This is similar to open and laparoscopic colon mobilization and is aided by having the
patient in the lateral position. Dissection ensues along the white line of Toldt up to the splenic
or hepatic flexure depending on how much of the colon needs to be mobilized. While not
mandatory, taking down the peritoneum at the level of the hernia posteriorly provides a
“pocket” for the mesh and a way for the mesh to be partially covered by the peritoneum.
Taking down the peritoneum is similar to a transabdominal preperitoneal (TAPP) repair.
The surgeon grabs the thin peritoneum and bluntly dissects posteriorly toward the psoas
muscle. This is done as much as needed to provide mesh overlap posteriorly and laterally.
Although laparoscopic repair of the flank hernia does not mandate taking down the
peritoneum, and the mesh can be placed totally intra-abdominally as in a standard
laparoscopic hernia repair, taking down the peritoneum allows wider mesh overlap and
reduces the amount of fixation necessary.
The hernia defect is measured intracorporeally as described previously getting a
transverse and longitudinal measurement. The correct size of mesh and mesh compatible with
intraabodminal placement must be used. The mesh is prepared and placed in the abdomen in
the standard fashion. The four sutures are then pulled up through the abdominal wall using a
suture passer. If the mesh overlaps the iliac crest or ribs on the superior or inferior portion of
The Surgical Management of Atypical Hernias
223
the mesh and transfascial suture fixation is impossible, the options are: 1) to place the sutures
off the periphery of the mesh where the suture can be brought out through tissue and fascia or
2) to use bone anchors to secure the mesh. If you have created a large preperitoneal space
superiorly and inferiorly, a third option is to tuck the mesh in this space and use surgical glue
for fixation.
The mesh can be fixed with additional transfascial sutures if the surgeon prefers and there
is adequate fascia and soft tissue to place additional sutures. The mesh can also be tacked to
the abdominal wall and peritoneum using permanent or absorbable tacks. Tacks should not be
placed where the surgeon cannot feel the adjacent soft tissue with bimanual palpation or in
areas where neurovascular bundles run. Careful attention to the anatomy is crucial to avoid
neurovascular injuries or chronic pain from a misplaced tack or suture.
After mesh fixation, the peritoneum, if dissected, is tacked or glued to partially cover the
posterior portion of the mesh. The abdominal contents are again evaluated for occult bowel
injury and bleeding, and the ports are removed under direct vision, making sure to close
trocar sites greater than ten millimeters. Routine postoperative care is provided.
Data related to incidence and outcomes of flank hernias, resulting mostly from traumatic
injuries and incisions, are also a mixture of open and laparoscopic cases. Although not true
hernias, there are data related to the incidence of flank bulging after retroperitoneal incisions
and possible mechanism of this occurrence [Carbonell et al., 2005a]. Chatterjee and
coworkers [2004] evaluated 70 patients undergoing flank incisions for nephrectomy and
reported 49% of patients complaining of flank bulging. Gardner et al. [1994] performed an
analysis of flank bulge using neurophysiologic testing, cadaver dissection, and clinical data
on 63 patients. They reported an 11% incidence of flank bulge and showed this phenomenon
is related to intercostal nerve injury with subsequent paralysis of the abdominal wall
musculature. There are two reports on the use of bone anchor fixation for atypical hernias.
Carbonell and colleagues [2005b] reported on 10 patients undergoing open retromuscular
repair of lumbar hernias with the use of bone anchors for fixation. They reported excellent
outcomes with a mean hospital length of stay of 5.2 days, no postoperative complications, and
at a mean follow-up of 40 months, without recurrences. Yee et al. [2008] evaluated bone
anchor fixation in laparoscopic repairs in 30 patients, with 17 suprapubic and 13 lateral. They
reported an average length of hospital stay of 5.2 days, 23.3% complication rate, 3.3%
mortality rate, and a 6.7% recurrence rate at a mean follow-up of 13.2 months. In general,
these series report on standard techniques of the open and laparoscopic repair of the flank
hernia adhering to the principles of wide overlap of mesh with appropriate fixation. However,
due to patient factors, slight differences in techniques, and use of mesh, there is some
variability in the outcomes.
SUMMARY
Aytpical hernias or hernias located at the abdominal borders can be extremely
challenging to repair. Thorough knowledge of anatomy, appropriate preoperative planning,
and reliance on the principles of hernia repair including wide mesh overlap and fixation will
ensure successful outcomes. Many options for repair including technique and mesh choice are
available for the surgeon. The hernia surgeon should be well versed in the open and
William W. Hope, William F. Powers and W. Borden Hooks
224
laparoscopic approaches and apply them based on the individual clinical presentation.
Currently, long term outcomes related to suprapubic, subxiphoid, and lateral hernia repairs
are somewhat limited; however, open and laparoscopic repairs employing wide mesh overlap
and adequate fixation have acceptable outcomes and recurrence rates. Future research will
likely focus on comparative studies based on patient factors, techniques and meshes use, and
cost utilization to help surgeons choose the appropriate repairs for individual patients.
REFERENCES
Ahmad, G., O'Flynn, H., Duffy, J. M., Phillips, K. & Watson, A. (2012). Laparoscopic entry
techniques. Cochrane Database Syst. Rev., 2, CD006583.
Ali, A. A. & Malata, C. M. (2012). The use of Mitek bone anchors for synthetic mesh fixation
to repair recalcitrant abdominal hernias. Ann. Plast. Surg, 69, 59-63.
Bachman, S. & Ramshaw, B. (2008). Prosthetic material in ventral hernia repair: how do I
choose? Surg. Clin. North Am, 88, 101-112.
Barner, H. B. (1987). A technical modification of median sternotomy to eliminate subxiphoid
incisional hernias. Arch. Surg, 122, 843.
Beck, W. C., Holzman, M. D., Sharp, K. W., Nealon, W. H., Dupont, W. D. & Poulose, B. K.
(2013). Comparative effectiveness of dynamic abdominal sonography for hernia vs
computed tomography in the diagnosis of incisional hernia. J. Am. Coll. Surg, 216,
447-453.
Binnebosel, M., Rosch, R., Junge, K., Flanagan, T. C., Schwab, R. & Schumpelick, V.
(2007). Biomechanical analyses of overlap and mesh dislocation in an incisional hernia
model in vitro. Surgery, 142, 365-371.
Burger, J. W., Luijendijk, R. W., Hop, W. C., Halm, J. A., Verdaasdonk, E. G. & Jeekel, J.
(2004). Long-term follow-up of a randomized controlled trial of suture versus mesh
repair of incisional hernia. Ann. Surg, 240, 578-583.
Byrd, J. F., Agee, N., Swan, R. Z., Lau, K. N., Heath, J. J., McKillop, I. H., Sindram, D.,
Martinie, J. B. & Iannitti, D. A. (2011). Evaluation of absorbable and permanent mesh
fixation devices: adhesion formation and mechanical strength. Hernia, 15, 553-558.
Carbonell, A. M., Kercher, K. W., Matthews, B. D., Sing, R. F., Cobb, W. S. & Heniford, B.
T. (2005a). The laparoscopic repair of suprapubic ventral hernias. Surg, Endosc. 19,
174-177.
Carbonell, A. M., Kercher, K. W., Sigmon, L., Matthews, B. D., Sing, R. F., Kneisl, J. S. &
Heniford, B. T. (2005b). A novel technique of lumbar hernia repair using bone anchor
fixation. Hernia, 9, 22-25.
Chatterjee, S., Nam, R., Fleshner, N. & Klotz, L. (2004). Permanent flank bulge is a
consequence of flank incision for radical nephrectomy in one half of patients. Urol.
Oncol, 22, 36-39.
Conze, J., Binnebosel, M., Junge, K. & Schumpelick, V. (2010). [Incisional hernia - how do I
do it? Standard surgical approach]. Chirurg, 81, 192-200.
Finan, K. R., Vick, C. C., Kiefe, C. I., Neumayer, L. & Hawn, M. T. (2005). Predictors of
wound infection in ventral hernia repair. Am. J. Surg, 190, 676-681.
The Surgical Management of Atypical Hernias
225
Frantzides, C. T. & Welle, S. N. (2012). Cardiac tamponade as a life-threatening complication
in hernia repair. Surgery, 152, 133-135.
Gardner, G. P., Josephs, L. G., Rosca, M., Rich, J., Woodson, J. & Menzoian, J. O. (1994).
The retroperitoneal incision. An evaluation of postoperative flank 'bulge'. Arch. Surg,
129, 753-756.
Heniford, B. T., Park, A., Ramshaw, B. J. & Voeller, G. (2003). Laparoscopic repair of
ventral hernias: nine years' experience with 850 consecutive hernias. Ann. Surg, 238,
391-399.
Hope, W. W., Griner, D., Adams, A., Hooks, W. B. & Clancy, T. V. (2012). Use and
indications of human acellular dermis in ventral hernia repair at a community hospital.
Plast. Surg. Int, 2012, 918345.
Jenkins, E. D., Yom, V. H., Melman, L., Pierce, R. A., Schuessler, R. B., Frisella, M. M.,
Eagon, J., Brunt, L. & Matthews, B. D. (2010). Clinical predictors of operative
complexity in laparoscopic ventral hernia repair: a prospective study. Surg. Endosc, 24,
1872-1877.
Kim, H. S., Kim, K. B., Hwang, H. Y., Chang, H. W. & Park, K. J. (2012). Subxiphoid
incisional hernia development after coronary artery bypass grafting. Korean J. Thorac.
Cardiovasc. Surg, 45, 161-165.
LeBlanc, K. A. (2007). Laparoscopic incisional hernia repair: are transfascial sutures
necessary? A review of the literature. Surg. Endosc, 21, 508-513.
Luijendijk, R. W., Hop, W. C., van den Tol, M. P., de Lange, D. C., Braaksma, M. M.,
IJzermans, J. N., Boelhouwer, R. U., de Vries, B. C., Salu, M. K., Wereldsma, J. C.,
Bruijninckx, C. M. & Jeekel, J. (2000). A comparison of suture repair with mesh repair
for incisional hernia. N. Engl. J. Med, 343, 392-398.
Mackey, R. A., Brody, F. J., Berber, E., Chand, B. & Henderson, J. M. (2005). Subxiphoid
incisional hernias after median sternotomy. J. Am. Coll. Surg, 201, 71-76.
Morales-Conde, S., Cadet, H., Cano, A., Bustos, M., Martin, J. & Morales-Mendez, S.
(2005). Laparoscopic ventral hernia repair without sutures--double crown technique: our
experience after 140 cases with a mean follow-up of 40 months. Int. Surg., 90(3
Suppl),S56-62.
Muysoms, F., Vander Mijnsbrugge, G., Pletinckx, P., Boldo, E., Jacobs, I., Michiels, M. &
Ceulemans, R. (2013). Randomized clinical trial of mesh fixation with "double crown"
versus "sutures and tackers" in laparoscopic ventral hernia repair. Hernia, Apr 2, Epub
2013/04/03.
Novitsky, Y. W., Elliott, H. L., Orenstein, S. B. & Rosen, M. J. (2012). Transversus
abdominis muscle release: a novel approach to posterior component separation during
complex abdominal wall reconstruction. Am. J. Surg, 204, 709-716.
Novitsky, Y. W., Harrell, A. G., Hope, W. W., Kercher, K. W. & Heniford, B. T. (2007).
Meshes in hernia repair. Surg. Technol. Int., 16, 123-127.
Novitsky, Y. W., Porter, J. R., Rucho, Z. C., Getz, S. B., Pratt, B. L., Kercher, K. W. &
Heniford, B. T. (2006). Open preperitoneal retrofascial mesh repair for multiply recurrent
ventral incisional hernias. J. Am. Coll. Surg, 203, 283-289.
O'Dwyer, P. J. & Courtney, C. A. (2003). Factors involved in abdominal wall closure and
subsequent incisional hernia. Surgeon, 1, 17-22.
William W. Hope, William F. Powers and W. Borden Hooks
226
Palanivelu, C., Rangarajan, M., Parthasarathi, R., Madankumar, M. V. & Senthilkumar, K.
(2008). Laparoscopic repair of suprapubic incisional hernias: suturing and intraperitoneal
composite mesh onlay. A retrospective study. Hernia, 12, 251-256.
Reynvoet, E., Berrevoet, F., De Somer, F., Vercauteren, G., Vanoverbeke, I., Chiers, K. &
Troisi, R. (2012). Tensile strength testing for resorbable mesh fixation systems in
laparoscopic ventral hernia repair. Surg. Endosc, 26, 2513-2520.
Rosen, M. J. (2010). Biologic mesh for abdominal wall reconstruction: a critical appraisal.
Am Surg, 76, 1-6.
Schumpelick, V., Klingem U., Junge, K. & Stumpf, M. (2004). Incisional abdominal hernia:
the open mesh repair. Langenbecks Arch. Surg, 389, 1-5.
Sharma, A., Dey, A., Khullar, R., Soni, V., Baijal, M. & Chowbey, P. K. (2011).
Laparoscopic repair of suprapubic hernias: transabdominal partial extraperitoneal (TAPE)
technique. Surg. Endosc, 25, 2147-2152.
Shell, D.H., de la Torre, J., Andrades, P. & Vasconez, L. O. (2008). Open repair of ventral
incisional hernias. Surg. Clin. North Am, 88, 61-83.
Swenson, B, R., Camp, T. R., Mulloy, D. P. & Sawyer, R. G. (2008). Antimicrobial-
impregnated surgical incise drapes in the prevention of mesh infection after ventral hernia
repair. Surg. Infect. (Larchmt), 9, 23-32.
van 't Riet, M., Steyerberg, E. W., Nellensteyn, J., Bonjer, H. J. & Jeekel, J. (2002). Meta-
analysis of techniques for closure of midline abdominal incisions. Br. J. Surg, 89, 1350-
1356.
Varnell, B., Bachman, S., Quick, J., Vitamvas, M., Ramshaw, B. & Oleynikov, D. (2008).
Morbidity associated with laparoscopic repair of suprapubic hernias. Am. J. Surg, 196,
983-987.
Vilos, G. A., Ternamian, A., Dempster, J. & Laberge, P. Y. The Society of Obstetricans and
Gynaecologists of Canada. (2007). Laparoscopic entry: a review of techniques,
technologies, and complications. J. Obstet. Gynaecol. Can, 29, 433-465.
Voeller, G. R., Ramshaw, B., Park, A. E. & Heniford, B. T. (1999). Incisional hernia. J. Am.
Coll. Surg, 189, 635-637.
Yee, J. A., Harold, K. L., Cobb, W. S. & Carbonell, A. M. (2008). Bone anchor mesh fixation
for complex laparoscopic ventral hernia repair. Surg. Innov, 15, 292-296.
In: Hernias ISBN: 978-1-62948-441-9
Editor: Mark A. Suckow © 2014 Nova Science Publishers, Inc.
Chapter 15
SMALL INTESTINAL SUBMUCOSA BIOMATERIAL
FOR THE REPAIR OF AN ABDOMINAL HERNIA IN A
DIABETIC RAT MODEL
Mark A. Suckow
1*
, William R. Wolter
1
, Susan M. LaBadie-Suckow
1
and Chad Johnson
2
1
University of Notre Dame, Notre Dame IN, US
2
Cook Biotech, Inc., West Lafayette, IN 47906
ABSTRACT
Repair of hernia in diabetic patients is complicated by impaired wound healing
ability of the patient. Though a variety of materials are used for herniorraphy, repair with
biomaterials is often preferred due to incorporation of the implant into host tissue.
However, incorporation of the implanted material can be compromised by the impaired
healing response, thus potentially leading to a weak repair. Porcine small intestinal
submucosa (SIS) is a naturally-derived biomaterial used in a wide range of clinical
applications, including repair of hernia. We describe studies designed to evaluate the
ability of SIS to incorporate into host tissue when used to repair ventral abdominal hernia
in a rat model of diabetes mellitus. Zucker diabetic rats underwent surgical hernia
creation followed by implantation of a SIS patch to repair the defect. Though the diabetic
nature of the rats led to significant issues with wound healing, histological evaluation
showed that the SIS underwent robust remodeling into fibrovascular tissue within 28 days
of implantation. Further, mechanical strength testing showed that the SIS had remodeled
into appropriately strong tissue. Small intestinal submucosa is biocompatible, is readily
remodeled into strong tissue and represents an outstanding material for use in repair of
hernia in diabetic individuals.
Keywords: Ventral hernia, small intestinal submucosa, biomaterial, diabetic
*
Corresponding author: Freimann Life Science Center, University of Notre Dame, Notre Dame, IN 46556 USA,
Email: Suckow.1@nd.edu.
Mark A. Suckow, William R. Wolter, Susan M. LaBadie-Suckow et al.
228
INTRODUCTION
Abdominal wall hernia is a commonly encountered clinical issue which may occur as the
result of congenital defect, traumatic injury, or failed closure of surgical wounds involving
the abdominal wall. Repair commonly involves using an implant to reinforce the abdominal
wall, with a reduced rate of recurrence noted in patients treated with an implant compared to
those in which the abdominal wall is simply closed with suture [Poussier et al., 2013].
Both synthetic and natural materials are used for hernia repair. Many synthetic materials
are typically non-absorbable and include polypropylene, polyethylene terephthalate polyester,
and expanded polytetrafluoroethylene, while other synthetic implants combine one of the
non-absorbable materials with an absorbable polymer such as polygalactine [Poussier, 2013].
Generally, implants made from synthetic materials are in mesh or woven form. In contrast,
natural material implants are generally derived from either animal or human cadaveric
sources. Natural materials used for hernia repair are typically rich in collagen and act as a
scaffold for ingrowth and integration of host tissue.
Porcine small intestinal submucosa (SIS) is a natural biomaterial that has been used for a
wide variety of tissue repair indications, including repair of hernia [Helton et al., 2005;
Trevino et al., 2006; Ginting et al., 2010]. SIS is rapidly incorporated into host tissue and has
been found to be generally resistant to infection and so the material has particular utility in
infected fields [Clarke et al., 1996; Sarikaya et al., 2002].
Impaired healing following surgery is a hallmark of diabetes, and is believed due to
microangiopathy, hindered collagen production, and impaired immune responses associated
with hyperglycemia [Ljungqvist, et al., 2005]. The delay in healing may result in increased
susceptibility of the patient to post-operative infection, as well as wound dehiscence. Clearly,
the diabetic patient is at risk following surgery, and strategies for improved healing following
repair of abdominal wall defects are needed. In this regard, SIS may be of particular utility.
EXPERIMENTAL APPROACH
In establishing the ability of SIS implant to successfully reinforce the abdominal wall
following incisional hernia in diabetic individuals, it is critical to use an appropriate animal
model. In this regard, there exist a variety of models which use rodents or swine, and which
involve animals genetically predisposed to diabetes or those which undergo chemical or
dietary induction of the disease [Shafrir, 2007].
The Zucker diabetic Sprague-Dawley (ZDSD) rat is a novel animal model of adult-onset
diabetes mellitus rat. Onset of diabetes in the ZDSD rat is characterized by rapid weight gain,
insulin resistance prior to hyperglycemia, and decreased insulin levels once diabetes has
developed [Peterson, 2007]. Through selective inbreeding ZDSD rats were developed that
have an obese phenotype and the potential to become hyperglycemic between 15 and 21
weeks of age. ZDSD rats do not possess any leptin or leptin receptor defects and tend to
deteriorate physically in response to chronic metabolic dysfunction. The author’s laboratory
has anecdotally noted the ZDSD to have an impaired wound healing response.
To investigate the efficacy of SIS implant with respect to incisional hernia repair, four-
month old male ZDSD rats (Preclinomics, Inc., Indianapolis, IN) documented to be free of
Small Intestinal Submucosa Biomaterial …
229
common infectious pathogens were used. All studies were approved by the Institutional
Animal Care and Use Committee. Rats were maintained in solid-bottom polycarbonate cages
containing abundant hardwood chip bedding. They were allowed ad libitum access to fresh
water. Diabetes was induced in a cohort of ZDSD rats by providing LabDiet 5SCA (PMI
Nutrition, International, St. Louis, MO) at the time of weaning, followed by LabDiet 5008 at
17 weeks of age. To confirm diabetes at 21 weeks of age, blood glucose was measured using
a handheld Truetrack® glucometer (Nipro Diagnostics, Fort Lauderdale, FL). Blood to be
assayed for glucose levels was sampled from the tail vein at these same time points. As a
criterium for diabetes, rats with blood glucose levels exceeding 300 mg/dL were to be
considered diabetic and those with levels below 180 mg/dL were to be considered non-
diabetic. All ZDSD rats on the diabetes induction diet were confirmed to be diabetic with
blood glucose levels ranging from 350 to >600 mg/dL.
4-layer (4LL) SIS (Cook Biotech, Inc., West Lafayette, IN) SIS was prepared by
processing porcine intestine as a raw material, into an acellular, multilaminar medical-grade
material (Figure 1) that serves as a bioscaffold for in-growth of, and subsequent incorporation
into, normal, repaired tissue. Sheets of the 4LL SIS material were cut into 2 cm x 2 cm
squares using a template form. The SIS samples were subsequently sterilized using low
temperature ethylene oxide. In dry form, the material is stable at room temperature for an
extended period of time. 4LL SIS grafts were rehydrated in a normal saline solution for at
least 10 minutes immediately prior to implantation.
Following preparation for aseptic surgery, 16 rats were anesthetized using inhaled
isoflurane delivered via a precision vaporizer. An approximately 3-4 cm vertical incision was
made along the ventral midline down to the level of the abdominal musculature. An
approximately 2 cm diameter, full thickness defect was made in the abdominal wall centered
around the linea alba, and the sample graft was anchored in an overlay position with eight
non-absorbable 4-0 silk sutures (one in each corner and one in the middle of each graft edge).
The skin was closed with staples and the rat recovered from anesthesia, with 1 ml of sterile
saline given subcutaneously and 2 mg/kg of the analgesic, butorphanol tartarate was
administered subcutaneously initially after surgery and again four hours. Rats were
subsequently returned to their cages and observed for the duration of the study. The diabetic
nature of the rats led to significant issues with wound healing following surgery. Specifically,
many rats experienced dehiscence of surgical skin wounds, requiring the animals to be
anesthetized and undergo wound cleaning and re-stapling.
One month following surgery, the rats were euthanized via carbon dioxide narcosis and
the samples removed for analysis. At the time of euthanasia, the gross appearance of the
implant for tissue incorporation was noted, as was the presence or absence of adhesion to the
underlying viscera. At explant, a dog-bone shaped sample with a test width of 5mm was cut
using a die-press, packaged into a small plastic sample bag, and placed on ice prior to
mechanical testing. A remaining piece was fixed in 10% neutral buffered formalin, embedded
in paraffin, sectioned and stained with hematoxylin and eosin. Samples were subjectively
evaluated for evidence of host tissue incorporation.
Mechanical testing was performed on the samples within 12 hours of explant. Dog-bone
shaped samples were placed into clamps on an Instron tension tester (Instron, Inc., Norwood,
MA). Samples were deformed at a constant rate (100 mm/min) with the force recorded until
breakage. The ultimate tensile force (UTF) was determined as the highest force attained prior
to sample breakage.
Mark A. Suckow, William R. Wolter, Susan M. LaBadie-Suckow et al.
230
Figure 1. SEM image (100x magnification) of a cross-section of 4LL SIS. The SIS material consists
primarily of laminar sheets of collagen intermixed with additional ECM components. The open, porous
nature of SIS allows for fast cellular infiltration and tissue integration.
Gross examination of implants at the time of euthanasia determined that six out of 16 rats
(37.5%) had minor adhesions to pleural surfaces. There was no evidence of infection or
abscessation in any of the rats.
The mean UTF was determined to be 5.96 ± 2.62 N. This result compares favorably with
studies, using samples harvested from humans, which demonstrated average ultimate tensile
force of 7.5 N for the linea alba [Förstemann et al., 2011]. Because there is no published data
for tensile strength of the abdominal wall in diabetic individuals, we believe our results
suggest the likelihood of a very favorable outcome for diabetic patients undergoing repair of
abdominal wall hernia using SIS.
Examination of fixed tissue specimens using light microscopy demonstrated a robust
fibrovascular response characterized by numerous fibroblasts, abundant collagen, and
neovascularization (Figures 2 and 3). The implanted material had completely been
incorporated into host tissue with no remnants of implant evident. This response is similar to
that observed following implantation of SIS into normoglycemic subjects [Suckow, et al.,
2005; Suckow, et al., 2010], and indicates that even in diabetic individuals implanted SIS
serves as an effective scaffold for tissue ingrowth.
The influx of fibroblasts into the hernia repair site, as well as the strong angiogenic
response both signal an active and ongoing incorporation process. Because the SIS is a
biomaterial, the body does not tolerate it in a static manner, but rather embraces the scaffold it
provides. Within a relatively short period of time, the implanted material has been replaced
with host tissue.
All in all, the samples performed well, attesting to the ability of SIS to remodel under
challenging conditions. The implanted material was incorporated into the surrounding tissue
by ingrowth of fibrocollagenous tissue and blood vessels. This is in contrast to synthetic
permanent meshes which do not undergo incorporation into host tissue and are associated
with adverse sequelae such as erosion into bowel when placed intraperitoneally. Further,
permanent synthetic meshes are prone to bacterial colonization, and the subsequent infection
of host tissue typically requires surgical removal of the implant and risk of recurrent hernia
[Voyles et al., 1981]. In a rat model, biological implants were demonstrated to inhibit
bacterial growth, while synthetic material implants lacked the ability to do so [Harth et al.,
2011].