Objectives: To evaluate the efficacy of a cellular porcine small intestine submucosa in the repair of chronic tympanic membrane perforations.

1. Tympanic Membrane Perforation Repair with
Acellular Porcine Submucosa
Jeffrey H. Spiegel and Joshua L. Kessler
Department of Otolaryngology–Head and Neck Surgery, Boston University School of Medicine,
Boston, Massachusetts, U.S.A.
Objectives: To evaluate the efficacy of acellular porcine small
intestine submucosa in the repair of chronic tympanic membrane
perforations. Although tympanoplasty with autologous tempo-
ralis fascia and cartilage is common practice in the repair of
chronic tympanic membrane perforations, these materials are
associated with increased operative time and have variable
availability and quality in individual patients. Recently, new
materials for tympanoplasty have been explored, including
acellular human dermis. Small intestine submucosa (Surgisis)
is an inexpensive and readily available alternative to autol-
ogous and cadaveric grafts. In this study, we examined the use
of small intestine submucosa in the repair of chronic tympanic
membrane perforations in a chinchilla model.
Study Design: Prospective pilot study using 10 adult
chinchillas.
Methods: Chronic tympanic membrane perforations were
created in 10 adult chinchillas for a total of 20 perforations.
Each animal underwent observation in one ear and repair with
either autologous cartilage or small intestine submucosa in the
opposite ear with Type I tympanoplasty.
Results: A total of 20 chronic membrane perforations were
created, with zero healing spontaneously after 8 weeks. In
tympanoplasties performed in five chinchillas with small
intestine submucosa, five of five (100%) remained healed 6
weeks postoperatively, whereas three of five (60%) remained
healed with cartilage repair. Histologic analysis was per-
formed in both successful cartilage and small intestine sub-
mucosa repairs.
Conclusion: These results suggest that small intestine sub-
mucosa is a viable alternative to autologous and cadaveric
grafts in tympanoplasty. A larger randomized study in humans
is indicated to evaluate this material in clinical practice. Key
Words: Chinchilla—Surgisis—Tympanoplasty—Xenograft.
Otol Neurotol 26:563–566, 2005.
Chronic tympanic membrane (TM) perforation is a
common clinical entity in the otolaryngologist’s prac-
tice. It may lead to recurrent or chronic infection and
conductive hearing loss. Perforations may arise from
trauma, chronic or acute middle ear infections, or place-
ment of ventilation tubes. Most acute TM perforations
heal spontaneously; however, a chronic perforation may
ensue as a result of failure of epithelial growth across the
perforation. When a perforation persists, surgical repair
in the form of myringoplasty or tympanoplasty is often
indicated.
Many materials have been used in the history of TM
repair, including full-thickness or partial-thickness skin
grafts, vein grafts, sclera, perichondrium, temporalis fascia,
cartilage inlay, fat, and various papers including cig-
arette and rice paper (1,2). Recently, acellular human
dermis (AlloDerm; LifeCell, Inc., The Woodlands, TX,
U.S.A.) has shown promise in the repair of chronic TM
perforations in both animal studies and human case
reports (3–6).
Acellular porcine small intestine submucosa (SIS) is
an acellular biomaterial that functions as scaffolding for
tissue repair and remodeling. SIS (Surgisis; Cook, Inc.,
Bloomington, IN, U.S.A.) has been used as a vascular
graft; for skin graft donor sites; to cover and assist
healing in complex wounds; and for the repair of defects
in the bladder, dura, and abdominal wall (7–9). In all
cases, the material has proven to be well tolerated and
a useful product to effect successful soft-tissue coverage
or bolstering.
SIS may offer several advantages over both autografts
and human acellular dermis in the repair of tympanic
membrane perforations. Temporalis fascia is presently
the most commonly used autograft in tympanoplasty
because it may be harvested from the same surgical site
and has a success rate of 88 to 95% (2). The disadvan-
tages of autografting include donor-site morbidity, in-
creased intraoperative time, the microsurgical skills of
the surgeon, and the variability of the quality of autograft
Address correspondence and reprint requests to Jeffrey H. Spiegel,
M.D., F.A.C.S., Department of Otolaryngology–Head and Neck Surgery,
Boston University School of Medicine, 88 East Newton Street, D-6,
Boston, MA, U.S.A.; E-mail: jeffrey.spiegel@bmc.org
An unrestricted educational and research grant was received from
Cook, Inc.
Otology & Neurotology
26:563–566 Ó 2005, Otology & Neurotology, Inc.
563

2. material among patients. For revision cases, temporalis
fascia may not be available and a second incision must
be made for harvesting. The potential advantages of SIS
over autografting include its ready availability, ease of
use, decreased intraoperative time, and uniform thickness.
Acellular human dermis has been studied recently in
tympanoplasty and appears to be effective (3–6). The use
of cadaver tissue is limited by the shortage of suitable
human donors (i.e., those with a low risk of transmission
of infection). Xenografting offers a reasonable alter-
native to human cadaver harvesting in that there is a
plethora of available tissue that is unlikely to pose an
infectious risk. As a result, xenograft materials tend to
be much less expensive and more readily available than
cadaveric tissue while posing less of a risk of transmis-
sion of an infectious agent. The utility of xenografting
has been proven time and time again, with the most
obvious example in the use of porcine xenografts for
cardiac valve replacements. Although there has been
anecdotal evidence regarding the use of SIS in office
myringoplasty, to our knowledge there have been no
animal studies exploring the histology and efficacy of
the material. In light of these factors, we conducted an
animal-based pilot study to explore the efficacy of SIS in
the repair of chronic tympanic membrane perforations.
MATERIALS AND METHODS
Ten adult chinchillas (Moulton Chinchilla Ranch, Rochester,
MN, U.S.A.) were included in the study, each weighing from
350 to 500 g.
Creation of Perforations
Each animal was anesthetized with a solution of 30 mg/kg
ketamine and 5 mg/kg xylazine injected intraperitoneally (i.p.).
Under microscopic vision, a 3-mm otologic speculum was used
to expose the TM. A myringotomy knife was used to create
a perforation in the anterior half of the TM and a right-angled
hook was used to fold the free edges of the drum medially.
This is a modification of the method originally described by
Amoils et al. (11) to create chronic TM perforations in the
chinchilla. Each animal was examined daily for outward signs
of infection; however, none required topical or enteral anti-
biotics. After 2 weeks and then every 3 weeks for a total of
8 weeks, each animal was examined under anesthesia for signs
of healing; however, no perforation healed spontaneously.
Tympanoplasties
All 10 animals were selected randomly to undergo
tympanoplasty with autologous cartilage or with SIS. Once
divided into the two arms, tympanoplasties were randomly
conducted in the left or right ear. The opposite ear was left
unrepaired as a control. Each animal was anesthetized with
ketamine and xylazine as above. Under the operating micro-
scope, the edges of the perforation were roughened with a
Rosen needle and the middle ear space packed with absorbable
gelatin squares (Gelfoam; The Upjohn Co., Kalamazoo, MI,
U.S.A.) up to the rim of the perforation. In those animals that
underwent repair with SIS, a small rectangular piece of SIS
(approximately 0.1 mm thick) was placed medial to the drum
and over the gelatin sponge in a punch-through underlay
fashion. In the cartilage repair group, a small incision was
created in the medial portion of the auricle, and mucoper-
ichondrial flaps raised on both sides of the cartilage, which was
then excised. The cartilage was then placed medial to the drum
in the same fashion as the SIS repairs. The skin was closed
with a single 5-0 plain gut suture. Cartilage was selected for
comparison because of the ability to harvest it locally and
without the increased pain of a leg incision as would be
necessary to obtain good fascia. In addition, cartilage is a more
durable and substantial material that has proven to be effective
in tympanoplasty. Although not expected to repair a TM with
the mobility of a fascia graft repair, cartilage is expected to
have a high success rate, as it is less likely to have the edges
roll up or perforate. In all repairs, no gelatin sponge or other
material was placed in the external auditory canal. Animals
were checked daily for outward signs of infection.
Evaluation of Repair
After 6 weeks, each animal was again anesthetized with i.p.
xylazine and ketamine and each ear was examined under
the operating microscope. Each ear was recorded as healed
or not healed. Representative drums recorded as healed were
harvested via a postauricular incision and dissection with an
otologic drill and fixed in formalin for histologic analysis after
the animal was killed with 1 ml of 26% sodium pentobarbital
injected i.p. These specimens were later mounted in paraffin,
stained with hematoxylin and eosin, and examined by a staff
pathologist. Six of 10 animals were adopted out to private homes.
RESULTS
Evaluation of Creating and Repairing
Chronic Perforations
Of the 20 ears in which chronic perforations were
created, all (100%) remained perforated after 8 weeks,
with no evidence of infection or significant healing. Of
those 10 that were left unrepaired as controls, 100%
remained perforated after the additional 6-week course
it took to complete the study. All five of five perfora-
tions (100%) repaired with SIS were completely healed
6 weeks after initial repair, whereas three of five per-
forations (60%) repaired with cartilage were completely
healed. Of those two perforations that persisted in the
cartilage repair group, both had large perforations with
little evidence of healing. This was a pilot study to assess
the ability of SIS to be used for TM repair and so
qualitative observations were desired and expected; as
a result, in this trial, statistical calculations are not used.
Gross and Histologic Analysis
On gross inspection of both groups of successfully
repaired drums, there was complete closure of the per-
foration with neovascularization. On the drums repaired
with SIS, there appeared to be a translucent appearance
to the repaired surface, with evidence of mild calcifica-
tion (Fig. 1). In contrast, those drums repaired with
cartilage demonstrated complete opacification in the area
where the graft was placed. This likely represented the
persistence of cartilage medial to the repaired drum. In
those areas not repaired, the drum appeared normal in all
specimens.
564 J. H. SPIEGEL AND J. L. KESSLER
Otology & Neurotology, Vol. 26, No. 4, 2005

3. Histologic analysis was conducted on representative
drums repaired with both cartilage and SIS (Figs. 2 and 3).
The drum repaired with cartilage revealed a monomeric
layer composed of squamous epithelium and the carti-
lage graft situated medially to the repaired drum. There
were small areas of repair where a bilaminar repair was
present consisting of epithelium and mucosa, both lat-
eral to the cartilage. There was evidence of mild inflam-
mation and areas of calcification within the cartilage.
SIS-repaired drum sections demonstrated a trilaminar
membrane composed of squamous epithelium, graft
material within the drum in place of a fibrous layer, and
a medial cuboidal mucosa. Compared with the cartilage
graft, there was more inflammation present.
DISCUSSION
Multiple studies have demonstrated the results of
various materials in the repair of tympanic membrane
perforations (1–6,10). The normal anatomy of the human
and chinchilla TM consists of a thin lateral squamous
epithelium, a middle fibrous layer, and a medial cuboidal
mucosal layer. In a chinchilla model of chronic tym-
panic membrane perforations, Amoils et al. (11) ex-
plored the histologic results of creating perforations in
the tympanic membrane. The drums that maintained
a chronic perforation with no evidence of healing dis-
played marginal strands of dense connective tissue cov-
ered with a thin layer of squamous epithelium, and at the
edge of the perforation the squamous layer extended
medially to contact the medial mucosal surface. Both the
squamous layer and the fibrous layer demonstrated hy-
perplasia and hypertrophy. In those drums that demon-
strated spontaneous healing, a thin layer of squamous
epithelium covering the original site of the perforation
was present.
A recent study comparing rice paper to acellular
human dermis (AlloDerm) in the repair of chronic per-
forations in the chinchilla demonstrated the formation
of a bilaminar membrane in perforations repaired with
rice paper and a trilaminar membrane in the AlloDerm
repair group (5). The trilaminar repair was felt to signify
a more desirable result. This study yielded a successful
repair in 78% of drums repaired with AlloDerm using a
medial graft technique and 66% repaired with rice paper
in an onlay myringoplasty technique. Another signifi-
cant finding revealed a much larger average thickness
of drums repaired with AlloDerm compared with normal
drum thickness and those repaired with rice paper. The
clinical significance of this finding is unknown.
Our study explored the use of acellular porcine small
intestine submucosa (Surgisis) in the repair of chronic
FIG. 1. In vivo telescopic photograph of a healed TM repair
with porcine small intestine submucosa demonstrating a trans-
lucent repaired site with surrounding calcification and minimal
scarring.
FIG. 2. Cartilage-grafted TM photomicrograph showing cartilage
medial to a monomeric squamous epithelium (arrowhead). Note
the adjacent normal trilaminar TM (hematoxylin and eosin stain;
original magnification, 3100).
FIG. 3. SIS-grafted TM photomicrograph demonstrating trilami-
nar TM with incorporated graft material (filled arrowhead marks
the junction of normal and grafted TM) and moderate inflamma-
tion. Open arrowhead shows out-pouching of drum from histologic
processing (hematoxylin and eosin stain; original magnification,
3100).
TYMPANIC PERFORATION REPAIR WITH SUBMUCOSA 565
Otology & Neurotology, Vol. 26, No. 4, 2005

4. membrane perforations compared with controls of no
repair and also with the use of endogenous cartilage
using the same technique of punch-through transcanal
tympanoplasty with the graft placed medial to the drum.
We found an excellent repair rate compared with con-
trols. Our results were evaluated qualitatively rather than
statistically in this pilot study to avoid subjecting the
large number of animals necessary for statistical power
to surgery until the method was tested in a smaller pop-
ulation. Nonetheless, the results strongly suggest that
SIS is as effective if not superior to cartilage in the repair
of chronic TM perforations. In all TMs repaired with
SIS, an excellent result was obtained. Given that none of
our nonrepaired controls healed spontaneously, it is also
suggested that SIS is a viable candidate for use in
tympanoplasty. On the basis of power studies before the
beginning of our study, we would have required the use
of over 100 animals to prove that SIS is, in fact,
statistically equal or superior to cartilage grafting.
The histologic analysis coincides with that of other
studies. We found in repair with SIS the creation of
a trilaminar membrane with the grafting material im-
bedded in the fibrous layer of the drum. This was located
between a lateral layer of squamous epithelium and
a medial layer of cuboidal mucosa. Interestingly, the
cartilage repairs revealed a predominantly monolaminar
membrane, with the cartilage evident medial to a squa-
mous layer. The middle fibrous layer was absent and
there were areas where mucosa was present in a
bilaminar membrane lateral to the cartilage. This
suggests that although the cartilage served as a conduit
for the migration of the healing drum, the SIS was
actually incorporated into the drum itself. It has been
suggested that the formation of a trilaminar repair is
superior to that of a dimeric or monomeric repair, in that
it represents a more durable drum and more closely
resembles the native drum.
Although there was evidence of inflammation present
in both types of repair, there was no evidence of
rejection of either the cartilage or the SIS. This was an
expected finding, as the cartilage was an autograft and
the SIS had been stripped of its antigenic properties
during its preparation.
CONCLUSIONS
The results of this pilot study suggest that SIS is
effective in the repair of chronic TM perforations. We
chose SIS as a material to explore in tympanoplasty
because it is characterized by many of the qualities
sought in grafting materials: it is readily available,
inexpensive, and easy to work with; it decreases the time
spent harvesting a native graft and requires no second
incision in transcanal procedures; it is not antigenic; and
it carries no risk of transmission of human disease.
These benefits suggest that SIS is an excellent choice for
graft material in myringoplasty and tympanoplasty.
Acknowledgment: The authors would like to thank
Dr. Charles Allam for help with the preparation and inter-
pretation of the histologic slides.
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