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Biophysical and Microscopic Analysis of Homologous Dermal and Fascial Materials for Facial Aesthetic and Reconstructive Uses
Anthony P. Sclafani, MD;
Steven A. McCormick, MD;
Rubina Cocker, MD
Arch Facial Plast Surg. 2002;4:164-171.
ABSTRACT
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Objectives To evaluate the microscopic structure and physical properties of homologous
tissue grafts commonly used in aesthetic and reconstructive facial plastic
surgery in order to determine specific properties of these materials that
may affect their performance in vivo.
Methods Two decellularized dermal materials (AlloDerm and DuraDerm) and 2 fascia
lata tissue grafts (Tutoplast and cadaveric fascia lata) were examined by
light microscopy (hematoxylin-eosin and Movat staining) and scanning electron
microscopy. The physical properties of these materials were also examined
for thickness, maximum sustainable load, strain, conformability, and elasticity.
Results Significant differences in microscopic appearance existed between the
2 dermal materials and the 2 fascial materials. AlloDerm and Tutoplast fascia
lata retained architecture closer to that of untreated tissue than did DuraDerm
and cadaveric fascia lata, respectively. Tutoplast fascia lata and AlloDerm
were also stronger than cadaveric fascia lata and DuraDerm, respectively.
AlloDerm retained significantly more elasticity than DuraDerm.
Conclusions AlloDerm and Tutoplast fascia lata retain more natural architecture
and physical properties than do DuraDerm and cadaveric fascia lata, respectively.
These differences clearly show the effect of the specific processing of these
materials. The alteration in architecture and the degradation of the physical
properties of DuraDerm and cadaveric fascia lata may hinder the performance
of these grafts in vivo. Further studies on these materials in humans are
currently under way.
INTRODUCTION
A VARIETY of materials for soft tissue replacement are currently available,
running the gamut from freshly harvested autologous tissue to synthetic biomaterials.
Autologous cartilage is the optimal material for structural or volumetric
treatment in cartilaginous areas, such as the middle and lower nasal thirds.
However, replacement or augmentation of facial, dermal, or subcutaneous tissue
requires a more supple and pliant material than cartilage.
Many materials have been proposed for use as facial soft tissue fillers.
Autologous tissues such as dermis, fat, and fascia are well tolerated and
well incorporated into surrounding native tissue. There is no risk of viral
or prion transmission. However, they require a second operative site and additional
operative time for harvesting, and, to varying degrees, all undergo resorption.
Synthetic materials can easily be contoured to fit a particular defect and
are readily available in large sterile quantities. However, these materials,
if infected, frequently require removal. More commonly, they are generally
best suited for deep placement, as their physical qualities impart a distinctly
different feel when compared with surrounding tissues. Patients with synthetic
implants for treatment of deep nasolabial folds and lip augmentation may request
implant removal because of the chronically unnatural feel of the material
that may be present when placed in a subdermal plane.
Homologous materials, such as cadaveric irradiated or lyophilized fascia
lata or dura mater, or processed dermis offer the advantage of a readily available
human material for use. These materials can easily be shaped and used as human
tissue grafts for physical support in procedures such as slings for filler
materials or facial paralysis or congenital ptosis. These tissues are processed
to remove all donor cells and major histocompatibility antigens to limit the
graft-vs-host response. However, the theoretical risk of infectious disease
transmission exists.
These homologous materials are eventually incorporated or replaced by
new fibrous tissue and can supply significant tensile strength. The clinical
performance and histologic fate of these materials are to some degree affected
by the initial tensile strength and proteinaceous integrity. This study examines
the histologic and biophysical properties of 4 commonly used materials: 2
fascia lata–based materials and 2 dermis derivatives.
MATERIALS AND METHODS
MATERIAL PREPARATION
Dermis Derivatives
An acellular dermal graft, AlloDerm (LifeCell Corp, Branchburg, NJ),
and DuraDerm (Collagenesis, Inc, Beverly, Mass) are both derived from skin
obtained from tissue banks accredited by the American Association of Tissue
Banks and then sterilely processed. In each, the epidermis is removed and
the dermis is treated with detergents to remove the cellular elements. DuraDerm
is further treated with 3000- to 3900-rad (3- to 3.9-kGy) gamma irradiation.
The resultant acellular dermal mass is then freeze-dried to produce stable,
sterile materials with significant shelf lives. DuraDerm is identical to Dermaplant
(Collagenesis, Inc) in its processing and was used in this study because Dermaplant
had not yet become commercially available.
Fascia Lata Derivatives
Homologous fascia lata (Tutoplast; Tutogen Medical, Inc, Alachua, Fla)
is treated with a patented chemical process to remove all cells and is then
freeze-dried after irradiation. Cadaveric fascia lata (Community Tissue Services,
Ft Worth, Tex) is gamma-irradiated with cobalt 60 at 15 000 to 25 000
rad (15-25 kGy) for sterilization and subsequently freeze-dried.
RECONSTITUTION
All materials were processed per the manufacturers' or suppliers' recommendations
under sterile conditions before evaluation. AlloDerm sheets were rehydrated
in 2 separate baths (5 minutes each) of isotonic sodium chloride solution.
DuraDerm was rehydrated in a single isotonic sodium chloride solution bath
for 5 minutes. Tutoplast fascia lata was rehydrated in isotonic sodium chloride
solution for 10 minutes until soft. Cadaveric fascia lata was rehydrated in
isotonic sodium chloride solution for 30 minutes.
MICROSCOPY
All specimens were divided after rehydration into portions for micrometry,
light microscopy, and scanning and transmission electron microscopy. For evaluation
of material thickness, formalin-fixed specimens were mounted on glass slides
perpendicularly. Specimens were then examined under x4 magnification
and the material thickness was measured with an objective-mounted micrometer.
Specimens were batch-processed for hematoxylin-eosin, Movat pentachrome, and
anti–type IV collagen staining to ensure uniformity of staining. The
materials were sectioned at 5 µm.
ELECTRON MICROSCOPY
Each biomaterial sample was fixed in 4% glutaradehyde in cacodylate
buffer in phosphate-buffered saline. The samples were rinsed and dehydrated
in graded ethanols; they were then placed for 1 hour in 50% hexamethyldisilazane
(Electron Microscopy Sciences, Fort Washington, Pa) followed by 100% hexamethyldisilazane.
After vacuum air-drying, the specimens were sputter-coated with gold-palladium
alloy and examined in a scanning electron microscope (5-kV accelerating voltage)
(JEOL 6400; JEOL Ltd, Tokyo, Japan) at x5 to x20 magnification.
BIOPHYSICAL TESTING
Tissue samples of AlloDerm, DuraDerm, cadaveric fascia lata, and Tutoplast
fascia lata were obtained and rehydrated in room-temperature phosphate-buffered
saline as described. Strips of tissue measuring 1 x 4 cm were then cut
from each group. In the case of the fascia lata materials, where fiber orientation
could be determined, strips were cut along the long axis of fiber orientation.
Tensile Testing
The 10 x 40-mm pieces were cut down by means of a dumbbell-shaped
jig to a 3 x 15-mm test area with a 10 x 12.5-mm area on each
end for gripping. Sample pieces were measured for thickness by means of a
vernier micrometer (Mituyo Corp, Kyoto, Japan). Measurements were taken at
3 points along the test portion of tissue and averaged.
Samples were then placed into a tensile tester (Chatillon LRX; AMETEK
Test and Calibration Instruments Division, Largo, Fla) with the test portion
centered between the grips. A 0.5-N preload was applied to all samples. Samples
were then pulled to failure with the use of a 500-N load cell at a rate of
12.7 mm/min. All samples were noted to fail along the necked-down test portion
of the tissue.
Maximum load, maximum stress, and elastic modulus (in the range of 0-2
N) were calculated by means of Chatillon Dapmat software (AMETEK Test and
Calibration Instruments Division).
Three-Point Bend Load Testing
The tensile tester was used to calculate 3-point bend load. Rehydrated
pieces of each material measuring 10 x 40 mm were carefully centered
on a 15 x 45-mm piece of wax paper. Care was taken not to introduce
moisture to the backside of the tissue-tissue combination. Samples were then
centered across a 1-cm span and supported on either side by a 1-cm-wide block.
A load was applied to the center of the tissue. The force required to deform
the tissue over a vertical travel of 8 mm was recorded by means of a 50-N
load cell. Rate of travel of the load cell arm was 12.7 mm/min. Thickness
for the samples was determined by means of a vernier micrometer, as described
above.
For analysis, the load vs extension curve was plotted, and a third-degree
best-fit trend curve was applied. The maximum deformation load applied was
graphically determined from the trend line. Three-point bend values were computed
as follows: (3.0 x maximum load x span)/(2 x width x
thickness2).
RESULTS
MICROSCOPY
All specimens demonstrated architecture with varying degrees of similarity
to that of the source tissue. No viable cells were noted in any specimen.
The AlloDerm specimen (Figure 1)
showed intact, normally oriented collagen bundles with interspaced discrete
elastin fibers. The epidermis was absent, but the rete pegs, upper dermal
border, and basement membrane appeared intact. Collagen fibers appeared grossly
normal, measuring 10 to 25 µm in width, with spacing and configuration
similar to those of normal human dermis. "Congealed" cell cytoplasmic remnants,
conforming to anatomic structures of pilosebaceous units and sweat glands,
were scattered throughout the specimen, but internal cellular structures including
nuclei were not observed. These remnants of dermal structures, as well as
the pattern and distribution of collagen and elastin fibers, mirrored untreated
dermis and allowed identification of the papillary and reticular dermis. AlloDerm
measured approximately 2500 µm in thickness.
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Figure 1. A, Surface of AlloDerm dermal
graft, showing abundant collagen bundles with normal spacing and configuration,
along with nuclear debris of pilosebaceous units (hematoxylin-eosin, original
magnification x10). B, Full-thickness view of AlloDerm with intact upper
dermal border, normal-appearing collagen, and elastin fibers (Movat stain,
original magnification x25).
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DuraDerm (Figure 2) appeared
to lose some definition of architecture. The epidermis was absent and the
upper dermis was compressed, forming an acellular band at the surface. Rete
peg structures were not discerned. The dermal collagen fibers were contracted,
compared with normal untreated dermis, and measured 4 to 10 µm in width.
Collagen fibers were also widely spaced, separated by a very watery mucopolysaccharide
remnant of intercellular ground substance, as noted on Movat staining. No
distinction between papillary and reticular dermis could be made. Less cellular
debris was seen than in AlloDerm; however, nearly intact casts of dermal structures
such as capillaries and sebaceous glands were occasionally seen. The specimen
of DuraDerm examined uniformly measured 1500 µm thick.
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Figure 2. A, Surface of DuraDerm dermal
graft with compressed collagen bundles and nearly intact capillaries (hematoxylin-eosin,
original magnification x10). B, Full-thickness cut of DuraDerm also
showing a preserved upper dermal border (Movat stain, original magnification
x25).
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The collagen fibers in Tutoplast fascia lata (Figure 3) closely approximated the appearance of unprocessed fascia
lata, with intact collagen fibers 10 to 25 µm in thickness with normal
orientation. No elastic fibers were seen. Scattered accumulations of nuclear
remnants were seen throughout the specimen. The Tutoplast fascia lata specimen
varied in thickness from 800 to 1000 µm.
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Figure 3. A, Surface of Tutoplast fascia
lata, closely resembling unprocessed fascia (hematoxylin-eosin, original magnification
x10). B, Full-thickness view of Tutoplast fascia lata showing a relatively
uniform distribution of collagen fibers (Movat stain, original magnification
x25).
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The appearance of cadaveric fascia lata (Figure 4) differed little from that of Tutoplast fascia lata. Again,
regularly oriented collagen fibers 10 to 25 µm in thickness were seen.
Significantly more deposits of nuclear debris were seen in the cadaveric specimen
than in the Tutoplast-processed fascia. The cadaveric fascia lata examined
uniformly measured 500 µm in thickness.
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Figure 4. A, Surface of irradiated cadaveric
fascia lata, with more nuclear remnants than in the Tutoplast-processed specimen
(hematoxylin-eosin, original magnification x10). B, Full-thickness view
of cadaveric fascia lata shows dense collagen fibers with interspaced clefts
and nuclear debris (Movat stain, original magnification x25).
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SCANNING ELECTRON MICROSCOPY
Scanning electron microscopy (Figure
5) demonstrated a dense arrangement of collagen fibers interspersed
with small clefts in AlloDerm. By contrast, DuraDerm had a similar arrangement
of collagen fibers; however, there was a substantially greater degree of clefting
and a number of "pores."
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Figure 5. Scanning electron micrographs
of AlloDerm (A), DuraDerm (B), Tutoplast fascia lata (C), and irradiated cadaveric
fascia lata (D) (original magnification x15).
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Tutoplast fascia lata demonstrated uniform, discrete, and parallel collagen
bundles on scanning electron microscopy, in contrast to cadaveric fascia lata,
which appeared to be a more uniform surface without distinct collagen fibers.
BIOPHYSICAL TESTING
Sample thickness as measured by physical micrometry correlated well
with measurements by microscopy. AlloDerm was significantly thicker than DuraDerm,
and both of these were thicker than either cadaveric or Tutoplast fascia lata
(1.89 vs 1.33 vs 0.77 vs 0.77 mm; both comparisons P
= .03) (Figure 6). Maximum load
to breaking was significantly lower in DuraDerm than in either Tutoplast fascia
lata or Alloderm; similar findings were noted with cadaveric fascia lata (Figure 7). Maximum stress and modulus of
elasticity were significantly higher in cadaveric and Tutoplast fascia lata
than in either DuraDerm or AlloDerm; these were also higher in DuraDerm than
in AlloDerm (Figure 8 and Figure 9). Three-point bend testing showed
that conformability was greatest in AlloDerm and least in cadaveric fascia
lata (Figure 10).
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Figure 6. Thicknesses of Tutoplast fascia
lata, cadaveric fascia lata, DuraDerm, and AlloDerm, as measured by calipers
(AlloDerm vs DuraDerm, P = .03; both vs cadaveric
fascia lata and Tutoplast fascia lata, P = .03; error
bars represent 1 SD from the mean).
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Figure 7. Maximum load sustained (AlloDerm
vs cadaveric fascia lata, P = .01; AlloDerm vs DuraDerm, P = .02; Tutoplast vs DuraDerm, P
= .02; error bars represent 1 SD from the mean).
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Figure 8. Maximum stress tolerated before
breaking (Tutoplast fascia lata vs cadaveric fascia lata, AlloDerm, and DuraDerm, P = .03, .01, and .004, respectively; cadaveric fascia
lata vs DuraDerm, P = .002; AlloDerm vs DuraDerm, P = .01; error bars represent 1 SD from the mean).
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Figure 9. Modulus of elasticity (cadaveric
fascia lata > Tutoplast fascia lata > DuraDerm > AlloDerm, P = .048, .002, .01; error bars represent 1 SD from the mean).
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Figure 10. Results of 3-point bend testing;
lower values indicate greater material conformability (cadaveric fascia lata
> Tutoplast fascia lata > DuraDerm > AlloDerm, P<.001, P = .048, .02; error bars represent 1 SD from the mean).
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COMMENT
Homologous soft tissue grafts are useful for a variety of cosmetic and
reconstructive applications in the face, head, and neck. They have been used
for repair of congenital ptosis; in static sling procedures for facial paralysis;
as scaffolding in the repair of nasal septal perforations; for obliteration
of soft tissue defects such as depressed scars; and for augmentation of facial
areas such as the nasal dorsum, nasolabial folds, and lips. These proteinaceous
materials of human origin are all resorbed to some degree after implantation,
but some fibrous invasion does occur. The ultimate success of procedures that
use these materials is affected by their initial bulk and structural integrity,
as well as the biological processes that affect them after implantation.
The materials examined in this study are derived from either dermis
or fascia. AlloDerm and DuraDerm are both derived from dermis and are subsequently
decellularized and freeze-dried by patented processes. Tutoplast fascia lata
and cadaveric fascia lata are also processed and treated to remove donor cells
and major histocompatibility antigens. The processing that homologous tissues
require to eliminate antigenicity may lead to structural degradation of the
protein network. Damage to these (predominantly) collagen fibers, as well
as incomplete removal of degradation products, may compromise the integrity
of these materials, as well as promote a graft-vs-host reaction by exposing
new collagen epitopes to host inflammatory cells.
In this study, we have examined the gross, microscopic, and ultrascopic
morphologic characteristics of 4 readily available homologous soft tissue
materials. Dermis-based materials like AlloDerm and DuraDerm show collagen
(and elastin) fiber networks in a heterogeneous pattern. These acellular proteinaceous
materials differ, however, in more subtle ways. AlloDerm appeared to be more
organized than DuraDerm, with a more consistent surface texture as seen on
scanning electron microscopy. AlloDerm appeared much more compact and coherent
than did DuraDerm; the interstices between collagen bundles were markedly
larger in DuraDerm and appeared to be expanded by a dilute mucopolysaccharide.
When used for soft tissue augmentation or replacement, fluid flux across a
DuraDerm implant may lead to a situation in which accurate assessment of the
required material is difficult, as the apparent volume of the ex vivo implant
may be significantly different from its true volume once it is implanted and
the mucopolysaccharide is resorbed.
Both fascia lata–based materials demonstrated bland, uniform acellular
bands of collagen bundles. However, cadaveric fascia lata showed fine separations
between collagen fibers and large gaps between collagen bundles; collagen
fibers in Tutoplast fascia lata were much more tightly compacted. Interestingly,
significant amounts of presumed nuclear remnants were present in both specimen,
more so in the cadaveric fascia lata than in the Tutoplast fascia lata. This
material potentially could elicit an inflammatory response, leading to enhanced
graft resorption.
The ex vivo features of homologous soft tissue materials will have a
direct impact on their utility and long-term success, which will also be affected
by host factors. Boyce et al1 and Muldashev
et al2 believed that replacement tissues fare
better when they more closely resemble the tissues of the host bed. The absence
of a healthy vascular bed will ultimately lead to severe degeneration and
resorption of the allograft. Das et al,3 working
with autologous fascia, concluded that the success of a fascial graft was
determined by the thickness of the graft and the vascular quality of the recipient
bed. A vascular bed provides a reserve of inflammatory tissue that can invade,
repopulate, replace, or resorb an allograft, and any compromise of the host
tissue bed may delay the incorporation of the graft. Ibrahim et al4 noted complete, albeit delayed, fibroblast repopulation
and neovascularization of AlloDerm grafts in the setting of early postoperative
radiation therapy.
Testing of the fascial and dermal materials showed differences in biophysical
properties. As expected, dermal materials were notably thicker than the fascia
lata. Fascial materials were stiffer and less elastic, in general, than dermal
derivatives. AlloDerm, however, was slightly more elastic than DuraDerm, and
the maximum load to breaking was twice as great in AlloDerm than in DuraDerm.
Our results correlate well with the data presented by Lemer et al5 (differences in absolute values between these 2 studies
are related to differences in technique). Changes to the protein matrix during
the processing of DuraDerm may adversely affect the elasticity and strength
of the material. Tutoplast fascia lata and AlloDerm sustained greater loads
before breaking than did either cadaveric fascia lata or DuraDerm. These data
suggest that variations in processing, despite similar source tissues, can
have significant effects on the physical characteristics of these tissues.
This finding would suggest, for example, that DuraDerm is, to some degree,
degraded more from natural dermis than is AlloDerm, as AlloDerm is able to
tolerate a greater load but retains greater elasticity than DuraDerm.
A number of investigators have confirmed a dynamic inflammatory response
to allograft implantation, which appears to correlate with clinical observations.
Muldashev et al2 observed that, after placement
of dermis, fascia, or tendon allografts, a severe lymphocytic and neutrophilic
reaction was seen around the allograft 20 days after graft placement, with
subsequent decline in severity; these workers found that the postimplantation
inflammatory reaction could be reduced if the glucosaminoglycans were extracted
from the collagen fibers before implantation. Merritt et al6
documented an increase in local collagen production after transplantation
of fascia lata autografts and allografts, and initially postulated that the
clinically observed decrease in fascial strength was related to a synchronous
enhancement of collagen degradation. In a subsequent article, however, Merritt
et al7 found that the transplanted fascia was
not the mediator of the increased collagen production, which was viewed as
part of the recipient wounding response. FitzGerald et al8
noted repopulation of freeze-dried fascia lata by host fibroblasts, with varying
degrees of cellularity and organization and inflammatory cells in a specimen
removed 7 months after insertion. These authors postulated a process of initial
degeneration of the collagen fibers, followed by repopulation by host blood
vessels and fibroblasts. This repopulation is believed to stabilize the biomechanical
qualities of the graft, after an early period of decreasing strength. Broughton
et al9 noted a 20% early (first 3 months postoperatively)
failure rate. Curtis et al10 found a period
of weakness between 6 and 12 weeks that later stabilized in dogs undergoing
anterior cruciate ligament reconstruction with freeze-dried fascia lata. Graft
integrity appears to stabilize by 3 to 6 months after implantation. Aebi et
al11 described transplanted autogenous fascia
lata in monkeys and found degeneration of collagen fibers at 3 months, with
subsequent fibrosis by 6 months. Orlando et al12
harvested fascia lata 42 years after transplantation and noted indistinct
margins, with incorporation of adjacent fat muscle and nerve into the fascia.
Factors acting on the graft will also affect long-term survival and
performance. Evaluating irradiated fascia, Cutz et al13
noted a decrease in tensile strength in tissue irradiated with 4.0 Mrad compared
with 2.7 Mrad. Thomas et al14 found that fascial
stiffness could be enhanced and strain reduced when the material was tubulized.
However, rolling or stacking fascia creates an internal volume of graft that
is not in direct contact with the host vascular bed. This area of relatively
starved tissue will show a decrease in viable fibroblasts, even while gross
volume may remain unchanged.1 Burres15 advocated the use of diced, freeze-dried fascia lata
for lip augmentation, claiming 6 to 12 months of persistence. By implanting
small pieces of material, host incorporation of the material presumably may
be enhanced; however, this process may also subject the material to greater
resorptive forces.
The lower elasticity of fascia compared with dermis-derived grafts is
expected and can be related to the microscopic findings. The tighter parallel
organization of collagen fibers together with the absence of elastin fibers
in fascia are similar to in vivo fascia. The elasticity of the dermal materials
examined is similar, but AlloDerm had a significantly greater loading strength
than did DuraDerm and was equivalent to that of Tutoplast fascia lata. Clearly,
these features should be taken into consideration when different applications
for these materials are considered. Different materials may be of varying
utility in procedures where the grafts will be placed under considerable tension
and are used for structural support. For example, Tutoplast fascia lata or
AlloDerm may be a better choice for static sling procedures for facial paralysis
than DuraDerm, given the latter's lower breaking strength. AlloDerm may need
to be prestretched before placement, given its greater elasticity than fascia
lata, to avoid early "stretch-back" and loss of support. The higher elasticity
in AlloDerm compared with fascial lata and DuraDerm may explain the suboptimal
results found in the first 2 cases reported by Fisher and Frodel.16 If these materials are to be used purely for soft
tissue replacement or augmentation, a more important feature may be the relative
"purity" of the material from remnant cellular debris, such as nucleic acid
breakdown products, which may act as antigenic stimuli. Also, dermal materials
are considerably thicker than fascia-derived grafts and are better for adding
bulk to soft tissues. The significantly greater protein density of AlloDerm
compared with DuraDerm may also affect the final degree of augmentation produced
with these 2 materials. Histologic and persistence studies of DuraDerm have
not yet been published; unless significant host ingrowth and augmentation
of the DuraDerm occur, this material may not yield adequate long-term results.
The most obvious concern about allograft materials is their safety.
The potential for disease transmission exists when tissue is transplanted
from one organism to another. Clarke17 described
a case of human immunodeficiency virus (HIV) transmission after allograft
skin was used for temporary wound coverage. Between 1985 and 1994, only 2
cases of HIV transmission from donor to recipient were documented, from more
than 1 million tissue transplant operations.18
Simonds et al19 described transmission of HIV
to 7 of 41 tested recipients of tissue from a donor who was subsequently found
to be HIV positive. All of those who seroconverted received implants of either
whole organs or unprocessed fresh-frozen bone. No patients receiving lyophilized,
ethanol-treated, or gamma-irradiated tissues or marrow-evacuated fresh-frozen
bone became HIV positive.
All of the materials examined in this study are processed in ways that
reduce the potential for disease transmission. The fascia lata materials were
terminally gamma-irradiated, while the dermal materials were chemically decellularized.
In addition, one proprietary step in the processing of skin into AlloDerm
has been shown to inactivate HIV in vitro. In light of this, acellular tissue
grafts, with subsequent chemical or radiation treatment, are preferable to
whole organ or cellular transplants in reducing the potential for HIV transmission.
CONCLUSIONS
The processing of homologous tissue is designed to remove immunogenic
structures, but should allow the tissue remaining to maintain its normal structure.
Radiation and lyophilization are known to degrade tissue to varying degrees,
and the surgeon, when choosing an allograft, should consider how different
homologous tissue are processed and how degraded they become. Of the fascial
materials, Tutoplast fascia lata retains a greater degree of the microscopic
structure of untreated fascia than does cadaveric fascia lata. In addition,
its biophysical qualities are closer to native fascia than those of cadaveric
fascia lata.
AlloDerm and DuraDerm are both derived from human skin, but the different
manufacturing processes involved alter these tissues in different ways. On
the basis of both the microscopic appearance and the biophysical qualities
of these materials, AlloDerm appears to retain more dermal features and qualities
than does DuraDerm. AlloDerm is stronger and more elastic and appears very
similar to normal dermis microscopically. Theoretically, this should be associated
with a higher persistence rate in vivo and more useful and predictable success
in facial plastic and reconstructive surgery. Clinical trials are currently
under way to test this hypothesis.
AUTHOR INFORMATION
Accepted for publication January 11, 2001.
The costs of this study were underwritten by LifeCell Corp, Branchburg,
NJ.
Biophysical testing was performed by Sy Griffey, PhD, of LifeCell Corp.
Corresponding author and reprints: Anthony P. Sclafani, MD, Division
of Facial Plastic and Reconstructive Surgery, The New York Eye & Ear Infirmary,
310 E 14th St, Sixth Floor, New York, NY 10003 (e-mail: drsclafani{at}nyfacialsurgery.com).
From the Division of Facial Plastic and Reconstructive Surgery (Drs
Sclafani and McCormick) and the Department of Pathology (Drs McCormick and
Cocker), The New York Eye & Ear Infirmary, New York. No author holds any
financial interests in any of the manufacturers of the tested materials.
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