A, Graph of the mean percentage
volume persistence of acellular dermal graft (AlloDerm) vs type I bovine collagen
cross-linked with glutaraldehyde (Zyplast) over a 12-month period. B, Graph
of AlloDerm and Zyplast mean percentage volume persistence for each patient
over a 12-month period.
Acellular dermal graft (AlloDerm)
implant explanted at 12 months. Vibrant ingrowth of the implant by fibroblasts
and blood vessels (hematoxylin-eosin, original magnification ×10).
Sclafani AP, Romo T, Jacono AA, McCormick SA, Cocker R, Parker A. Evaluation of Acellular Dermal Graft (AlloDerm) Sheet for Soft Tissue AugmentationA 1-Year Follow-up of Clinical Observations and Histological Findings. Arch Facial Plast Surg. 2001;3(2):101-103. doi:
From the Division of Facial Plastic Surgery (Drs Sclafani and Romo),
and the Departments of Otolaryngology–Head and Neck Surgery (Drs Sclafani,
Romo, Jacono, and Parker) and Pathology (Drs McCormick and Cocker), The New
York Eye and Ear Infirmary, New York; and the Department of Otolaryngology–Head
and Neck Surgery, New York Medical College, Valhalla (Drs Sclafani and Romo).
Objectives To evaluate and compare the long-term clinical persistence and histological
appearance of subdermally implanted acellular dermal graft (AlloDerm) sheets
and intradermal type I bovine collagen cross-linked with glutaraldehyde (Zyplast).
Patients Ten adult patients (5 men and 5 women; average age, 46 years; age range,
37-59 years) not allergic to bovine collagen.
Methods AlloDerm sheets were implanted surgically in a subdermal plane in one
postauricular crease, and Zyplast was injected intradermally on the opposite
side. AlloDerm and Zyplast implants were digitally photographed and their
apparent volumes calculated at 1, 3, 6, 9, and 12 months after implantation.
A specimen was removed at 3 and 12 months and examined histologically for
collagen persistence, host tissue invasion, and inflammatory reaction.
Results The apparent implant volume of the AlloDerm sheets decreased during
the first 6 months and then stabilized over the next 6 months. By contrast,
Zyplast was progressively absorbed, with complete loss of clinical effect
by 6 months. Histological analysis of implanted AlloDerm sheets demonstrated
progressive repopulation of the graft with minimal inflammation.
Conclusions AlloDerm sheets seem to provide stable soft tissue augmentation after
an early period of resorption and are clearly superior to Zyplast injections
for long-term, large-volume, soft tissue correction. Recommendations for clinical
use include routine overcorrection, with subsequent augmentation delayed by
at least 6 months.
WE PREVIOUSLY reported a comparative study of the macroscopic and microscopic
changes of subdermally implanted acellular dermal graft (AlloDerm; LifeCell
Corp, Branchburg, NJ) sheets and intradermally injected type I bovine collagen
cross-linked with glutaraldehyde (Zyplast; Collagen Corp, Palo Alto, Calif).1 In this article we provide 1-year follow-up data on
Adult patients seen at The New York Eye and Ear Infirmary, New York,
between November 1, 1997, and February 28, 1998, were given the opportunity
to participate in this study. Interested patients were asked to sign a consent
Patients were tested for allergic reaction to bovine collagen in the
standard fashion and observed for any adverse reaction for at least 30 days.
Only patients who had previously been treated with bovine collagen without
reaction or those who had negative Zyderm skin test results were allowed to
participate in this study.
Participating patients were anesthetized with a topical anesthetic agent
(a combination of lidocaine and prilocaine hydrochloride in an emulsion base;
Astra USA, Marlborough, Mass) over both postauricular areas for a minimum
of 20 minutes. Patients were then injected intradermally in 2 sites (0.50
mL of Zyplast each) in the skin overlying one mastoid (just posterior to the
postauricular crease), separated by at least 2 cm, using a template referenced
to the Frankfort horizontal line. The material was injected in small volumes
serially and occupied no larger than a 10-mm-diameter circle; care was taken
to avoid migration of the injectant into the skin directly in the postauricular
crease. AlloDerm was placed behind the opposite ear. After infiltration with
1% lidocaine, a 1.5-cm horizontal incision was made and subcutaneous pockets
were developed superiorly and inferiorly, again using the standard template.
AlloDerm sheets (approximately 1 mm thick) were sterilely cut into circular
pieces with an 8-mm-diameter dermal punch. After rehydration in 2 separate
baths of sterile isotonic sodium chloride solution for 5 minutes each, a stack
of five 8-mm AlloDerm disks was placed into each pocket, separated by at least
2 cm. The wound was closed with 5-0 nylon sutures, which were removed on postoperative
The patients returned for follow-up visits at 1 week and 1, 3, 6, 9,
and 12 months after the initial injection. At each visit, the implant sites
were inspected and the patients were questioned regarding pain, fever, swelling,
redness, and any other local or systemic sign or symptom that had developed
since the injections. Standardized lateral and posterior digital photographs
were taken at 1, 3, 6, 9, and 12 months after implantation with a digital
imaging system (Mirror 2000; Virtual Eyes, Kirkland, Wash). This system allowed
for measurement of the surface area and lateral projection of the implant.
These 2 data points were used to calculate the volume of the implant by assuming
a cylindrical form of the implant and multiplying the surface area by the
lateral projection. The percentage of implant persistence at 1, 3, 6, 9, and
12 months was obtained by dividing the calculated volume of the implant by
the originally implanted volume. AlloDerm volume at implantation was calculated
by multiplying the surface area of an 8-mm-diameter disk by the predehydration
thickness of the AlloDerm sheet, as measured by the manufacturer with a 3-dimensional
One implant of each type was localized (using the reference template)
and removed at the 3- and 12-month visits under local anesthesia, and the
wound was closed with interrupted 4-0 chromic sutures. Pathologic specimens
were sectioned and stained with hematoxylin-eosin and with Movat pentachrome.
The sections were examined by light microscopy under low and high power and
inspected for implant location and persistence, fibroblast infiltration of
the implant, and short- or long-term inflammatory response. Fibroblastic activity
was described as either none, or intraimplant, based on the presence and location
of the fibroblasts. Inflammatory activity was described as none, peri-implant,
or intraimplant, based on the presence and location of the inflammatory cells;
the presence of giant cells was also noted. This study was approved by the
New York Eye and Ear Infirmary Institutional Review Board for the Protection
of Human Subjects.
Ten patients were enrolled (5 men and 5 women; average age, 46 years;
age range, 37-59 years). Owing to variations in the thickness of AlloDerm
sheets, the volume of implanted AlloDerm varied between 0.22 and 0.29 mL.
No patients experienced any signs or symptoms of implant infection, rejection,
allergic reaction, or extrusion.
AlloDerm persistence at all points was statistically greater than that
for Zyplast. The mean percentage volume persistence of AlloDerm at 1, 3, 6,
and 12 months was 82.8%, 48.3%, 21.9%, and 20.2%, respectively, while the
mean percentage volume persistence of Zyplast at 1, 3, 6, and 12 months was
26.6%, 8.0%, 1.1%, and 0.9%, respectively (P<.001
at all times, unpaired t test) (Figure 1). Owing to equipment malfunction, most patients did not
have photographs taken at the 9-month visit.
Implant material was noted in all of the AlloDerm and Zyplast 3-month
biopsy specimens. Intraimplant fibroblast activity was noted in all of the
AlloDerm specimens but not in any of the specimens with Zyplast. Minimal peri-implant
inflammation was observed around all specimens in both the AlloDerm-treated
and Zyplast-treated groups. No giant cell reaction was noted in either treatment
Twelve-month biopsy specimens of the AlloDerm implants showed extensive
host ingrowth with mature blood vessels and fibroblasts (Figure 2). No islands of Zyplast were identified in any specimen.
Our investigation has demonstrated the clinical superiority of AlloDerm
over Zyplast for soft tissue volume augmentation. The clinical effect of AlloDerm
is evident for at least 6 to 12 months after implantation. While in our model
only approximately 20% of the implanted volume was evident at 6 months, further
loss of volume did not seem to occur. This may be somewhat related to the
stacking of AlloDerm done in our model, as the central pieces of AlloDerm
must rely on vascular ingrowth from the disk periphery or through the overlying
or underlying pieces of AlloDerm, rather than by direct apposition of their
broader surface direct against the recipient soft tissue bed. This may predispose
toward enhanced early resorption. This stacking of subdermal AlloDerm (volumetrically
less than the amount of Zyplast injected) was necessary to produce a measurable
degree of externally evident skin displacement. However, AlloDerm is often
rolled or folded on itself in clinical scenarios such as correction of deep
nasolabial folds or the atrophic lip, thus producing a "hidden" portion of
Clearly, a certain degree of overcorrection is necessary with AlloDerm,
given the clinical loss of volume. The degree of overcorrection most likely
varies based on local factors, such as the amount and location of AlloDerm
placement, local tissue environment (irradiated tissues, placement over bone
or in scar tissue, and others), and rheologic properties of surrounding tissue
and skin. Additionally, secondary "touch-up" procedures should be delayed
at least 6 months after implantation to allow for stabilization and equilibration
of the original implant. In this study, both materials were used to augment
tissue volume, not to replace it. The rate of implant resorption may differ
in the setting of volume replacement as different remodeling forces may be
Histologically, at 3 months, there was a significant difference in the
degree of intraimplant fibroblasts, with all AlloDerm implants showing intraimplant
proliferation of fibroblasts, and Zyplast revealing none. There was no significant
difference in the mild degree of peri-implant inflammation noted in both groups.
Biopsy specimens at 12 months confirm the invasion of AlloDerm by host fibroblasts,
as well as revascularization. Zyplast does not persist at 12 months and is
mostly resorbed by 3 months. The peri-implant inflammatory cells and possibly
the intraimplant fibroblasts most likely mediate this resorption, in distinction
to the collagen homeostasis mediated by the fibroblasts populating the AlloDerm
Accepted for publication September 6, 2000.
Corresponding author: Anthony P. Sclafani, MD, Division of Facial
Plastic Surgery, The New York Eye and Ear Infirmary, 310 E 14th St, North
Bldg, Sixth Floor, New York, NY 10003 (e-mail: firstname.lastname@example.org).