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21 Advancements inDermal Substitutes forHead andNeck Reconstruction
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Fig. 21.1 Integra Wound
Matrix System used to treat a
scalp wound due to dog bite
in a 59-year- old female. (a, c)
Negative pressure wound
therapy of scalp defects. (b,
d) Scalp wounds following
negative pressure therapy.
Scalp wounds (e) pre- and (f)
post-local advancement ap
surgery. (g–h) Application of
Integra Wound Matrix
System in residual defect.
Note the outer black threads
that identify the silicone layer
of the matrix. (i, j) Two
weeks post-surgery (Images
courtesy of Dr.
Jonathon Jundt)
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c d
ef
gh
ij
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S. A. Wong et al.
Integra Postoperative Management
1. Change the secondary dressings as needed. The frequency at which secondary
dressing are changed will depend upon the volume of exudate produced, the type
of dressing used, and the clinician’s need to inspect the wound for signs of infection or healing.
2. Removing the Integra silicone layer:
(a) If the edges of the matrix are loose before full healing has occurred, care-
fully trim away the loose silicone leaving the attached silicone in place.
Repeat until the entire wound has healed.
(b) Remove the silicone layer once the underlying tissue has healed, typically
14–28days. Note: It is normal for the matrix to be loose in some spots.
(c) When removing the silicone layer, start at one corner and pull gently. Note:
Healed tissue can easily peel away along with the silicone layer.
(d) Stop and wait 1–2 additional days if bleeding occurs or patient reports
excessive pain. Forced removal of the silicone layer may result in reinjury.
3. If using negative pressure wound therapy:
(a) The device will need to be removed during dressing changes. Take care not
to disrupt the Integra matrix during this process.
(b) Discontinue use of negative pressure wound therapy when the Integra col-
lagen matrix has integrated with surrounding tissues and the silicone layer
has separated. Using negative pressure therapy will likely reduce the time
required for wound healing. Healing without negative pressure therapy typically occurs in 14–28days.
AlloDerm
Introduced in 1994 as a treatment for full-thickness burns, AlloDerm was one of the
rst dermal matrix products reported in the literature [26]. It currently has a wide
variety of applications including rhinoplasty, facial soft-tissue defect augmentation,
abdominal wall reconstruction, alloplastic breast reconstruction, radial forearm
free-ap donor site coverage, and vaginal repair [27]. In the eld of maxillofacial
surgery, AlloDerm is primarily used as a wound bed graft or as an implant to repair
and replace damaged or inadequate integumental tissue [9].
AlloDerm is a human acellular dermal graft that is biochemically intact [27]. The
use of this device often requires the application of an overlying skin graft. The
device has two distinct surfaces, a “dermal” side and a “basement membrane” side.
The dermal side exhibits greater plasma imbibition and is placed in contact with the
most vascularized surface. The basement membrane surface serves as an attachment
site for migrating stem cells from the overlying skin autograft.
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AlloDerm Recommended Protocol
1. Open the outer foil bag, and remove the inner Tyvek pouch. Both the foil bag and
Tyvek pouch should be kept out of the sterile eld. Using sterile technique, open
the inner Tyvek pouch and remove the enclosed matrix. Do not remove the paper
backing at this time.
2. Completely immerse the matrix in sterile saline for at least 5 min or until the
backing separates from the AlloDerm matrix.
(a) Warming the saline solution as high as 37°C and gently rocking the rehy-
dration bath to provide slight mechanical motion will speed the rehydration
process. It is important NOT to heat the saline solution above 37°C.
(b) If simultaneously rehydrating multiple matrix pieces, ensure that the pieces
do not overlap or stick together as this may slow the rehydration process.
Instead, rehydrate matrices in separate containers.
(c) Ensure that the AlloDerm matrix remains fully submerged by weighing it
down with a sterile object, such as sterile forceps.
(d) If the AlloDerm matrix does not achieve complete rehydration, gently wipe/
rub both sides of the matrix with a sterile gloved hand to remove excess
cryoprotectant material that may be preventing the rehydration uid from
contacting the AlloDerm matrix.
3. Aseptically remove and discard the paper backing once it separates from
the matrix.
4. Transfer the matrix to a second bath sufciently lled with rehydration uid. As
before, ensure that the matrix is completely submerged, and soak the matrix until
it is fully rehydrated (this may take up to 40min for thicker grafts).
(a) The graft should be soft and pliable throughout once it is fully rehydrated.
Once this has been achieved, the graft is ready for implantation and should
be inserted within 4h of rehydration.
5. Trim AlloDerm matrix to required dimensions prior to insertion.
6. Determine the proper orientation of the AlloDerm matrix, and insert as
appropriate.
(a) Identify the distinct surfaces of the AlloDerm matrix once it has been rehy-
drated by adding a drop of blood to both sides and rinsing with rehydration
solution. The dermal side will appear bloody, whereas the basement membrane side will appear pink. When applying AlloDerm to a wound bed during grafting procedures, the dermal side should be placed in direct contact
with the wound bed, and the basement membrane side should face in the
opposite direction, toward the surface of the wound. When AlloDerm is used
as an implant, the dermal side of the matrix should be placed against the
most vascularized tissue.
7. Following AlloDerm insertion, place an overlying skin autograft, and secure
using preferred techniques.
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8. Place an inner dressing of petrolatum-impregnated gauze to reduce moisture
loss, and secure using appropriate outer secondary dressings. A damp saline
layer may also be applied to increase moisture retention at the wound site.
S. A. Wong et al.
AlloDerm Postoperative Management
1. During the rst few postoperative days, the outer dressing layers may require
frequent changing in order to prevent accumulation of uid and bacteria. It is
critical that the AlloDerm matrix and overlying autograft remain undisturbed in
order to achieve sufcient revascularization and re-epithelization. To prevent
reinjury, do not disturb the inner dressing of petrolatum-impregnated gauze for
at least 7days, after which use extreme care when removing the inner dressing.
Prior to removing the inner dressing, generously apply petrolatum-based ointment to prevent adherence and to reduce stress applied to the grafted areas.
Soaking the wound area with saline may also be effective when removing the
dressing.
2. Around day 7 post-surgery, it is normal for the AlloDerm graft to appear white/
yellow in some areas. It is also common for the skin autograft to appear whiter
than the surrounding epidermis and to only weakly adhere at this time.
3. Continue to redress the surgical site with antibiotic-impregnated ne mesh gauze
or other nonadherent dressings until the graft has fully re-vascularized and reepithelized. A damp saline layer is no longer necessary at this time.
4. If all or part of the autograft is removed with the dressing, this does not always
require regrafting. If sufcient epidermal cells have migrated from the autograft
to the basement membrane, regrafting will not be needed.
5. If using a meshed graft, epithelial cell growth under the thin dermal layer of the
autograft may cause it to detach. Regrafting may not be needed if sufcient epidermal cells have seeded the surface of the AlloDerm matrix to provide sufcient wound coverage prior to autograft detachment. The surface of the AlloDerm
matrix should be carefully examined to determine if regrafting is required.
6. Protective dressings may be eliminated as the cornied layer of the newly formed
skin is established (10–14days). At this point, bathing with mild soaps and limited activity may commence.
ACell (Cytal, Gentrix, MicroMatrix)
ACell is derived from porcine urinary bladder mucosa (UBM). It is the only commercially available form of UBM and consists of two layers, a lamina propria that
promotes cellular inltration and neovascularization and a basement membrane
layer that supports cell proliferation and neodermis formation. ACell comes in
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several formulations, including sheet (Cytal, Gentrix) and particulate forms
(MicroMatrix).
ACell’s sheet formulations come in 3-, 6- (Cytal® Surgical Sheets), and 8-layered
varieties (Gentrix® Surgical Thick Sheets). These formulations take longer to
degrade than the MicroMatrix powder and provide a sustained response that lasts
over the course of 1 week or longer, depending on the degree to which the device is
packed into the wound. The suture-holding capacity of ACell’s sheet formulations
make them useful in securing the skin margins of an open wound, reducing skin
closure tension, and retaining other ACell formulations placed deeper in the wound.
ACell’s MicroMatrix is created by grinding Cytal Surgical Sheets into powder.
Due to its small particle size, this formulation has a rapid breakdown, resulting in a
faster and more robust healing response. MicroMatrix can be applied directly as a
powder or mixed with saline to create a thick injectable slurry. MicroMatrix has
been useful in treating chronic wounds where stimulation of a robust healing
response is needed as well as wounds in patients who are poor surgical candidates [3].
Some wounds, such as those of the scalp and forehead, heal slower and often
require several applications of ACell devices in order to achieve complete closure or
to reach sufcient healing to permit skin grafting. Treatment with MicroMatrix can
be applied serially with alternate day treatments or with single placement of a large
volume. It has been noted that applying larger amounts of ACell as well as simultaneous placement of multiple formulations of the device at the time of initial wound
bed preparation leads to better outcomes with fewer revision surgeries and improved
patient comfort [3].
In addition to the above, ACell devices have numerous clinical indications
including partial and full-thickness wounds, a variety of ulcers (pressure, venous,
diabetic, chronic vascular), surgical wounds (donor sites/grafts, post-Mohs surgery,
post-laser surgery, wound dehiscence), traumatic wounds (abrasions, lacerations,
second-degree burns, skin tears), tunneled and undermined wounds, and noninfected draining wounds [9].
Unlike most dermal substitutes, ACell has demonstrated clinical success when
treating wounds challenged with bacterial infection [28]. Studies have shown that
treatment with UBM promotes an anti-inammatory (M2) macrophage phenotype,
reducing the ratio of pro-inammatory (M1) to anti-inammatory (M2) macrophages [29]. This is signicant since M1 macrophages are associated with scar formation, whereas M2 macrophages have been associated with tissue remodeling and
improved wound repair [29]. Clinically, it has been noted that patients treated with
ACell experience decreased swelling, scarring, and pain both at early and late stages
of healing [3]. Furthermore, while treatment with ACell does not restore skin
appendages, wounds healed using this device are amenable to hair follicle grafting
procedures [3].
Below is our recommended ACell protocol along with clinical examples of using
this dermal substitute to treat radial forearm (Figs.21.2 and 21.3) and bula ap
donor sites (Fig.21.4).
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S. A. Wong et al.
a
b
c
Fig. 21.2 ACell used to treat a radial forearm ap donor site. (a) Radial forearm ap harvested
from donor site. (b) Flap donor site after placement of ACell Cytal Wound Matrix. (c) Complete
neo-epithelization 3months post-surgery (Images courtesy of Dr. James Melville)
abcd
Fig. 21.3 ACell used to treat a radial forearm ap donor site. (a) Placement of Cytal Wound
Matrix dermal substitute. Progression of wound healing at (b) 2weeks and (c) 3months following
application of dermal substitute. (d) Complete neo-epithelization achieved 4months post-surgery
(Images courtesy of Dr. James Melville)
a
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381
b
d
c
e
Fig. 21.4 ACell used to treat a nonhealing bula ap donor site in a 70-year-old male with past
medical history of hypertension, congested heart failure (ejection fraction (EF) 31.55%), and myocardial infarction (MI). Patient was diagnosed with stage IV oral squamous cell carcinoma of the
right mandibular gingiva (T4aN3bM0). (a) Intraoral clinical picture showing 4.5× 6cm erosive
ulcer in the right mandibular gingiva. (b) Orthopantomogram showing cortical bone erosion
around tooth number 32. (c) The patient was treated with composite resection of the mandible,
bilateral neck dissection (right neck levels I-IV, left neck levels I-III), osteo-cutaneous free bula
ap (FFF), and split-thickness skin graft (STSG) for reconstruction. (d) On the second postoperative week, the patient presented with failed STSG on his lower limb with tendon exposure (red
arrow). (e) Under general anesthesia, STSG area was debrided (tendon exposure noted with red
arrow). (f) 10×15 cm 6-layer Cytal wound matrix was used to reconstruct the ESD, which was
secured with 3/0 chromic sutures. (g) MicroMatrix (1000mg) was mixed with 5CC of saline to
form a paste and applied on top of the Cytal wound matrix. (h) Twoweeks later, granulation tissue
was observed covering the exposed tendon (yellow arrows). Clinical pictures show healing progression at postoperative weeks 4 (i) and 5 (j). Complete tendon coverage with granulation tissue
was achieved (Images courtesy of Dr. Dina Amin)
f
g
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h ij
Fig. 21.4 (continued)
S. A. Wong et al.
ACell Recommended Protocol: Intended forSheet Formulations
1. Prepare the wound bed using standard procedures. Debride as needed to ensure
that the wound is free of exudate and debris.
2. Using sterile technique, open device packaging and remove device from
inner pouch.
3. Prior to insertion, hydrate device with either room temperature sterile saline
(0.9%) or sterile lactated Ringer’s solution. The ACell device must be hydrated
for a minimum of 2min and no longer than 45min.
4. Cut the device to size, ensuring complete wound coverage.
5. Insert device directly into the wound bed.
6. Apply an overlying nonadherent dressing, and secure using preferred methods.
For a wet wound, apply an absorptive dressing, and secure dressings using preferred methods. For a dry wound, apply a hydrogel dressing to retain moisture,
and secure dressing using preferred methods.
ACell Postoperative Management
1. At a minimum, inspect the primary dressing every 7days. During inspection,
remove any exudate, and apply new ACell device to any non-covered areas of the
wound. If a new device is applied, cover it with a new secondary dressing.
2. Change secondary dressings as needed without removing any of the remaining
ACell device that is present on the wound surface.
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3. A caramel-colored gel and a pungent odor will be produced as the ACell device
is resorbed. When washing the wound surface, gently rinse so that the caramelcolored gel remains on the wound surface.
4. Continue the above postoperative management on a weekly basis until the wound
has epithelized or until the desired wound state has been achieved.
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AmnioFix
AmnioFix is an allograft derived from dehydrated human amniotic and chorionic
membranes (dHACM). The high concentration of cytokines and growth factors
found within these extraembryonic tissues signicantly contributes to the wound
healing response elicited by the AmnioFix device [10]. This dermal substitute
comes as a lightweight, opaque, thin collagenous membrane that consists of two
layers: a basement membrane layer and a stromal matrix.
dHACM-based dermal substitutes, such as AmnioFix, are particularly known for
their success in healing chronic, nonhealing wounds, i.e., wounds that either fail to
respond to standard treatment or show <40–50% healing within 3–4weeks posttreatment [10]. This includes classic chronic wounds such as diabetic foot ulcers and
venous leg ulcers. Although the mechanism is not fully understood, it is believed that
the collagen-rich ECM of these dermal substitutes serves as a “sacricial substrate”
that reduces the activity of matrix metalloproteinases (MMPs), which are classically
present in high numbers in many chronic wounds. dHACM-based devices, such as
AmnioFix, have a> 90% success rate in achieving chronic wound closure within
12weeks [10]. Of the dHACM-based products, Amniox has the lowest reported
complication rate, the most common complication being infection [10].
Due to their anti-inammatory and pain mitigation properties, dHACM-based
products have been used to treat inammatory conditions such as plantar fasciitis and
osteoarthritis [10, 30]. Other indications include urothelial tissue repair, management
of chronic neuropathic pain, nerve repair, and cardiac tissue repair following myocardial infarction [10]. Regarding head and neck applications of dHACM-based
devices, they have been successfully used to treat supercial and deep partial-thickness facial burns in both adult and pediatric patients, ocular surface pathologies (ocular burns, symblepharon, pterygium, corneal and conjunctival tumors, persistent
epithelial defects with ulceration), and facial dermabrasions [31–37].
AmnioFix Recommended Protocol
1. Using sterile technique, open the outer pouch and place the inner pouch onto a
sterile eld.
2. Have an assistant slowly peel open the corner of the inner pouch, and present the
allograft to the surgeon. The surgeon should grasp the allograft with sterile
gloves or non-toothed, sterile forceps.
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3. Prior to hydration, cut the allograft to the desired size using sharp scissors.
4. Place the allograft into the surgical site. Be sure to properly orient the allograft
so that the embossed lettering reads correctly from left to right. The orientation
of the allograft may vary depending on the surgical indication.
5. Hydrate the allograft with sterile saline, while it is in the surgical site. This
should be done by applying several drops of sterile saline to the allograft at
1–2min intervals for a period of 5–10min. As the allograft becomes hydrated,
the embossed lettering will begin to fade. It may take several minutes for the lettering to completely fade.
6. Following the recommended 5–10min of hydration, visually inspect and manip-
ulate the allograft to determine whether complete hydration has been achieved.
Some allografts may require additional time.
7. Use absorbable and nonabsorbable suture material and/or tissue adhesives to
secure the allograft to the surgical site.
8. Apply secondary dressings as needed.
S. A. Wong et al.
AmnioFix Postoperative Management
1. Regularly inspect surgical site to determine progression of healing and to moni-
tor for signs of infection.
2. If exudate is present, gently remove and irrigate the wound with sterile saline.
Take care not to disturb the allograft and surrounding tissues.
3. Replace secondary dressings as needed, taking care not to disturb the underlying
allograft and surrounding tissues.
4. Application of a new allograft may be required if the wound does not achieve
complete re-epithelialization.
Conclusion
Dermal substitutes provide an excellent treatment option for head and neck soft tissue reconstruction both when used as the primary reconstructive modality and when
combined with adjunctive procedures. The use of these substitutes has been particularly benecial to medically complex patients, such as those on anticoagulants, as
well as younger patients who would rather avoid two- or three-stage ap reconstructive procedures. In recent decades, numerous dermal substitutes have been developed that vary in their design and composition. However, they all serve to promote
wound healing through the process of constructive remodeling by providing a scaffold that supports re-epithelization, neovascularization, and broblast inltration
while supplying an array of growth factors, cytokines, and chemokines that are
released into the wound site as the dermal substitutes are gradually resorbed and
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