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CHAPTER24 Perineal and genital burns
Delayed reconstruction
Perineum
• Most commonly cicatricial contracture between proximal inner thigh
and perineum, or between genitalia and anus
• Reconstruction depends upon extent of scar and quality of adjacent
tissues
• May enable excision and direct closure, or require local fasciocutaneous
aps (triangular/ rhomboid/ lotus), groin, or anterolateral thigh aps
Male genitalia
• Extent of scarring may not be apparent in accid state
• If Buck’s fascia spared, defects can be resurfaced with full thickness skin
graft or split skin graft with dermal matrix
• If Buck’s involved, defects require ap coverage
• Testicular burns are rare due to multiple layers of fascial coverage. If
signicant scrotal debridement necessitates ap coverage, muscle aps
may be less suitable as resultant higher testicular temperatures may
inuence spermatogenesis
• Requirement for penectomy and phalloplasty is thankfully very rare
Female genitalia
• Local skin aps and grafts (±fat transfer) can be used for labial
reconstruction
• Larger defects require ap reconstruction
• Vaginal and introital stenosis may limit options for normal vaginal
delivery
Further reading
Angel C, Shu T, French D, etal. Genital and perineal burns in children:10years of experience at a
major burn center. Journal of Pediatric Surgery 2002;37:99.
Bordes J, Le Floch R, Bourdais L, etal. Perineal burn care:French working group recommendations.
Burns 2014;40:655.
Huang T. Management of burn injuries in the perineum. In Herndon DN (ed.) Total burn care, 3rd
edn. Philadelphia:Saunders Elsevier, 2007.
Michielsen DP, Lafaire C. Management of genital burns:a revie w. International Journal of Urology
2010;17:755.
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Chapter25
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Skin substitutes
Purpose and development of skin substitutes 204
Advantages of skin substitutes 204
Disadvantages of skin substitutes 204
Skin substitutes for temporary wound cover 206
Skin substitutes for wound closure 208
Further reading 212
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CHAPTER25 Skin substitutes
Purpose and development ofskin
substitutes
Skin substitutes are a heterogeneous group of wound coverage materials
that aid in would closure and replace the functions of the skin. They were
developed as an adjunct or alternative to autografts, which remain the current gold standard for the treatment of burns.
Advantages ofskin substitutes
• Provide immediate wound cover— temporary or permanent
• Mechanical barrier to infection and uid loss
• Optimize conditions for healing and keep the wound bed moist
• Stimulate the wound bed and promote new tissue growth/ provide a
neodermal base
• Can minimize scar contraction
• Available in large quantities
Disadvantages ofskin substitutes
• Expensive
• Can be dicult to store with short half- life
• Learning curve for clinical application and use
• Ethical issues may limit their use in certain religious groups
• Risk of cross- infection (potentially with allografts and xenografts)
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DISADVANTAGES OFSKIN SUBSTITUTES
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CHAPTER25 Skin substitutes
Skin substitutes fortemporary
wound cover
Biobrane
Dow– Hickham, Sugarland, TX, USA.
Type
Temporary biosynthetic dressing.
Features
• Bilaminate membrane composed of a thin outer silicone membrane
(epidermal analogue) with a knitted nylon mesh
• Porcine type 1 collagen is incorporated into the silicone and nylon
components
• The chemically bonded collagen promotes adherence to the burn
wound with a brin bond
• The semipermeable membrane allows drainage of exudate from the
wound surface
• Prevents evaporative uid loss and the development of infection
Applications
• Temporary coverage for partial thickness burns that are expected to
heal within 14days. The dressing adheres to the wound and detaches as
the burn heals
• Temporary coverage for freshly excised full- thickness wounds
• Donor site coverage
• TENS (toxic epidermal necrolysis)
Advantages
• Can obviate painful dressing changes, reduce inpatient treatment and
length of stay in partial thickness burns
• Pain relief and accelerated healing when used to cover donor sites
• Specic anatomical designs available, eg. gloves
Drawbacks
• Non- adherence to the burn wound can lead to accumulation of uid
and subsequent infection. Any uid accumulations and infection should
be released
• Staphylococcal toxic shock syndrome in children from pooling of
exudate underneath the dressing has been reported
TransCyte (formerly Dermagraft)
Advanced Tissue Sciences, La Jolla, CA, USA.
Type
Temporary biosynthetic dressing.
Composition
• Consists of a polymer membrane and neonatal human broblasts
cultured on a nylon mesh in vitro. Prior to cell growth, the nylon mesh is
coated with porcine dermal collagen and bonded to a silicon membrane
• The broblasts proliferate within the nylon mesh during the
manufacturing process and secrete dermal collagen, growth factors,
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SKIN SUBSTITUTES FORTEMPORARY WOUND COVER
glycosaminoglycans (GAGs), and bronectin to aid wound healing.
Cryopreservation renders the broblasts non- viable
Applications
• Temporary covering for excised full thickness burns prior to autografting
• Temporary coverage for partial thickness burns that do not require
autografting. The dressing adheres to the wound and detaches as the
burn heals
• Partial- thickness facial burns:the pliable dressing easily conforms,
rapidly adheres and integrates to protect the wound. Decreased pain,
accelerated epithelialization, and healing over conventional topical
therapies has been suggested
Drawbacks
• Cumbersome storage and pre- use preparation:stored frozen
between– 70°C and– 20°C and can be thawed no longer than 2 hours
before use. If stored correctly, it has a shelf life of 18months
• More expensive than biobrane but no real benet has been
demonstrated over Biobrane in partial thickness burns
Allograft
Type
Cryopreserved cadaver skin.
Features
• Second choice following autograft
• Takes readily and provides durable coverage
Applications
• Denitive closure with the allograft– autograft sandwich
technique:widely meshed autograft covers the wound bed to provide
permanent closure. An allograft (2:1 mesh) is laid over the autograft to
provide a temporary protective physiological barrier
• Estimating usage:0.5cm2 allograft/ cm2 burns <40% TBSA, and 1.82cm2
allograft/ cm2 burn for 40– 80% TBSA
• Temporary biological dressing for donor sites, allowing them to heal
prior to reharvesting
Drawbacks
• Expensive
• Requires storage at– 40 to– 80°C
• Cryopreservation decreases viability by 54% to 73% of fresh tissue
• Poor barrier function
• Risk of disease transmission despite screening of tissue donors and
testing for bacterial and viral contamination
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CHAPTER25 Skin substitutes
Skin substitutes forwound closure
Alloderm
LifeCell Corporation, Branchburg, NJ, USA.
Type
Cryopreserved acellular dermal allograft.
Features
• Split- thickness skin grafts are obtained from human cadavers (the
donors are screened for transmissible diseases)
• The epithelial components and dermal cellular components are
removed, the residual dermis is treated with a proprietary detergent to
inactivate viruses, and then cryopreserved
• Provides a non- antigenic upper dermal scaold consisting of basement
membrane proteins and type IV and VII collagen
• Available in a variety of thicknesses
• Rehydrated in a sterile saline solution immediately before use
• Following application to a wound bed, it is repopulated by host cells,
revascularized and incorporated into the tissue. It functions as a
template for dermal regeneration
Applications
• Thin layer of alloderm is used to cover acutely excised burn wounds or
incisional releases in combination with simultaneous placement of an
overlying thin, split- thickness autograft
Advantages
• Reported to have good ‘take’ rates
• When compared with the use of split- thickness autograft alone for full-
thickness wounds, it is thought to result in less scarring and to provide
more pliable soft tissue cover
Drawbacks
• Expensive
• Relatively marginal benet
Integra
Integra LifeSciences, Plainsboro, NJ, USA
Type
Dermal analogue.
Features
• Bi- laminar structure
• Supercial layer of fenestrated silicone membrane provides a temporary
epidermal barrier function, and protection against uid loss and bacterial
colonization
• Deep layer composed of cross- linked bovine collagen and chondroitin-
6- sulphate, provides a biodegradable framework
• Once applied to the wound, the deep collagen layer promotes
the migration of broblasts and endothelial cells and becomes
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SKIN SUBSTITUTES FORWOUND CLOSURE
bio- integrated in the wound. Avascular neodermis is formed in
approximately 2– 3 weeks
• After integration 2– 3 weeks later, the silastic layer is removed and an
ultrathin split- thickness skin graft is applied in the second stage
Applications
• Commonly used to provide immediate cover in the treatment of
major burn where a paucity of available donor area precludes early
autografting. Frequent thin, split- thickness grafts can be reharvested for
staged reconstruction in extensive burns
• Used for burn contracture release
• Pliable soft tissue cover over joints and tendons where aps may be too
complex and bulky, and skin grafts alone would provide poor aesthetic
and functional result
• Integra may provide a well- vascularized neodermis and allow skin
autografting without the need for complex reconstruction where
there is poorly vascularized tissue with exposure of bone, cartilage, or
tendons
• Integra combined with VAC therapy may accelerate integration and
vascularization, shorten the time between the rst and second stages,
reduce length of hospital stay, minimize dressing changes and remove
uid from under the matrix sheet
Advantages
• Long shelf- life
• Available in large amounts without any preparation
• Can provide thin soft tissue cover without the bulk of a ap
• Allows good functional and aesthetic result compared to split skin
graft alone
• May provide a more durable and superior long- term aesthetic result
with less hypertrophic scarring and pruritus compared to those burns
treated by conventional excision and grafting alone
Drawbacks
• Requires a two- stage procedure and extended hospital stay
• Time- consuming dressing changes required until healing is complete
• Dermal matrix ‘take’ can be poor and become infected
• Haematoma or seroma can accumulate under the matrix
• Steep learning curve
• Expensive
Matriderm
Skin and Health Care AG, Billerbeck, Germany.
Type
Bovine dermal substitute features
• Structurally intact matrix of bovine type Icollagen with elastin
• Matrix serves as a support structure for in growth of cells and vessels
• Elastin component improves the stability and elasticity of the
regenerating tissue. As the healing process advances, broblast lays
down the extracellular matrix and the matrix resorbs
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CHAPTER25 Skin substitutes
Applications
• Useful in functional areas, eg. over joints and tendons, where elasticity,
pliability and stability is desirable
• Can provide a thin, pliable, and aesthetic pleasing skin cover
Advantages
• Allows one- stage reconstruction with synchronous application of
dermal substitutes and skin grafts
• Thought to reduce wound contracture and increase elasticity of skin
and provide a more pliable and durable skin cover than using a skin
graft alone
• As reconstruction is a single stage, there is less risk of infection,
fewer dressing changes and potentially shorter hospital stay required
compared to that of Integra
• Available in 1mm and 2mm thickness, in various sizes
Drawbacks
• Expensive.
Apligraf (Graftskin)
Organogenesis, Canton, MA, USA.
Type
Bi- layered living skin equivalent.
Features
• Engineered collagen- based substitute containing viable cells
• Designed to mimic the structure of the human skin
• Bi- layered:the supercial layer consists of a cornied epidermal layer of
neonatal allogeneic keratinocytes and the deep layer (dermal analogue)
combines living neonatal allogeneic broblasts in a gel of type Ibovine
collagen
• Not attached to any polymer membrane
Applications
• Can be used as a temporary covering over meshed expanded autograft
for excised burn wounds
Advantages
• Apligraf combined with autograft is thought to produce more
favourable results than autograft only with more pliable soft tissue cover,
less scar formation, pigmentation, and improved texture of the graft
Drawbacks
• Currently the most sophisticated and most expensive commercially
available tissue- engineered product
• The material is supplied to a given date and has to be applied ‘fresh’
• Requires careful handling and short- term storage:shelf- life of just 5days
at room temperature to ensure viability of the cells in the two layers
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SKIN SUBSTITUTES FORWOUND CLOSURE
Cultured epithelial autograft (CEA)
Features
Sheets
• Requires a full thickness skin biopsy of several square centimetres:a
2cm2 biopsy produces a 1.8 m2 conuent sheet ve cells thick
• The sheets of epithelial cells, about six cells thick, are attached to a
petroleum- impregnated gauze carrier to facilitate the physical handling
of the otherwise extremely fragile, thin sheets
• 3 weeks’ preparation time
Suspension
• Fibrin glue suspension takes less time to process but cells are
less mature
• Used either in combination with widely meshed split skin graft or for
donor- site re- epithelialization
Advantages
• Autologous cells
• Only a small biopsy needed
Disadvantages
• Expensive
• Long preparation time of 3– 5 weeks
• Provides very thin and fragile skin cover and the resulting epithelium is
unstable. Although initial graft take is good, there may be late graft loss
with spontaneous blistering and infection many months after grafting
• The skin graft may be more susceptible to infection and contractures
• Ahigh degree of coordination is required between the burn unit
and laboratory to use the cultured epithelial autograft sheets at their
optimum
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