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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_612_Библиотеки_им_академика_М_И_Перельмана
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Tissue expanders are silicone shells that are typically filled with
saline for the expansion process. They may be filled with air initially
to minimize tension on skin flaps12; however; others have found no
benefit to the use of air for the initial fill.13 Under these
circumstances, the air is removed 2 to 3 weeks following surgery and
replaced with saline.
Carbon dioxide has also been described as a fill for some tissue
expanders (AeorForm expanders). These self-expanding tissue
expanders are silicone filled with carbon dioxide when activated by a
remote control. They allow for self-expansion at home, which
decreases clinic visits and travel time, which is ideal for patients who
must travel distances for medical care. The Food and Drug
Administration (FDA) approved these devices for use in the United
States in 2016.14 It is also important to remember that there is a
theoretical and reported risk of self-expansion with expanders filled
with CO2 or air during air travel.15 AirXpanders (the US company that
made these devices) filed for (Chapter 7) bankruptcy in 2019 and is
no longer commercially available.16 Self-swelling hydrogel tissue
expanders have also been described, but are not yet commercially
available in the United States.
17,18
Smooth Versus Textured Expanders
Tissue expander shells can be either smooth or textured. Texturing
helps to hold the expander in position and is especially useful when
the pocket dissection is larger than the expander needed, which is
often seen after mastectomy, or when a shaped expander is used.
Textured tissue expanders were frequently used in breast
reconstruction until the realization that they can be associated with
the development of a rare lymphoma known as breast implant–
associated anaplastic large cell lymphoma (BIA-ALCL).
BIA-ALCL was first reported in 1997.19 Since Brody reported his
case series of BIA-ALCL in 2012,20 the use of textured expanders
has continued to decline. In 2019, the FDA requested that Allergan
issue a voluntary recall of their BIOCELL textured devices.
21
Textured expanders are still available from other manufacturers.
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Tissue Expander Shape
Tissue expanders come in various shapes and sizes that are
instrumental in tailoring the expansion of the local tissue to the
defect. Common choices are a rectangle shape for the expansion of
the forehead or an ellipsoid shape for the scalp. Multiple size options
can also accommodate the size required for the defect. Large
expanders will create a larger flap; however, they cannot be used in
areas with a small donor site. In this situation, multiple small
expanders may be used in separate areas, each with a small donor
site to obtain adequate expansion. Custom expanders are also
available.
Internal Versus External Expansion
In more recent years, external expansion has been used to manage
defects over a relatively short period of time (5-10 days) to directly
close a wound that would have once required alternative closure
options. First described by Blomqvist and Steefnos in 1993,22 the
technique uses multiple single tissue expander units along the length
of a defect. Each unit contains an atraumatic needle, a silicone
string, and two friction stoppers. This technique can be used to close
defects up to 400 cm2. Continuous external tissue expansion uses
the viscoelastic properties of the skin. Mechanical strain from the
device causes cell proliferation and an increase in the surface area
through skin generation of new tissue.
External volume expansion has also been described, specifically
related to breast augmentation.23 While the BRAVA device is no
longer available, the principle and use of external volume expansion
prior to fat grafting still have scientific validity and applications in
plastic surgery.
24,25
Other external expansion systems for the breast
also exist.
26
PRINCIPLES REGARDING EXPANDER
PLACEMENT
When assessing if a patient is a good candidate for reconstruction
using tissue expanders, one should consider multiple factors
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including patient compliance and the ability to return to the office for
weekly expansions, a prior history of radiation therapy (because
higher extrusion rates are common in this setting), as well as the
location of the defect and surrounding tissue. Additional
considerations include extreme caution when using tissue expanders
in smokers and patients with diabetics because of a higher risk of
wound healing complications as well as in the setting of an active
infection.
Once deciding to pursue tissue expansion as a reconstructive
option, one should assess the position of the scars and design
incisions that will not hinder the expansion process. One should also
design placement of the expander to maximize eventual flap rotation.
The site to be expanded should be an area of tissue that matches
the recipient site in color, texture, and hair.
Another consideration when placing an expander is the incision. If
incisions are placed parallel to the direction of expansion, there will
be increased tension on the suture line; incisions placed
perpendicular to the direction of expansion will have less tension on
the suture line. Old scars can also be used as entrance points for
expanders, but areas with previous scars/trauma should be avoided
if possible as they bring higher risk for difficult expansion or
expander extrusion. The space to be expanded should be widely
undermined to accommodate the expander to avoid tension on
suture lines and the incision closed in multiple layers.
To maximize expansion while minimizing scars and time, multiple
expanders may be chosen instead of a single large expander. The
size of the chosen expander should match the defect size. Once the
expander is in place, the port is placed at a distance from the
expander (if a remote port expander is used) to avoid damage to the
implant during the expansion process.
At the time of expander removal, the capsule may be incised to
facilitate rotation or advancement, but should be done judiciously
and under direct visualization as doing so may alter the vascularity of
the flap.27 Upon maximal advancement of the expanded tissue, the
amount of coverage of the recipient site is assessed. If the flap
covers the entire recipient site, all of the tissue/scar to be replaced is
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removed and flap advanced and initially stapled in place before
formal closure. If the flap is discovered to not cover the entire site,
only the part of the recipient site which can be covered is resected
and the flap advanced to cover this area with the expander left in
place under the flap for serial expansion and excision.
PRINCIPLES OF EXPANSION PROCESS
Intraoperatively, a small amount of fluid is placed in the expander. By
placing fluid in the expander at surgery, dead space can be
minimized and folds within the expander can be smoothed. However,
care should be taken not to create tension on the suture line.
7
Expansion may begin as early as 1 week after surgery. Sterile
technique is used. A 22-gauge or smaller butterfly needle is used to
minimize leakage from the self-sealing port. The length of the needle
chosen is appropriate for the tissue being penetrated; for example, a
short 1-in needle may be sufficient for a remote port on the scalp, but
a longer needle may be required for an integrated port breast
expander. The needle is placed at 90° to the access port to
maximize sealing of the valve. The amount of expansion at each visit
is determined by patients’ pain and tissue tolerance, the end point
being tenseness and mild discomfort. The overlying tissue should be
evaluated and checked for capillary refill. Patients may tolerate small
volumes every 3 to 5 days better than larger volumes far apart.
28
COMPLICATIONS
Complication rates with tissue expansion have decreased
significantly with experience and improvements in technique
including incision choice, dissection method, tissue plane placement,
and port placement.29 The majority of complications from tissue
expansion are minor and self-limiting including seroma, widened
scars, expander discomfort, bone resorption, and neuropraxia.
Langdell et al30 found that complication rates were highest in
expanders used in genital reconstruction followed by the lower
extremity. Another study on tissue expansion found complication
rates as high as 39%; however, the final outcome was not affected.
31
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When these complications are encountered, the expansion process
can often be salvaged and resumed. And when a complication
occurs at the end of the expansion process, there may be enough
expansion to allow for removal of the expander and completion of
the reconstructive plan.
A seroma may be safely drained with aspiration with the injection
needle at time of expansion with indwelling port expanders by
aspirating on withdrawal once the needle is out of the self-sealing
port. Alternatively, a seroma can be drained under ultrasound
guidance. Major complications, which could result in return to the
operating room, include hematoma, infection, expander exposure,
iatrogenic rupture of the implant, or overlying tissue compromise.
Large hematomas should be evacuated so as not to compromise the
tissue or act as nidus for infection.
Early infections are the result of bacterial introduction in the
perioperative period. There should be no open wounds at the time of
expander placement. Areas of high lymphatic drainage such as the
neck, groin, or extremities after trauma should be drained and
treated with antibiotics while the drain remains in place. Late
infections are more commonly the iatrogenic introduction of bacteria
during expansion, making sterile technique important. Erythema may
occur over all expanders because of tension on skin, but erythema
associated with fever, chills, warmth, and pain should have high
degree of suspicion for infection. If caught early, oral antibiotics may
ameliorate the infection, but one should have a low threshold for IV
antibiotics and/or a washout and placement of new expander Versus
leaving the expander out for 3 to 4 months. If the infection occurs
late in the expansion process, the expanded skin can frequently be
advanced fully, and the reconstruction salvaged.
Mechanical failure of the expander or iatrogenic rupture will
require replacement of the device if more expansion is needed.
Exposure of the expander can result from poor tissue quality,
infection, overaggressive or rapid expansion, improper placement, or
suture line failure. Early exposure is usually best managed with
removal of the expander and return for replacement in 3 to 4 months.
Partial or late exposure may be managed with antibiotic cream over
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the exposed implant and multiple rapid fillings to still obtain
successful skin rotation.
USE OF TISSUE EXPANDERS
Expanders can be used to treat many plastic surgery problems—
including burns, congenital nevi, conjoined twin separation, breast
reconstruction, abdominal wall reconstruction, and traumatic injuries.
Many may consider serial excision for the treatment of some of these
lesions or scars as well; however, if a lesion is not able to be excised
in three excisions or fewer, then a tissue expander should be used.
27
Head and Neck
Scalp
Expansion is the ideal solution for defects of the scalp.29 Because no
other tissue of the body mimics the scalp, utilizing adjacent scalp
tissue is first-line treatment. Defects of the scalp and alopecia can
occur from burns, tumor resection, congenital lesion removal,
trauma, infection, and radiation injury. Tissue expansion can also be
used in conjunction with scalp reduction for male pattern baldness,
but is less common today with advancements in hair transplantation.
Expansion may be used to cover defects involving up to 50% of
scalp without significantly thinning the hair density.32 The scalp is
durable and reliable because of its robust vascularity and the
incorporation of one of the dominant occipital or superficial temporal
vessels into the designed flap. Incisions are chosen along the
planned rotation flap, often based on one of these vessels. For large
defects, multiple small expanders may be more easily placed than
on a large expander.
Positioning of the head during placement should be carefully
planned to avoid inadvertent thinning of the scalp as it is dissected
off the round skull. Expanders are placed in a subgaleal plane, and
the pocket is created with blunt dissection to minimize trauma to the
overlying tissue. Galeotomies may allow for easier and faster
expansion but have a greater risk of expander extrusion. The
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inflation ports are placed away from the expanders in the forehead or
scalp vertex. Expansion of the scalp becomes less painful over time
and is estimated to take 6 to 8 weeks.
Upon removal of the expander, capsulotomies may be carefully
performed to improve the reach of the flap but with care not to injure
underlying vessels. Expansion will cause skeletal remodeling and
thickening of subcutaneous tissue at the expander edges as well as
dog ear formation on advancement of the flaps. All of these do not
need to be addressed as they are temporary and resolve in 3 to
4 months.
Prolonged placement of an expander in the scalp may result in
bony deformation of the skull; however, no permanent deformation
has been reported, specifically in children.
27
Forehead
Expansion of the forehead allows for reconstruction of the subunit
without disruption of the anterior hairline while maintaining symmetric
brow position. Expansion and advancement of forehead flaps can be
expected to reconstruct defects up to 70%. Defects less than 25%
are managed with serial excision, and defects greater than 70% may
require an expanded full-thickness skin graft or free flap as a subunit
replacement.33 Forehead expansion is used to lengthen the forehead
of patients with craniofacial anomalies who have a low hairline. The
expanders are placed through a scalp or hairline incision beneath
the frontalis muscle. Forehead expansion is often used in
conjunction with scalp expansion to maintain the anterior hairline.
Nose
Major defects of the nose are treated with pre-expanded forehead
flaps to produce an adequate amount of similar color and texture
tissue for coverage while allowing for primary closure of the donor
site. The expanded flap can be used for both lining and skin
coverage and is supported by underlying bone/cartilage support to
avoid distortion.
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Face and Neck
Principles of reconstruction of the face revolve around subunit
planning with attention to function, symmetry, and similar tissue
characteristics. The lateral face and neck tissue are similar in skin
texture, sebaceous gland density, skin thickness, and hair
distribution, making them ideal for aesthetic subunit coverage.
34
Defects of the cheek are commonly reconstructed with adjacent
tissue using a Mustarde rotation flap. When the flap alone is not
enough for coverage, expanders are placed through a preauricular
incision, superficial to the platysma—this maximizes flap rotation and
decreases risk of injury to the marginal mandibular nerve. Incision
lines upon advancement should follow the subunit along the
infraorbital rim, nasolabial fold, and preauricular line. Once expanded
and advanced superiorly to cover the cheek, the flap must be
secured to deep muscle or bone to avoid distortion of the lateral
commissure or lower eyelid with retraction of the flap.
Ear
Expansion of adjacent skin may be needed for partial or total ear
reconstruction. It is performed with expansion of non–hair-bearing
skin through an incision in the posterior hairline.
35,36
Trunk
Expanders in the trunk and abdomen can be either placed above the
fascia, subfascial, or between muscle planes in the abdomen and
back. The trunk tolerates placement of larger expanders that can be
quickly expanded. However, multiple smaller expanders around a
defect may be better tolerated by the patient because there may be
less discomfort and deformity. Expansion of the buttock and back
area may be poorly tolerated because of interference with daily
activities. Serial expansions with reinsertion of the expander at the
time of advancement and inset are utilized to allow for coverage of
large defects.
Breast
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A common use for tissue expansion is in breast reconstruction—
whether after mastectomy, for burns, or for congenital breast
anomalies.
Despite the increased use of direct-to-implant and autologous
tissue reconstruction, tissue expanders remain an important option in
breast reconstruction. This is especially true in delayed
reconstruction for a patient desiring implants, where the skin muscle
may need to be expanded to accommodate the implant and improve
the aesthetic outcome. Tissue expander to implant reconstruction is
a safe, reliable, simple procedure, which most commonly requires a
two-stage process. The only exception is the SPECTRUM implant by
MENTOR, an expander that becomes the definitive implant upon
removal of the remote port, which can be done in the office. The
patient is seen weekly for expansion until the desired size is
achieved. The second procedure for removal of expander and
placement of the definitive implant is a simple outpatient procedure
at which time adjustments can be made to the pocket with
capsulotomy and capsulorrhaphy techniques, as well as fat grafting,
all of which can be performed to improve the aesthetic outcome.
Immediate expander reconstruction adds minimal time to the
mastectomy operative time, does not require additional
hospitalization, and is more commonly being performed as an
outpatient procedure.
The use of tissue expanders in reconstruction began in a
subcutaneous plane,5 which resulted in firm, round breasts with a
high rate of implant extrusion. Because of these issues, surgeons
began placing the expander in a partial submuscular plane—this
included placement under the pectoralis major only with no coverage
of the lateral expander or release of the inferior edge of the
pectoralis muscle, which was then sutured to the skin to cover the
superior aspect of the expander. For complete coverage of the
expander and separation from the mastectomy wound, a total
submuscular plane was used, involving the pectoralis major,
pectoralis minor, serratus, and rectus muscles. Total submuscular
coverage led to a painful expansion process and high-riding
expanders with less-than-ideal stretch of the lower pole.
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The introduction of acellular dermal matrix allowed for more
secure placement of the expander in a partial submuscular plane—
this technique also decreased the pain of expansion when compared
with a total submuscular plane, while supporting the lower and lateral
poles of the expander and allowing for more aesthetic expansion of
the lower pole. Prepectoral placement of implants with acellular
dermal matrix coverage has decreased the need for tissue
expanders in breast reconstruction. However, they are still used in
immediate reconstruction on patients with poor tissue vascularity or
thin skin flaps, requiring either placement in a submuscular plane or
minimal inflation initially to avoid pressure on the skin.
Congenital anomalies requiring expansion for the soft tissue of the
breast include amastia, unilateral breast hypoplasia, Poland
syndrome, or tuberous breast deformity. Other causes of breast
asymmetry include burn, trauma, or iatrogenic injuries to the breast
bud altering growth. Tissue expansion is especially helpful in young
patients with asymmetry as it provides a method to incrementally
expand the affected breast as the normal breast grows.
Extremities
Congenital abnormalities, tumor, or trauma of the extremities can
result in defects requiring expansion and flap advancement. Tissue
expansion of the extremities is known to have higher complication
rates than tissue expansion in other areas.
30,37
Another review by
Wang et al38 also found that expanders used in the lower extremity
had some of the highest complication rates.
Multiple expanders are advantageous for less distortion of the
extremity, less disruption of normal activity, and more rapid
expansion. The soft tissue of arms and legs expands most readily in
a radial direction. Rectangular, crescent, or oblong expander shapes
are recommended. The dorsum of hand and foot may require
smaller custom implants.
The capsule can be beneficial for adding glide over joints and
tendons.
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