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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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Other techniques to improve blood flow to a flap include
supercharging or turbocharging the flap (Figure 4.8). These are
two related but distinct techniques. Supercharging a flap augments
the vascular flow with an unrelated source vessel. Turbocharging a
flap siphons off flow from a vessel already intrinsic to the flap
territory, usually to distribute blood to an otherwise more ischemic
portion of the flap.
18
FIGURE 4.8 A supercharged and turbocharged flap.
Green: Supercharging from an external blood supply;
Blue: Turbocharging by connecting an inherent blood
supply.
For more complex defects, the reconstructive surgeon can look to
compound flaps , which consist of multiple tissue components
linked together to facilitate simultaneous transfer to a recipient site.
19
Composite flaps are the most commonly used compound flaps and
consist of multiple tissue types supported by a singular vascular
source. For example, myocutaneous flaps such as latissimus dorsi
flaps carry both muscle and skin based on the same pedicle, and
similarly osteocutaneous flaps such as fibula flaps carry both bone
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and skin on one pedicle. For complex defects that require multiple
kinds of tissue, composite flaps are necessary. Conjoined flaps are
flaps that are connected through a common physical boundary but
are too large to be maintained on a single vascular pedicle and thus
maintain their independent blood supply.19 Conjoined flaps can be
used to harvest extremely large flaps to fill large defects. A large
TRAM flap harvested on both deep inferior epigastric arteries would
be considered a conjoined flap. With the advent of the perforasome
theory, any flap harvested on multiple perforators could be
considered a conjoined flap. Chimeric flaps , also known as
polyflaps, consist of multiple otherwise independent flaps that can be
harvested by tracing their pedicles to a single source vessel. The
most common source of chimeric flaps is the subscapular vessel
system, as it feeds independent pedicles to fascia, muscle, skin, and
bone.
19
Method of Transfer and Movement
After determining the amount and type of tissue to be replaced in the
defect, an important question for the reconstructive surgeon
becomes: “How will I get the tissue to this defect?” In general, flaps
can come from local, regional, or distant tissues. When describing
local flaps, the method of transfer is frequently used to describe the
flap options (Table 4.1). Regional flaps come from further away and
thus typically require larger movements, but can still be broadly
categorized into rotation, advancement, and transposition. Local
flaps can be islandized on a small perforator; however, more
commonly, these islandized flaps are regional (Figure 4.9). Distant
flaps typically harvest a free flap. However, with enough creativity as
well as freedom of movement of either the donor or recipient site,
distant tissue can be attached to a recipient site while still attached
to its site of origin, allowed to heal, then detached in a second stage.
Groin flaps to cover the hand are a still used example of these tubed
flaps. Some of the earliest descriptions of nasal reconstruction by
Branca and Tagliacozzi in the 15th and 16th centuries involved the
use of a distant tubed arm flap from the nose (Figure 4.10).
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TABLE 4.1. CLASSIFICATION OF FLAPS BY MOVEMENT
TYPE
Flap
Movement
Subtypes Images
Rotation Rotation
FIGURE 4.1
Rotation flap.
FIGURE 4.2
Rotation flap. A.
Defect; B. Design of
rotation flap; C. Inset
and Closure.
Advancement V-to-Y
Keystone
Bipedicled
FIGURE 4.3 V-to-Y
advancement.
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FIGURE 4.4
Karapandzic bilateral
musculocutaneous
advancement flaps.
A. Defect; B.
Advancement and
inset.
Transposition Z-plasty
Rhomboid
Bilobed
FIGURE 4.5 Z-
plasty Transposition
flaps.
FIGURE 4.6
Rhomboid
transposition flap. A.
Planned excision with
flap marking; B.
Defect with flap; C.
Flap transposed and
inset.
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FIGURE 4.9. An islandized thoracodorsal artery
perforator flap for axillary reconstruction. A. Defect; B.
Islandized flap, arrow marks perforator; C. Flap inset and
closed.
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FIGURE 4.10 Sixteenth century depiction of a tubed flap
from the arm to nose. (From Tagliacozzi G. On the surgical
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restoration of defects by grafting. 1597. Wellcome
Collection. Public Domain.
https://wellcomecollection.org/works/h8dvadad)
Manipulation
If necessary, flaps can be manipulated prior to transfer and can be
classified based on the techniques used to do so. Tissue expansion
is a useful tool that allows for greater tissue coverage on the same
vascular pedicle. The stretch of expansion induces both mechanical
and biologic creep, which increases cellular proliferation and
angiogenesis. Dermis becomes thinned, epidermis thickens, and
overall the skin is thinner.
21
As discussed previously in the chapter, surgical delay involves
division of a portion of the vascular supply at the initial stage,
stimulating vessel dilation across choke points and improving flow
across the remaining blood supply.
Prefabrication and prelamination are manipulation terms that
are frequently confused and conflated. Prefabrication as a term was
first used in 1981 by Shen and specifically refers to
neovascularization of a segment of a tissue through implantation of a
vascular pedicle.22 Second stage will then transfer the flap based on
that same pedicle. Prelamination describes implantation of a device
or other tissue types in the flap prior to transfer without any
manipulation of blood supply. Commonly, this is employed to implant
cartilage grafts in a flap prior to reconstruction in the head and neck
region.
23
FLAP DESIGN AND CHOICE
Considering all the classifications mentioned allows us as plastic
surgeons to select the best flap to suit the defect and patient.
Ultimately, the goal will always be to maximize the functional and
esthetic result of both the recipient and donor site.
Evaluation of Defect
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Before planning any sort of reconstruction, the first step is to decide
what is or will be missing. With improved screening and imaging
modalities, the ideal reconstructive plan begins well before the defect
is created. More accurately designed flaps with the use of adjunct
modalities will be discussed later in the chapter. While this is the
ideal, there will always be situations in which a surgeon encounters a
defect they have never seen before. When evaluating a defect, the
reconstructive surgeon should determine what tissue is lost. This
should be a detailed, thoughtful analysis that considers not only type
of tissue but also quality, for example, recognizing skin loss and also
skin color, thickness, and hair-bearing status. After determination of
tissue loss should come the determination of the loss of function,
which may include functional muscle sacrifice, loss of tooth-bearing
segments of bone, or loss of lymphatic drainage. Looking more
holistically, evaluation of a defect should additionally include
evaluation of the overall health status of the patient. Not every
patient is healthy enough to undergo a lengthy free flap procedure,
and certainly, individual patient factors such as weight, diabetes,
smoking status, and clotting disorders will affect the success of any
given reconstructive option. If risk factors to the patient or flap are
high, it is prudent to go with simpler, shorter reconstructions.
It is important to ensure that the defect is ready for reconstruction
prior to transfer of a flap. The wound should be adequately debrided
of necrotic tissue, excess granulation, and otherwise nonviable
material. If there is sign of infection, the wound should be irrigated
copiously, and thought should be given to delaying reconstruction
until infection is fully cleared. Similarly, for oncologic defects, if there
is concern for pathologic margins, the wound should be temporized
with dressing or allograft skin substitute. When margins are
confirmed to be clear, final flap reconstruction can proceed. If
planning for free flap, it is also essential to identify anatomically
proximate arterial and venous supply of sufficient caliber that will be
able to sustain the inflow and outflow of the flap. If these are not
identifiable, then consideration can be given to performing vein grafts
or arteriovenous loop to reach a more a distant vessel set.24 Poor
planning and inadequate preparation of the recipient site can lead to
reconstructive failure despite a healthy and viable flap harvest.
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When the surgeon is ready to start designing the flap, accurate
measurements must be taken of length, width, and depth, which can
be achieved with simple measurement with a ruler or the use of
template that can then be transferred to the donor site.
Flap Selection
Evaluation of the defect as previously mentioned will help guide flap
and donor site selection. Given their proximity to the wound, local
flaps typically have the best tissue quality match with regard to skin
color and thickness; however, depending on the size and location of
the defect, especially in a high-demand region like the face, local
tissue may be inadequate. If local flaps are found to be lacking,
broadening the search to regional and distant flaps significantly
increases the options available. When faced with such a large
selection, looking to our flap classifications can help filter through
flaps that will be helpful. First, tissue classification should filter out
any flaps that do not contain the requisite tissue types. Of the flaps
that contain the needed tissue, the surgeon should consider whether
the tissue is of similar quality. For example, for flaps that contain
skin, this would include consideration of color, thickness, hair growth,
and texture; for bony flaps, considerations of bony strength and
adequacy of bone stock for potential implants are important.
Secondly, flap blood supply will help guide selection. For pedicled
flaps, the vascular leash of the selected flap must allow for the flap to
reach the defect. Consideration of free flaps should include the
caliber and length of the pedicle, which should match the caliber of
the recipient vessel as best as possible and allow for the flap to
reach the defect from the site of anastomosis.
Thirdly, if flap manipulation is required, then this should be
planned around the site selection. Compound flaps like chimeric
flaps have blood supply requirements and usually come from the
subscapular or circumflex femoral arterial systems. Conjoined flaps
require a body of tissue that is supplied by two major blood vessels.
Selection of the donor site should consider ease of access during
surgery; positional changes should be avoided if possible.
Furthermore, design of the flap should consider the residual defect
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after harvest. Most commonly, these defects are closed primarily,
and scars should be designed to sit within resting skin tension lines.
Hiding scars within clothing lines is also ideal. If a muscle flap is
needed, functional loss from harvest of the flap should be discussed
and considered; if possible, muscles with redundant function should
be chosen.
Adjunctive Tools
Technology has availed the reconstructive surgeon with numerous
adjuncts to assist in flap design and selection. Preoperatively, these
tools are helpful for evaluating the blood supply to any planned flap.
One of the simplest methods is through handheld or ultrasound
doppler, which will allow localization of blood vessels. For most
perforator evaluations, an 8- to 10-MHz probe should be used.
Lower frequencies have too much soft-tissue penetration and may
be capturing deeper vessels that are not relevant.25 More
complicated reconstructions may warrant CT angiography to further
visualize all of the vessels. This has become popular for evaluating
deep inferior epigastric perforators, lower extremity perforators, and
lower extremity runoff to evaluate donor vessels.
26
CT scan and MRI images have previously been evaluated as 2D
slices either in the axial, sagittal, or coronal planes, and it is
incumbent upon the surgeon to synthesize these into a mental 3D
picture. Advances in software processing now allow us to build
complex sectioned 3D models from these 2D images that can be 3D
printed as guidance models or even viewed in virtual reality (Figure
4.11). Additionally, these models can allow for customized patient-
specific surgical guides and implants, which can make flap elevation
and inset more exact and seamless.
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