Phẫu Thuật Tạo Hình (Tập 1): Nguyên Lý Cơ Bản – Neligan (2018)

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CHAPTER 24 • Principles and techniques of microvascular surgery
The ring–pin device is a simple, efficacious, and faster
technique of anastomosis and has the added advantage of not
disturbing the intima in the anastomosis. It is the most suc-
cessful and commonly used coaptation device. It has yielded
excellent patency rates of up to 100%, even in fields that have
been previously irradiated.51–53 The rings come in a variety of
sizes from 1 to 4 mm in diameter, allowing the coaptation of
vessels ranging from 0.8–4.5 mm with a maximal wall thick-
ness of 0.5 mm, and the device is suitable for both end-to-end
and end-to-side anastomosis. It is contraindicated in periph-
eral vascular disease, areas with ongoing radiation therapy,
active infection, concurrent diabetes, and corticosteroid
therapy.
In an experimental comparison of venous anastomosis
with use of this device, the sleeve technique, and the standard
end-to-end technique, patency rates were 100%, 80%, and
95%, respectively. In an analysis of 1000 consecutive venous
anastomoses with this method in breast reconstruction, Jandali
et al.54 reported an anastomotic time of 2–6 minutes with a
99.4% patency rate. No total flap losses were encountered. It
has also been used effectively in end-to-side anastomosis of
veins in head and neck free-flap reconstruction, with 99–100%
patency.53,55 To resolve the problems of a permanent rigid ring,
an absorbable anastomotic coupler was developed and has
been used experimentally and clinically, achieving patency
rates of 92.9–100%56–58 and 95%, respectively.59 The ring was
completely absorbed at 70 days to 30 weeks after anastomosis.
Although used mainly for venous anastomoses, the mechani-
cal coupling device has been also used successfully in per-
forming arterial anastomoses, with up to 100% patency
rate,60–63 proving to be expeditious, safe, and reliable. Contra-
indications of using this device on arterial anastomosis include
thick-walled vessels that do not adequately evert, diameter
discrepancies of more than 1.5 : 1 ratio, nonpliable vessels
stiffened by prior radiotherapy or calcification, and any artery
less than 1.5 mm in diameter.60
The nonpenetrating microvascular stapler, available as a
disposable device (VCS clip applier system), reported by
Kirsch et al.,64 uses nonpenetrating titanium clips applied in
an interrupted, everting fashion. The clips come in four sizes,
ranging from 0.9 to 3.0 mm, and demonstrate a reduced
anastomotic time and higher patency rate. In an end-to-end
anastomosis, two stay sutures are first placed at 180° to facili-
tate the eversion of vessel walls during clip placement and a
special everting forceps and experienced assistant are needed.
In an end-to-side anastomosis, four sutures are recommended
with sutures at the heel and toe and two stay sutures at the 3
and 9 o’clock positions. Yamamoto et al.65 reported clinical use
of these staples with a mean anastomosis time of 12 minutes
and Cope et al.66 reported a 100% patency rate of 153 anasto-
moses of both veins and arteries. A comparative scanning
electron microscopic study demonstrated no major differences
between sutured and stapled anastomoses.67
All anastomotic devices are essentially for use on healthy
vessels only; the veins should be pliable, the arteries
soft to allow eversion,52 and the vessel ends minimally
size-discrepant.
Other nonsuture methods
Methods to glue or to weld a union of two vessels seem
attractive and have been intensively studied experimentally.
Microsutures
Buncke47 described making his first microneedle by drilling a
hole in a 75-mm stainless steel wire. This needle held a single
strand of silk and was used to replant a rabbit’s ear by anas-
tomosis of 1-mm vessels. Soon a commercially available
needle was developed by Acland,48 working with the
Springler-Tritt company.
Since then, microsurgical sutures have been available in
combinations of different materials, suture sizes (8-0 to 12-0),
tensile strengths, and needle configurations. The microsuture
is considered to be the standard means of vascular anastomo-
sis. The most widely used sutures are 9-0 monofilament nylon
on a 100-µm curved needle and 10-0 nylon on a 75-µm needle.
The choice is usually made based on the vessel wall thickness
and diameter, with 9-0 sutures used for vessels of 2 mm or
more in diameter and 10-0 for those between 1 and 2 mm in
diameter. Smaller suture–needle combinations are available
but reserved for use by experienced microsurgeons with very
fine instruments, for very distal fingertip replantations, anas-
tomoses in small children, and in lymph vessel anastomosis.
Microneedles are typically shaped as three-eighths of a circle
but are also available as a half-circle or straight (rarely used
now), with round, tapered, or spatula-shaped tips to prevent
damage to the fragile vessel wall. The commonest suture used
in microsurgery is nonresorbable nylon which has low tissue
reactivity and knot-holding ability, although polypropylene is
preferred by some as it slides and handles better within the
tissue.
Special considerations for supermicrosurgery
Supermicrosurgery was coined by Isao Koshima to describe
anastomosis of blood vessels smaller than 1 mm (0.3 to
0.8 mm).1 The technique has its application, mainly in
very distal replantation, lymphatico-venous anastomosis, and
perforator flaps.1,2 Special instruments are crucial for success.
These instruments include a surgical microscope with the
highest currently available magnifying power, with 50× mag-
nification, the thinnest titanium forceps, and the smallest
surgical needle (12-0 nylon).
The microscope has high-power (50×) magnification and
allows a 20-cm working distance, which was impossible with
microscopes of 20× magnification.2
Anastomotic devices
Despite the fact that microsutures are nowadays relatively
inexpensive, reliable, and readily available, they do not fully
meet the criteria of an “ideal” anastomosis. Many nonsuture
techniques have developed in the search for faster and less
traumatic anastomosis.
In 1962, Nakayama et al.49 introduced an anastomotic
device consisting of two metallic rings and interlocking pins
that remain in  situ as a permanent implant. The Unilink
system developed by Östrup and Berggren in 1986,50 the 3M
and ACE coupling devices that were adaptations of this
ring–pin device, is currently marketed under the name Micro-
vascular Anastomotic System. This system consists of two
disposable rings made of high-density polyethylene with a
series of six to eight evenly spaced 0.16-mm diameter stainless
steel pins that are implanted with a reusable anastomotic
instrument.

449
General principles of microvascular surgery
perform 100%-patent microanastomoses is the first step on the
road to becoming a competent microsurgeon.
The working environment
The prerequisites of good microsurgical work are a calm
disposition and patience. The surgeon must be able to concen-
trate on the procedure without unnecessary interruptions and
should not be hurried. It is inadvisable to work too long at a
stretch and it is perfectly justifiable to take a break during long
sessions under the microscope or when using surgical loupes.
Undoubtedly, the presence of a competent assistant and a
knowledgeable specialized scrub nurse makes a big difference
to the speed and ease of the operation. However, it is not
uncommon for microsurgeons to operate late at night, alone,
or on challenging vessels. Therefore, endurance and persever-
ance are virtues.
Training
“Some are born microsurgeons while others become so through
discipline and training.”
Because of the inherent complexity and the increased dexter-
ity and hand–eye coordination required, the traditional
apprenticeship model of surgical training cannot be as readily
applied to microsurgery; and a special microsurgery appren-
ticeship in the form of fellowship becomes a must.
Although trainees can learn the techniques from senior
surgeons in a clinical setting, training should ideally begin
in the laboratory,95,96 with novices starting by familiarizing
themselves with instrument handling under magnification,
progressing from suturing stretched surgical gloves97 or sili-
cone tubes98 and then to live anastomoses in a rat model.99–102
Then in the clinical setting, trainees are usually given the
opportunity to do the second vein first, and after achieving a
steady patency, the arterial anastomosis can be handed to
them under supervision. It is only when they can do both the
vein and the artery well under supervision over multiple
times that they can be left on their own. Challenging condi-
tions are left to the more experienced members of the team.
Planning and positioning
In surgery, time spent planning and positioning is never
wasted and this is especially true for microsurgery. In the
right position, movements will be easier and the procedure
will progress faster. It is important to be comfortable as
comfort often relates directly to success,37 while poor planning
and positioning result in fatigue, frustration, and even failure.
Choosing the right incisions and the right positioning of
the patient becomes easier with experience. A two-team
approach can reduce the operating time and proper patient
positioning alleviates the need to reposition the patient during
surgery.
The surgeon should position him- or herself comfortably.
If seated, preferably on a self-adjustable stool, legs should be
under the operating table with feet flat on the ground. This
provides a stable base that can be maintained for prolonged
periods of time. The forearms should rest on folded drapes
such that they are approximately at the same level as the
anastomosis. These small details will minimize tremor and
fatigue.
Two adhesives have been studied for use in anastomoses:
fibrin glues, and cyanoacrylate glues. To prevent the glue
entering the vessel lumen, it was essential first to approximate
the vessel walls with conventional sutures, thereby reducing
the total number of sutures required for an adequate seal.
Fibrin glue is now commercially available as two compo-
nents, one with fibrinogen, factor XIII, and plasma proteins
and a second with thrombin, aprotinin, and calcium chlo-
ride. When mixed together, it imitates the final pathway in
coagulation. Fibrin glue has been used to seal anastomoses,
both experimentally68 and clinically.69,70 In a comparative
study of fibrin glue in free flaps,71 the application of fibrin
glue reduced the number of sutures required to complete
the anastomosis and significantly reduced the anastomotic,
but not ischemic, times with a slightly lower survival rate in
the suture-only group. Although these demonstrate a faster
union without compromising patency rate,70,71 fibrin has
not achieved clinical popularity, partly because of concerns
that glue might inadvertently enter the vessel lumen, and
the potential for allergic reactions and anaphylaxis.72–74 Cya-
noacrylates have been used experimentally, but have been
plagued by findings of histotoxicity,75 marked foreign-body
granulomatous response, extreme thinning of the vessel
wall, splitting of the elastic lamina, and calcification of the
media.76,77 2-Octyl-cyanoacrylate, however, might be less
toxic.78,79
Welding with thermal80,81 or laser82 energy has long been
advocated but, despite intensive experimental investigation,
its clinical application remains scarce. There are no clinical
reports of thermal welding to date. Different laser types
(neodymium : yttrium-aluminum-garnet,82 carbon dioxide,83,84
argon and, most recently, diode lasers85,86) have been used,
showing up to 100% patency rates and better blood flow in
veins when compared to conventional suturing techniques.
Laser-activated protein solders have been introduced to
achieve more strength.87 In an experimental setting, a diode
laser-assisted carotid artery end-to-end microanastomosis
provided an equal survival rate as a contralateral suture
anastomosis, with a shorter anastomosis time, and scanning
electron microscopy showed faster healing on the laser
side.86,88 Although later studies have shown promising results
on tensile strength, the fear of possible weakening at the site
of the anastomosis with consequent pseudoaneurysm forma-
tion has so far prevented the clinical use of laser welding. In
a study of 27 patients with laser-assisted microvascular anas-
tomosis, there was a 96.6% overall success rate with one
rupture of the arterial anastomosis and three hematomas
requiring surgical evacuation.89
Other experimentally studied methods of anastomosis
have included cylindrical or T-shaped intravascular stents.90,91
An external metallic ring has been suggested to keep the
cylindrical form of a sutured anastomosis and to avoid
through-stitching.92–94
General principles of
microvascular surgery
Success in microvascular surgery is multifactorial. Of the
many factors attributed with success, technical skills in vessel
anastomosis are a must-have craft, and learning how to

450
CHAPTER 24 • Principles and techniques of microvascular surgery
Once the recipient vessel has been adequately exposed and
identified, dissection of the vascular pedicle proceeds under
loupe magnification to free sufficient length to allow a tension-
free anastomosis. The total length of dissection ultimately
depends upon the length of the chosen flap’s pedicle, depth
at which the recipient vessels are situated, the size of the
vessels, and the technique of anastomosis to be used. Vein
grafts have been shown to reduce success rates and can
usually be avoided if proper preoperative planning has been
made. If the recipient vessels are deep, for example the inter-
nal thoracic vessels in breast reconstruction, a greater length
of vessel needs to be dissected in order to orientate them in a
more desirable position or even more superficially to allow an
unobstructed view that will facilitate the anastomosis (Fig.
24.1). Gross trimming of the adventitia is performed around
the area of the anastomosis, allowing sufficient length of
trimmed vessel for application of the vascular clamp. The
Next the microscope should be positioned so that it does
not obstruct movement, while providing maximum control
and maneuverability. However, the location of the anastomo-
sis often dictates where the microscope is ultimately placed.
The microscope base is then fixed to allow the surgeon suffi-
cient room to maneuver the microscope into the exact
position.
Securing the flap or flap inset
The inset of the flap should be considered before the anasto-
mosis is performed. After circulation is restored, the flap
swells and bleeds from the edges and this can make insetting
the flap in deep recesses particularly difficult. This is espe-
cially true in head and neck surgery where the flap may be
required in tight, hard-to-reach areas with limited visibility.
The inset should be performed first, ensuring that good
hemostasis has been achieved before the pedicle is divided
after flap harvest. Partial or complete inset of the flap before
the anastomosis also allows for a more accurate judgment of
pedicle length, avoiding problems resulting from tension or
redundancy. Tailoring or thinning the flap, however, is better
performed while the flap is perfused either before pedicle
division or after the microanastomoses to allow better control
of bleeders and avoid hematoma. In some cases, such as in
breast surgery, where the anastomosis lies deep to the inset,
there is no choice but to inset the flap after the anastomosis is
completed. In such instances, the flap is just secured near the
defect, allowing adequate exposure and positioning of the
vessels.
Selection and dissection of recipient vessels
Another important factor in ensuring success of free-flap
surgery is the use of healthy recipient vessels of appropriate
size with good outflow. Ideally they should be away from
zones of trauma and sites of irradiation. A healthy vessel has
a soft wall and a vascular sheath that can be easily dissected,
while traumatized vessels may be encased in fibrotic tissue
which is prone to bleeding during dissection. It is sometimes
necessary to assess the presence and quality of the recipient
vessels, particularly following irradiation and stiff neck phe-
nomenon, lower extremity trauma or in patients with long-
standing diabetes or atherosclerotic disease before flap
harvest. Preoperative angiography is indicated whenever in
doubt regarding the availability or quality of recipient vessels;
for instance, if one or both pedal pulses are not palpable
or audible by Doppler in the setting of previous trauma.
However, it might not add relevant information if at least one
pedal pulse is palpable,103 and normal findings may not
always translate into healthy usable vessels.
For free flaps to the extremity, clinical suspicion of vessel
damage, ankle/brachial pressure index, systolic toe pressure,
and hand-held Doppler auscultation may determine the need
for formal angiography. Other considerations in deciding
which recipient vessels to use include a single-vessel leg,
multiple previous free flaps, and the availability and adequacy
of recipient veins.
In head and neck reconstruction, multiple free flap
reconstruction, irradiation along with frozen neck, severe
atherosclerosis with peripheral artery disease, complicated
osteoradionecrosis may all justify further angiographic
studies.
Fig. 24.1  Horizontal vessel orientation allows both lumens of the vessel to be
adequately visualized.

451
General principles of microvascular surgery
Any debris is gently irrigated away (Fig. 24.3) or atraumati-
cally removed with microforceps. Failing this, the vessel
should be cut back, without compromising the flap pedicle
length, to attain a healthier vessel segment. Occasionally, a
suboptimal vessel intima has to be accepted and a successful
outcome is then dependent on meticulous anastomotic tech-
nique. Some surgeons will choose to cut the vessel back to a
healthy level at the expense of length, opting to use an inter-
positional vein graft in such situations since inadequate
debridement of vessels is often a major cause of flap failure.
The vessel wall consists of three principal layers. The
innermost tunica intima is formed by a single layer of endo-
thelium resting on a basal lamina. External to this is a thin
subendothelial layer consisting of connective tissue adjacent
to the internal elastic lamina that separates the tunica intima
from the tunica media. The tunica media consists mainly of
smooth-muscle cells and is the thickest layer of the arterial
wall. In veins, however, this layer is much thinner and,
sometimes in lesser veins, almost indistinguishable. The
tunica media is covered by the external elastic membrane,
and the outermost layer of the vessel wall is the tunica
quality of the artery and vein must then be checked. Under
microscope magnification, the vessels are inspected for
signs of damage that indicate the need for more proximal
dissection.
It is vital to check the flow within the artery. Expansile
pulsation of the vessel usually indicates adequacy but should
be confirmed by healthy spurting from the divided vessel. If
a healthy-looking vessel does not spurt well, check that the
patient is normotensive. Steps to relieve vasospasm should be
taken and are discussed later in this chapter. If there is still no
relief, the vessel should be cut back until healthy spurting is
encountered. Once this is confirmed, a vascular clip can be
applied while waiting for the flap to be harvested or to be
inset.
The ideal recipient vein should be at least as wide as the
flap vein. If the recipient vein is smaller in diameter, it may
produce a bottle-neck effect and compromise drainage of
the flap. The vein is divided to assess its quality and good
backflow from the vein indicates a fairly health vessel. If there
is any doubt, a small catheter may be introduced into the
lumen and heparinized saline flushed into the vein. If there
is little or no resistance, the vein is likely to drain well. If high
pressure is required to flush the vein, tying off tributaries
near the site of anastomosis may help reduce the backflow.
A single or double clamp is then applied in preparation for
anastomosis.
The vessels should be irrigated during and after dissection
with heparinized saline and, on completion of the dissection,
it is common practice to cover the vessels with 2–4% lidocaine
or 3% papaverine-soaked gauze pieces to prevent desiccation
and vasospasm.
When the flap is ready for revascularization, the vessel
ends to be anastomosed are placed in a double approximating
clamp under microscope magnification. An appropriate-sized
clamp is chosen to allow an adequate length from both vessels
between the two clamps. This allows the vessels to be
manipulated so that the lumen and intima of both can be
clearly visualized whilst allowing the needle to be easily
maneuvered. Moist gauze placed beneath the vessel setup is
a useful way to elevate the plane of anastomosis and orientate
the vessels into a horizontal lie to aid the anastomosis. It also
serves as a wick to mop up any pooling fluids that may hinder
the anastomosis. And, a silastic tube attached to a suction
system and introduced to the microanastomosis site covered
with moist gauze can further facilitate drainage without the
risk of sucking the anastomosed vessels. Pliable nonadherent
and nonreflective background material is placed under the
vessels and clamps. If the clamps will not lie flat, a moist
gauze piece is usually sufficient to weigh them down and
keep them in position. Four moistened gauze pieces are
placed around the vessel and clamp to prevent the suture
from adhering to surrounding structures. Good hemostasis
should be maintained at all times. Even a small but constant
trickle of blood will obstruct the working field, decrease flap
perfusion,104 and potentially results in spasm and causes
thrombus formation and anastomotic failure.
Preparation of vessels
The lumens of the vessels must be inspected for irregularities
such as intimal tears or separation from the media, thrombi,
atherosclerotic plaques, and friable calcified walls (Fig. 24.2).
Fig. 24.2  Loose intima.
Friable walls
Separation of
intimal walls
Separation of
medial walls
Intraluminal valves,
clots, flaps, tears
Branches
near anastomosis
Fig. 24.3  Intraluminal irrigation of vessels.

452
CHAPTER 24 • Principles and techniques of microvascular surgery
adventitia. This comprises loose areolar connective tissue
that contains the vasa vasorum, which nourishes the vessel
wall.105 Veins consist of the same layers as arteries, but the
layers are less defined, particularly with regard to the tunica
media which in some lesser veins is almost indistinguishable
(Fig. 24.4).
Loose adventitia can be peeled off the vessel wall using
microforceps or sharply trimmed by pulling it towards the
lumen and cutting parallel to the luminal edge (Fig. 24.5) to
a distance of 3–4 mm from the anastomotic site. It has been
shown that neither method completely removes all the adven-
titia and that sharp dissection appears to cause less damage
to the vessel.106,107 The main purpose is to improve visualiza-
tion of the vessel ends and prevent the adventitia from falling
into the lumen while tying the knot. Alternatively, a more
radical trimming is performed by cutting the tented adventitia
parallel to the length of the vessel, meticulously avoiding
injuring the tunica media (Fig. 24.6). Avoid overly aggressive
adventitial stripping as this may cause necrosis of the vessel
wall at the anastomotic site with resultant false aneurysms. In
Fig. 24.4  Cross-sectional view of artery (left) and vein
(right).
Artery
Vein
Subendothelial layer
Internal elastic lamina
Tunica intima
Endothelium
Tunica media
Tunica adventitia
Fig. 24.5  Sharp trimming of adventitia.
Fig. 24.6  More radical resection of adventitia.
Fig. 24.7  Gentle luminal dilatation of the vessel end.
smaller veins with thin tunica media, it is advisable to remove
only the adventitia that overhangs the vessel ends.
The vessel lumens are gently dilated in two different planes
with a vessel dilator or microneedle holder and the stretch
maintained for a second (Fig. 24.7). This will aid the suturing
process, prevent vasospasm, and allow intraluminal blood to

453
Microvascular anastomosis techniques
Fig. 24.9  Interrupted suturing techniques by placement of three stay sutures at
120° or at 180° to ease subsequent placement of sutures.
Anastomotic sequence
There is no consensus regarding optimal anastomotic
sequence. In reality, the relative vessel position will dictate
whether the artery or vein is first anastomosed, with the
deeper, more-difficult-to-reach vessel being repaired first.
If the anatomy does not restrict the choice, arterial repair
first may be a sensible choice as it will shorten the warm
ischemia time. The re-establishment of circulation may also
reveal the more dominant venous drainage to aid the selection
of which donor vein to use and more importantly to detect
any possible twist, kink, or compression in the pedicle, in
particular the perforator. There are disadvantages, however,
as the flap may start bleeding and affect the anastomosis of
the vein. Subsequent venous congestion may increase bleed-
ing from the flap edges and allow a buildup of free radicals.
To avoid this, the second vein may be intermittently released
to allow drainage of the flap. Alternatively, the venous anas-
tomosis could be performed first, which additionally allows
for better adjustment of the pedicle length, although this will
delay revascularization of the flap.
An early experimental study showed that flap failure in
straightforward cases was highest if the arterial anastomosis
was performed first and immediately unclamped. This was
attributed to venous congestion.108 However, other studies
have failed to show an optimal sequence of anastomosis in
both skin and muscle flaps.109,110 In our practice of more than
1000 free flaps per year, we routinely repair the artery first
and leave it unclamped as the vein is being repaired and have
not noticed major problems related to the temporary venous
congestion. If there is a second comitant vein, however, we
avoid venous congestion by allowing the less dominant vein
to drain freely into gauze away from the operating field.
Some surgeons advocate two venous anastomoses where
possible to avoid complications of venous insufficiency, and
Khouri et al. reported a significantly higher failure rate when
only one venous anastomosis was performed (4.3% versus 0%
if two anastomoses).111 A single venous anastomosis to a suit-
able recipient vein however will provide adequate drainage
and reduce operative time without increasing morbidity.
Futran and Stack showed equivalency of single and dual
venous anastomosis with respect to flap survival in a series
of 43 free radial forearm flaps.112 This too is our clinical experi-
ence. Sound judgment is required and, if the first vein is less
reliable or if its patency is uncertain, a second venous anasto-
mosis should be performed to secure venous drainage of the
flap.
Microvascular anastomosis techniques
Having discussed the general principles of setup, vessel
preparation, and common pitfalls, this section now focuses on
how these principles can be applied to the different anasto-
motic techniques to achieve success.
Suturing techniques
End-to-end anastomosis
The method of performing the anastomosis depends largely
on personal preference. The end-to-end anastomosis using
be flushed out with heparinized saline, and overcome minor
degrees of size discrepancy. Blood beyond the clamps, in
undamaged vessels, is not in contact with wound thrombo-
plastins and is not at risk of clotting. A hemostat artery forceps
is used to bring the two clamps towards each other so that
the vessel ends are just touching or with minimal overlap
(Fig. 24.8).
Fig. 24.8  Using artery forceps to bring the clamps together.

454
CHAPTER 24 • Principles and techniques of microvascular surgery
and allow platelet aggregation and thrombus formation.114
Additionally, sutures that are too tight can damage the media
of the arterial wall and if at least a third of the vessel wall
undergoes necrosis, re-endothelialization does not occur and
occlusion of the lumen invariably follows.115,116 Tight sutures
may also narrow the anastomosis site resulting in thrombus
formation.
Sutures are then placed in between the stay sutures, aiming
to place the smallest number of sutures to achieve a leakproof
anastomosis, and the approximator clamp is turned over. The
back wall can now be sutured by either placing a suture
exactly midway between the two existing stay sutures or, with
experience, sutures can be accurately placed to complete the
anastomosis. As the anastomosis progresses, it becomes
increasingly difficult to visualize the lumen and it is advisable
to leave the last few stitches untied, leaving the ends loose
until the last suture is placed. These sutures are then tied in
turn. It is better to leave any apparent gaps alone until the
clamp is released and the vessel refills in order to prevent
through stitching. If the vessel configuration does not allow
the clamp to be turned over, the back wall-up technique must
be employed. The first suture is placed posterocentrally and
subsequent sutures are placed on either side of the first knot,
working around the circumference and spacing them appro-
priately apart. Once the back wall is completed, the anterior
wall can be sutured using the interrupted, continuous, or
open-loop suture techniques (Figs. 24.11 & 24.12).
Continuous suturing is a technique suitable for minimally
size-discrepant vessels larger than 2 or 3 mm and not only can
significantly reduce anastomosis time by nearly half but is
more hemostatic117 (Fig. 24.13A). However, there are problems
with suture entanglement; the sutures must be placed meticu-
lously and the final tying of the knot must be accurate to
prevent purse-string constriction of the lumen. It is advisable
to place two or three stay sutures, leaving one suture end long.
Starting from the last stay suture, running sutures are placed
at regular intervals and tied to the next stay suture. Then the
needle is passed under the vessel and the double clamp
turned over and suturing continued. This reduces the likeli-
hood of creating a purse-string effect (Fig. 24.13B). With
meticulous attention to detail, patency rates of 97.5–100% can
be achieved118–120 in both veins and arteries and end-to-end
and end-to-side repairs.
Open-loop suturing is a technique that combines the
convenience of the continuous running suture with the
Fig. 24.10  Knot tying with a double throw.
Fig. 24.11  (A, B) Placing a halving suture may facilitate accurate stitch placement when performing end-to-end anastomosis with interrupted suturing.
A
B
interrupted sutures is by far the most common method used.
It is simple and appropriate for most arterial and venous
anastomoses. A halving, triangulation, or “back wall-up”
technique can be used to perform this anastomosis (Fig. 24.9).
Carrel recommended avoiding luminal narrowing at the
anastomotic site, avoiding the creation of folds and a rough
inner surface of the vessel, and opposing the two intimal
edges closely. These principles still hold true today. In his
original description,113 three stay sutures were placed at 120°
from each other. Cobbett modified this, using only two stay
sutures at 120° from each other, and found that, when ten-
sioned apart, the longer back wall fell away from the shorter
front wall and reduced the chance of taking a through stitch,
where the intima of the posterior wall is incorporated into the
suture. Another alternative to this is placing the two stay
sutures at a 180° angle to ensure even spacing between the
sutures.
The second stay suture is the most important, difficult one
and will determine the technique. The needle should penetrate
the vessel wall in perpendicular fashion incorporating all the
layers of the vessel, especially the intima. The size of the bite
is determined by the thickness of the wall and the suture, and
should be maintained throughout the anastomosis. The first
throw should be a double one to ensure that it maintains the
intended tension (Fig. 24.10), and then two single throws
follow to complete the knot. The knots are snugged down by
sight and not by feel and should stop when the two vessel
edges meet and slightly evert. If the sutures are too tight,
small tears in the vessel wall may expose the subendothelium

455
Microvascular anastomosis techniques
advantages of interrupted suturing technique. First a running
suture is performed leaving the loops small enough that they
do not flop to the side, or two separate stay stitches are placed
and running suture performed in between. The first suture is
tied and the suture ends cut short. The next loop is pulled
through and tied in a similar fashion and cut, the maneuver
repeated until all the loops have been tied (Fig. 24.14). This
technique reduces the number of maneuvers and the need to
handle the needle constantly after each suture. Maximal
lumen visualization is maintained throughout and the risk of
purse-stringing is eliminated. This method needs practice,
however, as the loops can easily become entangled and time
may be wasted untangling them.
Sleeve anastomosis, introduced by Lauritzen121 in 1978, is
a variant of the end-to-end technique, “end-in-end”, and
entails telescoping the vessels by using two extraluminal
sutures that pull one vessel inside the other (Fig. 24.15). Fewer
sutures are required, resulting in reduced anastomosis time
and less vessel trauma, but low patency rates reported by
Sully et al.122 prevented this technique from gaining popular-
ity, despite contradictory results by others. The sleeve tech-
nique was suggested to be limited to vessels with size
discrepancy. A modification of “hemi-invagination” by Riggio
et al.123 improved patency rates to 95–100% by placing a side
cut on the overlapping vessel and adding a stitch at its apex,
thus effectively dilating the vessel to facilitate anastomosis of
vessels of equal size. However, it was only tested on rats;
clinical studies are lacking.
End-to-side
The end-to-side anastomosis is particularly useful when there
is significant vessel size or wall thickness discrepancy124 or when
Fig. 24.12  Back wall first.
A
Fig. 24.13  Continuous suture. (A) Complete anastomosis using one continuous suture.
Continued

456
CHAPTER 24 • Principles and techniques of microvascular surgery
B
Fig. 24.13, cont’d (B) Using stay sutures placed at 180° and performing continuous sutures between the two and tying off to each stay suture prevents purse-stringing of
the lumen. (From Chen YX, Chen LE, Seaber AV, Urbaniak JR. Comparison of continuous and interrupted suture techniques in microvascular anastomosis. J Hand Surg Am.
2001;26:530–539.)
there is a need to preserve the distal circulation, as in a single-
vessel leg. Anecdotally, end-to-side anastomosis, especially, in
lower extremity could be less prone to vessel spasm, associated
with higher success rates,125 but not necessarily of higher patency
rates compared with end-to-end anastomosis.126
In order to perform an end-to-side anastomosis, an arteri-
otomy or venotomy has to be made in the recipient vessel.
This may be triangular or elliptical or a simple longitudinal
slit that will open up due to contraction of the muscle in the
vessel wall. The hole should not have irregular edges as this

457
Microvascular anastomosis techniques
If the flap vessel is long enough, the anastomosis can be
performed with stay stitches at the distal and proximal ends
of the arteriotomy and the “front” wall can be completed
before pulling the vessel towards you and performing the
“back” wall as described by Godina.125 If there is insufficient
length to manipulate the donor vessel, then the wall further
from you must be performed first (Fig. 24.17). The sutures are
then placed radially to the center of the arteriotomy. Persistent
leakage from the distal and proximal ends may be severe if
the sutures are placed transversely.
According to Godina, the additional advantages of this
anastomosis included a higher success rate, greater freedom
of operative planning, and technical simplicity in terms of
access to the vessels and it was his anastomotic technique of
choice.125 However, in a study of over 2000 microvascular
anastomoses in more than 900 tissue transplants, end-to-end
and end-to-side microvascular techniques were found to be
equally effective when properly applied. Patency approached
100%.126 Although arterial anastomosis patency was similar to
end-to-end anastomosis, end-to-to side venous anastomosis
had a higher success rate in a study of 90 rats.127 In a further
experimental study, while there were no differences in vessel
patency between an end-to-side hole and an end-to-side slit
technique, the latter was easier to perform in vessels less than
1.5 mm in diameter.128
Use of the coupler
The use of the anastomotic coupling device is the most
common alternative to the conventional suture. It is a time-
saving alternative that consistently produces equivalent
patency rates to conventional methods. The outer diameter of
each vessel is measured after gentle dilatation against the
may weaken the wall and facilitate thrombus formation. A
sufficient length of recipient vessel is dissected to allow place-
ment of two clamps on either side of the anastomotic site and
the adventitia trimmed nearly circumferentially between the
two clamps. A baby Satinsky clamp is useful for clamping the
recipient vessel to facilitate the anastomosis while maintain-
ing the flow and is less traumatic than bulldog clamps.
Alternatively, vascular slings may be double-looped around
both ends and tightened to act as stabilizers and to cut off the
blood flow to the segment of vessel. A single stitch is taken
transversely at the anastomotic site and used as a stay suture.
Holding this suture up, the vessel around the suture is excised
using microvascular scissors and extended as necessary with
a no. 11 blade (Fig. 24.16). Alternatively, the Acland–Banis
arteriotomy clamp can be used to pick up and hold part of
the vessel wall that is to be excised. The blade is then held
close against the clamp tip, allowing an ellipse to be excised.
Ideally this opening should not be longer than the diameter
of the donor vessel as it will stretch once the clamps are
released.
Fig. 24.14  Open-loop suture.
Fig. 24.15  Sleeve anastomosis.
Fig. 24.16  End-to-side anastomosis. Making the arteriotomy.
Fig. 24.17  End-to-side anastomosis. In cases where there is insufficient length to
rotate the vessel, the back wall needs to be sutured first.

458
CHAPTER 24 • Principles and techniques of microvascular surgery
vessel-measuring gauge. In size-discrepant vessels, a coupler
is chosen such that the internal diameter of the device is the
same as the measured outer diameter of the smaller vessel.
The coupling device is loaded on to the anastomotic instru-
ment, ensuring that it is well seated. The anastomotic instru-
ment is placed perpendicular to the vessels, and the vessel
end threaded through the ring. The edges of the vessel are
impaled securely on to the first pin, taking a bite that is
approximately 1–2 pin diameters with an adequate intimal
bite. The vessel is impaled on every other pin first before
completing the intermediate pin placements to ensure it is
evenly spaced. Draping the flap vessel first allows easier posi-
tion of the coupler than the less mobile recipient vessel. The
rings are then brought together by turning the applicator
handle clockwise and reinforced using hemostat artery
forceps. The applicator handle is turned counterclockwise to
eject the device (Fig. 24.18).
Difficult, less commonly encountered
microvascular anastomosis
Anastomosis between size-discrepant vessels
Despite careful planning, size-discrepant vessels are com-
monly encountered. More problems are encountered if the
inflow from the recipient is big while the flap artery is small, or
if the outflow of the flap is big while the recipient vein is small,
compared with the opposite conditions. It is better remembered
that sudden change of caliber may still cause turbulence that
predisposes to thrombosis. Various techniques are used to deal
with this, and vessel mismatches of up to 4 : 1 can be anasto-
mosed end-to-end depending on the level of technical skills.
The simplest method is gently to stretch the smaller vessel
mechanically to match the larger one, placing interrupted
sutures further apart on the larger vessel. Alternatively, placing
a fish-mouth incision or obliquely cutting the smaller vessel
Fig. 24.18  Application of the coupler device. (A) The vessel is oriented at 90° to the applicator and the vessel end impaled evenly on the pins. (B) The vessel is
anastomosed and released by turning the applicator handle.
A
B
can reduce the discrepancy. Angles of more than 30° of the
oblique cut may cause kinking, and should be avoided.
Another technique involves performing the anastomosis
just distal to a side branch and opening up the distal wall so
that the V shape of the branch is now the vessel end. When
the discrepancy is greater than 3 : 1, consider an end-to-side
anastomosis, a vein graft to graduate the discrepancy, or using
a side branch of the larger vessel, which may be a better size
match. As a last resort, the smaller vessel is dilated maximally
and sutured as widely as possible to the larger vessel. The
remaining vessel can be directly sutured to itself and an
obliquely placed surgical clip will taper the vessel and mini-
mize turbulence (Fig. 24.19).
A discrepancy between the vessel walls may also be
encountered but does not usually pose a problem. Gentle
dilation will serve to thin the wall but if a significant discrep-
ancy persists, the key is to take equal bites of the intima from
both vessels, incorporating less of the media and adventitia
of the thicker-walled vessel.
Vertically oriented anastomosis
This is the most challenging configuration of vessels. If pos-
sible, change the position of the body part, and adjust your
position or table to make the anastomosis more horizontally
oriented. Freeing up more of the vessel length will allow the
vessel to be manipulated into a more horizontal plane using
properly placed gauze pieces. If the position cannot be
changed and there is limited space to rotate the vessel, reduce
the magnification of the field as this will increase the depth of
field, reducing the need to alter the focus of the microscope
constantly on each vessel end.
Atherosclerosis and loose intima
Atherosclerotic vessels are commonly encountered given that
free-flap surgery is extended to the elderly and those with

459
Microvascular anastomosis techniques
Fig. 24.19  Size-discrepant vessels. (A) The smaller vessel end can be dilated and stretched to match the larger one, cut obliquely to increase the diameter or a
longitudinal side cut of the smaller vessel can be made. (B) The smaller vessel can be sutured as widely to as much of the larger vessel. A clip can be brought across
obliquely to taper the remaining end of the larger vessel and may help to reduce turbulence.
A
B
Not more than 30°
30°
cardiovascular disease. However, radiotherapy is also respon-
sible for irradiation-induced atherosclerosis,129 further increas-
ing the exposure to atherosclerotic vessels in microsurgical
reconstruction.
If a significant plaque is found, cutting back the vessel to
healthier intima or even choosing another vessel altogether
may be necessary. The artery should be divided with sharp
scissors in one cut to minimize separation of the atheroscle-
rotic intima. Sometimes atherosclerotic plaques can create a
false lumen, or may appear as another vessel wall, and irregu-
larities in these plaques can turn inside the lumen as an
intraluminal flap, which may cause thrombosis. Therefore,
after cutting the artery, the atherosclerotic plaque should be
carefully looked for, and the cut edge should be trimmed
using fine scissors. This trimming should be performed slowly
and circumferentially, in a manner resembling opening a can
rather than a guillotine cut.130
The vascular clamp should not exert too much tension as
this can fracture the calcified walls or plaques. So, proper
micro-clamp tension should be provided only in areas which
are not affected by atherorsclerosis, if used at all. One may
consider microclamps which are used for venous anastomosis
for both the artery and vein, so that less pressure is applied
when clamping.
A round needle is useful and meticulous placement of
interrupted sutures using the smallest microsuture should be
ensured. The intima must be visualized at all times and the
suture should ideally be passed from the inside of the lumen
of the atherosclerotic vessel to the outside to avoid further
separation of the intima from the vessel wall. This is possible

460
CHAPTER 24 • Principles and techniques of microvascular surgery
if only one vessel is diseased. But when both recipient and
donor are diseased, a double-needle suture may be useful. If
unavailable, then careful counterpressure from forceps placed
within the vessel as the needle is passed will minimize intimal
separation (Fig. 24.20). Vessel dilation should be avoided and
careful vessel wall eversion avoids leaving raw areas exposed
to the blood flow. Too much tension, however, may erode the
plaque and tear the vessel wall.
End-to-end is preferred over end-to-side that usually
causes more direct exposure of the atherosclerotic plaque and
its edges, resulting in increased risk of thrombus formation.
If end-to-side is unavoidable, as in single vessel-leg, an
end-to-end anastomosis is used after providing a T or Y vein
graft. However, vein grafts are more prone to thrombosis in
these settings and the anastomosis should be finished as soon
as possible because prolonged duration may increase the risk
of thrombosis, causing long-term blood stasis and exposure
with mechanical micro-traumas.130
Microvascular grafts
An increased storehouse of flaps with various pedicle lengths,
technical refinements, and proper planning has been key to
diminishing the need for vein grafts.22,131 Despite this, they are
still sometimes necessary, particularly in the trauma setting,
vessel depleted neck, and re-explorations. There is an associa-
tion between interposition vein grafting and free-flap compli-
cation and failure;111,132,133 however this may be a reflection of
the complexity of the case and other factors such as vessel
quality134 and hematoma formation135 that can independently
lead to flap failure rather than the actual use of the vein grafts.
Indeed, other studies have shown that patency and flap sur-
vival are not reduced by the use of vein grafts,136,137 which can
be performed quickly and safely if certain principles are
followed.
Fig. 24.20  Use of forceps to provide counterpressure to minimize trauma and
separation of the intima.
The indications for vein grafts include a recipient vessel out
of the reach of the pedicle or under tension despite adjust-
ments in flap inset or skeletal shortening, considerable size
mismatch, and the need to place the anastomosis outside the
zone of injury/radiation. Occasionally the judicious use of a
Y-shaped vein graft will serve a further function of being able
to restore circulation to the distal stump.138
The harvest of the graft is just as important as the subse-
quent anastomosis and should be done with loupe magnifica-
tion. Ideally, the vein graft should match the caliber of the
vessels to be anastomosed.139 If possible, upper limb defects
are bridged with upper limb veins. The workhorse vein graft
is the great/lesser saphenous vein with the advantages of
length and two-team approach. Other alternatives include the
cephalic and the comitant veins of the free flap. Volar forearm
and dorsal foot veins are preferred in finger and hand replan-
tation for size-match and arch-like configuration. All vein
grafts need dilatation prior to anastomosis to allow a better
wall thickness match. If there is a concurrent lack of soft-tissue
cover, a narrow venous flap for arterial gaps may solve both
problems at once.140 The vein should be handled minimally
during the dissection and all tributaries ligated or coagulated.
The length required should be marked out, remembering that
vein grafts contract after division only to lengthen consider-
ably, with the potential risk of kinking, after restoration of
high-pressure flow.
Since even short segments of veins may contain valves, the
direction of the vein is crucial and must always have ante-
grade flow. In our practice, the proximal end is marked with
a surgical clip. This facilitates hydrodilation of the vessel
which stretches the graft out to length, untwists the vein,
relieves vasospasm, and allows visualization of potential
bleeding points. The open end is then anastomosed first and
the clamp released for a final check that the direction is correct
and the length not redundant.
Arterial grafts have significant advantages over vein grafts,
such as the absence of valves, an anatomical taper, similar
luminal and wall-thickness profiles, and better handling
characteristics. Arterial grafts maintain their endothelium and
have less subintimal hyperplasia. They also produce more
prostacyclin relative to vein grafts in the first 3 weeks, result-
ing in greater antithrombogenic activity.141 However they
have not been shown to have significant advantages in the
context of microvascular surgery.142 They may be harvested
from the subscapular tree,143 anterior and posterior interosse-
ous arteries,144 radial or ulnar arteries, the deep or superficial
inferior epigastric artery,145 and the dorsalis pedis artery.
Testing patency
Patency should be assessed after the completion of each
anastomosis and the flap assessed for adequate perfusion
periodically through the operation. This can be done by
simple observation or by conducting a patency test.
The characteristics of the arterial pulsation are important
and can be expansile or longitudinal. The latter occurs in the
long axis of the vessel and is a sign of partial or complete
thrombosis. The flap will show no evidence of return of cir-
culation and the anastomosis should be redone. Other signs
of patency of the artery include good flow from the vein. If
the recipient vein fills well and has a natural round diameter
it is likely to be patent. If it is engorged and the blood column

461
General aspects of free-flap surgery
to treatment regardless of complexity, as technical concerns
become reduced. But since more complex wounds are created
through more radical surgery, for either tumor extirpation or
trauma debridement for which a suboptimal reconstruction is
the corollary of classic methods, the best outcomes often
cannot be achieved without utilizing microsurgery; this
further brings on, in many occasions, single-stage total recon-
struction and reverses, as a result, the reconstructive ladder/
lift.
Now, it is appropriate to say that with microsurgery, the
sky is the limit for reconstructive surgeons; this summarizes
what we have achieved thus far and what we are going to
witness years from now.
Advantages and disadvantages
The advantages of free microvascular tissue transfers over
more conventional methods of reconstruction have been well
documented. Free-flap surgery offers freedom of choice of
donor tissue components to achieve superior functional and
aesthetic results by replacing “like with like”, especially when
local or regional tissue is inadequate. The flap can be tailored
to meet specific requirements of the recipient site in size, form,
tissue components, and even function. In contrast to regional
or distant pedicled flaps that may require a multistage recon-
struction, the use of free flaps is often a single-stage procedure
that allows earlier mobilization and return to work, reduced
hospitalization and overall costs. The new tissue has better
cutaneous blood flow146 and vascularity that may enhance
wound healing and reduce infection. With an increasing
repertoire of flaps and refinements in their harvest, a donor
site which can be primarily closed with minimal donor mor-
bidity is favored and can often be used.
is darker than that in the recipient vessel, it is thrombosed and
will require reanastomosis. Other signs of a nonpatent venous
anastomosis will include engorgement of secondary veins
within the flap, and continuous dark bleeding from the edges
of the flap.
If in doubt, two simple tests can be performed distal to the
anastomosis. The first is an “uplift” test by gently hooking up
a thin-walled vessel until the column of blood is almost
occluded. If the vessel is patent, alternate filling and collaps-
ing with each pulse will be evident. The second is the empty-
and-refill test37 (Fig. 24.21). This test is slightly more traumatic
and should only be performed when needed, preferably on
veins not arteries, to minimize spasm or intima separation.
Gently occlude the vessel distal to the anastomosis, and, with
a second pair of forceps, empty a segment of the vessel by
occluding the vessel next to the first pair and running it in the
direction of the flow. The first pair of forceps is released and
the emptied segment refills immediately. If the refill is slug-
gish or absent, the vessel is not patent.
General aspects of free-flap surgery
Although the first clinical application of microvascular surgery
was in replantation, this soon evolved into free-flap surgery,
bringing about a new era in reconstructive surgery and allow-
ing the reconstruction of previously unreconstructable defects.
The concept of the reconstructive ladder and then the recon-
structive elevator were introduced as a series of reconstructive
options with increasing complexity; this approach to wound
management has served us well for the past three decades but
not anymore. With the advent of microsurgery, the aim shifts
Fig. 24.21  Empty-and-refill test. (A) Direction of flow across the anastomosis. (B) Two atraumatic forceps are placed downstream of the anastomosis. (C) The forceps
furthest away from the anastomosis is used to empty the vessel downstream. (D) The proximal forceps is released whilst the distal one continues to occlude the vessel. The
vessel should immediately refill confirming patency.
A
B
C
D

462
CHAPTER 24 • Principles and techniques of microvascular surgery
vascular thrombosis or flap failure as long as standard anti-
coagulant prophylaxis is maintained.162
Recipients and donor site evaluation
Irradiation impairs the quality of local tissues and vessels and
may predispose to complications at the recipient site.163,164
Khouri et al. found that reconstruction in an irradiated recipi-
ent site was a significant predictor of flap failure, with
increased odds of failure of 4.2,111 but many others have failed
to show that radiation significantly affects flap survival.163–165
In our experience of 145 patients with reconstruction in an
irradiated field, radiation and time between surgery and
radiotherapy had no bearing on overall flap survival but
increased the risk of reoperation and complications.166 Careful
dissection and meticulous attention to surgical technique
should be undertaken when performing the anastomoses.
Where possible, however, site the anastomosis outside the
area of irradiation.
Infected or traumatic wounds should be adequately
debrided and, if necessary, reconstructive surgery postponed
until adequate control of the wound is achieved. The zone of
injury needs to be taken into consideration and the anastomo-
sis placed outside this zone where possible. Preoperative
angiography or computed tomography angiogram is recom-
mended in patients with abnormal distal pulses,167 and in
those in whom both pedal pulses are not palpable/audible by
Doppler.103 Normal angiographic findings do not guarantee
the presence of vessels suitable for anastomosis, and routine
angiography is unjustified.168
Harvesting a free flap requires an intimate knowledge of
the anatomy of the vessels, and their variations, supplying the
transferred tissues. The design of the flap may be centered on
perforators that are mapped out by a hand-held Doppler
device169 or more accurately through color duplex ultra-
sound,170–172 computed tomography angiography with or
without three-dimensional reconstruction173–175 or magnetic
resonance imaging angiograms.176–178 Accurate preoperative
mapping has been shown to aid perforator selection, increase
the safety of perforator dissection, and reduce operative
time.172,175,178
Choice of flap
Preoperative planning and flap selection and design are more
important than the harvest itself. There is no flap ideal for all
circumstances and the surgeon must accept some compro-
mises to choose the most appropriate available flap for the
patient. Chosen well, the patient comes away with an optimal
result; chosen badly, and the entire reconstruction is set up to
fail.
The first question to answer is: “Does this defect need a free
flap?” If the answer is yes, then other factors to be considered
include the size and tissue components of the defect and the
goals of reconstruction. For example, for a young patient with
a benign tumor of the mandible, in whom functional outcome
is as important as aesthetic outcome, a flap that incorporates
vascularized bone for immediate or delayed osteointegration
of dental implants should be chosen (Fig. 24.22). Conversely,
an edentulous elderly patient with a poor-prognosis mandibu-
lar cancer and trismus may benefit from a more straightfor-
ward operation with a reconstruction plate and soft tissue flap
When both operation and recovery proceed as planned, the
advantages of free tissue transfer are clear. However, these
benefits have to be weighed against the risks of long surgery
and anesthesia spasm and microvascular thrombosis, re-
exploration, and the dreaded complication: flap failure.
Preoperative evaluation
Patient factors
Free tissue transfer is feasible and often successful in the pres-
ence of patient factors once considered to be high-risk for flap
failure. However, it is important to evaluate fully the fitness
of the patient for free-flap surgery to identify and reduce the
risk factors associated with poor outcome.
As with all major surgeries, cardiac and respiratory fitness
should be optimized before free tissue transfer. This encom-
passes good preoperative hypertensive and diabetic control.
Age, in itself, is not a contraindication to free-flap surgery as
long as the patient is in otherwise acceptable health and
deemed fit for anesthesia. The outcomes of free tissue transfer
in the extremes of ages are comparable to those in the general
population,111,147–152 although there is an increase in postopera-
tive medical complications in the elderly.
Smoking has not been shown to significantly affect vessel
patency, flap survival, and reoperation rates, but increases
donor site complications with poorer wound healing at the
flap–wound bed interface.153–156 However, patients should be
advised to stop smoking preoperatively as their risk of com-
plications approaches that of the nonsmoker if they stop
smoking 4 weeks before surgery.
Obesity clearly increases the risks of microvascular surgery
and is associated with increased hemorrhage and hemato-
mas.111 In 936 transverse rectus abdominis myocutaneous
(TRAM) flap breast reconstructions, the incidence of total flap
loss, hematomas, seromas, and overall donor site complica-
tions was higher in patients with a body mass index of over
30.
Alcohol withdrawal is also related to increased flap failure157
and nonflap-related complications158 and patients at high risk
for postoperative alcohol withdrawal syndrome should be
identified and treated prophylactically.
Diabetes mellitus is not an independent risk factor for
flap failure, but patients with diabetes mellitus have a 1.76
increased risk of perioperative complications.159
Liver cirrhosis is a risk factor for perioperative complica-
tions. Kao et al. showed that complications were high, but the
disease severity based on Child’s scoring system did not have
a statistically significant impact on those complications.
However, the risk of postoperative neck hematoma was sig-
nificantly higher in patients with more advanced liver
cirrhosis.160
Immunosuppression may pose a challenge to free flap
surgery. A review of 24 immunosuppressed patients found
out that prednisone correlates statistically with operative
morbidity, which implies that additional risks of delayed
wound healing, partial flap loss, and anastomotic thrombosis
should be expected in this group of patients.161 Patients with
collagen vascular diseases such as Raynaud phenomenon,
systemic lupus erythematosus, and scleroderma have
increased incidence for thrombotic events such as deep vein
thrombosis; however, they are not at increased risk of micro-

463
General aspects of free-flap surgery
over another in order to minimize the need for interpositional
vein grafts.
An important consideration is the potential donor site,
such as the cosmetic result of the donor site that requires skin
grafting and reduced muscle power and potential herniation
following muscle flap and even perforator flap harvest. Con-
sideration should also be given to the logistics of the flap
harvest, patient positioning, and the feasibility of using a
two-team approach to streamline the operation.
Timing
The timing of post-traumatic lower extremity reconstruction
has been the subject of ongoing debate since Godina first
recommended that they be performed within 72 hours of
injury.180 Today, when the free flap is actually performed is
largely determined by the surgeon’s experience and assess-
ment and the local healthcare system, logistics, and facilities.
The definitions of the ideal time periods also vary signifi-
cantly, with some defining acute reconstruction as the interval
ranging from emergency or immediate procedures within 24
hours to urgent procedures done within 72 hours, and others
suggesting that the first 24 hours be termed “primary free-
flap closure.”181 There are those who advocate reconstruction
within 72 hours182,183 or 5 days,184 but proponents of delaying
the reconstruction argue that the viability of an extremity
can be better assessed, the reconstructive procedure better
planned, and performed under better operating conditions.
In our practice, we have found that adequate debridement
results in a fresh surgical wound that can be reconstructed
at any time and that actual timing has little to do with the
final outcome of the flap. However, we agree that immediate
cover must be considered if vital structures are exposed and
that, on occasion, emergency free-flap transfer may salvage
a devascularized limb or a finger, in addition to improv-
ing the functional and aesthetic results and shortening the
hospital stay.185 In oncological reconstructions, immediate
reconstruction is performed at the same time as the abla-
tive surgery to achieve uncomplicated wound healing.
Reconstruction at the same time has been shown to delay the
delivery of adjuvant therapy modestly.186 In reconstruction of
the breast, if patients will receive or have already received
postmastectomy radiation therapy, the optimal approach is
delayed autologous tissue reconstruction after postmastec-
tomy radiation therapy. However, when postmastectomy
radiation therapy appears likely but may not be required,
delayed-immediate reconstruction, in which tissue expansion
is used, may be considered.187 A recent multicentric study
showed a surge in immediate reconstruction rate favoring
implant use due to an increase in the proportion of high-risk
patients undergoing immediate reconstruction. Interestingly,
though, autologous free tissue transfer also increased in the
high-risk group but not in the setting of premastectomy
radiotherapy.188
Microvascular anesthesia
The importance of stable anesthesia by an anesthetic team
familiar with microsurgery should not be underestimated.
Good pain, temperature, and sympathetic control should be
maintained throughout to prevent vasospasm and vasocon-
striction. Fine-tuning of blood pressure will help in ensuring
Fig. 24.22  Osteointegrated teeth in a fibula osteoseptocutaneous flap
reconstructed neo-mandible. (A) Segmental defect of the mandible after tumor
excision. (B) Double-barreled fibula inset. (C) Final appearance of the mandible
after osteointegrated teeth implantations.
A
B
C
with adequate tissue volume such as the anterolateral thigh
flap combined with vastus lateralis muscle that addresses the
primary goal of uncomplicated wound healing. This approach
reserves the potential for secondary optimal reconstruction in
cases not suitable for one-stage bony reconstruction.179 Appro-
priately sized recipient vessels must be available and must be
considered in deciding the length and caliber of the flap
pedicle. This may ultimately decide the suitability of one flap

464
CHAPTER 24 • Principles and techniques of microvascular surgery
minimizes donor site morbidity and allows the harvest of
only the specific components required for the reconstruction.
In areas where the anatomy of the cutaneous vessels has not
been studied extensively or with flaps with considerable
variation in anatomy of their blood supply, the detection of
an audible perforator with a hand-held Doppler probe may
form the basis of flap harvest.171 The vessel is identified at the
level of the fascia, through an exploratory incision, and if
sizeable (0.5 mm with good visible pulsation), then dissection
in a retrograde fashion will follow its course to the parent
vessel on which the flap may be raised as a free flap. This
concept has been termed “free-style free flaps”203 and these
flaps can be designed almost anywhere as long as small-
caliber vessels and small to medium-sized skin paddles are
acceptable when pedicle length is not critical.
To reduce donor site morbidity further, Koshima et al.
advocate supramicrosurgery,204–206 the dissection and anasto-
mosis of vessels with diameters of less than 1 mm. This allows
flaps based on vessels harvested without breaching the deep
fascia, facilitating a quick operative harvest time without
intramuscular dissection, but yields a very short pedicle that
requires highly honed surgical skills and extremely fine
instruments and sutures.
Combined flaps
When the flap consists of diverse tissue components with
multiple sources of vascularization, often discrete to each
component, the flap is called combined. Based on the physical
relationship between the flap components, the combined flap
is subdivided into conjoined and chimeric.207,208 In conjoined
flaps, previously known as Siamese, multiple anatomical ter-
ritories are dependent due to some common physical junction
yet each retains an independent vascular supply.208 In chimeric
flaps, on the other hand, there is no physical junction between
the territories, perforasomes, components, etc. The conjoined
flap has the advantage of providing large surface area while
the chimeric allows the freedom of placement of each compo-
nent and often results in an optimal one-stage reconstruction
that the operation proceeds smoothly; during flap dissection,
the blood pressure should be kept adequately low to keep a
bloodless field, but brought up gradually when hemostasis is
being secured and the anastomosis being performed to ensure
good recipient inflow and flap perfusion. Adequate fluid
management includes slight hemodilution to maintain high
cardiac output and low systemic vascular resistance.189
Special techniques and flap
modifications
Increasing familiarity with the principles and techniques of
microsurgery has encouraged various innovations and refine-
ments in the pursuit of excellence. The goal now is not only
simply to achieve closure, but to do so with the least amount
of donor morbidity, in the shortest operative time, and with
the best results in terms of function and appearance.
Endoscopic harvest
Endoscope-assisted harvest of free flaps allows the use of
smaller incisions and improved donor site appearance.
However this requires special instrumentation and a steep
learning curve that may initially increase the operative time.
Flaps harvested with endoscope assistance include gracilis,190
rectus abdominis,191 and latissimus dorsi192 muscle flaps,
temporoparietal fascial flaps,193,194 and jejunal segments.195
Although the complication rates are not dissimilar, incision
lengths are shorter, donor site morbidity and pain are reduced,
and patient satisfaction is higher when the flaps are harvested
endoscopically.
Robot-assisted free-flap surgery
The robot represents the most up-to-date technological inno-
vation in surgery. Its platform can provide high definition
12×–15× digital magnification, broader range of motion, fine
instrument handling with decreased tremor, reduced surgeon
fatigue, and improved surgical productivity.196,197 The role it
plays in urologic, gynecologic, cardiac, general, and endocrine
surgery is undisputable. However, in reconstructive microsur-
gery, the application of robots is still preliminary, but not
without potential. Transoral robotic surgeries have eliminated
lip- and mandible-splitting approaches and allowed the abla-
tion of tumors that have until recently been primarily treated
non-surgically.198 For the robot-created defects, a robot-assisted
free tissue transfer could be safely indicated but at the price
of prolonged surgery time.199 Other indications are recipient
vessel preparation, in particular the internal mammary vessels
for free-flap breast reconstruction,200 and free flap harvest, and
the latissimus dorsi, through minimal-access incisions.201
Usage in brachial plexus has also been described to improve
the surgery.202
Perforator flaps, free-style flaps, and
supramicrosurgery
A perforator flap is defined as a flap based on a musculocu-
taneous perforating vessel that is directly visualized and
dissected free from the surrounding muscle until adequate
pedicle length and caliber are obtained (Fig. 24.23). This
Fig. 24.23  Perforator flap harvest via an intramuscular dissection of the
perforators. *Perforator. *****Source artery of the perforators: descending branch
of the circumflex iliac artery. ----- Edge of the dissected vastus lateralis muscle.

465
Postoperative management, complications, and outcomes
Prelamination is another two-stage process where one or
more tissues are added to a reliable vascular bed to create a
multilayered composite flap. In the second stage, once matured
in approximately 2 weeks, the composite flap is transplanted
to the defect. This delayed procedure allows the best chance
for the prelaminating layers to heal, stabilize, and assume
their expected structures and positions. By laminating the
vascular bed with skin, bone, cartilage, or mucosa, prelami-
nated flaps have been used to reconstruct the oral lining,220
ear,221 nose,222,223 neourethra,224 penis,222 and trachea and
larynx.225
Postoperative management,
complications, and outcomes
The postoperative management of the patient is crucial in
preventing major morbidity and mortality. Patients should be
kept warm, adequately hydrated (hematocrit <0.3), and pain
free. Blood pressure should be normalized based on preopera-
tive blood pressure and tachycardia avoided as sympathetic
overdrive may cause vasospasm. Good hyperglycemic control
reduces the incidence of complications in the surgical patient
who may require insulin therapy. Prophylactic antibiotics
are routinely prescribed to prevent wound infection and
low-molecular-weight heparin is used to prevent deep vein
thromboses.
Monitoring
Monitoring begins on the re-establishment of blood flow into
the flap. The flap should constantly be assessed on release of
the microvascular clamps, during closure, on completion of
inset, when the patient transfers from the table, and on admis-
sion into the ward.226 Early detection and intervention of flap
problems can improve overall flap salvage.227–229 Although
many methods of flap monitoring are now available, none has
been completely effective or uniformly accepted. The ideal
monitor should be reliable, noninvasive, objectively repeat-
able, promptly reactive to blood flow changes, appropriate for
continuous monitoring in all types of free tissue transfers,
usable for the unskilled, and economically available.230
There is no substitute for experienced nursing and medical
staff, whether in a dedicated intensive care unit or on the
general ward. Clinical observation of the flap is the gold
standard for monitoring and should be performed at 30-minute
of compound defects209,210 (Fig. 24.24). Flaps that are microsur-
gically fabricated or linked are a subtype of chimeric flap that
allows multi-goal reconstruction,208 and they should be con-
sidered the “true chimera”. Finally, the concepts of conjoined
and chimeric flaps are also applicable to perforator-based
flaps.
Thinned flaps
Flaps that are thick and bulky often require a secondary revi-
sion in order to improve final outcome. However, with better
understanding of the vascular supply and from increasing
experience with perforator flaps, one-stage flap thinning has
become possible. Skin is nourished by a subdermal plexus
arising from branches of the main pedicle in addition to recur-
rent dermal branches and thinning can be performed safely
to about 3–4 mm in thickness in Asians, leaving an unthinned
area of 2 cm around the pedicle.211 This reduces the need for
secondary revisions.212 Another method of thinning is micro-
dissection of blood vessels in the adipose layer under micro-
scopic magnification and removal of the adipose tissue
surrounding the vessel213–215 (Fig. 24.25). The third method
that appears promising but still needs further anatomic inves-
tigations for wider application throughout the body is to
harvest the flap at the level of the Scarpa’s fascia with the
superficial circumflex artery perforator flap being the flap of
choice for this method.216
Prefabricated/prelaminated flaps
Some defects require complex reconstructions of various
components that cannot be met by conventional flaps. Flap
prefabrication and prelamination have been applied to
areas where specific contours and structures are desired, for
example, in reconstruction of the esophagus, penis, and
certain head and neck defects.
Prefabrication involves a two-stage process, the first of
which implants an axial vascular pedicle into the donor tissue
that is required,217 thus allowing it to be transferable once
neovascularization has occurred. The second stage, about 8
weeks after the implantation, involves the transfer of this
neovascularized tissue, based on its recently implanted
pedicle, to reconstruct the defect on its recently implanted
pedicle. This allows the creation of large, thin skin flaps that
retain the qualities of the donor site and can be modified with
various combinations of vascular pedicles, donor tissues, and
geographic locations for different clinical needs.218,219
Fig. 24.24  Chimeric flap with muscle and skin component.
Fig. 24.25  Thinning of a thick cutaneous flap. Image shows the edge of the flap
where flap has been excised safely to thin the flap according to requirements.

466
CHAPTER 24 • Principles and techniques of microvascular surgery
postoperative care of these patients during the first 72 hours
after surgery at the minimum.
Telemonitoring
The clinical inspection remains the gold standard in free flap
monitoring; however, it necessitates that the decision-maker
evaluates the flap him/herself to decide on take-back to the
operating theatre or “close eye-on” approach. To enhance
communication and make clinical inspection friendly yet
efficient, smart phones can be used. These carry-on devices
when integrated in flap monitoring showed comparable
accuracy rate but shorter response time compared with
in-person examination,241 which may increase salvage rate
and overall flap success rate,242 making the combined use of
smart phones and internet appealing and invaluable in the
modern era of digital technology.
Buried flaps
Monitoring buried flaps postoperatively is a challenge and
many techniques have been used to assess the flaps, either
directly or indirectly. Implantable Doppler probes have been
used routinely, as covered previously. However, due to high
sensitivity and positive-negativity, it could now be utilized as
a screening tool and a color Doppler can be used to confirm
the findings or avert unnecessary surgical exploration.243
Alternatively, color Doppler ultrasound can verify normal
arterial and venous flow through the pedicle, as demonstrated
in a functioning muscle transfer study.244
Part of the flap may be externalized. For example, a jejunal
stump may be brought to the surface to observe peristalsis
and color or a skin paddle may be externalized. This should
be used with some caution as this only monitors the common
source vessel and may not accurately reflect the buried com-
ponent, especially if the two components are based on differ-
ent perforators.245 The distal end of the pedicle that is usually
ligated close to the supply of the skin can also be externalized
and its pulsations observed directly under a transparent film
dressing. This can then be tied off in the follow-up clinic.246
Flap outcomes
With maturation of microsurgical technique, failures have
thankfully become rarer and success rates of free tissue trans-
fers now range from 96% to 100%.22,66 Failures can be attributed
to poor planning, poor choice of flap or vessels, poor timing,
or poor technique. However, many of the failing flaps may be
salvaged and the success of the salvage (54–100%111) is in part
dependent on good patient management, highly trained staff,
and early detection and intervention.
When a flap begins to fail, the likely causes must be identi-
fied and rectified. Although the majority of the complications
are related to vascular compromise, simple measures should
be taken by the bedside first to avoid unnecessary explora-
tions. Systemic factors such as hypotension, hypovolemia,
hypothermia, and sympathetic overdrive due to pain should
be resolved. Once the blood pressure is normalized and the
patient warmed up, the flap should be reassessed for the need
to return to the operating room. Local factors include the
release of external compression secondary to compressive
surgical dressing, hematoma, or a tight wound closure.
Releasing some sutures or loosening the dressings may relieve
intervals for the first 24 hours. This can be extended to 1–2-
hourly for the next 24 hours, then 4-hourly for the next 48
hours. Signs to be noted are color, capillary refill, turgor, and
surface temperature. If capillary refill is not obvious, pinprick
testing can be used to observe the color and speed of bleeding.
However, this pinprick should just scratch the dermis and not
penetrate too deeply and risk injury to the underlying pedicle.
This form of monitoring may not be as suitable for flaps in
aesthetically important areas. Surface temperature measure-
ment with a surface temperature probe is easy and inexpen-
sive231 and a recorded difference of 1.8°C between flap and
control sites is 98% sensitive and 75% predictive of vascular
compromise.232 The trend of the temperature of the flap over
time is also a useful guide to the failing flap226 and tempera-
tures below 30°C are indicative of flap failure.233
A hand-held pencil Doppler probe (low-frequency continu-
ous ultrasonography)231 applied on to the flap over a cuta-
neous perforator location is another method of monitoring.
This point should be marked intraoperatively away from
the pedicle to prevent false-positive results. An implant-
able Doppler probe can be used to monitor flaps without
a perforator to the skin or buried flaps.234 This small probe
is attached to a polymer sleeve that is placed around the
pedicle vessel (most accurate on the vein) adjacent to the
anastomosis with a probe lead wire exiting through the inci-
sion. This lead is removed by gentle traction which leaves
the sleeve in place when monitoring is no longer required.
The signals have a characteristic pattern that can differenti-
ate arterial from venous thrombosis. The method is sensitive;
however, it has a high false positive rate, resulting in frequent
intraoperative maneuvers to amend the cause of signal loss.
Some authors even reported on significantly more vascular
thrombotic events when compared to the non-flow coupler
group.235 Laser Doppler measures the reflected waveforms
of light, from a helium–neon laser, by the red blood cells
moving within the capillaries, and provides an objective
measurement for flap perfusion. Interpretation of the results
of laser Doppler requires experience but can be very accurate,
detecting vascular compromise with no false positives or nega-
tives236 and distinguishing venous obstruction from arterial
occlusion.237
Other available adjuncts less commonly used include pulse
oximetry to identify both a pulsatile flow and arterial satura-
tion in replanted or revascularized digits or toe-to-hand
transfers,238 photography, tissue oxygen tension measurement,
tissue pH levels, microdialysis, fluorescein dye mapping,
near-infrared spectroscopy, thermodilution technology, photo­
plethysmography, and nuclear medicine studies.239
In a recent survey of the members of American Society
of Reconstructive Microsurgery, a questionnaire concerning
perceptions and frequency of use of several technologies in
varied clinical situations revealed that hand-held Doppler
was the most commonly used technology; however, surgeons
were more willing to opt for immediate take-back to the
operating room based on concerning findings of tissue oxim-
etry compared with concerning Doppler signals.240 This sug-
gests that of all available adjunct technologies, tissue oximetry
may have the greatest impact on clinical decision-making in
the postoperative period.
Nevertheless, clinical monitoring remains the gold stan-
dard and, regardless of which adjunct is additionally used,
close flap monitoring should be a standard part of the

467
Postoperative management, complications, and outcomes
Most of the antispasmodic agents available are locally
applied to avoid systemic complications. The most commonly
used agents are papaverine, lidocaine, and calcium channel
blockers such as nifedipine, verapamil, and nicardipine.
Papaverine (30 mg/mL) is an opium alkaloid that functions
as a phosphodiesterase inhibitor and has a direct action on
smooth muscle through the release of cyclic adenosine mono-
phoshate. Lidocaine is a local anesthetic agent that has a
biphasic response with low and high concentrations potenti-
ating contraction and dilatation, respectively.254 Its vasodila-
tory mechanism remains unclear but is thought to be related
to sodium–calcium exchange pump. Some studies suggest
that its concentration should be increased up to 20% or be
combined with papaverine.255 The benefit of lidocaine contin-
ues after the drug is washed out with heparinized saline
solution and, as it is not significantly absorbed from the
wound, systemic effects are unlikely.256 In practice, however,
common concentrations of lidocaine used vary between 2 and
4%.257 Calcium channel blockers work by blocking voltage-
gated calcium channels in vascular smooth muscle. This
blocks the calcium influx required for muscle contraction and
may even be more effective than papaverine.258 Sympathetic
blockade using brachial plexus blocks has also been reported
to be effective.259–261
Mechanical treatments of vasospasm include gently dilat-
ing healthy vessel ends with a specially designed blunt-ended
vessel dilator forceps or with microneedle holders. Metallic
standard-sized dilators or intraluminal irrigation through the
passage of a fine intracath may also be used. This should be
done with caution, especially in arteriosclerotic vessels, as
catheters can strip endothelium and expose the thrombogenic
subendothelium.262 Surgical stripping of adventitia is an effec-
tive method of relieving vasospasm because of a sympathec-
tomy effect and mechanical thinning of the vessel walls allows
them to dilate more freely.263 If the spasm is intractable, the
vessel should be aggressively resected until normal vessel is
reached. Occasionally this may require an additional vein
graft or turning to another recipient vessel for anastomosis.
Stable and thorough anesthesia is an important require-
ment: hypovolemia, pain, and low core temperature (<36°C)
can all result in vasospasm. The patient’s temperature should
be constantly monitored and adequate hydration maintained,
and the wound should not be allowed to dry out.
Thrombogenesis
Many free-flap complications relate to pedicle thrombosis
(4–80% within the first 48 hours) caused by changes in the
intraluminal blood flow, endothelial damage, and the state
of coagulability. Changes in flow can be due to external
mechanical compression from bandages, closure of the
wound under tension, the weight of the flap, tension, twist-
ing, kinking, or vasospasm of the vascular pedicle after the
anastomosis is completed. Intraluminal turbulence may be
caused by irregularities in the intima from technical error,
suture material, and the result of size mismatch.
Hypercoagulability may be systemic or local. Hypercoagu-
lable states such as pregnancy, active cancer, and recent
trauma should be identified preoperatively as far as possible
and warrant thromboprophylaxis. Hypercoagulation disor-
ders like activated protein C,264 hyperfibrinogenemia,265
antiphospholipid syndrome,266 and reactive thrombocytosis267
the compression, solving the problem or at least temporizing
the immediate threat to the flap before the formal salvage
procedure. If the flap does not improve, a bedside exploration
of the vessels can be performed to relieve vessel twist or kink,
to assess the patency of the microanastomosis, and to open
the pedicle second-vein to resolve ongoing congestion. After
that, a prompt return to the operating room is mandatory in
the evidence of thrombosis. Resection and reanastomosis or
the use of a Fogarty thrombectomy247 may be required. Intra-
operative lysis with urokinase or tissue-type plasminogen
activator may also help.248–250
Causes of a failing flap
Anastomotic failure
There are many causes of anastomotic failure, such as those
related to technical errors in the anastomosis, or intrinsic
factors predisposing to vasospasm or thrombogenesis.
The principal faults leading to anastomotic failure are
tearing, leaking, narrowing of the lumen, through-stitching,
and inclusion of the adventitia.37 Tearing occurs when there is
too much tension at the site of the repair. It can also be caused
by too meticulous stripping of adventitia: the veins of the
head and neck region are especially fragile. Leaking occurs
when there is too big a gap between sutures, or there is a tear
or a tiny unnoticed branch near the anastomotic site. Even a
small leak will precipitate intraluminal thrombus formation251
and narrowing of the lumen can also be caused by oversized
bites, entangling knots with one another, or continuous sutur-
ing that is too tight. Through-stitching entails taking a bite of
the back wall with the suture, causing luminal obstruction.
This can be avoided by always visualizing the lumen of the
vessel through constant luminal irrigation by an assistant or
by raising the anterior wall with the tops of microforceps to
separate it from the back wall. Inclusion of adventitia as a
result of inadequate vessel preparation should be avoided as
the prolapsed adventitia is another nidus for thrombus forma-
tion. Finally, desiccation of the vessel may also lead to failure.
Vasospasm
Vasospasm occurs in 5–10% of microsurgical procedures and
plays an important role in the pathogenesis of hypoperfusion,
promoting thrombosis, which may lead to partial or total flap
loss. It may be seen intraoperatively and up to 72 hours
postoperatively, with the former often being more problem-
atic. The pathophysiology of vasospasm is not clear, but is
thought to occur secondary to both general and local factors.
General factors include low core temperatures, hypotension,
and sympathetic response to pain, while local factors include
trauma to the vessel, tight adventitia, myogenic response to
local hemorrhage, desiccation of the tissues, and vascular
disease. Surgical dissection may induce sympathetic nerve
endings to release vasoactive compounds, and impair release
of vasodilators,252 compounding the vasospasm and thrombo-
sis. Veins appear to be less susceptible to vasospasm than
arteries but, once established, harder to resolve253 and more
detrimental.
If the vessel is left untouched for a few minutes, it may
vasodilate to its natural diameter. However, a variety of
antispasmodic agents or mechanical dilation can be used to
aid relief of the vasospasm.

468
CHAPTER 24 • Principles and techniques of microvascular surgery
administered at high concentrations44,283,284 while minimizing
the systemic complications. Heparin binds to the endothelium
and has a half-life of 5 hours285 and should be applied as soon
as the vessels are divided. Clinically, however, Khouri showed
no increase in patency regardless of concentration111 and Yan
suggested that high-pressure local irrigation might even cause
intimal and endothelial damage.286 Nevertheless, together
with another important side effect of heparin-induced throm-
bocytopenia, systemically administered heparin should be
used judiciously.
Dextran is a polysaccharide synthesized from sucrose and
produced synthetically as a 40- or 70-kDa molecular weight
polymer. Its antithrombotic effect is mediated through increas-
ing the electronegativity of erythrocytes, platelets, and endo-
thelium and therefore platelet aggregation, decreasing factor
VIII-Ag and thereby platelet function and fibrin structure,
and, finally, as a volume expander that reduces blood viscos-
ity. Dextran-40, the more popular dextran for anticoagulation
in microsurgery,111,281,287 is excreted more effectively by the
kidneys and has a shorter action than dextran-70. No random-
ized controlled studies have shown a cause-and-effect rela-
tionship between the use of dextran and flap loss or prevention
of thrombosis. In particular, it has not been shown to be more
effective than other anticoagulants and its benefits of improved
vessel patency are not seen beyond a week.288,289 Although it
has relatively few side effects, these can be serious and include
anaphylaxis, volume overload, pulmonary or cerebral edema,
platelet dysfunction, and even acute renal failure.290,291 A
comparison of dextran and aspirin-related complications in
head and neck patients with free-flap reconstructions showed
that both were equally effective in preventing flap failure, but
dextran was associated with a 3.9- and 7.2-fold increased rela-
tive risk of systemic complications after 48 and 120 hours of
dextran infusion, respectively.292
Aspirin is an antiplatelet agent that inhibits cyclooxygenase
and reduces the breakdown of arachidonic acid to thrombox-
ane, a potent vasoconstrictor and platelet aggregator, and
prostacyclin, a vasodilator that inhibits platelet aggregation.
Low-dose aspirin (75 mg/day) has been shown to inhibit
thromboxane selectively at the site of the anastomosis293
while preserving prostacyclin production of the endothelium.
Experimentally, it has been shown to improve anastomotic
patency and capillary perfusion and may be related to the
timing of administration.294,295 It is, however, less effective
than heparin295,296 and, despite the lack of clinical evidence for
its effect on free-flap patency, it is still used widely. The
adverse effects of aspirin such as gastric hemorrhage, renal
failure, and prolonged bleeding are a direct result of the
mechanisms that make its use attractive in microsurgery and
have been minimized with the use of low-dose aspirin. The
newer cyclooxygenase II inhibitors are also associated with
fewer renal and gastric side-effects but do not prevent platelet
aggregation and are therefore not used in microsurgery.297
Prostaglandin E1 is known for its application in peripheral
arterial occlusive disease. It has long-standing anti-ischemic
and tissue-protecting effects against ischemia–reperfusion
injury. It is capable of relieving microvascular spasm and
increases deformability of red cells; in addition to the positive
impact on blood flow, viscosity, and platelet aggregation.298
Thrombotic diathesis can be reduced by using a low dose in
arterioles, or a high dose in venules.299 It is commonly used in
replantation, toe-to-hand microsurgical transplantation, and
should be treated preoperatively, although routine screening
for these is not cost-effective. Thromboplastins are soluble in
water and present in abundance in the surgical wound. When
blood is contaminated by this, clotting will occur and periodic
irrigation with heparinized saline will minimize this risk.
Even a smooth and streamlined microvascular anastomosis
will produce some thrombus, and when blood flow is restored,
the thrombus continues to grow for 5 minutes, starts to disin-
tegrate by 10 minutes, and disappears nearly completely by
the end of an hour. If the anastomosis is irregular, the throm-
bus will grow rapidly and occlude the vessel. Endothelial cells
are critical in local blood flow control and produce vasocon-
strictors such as endothelin-1268,269 and vasodilator substances,
nitric oxide and prostacyclin. Damaged endothelium produces
a highly thrombogenic state, resulting in platelet aggregation
and the initiation of a complex clotting cascade, and surgical
precision is vital to minimize vessel damage.270
The risk of thrombosis is greatest within the first 48 hours
and decreases to 10% after 72 hours.229 Arterial and venous
thrombi present at different times and form through different
mechanisms. The majority of arterial thromboses occur during
the first 24 hours and are related to platelet aggregation at the
anastomotic site.271 Venous thrombosis is more often respon-
sible for flap compromise, presents later, and is related to the
formation of a fibrin clot. The goals of anticoagulant prophy-
laxis are therefore to interfere with platelet function and
aggregation, counter the effects of thrombin on platelets and
fibrinogen, and reduce blood viscosity or increase blood
flow.272 While the use of anticoagulants to lower the incidence
of anastomotic thrombosis is widely practiced, literature
regarding the efficacy of one treatment over another is sparse
and largely based on the individual surgeon’s preference and
preconceptions. Protocols differ not only in the agents used,
but also the dose, combination, timing, and duration. Heparin,
dextran, and aspirin are the most commonly used prophylac-
tic antithrombotics today.
Heparin reduces platelet aggregation, activates antithrom-
bin III (thereby directly deactivating clotting factors II, IX, X,
XI and, indirectly, factors V and VIII), lowers blood viscosity,
and has direct vasodilatory properties.273 This polyglycosami-
noglycan was the first anticoagulant described and has been
in clinical use for over 50 years to prevent both arterial and
venous thromboses, even at subtherapeutic levels274 and
independent of rate of blood flow. As a washout solution, it
may have a protective effect against ischemia/reperfusion
injury through a direct effect on microvascular endothelium.275
Intravascular heparin improves flap salvage rates276 and clini-
cally reduces the rate of thrombotic events.111 Its use, however,
may be more important in patients with atherosclerotic or
injured vessels, when vein grafts have been used and with
thrombosis of an anastomosis, than in patients with healthy
vessels and straightforward anastomoses.277 The use of intra-
vascular unfractionated heparin may increase the risk of
hematoma formation,278,279 but both Chien et al.280 and Kroll
et al.281 have found that flap survival was equivalent to that
with other regimens without increased incidence of hema-
toma. Low-molecular-weight heparins, which inhibit clotting
factor Xa with less of an effect on thrombin inactivation, may
be just as effective in improving patency without the risk of
hematoma formation.282 Unfractionated heparin is used uni-
versally to irrigate vessels during microvascular surgery and
has been shown experimentally to improve patency when

469
Postoperative management, complications, and outcomes
prolonged beyond 3 hours or to the point of “no-reflow
phenomenon”.
While the goal of microsurgical anastomosis is to restore
flow and reperfuse the flap, after a prolonged period of ische-
mia, this reperfusion may compound insult to the flap through
local and systemic inflammatory responses. This is known as
ischemia–reperfusion injury and is thought to be a result of
the buildup of oxygen radicals during the ischemic period.
These cause tissue injury, specifically of cellular membranes
through their powerful oxidizing and reducing potentials.
They also stimulate an intense inflammatory reaction by
recruiting inflammatory cells such as leukocytes, neutrophils,
and platelets, and other inflammatory mediators and cyto-
kines,313 while suppressing protective molecules such as nitric
oxide synthase, prostacyclin, and thrombomodulin. In clinical
free flaps, a similar pathophysiology was also found. From
a histological and molecular point of view, significant
up-regulation of inflammatory parameters, in particular
interleukin-1β and tumor necrosis factor α, infiltration of
inflammatory cells, and angiogenesis were documented.
Increased complement component 3 deposition and apoptosis
of cells were accompanied by interstitial edema as indication
for a pronounced postischemic inflammatory reaction within
the muscle tissue after free tissue transfer.314 In cutaneous
flaps, a significant decrease in total hydrophilic antioxidant
capacity (TEAC) was seen.315 These findings provided insights
into some effective treatment modalities to minimize the
damage induced by ischemia–reperfusion injury as discussed
below.
Severe ischemia–reperfusion injury results in irreversible
vasoconstriction, and the resulting inability to reperfuse the
flap despite patent anastomoses is known as the “no-reflow
phenomenon”.316 This is a result of ischemia-induced endo-
thelial injury, which leads to cellular swelling, interstitial
swelling, exposure of subendothelial collagen, platelet–
leukocyte aggregation, reduction in blood flow and, if not
rectified, thrombosis and flap failure.
Experimental studies have shown a protective function
of intravascular administration of heparin,275,317 vasodilators,
prostaglandin E1, nitrendipine and prostacyclin, thrombolytics,
urokinase and streptokinase, nonsteroidal anti-inflammatory
drugs, and free radical scavengers deferoxamine and super­
oxide dismutase.318,319 Inhibiting the action of selectins, inte-
grins, and intercellular adhesion molecules with monoclonal
antibodies to prevent inflammatory cell adhesion may also
prevent ischemia–reperfusion injury, but these have not
translated clinically.320,321
Clinically, few pharmacological agents have been used and
proved promising. One treatment modality aimed at increas-
ing microcirculation within the transverse rectus abdominis
muscle flap by continuous IV administration of arginine
showed significant improvement in zone IV perfusion.322
While the other aimed at reducing the inflammatory response
and the interstitial edema by applying negative wound
therapy on top of the skin grafted muscle flaps with remark-
able reduction in interleukin-1β and tumor necrosis factor α
in biopsies.323 The last targeted the endothelial dysfunction
using statins drawing on their pleiotropic effects;324 however,
a larger study failed to show clear advantages of the statins
or other cardiovascular medications in ischemia–reperfusion
injury.325 So, the benefit of statins remain theoretical, and their
usage is limited to patients with cardiovascular diseases.
other free flap transfer. Despite the promising results reported
earlier, a large study analyzing whether prostaglandin-E1
(PGE1) and dextran-40 can improve the outcomes compared
to no-antithrombotic therapy in head and neck reconstruction
revealed no significant difference among PGE1, dextran-40,
and control group in flap survival.300 Other antithrombotic
agents tested in animal models to determine their efficacy in
augmenting flap survival include pentoxifylline,301 hirudin,284
nonsteroidal anti-inflammatories,302,303 other antiplatelets such
as dipyridamole and ticlopidine.304
Thrombolytics such as streptokinase, urokinase, and tissue
plasminogen activator have been advocated for flaps not
responding to standard salvage techniques248 and may be
effective in reversing microvascular thrombosis,249,250 but clini-
cal evidence is sparse and anecdotal.305–308 A retrospective
multi-institutional study even reported no significant
improvement in patency with the use of thrombolytic therapy
in free-flap salvage.309 Streptokinase enhances the conversion
of plasminogen to plasmin with subsequent fibrinolysis,
whilst urokinase and tissue-type plasminogen activator,
which activate plasminogen directly, are less antigenic and
have fewer systemic effects. There is a significant risk of
bleeding following systemic exposure to thrombolytics but
this can be minimized by local intra-arterial administration of
the thrombolytic and drainage of the venous effluent.310
When surgical and pharmacological salvage fails, medici-
nal leeches (Hirudo medicinalis) have been used effectively to
treat venous congested flaps.311 When applied to the flap, they
bite into it, injecting a local anesthetic, vasodilator, and anti-
coagulant, hirudin, which is present in their saliva. Leeches
increase perfusion within congested flaps by feeding on the
blood. They then fall away when full, but the bleeding con-
tinues for up to 10 hours with the combination of vasodilator
and anticoagulant.312 New leeches can be applied when the
bleeding slows or the flap appears congested again. Therapy
is continued until the flap re-establishes an effective venous
drainage through new vessel ingrowth around the flap
margins. As there can be significant blood loss with leech
therapy, this is usually limited to small- to medium-sized flaps
and the patient’s hemoglobin should be monitored daily.
Prophylactic antibiotics should also be given against Aeromo-
nas hydrophila from the leeches’ digestive tract.
Ischemic tolerance, ischaemia–reperfusion injury, and
no-reflow phenomenon
Prolonged periods of warm ischemia (the time between inter-
ruption and re-establishment of the circulation) concern
microsurgeons as they predispose to tissue necrosis and flap
failure. Primary ischemia occurs when the anastomosis is
being performed and can be kept to a minimum by donor site
and vessel preparation before flap pedicle division and an
accurate anastomosis, whilst secondary ischemia occurs later
as a result of pedicle obstruction.
The tolerance to ischemia varies from tissue to tissue
depending on their metabolic requirements, with skin, nerve,
bone, muscle, and then intestine being decreasingly tolerant.
Within a composite flap, the overall tolerance is equal to that
of the least tolerant component. A study of 700 free flaps failed
to show a statistical difference in ischemic times between
successful and failed flaps and concluded that ischemic time
was irrelevant to flap survival provided ischemia was not

470
CHAPTER 24 • Principles and techniques of microvascular surgery
attempt with another free flap. Examples include technical
errors, suboptimal postoperative management, and delay in
diagnosis and salvage. Irreversible patient factors like sys-
temic vascular disease, radiation injury, and lack of healthy
recipient vessels do not preclude a further attempt but the
decision to proceed with a second microsurgical reconstruc-
tion should be weighed carefully against the risks. If the
risks outweigh the benefits, a nonmicrosurgical procedure
may be the sensible option, although this may be just as
complicated.
The need for further reconstruction is then evaluated.
Factors to be considered include the extent of the failure,339
exposure of vital structures, and the effect of an open wound
on subsequent therapy. An important question to address
is whether the initial goal of a sophisticated reconstruction
should be pursued or if a downgraded reconstruction is an
acceptable compromise between achieving wound closure
and the aesthetic and functional goals. Partial loss of a flap
secondary to necrosis may be amenable to conservative treat-
ment with conventional dressings, vacuum-assisted closure,
or skin graft. Complete failures, such as those due to arterial
insufficiency, are more catastrophic and require more aggres-
sive treatment while venous failures deserve a more expectant
management with the use of medicinal leeches or by allowing
the flap to bleed out slowly to allow partial salvage. This
may support a skin graft after tangential debridement.339 If
the flap loss results in exposure of vital structures such as
the great vessels of the neck, skull base, metal plates or bare
bone, the situation may be life-threatening and mandates
prompt coverage with another flap.340 For breast recon-
struction, it is reasonable to consider primary or secondary
closure if the patient can accept the cosmetic implications. In
extremity reconstruction, where the threat is isolated to the
extremity involved, a more expectant approach can be taken,
provided metal plates or vital structures are not exposed.
Less aggressive management may, however, result in higher
rates of limb amputation.341 In oncological reconstruction,
the primary goal is uncomplicated wound healing in order
that adjuvant therapy can proceed. In these circumstances
a second flap will expedite wound healing and should be
considered early. A pedicled muscle or cutaneous flap might
be a reasonable alternative to a free flap, if the factors involved
are irreversible or the risk of a second free flap outweighs the
benefits.
Once the decision has been made to proceed, the course
of action needs detailed planning. Factors to be considered
include the timing of the repeat surgery, the type of recon-
struction required for the resulting defect, and if there is a
need for a second free flap. If a second free flap is needed,
then what donor sites are available and what recipient
vessels can be reliably dissected and safely used? Impor-
tantly, are the goals of reconstruction the same as they were
initially?
The timing of the surgery is dependent on several factors.
If the patient is unstable, then reoperation is ideally delayed.
Infection-free, the flap may act as a temporizing biologi-
cal dressing until the patient is fit for further surgery. The
recipient site and exposure of vital structures may dictate
the urgency of the surgery. If the patient is fit enough, the
same second free flap should be performed at the time of
adequate debridement.25 In our experience of 101 failed free
flaps, 34% received a second free flap340 and we feel a second
Donor site complications – dependent again
on flap choice
Every flap harvested leaves a donor site of varying morbidity;
therefore, the benefits of the reconstruction must outweigh its
sequelae. The incidence of donor site complications varies
between 5.5% and 31%, with early donor problems associated
with wound healing (hematoma, seroma, and wound dehis-
cence).326,327 These are more likely in obese patients, diabetics,
and smokers. Hematomas may occur with any flap harvest
and meticulous hemostasis with a normotensive (for the
patient) blood pressure must be performed. Seromas occur
when extensive dissections leave large dead spaces, for
example, with a latissimus dorsi or deep inferior epigastric
perforator harvest, and wound dehiscence occurs with tight
closure, which can be avoided with good preoperative
planning.
Long-term problems are usually that of poor cosmesis,
reduced function, and chronic pain. If the donor site has to be
grafted, this causes a significant cosmetic disadvantage and
patient dissatisfaction.327–330 Suprafascial dissection reduces
the size of the donor defect, allows preservation of the super-
ficial nerves, prevents tenting of tendons, and improves skin
graft take. This allows a full-thickness skin graft with superior
cosmesis to be applied with confidence and reduces potential
tendon exposure from delayed healing.330–332 Muscle flaps may
cause weakness and functional impairment; for example,
serratus anterior muscle elevation may cause scapular winging
and the TRAM flap is associated with hernia formation.333,334
Harvesting vascularized bone may result in impaired func-
tion of a fracture-susceptible donor site, requiring troublesome
splinting for a prolonged period,326,335 and even affecting gait.
Cutaneous nerves may be sacrificed, leaving painful neuro-
mas or unacceptable numbness.335–337 Temporary or permanent
palsies may result from injured motor nerves and compart-
ment syndrome from overzealous closures.338
Management of failed flaps
Flap failure has profound implications on both patient and
surgeon and represents one of the most challenging aspects
of reconstructive microsurgery. Despite the increased expe-
rience and refinements in microsurgical techniques and
perioperative management, a small number of flaps still
fail. With the low incidence of flap failure, there are few
articles in the literature that address the management of flap
failure and no guidelines regarding the best approach to this
problem exist.
Many questions are raised immediately when a flap fails.
Why did it happen? What defect requires reconstruction?
How and when should the defect be reconstructed? These
questions invariably form the basis of a systematic approach
to the problem at hand and should be considered when
managing a failed flap. Analyzing 54 failed flaps, Oliva et al.25
recommend that three issues must be considered when the
initial flap is declared nonviable – the reasons for failure, the
indications for the free-flap reconstruction, and the current
status of the resultant wound.
It is important to identify the reasons for the failure as
subsequent attempts at reconstruction might be plagued
with the same issues and be doomed to fail. If the cause is
reversible or preventable, then this bodes well for a repeat

471
The future of microsurgery
Google Glass or any similar products with live streaming
of the surgical procedures utilizing the 4G or high-speed
internet may help in telesupervision of trainees for a safer
hands-on training experience.
Other technological advancements in the fields of high
definition magnification and imaging can improve our under-
standing of the fine circulation of skin, muscles, bones, etc.,
resulting in custom-designed free tissue transfer; an even
more refined form of supermicrosurgery.
Robots are already in use, but a specialized microsurgery
robot is still lacking, which could be a product of the future;
however, the wide application of robotic surgery may not
witness significant change not only because of its cost but also
due to limited indications.
How about the technical part itself, such as the microanas-
tomosis, the dissection techniques, inset, etc? While the
standard techniques described in the chapter will remain in
use heavily, the trend towards sutureless and minimal-access
surgery (in other words, a traumaless approach) will most
likely continue to grow.
As for flaps and donor sites, we believe that every micro-
surgeon or center will have their own workhorse flaps that
they rely on to achieve the reconstruction goals; however, free
flaps from the lower extremity will most likely prevail over
other flaps for the advantages of two-team approach and
diversity of options.
Many authors have already mentioned that vascularized
composite tissue allotransplantation (VCA) is the frontier to
conquer, and it could be the future of microsurgery! We do
not very much share that vision. This is because microsurgery
is a technique utilized in the field of VCA not the opposite.
Second, the main obstacle to broader application of VCA is
immunosuppression not microsurgery. Although hand trans-
plantation is not “another replantation”, it relies on the same
techniques used in replantation and toe-to-hand surgery. And
face transplantation has its roots in facelift techniques and
facial trauma and orthognathic surgery. So, the techniques are
already established, and only a breakthrough in immunosup-
pression will lead to a revolution in VCA. Hand transplanta-
tion recorded number one in VCA may lose ground with the
development of smart prosthesis. However, face transplanta-
tion may witness a flourishing future since results are encour-
aging and no alternative option is available, not to mention
the increase in war casualties among civilians nowadays.
Finally, our words to history; microsurgery will not decline:
the growing interest in learning microsurgery and the lack of
comparable techniques will ensure this. Furthermore, micro-
surgery may become an independent specialty instead of a
set of skills used by different specialties, but mainly plastic
surgery. And technological refinements and breakthroughs
will definitely shape the theme of future microsurgery.
free flap should be attempted in any case in which failure
may lead to loss of the injured limb, leave exposed major neck
vessels, or cause delay in adjuvant chemo- or radiotherapy.
Restoration of function should also be attempted in a previous
functional muscle transfer. The success rate of second free
flaps is higher in the head and neck region (94.1%) compared
to that in the extremity (82.2–87.5%).340,342 A downgrade of
reconstruction should only be considered if the patient is
not in optimal condition or in the presence of overwhelming
infection as this often results in poorer cosmetic and functional
outcomes.
The second free flap needs to be chosen and designed care-
fully. It should have good vascularity and a longer pedicle as
debridement may leave a larger defect, and the new recipient
vessels are likely to be further from the defect. Where possible,
do not reuse the previous recipient vessels as they are likely
to be inflamed and friable. Interpositional vein grafts may be
required but have been associated with a higher incidence of
flap failure and vascular complications.343,344 If the same flap
is available on the contralateral side, this is our flap of choice
and was most commonly used.340 However, as it is generally
accepted that a flap with an osseous component poses addi-
tional difficulties during flap elevation and inset and has been
associated with a higher failure rate,133 a safer option should
be considered. Other indications for choosing a different type
of flap (for example, choosing a myocutaneous, fasciocutane-
ous, or even pedicled flap with reconstruction plate over an
osteocutaneous flap) include the absence (abdominal flaps) or
unavailability of the contralateral side (already used or in the
zone of injury) or a downgrading of the reconstructive goals
due to patient fitness, altered prognosis, or the need to ensure
survival.
The future of microsurgery
Has microsurgery reached a status quo yet? Or, will innova-
tions and breakthroughs continue to endure? The authors
believe that there are no definite answers to these questions;
however, there could be a good chance to make a better use
of microsurgery in future by proper planning and smart
investment.
The following potential directions reflect some of the
authors’ ideas on microsurgery in the digital era.
Digital technology is always evolving and will most likely
continue to evolve. Intertwining technology and microsurgery
together will be a “game changer” in our practice.
Smart phone apps may revolutionize free flap monitor-
ing345 and probably the whole perioperative workup by
providing surgeon-friendly, fast, and, efficient tools for com-
munication, assessment, and advice.
3. Tamai S. History of microsurgery – from the beginning until the
end of the 1970s. Microsurgery. 1993;14:6–13.
9. Kriss TC, Kriss VM. History of the operating microscope: from
magnifying glass to microneurosurgery. Neurosurgery.
1998;42:899–907.
16. Anonymous. Replantation surgery in China: Report of the
American Replantation Mission to China. Plast Reconstr Surg.
1973;52:476–489.
19. Antia NH, Buch VI. Transfer of an abdominal dermo–fat graft by
direct anastamosis of blood vessels. Br J Plast Surg. 1971;24:15–19.
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225. Vranckx JJ, Den Hondt M, Delaere P. Prefabrication and
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226. Jones NF. Intraoperative and postoperative monitoring of
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228. Goodstein WA, Buncke HJ Jr. Patterns of vascular anastomoses vs.
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229. Kroll SS, Schusterman MA, Reece GP, et al. Timing of pedicle
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230. Jones BM. Monitors for the cutaneous microcirculation. Plast
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231. Disa JJ, Cordeiro PG, Hidalgo DA. Efficacy of conventional
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232. Khouri RK, Shaw WW. Monitoring of free flaps with surface–
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235. Kempton SJ, Poore SO, Chen JT, Afifi AM. Free flap monitoring
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472.e6
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247. Wheatley MJ, Meltzer TR. The role of vascular pedicle
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249. Cooley BC, Jones MM, Dellon AL. Comparison of efficacy of
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251. Olsson E, Sarlomo-Rikala M, Bohling T, et al.
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264. Arnljots B, Soderstrom T, Svensson H. No correlation between
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266. Salgarello M, Cervelli D, Barone-Adesi L. A massive arterial
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272. Ketchum LD. Pharmacological alterations in the clotting
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273. Tangphao O, Chalon S, Moreno HJ Jr, et al. Heparin–induced
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274. Stockmans F, Stassen JM, Vermylen J, et al. A technique to
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275. Li X, Cooley BC, Fowler JD, et al. Intravascular heparin protects
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276. Kirschner RE, Xu J, Fyfe B, et al. Salvage of free flaps after
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277. Pederson WC. Clinical use of anticoagulants following free tissue
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278. Hemker HC, Beguin S, Kakkar VV. Can the haemorrhagic
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279. Pugh CM, Dennis RH 2nd, Massac EA. Evaluation of
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280. Chien W, Varvares MA, Hadlock T, et al. Effects of aspirin and
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281. Kroll SS, Miller MJ, Reece GP, et al. Anticoagulants and
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282. Ritter EF, Cronan JC, Rudner AM, et al. Improved microsurgical
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283. Chen LE, Seaber AV, Korompilias AV, et al. Effects of enoxaparin,
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284. Fu K, Izquierdo R, Walenga JM, et al. Comparative study on the
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286. Yan JG, Yousif NJ, Dzwierzynski WW, et al. Irrigation pressure
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25 
Principles and applications of
tissue expansion
Ivo Alexander Pestana, Louis C. Argenta, and Malcolm W. Marks
SYNOPSIS
■ Tissue expansion is a time-tested and simple technique to generate
tissue to reconstruct defects.
■ The technique stretches skin and soft tissue that have the same color
and texture as the adjoining skin where expanded tissue is needed.
■ In the breast, expansion is particularly useful in stretching existing
anatomy to accommodate a permanent prosthesis.
■ Tissue expansion principles may be combined with other
reconstructive techniques to provide a safe and individualized
reconstructive plan for complex bodily defects.
Introduction
The plastic nature of the human integument can be witnessed
whenever the skin must allow for growth underneath it. The
surgeon can take advantage of this plasticity when either
medical need or aesthetic surgery would benefit from the
creation of new autogenous skin. Just as development of a
fetal brain will cause the overlying skull to grow, growth
of the skeleton causes all normal skin and soft tissues that
envelope the bone to respond and expand. Similarly, the
growth of other structures inside the body will cause skin
and subcutaneous tissues to expand as demonstrated by the
serial growth of the abdomen with successive pregnancies.
Whether the growth is caused by benign or malignant tumors
under histologically normal skin or is experienced in the
gravid abdomen, there is a clear response to non-genetic
stimuli allowing necessary growth to accommodate underly-
ing structures.
Since its introduction, the benefits of tissue expansion have
produced a significant evolution of therapeutic techniques
since donor tissue may be generated in situ and used for
reconstruction without compromise of innervation, vascular-
ity, or external physical appearance. One of the critical benefits
of tissue expansion is the fact that there are various methods
for expansion of skin, bone, and other tissues. Placement of a
prosthesis under soft tissues allows the surgeon to gradually
add saline and expand subcutaneous and cutaneous tissues.
External hardware is used to gradually expand fractured bone
through the application of distraction forces. These techniques
have been applied to the craniofacial skeleton as well as to
most of the long bones of the body.1,2 Similarly, negative pres-
sure wound therapy (NPWT) uses the principle of applying
mechanical force to cells surrounding a wound to stimulate
the induction of new tissue that will subsequently aid in
closure of that wound.3
Access the Historical Perspective section online at

Basic science
Cellular and molecular basis for tissue
expansion
The application of mechanical stress to living tissues and cells
affects various cell structures and signaling pathways that are
highly integrated (Fig. 25.1).15 These closely integrated cas-
cades are theorized to explain the generation of new tissue
through mechanical stimulation.16 Several in vitro stretching
systems have been used to better understand the molecular
events that occur.17 Mechanical deformation forces involve
several cellular mechanisms including the cytoskeleton
system, extracellular matrix, enzyme activation, secondary
messengers, and ion channels.
The cytoskeleton plays a critical role in mediating the
transformation of extracellular mechanical force to intracel-
lular events. A system of microfilaments within the cytoplasm
not only maintains intracellular tension and cell structure but
also transduces signals to adjacent cells and initiates transduc-
tion cascades within the cell (Fig. 25.2).16 Protein kinase C
plays a pivotal role in signal transduction. Mechanical strain
  Access video lecture content for this chapter online at expertconsult.com

473.e1
Historical perspective
Historical perspective
In 1905, Codvilla applied the principles of using an external,
distractive force to encourage tissue expansion in bone.4 Bone
tissue regeneration was later documented in 1970 by Ilizarov
and others, who provided roentgenographic and morphologic
data from experimental distraction epiphysiolysis.2 Shortly
thereafter, Matev reported the expansion of bony tissue after
amputation of the thumb at the metacarpophalangeal joint.5
In the meantime, physicians began to recognize the induc-
tion of new soft-tissue growth adjacent to the bony structures
undergoing gradual lengthening. In 1957, Neumann implanted
a subcutaneous balloon to induce soft-tissue growth purpose-
fully for the reconstruction of an external ear deformity.6
Unfortunately, his report was considered anecdotal so pro-
gress in surgical soft-tissue expansion was delayed until the
1982 reports of using implanted silicone balloons to expand
overlying soft tissue were published.
Radovan7 and Austad8 and Rose9 simultaneously devel-
oped the concept of implanting silicone balloons as expanders.
Austad’s prosthesis was a self-inflating device that used
osmotic gradients driven by salt placed within the expander.
His largely experimental work was critical to elucidating the
physiology of tissue expansion.
Radovan’s device contained a self-sealing valve through
which saline was periodically injected to increase the size of
the expander. His work was initially greeted with skepticism.
Despite this, Grabb’s enthusiastic acceptance of Radovan’s
technique stimulated its rapid and wide application to create
new horizons in reconstructive surgery.10–14 Large studies
subsequently confirmed the safety and efficacy of this
technique.

474
CHAPTER 25 • Principles and applications of tissue expansion
expression with resultant changes in cytokine/chemokine/
growth factor expression and matrix metalloproteinase
expression. In human and animal models, increases in anti-
inflammatory cytokines (Il-10) and pro-angiogenic growth
factors (VEGF, FGF, PDGF) have been demonstrated with
the use of NPWT. The above, in conjunction with reduction
in MMP expression, indicates that NPWT may promote
healing by modulation of cytokines to an anti-inflammatory
profile and alteration in mechanoreceptor and chemorecep-
tor mediated signaling to culminate in angiogenesis and
on cell walls activates inositol phosphatase, phospholipase A2,
phospholipase D, and other messengers. Activation of these
components leads to activation of protein kinase C, which
suggests that intracellular signals can be transmitted to the
nucleus. Protein kinase C activation has been noted in human
cells subjected to strain in vitro.16
The mechanical effects of negative pressure wound
therapy (NPWT) on wounded tissues and their subse-
quent cellular and molecular effects are actively being
studied. At a cellular level, NPWT alters wound bed gene
Fig. 25.1  Effects of tissue expansion on surrounding
tissue. Strain-induced responses are mediated by growth
factors such as platelet-derived growth factor (PDGF) that
are known to stimulate cutaneous cell proliferation. Other
growth factors such as transforming growth factor-β
(TGF-β) may stimulate extracellular matrix production.
Membrane-bound molecules including protein kinase
play a key role in regulating intracellular signaling
cascades. EGF, epidermal growth factor. (Adapted from
Takei T, Mills I, Arai K, et al. Molecular bases for tissue
expansion: clinical implications for surgeon. Plast
Reconstr Surg. 1998;102:247–258.)
Tissue expander
Growth factors
EGF, PDGF
Extracellular matrix
Cell membrane
Cytoskeleton
Focal adhesion plaques
Molecular effects
Subcutaneous
Dermis
Epidermis
TGF-β
Stretched
Fig. 25.2  Schematic of possible signal transduction
pathways induced by mechanical strain. Transduction
pathways are activated by numerous strain-induced
signals transmitted through various membrane receptor or
membrane ion channels. Terminal enzymes that are
activated by these intracellular cascades transduce these
signals into the nucleus. cAMP, cyclic adenosine
monophosphate; DAG, diacylglycerol; IP3, inositol
1,4,5-triphosphate; JNK, c-Jun amino-terminal kinase;
MEKK/MEK/MAPK, mitogen-activated kinases; PGE2,
prostaglandin E2; PKA, protein kinase A; PKC, protein
kinase C; PLC, phospholipase C.
Adhesion complex/Integrin
Cytoskeleton
Protein
synthesis
Oxygen
tension
G-protein
Jun/Fos
Talin/Vinculin
cAMP/PKA
PLC
IP3
ras
DAG
PGE2
K+
Ca++
PKC
Extracellular
Cytosol
Intracellular
Ion channel
Cell membrane
Tyrosine kinase
Nucleus
Proliferation
MEKK/MEK
MAPK/JNK/P38
Mechanical stimulation

475
Basic science
Muscle
Muscle atrophies significantly during the process of expan-
sion, whether the prosthesis is placed above or below a specific
muscle. The effects on human muscle after expansion during
breast reconstruction have shown occasional histologic ulcer-
ation. Focal muscle fiber degeneration with glycogen deposi-
tion and mild interstitial fibrosis has been identified. In
addition, some muscle fibers show disorganization of the
myofibrils in the sarcomeres.24 Animal studies on the morpho-
logic changes in skeletal muscle suggest that the expansion of
skeletal muscle is not a stretching process but is rather a
growth process of the muscle cell accompanied by an increase
in the number of sarcomeres per fiber. Expanded skeletal
muscle returns to normal muscle architecture, vasculature,
and function after the prosthesis is removed.25 Moreover,
muscle mass returns to normal levels after removal of the
device in humans.
Bone
The effect of expansion on underlying cranial bone has been
studied in animal models. Decreases in both cranial bone
thickness and volume are evident beneath the expander
where bone resorption occurs. In contrast, there is an increase
in bony thickness predominantly at the expander periphery
where a periosteal inflammatory reaction is seen. Bone density
is unaffected.
Expansion over the cranium in children under one year of
age should be done judiciously. Depression of cranial bone
during expansion may occur before one year of age but
usually corrects itself once the expander is removed. In the
face of expansion, cranial bone appears to be measurably
more affected in thickness when compared to that of long
bone. Long bone remodeling begins within 5 days after
removal of the expander and the long bone is completely
normal within 2 months. Remodeling in cranial bone is com-
plete in 2–3 months.
Vascularity of expanded tissue
The robust vascularity of expanded tissue was clinically
evident long before laboratory work measured it (Fig. 25.3).
It has been clinically and histologically demonstrated that a
large number of new vessels are formed adjacent to the
capsule.26
The content of collagen fibers in existing vessels initially
decreases after expansion while elastic fibers in existing blood
vessels initially increase in response to mechanical stress.
Angiogenesis occurs in response to induced ischemia of the
expanded tissues. The number of cells expressing vascular
endothelial growth factor (VEGF) is significantly higher in
expanded tissue than in non-expanded, similar tissue.27
Expanded fascial flaps show a measurable increase in vascu-
larity between the fascia and subcutaneous tissue. Increased
perfusion to the distal and peripheral areas of the flap also
increases the robustness of the flap and the possibility of
harvesting a larger flap.26 Similar studies on prefabricated,
expanded, pedicled flaps have shown increased vascularity
within the pedicle, as well as in the adjacent random areas.28
The increase in vascularity affords the expanded tissue
important functional benefits. Animal studies have shown
that flaps elevated in expanded tissue have significantly
extracellular matrix remodeling for the deposition of granula-
tion tissue.18
Biology of tissue expansion
Extensive information is available regarding the biology of
tissue expansion. After the completion of animal experi-
ments,9,19 studies on human tissue examined the process of
tissue expansion that occurs both during the period of expan-
sion and postoperatively.20 Studies of the effects of tissue
expansion on nerve, muscle, and bone have also been
published.
Skin
Statistical analysis of multiple sites over the implant and its
periphery has revealed a significant increase in epidermal
thickness during the process of expansion and this thickening
occurs soon after expander placement. This is also seen in
sham controls and may represent, in part, postoperative
edema. Within 4–6 weeks, epidermal thickness generally
returns to initial levels, but some increase in thickness persists
for many months.
The increased area of skin over the expander includes not
only normal skin recruited from adjacent areas but also new
skin generated by increased cellular mitosis.21 Hair follicles
are not reproduced in humans, so individual follicles are
distracted during expansion. Distraction between follicles is
less noticeable in blondes than in dark-haired individuals.
Melanocytic activity is increased during expansion but returns
to normal levels within several months after completion of the
reconstruction. Although hair follicles and accessory skin
structures are compressed by tissue expansion devices, they
show no evidence of degeneration.
During expansion, the dermis decreases rapidly in thick-
ness over the entire implant. Thinning is most pronounced in
the first several weeks after implant placement and persists
for the entire period of expansion. Dermal thinning persists
at least 36 weeks after expansion is completed.22
Capsule
A dense fibrous capsule that becomes less cellular over time
develops around the implant. Progressive collagen deposition
occurs over 3 months with the development of well-organized
collagen bundles. Molecular studies have demonstrated
up-regulation of the wingless (Wnt) signaling pathway in the
pathogenesis of inflammation and capsule fibroproliferation
which may contribute to capsular contracture seen after radia-
tion therapy in breast cancer patients. Such increases have not
been demonstrated in non-irradiated tissue. This is further
supported by the growing body of evidence demonstrating
decreases in inflammatory markers and limited capsule for-
mation associated with the use of acellular dermal matrices
(ADMs).23 Although no evidence of dysplastic changes or loss
of normal cell maturation has been observed, dystrophic
capsular calcification may occur with repeated trauma to the
prosthesis or with hematoma resolution. After prosthetic
removal, the capsule resolves and little clinical or histologic
evidence of it remains over time. Histological examination of
capsular tissue demonstrates an extensive vascular plexus
within collagen such that capsule itself can be harvested as a
local flap because of this induced vascularity.

476
CHAPTER 25 • Principles and applications of tissue expansion
Fig. 25.4  Barium-injected radiograph of vessels in a random-pattern skin flap in a
pig (A) and an expanded flap in the same animal model (B). A dramatic increase in
the vascularity of the expanded flap is evident. (From Cherry GW, Austad E, Pasyk K,
et al. Increased survival and vascularity of random-pattern skin flaps elevated in
controlled, expanded skin. Plast Reconstr Surg. 1983;72:680–687.)
A
B
Fig. 25.3  Transillumination of expanded human skin demonstrating an intense
increase in arterioles and venules as well as a dense, interconnecting capillary bed.
The proliferation of capillary bed renders the overlying skin erythematous.
greater survival areas than acutely raised and delayed flaps
(Fig. 25.4).29 Similar studies employing labeled microspheres
have demonstrated an increase in flap survival, as well as
increased blood flow in the expanded tissue.
Diagnosis and patient presentation
The principles and technique of tissue expansion can be
applied in the management of myriad diagnoses with their
associated reconstructive dilemmas, therefore patient presen-
tation is variable. Examples of diagnoses where tissue expan-
sion may be utilized include, but are not limited to, traumatic
injuries and burns, male-pattern baldness and other forms of
alopecia, benign and malignant tumor extirpation defects,
breast deformities, and congenital or acquired craniofacial
deformities.
Patient and implant selection
Tissue expansion is a protracted procedure that may involve
temporary, but very obvious, cosmetic deformity. In general,
emotionally stable patients of all ages tolerate tissue expan-
sion well. Noncompliant or mentally impaired patients are
poor candidates for this technique. Although not an absolute
contraindication, tissue expansion in smokers is associated
with a higher risk of complications.30
Tissue expansion is generally best performed as a second-
ary reconstructive procedure rather than in the acute trauma

477
Patient and implant selection
Self-inflating expanders
Self-inflating expanders have become available largely outside
of the United States.31 These implants contain osmotic active
hydrogel (vinyl pyrrolidone) that causes migration of extra-
cellular water through the silicone membrane of the device
resulting in progressive enlargement of the expander. Another
type of self-inflating expander employs carbon dioxide for
filling. Through an internal carbon dioxide reservoir and
valve operated by a remote radio-control, small fixed amounts
of the gas are released into the expander resulting in progres-
sive enlargement.
The first such expander was devised by Drs. Austad and
Rose. The first generation of osmotic tissue expanders were
designed without an envelope allowing rapid swelling within
the first few days after implantation resulting in soft tissue
ischemia in some cases.9 Modifications of these implants to
include a silicone membrane which encloses the osmotic
tissue expander significantly decreased expansion speed and
improved size consistency after complete expansion.32 These
implants are currently not approved by the Food and Drug
Administration and are not available in the US.
Gas-filled self-inflating expander use in humans was ini-
tially reported in 2011 by Dr. Anthony Connell.33 Seven women
with 10 carbon dioxide expanders underwent successful
expansion. Subsequent to this proof-of-concept series, Dr.
Connell has demonstrated 100% expansion success rate with
only minor adverse events and high patient satisfaction.34
Self-expanding devices have the theoretical benefit of
continuous or patient-controlled inflation of the prosthesis.
Further benefits may include reducing the number of office
visits, decreased pain, no need for patient needle sticks, and
more rapid expansion. Such prostheses have the downside
of potential continued expansion even if overlying tissue
becomes compromised.
Incision planning and implant selection
The key to successful expansion is meticulous planning before
any incision is made. The proposed type of flap (advance-
ment, rotation, or interposition) that is to be expanded should
be carefully planned. In general: the simpler the flap, the less
the potential for complication. Ideally, planning is done so
that: (1) incisions are incorporated into tissue that will become
one margin of the flap; (2) aesthetic units are reconstructed;
(3) scars are in minimally conspicuous locations; and (4)
tension on suture lines is reduced. The length and position of
resultant scars play a major role in determining the overall
cosmetic postoperative result. Careful planning allows the
prosthesis to be placed through an incision that will both
minimize the risk of compromise during flap development
and optimize cosmetic reconstruction.
Incisions should be planned to minimize tension on the
suture line and risk of extrusion. Tension from the initial infla-
tion on the suture line will be greater when incisions are
parallel to the direction of expansion than when they are
perpendicular to it. Undermining of the prosthesis should be
sufficient enough that the prosthesis can be easily accommo-
dated and the wound can be closed in multiple layers. The
inflation valve and tubing should be maintained at a site away
from the incision.
Choice of an implant with an external distal port may affect
surgical planning. Cultures of implants with external valves
period. Expansion can be performed adjacent to an area of an
open wound before definitive closure, but such a procedure
carries the risks of infection, implant extrusion, and less-than-
optimal results. Tissue expansion is best suited to those
patients who require definitive, optimal coverage when time
is not of the essence.
Implant types
Radovan’s initial expander consisted of a silicone prosthesis
with two valves, each connected to the main reservoir by sili-
cone tubing.7 One valve was used to inject fluid while the
other was used to withdraw fluid. Technologic improvements
have allowed for the availability of a wide variety of off-the-
shelf and custom implants of any shape. These advances have
also decreased the incidence of mechanical failure associated
with earlier generation implants.
Advances in implant technology include the production of
a single valve that allows for fluid injection or removal as well
as integrated valves within the expander reservoir. Prostheses
that expand differentially into a specific shape, rather than the
usual round or rectangular configuration, are also available.
Differential expanders have found the most use in reconstruc-
tion of the breast, where ptosis and projection of the inferior-
most portions of the breast are desired. Low-profile implants
that accordion on themselves have been designed to eliminate
fold-flaw erosion early in the expansion process. Further
modifications of tissue expanders have been made to incor-
porate surface textures with the theoretical advantages of
better tissue adhesion producing decreased rates of implant
malposition and capsular contracture.
Expanders with distal ports
Remote filling ports have the advantage of minimizing the
risk of implant puncture during inflation. The distal, self-
sealing injection port and inflation reservoir are connected to
the prosthesis by a length of tubing. This allows the injection
port to be placed away from the expander pocket and is
advantageous when the overlying skin and soft tissues are
thin or when the pocket is too tight to hold an expander with
an integrated valve safely.
It is also possible to move the inflation port of a distant
reservoir to the exterior of the body. External location facili-
tates inflation, particularly when the expansion is accom-
plished by ancillary help or family. Concerns about colonization
risk can affect both selection of an implant and management
of complications.
Expanders with integrated ports
The inflation reservoir may be incorporated directly into the
prosthesis. Such devices have the advantage of avoiding the
remote port and its associated mechanical problems. However,
the risk of inadvertent perforation of the prosthesis during
inflation is higher with integrated valves because the valve
and integrated prosthesis can be difficult to palpate. Magnetic
and ultrasonic devices can be useful when the valve is difficult
to locate and metal-finding devices have been designed.
Expander prostheses with integrated valves are particularly
popular for breast reconstruction where adequate soft tissue
and implant pocket can accommodate the added projection of
the injection port.

478
CHAPTER 25 • Principles and applications of tissue expansion
Skin that has suffered a partial-thickness burn or that has
been scarred by adjacent burns is attenuated and is more
amenable to expansion.36 Incisions can be placed in previous
scars, but the scar should be mature and relatively thick so
that extrusion does not occur. Using an access incision within
normal tissue that is peripheral to the burned area further
minimizes the risk of extrusion. The principle of using mul-
tiple, smaller-volume prostheses is especially appropriate in
the burn patient. Perioperative antibiotics and meticulous
preparation are always used since the incidence of infection
is higher in burn patients.
Tissue expansion in children
Skin and soft tissue are always thinner in children than in
adults. These tissues are probably better vascularized but less
resistant to trauma. Tissue expansion has a higher complica-
tion rate in children than in adults. Rather than using exces-
sively large prostheses or expanding tissue aggressively,
accomplishing serial repeated expansions may be helpful in
children. This is done with the understanding that major
complication risk – particularly extrusion – is more common
at the second, third, and fourth serial expansion.37 This is
particularly true in the head and neck (with the exception of
the scalp). Expansion of the facial areas and neck can be
particularly difficult.
After age five, most children are able to adequately cooper-
ate therefore complication rates decrease. In many children,
an external reservoir is used to minimize the amount of
emotional trauma caused by injections. Application of EMLA
to the skin over the buried injection port is also helpful in
minimizing discomfort. Small volume inflation at frequent
intervals is especially useful in children because the amount
of pain generated is considerably less.
As in all cases, planning should be meticulous so that the
flaps generated will result as much as possible in reconstruc-
tion of anatomic units. With growth, contracture may occur,
particularly about the mouth and around the orbits, and revi-
sion will be required.
Expansion of myocutaneous, fascial, and
free flaps
Myocutaneous flaps are the standard of care for the treatment
of large defects, particularly when bone and vital structures
are involved. The territories of standard flaps are well
described. These territories can be considerably enlarged by
placing an expander beneath the standard myocutaneous
flap, and an extremely large flap can be developed over a
short period. Expansion increases the vascularity of the flap
and allows a large, adjacent random area to be carried with
the original flap.38 The vascular pedicle of such flaps remains
intact and may in fact be elongated, thus allowing flaps to be
transferred farther.
Myocutaneous flaps such as the latissimus dorsi and
pectoralis major can be expanded to almost double their surface
area, allowing coverage of almost any defect of the abdomen or
thorax.39 Expanders of up to 1000 mL can be placed beneath
such flaps and rapidly expanded. For example, bilateral latis-
simus dorsi myocutaneous flaps can be expanded and moved
to the midline to cover large meningoceles or the vertebral
column. In these cases, one edge of the myocutaneous flap is
selected for implant placement, and care is taken not to injure
revealed that 82% of these prostheses had colonized the
expander capsule and had some infection present which
constitutes an infection risk that is slightly higher than that of
totally buried prostheses.35 Although patients tolerate this
colonization well and experience few complications, external
ports are contraindicated when a permanent prosthesis or
bone grafts are to be used after expansion is complete.
The size of the implant selected should closely relate to the
size and shape of the donor surface. An implant equal to or
slightly smaller than the donor area is selected. Because there
is minimal risk in hyper-inflating the prosthesis to several
times the manufacturer’s designated volume, less importance
is placed on the implant’s specific volume than on its overall
base size. On occasion, a custom-fabricated implant may be
necessary.
In general, the use of multiple small expanders is better
than the use of one large expander. Inflation of multiple
prostheses proceeds more rapidly and complications are
fewer. Multiple expanders also allow the surgeon to vary the
plan for reconstruction after expansion has been achieved.
Because of the variety of functional, medical, and surgical
considerations, the choice between an integrated valve and a
distal inflation port should be considered on a case-by-case
basis, without neglecting plans for infection control and the
possible need for nonmedical personnel to inflate the implant.
Implant and distal port positioning
If a remote or distal filling port and reservoir is chosen, it must
be placed superficially in subcutaneous tissue, where even an
extremely small port is easily palpable under stable skin. To
minimize discomfort, it is occasionally possible to position a
filling port in an area that is relatively less sensitive. The port
should be placed in a location that will not be subjected to
pressure when the patient is lying in a position that could put
direct pressure immediately over the fill port. Bony promi-
nences are avoided if possible.
Care must be taken to avoid kinking of the tubing so that
the injected saline will flow readily to the prosthesis. The
prosthesis tubing should avoid the incision through which the
implant is placed and should not traverse joints. If placement
of an external valve is chosen, the connecting tubing should
be tunneled a significant distance from the prosthesis.
Tissue expanders are usually placed beneath the skin and
subcutaneous tissue above fascia. When the subcutaneous
tissue is thin or the risk of extrusion is significant, prostheses
may be placed under muscle.
Treatment and surgical technique
Burns
The use of tissue expansion in the reconstruction of burns,
particularly involving the scalp and face, has revolutionized
the treatment of burn patients. Because there is almost always
inadequate tissue after burns, reconstruction should be carried
out after all burns have thoroughly healed and scars have
matured. Planning is particularly important in these cases so
that a minimum number of suture lines are produced and that
these suture lines do not cross aesthetic units. Significant late
distortion and contracture may result in excessive scars placed
in burned tissue, particularly in the facial area.

479
Treatment and surgical technique
1. The scalp is unique in that it contains specific hair-
bearing qualities that cannot be mimicked by any other
tissue of the human body.
2. The forehead is a continuation of the scalp, but it is
distinguished from the scalp by its thick skin, large
number of sebaceous glands, and lack of hair.
3. The nose is embryologically related to the forehead, so it
closely mimics the forehead in color, texture, and
sebaceous gland content.
4. The lateral cheek areas, neck, and upper lip have fewer
sebaceous glands; the skin is thinner, and the hair-
bearing pattern is significantly different in quality and
quantity from that on the remainder of the body.
5. The skin of the periorbital areas is extremely thin and
pliable, containing a minimal number of sebaceous
glands.
There is a limited amount of tissue on the human face, so
procedures must be planned carefully and reconstruction
accomplished correctly at the first attempt. Correct planning
should take into consideration the area and shape of the defect,
quality of the remaining tissue of the aesthetic unit, pre-existing
scars, and reconstructive needs of other areas of the head and
neck. Because of the risk of complications, it is prudent to plan
alternative reconstructive strategies before any prostheses are
placed. If there is a chronic infection, the presence of fistulas,
or the need to reconstruct facial mass/volume, other recon-
structive alternatives may achieve a better final result.
Scalp
Tissue expansion is the ideal procedure for the reconstruction
of scalp defects (Fig. 25.5).42 Expansion of the scalp is well
tolerated and is the only procedure that allows development
of normal hair-bearing tissue to cover areas of alopecia. The
amount of scar and deformity generated is considerably less
than with previous procedures such as serial reduction and
complex multi-flap procedures. While some animal studies
have demonstrated an increase in hair follicles during tissue
expansion, our clinical experience suggests that humans do
not form a significant number of new follicles. Rather, existing
follicles are redistributed to a larger surface area. Because of
the finite number of follicles, attempts should be made to
redistribute them as homogeneously as possible. To accom-
plish this, large or multiple expanders, expanding large areas
of the remaining scalp, produce the best results. Hair follicles
can be separated by a factor of 2 without producing noticeable
thinning. The darker the hair, the more visible the thinning is.
Individuals who have large defects and require extreme
expansion may achieve better results by lightening the hair
color with dyes.
Although there is considerable overlap in the vascular
territories of the scalp, the incorporation of one or more major
vessels of the scalp optimizes reconstruction. Flaps should be
well vascularized to ensure maximum growth of hair. Plan-
ning is therefore of importance, as is consideration of scar and
previous areas of trauma. Advancement or rotation flaps
achieve the best results, particularly when the anterior hairline
is reconstructed. Simultaneous expansion and mobilization of
the forehead may also help achieve a normal hairline.
Previous scars and incisions can be used for placement of
the prosthesis. Once the galea is encountered, dissection can
proceed widely with a blunt dissector. It is not unusual to
the vascular pedicle. The expanded myocutaneous flap gener-
ated can then be transferred as either a pedicled flap or a free
flap. Such expanded flaps not only provide coverage of other
donor defects but also preserve the function of the muscle.
Fasciocutaneous flaps can be expanded either before or
after transposition. When flaps are expanded before transfer,
it is best to keep the prosthesis as far away from the pedicle
as possible, thus preferentially expanding the random area of
the flap. Within 6 months of transfer of these flaps, the random
blood supply is usually sufficiently established to allow place-
ment of the expander anywhere under the flap.40
Expanded full-thickness skin grafts
Because a donor defect is usually created by harvesting full-
thickness grafts, their use is infrequent. The placement of a
large tissue expander beneath the donor site can result in a
large full-thickness graft that is particularly useful in resurfac-
ing large areas of the face or the entire hand or foot. Expanded
full-thickness grafts are extremely resilient and have been
shown to grow in children over time. The rate of contracture
is significantly less than that of split-thickness grafts.
The best color matches are generated when the full-
thickness graft is expanded and harvested as close as possible
to the recipient site. The periorbital area and the area around
the mouth are particularly well suited to reconstruction with
expanded full-thickness grafts harvested from the supracla-
vicular area. Expanded full-thickness grafts are very helpful
in reconstructing defects of the forehead that encompass more
than 70% of its surface area. A single full-thickness graft can
be harvested from the supraclavicular area or from under the
breast fold. Care must be taken that hair-bearing tissue is not
transferred to an area that normally has no hair. Expanders
with a surface area equal to that of the donor site are placed
through peripheral incisions. The prosthesis is then inflated
to an adequate volume. After sufficient donor tissue is gener-
ated, a template is made of the recipient site and transferred
to the expanded donor area. The full-thickness graft is har-
vested so that it is approximately 10–15% larger than the
recipient area, allowing for some contracture. The prosthesis
is then removed, leaving the capsule intact, and the donor site
closed primarily. Closing of the donor site should be done so
that the resulting scar is as inconspicuous as possible. In the
recipient site, expanded full-thickness skin grafts require
more immobilization than do split-thickness skin grafts. A
bolster dressing or, ideally, a VAC sponge dressing is required.
The graft is sutured in place, a VAC sponge placed over the
graft, and 125 mmHg of negative pressure is maintained for
4 days. Successful take of such grafts placed with this tech-
nique is extremely high.
Reconstruction in the head and neck
The head and neck area contains many specialized tissues that
must be matched appropriately to achieve optimal aesthetic
reconstruction. Aesthetic reconstruction is maximized by
mobilization of adjacent local tissues rather than by transfer
of distant tissues with poor match of color, texture, or hair-
bearing capability. Tissue expansion therefore allows optimal
aesthetic reconstruction by use of a similar adjacent tissue area
to reconstruct a defect without creation of a donor site.11,41
The skin of the face can be subdivided into five tissue-
specific areas:

480
CHAPTER 25 • Principles and applications of tissue expansion
Fig. 25.5  (A) Young woman with avulsion injury to the right scalp, which had been
covered with a transposition flap from the left scalp that resulted in a scalp and
forehead skin graft. Two expanders were placed, one on either side, encompassing
as much of the hair and forehead as possible. (B) Expanders removed and
advancement flaps ready for repositioning. (C) Patient shown postoperatively with a
normal hairline, normal brow, and normal hair-bearing scalp.
A
B
C
mobilize most of the remaining scalp so that the prosthesis is
well accommodated. Individual pockets are not necessary for
multiple expanders, but care should be taken to fix the infla-
tion reservoirs so that they do not migrate into a common
pocket. Prostheses with incorporated inflation reservoirs can
also be used, but patients often find them bulky and uncom-
fortable. Inflation reservoirs can be placed at the vertex of the
scalp or in the forehead but care should be taken not to place
them where pressure is applied during sleep.
Expansion of the scalp is initially uncomfortable. It is better
to use frequent small saline injections than to use infrequent
large injections. After several weeks, the scalp loosens, and
large amounts of saline can be infused without difficulty. Most
scalp expansions can be accomplished in 6–8 weeks, particu-
larly when multiple expanders are used.43
Once adequate expansion has been achieved, the prosthe-
ses are removed through the incisions through which they
were originally placed or at the margin of the flap to be
moved. Flaps should be designed for advancement, transposi-
tion, or rotation. Every attempt should be made to minimize
transection of the major vessels of the scalp as this will allow
faster healing and better regeneration of hair follicles. Removal
or cutting of capsule and galea should be avoided in order to
preserve blood supply. Large areas of the scalp are mobilized
and positioned by temporary staples. Dog-ear deformities
created with flap inset are left in place because they subside
over time. The wounds are then closed.
It may be impossible to gain an adequate amount of tissue
with one expansion when large areas of the scalp must be
resurfaced, in which case serial expansion is used (Fig. 25.6).
After the initial expansion, flaps are advanced as far as pos-
sible. Lesions or areas of alopecia are excised only after the
flap has been advanced. The expander is then left in place
under the flap and, after several months, the scalp is
re-expanded. Adults tolerate three or four sequential expan-
sions without difficulty. The skin of infants and children may
thin excessively after two expansions and an interim period
of 8–12 months is optimal for a later expansion.
In growing children, scars frequently widen over time.
These require revision when they become a cosmetic problem,
optimally after 16–18 years of age. Scalp that has been vigor-
ously expanded may lose some hair follicles, but these usually
regrow hair. Twelve months should pass before any areas of
alopecia are considered permanent.
Some erosion and depression of the skull may be seen in
children radiographically and, occasionally, clinically. Expan-
sion should best be delayed in children until they are approxi-
mately 1 year of age. By this time, the skull is solid enough
that significant erosion is not a cause for concern. Long-term
studies have demonstrated no detrimental growth of the skull
in children who have undergone scalp expansion in infancy
(Fig. 25.7).
Male-pattern baldness
Tissue expansion can be used to develop hair-bearing flaps
that will replace skin that is affected by male-pattern bald-
ness.44,45 Expansion allows the homogeneous distribution of
the remaining hair follicles and reduces the tension that can
be caused by excision of scalp.
In patients with vertex baldness, the remaining temporal
and occipital scalp can be expanded for 2 months. Expanders

481
Treatment and surgical technique
Fig. 25.6  (A) Child born with a giant hairy nevus occupying one-third of the scalp. (B) The remaining normal scalp was expanded, allowing removal of more than half of the
lesion. (C) The original expander was left in place and 4 months later re-expanded, generating tissue that allowed removal of the remaining lesion. (D) The patient is shown 1
year after expansion. (E) The patient 10 years after expansion with stable hairline and normal hair distribution. (F) Patient shown at age 18. No revisions have been required.
A
B
C
D
E
F
of the scalp behind it. The bilateral advancement-transposition
flap is especially efficacious in transposing a large amount of
hair to the forehead.47
Forehead
The forehead is anatomically and histologically identical to the
scalp except for its different numbers of sebaceous glands and
hair-bearing follicles. Reduction or increase of the surface area
of the forehead by 20–25% is not usually readily apparent after
appropriate hair styling. By expanding the scalp in conjunction
with expanding the forehead, better symmetric brow position-
ing is achieved while maintaining the normal hairline.
In individuals with very high hairlines, the scalp can be
expanded posteriorly and brought forward to the junction of
the forehead and scalp. Generally, a lateral movement of scalp
tissue is less visible postoperatively. When defects involve
tissue lateral to the orbit, expansion of the cheek area with
cephalad movement of the exposed tissue may be helpful. The
temporal hairline and the lateral hairline that lies anterior to
the ear can be reconstructed with an advancement or trans-
position of a scalp flap.
are placed through incisions that would normally be used for
scalp reduction. Cosmetic deformity during this process may
be significant after the first several weeks. At the second
procedure, the scalp is advanced as far as possible and the
area of alopecia removed.
Patients who are unable to accept the deformity that occurs
with single large expansions can be serially expanded and
undergo serial scalp reduction. In these patients, the prosthesis
is inflated until deformities become visible. The expanders are
deflated and the hair-bearing flaps advanced as far cephalad as
possible. The prostheses are left in place, and a second or third
expansion is carried out until the entire bald area is removed.
Expansion can also be used to significantly increase the size
of standard transposition flaps used in the management of
male-pattern baldness. Anterior baldness that affects the
hairline can be modified into a new, natural-looking hairline
with Juri transposition flaps. However, these flaps are limited
in size and may require multiple delays to ensure adequate
hair viability.46 Expanders placed beneath the temporoparietal
area can dramatically increase the size of Juri flaps and
increase their safety. Bilateral flaps, one transposed behind the
other, will cover the entire forehead and a significant portion

482
CHAPTER 25 • Principles and applications of tissue expansion
D
E
F
G
H
Fig. 25.7  (A) An infant born with severe aplasia cutis congenita involving the scalp, skull, and derma that left exposed brain. (B) The brain was covered immediately after
birth with two, large, scalp–forehead advancement flaps. Absence of the cranium prevented the patient from attending school. (C) At age 4 years, the flaps were separated
from the underlying brain; a reinforced polyethylene sheet was secured to the cranial defect, an expander was placed over the sheet, and the scalp was expanded for 3
months. (D) The cranium was reconstructed with multiple split-rib grafts within the expanded capsule. (E) One year later, the scalp was re-expanded to more than 1000 mL
over the reconstructed cranium. The skin graft was excised and the scalp and forehead flaps were repositioned appropriately. The reconstructed skull suffered no ill effect
during the re-expansion. (F) Patient shown 1 year after reconstruction. (G) The patient at age 36 with an intact skull, normal scalp, and minor alopecia. (H) Posterior scalp
showing thinning of hair-bearing tissue, but a resilient, pliable scalp over an intact cranium. (From Argenta LC, Dingman RO. Total reconstruction of aplasia cutis congenita
involving scalp, skull, and dura. Plast Reconstr Surg. 1986;77:650–653.)
A
B
C

483
Treatment and surgical technique
expanded forehead to the underlying skull with small screws
reduces the amount of retraction.
If the entire forehead must be reconstructed, the optimal
choice is the use of an expanded full-thickness graft from the
neck. These grafts must be secured in place with negative-
pressure devices for at least 4 days.
Lateral face and neck
The type of skin on the lateral facial areas and neck is essen-
tially the same. This skin has hair-bearing potential and is
relatively thin, but contains numerous oil and sebaceous
glands. It is much thinner than skin on the forehead and nose.
A large Mustardé expanded rotation flap can be developed
on the neck for use in facial reconstruction. In children, there
is a higher risk of extrusion problems in the expansion of this
Prostheses are usually placed in the forehead through
an incision in the scalp. The prostheses are placed beneath the
frontalis muscle because this plane is safe and a well-vascu-
larized flap can be developed. Multiple expanders are usually
needed both to generate adequate tissue to be mobilized and
simultaneously to allow the brows to remain in an appropri-
ate symmetric position. Expansion is at first difficult and
uncomfortable, but as in the scalp, the expansion proceeds
rapidly after several weeks. Flaps may be developed in any
direction but are usually simple advancements. The adjacent
scalp should be mobilized at the same time so that a normal
hairline can be reconstructed.
Expansion of the forehead is useful in many craniofacial
anomalies with low hairlines. Expansion of the remaining
forehead is accomplished and moved in a cephalad direction.
The intervening hair-bearing scalp is excised. Fixation of the
Fig. 25.8  (A) An infant with a giant hairy
nevus of the face. (B) The neck and lateral
face were expanded by placing a prosthesis
through an incision in the nevus. An
expanded Mustardé cheek rotation flap was
rotated as an aesthetic unit over the lateral
face. (C) The patient at 5 years of age.
(D) The patient at 18 years of age with
minimal scars that are easily amenable to
makeup. (E) Lateral view demonstrating no
ectropion and an aesthetic reconstruction.
A
B
C
D
E

484
CHAPTER 25 • Principles and applications of tissue expansion
The lower half of the face and the neck are aesthetically
the same unit. Hair distribution, sebaceous gland density,
and skin thickness are similar. Defects of the lower face and
neck can be interchangeably reconstructed by expanding
either the lower face or the neck. Most frequently, the neck is
expanded and the flap advanced into the lower face. If nec-
essary, bone grafts that are placed beneath the expanded flap
can reconstruct the mandible and maxilla. The prosthesis
should be placed in the neck superficial to the platysma
muscle. Once an adequate amount of tissue is generated, the
flaps can be brought superiorly to cover the lower edge of
the face, medially to cover the central portion of the neck, or
laterally in the neck as needed (Fig. 25.9). In cases where
flaps are brought from the neck into the face, it is important
to secure the flap with permanent sutures to the deep
muscles at the commissures of the mouth. If this is not
accomplished, oral incontinence may develop later. Form-
fitting neck collars may be necessary to secure the expanded
flap in place over the neck after a portion of it has been
brought on to the face.
Nose
Reconstruction of major defects of the nose, including total
nasal reconstruction, may be facilitated by pre-expanding the
forehead skin. Before the use of tissue expansion, having both
area of the face (Fig. 25.8). In adults, such reconstruction can
be accomplished with relative ease. The flap is based inferiorly
and medially.
The prosthesis is inserted through a preauricular facelift-
type incision. The platysma should not be incorporated
because doing so exposes the marginal mandibular nerve to
trauma and restricts flap advancement. Distal reservoirs are
usually placed in the neck or behind the ear. The prosthesis is
then inflated as tolerated by the patient. Despite placement of
the prosthesis over the carotid artery and jugular vein, few
complications have been encountered. Once an adequate
amount of tissue has been generated, the Mustardé flap is
elevated. This is done through a preauricular incision that is
carried in front of the hair-bearing scalp and then on to the
lateral orbital area above the lateral canthus. The flap is then
rotated medially and superiorly to cover the areas of the cheek
that require resurfacing. In general, it is best to rotate this flap
and secure it in place with temporary staples before the recipi-
ent area is excised. It is best not to carry the medial scar in
this flap beyond the lateral commissure because scars below
that feature tend to distort the mouth. The flap is suspended
both medially and laterally at a level above the canthus which
minimizes the development of later ectropion. If coverage is
required for the periorbital area, this is done as a separate
aesthetic unit graft, usually a full-thickness graft from the
supraclavicular area.
Fig. 25.9  (A) Young man who sustained extensive
burns over the face, but in whom the neck was largely
spared. (B) Bilateral large expanders were placed in
the neck and the entire neck and upper chest were
expanded dramatically. (C) The area of burned skin
over the lower face was excised and the neck flap
advanced superiorly. The capsule was secured firmly
to the muscle on the lateral commissures to minimize
later distortion of the mouth. (D) The patient 2 years
later. The upper lip has been reconstructed as an
aesthetic unit from hair-bearing, temporoparietal flaps.
A
B
C
D

485
Treatment and surgical technique
Any of the standard forehead flaps can be employed in
conjunction with expansion. If reconstruction of the nasal
lining is also necessary, expansion of a forehead or Converse
scalping flap develops enough tissue to allow folding of the
expanded tissue on itself.
The supraorbital and supratrochlear vessels are located by
Doppler examination, and the nasal flap is based on the loca-
tion of either of these axial vessels. Prostheses are best placed
beneath the frontalis muscle through an incision above the
inadequate amounts of tissue and difficulty closing the fore-
head could be anticipated. However, now, when total nose
reconstruction is performed, expansion of the entire forehead
with a 400–600-mL prosthesis generates an adequate number
of large, well-vascularized flaps to accomplish both total nose
reconstruction and closure of the donor site. Because the color
and texture of the forehead are ideally suited to reconstruction
of the nose, this procedure makes reconstruction of any nasal
defect possible.
Fig. 25.10  (A) This woman had her nose resected for a mucosal melanoma. Three years later, reconstruction was begun by placement of a 450-mL expander in the
forehead. (B) At the second procedure, the infrastructure of the nose was made with a cantilever bone graft and bilateral, conchal cartilage grafts. (C) The forehead flap was
turned down in the subperiosteal plane to the level of the medial canthus. (D) The distal third of the flap was markedly thin so that the skin could be turned on itself to
recreate the nasal lining. (E, F) The patient 11 years after reconstruction with a functional breathing nose. No further modifications have been required in the succeeding 24
years.
A
B
C
D
E
F

486
CHAPTER 25 • Principles and applications of tissue expansion
A
B
C
D
E
Fig. 25.11  (A) A complex midface giant hairy nevus in a newborn. Reconstruction was undertaken in multiple stages at 2.5 years of age. (B) Bilateral expanders were
placed in the neck area to reconstruct the lateral face and a third expander was placed in the lateral thoracic wall to generate an expanded, full-thickness skin graft.
(C) Bilateral Mustardé cheek flaps were advanced as aesthetic units. Note that the nevus outside the anatomical aesthetic unit was left in place to be resected later.
(D, E) The forehead was excised and a full-thickness skin graft was harvested from the expanded right thoracic wall.
hairline. At the second procedure, the expander is removed
and the flap, including the capsule, is rotated inferiorly.
Approximately 2 cm above the supraorbital rim, the posterior
capsule is incised, and development of the flap is continued
in a subperiosteal plane. This allows further mobilization of
the flap into the orbit and dissection may continue almost
down to the canthus.
Having sufficient bony and cartilaginous supporting struc-
tures of the nose is critical to avoiding contraction of the
expanded tissue. Early experience in use of expanded fore-
head tissue was unsuccessful because the underlying bony
and cartilaginous structure was not adequate. A cranial bone
or rib graft is taken to reconstruct the dorsum of the nose. This
is either secured to the remaining nasal bone or attached by
a plate to the skull. The nasal cartilage is reconstructed bilater-
ally with cartilage from the conchal bowl. Thinly carved rib
cartilage is also useful if the ear cartilage is inadequate. Nasal
stents are used for 3–4 months to maintain a patent airway

487
Treatment and surgical technique
I
J
K
(F) The expander in the lateral thoracic area was left in place and re-expanded. In a later procedure, the remaining areas of nevus in the nasolabial folds
on each side were excised. The entire periocular and nasal area was then excised and grafted with full-thickness, expanded graft. (G, H) The patient 5 years after
reconstruction with a stable result. (I–K) The patient at 21 years of age. Note that the face has grown normally and symmetrically and that facial nerve function has been
maintained. The patient is able to hide remaining scars with minimal makeup.
Fig. 25.11, cont’d
G
H
F
while the flap matures. The forehead flap is divided and inset
approximately 2 weeks after rotation. Some swelling and
contracture of tissue may occur, but major touch-ups are
infrequently needed (Fig. 25.10).
Ear
Most cases of microtia and traumatic ear deformities can be
reconstructed without expansion. Expansion is helpful when
skin and soft tissue are insufficient for reconstruction. As with
all ear reconstructions, a child should be approximately 7
years of age before reconstruction is begun. A custom or
rectangular expander is placed beneath the remaining non-
hair bearing tissue that is adjacent to the ear remnant. The
prosthesis is then expanded and left in place for approximately
3 months. This allows both significant thinning of the overly-
ing skin and tissue maturity that will together result in
minimal secondary distortion due to contracture.48
The expander is best placed through an incision in the
postauricular hair-bearing tissue, preserving the temporopa-
rietal fascia for possible later needs. Once adequate tissue has
been generated, the framework is reconstructed with carved
costal cartilage. Some exaggeration of the bulk of the infra-
structure minimizes distortion because it conforms to the
cartilage. Silicone and other synthetic frameworks give excel-
lent initial results, but they are fraught with late complications.
In general, autologous tissues are recommended for ear
reconstruction.