Basic plastic surgery techniques
and principles: Flap surgery
In the fifth part of our series,
Ben Taylor and Ardeshir Bayat
explain the finer points of
reconstructive flap surgery so
there is no need for you to get
yourself into a flap about it
Last month, we considered the lower rungs
of the reconstructive ladder.1 At times, however, the simple steps are not sufficient, and
the art of plastic surgery comes to the fore.
The plastic surgeon can move pieces of tissue, known as flaps, around the body to create a desired end result. Here we provide a
brief overview of the science behind flap
surgery.
The concept of flaps
A flap, like a skin graft, is an autotransplantation of tissue. The main difference
between the two, however, is that a flap
takes its original blood supply with it,
whereas a graft is completely stripped of its
blood supply during transfer. Because of
this, flaps can be made thicker, and can do a
lot more than skin grafts. Flaps are used
when a skin graft is unsuitable or would
leave the defect with inadequate bulk. Flaps
are more resistant to infection than grafts,2
Flap jargon explained
Primary defect—defect to be filled
Secondary defect—hole left by raising the flap
Pedicle—entry point of the blood supply to
the flap
Base—proximal part of the flap, which contains the pedicle
Tip—part of the flap furthest from the
pedicle
Tubing—when a flap “bridges,” or goes
from one point of the body to a distant
one, the middle bit is detached from
the body and is rolled into a tube to
minimise the risk of infection
Delay—raising the flap before transfer to
improve the blood supply
Transposition—lateral movement of a flap
into a primary defect
Rotation—rotation of a flap into a primary
defect
Advancement—moving a flap forward into
the primary defect
Pivot point—point around which a rotation
or transposition flap pivots
Local flap—flap which covers a nearby primary defect
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Distant flap—flap moving from one area to
an entirely different part of the body
Random pattern flap—flap without an identified source artery
Axial flap—flap based on a known source
artery
Peninsular flap—pedicle consisting of the
same layers as the rest of the flap
Island flap—pedicle consisting of only the
subcutaneous component
Free flap—vascular pedicle is divided; the
graft is removed and placed on a distant part of the body. Microsurgical
techniques are used to reattach (anastomose) the blood vessels
Angiosome—three dimensional block of tissue supplied by a single source artery
Choke vessels—small narrow anastomoses
between adjacent angiosomes
Skin flap—flap consisting of skin alone
Fasciocutaneous flap—skin flap and deep fascia
Myocutanoeus flap—skin flap and muscle
Osseomyocutanous flap—skin, muscle, and
bone
Muscle flap—Muscle alone
and they allow you to go back into the
wound for second stage repair. In addition,
microsurgical techniques allow the flap to
have some motor or sensory function, even
reanimation of a paralysed face.3
Flaps were used to repair noses as long
ago as 600 BC in India.4 But historically, flaps
have had their limitations, as Harold Gillies
wrote in 1957, “Plastic surgery is a constant
battle between blood supply and beauty.”5 In
the past 40 years, advances and rediscoveries
in understanding the viability of flaps and
their blood supply have given surgeons
more freedom.
Blood supply to the skin
In 1987, Ian Taylor published his work on
the blood supply to the skin and reintroduced the concept of an angiosome.6 An
angiosome is similar to the dermatome,
which you may learn about in anatomy.
Whereas a single nerve root supplies a dermatome, an angiosome is the three dimensional block of tissue supplied by a single
vascular system. If the source artery is
blocked, the angiosome can get some blood
from neighbouring angiosomes but to get
there the blood has to follow narrow calibre
tortuous anastomoses. An analogy is closure of a motorway leading to choking of
the small winding country roads with traffic.
Appropriately, these channels are known as
“choke vessels.” If a flap is raised, therefore,
without its source artery, the flap will rely
on choke vessels for its survival and may
fail. One way around this problem is to use
the “delay phenomenon.”7 The concept is
simple: you raise the flap but leave it for
one to three weeks allowing the choke vessels to dilate and perfuse the flap.
The arteries to the skin come from three
sources. They can perforate up from the
deeper tissues, either directly from a deep
artery or indirectly from a muscular artery.
Other channels of blood supply follow connective tissue planes such as deep fascia.
Finally, direct cutaneous arteries exist and
provide a good basis for a flap. Common
examples include the deltopectoral flap,
based on branches of the internal mammary
vessels, and the groin flap, based on the
superficial circumflex iliac vessels. These flaps
are known as axial pattern flaps, as they have
an artery running along their axis. Because of
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this they can be extremely long unlike a random flap, which is restricted in length.
Skin flaps
The simplest type of flap is a skin flap. As
the name suggests, it consists of only skin.
The size of such a flap is limited by the
angiosome concept, but the delay phenomenon can be used to help. Skin flaps are
usually used on the face, which has a good
blood supply. For more information on the
different types of skin flaps, see webextra
material on studentbmj.com.
Tissue expansion
One way of increasing the size of a local
skin flap is to use a mechanical device—a tissue expander—to stretch the tissue. These
expanders are usually silicone balloons that
are inflated periodically to stretch the tissues. After a long period of progressive
expansion, usually over a matter of weeks,
the excess tissue can be used as a local flap.
The procedure is useful in reconstructing
hair bearing areas, such as the scalp. However, the technique has its problems; a large
balloon under the skin looks very odd, and
the patient may not tolerate several weeks
of this. In addition, minor complications
such as scar widening and pain, as well as
serious complications such as haematoma,
infection, flap ischaemia, implant failure,
and the expander breaking out of the skin
may occur. Despite these problems,
expanders are widely used and usually
achieve excellent results.
Muscle flaps
It is not only skin which may be transferred
in a flap. Muscles are useful as they have a
good blood supply and the locations of the
vascular pedicles are well known.8 Muscles
are also versatile and can be used for providing bulk to the reconstruction when
desired. Owing to their good blood supply,
muscles provide a good surface for receiving a skin graft. Another way to get skin
cover is to use the skin and other tissues
overlying the muscles, as a myocutaneous
flap. This has other advantages in that more
skin can be taken, as the junction between
two angiosomes usually lies over a muscle.
Fasciocutaneous flaps
Sometimes the use of a myocutaneous flap
can leave a bulky appearance that is cosmetically undesirable. A layer of deep fascia
will allow you to take a large amount of tissue as a flap on the basis that blood vessels
follow connective tissue layers, and will not
have the same bulk as a myocutaneous flap.
Options for managing tissue defects using
the reconstructive ladder
This technique is especially useful and successful on the limbs.9
Distant flaps
In 1973, plastic surgery advanced further.10
A left iliofemoral flap was raised and then
the pedicle was divided to remove the flap
entirely from the body and leave it without
a blood supply. This briefly disembodied
flap was then used to fill a defect on the
right lower tibia, and microvascular techniques were used to suture the blood vessels into suitable recipient sites and
reperfuse the flap. Hence the free flap was
born. Today, free flaps allow the closure of
defects all over the body and grant the plastic surgeon a new degree of flexibility in
treating the patient.
Within a few years of the development of
free flaps, plastic surgeons discovered more
and more suitable donor sites and understood the factors relevant to success or failure. The skills and abilities during the
delicate microsurgical techniques required
improved with experience. Despite this, the
anastomoses are delicate and sometimes fail.
Conclusion
With all the tools available, a plastic surgeon can repair many defects and give the
patient a good, functional, and cosmetic
outcome. These techniques include an
increasing element of risk as you move up
the reconstructive ladder. Therefore, it is
always wise to start at the bottom and work
your way up, trying the simplest technique
that will work. (See figure left.)
Defect
Ben Taylor third year medical student
bentaylor@doctors.org.uk
Is the wound infected, or are there problems with the blood supply?
Yes
No
Attempt to treat the problem
Success
Can the wound edges be brought together without tension?
No
Yes
Failure
Depth?
Secondary
intention
healing
Skin
Primary
closure
Muscle
Bone
Size?
Large
Small
Will a skin graft
take on the wound?
Yes
Is a local flap
available?
No
Skin graft
Yes
Local flap
Healed wound
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No
Free flap
Ardeshir Bayat honorary lecturer and specialist
registrar in plastic and reconstructive surgery,
University of Manchester
ardeshir.bayat@man.ac.uk
1
Taylor B, Bayat A. Basic plastic surgery techniques and
principles: wound healing. studentBMJ 2002;11:271-3.
2 Mathes SJ, Alpert BS, Chang N. Use of the muscle flap
in chronic osteomyelitis: experimental and clinical
correlation. Plast Reconstr Surg 1982;69:815-29.
3 Mayou BJ, Watson JS, Harrison DH, Parry CB. Free
microvascular and microneural transfer of the extensor digitorum brevis muscle for the treatment of unilateral facial palsy. Br J Plast Surg 1981;34:362-7.
4 Wallace AF. The early development of pedicle flaps. J
R Soc Med 1978;71:834-8.
5 Gillies HD, Millard DR. The principles and art of plastic
surgery. Boston: Little and Brown, 1957.
6 Taylor GI, Palmer JH. The vascular territories (angiosomes) of the body: experimental study and clinical
applications. Br J Plast Surg 1987;40:113-41.
7 Callegari PR, Taylor GI, Caddy CM, Minabe T. An
anatomic review of the delay phenomenon: I. experimental studies. Plast Reconstr Surg 1992;89:397-407,
discussion 417-8.
8 Campbell J, Pennefather CM. An investigation into
the blood supply of muscles, with special reference to
war surgery. Lancet 1919:i;294-6
9 Cormack GC, Lamberty BG. A classification of fasciocutaneous flaps according to their patterns of vascularisation. Br J Plast Surg 1984;37:80-7.
10 Daniel RK, Taylor GI. Distant transfer of an island flap
by microvascular anastomoses: a clinical technique.
Plast Reconstr Surg 1973;52:111-7.
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