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A
microvascular transplant, also known as
a free flap or free tissue transfer,
involves transplanting nonessential
donor tissue from one part of the body
to another to restore form or function.
The transplanted tissue must have
a single blood supply with an artery and
draining vein that are both adequate to
sustain circulation and life in the
transplant.
The free flap is anastomosed
(blood vessels connected) to recipient
vessels in or near the area to be
reconstructed and blood flow is
re-established.
A free flap is essentially an
auto-transplant.
Examples of some common free flap
procedures are presented in the links on
the left and in the home
page links. Some common types of
flaps are discussed on the flap
types page.
Free
flaps have multiple and widespread
indications such as:
-
Reconstruction
of complex wounds where compound
tissue loss has occurred
-
Tumor
ablation reconstruction
-
Reconstruction
of congenital deficiencies
-
Reconstruction
of chronic wounds
-
Reconstruction
after trauma
The
choice of donor tissue when planning a
free flap necessitates proper and
meticulous planning by the
reconstructive microsurgeon.
Factors that are considered include:
-
Size
and tissue type characteristics of
the area to be reconstructed - is
there a need for skin, muscle,
nerve, bone, fascia, tendon or any
combination of these? Does the
tissue need to be pliable or firm
and fixed? A breast
reconstruction requires soft tissue
with pliability and minimal
scarring. Wounds on the back
of the hand may require thin
tissues, with tendon or even bone.
Loss of the thumb is best
reconstructed with a great toe
transplant. On the other hand,
osteomyelitis of the tibia is best
treated by debridement and a muscle
transplant. Infected tissue is
often best treated with a muscle
transplant.
Muscles can also be used as
functional transplants, i.e. the
nerve is repaired and they are used
as a motor.
-
Location
of the area to be reconstructed -
breast, chest, arm, leg, head and
neck?
-
Pedicle
length required - are there blood
vessels nearby that the free flap
can be plugged into? The flap
must have blood vessels long enough
to reach an adequate artery and vein
in the recipient area.
-
Size
and type of donor tissue - what
flaps are the appropriate size and
tissue type for the area in
need? Is a flap with a nerve
required to reconstruct sensation?
-
Donor
site deformity - what flap is
expendable in this particular
patient? An athlete may
need to spare a muscle and would
instead opt for a fasciocutaneous
flap.
Flap
Terminology
Flap
terminology can be confusing, but an
understanding of the vocabulary aids in
the appreciation of the types of tissues
used and and the decision making in
microvascular transplantation.
Generally, microvascular transplants can
be divided into the following types of
flaps:
-
Skin
flaps
-
Fasciocutaneous
flaps - skin and fascia
-
Fascial
flaps
-
Muscle
flaps
-
Musculocutaneous
flaps - muscle and skin
-
Composite
tissue transplants - a combination
of tissues.
The
above diagram is a schematic
representation of a source artery and
adjacent anatomy that would lend itself
to tissue a tissue transplant. The
venous system has been left out for
clarity. A nerve might also run
beside or near the artery depending on
the flap. The main axial artery
can be dissected in combination with
different types of tissue. The
artery can be isolated with bone,
muscle, skin or fascia in numerous
combinations to construct a different
type of flap. Click on the
following thumbnails to see an
illustration of this concept to show how
four different types of flaps can be
created from the above theoretical donor
tissue area:
Skin Flap
Muscle flap
Musculotcuaneous flap
Osteomusculocutaneous flap
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