Flaps
More complex defects and avascular defects require flap cover. Flaps can
consist of skin only, or be complex composites of skin, muscle, bone or other
tissues. As their complexity increases so do their power and ability to
reconstruct more complex defects. Flaps can be classified according to the
geometry of their transfer such as rotation, advancement or transposition. A
more useful classification is provided by their vascular basis. The vascular
supply of a flap is known as its vascular pedicle; some flaps have more than one
vascular pedicle. The term pedicle is also used to describe the base or
attachment of a flap, which may also contain skin and other tissues as well as
the vascular pedicle. Where the skin is divided all the way around a flap it is
called an island flap.
2Flaps
from the cheek and forehead were used in India as early as 1000 ec for nasal
reconstruction. Tagliacozzi in 1597 published his method using flaps from the
arm. Multitudes of flaps were utilised in the nineteenth century. Tansini in
1896 described the latissimus dorsi flap for breast reconstruction. The
significance of the vascular basis of these flaps was not appreciated during the
development of modern plastic surgery after World War land World War II.
The
development of flap surgery
Flaps have been used since ancient times, often to repair complex
defects2. In the first half of the twentieth century, however, the
only flaps that were considered possible were skin flaps consisting of
rectangular portions of skin and subcutaneous tissue with length to breath ratio
of 2 to 1.5:1. Such flaps were of limited arc of transfer and their use to
reconstruct distant defects involved multistage surgery. Bipedicled flaps were
tubed to form tubed pedicle flaps that were attached to an arm carrier and then
transferred in several stages using multiple delays to a recipient site. It was
possible to perform complex reconstructions using these methods, but each stage
risked vascular compromise and flap loss, and donor site scarring was
considerable. This all took a long time and such flaps, when the transfer was
completed, depended on the local vascularity of the recipient site and did not
bring in an independent blood supply of their own. Modern flap practice has
developed since the discovery of the vascular anatomy of potential flap
territories and the vascular patterns of skin blood supply.
Random
pattern flaps
The vascular basis of random pattern flaps is the subdermal plexus of
blood vessels. These flaps are widely used for local repair of adjacent defects,
particularly on the face. Many geometric designs are possible. A particularly
useful pattern is a rhomboid flap (Fig. 13.4a—d). The Z-plasty is a local flap
technique that can be employed in a variety of situations, in particular
treatment of contractures and scar revision. A Zplasty or a combination of Z-plasties
can lengthen a contracture, change the direction of a scar, alter tension,
reposition specialised structures and improve the appearance of a scar (Fig. 13.5). It involves the transposition of triangular flaps. The maximum
lengthening is achieved by using 600 angles of flap design. Lengthening depends
on laxity at right angles to the contracture since it occurs at the expense of
shortening in a perpendicular direction.
Skin flaps with a known direct superficial vascular pedicle passing
along their long axis are known as axial pattern flaps. These defy previously
accepted length-to-breadth ratios that applied to random pattern flaps and
thereby long flaps can reliably be designed with longer axes of rotation3.
The forehead flap, the deltopectoral flap and groin flap all share this vascular
pattern.
FasciocutaneoUS
flaps
In many parts of the body blood vessels pass along the deep fascia or,
in association with intermusdular septae, pass perforating vessels to supply the
overlying skin. These flaps are raised along with the vascular pedicle by
dissecting along the relevant fascial plane. Long vascular pedicles can be
created, often with quite large vessels at their base. Fasciocutaneous flaps can
be transferred loco-regionally, or the vascular pedicle divided, the flap
transferred to a distant site and the flap revascularised by microsurgical
anastomosis to recipient vessels adjacent to the defect. This technique of free
tissue transfer has further extended the versatility of flap reconstruction.
Fasciocutaneous flaps can be skin only or can include associated tissue to
provide vascularised bone or
Muscle
and musculocutaneous flaps
Muscles have predictable patterns of vascular anatomy that permit the
elevation of a muscle on one or more of its vascular pedicles for use as a
muscle flap, either locally or as a free tissue transfer. Many muscles also have
perforating vessels passing from their substance into the overlying skin
enabling musculocutaneous flaps to be designed. Musculocutaneous flaps based
on the latissimus dorsi and rectus abdominis muscles are particularly useful in
breast reconstruction (Fig. 13.7a and b). These same muscles are widely used as
free muscle flaps to repair defects in the lower limb associated with open
tibial fractures (Fig. 13.8a—c). Gluteus maximus and tensor fascia lata flaps
are used for pressure-sore closure. Muscle flaps can be used as functional
transfers where their nerve supply is left intact or reestablished at the
recipient site. Such techniques are applied