FREE TISSUE TRANSFER

The treatment goal for the chronic wound is to treat the wound as a tumor and excise it in its entirety to the level of

normal tissue planes (Fig. 35.1; see also COLOR FIG. 35.1).
Excise all scar tissue. Bone debridement can be difficult, because it
can be challenging to distinguish the viable bone and healthy callus
from necrotic and inflamed areas. Techniques such as computed
tomography (CT) scans, bone scans, and magnetic resonance imaging (MRI)
may be helpful in preoperative planning for bone debridement.

At the conclusion of wound debridement, normal tissue
planes should be visualized. If this is not possible, then a
second-look procedure in which the debridement process is repeated is
strongly advised. Re-debride no later than 48 hours, and preferably at
24 hours after the initial debridement (65).

To understand the role of free tissue transfer in
orthopaedic surgery, one must understand the concept of the
“reconstructive ladder” (Fig. 35.2). It
represents an increasingly complex solution for soft-tissue problems,
with the ultimate goal being reconstitution of the soft-tissue
envelope. The reconstructive algorithm, or ladder, is used to select
treatment for damaged soft tissues. This algorithm should be used in
the setting of acute or chronic soft tissue injury, with or without
fractures. In addition, it can be applied to chronic conditions such as
osteomyelitis, nonunion, or tumors (63).

Coverage can be in the form of a skin graft, local
tissue transfer, adjacent tissue transfer, regional tissue transfer, or
free tissue transfer, which represents the most complex rung on the
reconstructive ladder and is the subject of this chapter. As
microvascular success rates have improved over the last three decades,
the certainty in which tissue can be transplanted to provide coverage
as well as function has been enhanced to an expected success rate of
more than 95%. Free flaps facilitate solutions to complex soft-tissue
problems, with the ultimate goal being reconstitution of the
soft-tissue envelope.

Debridement is the first step in the process of the
reconstructive ladder. After adequate debridement, it may be possible,
such as in minor hand injuries, to close a wound primarily. This is
known as primary closure (the first rung). This is rarely done in the
treatment of open fractures because of associated soft-tissue loss, the
degree of contamination, or the possible uncertainty as to the adequacy
of debridement.

Delayed primary closure (the second rung) can be
considered for reasons such as returning to the operating room in 24 to
48 hours after edema subsides, or if there is uncertainty about the
safety of the wound closure (gunshot wounds or farmyard injuries). A
wound may be left open to heal by epithelialization and wound
contraction, as in the so-called secondary intention healing. This is
the third rung of the reconstructive ladder. This may be applied to
small donor areas, such as for skin grafts, or in abrasions over muscle
compartments that have small areas that can rapidly epithelialize,
obviating the need for skin grafts.

The next rung on the reconstructive ladder is the use

of split or full-thickness skin grafts, either meshed or unmeshed. Skin
grafting successfully closes many wounds in the extremities,
particularly those that are beyond primary or delayed primary closure.
The wound bed must be well vascularized with a smooth pink bed of
granulation tissue for the graft to take. Grafts will work on fat,
muscle fascia, and even intact periosteum. It is important that wound
beds be cleaned before grafting to avoid flap loss by infection.
Immobilization of the graft is crucial for a good “take of the graft.”

More complex wounds—for example, those that contain
exposed vital structures such as nerves and arteries, bone that is
devoid of periosteum, or those that have insufficient vascularity and
soft tissue to support skin grafts—require the importation of
well-vascularized tissue to achieve wound closure. This may be
accomplished by either local or distant flaps, which are the next rungs
of the reconstructive ladder.

Rotational flaps, such as muscle, skin, fascia, or a
combination of these types, can provide much-needed vascularized tissue
and allow dead space to be obliterated and the wound to be closed
without tension. These options may be limited because of the wound
location or regional donor site deficiencies. In this instance, free
tissue transplantation must be considered.

The highest rung on the reconstructive ladder uses free
tissue transfer, possibly in combination with lower rungs of the
ladder, such as skin closure, skin grafting, or rotational flaps. An
example would be the use of a soleus myoplasty in the middle third of
the tibia as well as requirements

for distal third of the coverage. A muscle free flap, such as the latissimus dorsi, could be considered in such a case.

The reconstructive ladder has many rungs. The
reconstructive surgeon may go from one level to another and, in many
instances, may simultaneously use techniques from different levels of
the ladder for different problems. Familiarity with options on the
reconstructive ladder will help the reconstructive surgeon plan limb
salvage and avoid the adverse sequelae that results from improper
soft-tissue handling.

One of the main advantages of free flaps for hand
reconstruction is that they allow early mobilization of the hand
following injury. This feature decreases limb edema and postoperative
stiffness. Free flaps allow the possibility of composite tissue
reconstruction in one stage by transferring various combinations of
nerve, bone, tendon, skin, and muscle at once. Free flaps can be
contoured and cut to fit any defect precisely. Most important,
microvascular free tissue transfers have enabled us to adhere more
closely to one of the basic principles of any reconstruction effort, as
set forth by Gillies—“replace losses in kind”—by allowing us to
reconstruct these defects with tissue that is most similar to the lost
tissue.

Patients who undergo mutilating upper extremity trauma often have the greatest need for free tissue transfers (Fig. 35.3; see also COLOR FIG. 35.3A).
Trauma to the hand requires resurfacing using skin, muscle, or free
fascial flaps. In the treatment of upper extremity trauma, patients who
cannot be treated by conventional techniques such as skin grafting,
local flaps, or distant flaps are candidates for free tissue transfer.
When possible, it is desirable to import tissue rather than to use
island pedicle flaps, which will further compromise upper extremity
vascularity. For example, the radial forearm flap, if used for dorsal
hand coverage, renders an already compromised limb more compromised.
This method requires sacrifice of the radial artery. A fibula
osteoseptocutaneous flap can also be used in cases of trauma of the
upper extremity (Fig. 35.4; see also COLOR FIG. 35.4C).

Upper extremity tumors that involve compartment
resections are best treated with free tissue transfer; specifically
free muscle, skin, and free bone flaps (Fig. 35.5; see also COLOR FIG. 35.5B).

Upper extremity sepsis includes bone infection involving
large intercalary segments either in the humerus or the forearm. The
vascularized fibula transplant is an excellent method for
reconstruction of such defects. Soft-tissue sepsis can usually be
controlled and treated with local debridement and grafts, unless there
is massive necrosis requiring coverage, in which case select a free
skin or muscle flap selected.

A large selection of free tissue transfers for hand
reconstruction is available. One of the most commonly used flaps in
hand reconstruction is the lateral arm flap; this is a fasciocutaneous
flap that is a good choice for coverage of the dorsal or palmar
defects. It is thin, easy to dissect, and associated with few
complications (52).

Hand wounds resulting in palmar or dorsal defects can
also be covered with a free temporoparietal fascia flap. This flap has
a very low morbidity and a small scar because no skin is taken with the
fascia. The flap can be taken as a double-layered flap, incorporating
both the superficial and deep temporoparietal fascia on the superficial
temporal vessels (47). The dorsalis pedis flap,
scapular, parascapular, groin, and lateral thigh flaps can be used to
cover defects on the palm and dorsum of the hand (14).

Perhaps the best example of composite tissue
transplantation is toe transplantation. Toe transfers include vascular,
neural, osseous, tendinous, and nail components as part of the
composite.

Microvascular toe transplants are believed to be
superior to fingers or thumbs reconstructed by other techniques because
the toe includes a sensate pulp with nail support, a near-normal
appearance, and an active flexion mechanism of the transplanted toe (Fig. 35.6).

Both the great and the second toe have roles in
toe-to-hand transplantation. Each transplant has advantages and
disadvantages. The decision of which toe to transfer is based on
several considerations: the patient’s desire, donor morbidity,
aesthetic aspects, as well as the part of the hand where the toe is
needed. The patient should be informed that the donor morbidity from a
great toe harvest (from a cosmetic and functional standpoint) would be
greater than that of removing the second toe.

In a mutilated hand, where only a thumb is present,
there is a need for an opposable post at the fourth and fifth digit so
that the thumb and post can oppose each other. In such a case, it is
more appropriate to take the second toe; bilateral second-toe
transfers, or double-toe transfers, rather than the great toe (Fig. 35.7).

Thumb reconstruction by great-toe transplantation can be
considered if at least one third of the proximal portion of the first
metacarpal bone is present.

Second toe—to—thumb transplantation is indicated when a
large discrepancy in size exists between the great toe and the thumb,
when the loss of the great toe is not acceptable, or when the level of
amputation is proximal

to
the proximal third of the first metacarpal and a considerable length of
the metacarpal is necessary to provide adequate length. Second-toe or
multiple-toe transfers also are indicated in a hand from which all
fingers have been lost and there is no ulnar post against which the
thumb can oppose. In this situation, two second-toe transfers may
enhance the grip strength and the ability to manipulate fine objects.
Partial toe transfer of the second toe can be used for reconstruction
in cases of the amputation of a finger at the level of the distal
interphalangeal (DIP) joint or even the nail itself. The distal aspect
of the second toe can provide, in these cases, a pulp, sensibility,
nail plate, and osseous length, which eases the patient’s
self-consciousness (15).

Microvascular reconstruction of the distal digits by
partial toe transfer includes pulp flaps, which are used for volar
thumb and finger resurfacing. There are three major indications for
pulp transfer: (1) acute loss of the digital pulp, (2) unstable skin resulting from previous pulp reconstruction with skin graft or local flap, and (3) posttraumatic distal insensibility with pulp atrophy and distal neuroma with no possibility of nerve anastomosis (35).

If nail transfer is done, it should be based on at least
one artery through one hemipulp and venous drainage through the dorsal
skin proximal to the nail. A careful history as to whether there has
been any damage to the foot in the lifetime of the patient will
eliminate the need for an arteriogram. Doppler imaging can trace the
pathway of the dorsalis pedis artery in cases in which the artery
location needs to be found (32,67).

Peripheral nerve repair and brachial plexus
reconstruction following injuries have evolved parallel to the
development of microsurgery. In many cases of peripheral nerve injury,
primary repair may not be possible for many reasons, including direct
loss of nerve tissue from trauma, retraction of nerve stumps following
delay in repair, or resection of the nerve for a primary nerve tumor or
surrounding malignancies. Repair of the gap by primary closure with
tension is avoided because tension hinders regeneration by encouraging
gapping at the repair site with subsequent scar adhesion formation, as
well as reducing blood flow in the repaired nerve (27).
Nerve allografting is possible now owing to the advances in
immunosupression, although clinical application of peripheral nerve
allografting remains under experimental investigation (112).

Different procedures using microsurgical techniques have
been described for brachial plexus reconstruction. Some of these
techniques include nerve crossing procedures, free muscle transfer, and
more recently, a combined technique of double free muscle and multiple
nerve transfers. This procedure involves transferring the first free

muscle
neurotized by the spinal accessory nerve for elbow flexion and finger
flexion, a second free muscle transfer reinnervated by the fifth and
sixth intercostal nerves for finger flexion, and neurotization of the
triceps brachi muscle via its motor nerve by the third and fourth
intercostal motor nerves to extend and stabilize the elbow. Restoration
of hand stability is obtained through the suturing of the sensory rami
from the intercostal nerves to the median nerve (30).
The transferred muscles include latissimus dorsi, rectus abdominis, and
gracilis. The gracilis muscle is considered to be the best option by
many surgeons.

The orthopaedic surgeon, in particular the hand surgeon,
may encounter pathology that requires the understanding of free tissue
transfer techniques. These transfers are not the classic transfers used
in daily orthopaedic practice; thus, the subject will be mentioned
briefly.

Despite advances in limb reconstruction in the last
several years, resurfacing of the foot remains one of the most
difficult reconstructive problems. Not only is it necessary to
reestablish soft-tissue integrity but also the treatment plan must
include attention to bony architecture and foot deformities that can be
caused by muscle imbalance. Each anatomic region of the foot has
certain characteristics that will influence selection of the free
tissue transfer for reconstruction. The dorsum of the foot and the
ankle require thin pliable soft-tissue coverage for exposed tendons
that are devoid of paratenon, bones, or joints. The weight-bearing
surface of the foot (the plantar skin) is unique with respect to its
dermoepidermal histologic characteristics, the unique subcutaneous
tissue in the heel pad, adherent dermal septae to the underlying
plantar fascia, and the ability to withstand constant pressure and
shear forces.

Providing coverage along with protective sensibility can
be achieved with a free neurosensory flap such as the radial forearm
flap (22). Free muscle flaps are used when bulk
is necessary to obliterate dead space such as in osteomyelitis, severe
crush injuries with extensive soft-tissue loss, and for weight-bearing
surfaces (84). However, muscle flaps can often be bulky and, if they are not contoured properly, may prevent the use of normal shoes.

The radial forearm flap offers several potential
advantages over other fasciocutaneous flaps and muscle flaps for
resurfacing the foot and ankle. It meets most of the prerequisites for
the “ideal” foot flap: It provides a large amount of well-vascularized,
thin, and pliable soft tissue; it is easy to harvest; and it has large
consistent vessels and a long pedicle. Furthermore, it facilitates the
restoration of normal (original) foot contour by replacing
“like-with-like,” allowing patients to wear normal shoes, and can
provide a durable and stable weight-bearing plantar surface for
walking. It also achieves an excellent aesthetic result without the
need for debulking. Dryness and cracking of a hypertrophied skin graft,
especially at the flap–foot skin interface, is less of a problem with
skin flaps compared with free muscle flaps covered with split-thickness
skin grafts. In addition, it has the potential for sensory
reinnervation. Possible disadvantages include an unsightly donor site
scar, especially in a young woman, and donor site skin graft breakdown
with flexor tendon exposure.

The plantar skin has unique properties. It is thick and
heavily keratinized, designed to resist high stress, and it is anchored
to underlying bones and ligaments by thick fibrous connective tissue.
The plantar surface acts as a shock-absorbing system for the foot,
helping to minimize horizontal and vertical shear forces by its
multidirectional fibrous septae (115). The plantar surface of the foot can be divided into three distinct areas, each with special requirements for replacement.

The instep skin in the normal foot is not subject to
high stress and, in many cases, it has been used as a donor tissue for
plantar resurfacing. Forefoot skin is the subject of significant forces
during running and toe off in the normal gait cycle.

Base the decision to proceed with foot salvage on
whether the foot will function better than a prosthesis after the
reconstruction is complete. Achieving a normal gait cycle is possible
only if the foot can fit into a regular or slightly modified shoe, is
pain free, and ideally has some sensibility. Neurosensory flaps such as
dorsalis pedis, lateral arm flap, tensor fascia lata flap, and radial
forearm flap may be used to provide sensibility, but they may lack the
bulk and thickness required for cavitary tissue defects. Larger flaps
such as muscle flaps that do contour better cannot be innervated. Thus,
there is no ideal transfer. A review of flap options should be done for
each patient. The specific complications include wound breakdown
because of mechanical instability and excessive sheer forces,
ulceration, formation of calluses, hyperthrophic scarring, and
intrinsic muscle imbalance (62).

Nonhealing wounds of the extremities are common in
patients with diabetes and peripheral vascular disease. The magnitude
of the problem is enormous; statistics indicate that 14% of these
patients are hospitalized an average of 6 weeks per year for foot
problems, and more than 80% of amputations are performed on diabetics.
The contralateral limb of one with an ulcer is at risk for further
ulceration, and there is a 50% chance of loss of the opposite leg
within 5 years (43). Care of these patients
requires a close collaborative effort between the orthopaedist, the
peripheral vascular surgical team, and the microsurgical team to
optimize rapid and accurate assessment of the vascular problem, and to
determine the most appropriate and timely plan for wound care and the
most reliable method for revascularization. The results of
macrovascular and microvascular anastomoses are comparable to those for
nondiabetic patients undergoing the same procedure (58). Patients treated with cutaneous free flaps have less morbidity than patients treated with muscle free flaps (89).
The radial forearm free flap is ideal for treatment of relatively small
wounds of the foot and ankle. It provides cutaneous tissue with a
lengthy vascular pedicle and a donor site that can often be closed
primarily.

Despite the multiple medical problems of diabetic and
dysvascular patients, surgical mortality has not been found to be
higher in cases of microsurgical reconstruction procedures performed
alone in these patients or in combination with macrovascular vascular
reconstruction (13). Once the extremity has
been revascularized, the most appropriate method of reconstruction can
be carried out for defects of the foot in a well-vascularized limb. For
those patients in whom the macrovascular blood supply is intact and
without apparent compromise but who have large, unhealthy, colonized
wounds, particularly if they involve tendon or bone, free flap coverage
is indicated. Free tissue transfer techniques are ideal in these
situations because (1) they are able to resurface any size defect; (2) they allow aggressive resection of the wound to eliminate colonized, fibrotic, unhealthy tissue; (3) the flap can help revascularize the foot; and (4) the defect is replaced with healthy nondamaged tissue (Fig. 35-13; see also COLOR FIG. 35.13A, COLOR FIG. 35.13B).

Diabetic and dysvascular patients require a high degree
of vigilance to avoid problems both locally and systemically, with a
much closer observation of the donor sites and recipient sites to
preclude wound healing problems.

Because many diabetic and dysvascular patients are
candidates for amputation before flap transfer (which was often offered
as a last option before limb loss), these procedures do not increase
the rate of limb loss, but can only increase the limb salvage rate (Fig 35-14; see also COLOR FIG. 35.14A).
It is important to examine the result of lower extremity limb salvage
as it relates to ambulatory function. Salvage of a useless limb in such
patients is of little value in their overall management. Likewise,
heroic attempts at salvaging a limb are not indicated if the operation
subjects a patient to excessive morbidity.

The question of the cost/benefit ratio of such
procedures has yet to be determined. Certainly in this era of
cost-containment, the arguments against such “expensive” and
sophisticated procedures versus straightforward amputation cannot be
ignored. Although the exact cost of leg salvage in such a group of
patients is difficult to determine, it may be less expensive than the
combined cost of hospitalization, prosthesis fitting, rehabilitation,
and disability payments.

A high degree of success can be achieved only by
extremely careful patient selection. In the face of systemic
complications, one must also exercise proper judgment and abort
attempted reconstruction to ensure patient survival.

Chronic venous ulcers can also be treated with
microsurgical tissue transfers. In the appropriate patient with
localized disease, a dual surgical approach including wide excision of
the ulcer and surrounding liposclerotic tissue bed, and coverage with a
free flap containing multiple competent microvenous valves, may improve
the underlying pathophysiology. In patients with complex ischemic or
infected wounds from diabetes, free tissue transfer as an adjunct to
lower extremity vascular reconstruction can help in obtaining a
salvageable functional limb, thus presenting a viable alternative to
amputation (41,75).

Despite the success achieved in limb-salvage procedures,
a high number of amputations are performed as a result of major trauma,
tumors, diabetic ulcers, and in cases when the patient is too ill to
survive a lengthy operation. The level of amputation itself is an
important factor for consideration. In cases of lower limb amputation,
below-knee amputation is associated with faster rehabilitation compared
with above-knee amputation. Below-knee amputees require less
rehabilitation time, have a more natural gait, and can engage in more
physical activities (6). The choice for the
level of amputation is determined by the need to cover the stump with
appropriate soft tissue stable enough to resist breakdown in a
prosthesis. Skin grafting of amputation stumps, especially in lower
limbs, provides only wound coverage, and usually does not meet the need
for adequate padding. In cases for which a local flap is not available,
free flaps should be considered. These flaps can provide coverage of
the stump, and if microneural coaptation is performed, sensation of the
stump can be achieved. That may assist proprioception within the
prosthesis. An amputated limb may provide donor tissue, such as in
traumatic below-knee amputations (Fig. 35.15).

A free flap harvested from an amputated lower leg eliminates

donor site morbidity (114). Fillet foot flaps are useful for salvage of below-knee level amputees.

Free flaps can be categorized into two different types.
Isolated tissue transplants include muscle, skin, fascia, bone, or
flaps. The more common composite tissue transplant is a more complex
flap that provides more than one function. Examples include
myocutaneous, osteocutaneous, or innervated myocutaneous flaps.

The type of tissue deficiency and surface requirements
will determine the type of flap to be selected. Tissue transplants are
selected with respect to donor site morbidity, recipient site
requirements, vascular pedicle length, and anticipated aesthetic
result. For example, a myocutaneous latissimus dorsi flap should not be
transplanted to the dorsum of the foot due to its bulk and the fact
that the donor tissue does not match the dorsum of the foot. Other
flaps, such as an isolated skin flap (radial forearm flap or lateral
arm flap), are a better transplant. Similarly, to fill dead space after
sequestrectomy of an infected tibia, a lateral arm flap, which is a
small skin flap of approximately 5 × 7 cm is not appropriate owing to
its lack of bulk and the fact that the muscle flaps, rather than skin
flaps, are known to be more effective in the treatment of
osteomyelitis. The use of a skin paddle with composite tissue transfers
can be done for either contouring or as a monitor for perfusion of the
flap.

The next consideration is whether dead space needs to be
filled. If a flap were used purely for resurfacing, such as on the
dorsum of the hand, so that secondary tendon reconstruction can be
performed, a large bulky flap would not be required. However, if there
is significant dead space, a large muscle flap such as a latissimus
dorsi flap should be considered. Osseous flaps are selected for
structural defects such as intercalary bone defects resulting from
trauma, tumor, or infection. If a vascularized bone flap is to be
selected, the cross section of the bone defect, available vascular
supply, and fixation of the vascularized bone graft must be taken into
consideration.

Not all flaps are selected to replace missing tissue.
There are instances in which tissue coverage exists but it is
insufficient in texture or quality. A soft-tissue envelope may need to
be augmented, such as using a scapular flap to resurface a knee with
unstable skin as a first stage before a total knee replacement. There
are free flaps that are performed for purely aesthetic reasons, such as
the resurfacing of extremities. This is an unusual use of free tissue
transfer, and it is used only in special cases. A combination of the
above-mentioned selection factors determines free flap selection.

Specific preoperative assessment in microsurgical
procedures frequently includes angiography to evaluate the vasculature
of the recipient site. The need for angiography, however, especially
after trauma, is debatable. The vast experience gained in
reconstructive microsurgery has enabled us to become familiar with the
“vascular” anatomy in all regions of the body to optimize the selection
of recipient site vessels. A meticulous clinical evaluation (with
Doppler mapping) can provide valuable information without the need for
recipient-site angiography (71).

The proper selection of recipient vessels is essential
for the success of free tissue transfer, especially when the transfer
is to the lower extremity. However, general agreement on which vessels
to use has not yet been reached. Conflicting data have been reported on
the survival and outcome of the transferred flaps, depending on the
vessel used or the location of anastomosis proximal or distal to the
zone of injury. For example, the anterior tibial vessels may be
preferred for their easy accessibility, whereas the posterior tibial
vessels are strongly advocated by others.

Park et al. (91) developed an
algorithm for recipient vessel selection in free tissue transfer to the
lower extremity. Based on their experience, the most important factors
influencing the site of recipient vessel selection were the site of the
injury and the vascular status of the lower extremity. The type of flap
used, method, and site of microvascular anastomosis are less important
factors in determining the recipient vessels.

The timing of the wound closure using microsurgical
techniques is important. In severe injuries of the lower extremity with
associated soft-tissue defects, early aggressive wound debridement and
soft-tissue coverage with a free flap within 5 days has been found to
reduce postoperative infection, as well as decrease flap failure,
nonunion, and chronic osteomyelitis (19,20). Godina (39)
emphasized the importance of radical debridement and early
full-thickness soft-tissue coverage either acutely or within the first
72 hours.

Lister and Scheker (70) reported
the first case of an emergency free flap transfer to the upper
extremity in 1988; they defined the emergency free flap as a “flap
transfer performed either at the end of primary debridement or within
24 hours after the injury.” Yaremchuk and colleagues (118)
recommend that flaps be transferred between 7 and 14 days after injury
after several debridements. The argument in favor of this approach is
that the zone of injury, which often may not be apparent at
presentation, can be determined by serial debridements performed in the
operating room over several days.

When deciding to perform a primary closure with a free
flap, two key factors should be considered: the presence of an exposed
vital structure and the risk of infection. A vital structure is defined
as “one that will rapidly necrose if not covered by adequate soft
tissue” (21). The decision of what constitutes
a vital structure depends on circumstances. Tissues such as vessels,
nerves, joint surfaces, tendons, and bone denuded of periosteum may
desiccate, die, and lead to infection when they are left exposed for
long periods of time. When considering primary versus delayed coverage,
take into account the risk of leaving the vital structure exposed and
what functional deficit would occur if it were lost.

The risk of infection is the second important factor
that should be considered because it may jeopardize the limb, the
quality of the functional recovery, or the free flap. As the risk of
infection increases, the wisdom of primary closure with a free flap is
reduced. Debridement of the wound is the most powerful surgical tool to
reduce the risk of infection of the wound. If radical debridement is
not possible, then it is not safe to perform primary free flap
transfer. Another perspective is that the capability to perform free
tissue transfer allows the surgeon increased freedom to perform radical
debridement and may actually reduce the risk of infection (86).
The mechanism of injury, the elapsed time since injury, and the degree
of contamination of the wound determine the risk of wound infection. In
an acute, sharp noncontaminated injury, when closure would be routinely
performed if there were no skin loss, there seems to be little reason
not to consider an emergency free flap.

Microsurgical procedures are major surgical procedures.
Carefully evaluate the cardiovascular and pulmonary status. Nutritional
assessment is of particular importance because this will influence
healing, particularly in trauma and tumor patients. In elective cases,
patients in a high-risk category may need preoperative nutritional
supplements (7).

The lateral arm flap (Fig. 35.16)
can serve as an innervated fasciocutaneous flap or as a
deepithelialized subcutaneous fascial flap. The lateral arm flap is
based on the posterior radial collateral vessels (PRCA). The artery is
a direct continuation of the deep brachial artery. The draining veins
of this area are the venae comitantes of the PRCA. The pedicle length
is approximately 7 cm. The external diameter of this artery is usually
1.5 to 2.0 mm but sometimes can be smaller, even 0.8 mm. The vein’s
diameter ranges from 2.0 to 2.5 mm. The anatomy of this vascular
pedicle is constant, in contrast with the medial arm flap, which has a
more variable vascular supply.

The lateral arm flap is innervated by the posterior
brachial cutaneous nerve, a proximal branch of the radial nerve (C5—6),
giving the flap potential as a sensate flap. Additional sensory supply
comes from the posterior antebrachial cutaneous nerve, which divides at
the distal upper arm, with the upper branch supplying the posterior
inferior upper arm and the lower branch supplying the lateral side of
the arm and elbow (82).

The dimensions of the skin flap is approximately 8 × 15 cm².
The surface marking that is important in planning is a line that joins
the deltoid insertion with the lateral epicondyle (this line marks the
lateral intermuscular septum and the course of the PRCA). Design a flap
with this line as the central vascular axis. Include the deep fascia in
the flap. It also can be harvested based on the PRCA pedicle alone.
This is advantageous in cases in which thin well-vascularized coverage
is required and for coverage of areas where tendon gliding is required (119).

The distal territory is thin and is innervated by the
lateral brachial cutaneous nerve of the arm; it is often hairless. In
addition, vascularized bone (humerus) may be harvested with this flap
for composite reconstruction (52).

The periostal blood supply from the PRCA will allow a
vascularized bony segment 10 cm long and 1 cm wide to be included with
the skin flap.

The radial forearm flap (Fig. 35.17)is
a thin, well-vascularized fasciocutaneous flap on the ventral aspect of
the arm. This flap was widely used in China before it was popularized
in the Western literature (88,105).
The flap is based on the radial artery, which can achieve a 20 cm
pedicle and has a diameter of 2.5 mm. This pedicle length facilitates
microsurgical anastomosis out of the zone of injury. The venous
drainage is through the venae comitantes of the radial artery, but the
flap can include the cephalic vein, the basilic vein, or both. The flap
can contain the lateral antebrachial cutaneous nerve or the medial
antebrachial cutaneous nerve and serve as a neurosensory flap. The size
of the flap can be 10 × 40 cm². A portion of the radius can be included as a vascularized bone with this flap (29).
The advantages of this flap are its long pedicle and potential sensory
innervation. The quality of the bone from the radius is mainly cortical
and not of any substantial volume (107). Including the bone in the radial forearm flap can lead to fracture of the radius.

Preliminary tissue expansion will increase the flap
dimensions; more important, it will allow direct closure of the donor
defect (76).

If the radius is harvested as vascularized bone, less
than 40% of the cross section of the radius should be harvested, and
the wrist and forearm should then be put in a cast for 3 to 4 weeks.
Avoid injury to the peritenon covering the tendons of the flexor carpi
radialis, brachioradialis, and finger flexors because its loss can lead
to skin graft failure and even loss of the tendons.

In most cases, the donor site requires a skin graft for closure, which leaves a scar in a visible place.

The scapular flap (Fig. 35.18) is probably the workhorse of skin flaps. It is a thin, usually hairless skin flap from

the posterior chest and can be deepithelialized and used as subcutaneous fascial, pedicled, or free flap.

The flap is perfused by the cutaneous branches of the
circumflex scapular artery (CSA) and drained by its venae comitantes.
The CSA is a major tributary of the subscapular artery; it is the
artery supplying blood to the scapula, the muscles that attach to the
scapula, and the overlying skin. The length of the pedicle is 5 cm, and
the diameter of the artery is 2.5 mm. The vascular pattern of this
territory makes it possible to raise multiple skin flaps on a single
vascular pedicle or to harvest the lateral border of the scapula as an
osteocutaneous flap for a complex reconstruction.

The cutaneous territory can be 20 × 7 cm² and
can be divided in two components: a horizontal territory (horizontal
scapular flap) and a vertical territory (parascapular flap) based on
the branches of the CSA after the vessel courses through the triangular
space.

Innervated by the lateral posterior cutaneous branches
of the intercostal nerves, this flap has no potential for being used as
a sensate flap. Preliminary expansion of the territory of the scapular
flap will increase the flap dimensions and permit direct donor site
closure.

The dorsalis pedis flap (Fig. 35.19) is a thin sensate fasciocutaneous flap from the dorsum of the foot. It is based

on the dorsalis pedis artery, which originates from the anterior tibial artery and its venae comitantes (72).
The length of the pedicle is 6 to 10 cm, and the diameter of the artery
is 2 to 3 mm. The nerve supply comes from the branches of the deep and
superficial peroneal nerves. The size of the flap is 6 × 10 cm²,
and it can be raised as a skin flap alone or in combination with the
second metatarsal bone as an osteocutaneous flap or in combination with
first- and second-toe transfer (83).

The flap can be used in the upper extremity to cover
joints and tendons, and in microvascular transplant of
metatarsophalangeal joints in children (78).

The donor site morbidity is of concern with the use of
this flap; it can include difficulties in primary healing with the need
for skin grafts, and complications of lymphedema, and hypertrophic
scarring of the foot (99).

The groin flap (Fig. 35.20)
provides a large skin and subcutaneous tissue territory based on the
superficial circumflex iliac artery (SCIA) and vein (SCIV). The length
of the pedicle is 2 cm, and the diameter is 1.5 mm. The dimension of
the flap is approximately 10 × 25 cm².

Preliminary expansion of the lateral groin skin beneath
the deep groin fascia expands flap dimensions and allows direct donor
site closure.

The flap can be modified, including the sheets of
external oblique aponeurosis for reconstruction of a tendon-like
structure to replace the Achilles tendon or reconstruction of the
calcaneus with a composite graft including the groin flap and iliac
crest bone (113).

The complexity of the vascular anatomy and the small
diameter of the superficial circumflex iliac artery make this flap less
popular than other free skin flaps (25).

The temporoparietal fascial flap (Fig. 35.21)
can be used as a fascial or fasciocutaneous flap. The fascia covers the
temporal muscle extending over the temporal fossa and lies superficial
to the deep temporal fascia covering the

temporalis muscle. It continues as the galea beyond the limits of the temporal fossa.

Vascular pedicle: The superficial temporal artery (STA)
is the terminal branch of the carotid artery. The length of the artery
is 4 cm, and the diameter of the artery is 2 mm. The course of the
vessels is on the fascia from the preauricular area into the temporal
fossa. The sensory nerve supply comes from the auriculotemporal nerve.
The size of the flap is 12 × 9 cm² (1).

This flap is ideally suited for covering small defects
of the foot, ankle, Achilles tendon, and hand. The minimal thickness of
this well-vascularized flap prompts some authors to describe the
technique as a “microvascular transplantation of a recipient bed” (12). This flap is useful for burns, particularly when joint spaces or tendons are exposed after debridement (23).

The following sections on each donor muscle flap include information on (1) the muscle’s origin and insertion, function, vascular supply, innervation, and pedicle length; (2) the flaps size, functional loss on removal, and elevation; and (3) any special problems that may be encountered in their use.

The classification of muscle type is based on five patterns of muscle circulation (81).
A muscle for free tissue transfer must be able to survive on one
vascular pedicle that is dominant and that will support the entire
muscle mass. Classification is as follows:

Unclassified potential transfers include fillet flaps
and combination flaps such as the latissimus dorsi–serratus anterior
muscle flap based on one dominant pedicle (thoracodorsal artery).

The fibula flap can be raised as an osteoseptocutaneous
or isolated bone segment. The length of the bone can be up to 25 cm.
The dominant pedicle is the peroneal artery and vein. The length of the
pedicle is 2 cm; the diameter of the artery is up to 2.5 mm, and the
vein diameter is 3 to 4 mm.

The course of the pedicle is posterior to the fibula
through or beneath the flexor hallucis muscle. The sensory nerve supply
is via the superficial peroneal nerve.

The skin territory is located on the lateral leg, and the size of the flap can be 8 × 15 cm². The skin blood supply is based on septocutaneous and musculocutaneous perforating vessels.

A composite (osteomusculocutaneous, osseous muscle)
transfer can include the superior anterior iliac crest with overlying
skin, and a portion of contiguous muscle can be harvested.

The blood supply is the deep circumflex iliac artery
(DCIA) and venae comitantes. The pedicle length is 6 to 8 cm, and the
artery diameter is 2 to 2.5 mm. Skin territory can be 6 × 12 cm². A branch of T-12 supplies the skin portion of the flap.

The omentum is a visceral structure containing fat and
blood vessels within a thin membrane. It extends from the stomach to
the transverse colon and beyond, covering the anterior peritoneal
contents.

The omentum has two dominant pedicles: a right
gastroepiploic artery and vein with a length of 6 cm and an artery
diameter of 2 to 3 mm, and a left gastroepiploic artery and vein with a
pedicle length of 4 cm and artery diameter of 2 mm. The omentum may be
as large as 40 × 60 cm².

Prior intraabdominal surgery may preclude use of the omental flap because of extensive omental inflammatory adhesions.

The pliability and rich lymphatic network of the omentum
make it ideal to fill cavities and fight infection. The omentum is
particularly ideal for obliteration of irregular dead space cavities
and thus has been effectively used in providing coverage after
saucerization for chronic osteomyelitis (111).

Insert a nasogastric tube for 24 to 48 hours after the
operation to decompress the stomach. This prevents gastric distention,
which, among other things, might dislodge any of the vascular ligations
along the greater curvature.

Monitoring of free tissue transfer is essential to
ensure transplant success. Many different monitoring devices and
techniques have been used with varying levels of success.

An ideal flap monitoring should satisfy several
criteria. It should be harmless to the patient and the flap, objective,
reproducible, applicable to all types of flaps, and inexpensive. It is
important that any monitor be capable of prolonged monitoring and
respond rapidly to circulatory changes. Postoperative monitoring
techniques can be grouped in four categories: (1) clinical evaluation, (2) direct vessel monitoring, (3) indicators of tissue circulation, and (4) metabolic parameters related to perfusion (17).

Success of free tissue transfer should be on the order
of 95% to 99%. Acute complications occur usually in the first 48 hours
and include venous thrombosis, arterial thrombosis, hematoma,
hemorrhage, and excessive flap edema.

Arterial insufficiency can be recognized by decreased
capillary refill, pallor, reduced temperature, and the absence of
bleeding after pin prick. This complication can be caused by arterial
spasm, vessel plaque, torsion of the pedicle, pressure on the flap,
technical error with injury to the pedicle, a flap harvested that is
too large for its blood supply, or small vessel disease (due to smoking
or diabetes). Management of arterial compromise requires prompt
surgical intervention to restore the blood flow (110).
Pharmacologic intervention includes vasodilators, calcium blockers, and
anticoagulants for flap salvage presenting with arterial insufficiency (90).

Venous outflow obstruction can be suspected when the
flap has a violaceous color, brisk capillary refill, and normal or
elevated temperature, and produces dark blood after pin prick. Venous
insufficiency can occur due to torsion of the pedicle, flap edema,
hematoma, or tight closure of the tissue over the pedicle. The venous
outflow obstruction can result in extravasation of the red blood cells,
endothelial breakdown, microvascular collapse, thrombosis in the
microcirculation, and finally, flap death. Given the irreversible
nature of the microcirculatory changes in venous congestion that occurs
even after short periods of time, venous compromise must be recognized
as early as possible.

These complications can occur alone or in any
combination. The clinical observation and monitoring of the patient
(such as with laser Doppler) should alert the surgeon, who has to
decide between conservative and operative

intervention.
Conservative treatment may include drainage of the hematoma by the
bedside release of a few sutures to decrease pressure. In cases of
venous congesion, leeches may be helpful if insufficient venous outflow
cannot be established despite a patent venous anastomosis (Fig. 35.26; see also COLOR FIG. 35.26).
The leeches inject a salivary component (hirudin) that inhibits both
platelet aggregation and the coagulation cascade. The flap is
decongested initially as the leech extracts blood and is further
decongested as the bite wound oozes after the leech detaches (110).

Occasionally, free flaps, despite early return to the
operating room for vascular compromise, do fail. Options for management
include the performance of a second free tissue transfer, noting the
technical or physiologic details that led to initial failure. Most of
the time, free tissue transfers that fail are due to technical errors
in judgment, whether they be flap harvest, compromise of the pedicle
during the harvest, improper microvascular technique during
anastomosis, improper insetting resulting in increased tissue tension
and edema, or postoperative motion of the extremity resulting in
pedicle avulsion. Although this is rare, it does occur.

The operating surgeon must then decide how to mannage
this patient, based on several factors. Obviously, if a patient
required a free flap in the first place, a second free flap should be
considered. If a decision is made not to redo the flap, it could be
left in place using the so-called “crane principle” in hope that
underlying granulation will be sufficient such that skin grafting can
be performed once the necrotic flap is removed.

The Crane principle can be applied to cases where a
local flap or free tissue transfer fails in part or totally. The failed
flap serves as a biologic dressing or eschar over the wound bed. If
there is no infection, leave the eschar on the wound bed and observe
for healing, evidenced by the formation of granulation tissue under the
eschar. Ultimately, the eschar can be removed and, with an appropriate
granulation bed, the wound can be skin grafted, obviating the need for
another free tissue transfer. If a granulation bed is not produced,
consider a second flap. Occasionally, failed free flaps are left in
place, provided that there is no infection. With some wound contraction
and granulation tissue taking place over time, the flap is removed and
a skin graft can be performed to reepithelialize the wound.

Delayed debridement of unsalvageable free flaps can be
considered for noncritical wounds and may obviate the need for a second
free tissue transfer to obtain wound closure (116).

We believe that a necrotic flap can become a source of
sepsis and further compromise local tissues. Remove necrotic nonviable
flaps and apply a temporary wound dressing, such as a bead pouch or
wound Vacuum Assisted closure device (KCI Company, San Antonio, Texas).
Occasionally, when flaps fail in severely compromised extremities,
consideration can be given to amputation in that the morbidity of a
second free tissue transfer and perhaps the resultant extremity state
renders the extremity less favorable for salvage and more favorable for
amputation. If a second free flap is considered, avoid the errors that
led to the initial flap compromise. It is prudent to obtain an
arteriogram, evaluate the coagulation profile, and research other
issues that led to failure.

Following the introduction of endoscopic techniques in
almost every field of surgery, the application of endoscopic techniques
for reconstructive microsurgery represents the natural evolution of
this trend. Less postoperative pain, smaller scars in the donor area,
better visualization of the operative field with the magnified video,
and better hemostasis are only a few of the advantages of these
techniques. These advantages have been reported in a recent series of
patients in which latissimus dorsi harvesting was analyzed comparing
endoscopic techniques and the traditional technique (69). Successful microvascular transplantation of gracilis muscle harvested with endoscopic guidance has been reported (34,106).

Prefabrication of flaps allows custom flaps to be
constructed based on what is required for a specific defect. The
exploration of this new frontier may increase the possibility of
reconstructive capabilities and decrease the donor morbidity of
classical reconstructions. Depending on the specific application of the
prefabrication, one or more of the following advantages may be offered:

Current clinical methods of flap prefabrication can be
considered to be based on one or more of the following fundamental
principles of reconstructive surgery:

A fourth method of flap prefabrication makes use of
recent advances in cell biology to induce the transformation of a flap
from one tissue type to another. An application of these advancements
can be found in bone and joint reconstruction, which is still most
commonly performed with less than ideal alloplastic materials and
remains a formidable challenge despite advances in free tissue
transfer. With the possibility of inducing mesenchymal tissue to
differentiate into bone, a simple muscle flap may be molded and
transformed into a vascularized bone graft of desired shape and size (53,54).