Download 0105-upper extremity microsurgery

CME
Upper Extremity Microsurgery
William C. Pederson, M.D.
San Antonio, Texas
Learning Objectives: After studying this article, the participant should be able to: 1. Understand the indications for free
flap coverage of the upper extremity. 2. Know the advantages and disadvantages of the flaps discussed. 3. Have a basic
understanding of the anatomy of the flaps discussed. 4. Have a variety of options for free tissue transfer.
The application of microsurgical tissue transfer to reconstruction of the upper extremity allows repair of significant bone and soft-tissue defects. Through the years
the approach has changed from one of simply getting the
wound covered to primary reconstruction to preserve or
regain function. A wide variety of free flaps offers the
potential to reconstruct nearly any defect of the arm and
hand. Vascularized bone transfer can be utilized to repair
large bony defects, while innervated free muscle transfer
can replace missing muscle function. The total array of
flaps and their indications is beyond the scope of a single
discussion, but this article focuses on a few flaps that have
found application for coverage and functional restoration
in the hand and upper extremity. (Plast. Reconstr. Surg.
107: 1524, 2001.)
will discuss options for the reconstruction of
the upper extremity with free tissue transfers.5,6
APPROACH
The topic of upper extremity microsurgery is
a wide one, and for the purposes of this discussion, it will be divided into two areas: coverage
and functional reconstruction. Although many
situations will be encountered in which softtissue coverage is the only requirement, it
should not be forgotten that coverage and
functional reconstruction can be accomplished
in one step with the appropriate application of
microsurgical tissue transfer. In assessing a
wound of the upper extremity, the surgeon
should first decide on the ultimate goal of the
reconstruction. This will be predicated on
many factors, not the least being the patient’s
age, occupation, other injuries, and future
plans. The surgeon should have in mind a plan
in terms of how the initial procedure fits with
what else may be necessary in the future. Although soft-tissue coverage may be the first
priority in a patient with an avulsion injury to
the hand, the type of flap chosen not only
should allow later surgery but should be performed in a way that will maximize later efforts.
When a patient initially presents with a
wound of the upper extremity, the surgeon
must carefully assess the wound and make a
number of important decisions. The assessment of the injury should take into account the
status of the wound (clean or dirty), the presence or absence of fractures (and/or bony defects), and the status of neurovascular struc-
Since its inception, microsurgery has found
wide application in reconstructing the upper
extremity. Digital replantation, which was first
performed in 1968,1 probably represents the
pinnacle of reconstruction in the hand, because it allows exact replacement of the missing part. The replacement of missing parts in
kind was extrapolated in 1969, when Cobbett2
reported the first great toe transfer to replace a
missing thumb. Although the first successful
free flap reported in 19733 was to the lower
limb, the technique of free tissue transfer rapidly became incorporated into reconstructive
surgery of the hand and arm. Through the
study of vascular anatomy of potential donor
sites, the plastic surgical community has given
itself a wide variety of available tissues for reconstructive purposes.4 Almost any composite
defect of the upper limb can now be reconstructed with a free tissue transfer. This article
From the Hand Center of San Antonio and the Departments of Surgery and Orthopaedic Surgery, the University of Texas Health Science
Center at San Antonio. Received for publication April 20, 2000; revised August 25, 2000.
1524
Vol. 107, No. 6 /
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UPPER EXTREMITY MICROSURGERY
tures (distal vascular supply and nerve
function). All of these considerations are important in choosing the proper approach to
reconstruction. Clean wounds with defects in
structures other than soft-tissue coverage
should be considered for primary reconstruction. Untidy wounds will usually require debridement and, although they may require free
flap soft-tissue reconstruction, repair of other
structures may best be left until a closed wound
is obtained.
PLANNING
Regardless of the type of flap chosen, preoperative planning is essential for success. The
primary issue in microvascular tissue transfer is
vascular access for vessel anastomosis. Although the upper extremity has a rich vascular
supply, trauma or tumor extirpation may limit
the available choices for anastomosis. In most
patients, the hand will maintain adequate perfusion if only one of the major arteries (radial
or ulnar) is open. If the hand is viable and
either one of these pulses is strong, I think that
arteriography is unnecessary. If there is any
question regarding the status of hand perfusion, an arteriogram should be performed, especially if free flap transfer is contemplated. In
choosing where to perform vascular anastomoses, a site out of the zone of injury should be
chosen. If one is not sure, the vessels should be
explored and followed proximally until there is
no blood staining in the vascular sheath. For
coverage of the hand, anastomosis is usually
performed to either the radial or ulnar arteries. For the radial side of the hand and dorsum,
the radial artery in the snuffbox may be used
for end-to-end or end-to-side anastomosis. If
both the radial and ulnar arteries are patent,
an end-to-end anastomosis at this level should
not compromise circulation to the hand. In
most instances, however, it is probably safer to
perform an end-to-side anastomosis. For coverage of the forearm, anastomosis can be performed to either of these vessels or to the
brachial artery in the antecubital fossa. If there
is significant trauma to the forearm, a proximal
end-to-side anastomosis to the brachial artery is
preferable. In the upper arm, most anastomoses will be to the brachial system. Venous anastomosis is usually best done to one of the superficial veins of the forearm, because the
deep venous system is small and anastomosis
may be difficult. The surgeon must be sure that
there is no proximal injury to the chosen vein
to avoid outflow obstruction and thrombosis.
For most free flaps, a two-team approach is
the most expeditious. The recipient site can be
debrided and vessels made ready for anastomosis while the flap is dissected. This may not be
feasible in some settings, especially if the chosen flap is to come from the injured arm (i.e.,
the lateral arm flap). If there is inadequate
surgical help for this approach, the wound is
debrided and measured, and then an appropriate flap is harvested. Once the flap has been
harvested, it is left attached by its pedicle for
perfusion while the vessels are dissected on the
recipient limb. When the recipient vessels are
ready, the pedicle is divided and the flap is
transferred.
COVERAGE
The approach to wounds of the upper extremity should follow the usual parameters of
soft-tissue reconstruction. Many wounds can be
covered with a split-thickness skin graft or with
regional flaps, particularly in the hand. The
ultimate morbidity of any local or regional flap
must be considered, however, especially in relation to later hand function. Because the hand
is highly visible, the cosmetic aspect of certain
local and regional flaps must be considered as
well. Although certain wounds may be adequately covered with a flap from the same extremity, one should consider what offers the
best coverage in terms of the overall reconstruction.7 This will often lead to the use of a
free flap for many hand wounds. The following
discussion will cover the considerations regarding which flaps may be used for soft-tissue reconstruction in the hand and arm.
The wound must be considered both in
terms of its tidiness and size. The first step
before flap coverage is always conversion of a
grossly untidy wound to a clean one. Debridement should not be compromised to avoid
making the wound larger, because almost any
wound in the upper extremity can be covered
with free tissue transfer. This concept was promoted by Godina, who coined the term
“necrectomy”8 to describe the removal of all
nonviable and contaminated tissue. In this approach, intact neurovascular structures are left
in place and large bony fragments may be
cleaned and replaced in their anatomic position if adequate coverage can be obtained.
Once the wound has been debrided, flap selection should be considered. Dirty wounds are
1526
usually best covered with muscle, because muscle manages infection better than skin only.8,9
Vascularized fascia also has advantages in terms
of potential contamination,10 and it may be
considered in some untidy wounds. The selection of flap coverage for a clean wound allows
the use of composite tissue in many cases. Particularly in the case of tumor extirpation, the
reconstructive surgeon may have the option of
reconstructing a complex defect with a single
flap. Although many smaller wounds in the
upper extremity are amenable to local or regional flaps (i.e., the pedicled groin flap), this
discussion will center on the use of free flaps
for wound management.
Muscle Flaps for Coverage
The selection of which muscle to transfer is
based largely on the experience of the surgeon, but the “workhorses” in large wounds of
the upper extremity are the latissimus dorsi
and rectus abdominis muscles. Smaller defects
can be covered with either a portion of one of
these muscles or a smaller muscle flap, such as
the serratus anterior or gracilis muscle.
Latissimus dorsi. The latissimus dorsi muscle is
a large muscle of the back and shoulder, and its
vascular supply for free transfer is based on the
subscapular-thoracodorsal system.11,12 The pedicle is lengthy (8 to 11 cm) and has a relatively large
diameter proximally (up to 6 mm). This is the
largest single muscle available for transfer, and its
area of coverage can be expanded by including a
portion of the serratus anterior muscle through
its branch off the thoracodorsal artery.13 It can be
used as an innervated muscle because of the single thoracodorsal nerve,14 but the latissimus is
generally used to cover large, degloving-type
wounds. Its advantages are that it has a totally
reliable vascular supply and is very large. Its primary disadvantage is that the patient must be
turned in the lateral decubitus position for muscle
harvest. If the contralateral muscle is taken, the
patient can be turned on the side, and the injured
arm can be prepared simultaneously with muscle
harvest (assuming that appropriate surgical assistance is available). It can be taken as a myocutaneous flap, but for most indications in the upper
extremity, only the muscle is taken; it is then covered with a split-thickness skin graft. The donor
site is easily closed, but seroma formation is a
common sequelae of this donor site. The functional morbidity from the loss of muscle is minimal in most patients, but its use should be avoided
PLASTIC AND RECONSTRUCTIVE SURGERY,
May 2001
in patients who must adduct the arm strongly
(crutch-walkers and paraplegics).
Rectus abdominis. The rectus abdominis is a
muscle widely used in microsurgery, primarily
as part of the TRAM (transverse rectus abdominis musculocutaneous) flap for breast reconstruction. This muscle is on the anterior abdominal wall and runs from the medial lower
ribs to the pubis. It lies in a sheath composed
anteriorly of continuations of the external and
internal oblique muscle layers. The posterior
sheath is a continuation of the transversus abdominis, but in the lower abdomen, it is quite
thin (below the linea semicircularis). This is a
fairly large muscle, and it has a reliable vascular
pedicle based on the deep inferior epigastric
system. The pedicle is fairly long (5 to 7 cm),
and its diameter is fairly large (2.5 to 3 mm).
The rectus abdominis muscle will cover most
defects of the hand and forearm,15,16 and it will
cover large defects of the forearm if most of the
muscle is harvested and it is placed “barber
pole” fashion around the arm.17 The advantages
of this muscle are that it has a reliable vascular
pedicle and may be taken with the patient supine. The disadvantage of this muscle is that a
hernia can result from its harvest if fascia is
taken (for a myocutaneous flap) or if the anterior sheath is weak. For coverage of the upper
extremity, this muscle is usually harvested without a skin paddle and covered with a split-thickness skin graft.
Serratus anterior. This muscle is very useful
for covering smaller hand defects.13,18 It consists
of nine slips of muscle that connect from the
ribs at the anterior axillary line to the tip of the
scapula. The lower slips are vascularized by a
branch coming off the thoracodorsal artery,
and the upper slips are vascularized by a branch
of the lateral thoracic artery. The lower three
slips may be taken individually or together as a
free muscle flap based on the thoracodorsal
pedicle. This dissection is tedious because
branches of the long thoracic nerve may be
intertwined with the vessels, and damage to the
nerve supplying the remaining slips of muscle
can lead to winging the scapula.19 The branch
to the serratus is usually taken with the proximal
thoracodorsal vessels, both to lengthen the
pedicle and because of the larger diameter of
the proximal vessel. This can give a very lengthy
pedicle (15 to 17 cm) with a large diameter (3
to 6 mm). The primary advantage of this muscle
is its small size and lengthy vascular pedicle. The
disadvantages of this muscle are the potential
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UPPER EXTREMITY MICROSURGERY
for long thoracic nerve injury and the decubitus
position necessary for harvest. This flap can be
used to cover the dorsal or palmar hand and
first webspace. It has the potential for innervation with a branch of the long thoracic nerve,
but this application would be limited in the
upper extremity.
Although there are certainly other muscles
available for use in the upper extremity, these
three will afford coverage for almost any wound.
The gracilis muscle will be discussed below in the
section on functional reconstruction.
Fascia and Fasciocutaneous Flaps
In the case of clean traumatic wounds or tumor excision, a cutaneous free flap may offer the
best option for reconstruction. These flaps usually offer a better cosmetic result than a muscle
covered with a skin graft, and they are probably
better in terms of performing later surgery
through or under the flap. This is particularly
true in the case of later tendon surgery, where
the fascia contained in these flaps may offer a
better gliding surface for tendons. In a hand with
multiple digital amputations, a cutaneous flap is
better in terms of providing coverage for later toe
transfer as well. There are any number of fascial/
fasciocutaneous flaps available, but the primary
flaps are the radial forearm, lateral arm, scapular,
and temporoparietal fascial free flaps. Although
the groin flap is used in some centers as a free
flap and has some definite advantages (primarily
donor-site cosmetics), the variability and limited
length/size of its vascular pedicle make it a second level choice for free transfer in most centers.
Radial forearm free flap. This flap offers almost ideal characteristics for hand reconstruction.20 Its primary application is as a pedicled
flap based on reversed flow through the distal
radial artery and venae comitantes.21 Nonetheless, it may be used as a free flap in certain
instances, and it affords excellent hand coverage. This flap can be raised anywhere along the
course of the radial artery, and a skin island
from very small to quite large may be taken. The
radial artery provides a large caliber vessel for
anastomosis, and it may be used for revascularization of the distal limb if necessary as a “flowthrough” free flap. The venous drainage is
through the dual concomitant veins of the radial artery, but larger flaps can be drained using
cutaneous veins. There has been some controversy regarding the primary venous drainage of
these flaps, but the venae comitantes offer reliable drainage, even in the absence of super-
1527
ficial veins. This flap may be innervated by anastomosis of the lateral antebrachial cutaneous
nerve, part of which is invariably in the flap. The
quality of sensation in such reinnervated flaps is
not great, but it may be useful. If the patient has
a palmaris longus tendon, it may be taken in the
flap as well, and this provides an excellent option for tendon reconstruction, especially on
the dorsal hand. Because the tendon is taken
with its surrounding tissue, it has excellent gliding when transferred as part of the flap. A portion of the volar radius may be harvested with
the flap as well, and this is particularly useful in
the reconstruction of missing segments of metacarpal.22,23 The radial artery can be taken with
the fascia only; this provides a thin flap that is
particularly useful in reconstructing the palm.
The advantages of using this flap as a free flap
are its thinness, its reliability (based on the radial
artery), and the multitude of other tissues that
may be harvested with it. The main disadvantage
of this flap is the resulting donor site, which must
usually be covered with a skin graft. The donor
site is usually aesthetically unpleasant, but it
causes few functional problems. Another relative
contraindication to this flap is the loss of the
radial artery, but studies have shown that significant problems are unusual. Cold sensitivity is
seen, but this may be related to other factors.
Although the radial forearm flap is an excellent
free flap, it can usually be used as a distally pedicled island flap for hand reconstruction. If this
flap is not available for some reason as a pedicled
flap, I usually select a skin flap from another area
and do not take a radial forearm flap from the
contralateral uninjured arm.
Lateral arm free flap. This cutaneous flap
from the lateral distal upper arm is based on the
radial collateral artery, a branch of the profundus brachii.24 This vessel runs with the radial
nerve in the spiral groove and comes to lie in
the intermuscular septum between the brachialis and lateral head of the triceps. It gives arterial
supply to the skin overlying the septum and to
the underlying humerus. Distal to the intermuscular septum, the posterior radial collateral artery has a rich system of anastomoses with vessels in the proximal lateral forearm, which will
allow extension of the flap onto the proximal
forearm. The pedicle for this flap is relatively
short (5 to 7 cm), and the proximal artery has
a small diameter (1.5 to 2 mm) when compared
with the flaps previously discussed. The length
of the pedicle is limited by the fact that it exits
the spiral groove with the radial nerve, and dam-
1528
age to this nerve must be avoided in dissection.
The skin paddle can be based directly over the
intermuscular septum for a smaller flap or extended distally for a larger one. Donor sites up
to 7 cm in width can be closed primarily, but
larger ones will require a skin graft.25 When
closed primarily, the donor site can be very
cosmetic, but in some patients, the scar will
widen significantly. The lateral cutaneous nerve
of the arm is in the flap, and thus the skin can
be innervated if necessary.26 A portion of the
lateral humerus can be taken with the flap for
bony reconstruction, based on its vascular supply from the overlying pedicle.27
The lateral arm flap is purported to be a
“thin” flap, but because of the tissue in the
intermuscular septum, it is a bit bulky when
placed on a flat recipient site (i.e., the back of
the hand). This problem can be avoided by
using the fascia only, which also decreases donor-site problems.25,28 The primary advantages
of this flap are that it can be taken from the
ipsilateral arm (of injury),29 it avoids the sacrifice of a major vessel, and the donor site can
often be closed primarily. The primary disadvantages of the lateral arm flap are its somewhat limited size and the short and smalldiameter pedicle. It is very useful in covering
small defects of the hand and works very well in
the first webspace. In thin patients, it can be
used to cover a degloving injury of the thumb,
with the added benefit of reinnervation by the
cutaneous nerve (Fig. 1).
Scapular flap. The scapular and parascapular flaps offer a versatile large skin flap to
cover defects in the upper extremity (Fig.
2).30 The vascular supply is based on the
circumflex scapular vessels, which branch
from the subscapular system.31 The pedicle
for this flap is long (4 to 6 cm) because the
subscapular vessels can be taken if necessary,
and this provides vessels of large diameter at
the takeoff from the axillary artery. The vessels lie in the fascia with branches to the
overlying skin. There are two primary
branches, thus giving rise to the “transverse”
scapular flap, which is sited transversely
across the back, and the “parascapular” flap,
which is sited obliquely down the back. Based
on this vascular supply, a very large skin flap
can be designed that will cover most defects
of the forearm and/or arm.32 Although a
number of cutaneous nerves enter the skin,
there is not a dominant nerve to this area,
and thus this flap has poor potential for in-
PLASTIC AND RECONSTRUCTIVE SURGERY,
May 2001
nervation. Branches from the primary pedicle feed the lateral surface of the scapula,
and a portion of this bone can be taken to
repair bony defects. This bone is quite flat,
however, and its primary indication is in the
reconstruction of smaller defects in the
hand. Donor sites in the 8-cm range can
usually be closed primarily, but this is usually
limited to the parascapular design of the
flap.
The primary advantages of this flap are the
length and diameter of its pedicle, along with its
potential large size. The primary disadvantage of
this flap is the need for turning the patient to
harvest it. The scapular flap is an excellent choice
to cover large wounds of the forearm, and it can
be used in place of a pedicled groin flap for hand
coverage. It can be combined with the latissimus
dorsi and serratus anterior muscle flaps on a
single pedicle to provide a huge amount of tissue
and to cover different surfaces of the hand and
arm (Fig. 3).33,34
Temporoparietal fascia flap. The temporoparietal fascia offers a flap of specialized tissue that
has great utility in hand reconstruction.35 This
flap is supplied by the superficial temporal artery and vein, and it has a pedicle in the 2- to
3-cm range that is about 1.5 to 2.5 mm in diameter.36 The temporal fascia lies on the temporal region of the skull, beginning on the zygoma and running superiorly. There is a
superficial and deep layer, and both may be
taken with this flap. The use of both layers of
fascia has been promoted for use in wrapping
adherent tendons on the dorsum of the hand
after tenolysis in a scarred bed. The deep fascia
can also provide tissue for reconstructing small
tendons on the dorsal hand as well. A flap of
moderate dimensions may be taken (in the
range of 8 to 10 cm). The potential for harvesting vascularized bone with this flap exists, but
the thin, outer table bone available has few (or
no) indications in the hand. Although the donor scar is one of the best in terms of cosmesis,
the problem of alopecia exists because the superficial fascia must be dissected from just beneath the hair follicles of the scalp.
The primary advantages of this flap are its
potential to provide a gliding surface and its
good donor site (one of the best in terms of
cosmesis). The primary disadvantage of this
flap is that it is very thin and must be covered
with a skin graft. Temporoparietal fascia offers
very nice coverage for defects of the fingers
and hand, but the size of the flap is limited.37
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UPPER EXTREMITY MICROSURGERY
FIG. 1. (Above, left) Degloving injury to the thumb in a 23-year-old man. (Above, right) A piece of cloth is used for a template
for a lateral arm flap. (Center, left) The flap is marked on the lateral upper arm. (Center, right) The flap is placed. Note that the
“seam” was placed dorsally, with anastomosis of the lateral cutaneous nerve of the arm to the ulnar digital nerve of the thumb.
(Below, left) Results at 8 months. Protective sensation had returned. (Below, right) Flexion at 8 months.
This tissue does seem to improve the gliding
ability of tendons, particularly on the dorsum.
When covered with a split-thickness skin graft,
the temporoparietal fascia flap offers the thinnest coverage available (excluding other fascial
flaps). It is probably not the best choice when
later surgery through the flap is contemplated,
however.
FUNCTIONAL RECONSTRUCTION
Composite tissue transfer offers the ability to
reconstruct functional deficits with flaps containing skin, bone, joint, and reinnervated
muscle. Detailed discussion of each of these
areas is beyond the scope of this article, but a
brief outline of procedures to deal with signif-
1530
FIG. 2. (Above) The hand of a baby with dorsal wrist contracture after a burn. (Below) The hand after scar excision,
wrist release, and scapular flap.
FIG. 3. Multiple flaps are available on single pedicle. Here
a portion of serratus anterior, latissimus dorsi, and a scapular
cutaneous flap have been harvested on a single subscapular
pedicle.
icant bone loss, muscle necrosis, and digital
loss will be covered.
Free Fibula
Most bony defects in the upper extremity
can be managed with standard bone grafts;
however, long defects (⬎ 6 cm) and those
PLASTIC AND RECONSTRUCTIVE SURGERY,
May 2001
associated with recurrent failure to heal may be
candidates for microvascular bone transfer.38
Although there are several flaps available that
can include a portion of vascularized bone (iliac crest, lateral arm, radial forearm, dorsalis
pedis), the fibula osseocutaneous flap offers
the best piece of bone for reconstructing significant defects of the long bones of the upper
extremity.39,40 Smaller defects, such as those in
the hand, can be managed by one of the previously discussed flaps, with inclusion of a segment of bone. Larger defects of the radius,
ulna, or humerus will usually require a piece of
bone such as the fibula.41 The vascular supply
of the free fibula is based on the peroneal
vessels of the leg. These vessels run along the
deep surface of the fibula from just below the
tibioperoneal trunk to the level of the ankle.
Although the peroneal vessels provide a nutrient artery to the medullary canal of the fibula,
they also provide a rich periosteal blood supply
to the cortical surface. The proximal portion of
the fibula can be taken to reconstruct the radiocarpal joint, but this segment of bone gets
its primary blood supply from a branch of the
anterior tibial artery,42 which must be taken to
assure viability of this segment.
A portion of the skin overlying the fibula can
be taken with the bone, and thus compound
defects can be managed with this flap (Figs. 4
and 5). The perforators to the skin run around
the posterior aspect of the bone, and thus it is
best to include a cuff of muscle along the
posterior surface of the bone if a skin paddle is
to be included. If a skin paddle is taken, most
donor sites will require a skin graft on the
overlying muscles. The primary advantage of
this donor site is the large amount of bone that
can be taken. In adults, a total of up to 24 to 26
cm of bone may be harvested. The fibular head
should be left in place at the knee level, and 6
cm of the distal fibula should remain to avoid
problems with the ankle. In children, a screw
should be placed across the fibular-tibial joint
to avoid proximal migration of the fibula. The
disadvantages of this donor site are few: the
pedicle is relatively short (2 to 4 cm) and there
is some morbidity from harvesting, but these
do not usually present functional problems.
Innervated Gracilis Transfer
In some instances, there is a need to replace
damaged or excised muscle in the forearm or
upper arm. Although many losses can be adequately reconstructed with standard tendon
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UPPER EXTREMITY MICROSURGERY
FIG. 4. (Above, left) Humeral nonunion in a patient who had undergone seven prior procedures to attempt union. (Above, right) Intraoperative x-ray. Note that the fibula is held in place
with only two screws, while the plate spans the defect at the site of resection of nonunion. (Below)
Arm after vascularized fibular transfer to nonunion. Hemostat points to plate over fibula.
transfers, patients with significant loss of muscle substance (such as those with Volkmann’s
ischemic contracture) may benefit from reconstruction of function with a microvascular muscle transfer (Fig. 6).43 The muscles available for
this include the gracilis, latissimus dorsi, and
rectus femoris. This latissimus dorsi can be
used in the forearm as a free functional transfer,44 but it is not ideal. The rectus femoris has
been used for this in the past, but again it is not
the optimal muscle. The gracilis muscle, however, is nearly ideal for reconstruction of the
muscles of the forearm. It has adequate excursion to provide finger flexion or extension, it is
of the appropriate size (both length and
width), and it has an excellent neurovascular
pedicle. The gracilis is a muscle in the medial
thigh that runs from the pubis to the medial
tibia. It has a primary vascular pedicle (a
branch of the profundus femoris) and enters
the muscle at its undersurface about 6 to 12 cm
below its origin. The pedicle is rather short (5
to 6 cm) and of relatively small diameter (1 to
2 mm). There are usually two or three secondary pedicles that enter the muscle distally, but
the muscle is well-perfused by its primary pedicle alone after microvascular transfer. The gracilis is powered by a single nerve, the anterior
1532
FIG. 5. Results from the patient shown in Figure 4 at 2
years postoperatively. Note incorporation and hypertrophy of
the fibula.
branch of the obturator nerve, which enters
the muscle at the level of the vascular pedicle
proximally. The distal third of the muscle is
tendinous, and this tendon is ideal for attachment to the distal flexors or extensors of the
digits. The primary advantage of this muscle as
an innervated free transfer is that its size and
excursion closely match those of the muscles of
the forearm. The primary disadvantage of this
muscle for free transfers is its relatively short
and small pedicle.
The primary indication for innervated muscle transfer to the forearm is loss of muscle
mass, as in Volkmann’s ischemic contracture
or traumatic avulsion of the muscles. The prerequisites for successful innervated muscle
transfer include adequate passive excursion of
the distal joints, intact sensation in the hand,
available neurovascular structures for anastomosis, adequate distal soft-tissue for coverage
of the tendon repairs, and lack of a simpler
solution for the problem.43 In certain instances, some of these requirements can be
modified if the others are present. In general,
however, this procedure should be reserved for
those patients with a severe problem that is not
amenable to more standard solutions.
Toe Transfer
Microvascular toe transfer represents one of
the pinnacles of reconstructive surgery. The
PLASTIC AND RECONSTRUCTIVE SURGERY,
May 2001
ability to replace in kind a missing digit with a
mobile, sensate toe offers the best type of reconstruction available. Although this is a complex microsurgical procedure that should not
be undertaken without experience,45 it remains
the benchmark for thumb and most digital
reconstructions. There are a number of variations of toe transfer, and almost any tissue
needed for digital reconstruction can be transferred. These range from pulp-only transfers to
double second and third toe transfers to reconstruct the metacarpal hand. Because this is an
overview, the discussion here will be limited to
anatomy and a few technical points.
All great and second toe transfers ideally
have their vascular basis on the dorsalis pedis–
first dorsal metatarsal system. This anatomy is
highly variable, however, and a thorough
knowledge of it is the basis for safe harvesting
of these flaps. The venous drainage is based on
the dorsal superficial veins of the foot, because
the deep system that accompanies the arterial
supply is usually very small. The flaps can be
innervated by the proper plantar digital nerves
to the toe(s) and by the deep peroneal nerve,
which accompanies the dorsalis pedis/dorsal
metatarsal vessels.
Joint reconstruction. Destruction of the proximal interphalangeal or metacarpophalangeal
joint in a finger remains a formidable reconstructive problem. Although arthroplasty with
artificial joints continues to be an option in
these patients, results are poor in young, active
patients. The possibility of reconstructing a
missing finger joint with a joint from a toe
would seemingly obviate the problems associated with artificial joint replacement.
There have been a number of reports of
joint replacement in the hand with toe
joints.46 –50 The metatarsophalangeal joint and
proximal interphalangeal joints of the second
toe are used most often to reconstruct the
analogous joints in the hand. Despite early
enthusiasm for this procedure, it remains problematic. Extensor lag at the transferred joint is
common,49 –52 and complication rates are fairly
high and include vascular failure, infection,
and late joint destruction.50,52 Active range of
motion for transferred metatarsophalangeal
joints is in the 30-degree range, with less in
transferred interphalangeal joints.50 –52 In children, transferred toe joints provide some potential for growth, but reports vary on the
amount of growth obtained from the transferred epiphyses.52–54 Although this procedure
Vol. 107, No. 6 /
UPPER EXTREMITY MICROSURGERY
1533
FIG. 6. (Above, left) Intraoperative view of the forearm of a 12-year-old boy after a propeller injury. Note the disrupted median
nerve (over background). (Above, right) Intraoperative view after innervated gracilis transfer. The skin paddle for monitoring
is over the proximal muscle. (Below) Extension (left) and flexion (right) at 8 months postoperatively.
certainly has advantages over implant arthroplasty and fusion, it is a complex undertaking
and should be used selectively by surgeons with
experience.
Thumb reconstruction. Toe transfer in one of
its forms offers many of the best ways to reconstruct defects of the thumb.55 For reconstruction of the pulp of the thumb alone, only the
lateral pulp of the great toe is taken; this may be
innervated by the lateral digital and deep peroneal nerves. This flap provides excellent reconstruction for the thumb and leaves little
morbidity at the foot. For partial thumb amputations (those from the mid-proximal phalanx
level), a great toe “wrap-around” flap may be
used (Fig. 7). This modification takes only the
distal phalanx and surrounding soft tissue,
which is trimmed to approximate the circumference of the missing thumb.56,57 This technique requires the use of an intercalated bone
graft segment between the proximal phalanx of
the thumb and distal phalanx of the toe. Although this is arguably the most cosmetic type
of thumb reconstruction, it does not recon-
FIG. 7. Patient 1 year after great toe wrap-around reconstruction of the left thumb.
struct missing joints. Because it leaves the proximal phalanx intact, it has the potential to impart less morbidity at the foot than whole great
toe transfer. Wei et al58 advocate the “trimmed
toe” technique to circumvent the lack of motion
of the wrap-around flap. In this technique, the
entire great toe is trimmed, including both the
soft-tissue and bony structures, to give a recon-
1534
structed thumb of appropriate circumference.
Their report showed a reasonable return of motion in the trimmed joints.
In cases of loss of the entire thumb, the
entire great toe may be transferred. It should
be noted that the metatarsophalangeal joints
act primarily in the extension arc. To avoid
hyperextension of this joint when transferred
to the hand, a dorsal oblique osteotomy is used
to place the toe in the proper position on the
hand. The flexor and extensor tendons are
taken with a total great toe transfer, and anastomosis is ideally performed at the wrist level to
decrease the incidence of tendon adhesions.
The flexor tendon may be harvested through a
separate incision in the non–weight-bearing
surface of the arch of the foot and, if more
length is needed, another incision may be
made at the level of the tarsal tunnel. The
extensor tendon (extensor hallucis longus)
is usually taken through the dorsal incision
made for dissection of the neurovascular
structures.
Transfer of all parts of the great toe imparts
some morbidity to the foot, but the effect when
evaluated with gait studies is generally minimal. Certainly, the tradeoff of a thumb for the
loss of the great toe is usually well-accepted by
the patient. The primary disadvantage of these
techniques is their inherent complexity and,
although they offer superb reconstructive options in patients with loss of all or part of the
thumb, their application should probably be
limited to those practitioners with experience.
Digital reconstruction. The second or second
and third toes may be transferred in a manner
similar to that used with the great toe to reconstruct missing digits. A single toe transfer for a
single missing digit is generally not indicated,
and the application of this technique is generally reserved for those patients who have suffered a transmetatarsal amputation (metacarpal hand).59 Smaller portions of the second toe
can be used for pulp and/or nail losses, but this
type of procedure is usually less necessary in the
digits than in the thumb. In the case of multiple
digital loss, two fingers may be reconstructed
with either a double toe (second and third combined) from one foot60 or a second toe transfer
from each foot. The loss of the second toe only
imparts very minimal morbidity, but the loss of
two toes from one foot leaves a significant
deficit.61
PLASTIC AND RECONSTRUCTIVE SURGERY,
May 2001
CONCLUSIONS
This has been a brief overview of microsurgical reconstruction of the upper extremity.
The number of flaps available for hand and
arm reconstruction is large, and only a few
have been discussed here. There are a number
of flaps other than those discussed that have
application in the upper extremity, but I hope
this overview has given the reader a number of
options that offer a solution for most reconstructive problems. For further reading, one
should seek out one of the many texts available
on the subject.12,62,63
William C. Pederson, M.D.
The Hand Center of San Antonio
9150 Huebner Road, Suite 290
San Antonio, Texas 78240
[email protected]
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Self-Assessment Examination
Upper Extremity Microsurgery
by William C. Pederson, M.D.
1. THE LARGEST SINGLE MUSCLE AVAILABLE FOR MICROSURGICAL TRANSFER IS THE:
A) Rectus abdominis
B) Pectoralis major
C) Gluteus maximus
D) Latissimus dorsi
E) Trapezius
2. HARVEST OF THE SERRATUS ANTERIOR MUSCLE CARRIES THE RISK OF DAMAGE TO:
A) The thoracodorsal nerve
B) The pleura
C) The long thoracic nerve
D) The medial pectoral nerve
E) The axillary artery
3. THE MOST COMMON DONOR-SITE COMPLICATION OF TEMPOROPARIETAL FASCIA HARVEST IS:
A) Facial nerve injury
B) Temporal wasting
C) Temporomandibular joint malfunction
D) Alopecia
E) Necrosis of the scalp
4. A DEFINITE INDICATION FOR INNERVATED GRACILIS TRANSFER TO THE FOREARM WOULD BE:
A) Volkmann’s ischemic contracture
B) Electrical burn to the forearm
C) High median nerve injury
D) Degloving injury to the forearm
E) Radial nerve paralysis
5. THE TYPE OF GREAT TOE TRANSFER OFFERING THE BEST POTENTIAL FOR MOTION WOULD BE:
A) Great toe wrap-around
B) Whole great toe transfer
C) Trimmed great toe transfer
D) Great toe pulp transfer
E) Great toe interphalangeal joint transfer
6. THE TERM “NECRECTOMY” AS APPLIED TO WOUND DEBRIDEMENT IMPLIES THAT:
A) Only the margins of the wounds are excised
B) All tissues that may have been damaged, including nerves and vessels, are excised
C) All contaminated or nonviable tissue is excised with the exception of major neurovascular structures
D) All deep structures are left intact, regardless of contamination, because coverage with a free flap will take care of any residual
necrotic tissue or contamination
E) Only obviously necrotic tissue is excised
To complete the examination for CME credit, turn to page 1635 for instructions and the response form.