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TITLE:   FREE FLAPS FOR HEAD AND NECK RECONSTRUCTION
SOURCE:  Dept. of Otolaryngology, UTMB, Grand Rounds
DATE:    December 14, 1994
RESIDENT PHYSICIAN:     Daniel P. Slaughter, M.D.
FACULTY:                Christopher P. Rassekh, M.D.:w
DATABASE ADMINISTRATOR: Melinda McCracken, M.S.
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"This material was prepared by resident physicians in partial fulfillment 
of educational requirements established for the Postgraduate Training 
Program of the UTMB Department of Otolaryngology/Head and Neck Surgery 
and was not intended for clinical use in its present form.  It was 
prepared for the purpose of stimulating group discussion in a conference 
setting.  No warranties, either express or implied, are made with respect 
to its accuracy, completeness, or timeliness.  The material does not 
necessarily reflect the current or past opinions of members of the UTMB 
faculty and should not be used for purposes of diagnosis or treatment 
without consulting appropriate literature sources and informed professional 
opinion." 

INTRODUCTION

Free flap technology is now allowing the head and neck oncologist to
offer restoration of form and function following large tumor
resections. Free flaps carry several advantages over traditional
local pedicled flaps including: immediate functional and aesthetic
reconstruction, simultaneous two team approach, large variety of
donor sites, unrestricted flap positioning and reach, a large amount
of composite tissue, potential for motor and sensory reconstruction,
improved vascularity, and primary placement of osteointegrated
implants. Disadvantages include: microvascular expertise required,
labor intensive requiring team approach, recipient vessels may be
unavailable or unusable, less than ideal color and texture match,
functional disability at donor site.

PREOPERATIVE PLANNING

The combined efforts of the oncologic surgeon and the reconstructive
surgeon require extensive preoperative planning and coordination of
efforts. Sound preoperative judgement in patient selection, donor
site selection, and tumor extirpation approach can set the stage for
ultimate success. One must consider if the patient can tolerate a
lengthy procedure both intraoperatively and postoperatively. Patients
with poor pulmonary reserve and alcoholics with recent detoxification
would be poor candidates. Patients with severe peripheral vascular
disease, connective tissue disorders, morbid obesity, vasculitis,
coagulopathy, and polycythemia may be poor candidates. Smoking should
be discontinued for at least one week prior to surgery. Age alone is
not a contraindication. Donor site considerations include functional
and aesthetic needs, degree of bulk required, the need for carotid
coverage, the surface area of defect requiring coverage,the need for
external versus internal lining, and need for bone. One must be sure
that no previous trauma or surgery has been performed in the proposed
donor site area. History of radiation to the donor site area or
intravenous drug use in the area also needs to be questioned.
Informed consent is paramount as the potential for significant
morbidity, including a wide range of salvage operations, is possible.
Photos should be taken to clearly demonstrate the extensiveness of
the disease process

OPERATIVE PLANNING

The oncologic surgeon needs to function as the coordinator of all the
other health care professionals involved in the case. The positioning
of the bed and the patient along with the specifics of monitoring
must be discussed with the anesthesiologist and OR nursing staff in
advance. Details such as the room temperature, compressive leg
stockings, horseshoe head holder, and blood availability must be
discussed with the circulating nurse. The oncologic surgeon should
lay out a plan with the reconstructive surgeon detailing the order of
resection and reconstruction to maximize simultaneous operating and
therefore reduce operative time. This schedule should be laid out for
the OR nurses so they may plan when they will need additional
personal. Do not assume that the appropriate instruments, solutions,
or medications are available. Someone on the oncologic team must be
responsible for checking each detail prior to the case.

FLAP ELEVATION

Some general principles apply to all cases of flap elevation. Loop
magnification is essential for flap elevation. Gentle manipulation of
the pedicle and irrigation with warm physiosol and Papaverine
(60mg/150cc saline)is recommended. Extreme care must be taken when
ligating branches of the pedicle to prevent damage to the main
vessel. Dissect the full length of the pedicle and separate the vein
and artery to decrease anastomotic time later.

MICROVASCULAR ANASTOMOSIS

The detail of the technique will not be covered in this text but some
general principles are important to mention. The microscope will need
to be checked prior to the case to assure that it is in working
order. Check to be sure that enough 9-0 suture is available days
prior to the procedure so that it may be ordered if stocks are low.
The scrub nurse should have warm physiosol, 1% lidocaine without
epinephrine, heparin, and papaverine available for irrigation. No
systemic pressor agents (dopamine) should be used by anesthesia.
Heparin 5000u should be given IV during the last quarter of the
venous anastomosis. When the heparin is in, Dextran 40 at 25 cc/hr IV
is started. The use of heparin is somewhat controversial and is not
used in all centers.

POSTOPERATIVE MANAGEMENT

Place an anastomosogram in the chart. The pulses should be dopplered
q1hr in the SICU for 48hrs then q4hrs in the floor. As a general
guidline the pinprick test is to be performed at every visual
inspection by the surgeons (approx tid). Failure to recognized venous
or arterial thrombosis in a timely manner will result in greatly
increased chance for flap failure and increased morbidity.

SPECIFIC FLAPS

     THIN FASCIOCUTANEOUS FLAPS
     
     A. Radial Forearm Flap

     A fasciocutaneous flap based on the radial artery and its venae
comitantes or the superficial forearm veins(cephalic).  It is a thin,
reliable flap, with potential for sensory in- nervation via the
lateral or medial antebrachial cutaneous nerve. It has a long
vascular pedicle with large caliber vessels(2.5mm) making it an ideal
flap for reconstructing large defects of the face, scalp, and oral
cavity. A segment of radial bone approx. 10 cm long and 40% of the
circumference can be harvested as well but is performed less
frequently than in the past secondary to donor site morbidity. An
Allen test or doppler studies need to be performed prior to the case
to document good ulnar artery flow. The primary disadvantage is the
donor site morbidity especially if there is incomplete skin graft
take on th  paratenon Numbness in the anatomical snuff box can be
avoided by careful preservation of the superficial radial nerve. The
flap can still be used if there is poor ulnar flow if one performs a
vein interposition graft for the segment of radial artery taken. One
might consider using a different donor site rather than go to this
degree of effort. Urken has recently described the use of a modified
design that transposes not only the skin paddle for intraoral
reconstruction, but also a small monitor segment that is connected to
the primary skin paddle by a fascial subcutaneous segment of tissue.
This allows both monitoring and fascial coverage of the exposed great
vessels of the neck. Urken has also described a bilobed design of
this flap to reconstruct after significant glossectomy. One lobe
reconstructs the tongue and the other the anterior floor of mouth.
This increases postoperative tongue mobility.

     B. Lateral Arm Flap

     Much like the radial forearm flap it is a moderately thin
hairless fasciocutaneous flap that may be reinnervated for cutaneous
sensibility. Unlike the forearm flap, the donor site can usually be
closed primarily. The arterial supply is based on the terminal branch
of the profunda brachii artery and its venae comitantes, which travel
with the radial nerve in the spiral groove of the humerus. Arteria
branches run through the intermuscular septum dividing the brachialis
and the brachioradialis muscles to supply the skin of the upper arm.
The pedicle can be dissected to approximately 12 cm and is of
adequate size. The arterial supply need not be reconstituted. The
cephalic vein can also be used for venous drainage of the flap. Two
cutaneous nerves can be used both arising from the radial nerve, the
lower lateral cutaneous and the posterior cutaneous nerves.
 
     C. Lateral Thigh Flap

     This is the parallel of the lateral arm in the leg. It is a thin
fasciocutaneous flap depending on the patients body habitus. The
arterial supply is from the third perforator of the profunda femorus
system. This septocutaneous artery travels within the intermuscular
septum separating the vastus lateralis and the iliotibial tract
anteriorly from the biceps femoris posteriorly. A 12 cm pedicle with
adequate sized vessels is encountered. The flap is drained by the
venae comitantes. A large skin paddle(25 by 14 cm) can be harvested
and closed primarily. The flap can be reinnervated by the lateral
femoral cutaneous nerve of the thigh. This is a technically demanding
flap that is not used in very many centers.

     D. Scapular Flap

     This flap boasts a large surface area and the potential for
osteocutaneous free flap to achieve single stage mandibular
reconstruction. The blood supply is from the circumflex scapular
branch of the subscapular artery. The subscapular artery originates
from the third portion of the axillary artery at the inferior border
of the subscapularis muscle.  It divides into a thoracodorasal branch
to supply the lat- issimus dorsi muscle, serratus anterior muscle,
scapular tip, and overlying skin. The circumflex scapular vessels
emerge posteriorly from the axilla through a muscular triangle,
bounded by the long head of the triceps laterally, the teres major
muscle below, and teres minor muscle above.  Before exiting the
triangle the artery divides into several branches that richly supply
the lateral border of the scapula and the attached musculature. As
the circumflex artery emerges from the triangle it divides into
horizontal and vertical fasciocutaneous branches overlying the
scapula.  Scapula(horizontally oriented) or parascapular (obliquely
oriented) fasciocutaneous or osteofasciocutaneous flaps can be based
on these two fasciocutaneous branches respec- tively. Venae
commitantes accompany the arteries and the pedicle length is
approximately 5-8 cm. The bone segment potential is approximately 1.5
by 3cm thick and 10-14 cm long if one uses the entire length
including the tip.  

Two independent revascularized bone grafts may be harvested based on the
two vessels as described above.  The blood supply to the bone and the
faciocutaneous portions is carried by two separate 5cm pedicles which
allows the bone graft to be positioned independently from the skin paddle
in three dimensions. The latissimus dorsi and a portion of the serratus
muscle may be carried by the same pedicle, as described above, allowing
the largest single amount of tissue transfer described(axillary megaflap).
One could also conceivably bring a portion of vascularized rib graft with
the serratus muscle.  Significant donor site morbidity including poor
shoulder function, inability to perform simultaneous harvest, and
positioning problems, are disadvantages of this versatile flap.

     
     THICK MUSCULOCUTANEOUS FLAPS

     A.Latissimus Dorsi Musculocutaneous  Flap

     As described above this flap receives it's blood supply from the
thoracodorsal artery. This artery supplies the upper two thirds of
the muscle while the lower one third is supplied segmentally from the
intercostal arteries.  The neurovascular pedicle enters the
undersurface of the muscle approximately 8 cm below the axillary
artery. The artery will split at right angles to each other into
medial and lateral divisions. The motor nerve also splits and follows
the artery. This pattern allows the splitting of the muscle into two
independent musculocutaneous flaps.  This flap will give a large
amount of donor tissue, is well vascularized, and is ideal for
massive defects of the tongue, face, and skull base and top of head.
Bulk can be tailored by reinnervating the motor nerve. The amount of
skin versus muscle can also be tailored as the skin has an
approximately 10 cm area of random pattern viability from the  muscle
boundary. Like the scapular flap, positioning and non-simultaneous
team approach are disadvantages. The donor site can usually be closed
primarily even in large skin paddle excision.

     B. Rectus Abdominis Musculocutaneous Flap

     This flap, like the latissimus, offers a bulky flap with
tailored amounts of skin and muscle for the reconstruction of large
defects of the scalp, skull base, and maxilla. It does not require
repositioning and is conducive to simultaneous harvest. The donor
site is closed primarily.  The vasculature is based on the deep
inferior epigastric artery which is 8cm or better in length.  Various
skin paddle designs can be used based on the rich paraumbilical
arteries. It is not a sensate flap. One must take care in harvesting
not to harvest rectus muscle inferior to the arcuate line and to
perform a meticulous closure to prevent ventral hernia.
       
     C. Dorsalis Pedis Flap

     Seldom used secondary to a high donor site morbidity, delayed
ambulation, minimal bone availability, and the availability of better
donor sites. Based on the dorsalis pedis artery the second metatarsal
bone and overlying skin paddle can be harvested.

     D. Fibular Osteocutaneous Flap

     The fibula free graft receives it's blood supply from the
endosteal and periosteal branches of the peroneal artery.
Septocutaneous and musculocutaneous perforators from the peroneal
artery supply the skin over the lateral aspect of the leg. The bone
length provided by the fibula (25cm) is the longest revascularized
bone graft available and allows reconstruction of virtually any
mandibular defect. The fibula has a consistent cross-sectional area
and it's excellent periosteal blood supply allows the creation of
numerous closely spaced osteotomies for contouring. Dis- advantages
include the questionable viability of the skin paddle and the short
vascular pedicle. This flap is also one of the more difficult flaps
to dissect. Osseointegrated implants have been demonstrated to work
reliably.  Preoperative arteriography(or MRA) is necessary to exclude
anatomical abnormalities where the peroneal is the main blood supply
to the foot. One must leave a minimum of 8 cm of distal fibula to
maintain ankle motice support.

     E. Iliac Crest Osteocutaneous Flap

     The iliac crest receives it's blood supply from several vessels
but Taylor demonstrated the superiority of the groin free flap based
on the deep circumflex iliac artery. Up to 16 cm of bone and
overlying skin can be harvested. The natural curve and rich blood
supply allows numerous osteotomies for contouring for mandibular
defects. The overlying skin paddle must be designed large enough to
incorporate the large perforating vessels. This results in an overly
bulky soft tissue component in many cases. The skin paddle is also
quite subject to necrosis secondary to the shearing forces sometimes
necessary to position the skin paddle. In an effort to avoid the use
of the bulky skin paddle, an iliac crest- internal oblique
osteomusculo- cutaneous flap also based on the DCIA with
incorporation of the DCIA ascending branch can be performed. The
internal oblique is thin and pliable and serves well to reconstruct
most intraoral defects. The skin paddle can be trimmed down and serve
as an indicator of flap viability. Disadvantages of the iliac crest
free flap include the somewhat difficult dissection, risk of
herniation, poor viability of the skin paddle, bulkiness of the skin
paddle, inability to reconstruct defects over 16 cm, and significant
postoperative pain and decreased ambulation.  Advantages include the
possibility of simultaneous two team approach, robust blood supply to
the bone, and natural contouring of the bone for osteotomies for
mandibular reconstruction.


     FREE JEJUNAL AUTOGRAFT

     The jejunum serves as and excellent autograft for the
reconstruction of the cervical esophagus. It may be used either as an
end to end segment or as a free mucosal patch by splitting the
segment along it's antimesenteric border.  The segment of bowel is
usually harvested by a general surgeon using a simultaneous two team
approach. An appropr- ate segment of bowel is chosen based upon a
mesenteric vascular bundle. Generally a 20 cm segment is the longest
that may be taken. The flap is successful in more than 85% of cases
in supplying adequate deglutition once healed.  Stricture rates are
around 10%. Laparotomy rarely leads to significant morbidity although
it may limit ambulation early postoperatively. Flap loss can be a
devastating event with the production of a large fistula and
potential for great vessel hemorrhage. The jejunal flap would be an
ideal flap when a complete segment of pharynx was removed.  A radial
forearm flap that is tubed along a remaining segment of mucosa would
work well for partial pharyngectomy without the attendent morbidity
of a laparotomy.  Tracheoesophageal speech may be difficult in either
jejunal reconstruction or radial forearm reconstruction of the
pharynx. Nevertheless, primary or secondary TE puncture may be
performed in either case with roughly equal results.
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