Saturday, January 9, 2010

TUG (Inner Thigh) Flap Microsurgical Breast Reconstruction

 The following is an excerpt from a chapter I recently authored for an upcoming textbook.  It is written in medical lingo.  A version that uses more regular language more suitable for the general public will soon be posted on the Women's Plastic Surgery website.  All surgical photographs have been removed, as they may be upsetting to some readers; only diagrams are shown for educational purposes.  Read on to learn more about the TUG (inner thigh flap)!:

Introduction to the TUG Flap

            The inner thigh skin and fat based on the transverse upper gracilis musculocutaneous (TUG) flap blood supply provides an autologous donor area with several qualities complimentary to microvascular breast reconstruction.  The gracilis flap is an exciting alternative to abdominal, back or buttock tissue flaps for reconstruction of a natural looking and soft, shapely breast. 
            The gracilis muscle has a consistent and reliable blood supply, and has been well described (1, 2).  The transverse upper gracilis flap can be shaped to mimic a mastectomy specimen, providing excellent contour and projection to the breast reconstruction.  The characteristics and skin color of the TUG flap allow for immediate nipple-areola reconstruction in both immediate reconstruction following skin-sparing mastectomy and in delayed breast reconstruction alike.  TUG flap microvascular breast reconstruction is an excellent option for patients who desire autologous reconstruction and who do not have adequate abdominal donor tissue or who do not desire abdominal scars.

            Use of the transverse upper gracilis (TUG) myocutaneous flap for breast reconstruction was first described as a single breast reconstructive case in 1992 (3).  The cutaneous territory of the gracilis myocutaneous flap was demonstrated by anatomic and injection studies to lie perpendicular to the muscle in its proximal third, transverse and parallel to the medial groin crease.  Based on the direction of exit of cutaneous perforators in the superomedial thigh region, the transverse cutaneous skin paddle of the gracilis muscle has since been accepted as dominant, much like the lower transverse paddle of the rectus abdominis muscle (3).  Perforators extending through the gracilis muscle vascularize the area reaching from over the adductor magnus and sartorius muscle anteriorly to the midline of the thigh posteriorly (4).  
            Although the vertical paddle of the gracilis has been used for breast reconstruction (5), it is accepted as much less reliable (6), and has a more visible vertical scar.  We now offer inner thigh free flap reconstruction using the transverse skin paddle to patients without adequate abdominal donor tissue and to those patients that do not wish to have postoperative scars associated with abdominal tissue harvest. 
            The transverse upper gracilis flap technique is relatively straightforward, reliable and can be aesthetically superior to abdominal reconstruction in two significant ways:  1) it has the advantage of allowing for immediate nipple-areolar reconstruction, negating the need for secondary surgery and 2) coning of the flap into a projecting breast shape is simpler than for abdominal flaps.  By using a semi-lunar construction of the skin paddle, this flap provides excellent dimensions, good projection and can be contoured for immediate nipple areola reconstruction.  The aesthetics of this type of reconstruction can be excellent.
Transverse Upper Gracilis Flap Design
            The TUG flap is designed with a semi-lunar skin paddle transverse to the longitudinal axis of the gracilis muscle in the inner thigh (Figure 1)  The superior aspect of the flap is marked approximately one centimeter below the groin crease anteriorly and centrally, but extends well into the gluteal crease at the most posterior aspect.  Placement of the incision slightly below the crease avoids distortion of the labia majora with related symptoms, as can occur in medial thigh lift (7). 
            The anteroposterior length of the flap extends up to 28 centimeters.  The width of the flap is judged by pinching the inner thigh tissue with the thighs in adduction, using the maximum width that can be easily closed without tension.  The flap has been designed it as wide as 11 centimeters at the central axis over the gracilis muscle (Figure 6).  A pencil Doppler probe is used to confirm the location of perforating vessel(s) over the gracilis muscle and into the skin paddle (Figure 7). 
            The procedure is performed with the patient in the supine position, with the thigh abducted and the knee flexed.  The flap is harvested with the patient in well padded OB-GYN operative stirrups, which facilitates dissection and closure of the posterior aspect of the wound. 
            The anterior thigh incisions are made first.  The posterior branch of the saphenous vein is harvested with the flap (Figure 2), and any anterior venous branches are left in situ although they can be included in the skin paddle if needed.  Lymph nodes are avoided and are left in situ to avoid the risk of lower extremity lymphedema.

            Anterior flap dissection proceeds superficial to the muscular fascia until the medial/posterior edge of the adductor longus is encountered (Figure 3).  Beveling of subcutaneous adipose tissue is used to maximize the bulk taken with the flap.  The deep fascia is incised longitudinally and the space between the adductor longus and gracilis muscle is separated and the vascular pedicle to the gracilis is identified.  Pedicle dissection proceeds proximally to the origin from the superficial femoral artery.  Posterior dissection then continues superficial to the muscular fascia, entering the deep fascia at the posterior aspect of the gracilis.  Pedicle length ranges from 6 to 8 cm.

            The gracilis muscle is transected superiorly and inferiorly, commonly taking only a portion of muscle lying directly beneath the flap (Figure 4).  Additional inferior muscle length may be optionally included for enhanced flap volume.  Usual flap elevation time is approximately 45 minutes or less.

            Following pedicle division, absorbable sutures are used to maintain flap coning and achieve projection (Figures 5 and 8).  The gracilis muscle may additionally be used to increase projection by securing it posteriorly behind the adipose tissue, with predictable postoperative muscle atrophy.  In immediate reconstructions, the mastectomy specimen is weighed and measured for comparison with the TUG flap, typically an appropriate match in terms of volume and dimensions.  Flap projection has often been greater than the native mastectomy specimen (Figure 9).

            The flap is deepithelialized except for an areolar circle in immediate reconstructions (Figure 9d and Figure 10), and completely deepithelialized in nipple-sparing mastectomy.  An areolar circle is created and accentuated by a circumareolar incision for delayed reconstructions, deepithelializing and burying of the superior flap beneath the native mastectomy skin (Figure 11).

            Microvascular anastomosis is usually to the internal mammary system beneath the third or fourth costal cartilage.  Following coning, the pedicle enters the undersurface at the center of the flap, enabling inset of the flap in any orientation desired (Figure 12).  Postoperative flap assessment includes clinical and external pencil Doppler monitoring if the flap is exposed, in addition to continuous implantable venous Doppler probe monitoring.

            The inner thigh donor area is closed with interrupted sutures in the deep fascia (7), interrupted deep dermal and continuous subcuticular skin sutures over a suction drain exiting from the superior aspect of the thigh wound.

            Immediate nipple-areolar reconstruction is performed by folding the semilunar flap and accentuating the apex of the resultant standing cone as the area of maximum projection using interrupted horizontal mattress sutures (Figure 10).  Care is taken not to create excessive suture tension to avoid circulatory compromise to the nipple reconstruction.  An areola circle is drawn, and skin surrounding this circle is deepithelialized and buried beneath the mastectomy flaps prior to microvascular anastomosis.  The naturally darker pigment of inner thigh defines the areolar reconstruction. 
            Patients are placed on post-operative aspirin as an anticoagulant for one month and allowed to ambulate at two to three days postoperatively.  Hospital stay averages five to seven days.

            Autologous abdominal soft tissue reconstruction after mastectomy, although becoming more common, comprised less than a quarter of breast reconstructions performed in the United States in 2008 (8).  The deep inferior epigastric perforator (DIEP) free flap was performed in only 7.5% of reconstructions in that year. 
            The reason for the relative scarcity of soft tissue reconstructions relative to implant reconstructions is not clear; however the complexity of microsurgical reconstruction and the technical difficulty of perforator flap harvest may contribute to the lack of widespread acceptance.  Many patients do not need or desire abdominoplasty at the same time as having a breast reconstruction.  As such, the potential aesthetic perk (9) of abdominal perforator flap harvest may be considered a drawback.  In addition, abdominal flap scars are not insignificant, including the umbilical scar which is visible in currently fashionable low-cut jeans and swim suit bottoms.
            Advantages of gracilis muscle as a microvascular transplant include low donor-site morbidity, a concealed donor scar, constant anatomy with large-diameter vessels, and the potential for a neurosensory flap as well as a large skin paddle.  Anatomic studies (3, 6) have revealed the angiosome of the upper gracilis muscle to lie at right angles to the muscle, in a transverse direction.  As such, the generous size of the transverse skin island that can be harvested with the gracilis allows for shaping of the flap in a circular and cone-like fashion, more closely mimicking natural breast anatomy than the relatively flat projection of abdominal flaps (10).  The inner thigh flap also avoids the relatively visible scar on the lower abdomen together with a numb area below the umbilicus, sequelae of abdominal perforator flaps (11).  The quality of inner thigh tissue is soft and similar to abdominal flaps and breast tissue, unlike the firm, fibrous and stiffer texture of buttock flaps.  Some patients' body habitus clearly favors the inner thigh flap over abdominal flaps, based on their natural depostion of adipose tissue (Figure 13). 
            The conical apex at the central portion of the folded inner thigh flap constructs nipple projection using subdermal fixation sutures at the time of reconstruction.  The resulting nipple areola in our opinion can be aesthetically superior to those reconstructed with local flaps or skin grafts.  Inner thigh skin naturally has slightly darker pigmentation than the skin of the chest or torso, and when contracted and allowed to pucker slightly it can appear even darker.  This color difference with breast skin allows for a natural areolar reconstruction that can be later augmented using medical tattooing if desired (Figures 14 and 15). 
            Early reports of the TUG flap described coverage of defects in the head and neck, lower extremity and thoracic region (12).  Schoeller (13) described a ‘medial thigh lift free flap’ for bilateral autologous breast augmentation after bariatric surgery.  Arnez (14) reported 7 immediate TUG flap breast reconstructions, for ‘small’ or ‘moderate’-sized breasts with sufficient medial thigh tissue, who declined scars in other donor sites.  Wechselberger and Schoeller (15) performed 12 TUG flaps in 10 patients for immediate breast reconstruction.  Fansa (16) reported 32 flaps and Scheoller (11) published a large series of 154 flaps for breast reconstruction in immediate and delayed settings for breast reconstruction, without immediate nipple-areolar reconstruction.  For bilateral reconstructions, the transverse gracilis flap has been suggested to surpass the DIEP flap because of a better concealed donor scar and easier harvest (11).  We have also recently submitted our early data for publication (12). 

Inner Thigh Flap Donor Site          
            Although other autologous tissue reconstruction options are available to patients with previous abdominal tissue harvest or in very thin patients (18), in many of these patients, the inner thigh flap can be used.  Unlike loss of the rectus abdominis muscle, loss of the gracilis muscle is not associated with the risk of abdominal hernias, bulging or functional donor site complications.  The greatest drawback of the inner thigh flap is the inner thigh scar; yet its location near the groin crease is readily concealable in all clothing except swim suits or underwear (19) (Figure 16).

            Tissue expanders and breast implants, latissimus muscle flaps with implants, the inferior gluteal artery free flap, and superior gluteal artery free flap have all been well described as alternatives to abdominal flaps, and the inner thigh flap presents an additional option to these choices.  It is inherent that all autologous soft tissue reconstructions require creation of a donor site and donor area scarring, to some degree.  Certainly, wound complications at the inner thigh donor site necessitating dressing changes are an annoyance for patients as are seromas, and although frequent, this complication is relatively minor.  Patients receive preoperative counseling and full informed consent about this possibility.  In all cases, our patients have been quite satisfied with the final results of their TUG flap reconstructions. 

Gracilis Perforator Flaps
            The inner thigh skin can be harvested as a perforator flap based on the vascular pedicle to the gracilis muscle (19-22).  However, donor site hernia and functional loss are not accepted complications of gracilis muscle flap harvest and are not compelling indications to spare the gracilis muscle.  Despite reports of successful transfer of gracilis perforator flaps, inclusion of the gracilis muscle in the TUG flap has been suggested to potentially provide more tissue volume, to increase safety of monitoring the skin paddle, and to allow rapid harvest with minimal functional donor site morbidity (15).  Anatomic studies of the proximal cutaneous perforator vessels of the gracilis muscle (23) suggest that it is safer to include the gracilis muscle for transfer of tissue in the TUG flap distribution. 
            Gracilis perforator flaps are smaller than the dimensions available for TUG flaps, unless an extended dissection including some gracilis muscle is performed (22).  These authors do not support a clear clinical advantage of preserving the gracilis muscle.  The clinical indication and advantage of the perforator flap is therefore a thin and pliable flap (22), perhaps better suited to extremity coverage.  Although safe applicability of gracilis perforator flaps have been demonstrated, the required longer and more tedious dissection should be weighed against the rapid, easy and routine dissection of a more bulky musculocutaneous gracilis flap. 
            Gracilis perforator dissection would potentially spare loss of donor muscle in the thigh, but functional advantages are not clear, and there may be increased risk to flap circulation as well as increased operating time.  Inclusion of gracilis muscle in TUG flap is suggested to provide more tissue volume, increase safety and allow rapid flap harvest with minimal functional donor site morbidity (23).  In addition, the gracilis muscle does add some bulk to the reconstruction, an advantage in patients with minimal thigh subcutaneous fat.  Certainly, harvesting this flap as a perforator flap is an option, but one that we do not currently see as advantageous. 
             It has been recommended that the saphenous cutaneous venous system be harvested with the perforator flap to enhance venous drainage (19), but we have only required the saphenous system for venous outflow in one patient that had poor internal mammary drainage.  This outflow may have been helpful in our other patient that developed some delayed venous insufficiency.  Nevertheless, saphenectomy can be a cause of morbidity (24) while the need for secondary venous drainage in this series has been rare. 

            The transverse upper gracilis flap can be used for microsurgical breast reconstruction in patients with previous abdominoplasty, inadequate abdominal tissue, or in patients that object to abdominal or buttock scars.  The inner thigh flap offers an autogenous tissue reconstructive option after mastectomy with excellent projection, the potential for immediate nipple-areolar complex reconstruction, and a favorable donor scar position and quality. 
            The TUG flap has significant advantages in addition to its pleasing final reconstructive appearance.  The gracilis muscle pedicle and harvest are extremely reliable and straightforward, and are familiar to most Microsurgeons.  No intraoperative repositioning is required as often for flaps from the buttocks or back, and a two-team approach is facilitated by dissection of the contralateral thigh during mastectomy.  Since TUG flap design allows immediate nipple areola reconstruction, the need for tattooing, local flaps or skin grafting may be obviated.  In some patients, the medial thigh lift may be considered an aesthetic perk of this procedure.  The inner thigh flap has become a favorite in our armamentarium of microvascular breast reconstruction choices. 
            Candidates for the inner thigh gracilis flap include patients desiring autologous breast reconstruction; those with sufficient superomedial thigh tissue; previous abdominoplasty or DIEP, SIEA or TRAM flap harvest; previous abdominal surgery precluding use of abdominal tissue for reconstruction; or very thin or athletic patients without sufficient abdominal or buttock donor tissue.

References (see full publication - to be posted)