Gracilis, Tensor Fascia Lata, Vastus Lateralis, Rectus Femoris, and Gluteus Maximus Flaps




BACKGROUND



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The introduction of radical vulvar surgery and pelvic exenteration in 1950s allowed for the treatment of locally advanced or recurrent cancer with improved survival outcomes.1,2 Unfortunately, the large defects accompanying radical vulvar surgery were often complicated by significant infections and poor wound healing. In light of the significant risk of postoperative morbidity, the quality of life following radical surgery has been of great concern to both patients and surgeons. To improve these outcomes, advances in reconstructive procedures have evolved to provide coverage of defects, enhance cosmetic results, and preserve quality of life.3



A thorough understanding of anatomy and surgical technique is a prerequisite for reconstruction of surgical defects of the vulva and pelvic floor. When selecting the appropriate closure technique, the simplest method is usually preferred. In many cases, extensive prior treatment (eg, radiation therapy), will make primary closure impractical and require the use of myocutaneous flaps for reconstruction of the pelvic floor. The use of myocutaneous flaps has become more popular over the past several decades and may include (1) transposition flaps, which pass over a portion of normal tissue to reach the defect, (2) rotational flaps, which are turned on an arc onto the defect, and (3) advancement flaps, which are moved onto the defect along a straight axis. Myocutaneous flaps are defined by the musculature, but also include the skin, subcutaneous tissue, and fascia and receive their blood supply from a predominant subcutaneous artery. The overlying skin typically receives its blood supply from perforators coming off the axial vessels within the muscle. Appropriate flap design allows for the placement of healthy, well-vascularized tissue into a surgical defect achieving the elimination of “dead-space” and defect closure.



Although reconstruction of the pelvic floor was introduced in the nineteenth century for congenital absence of the vagina, advances in surgical understanding and techniques have led to improved outcomes. Since the 1970s, the use of myocutaneous flaps derived from the upper portion of the lower extremity have been described for reconstructive purposes. Initially, pelvic defects resulting from radical vulvovaginal surgery were repaired in a 2-step process or left to heal by secondary intention. However, over the last 2 decades, immediate reconstruction of pelvic floor defects has become the standard and resulted in favorable outcomes.4,5 Once a decision has been made to perform reconstructive surgery, the selection of the specific procedure should be based on the principles of restoring normal anatomy, optimizing function, and minimizing the risk of postoperative morbidity. Patients and providers need to be aware of the affect of reconstructive surgery on both the transfer site and the donor site.



Vulvovaginal reconstruction following radical extirpative surgery results in superior outcomes in quality of life measures, particularly sexual function. Furthermore, when compared with patients who have not undergone reconstructive surgery, those who have undergone reconstruction have shown reduced complications such as infection and fistula formation.6 As a result, pelvic floor reconstruction should be seriously considered as a means to reduce perioperative morbidity and enhance would healing even if the patient does not desire preservation of sexual function.6



Preoperative preparation for vaginal or vulvar reconstruction requires thorough surgical planning as well as extensive counseling of the patient and her caregivers. The patients should be made aware of the goals of reconstruction and understand the requirements for successful convalescence, which may include prolonged bed rest or limited mobility. The potential effects of reconstructive surgery on sexual health and possible need for rehabilitative services should be specifically delineated. Identifying patients at high risk for vascular compromise of the flap pedicle, such as heavy smokers, diabetics and obese patients, is a priority. For example, smokers should be advised to discontinue smoking at least 3 weeks prior to operation. Similarly, diabetes control should be optimized preoperatively and maintained throughout the postoperative period.



In addition to basic preoperative considerations, such as anesthesia consultation and reservation of a critical care bed, meticulous deliberation regarding the impact of the procedure on both the transfer and the donor sites is required. The size, shape, and thickness of the defect to be covered are all important factors that must be taken into account. For example, situations where the subcutaneous component of the flap may limit or preclude creation of a neovagina, such as with morbid obesity, the muscle alone with a skin graft may be used safely. A careful review of relevant previous surgeries is critical to appropriate flap selection and may identify vascular pedicles that could be compromised. If there is a concern for the patency of the flap vasculature, then evaluation with preoperative angiography should be performed. A detailed review of prior radiation treatment records is always warranted so that flaps can be selected from outside of irradiated fields (eg, lower extremity), which may result in better neovascularization of the flap.5 If postoperative radiation is anticipated, then the flap transfer site may also be impacted.



This chapter provides an overview of myocutaneous flaps derived from the posterior trunk and the upper portion of the lower extremity. Specific flaps along with anatomic landmarks are listed in Table 18-1, and an overview of the relevant surgical anatomy of the anterior and lateral thigh is shown in Figure 18-1.




Table 18-1.Reconstructive flaps for vulvovaginal and inguinal defects.




Fig. 18-1.


Surgical anatomy for myocutaneous flaps from the anterior and lateral thigh.






GRACILIS FLAP



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Indications and Clinical Applications



The gracilis muscle flap was first described in 1976 and is one of more common flaps used for reconstruction of the vagina and/or vulva.7 The flap is quite versatile and can be used for partial or total vaginal reconstruction, suprapubic wound closure, and anal sphincter reconstruction.6,7,8,9,10 The gracilis flap is a useful alternative for pelvic floor reconstruction when a rectus abdominus flap is not an option because of concurrent abdominal stoma placement accompanying exenterative surgery.



Anatomic Considerations



The gracilis muscle originates from the pubic symphysis, inserts on the medial tibial condyle, and functions as a thigh adductor. It is a thin, flat muscle that lies between the adductor longus and sartorius muscles anteriorly and the semimembranosus muscle posteriorly. Due to the presence of the abductor longus and magnus muscles, the gracilis muscle is expendable from a functional standpoint. The dominant blood supply to the gracilis flap arises from the ascending branches of the medial circumflex femoral vessels. This vascular pedicle is typically 6 cm in length and enters the gracilis muscle approximately 8 to 10 cm below the muscle origin. Additional branches of the femoral vessels also supply the muscle and enter the distal third of the muscle belly. The overlying skin is supplied by perforating vessels from the gracilis muscle.



The gracilis myocutaneous flap can be designed with either a vertically or transversely oriented skin island. The standard vertical skin island design is centered over the proximal third of the gracilis muscle with average dimensions of 8 cm in width and 15 cm in length. The transverse skin island may extend beyond the muscle edges for 4 to 5 cm and should be centered over the proximal third of the muscle. The transverse skin island can accommodate dimensions of 20 cm in width and 6 cm in length. Although the muscle has an excellent and predictable blood supply, the distal aspect of a longitudinally oriented skin paddle can be variable. In patients who are obese, the thickness of the skin paddle may limit flap mobility or result in constriction of the vascular supply. In such circumstances, a gracilis muscle-only flap combined with a skin graft may be a more prudent choice that the full-thickness myocutaneous flap.



Preoperative Preparation



Box 18-1 KEY SURGICAL INSTRUMENTATION




  • Bipolar, jeweler forceps (coated): Fine-tipped forceps to allow for manipulation of the vascular adventitia without risking traumatic injury during vessel dissection



  • Dissecting scissors (eg, Reynolds tenotomy): Fine-tipped dissecting scissors to allow for vascular dissection if increased pedicle length is desirable prior to flap transposition



  • Microvascular clips (automatic or manual applier): Hemostatic clips during flap dissection



  • Weitlaner retractors (medium, sharp): Self-retaining retractors during pedicle dissection



  • Richardson retractors: Wide, right-angled retractor to facilitate flap and vascular exposure




As a thin, pliable muscle, the gracilis muscle is used for reconstruction of small-to moderate-sized defects involving the skin, soft tissue, bone and the pelvic floor. Preoperative consideration must be given to the following: need for unilateral or bilateral flaps, whether skin is to be included, and whether the skin paddle will need to be oriented transversely or longitudinally over the muscle. The operative goals with respect to elimination of “dead space,” cosmesis, and amount of skin required will be the primary drivers for the type of gracilis flap designed.



The flap can be elevated as either a muscle-only or a myocutaneous flap. Preoperative markings should be made while the patient is standing and able to contract the muscle allowing for a more accurate orientation of the skin paddle (Figure 18-2). Placing the patient in the supine or lithotomy position with the hips abducted (45 degrees) allows for the muscle to easily palpated (Figure 18-3).6 However, this position may lead to anterior displacement of the skin paddle relative to the underlying muscle. With this shift of the overlying skin inferior to the muscle, the true skin paddle lies posterior to the muscle belly. Understanding this dynamic is important to limit the potential for skin devascularization.




Fig. 18-2.


Gracilis flap skin paddle design with the patient in the standing position.






Fig. 18-3.


Gracilis flap skin paddle design with the patient in ­dorsal lithotomy position.





To mark the site, a line is drawn from the pubic tubercle, at the adductor longus tendon insertion, to the medial condyle of the femur. A second line is drawn 2 to 3 cm posterior to this original marking and represents the surface marking of the longitudinal axis of the muscle. The terminal branches of the medial circumflex femoral vessels enter the posteromedial surface of the muscle approximately 8 to 10 cm below the pubic tubercle. If a muscle-only flap is required, then an incision can be made overlying the belly of the muscle as represented by the surface skin marking. For a myocutaneous flap, the skin paddle can be oriented either transversely or longitudinally over the muscle. A 15 × 8 cm vertical skin paddle can be designed, centered over the proximal third of the inner thigh. The distance between the skin bridge from the introitus to the apex of the incision should be 6 to 8 cm.6 The distal aspect of this skin paddle can have variable vascularity and must be designed with caution. A transverse skin paddle is generally more reliable and can be designed to measure 20 × 6 cm. Although more reliable, a transverse skin paddle limits the arc of rotation.



Surgical Procedure



Box 18-2 MASTER SURGEON’S PRINCIPLES




  • Predetermination of the size and shape of the flap to fit the defect is imperative.



  • Patient positioning should be comparable to the postoperative position so that tension is not increased across the flap.



  • Obese patients (body mass index [BMI] > 35 kg/m2) may present a challenge due to a variable blood supply to the skin and decreased mobility of the flap.




The muscle-only flap can be elevated by making the skin incision along the surface marking of the longitudinal axis of the muscle. The muscle can be easily identified posterior to the adductor longus muscle. If a skin paddle is required, then it must be centered over the proximal one-third of the muscle, as this is where the cutaneous perforating vessels are primarily located. To ensure appropriate design of the skin paddle, the distal aspect of the muscle at its musculotendinous insertion is identified as the first step to muscle elevation by making a 3-to 4-cm transverse incision over the palpable gracilis tendon on the distal medial thigh. A long Kelly clamp is inserted beneath the tendinous insertion and used to place the gracilis muscle belly on traction to precisely define its location. If necessary, the skin paddle can be reoriented at this time to more closely approximate the course of the muscle belly. In developing the skin paddle, the subcutaneous tissue dissection should be beveled outward for 1 to 2 cm in order to maximize the cutaneous perforating vessels included with the flap. The incisions are then carried down through the deep muscular fascia until the anterior and posterior edges of the muscle have been identified. A layer of fascia should be left on the muscle, as this may also include vessels to the overlying skin paddle. The skin paddle should be anchored to the underlying muscle to prevent shearing forces from disrupting small perforating vessels as the flap is manipulated. The muscle is raised working in a distal to proximal direction, and the minor pedicles from the superficial femoral vessels should be ligated after the more proximal dominant primary pedicle is identified. The main vascular pedicle to the gracilis flap is identified by retracting the adductor longus muscle medially at a point approximately 10 cm below the pubic tubercle. If necessary, the muscle can be divided both proximally and distally to increase the arc of rotation. Care should be taken to avoid excessive tension on the vascular pedicle, particularly if the proximal muscle has been divided. More commonly, the proximal muscle is left intact and the distal muscle divided. The skin paddle can be designed as a “skin island” to further improve the arc of rotation into the defect. Incising the proximal fasciocutaneous portion of the flap skin paddle creates an island flap. After the extirpative operation has been completed, a subcutaneous tunnel with a skin bridge is created from the gracilis donor site to the vaginal defect. Once isolated, the flap is brought under the skin bridge with gentle traction (Figure 18-4). If further length is needed to maximize the arc of rotation, then the proximal muscle can be divided, and the flap pedicle can also be lengthened by dissection to its take-off point at the profunda femoris vessels.




Fig. 18-4.


Gracilis muscle flap elevation, rotation, and transposition into the vaginal defect.





A unilateral gracilis flap is usually sufficient for reconstructing a partial vaginal defect. However, reconstructing large or complete vaginal defects or creation of a neovagina will likely require bilateral flaps. For total vaginectomy defects, the flaps are positioned so that the skin surfaces face each other and the skin edges of the flaps are sutured together using an interrupted absorbable suture, such as 3-0 delayed absorbable suture (Figure 18-5). The lateral walls of the remaining vaginal mucosa can be incised for 1 to 2 cm and are allowed to splay open to prevent vaginal stenosis near the entrance of the vagina.11 The distal points of each flap are then inset into these incisions and the edges of the vaginal defect reapproximated using an absorbable suture. For partial vaginectomy defects, the flap is inset and the skin edges of the flap are sutured to the vaginal mucosa circumferentially, using the same suture technique. The neovaginal pouch (sutured gracilis flaps) is then sutured to the periosteum of the pubis to prevent herniation of the neovagina.




Fig. 18-5.


Bilateral gracilis flap neovagina.





In patients who are obese, inclusion of an overlying skin paddle may make the flaps too thick to create a neovaginal vault. In this setting, skin graft placement over the muscle is preferred. The gracilis muscles are passed into the perineal aspect of the vaginal defect and sutured together along their perimeter to create a muscular pouch. Skin grafts can be harvested at 10/1000 thickness with a dermatome from the lateral aspect of the thigh. The skin grafts are then sutured (dermal side out) around a large, soft vaginal stent with absorbable chromic suture. The skin-grafted stent is placed into the muscular pouch, and the pouch and stent are placed into the vaginal defect. The labia majora are sutured together for 7 days to allow for the skin graft to take and to prevent the stent from being extruded out of the neovagina.10



If the gracilis muscle is utilized for “dead space” obliteration along the pelvic floor, then the skin paddle can be de-epithelialized. This technique can be used when a synthetic mesh has been placed for pelvic stability to limit the potential for a mesh-associated complication (eg, erosion).



The donor site is closed primarily. It is generally not ­necessary place a muscle closure layer. Placement of inter-­muscular sutures can lead to myonecrosis and undue tension. Dermal and skin closure is sufficient with appropriate flap design that avoids excessive tension at the closure. Drainage catheters are placed on each side of the subcutaneous perineal tunnel and alongside each gracilis muscle flap. Round, hubless closed suction drains are our preferred drain type. The skin of the gracilis donor site is closed in 2 layers using 3-0 delayed absorbable for the subcuticular layer and a running 3-0 Prolene for reapproximation of the skin. With appropriate skin paddle design that avoids excessive tension, a surface bolster overlying the incision is not necessary.



Postoperative Care



Box 18-3 PERIOPERATIVE MORBIDITY




  • Flaps may be associated with vaginal abscess or cellulitis, which is often amenable to antibiotics and conservative measures.



  • Surgical intervention/revision may be required for flap necrosis and flap prolapse.



  • The flap donor site is at risk for myonecrosis or compartment syndrome and should be inspected each day.




The patient is encouraged to ambulate by the second or third postoperative day. Due to increasing edema and venous congestion of the flap, prolonged sitting should be avoided. The gracilis flap should be inspected daily for both color and capillary refill. When a gracilis flap has been used for vaginal reconstruction, the distal aspect of the flap is easily examined by retracting the labia minora. Examination of the proximal portion of the flap(s) is best performed at the time of examination under anesthesia 7 to 10 days postoperatively. Doppler signals are typically not present in a gracilis flap design and should not be used for flap monitoring. If a muscle-only flap is performed with overlying skin graft placement, then assessment of the perfusion can be difficult. The same parameters for color and capillary refill do not pertain to skin graft placement overlying muscle. Although the muscle can be evaluated for color, this can prove difficult within the reconstructed vaginal vault particularly as the muscle becomes edematous in the postsurgical period.



The most common cause of compromised flap viability is tension on the vascular pedicle. Excessive abduction of the thigh should be avoided. Persistent concern over flap viability may require a return to the operating room for exploration and takedown of the flap transfer site. The vascular pedicle may need further dissection to optimize pedicle length. Consideration should also be given to revising the subcutaneous tunnel, which should be at least 3 times as wide as the width of the muscle (3-4 fingerbreadths) to account for postoperative edema and compression of the muscle/and or vascular pedicle.



Patients and caregivers should be aware that after gracilis flap, vaginal drainage is anticipated due to sloughing of the skin and can often be treated with conservative measures. Judicious use of antibiotics and consideration of drain placement to prevent accumulation of fluid may reduce the incidence of infection or abscess formation.4



Although operative mortality and surgical complications have decreased markedly with improvements in technique, morbidity from gracilis muscle flaps is common.3,7,12 Early complications requiring intervention may occur in up to 50% of patients, and flap loss rates may reach as high as 15%.3,4,13 The most common problems include skin necrosis, which often requires debridement, and vaginal drainage and abscess, which may be a result of skin sloughing and infection.5,6,8,13 Skin separation, dysethesias, hematoma formation, and erythema are also common, but are usually amenable to conservative measures.4,5,13,14



In an effort to reduce the rate of flap complications, a modification of the gracilis flap that utilizes a smaller flap size for neovagina construction has been described and is associated with improved clinical outcomes.13,15,16 The enhanced mobility of the smaller flap design reduces the risk of wound breakdown and necrosis. Anchoring the gracilis flap to the pelvic floor can further reduce tension on the vascular pedicle as well as decrease the risk of flap prolapse.15



Long-Term Outcomes

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Jan 12, 2019 | Posted by in GYNECOLOGY | Comments Off on Gracilis, Tensor Fascia Lata, Vastus Lateralis, Rectus Femoris, and Gluteus Maximus Flaps
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