Muscle-Sparing and Free TRAM Flap Breast Reconstruction

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CHAPTER 8 Muscle-Sparing and Free TRAM Flap Breast Reconstruction

Joseph J. Disa, Andrea L. Pusic, Toni Zhong

Summary/Key Points

1. The choice of which technique of transverse rectus abdominis myocutaneous (TRAM) flap to use is based on the physical characteristics of the patient as assessed both preoperatively and intraoperatively. The physical examination is generally most helpful in arriving at the decision between a pedicled or a free TRAM flap preoperatively, while the decision to use a free TRAM or muscle-sparing (MS) TRAM or deep inferior epigastric artery perforator (DIEP) flap is made intraoperatively based on individual anatomical variations.

2. For most breast shapes, a contralateral free or MS TRAM anastomosed to the internal mammary vessels or an ipsilateral free or MS TRAM anastomosed to the thoracodorsal vessels allows for a vertical flap inset, which best recreates the naturally ptotic appearing breast.

3. Before committing to free muscle transfer by transection of the superior aspect of rectus muscle, the recipient vessels must be completely dissected to ensure usability of both the vein and artery.

4. When performing a muscle-sparing TRAM, the medial anterior rectus sheath incision is made first and intramuscular dissection is carried inferiorly while visualizing the medial branch of the pedicle to ensure that it is retained with the flap. The superior border of the anterior rectus sheath incision is then made and the muscle is transected. At this point, the underside of the rectus muscle is inspected to directly visualize both the medial and lateral branches of the deep inferior epigastric vessels. This way, the lateral fascial incision can be safely made at a location lateral to the lateral branch of the pedicle such that both branches of the pedicle are harvested with the flap.

5. When insetting the TRAM flap, the first tacking suture is placed at the most superomedial position followed by the placement of tacking sutures along the sternal border and then superior border of the mastectomy space to ensure adequate superomedial volume of the reconstructed breast. Superolaterally, the TRAM flap is tacked to the remaining soft tissue anterior to the axillary fold to avoid an unsightly dysjunction between the axilla and breast. Proper positioning and shaping of the flap at the initial stage is the key to obtaining optimal breast aesthetics and minimizing the need for future revisions.

Introduction

Breast reconstruction with autologous tissue can generally achieve more durable and natural results than with the use of implants alone.¹ When well designed and executed, the TRAM flap offers the advantage of being able to provide large soft tissue volume. In large breasted women undergoing unilateral reconstruction, this technique offers improved aesthetics over implant reconstruction (Fig. 8.1). In addition, complete restoration of the breast mound is often possible in a single stage. Of all the available donor sites for autologous breast reconstruction, the TRAM flap in both pedicled and free form is the most frequently used method.² The evolution of the TRAM flap, from pedicled, to free TRAM, to muscle-sparing (MS) free TRAM, to perforator flap (DIEP) has occurred in an attempt to reduce the morbidity that results from the loss of the rectus muscle and anterior sheath associated with the pedicled TRAM flap.

Fig. 8.1 Postoperative photos of a large breasted patient who has undergone left sided mastectomy with immediate reconstruction using a MS-TRAM. Note the large soft tissue volume of reconstruction on the left side to match the native breast. A Frontal view. B Right oblique view. C Left oblique view.

The free TRAM flap is based upon the dominant deep inferior epigastric vascular pedicle which permits transfer of a larger volume of abdominal tissue than with the use of pedicled TRAM flaps. The muscle-sparing TRAM flap is a modification of the free TRAM flap which limits the amount of rectus muscle and anterior sheath harvested to only those encompassing the medial and lateral rows of musculocutaneous perforating vessels. The theoretical advantage of the muscle-sparing TRAM is the ability to minimize the violation of the abdominal wall integrity while ensuring equal blood supply to the flap as compared to a free TRAM flap. A more comprehensive understanding of the evolution of the MS TRAM to the DIEP flap is reflected in the classification of muscle-sparing TRAM described by Nahabedien ³ (Table 8.1). The DIEP flap is the most refined form of MS TRAM in which no muscle or anterior rectus fascia is harvested with the abdominal flap.

Table 8.1 Classification of MS free TRAM

Muscle-sparing technique	Definition (rectus abdominis)
MS0	Full width, partial length harvested
MS1	Preservation of lateral segment
MS2	Preservation of medial and lateral segments
MS3 (DIEP)	Preservation of entire muscle

From Nahabedian MY, Momen B, Galdino G, Manson PN. Breast reconstruction with the free TRAM or DIEP flap: patient selection, choice of flap, and outcome. Plast Reconstr Surg 2002;110(2):466.

Indications and Contraindications

Indications

A free or MS TRAM represents an excellent reconstructive option for women undergoing either immediate or delayed breast reconstruction who possess an adequate amount of abdominal fat to achieve the desired breast volume. Moreover, free TRAM or MS TRAM flaps are preferred over pedicled TRAM flaps in the immediate breast reconstruction setting because there is less risk of fat necrosis or partial flap loss in the breast flap. The more dominant blood supply to the free TRAM or MS TRAM can help minimize the problems with wound healing that can lead to delays in the delivery of adjuvant therapy as seen with pedicled TRAMs.⁴ While obesity and tobacco smoking are two relative contraindications to performing a pedicled TRAM flap, in these high risk patients who either require or strongly desire autologous tissue reconstruction, they generally have a lower complication rate in both the breast and abdomen following a free TRAM or MS TRAM flap.²^,⁴ This is felt to be due to a more robust blood supply to the breast and less surgical insult to the abdominal wall integrity. Lastly, in a large-breasted patient who does not desire a reduction on the contralateral side, a free TRAM or MS TRAM will more reliably transfer a large amount of abdominal tissue onto the chest wall than a pedicled TRAM flap (Box 8.1).

Contraindications

Absolute contraindications to free TRAM or MS TRAM include:

1. Any previous abdominal surgeries that may have transected the inferior epigastric blood supply to the flap.

2. Previous abdominal surgeries that have disrupted the system of periumbilical perforators to the cutaneous portion of the TRAM flap.

3. Lack of recipient vessel availability.

4. Lack of redundant lower abdominal tissue.

Abdominal incisions that should arouse suspicion include those used for inguinal hernia repair and paramedian scars. Conversely, common scars that generally do not preclude the use of free TRAM flaps are lower transverse incisions such as a Pfannensteil incision or midline incisions. The potential lack of recipient vessels should be suspected in patients with both a heavily dissected axilla and radiation to both the chest wall and axilla. Other relative contraindications to free TRAM flaps include patients who are medically unfit, patients with a grave prognosis, and previous liposuction to the abdomen (Box 8.1).

Patient Selection

The choice of which technique of TRAM flap to use is based on the physical characteristics of the patient assessed both preoperative and intraoperatively. An algorithm to aid the decision-making process is outlined in Figure 8.2. Generally, whether the patient is a good candidate for pedicled versus free TRAM can be determined preoperatively based on the physical examination. On the other hand, the decision to use a free TRAM or MS TRAM or DIEP flap is made intraoperatively based on individual anatomical variations.

Fig. 8.2 Algorithm for procedure and patient selection.

The role of rectus abdominis muscle within the abdominal flap is to carry and protect the epigastric vascular system.⁵ The muscle itself is not felt to contribute to volume, shape, or vascularity of the reconstructed breast. MS TRAM minimizes the amount of rectus abdominis muscle and anterior rectus sheath harvested, and thus lessens the insult to the abdominal wall. Though comparative studies examining the incidence of hernias and bulges following pedicled TRAM, free TRAM, and DIEP flaps have shown mixed results, evaluations of abdominal strength have demonstrated that free TRAM is superior to pedicled TRAM, and DIEP flap may be further superior to the free TRAM.⁶^–⁹ More recently, Nahabedian et al observed a significantly higher incidence of lower abdominal bulges in bilateral breast reconstruction in the non-muscle-sparing than muscle-sparing group.⁵

The patient characteristics noted preoperatively are as follows:

1. Breast size and volume. When the desired reconstructed breast volume is in excess of 1000 g, then free TRAM or MS TRAM flap is the technique of choice. Pedicled TRAM flaps are most reliable when the transferred abdominal flap is small in volume and based largely around Zones I and II. Although DIEP flaps based on one or two perforators have been demonstrated to provide adequate perfusion, its usefulness for large volume reconstructions has not been rigorously established.³

2. Abdominal pannus. While a small to moderate pannus is ideal for a pedicled TRAM flap, a pannus that is any larger harbors significant risk for wound partial flap loss and significant fat necrosis in the breast.⁴ Free TRAM or MS TRAM can more safely address this issue because the blood supply is based on the more dominant deep inferior epigastric pedicle.

3. Smokers. Although TRAM reconstructions are strongly discouraged in active smokers, free TRAM or MS TRAM is preferred over pedicled TRAM flaps in those who require or strongly request autologous breast reconstruction. The free TRAM flap captures more periumbilical perforators and minimizes the morbidity related to tobacco use in both the breast and abdomen.

The anatomical flap characteristics noted intraoperatively are as follows:

The decision between performing a MS TRAM versus DIEP is made at the level of the anterior rectus sheath.

1. Caliber of perforators to the skin. Most authorities in this field agree that if an arterial perforator is greater than 1.5 mm in diameter with a palpable pulse and a visible vein, then a DIEP flap can be attempted safely.^3,^7,¹⁰ If none of the aforementioned criteria are met, then a MS-TRAM is preferred.

2. Number of perforators to the skin. In some patients, there are a large number of perforators in both the medial and lateral rows, but no single dominant perforator. In these patients, a MS-TRAM is preferred over a DIEP flap. The average number of medial and lateral row perforators encountered in a free TRAM is usually three to four per row.¹¹

3. Location of perforators to the skin. If two dominant perforators equal in caliber are present and are located adjacent to each other within the same row (i.e., both are in the medial row or both are in the lateral row), then the possibility of performing a DIEP flap based on both perforators is explored. If two dominant perforators equal in caliber are present but are located either in different rows or far apart from each other, then the decision between using a MS TRAM or a DIEP flap is based on the caliber of the perforators. If both perforators are less than 1.5 mm, then a MS TRAM is performed. A DIEP flap is attempted if the perforators are greater than 1.5 mm in diameter. In the latter scenario, the DIEP flap will be based on the perforator that is most caudal, such that the length of intramuscular dissection of the perforator to the main pedicle is minimized.

Operative Technique

Marking

The patient is marked in an upright as well as supine position.

Breast marking

The inframammary line is an important landmark to be noted preoperatively. In the immediate reconstruction setting, the marked or stapled inframammary line is a helpful guide to define the lower limit of the mastectomy for the breast surgeon. In the delayed setting, the previous inframammary line is determined from the opposite breast and reproduced on the ipsilateral side.

For a patient undergoing skin-sparing mastectomy with a small or moderate sized breast, a simple elliptical or circular excision is marked over the central mound of the breast which includes the nipple–areolar complex (NAC). This allows closure of the reconstructed TRAM flap skin to the mastectomy skin either in an elliptical pattern or as a circular purse-string pattern to create a template for the future NAC (Figs 8.3 and 8.4). For a patient with large breasts or breasts with grade III ptosis, a Wise type pattern skin reduction can be used in the involved breast (Fig. 8.5). For patients with existing grade II ptosis in the involved breast who wish a future mastopexy on the opposite breast, a vertical mastopexy skin excision pattern can be applied.

Fig. 8.3 A Preoperative photo. B Postoperative photo following skin-sparing mastectomy with elliptical pattern and MS TRAM reconstruction.

Fig. 8.4 A Preoperative photo. B Postoperative photo following skin-sparing mastectomy with periareolar circular pattern and MS TRAM reconstruction.

Fig. 8.5 A Preoperative photo showing left breast following a lumpectomy. B Postoperative photo showing left sided mastectomy using a Wise pattern reduction with MS TRAM reconstruction. A nipple areolar reconstruction has been performed on the left breast mound. Wise pattern reduction was performed on the right breast.

Abdominal marking

The transverse skin island of the TRAM flap is marked over the lower abdomen encompassing the lower abdominal redundant soft tissues. The superior incision lies just above the level of the umbilicus in order to capture as many periumbilical perforators as possible into the flap (Fig. 8.6). Ideally, the height of the abdominal flap should be equal or greater than the breast width of the mastectomy specimen (Fig. 8.7). This is because during the flap inset, the TRAM flap is inset vertically on the chest as to create the most natural ptotic shape for the reconstructed breast. In designing the inferior incision, care is taken to mark it at a location such that the abdomen can be closed with minimal tension. As well, the inferior incision is designed such that it is hidden in the natural suprapubic crease to camouflage its appearance. Lastly, the inferior incision should not be within the pubic hair-bearing region, as this may lead to problems with delayed wound healing. A midline mark is made just above the umbilicus and on the pubic region. These marks help place the midline of the upper abdominal flap to the midline of the pubic area when closing the abdominal donor site.