Both, the pedicled TRAM-flap by Scheflan et al[14] and the free TRAM flap by Holmström[18] have been widely used for autologous breast reconstruction in the past decades. The free TRAM flap is composed of a lower abdominal skin island overlying usually one rectus abdominis muscle (Figure 1). The overlying skin island and its subcutaneous fat tissue is supplied by the perforating vessels from the deep inferior epigastric artery (DIEA) travelling through the muscle. It covers approximately the area typically excised in an aesthetic abdominoplasty procedure. The DIEA is dissected together with a 5-6 cm strip of rectus muscle and anastomosed microscopically to the recipient vessel, which is typically the internal mammary artery (IMA) or, less frequently, the thoracodorsal artery. The fascial defect in the lower abdominal wall is typically repaired with an alloplastic mesh (Figure 2) and the wound is closed similarly to an abdominoplasty incision. Significant donor-site morbidity remained a major concern with this technique and resulted in an effort towards conserving as much muscle as possible[19]. Over time, the free TRAM flap sacrificing the whole muscle evolved into the muscle-sparing (ms-) TRAM flap and in further consequence into the DIEP flap with the main goal to minimize donor-site morbidity by harvesting less muscle and fascia. The ms-TRAM flap, in which only a small cuff of muscle around the vascular pedicle is harvested (Figure 3), is still a widely used method in breast reconstruction as it is technically less challenging than the DIEP flap with a comparable donor site morbidity[20].

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Figure 1 Typical example of a free transverse rectus abdominis muscle-flap showing the undersurface with its vascular pedicle and the completely excised rectus abdominis muscle.

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Figure 2 After harvest of a full transverse rectus abdominis muscle-flap, the fascial defect of the rectus fascia usually has to be closed with a synthetic mesh.

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Figure 3 In a muscle-sparing free transverse rectus abdominis muscle, only a portion of the rectus muscle is included in the flap.

The popularity of the DIEP flap has increased widely over the last decade. Currently it is the gold standard in autologous breast reconstruction not only because of its low donor site morbidity but also because of the satisfying aesthetic outcomes it can achieve. The DIEP flap utilizes the same skin island as the TRAM flap without harvesting the abdominal rectus muscle and anterior rectus sheath. Harvesting DIEP flaps requires considerable expertise in perforator pedicle dissection. Especially during the intramuscular part of the preparation one must dissect carefully to avoid damaging of the perforator vessels, which would subsequently lead to compromised flap circulation[21]. The DIEP flap is generally based on 1-3 perforating vessels and their connection to the DIEA (Figure 4). Unlike the TRAM flap dissection, these perforating vessels are carefully traced through the abdominal rectus muscle to their connection with the DIEA. Prior to surgery, the major perforating vessels can be identified via computed tomographic (CT)-angiography (Figure 5), Doppler ultrasonography or, if available, magnetic resonance imaging-angiography. Preoperative CT-angiography has been shown to reduce operative time, and can help to avoid injuries of the vulnerable pedicle[20]. DIEP flaps are typically outlined similar to aesthetic abdominoplasty procedures and surgical marking takes place in a standing position.

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Figure 4 Example of a deep inferior epigastric perforator-flap with 2 perforators merging into the deep inferior epigastric vessels.

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Figure 5 Computed tomographic-angiography to better elucidate the exact anatomy of perforators of the deep inferior epigastric perforator-vessels. The red arrow points out the piercing of the perforator through the rectus abdominis muscle on the sagittal (left) and transverse (right) view.

Simultaneous raising of the flap and preparation of the recipient vessels typically requires a two team approach. The IMA and vein are also here the preferred recipient vessels, while the thoracodorsal artery and vein remaining second choice. The IMA is typically approached in the second or third intercostal space. In case of a tight rib interspace, a small part of the rib cartilage can be removed for a better insetting of the pedicle.

After the skin incisions are made the superficial inferior epigastric artery (SIEA) and vein are first approached. In case of sufficient size and quality, they can be dissected down to their origin from the common femoral artery and a SIEA flap can be performed (see below). In case of an unsuitable SIEA, the abdominal skin island is raised carefully from lateral to medial until the lateral row of perforators is reached. Vessel diameter is the key factor in selecting a perforator. Once a perforator has been chosen, the anterior rectus fascia is incised and the perforator is dissected through the muscle until sufficient caliber of the pedicle is reached. Additional perforators in the same row may also be dissected out and included for further blood supply. However, intercostal motor nerves supplying the rectus muscle have been shown to enter the muscle just medial to the lateral row perforators and therefore harvesting of the lateral row perforators may decrease abdominal wall stability.

After completion of dissection, the flap is divided from its pedicle and passed to the chest for anastomosis and inset. The recipient vein and the vein of the flap are typically connected under magnification using an anastomotic coupling device. The arterial anastomosis is generally performed with a 9.0 suture. Upon completion of the anastomosis, the flap is checked for capillary refill. Finally, the incision in the anterior rectus fascia is closed directly without the need of a mesh.

DIEP flaps can be used in uni- and bilateral post-mastectomy breast reconstructions (Figure 6) and may also be used for reconstruction of congenital thoracic defects. There are only a few contraindications for the use of a DIEP flap. In the past, absolute contraindications included history of previous abdominoplasty, liposuction, or active smoking. Large transverse or oblique abdominal incisions were regarded as relative contraindications. Today, as a result of technical refinements, the only real absolute contraindications to DIEP flap reconstructions are non-compliant patients and/or a poor general condition. Obesity itself is not a contraindication, although it may lead to less aesthetically pleasing outcomes[22-24].

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Figure 6 Pre- and post-operative pictures of a patient who underwent delayed reconstruction on her right side with a hemi-deep inferior epigastric perforator-flap and immediate reconstruction of her left side with the second hemi-deep inferior epigastric perforator-flap. She already had reconstruction of the nipple-areola-complex with tattooing and a local skin flap.

Complications occur infrequently. Partial flap loss has been reported as low as only 2.5%, total flap loss with less than 1%[25]. Problems regarding the venous anastomosis appear much more likely than problems with the arterial anastomosis. The most common complications include necrosis of the fat tissue of the flaps and seroma formation. The risk of bulging in DIEP flaps is reported as two thirds lower in comparison to TRAM flap reconstructions. Abdominal herniation occurred in fewer than 1% of all DIEP flaps compared with 3.9% in TRAM flaps[20,24,25]. However, current literature fails to prove a significant difference in the risk of developing abdominal bulge/hernia between ms-TRAM flap and DIEP flap based reconstructions[26]. Additionally, there is no significant difference in the risk of donor site morbidity between bilateral and unilateral DIEP flap breast reconstruction[26].

The SIEA flap is the least invasive option of free abdominal tissue transfer for breast reconstruction. It provides the same tissue as the DIEP flap, without injuring the anterior rectus sheath and no vessel dissection needs to be performed through the muscle (Figure 7). Consequently, the SIEA flap causes the least donor site morbidity of all abdominal flaps, eliminating the risk of developing unwanted abdominal bulk or herniation[27]. However, the dissection of the vascular pedicle requires a high level of expertise, mainly because of its variability in existence, location, and caliber. The superficial inferior epigastric vessels have noted to be absent in 13%-42% of dissections. Furthermore, vessels are often not in appropriate caliber to sufficiently support the perfusion of the tissue volume needed for breast reconstruction. As a consequence, the amount of skin and fat tissue, which may be transferred utilizing a SIEA flap, is limited[22,24,28].

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Figure 7 Example of a split superficial inferior epigastric artery-flap with both pedicles clearly visible. Since there is no injury to the rectus fascia, this the most desirable choice of flap from the lower abdomen.

The first free gluteal myocutaneous flap for breast reconstruction was performed by Fujino et al[33] in 1975. As the development of the perforator flap technique revolutionized the applicability of soft tissue transfer, gluteal flaps became popular in the 1990s[11]. Gluteal perforator flaps offer a great alternative for breast reconstruction in women who have more tissue available in the buttock area than in the lower abdomen. Similar to the DIEP and SIEA flaps, no sacrifice of muscle is required using this technique.

The superior and inferior GAP (S/I-GAP) flaps have been specified and modified by Allen et al[34-36]. The surgical procedure is similar to the DIEP flap. The gluteal vessel pedicle is dissected throughout the gluteus maximus muscle to their origin in the internal iliac artery. The pedicle is generally about 5-8 cm long, which provides sufficient length for a comfortable anastomosis and inset at the chest wall. A clear disadvantage of this method is in the necessary rearrangement of the patient from abdominal to supine position during surgery. GAP flaps are generally a safe reconstructive option. Vascular complications are reported in approximately 6%, total lap loss in 2% of all cases. However, approximately 4% of all patients require revisions because of donor site problems, such as contour deformity after SGAP, or scar issues after IGAP flaps[12,22,24].

Another, in our opinion more valuable flap of the gluteal region is the FCI flap. The FCI flap is based on the descending branch of the inferior gluteal artery with a very reliable location, good caliber and a pedicle length ranging up to 18 cm (Figure 8). Unlike other gluteal flaps, the vessels curl around the lower border of the gluteus maximus muscle. Therefore, no perforator dissection through the muscle is necessary. Studies demonstrated that even thin patients offer enough tissue to allow breast reconstruction with adequate volume[37], making the FCI flap a convincing alternative to standard free tissue breast reconstruction in certain cases. The tissue from this region is more compact and not as soft compared to the lower abdomen making it more suitable for reconstruction of firm breasts in younger patients (Figure 9).

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Figure 8 Example of a fasciocutaneous infragluteal-flap almost completely raised. At the undersurface of the flap, the flap’s main vessels, i.e., the descending branch of the inferior gluteal vessels, can be seen clearly. Additionally, a branch of the posterior femoral cutaneous nerve is visible and spared.

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Figure 9 A 49-year-old patient after bilateral nipple-sparing prophylactic mastectomy and immediate breast reconstruction with bilateral fasciocutaneous infragluteal-flap.

Since its first description for free tissue transfer in 1976[38] the gracilis flap has become a workhorse in autologous breast reconstruction. The TMG flap is an alternative method for patients who do not have adequate abdominal tissue, or seek to avoid abdominal scarring. The TMG flap is ideally suited for reconstruction of small to moderate sized breasts, providing excellent contour and projection[39]. The donor site is well hidden and harvesting the flap has no functional consequences[40].

The flap is designed with a semilunar skin island in the inner thigh with a mean volume of around 300 cc. The raising of the skin island is started close to the groin and harvested with the underlying fascia. The average pedicle length is reported as 6-8 cm, with an arterial diameter of 1.2 mm and a venous diameter of 2.8 mm. The artery is usually slightly smaller than the IMA, which usually does not preclude a safe anastomosis[41] (Figure 10).

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Figure 10 Intraoperative image of a completely harvested transverse myocutaneous gracilis flap with flap pedicle (short) and the relatively long saphenous vein as a venous supercharge.

Performing a unilateral TMG flap may cause asymmetry. The use in bilateral reconstruction is reported as one of the strongest advantages of the flap and even recommended as first choice, except for patients that would clearly benefit from an abdominoplasty (Figure 11). As with all flaps including a muscular component, the TMG flap is prone to volume loss resulting from neurogenic atrophy, but a true impact on cosmetic appearance has yet to be demonstrated[22,42]. A true disadvantage of the gracilis flap is the small size of the skin island. A single TMG flap may provide not enough tissue for sufficient reconstruction of a large breast. In this case, two TMG flaps or the usage of a combined infragluteal-transverse myocutaneus gracilis flap can be a viable option[43].

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Figure 11 Pre- and post-operative pictures after immediate bilateral skin-reducing breast reconstruction with a transverse musculocutaneous gracilis-flap and reconstruction of the nipple-areola-complex.