Pedicled Bilateral Deep Inferior Epigastric Perforator Flap With Intraflap Anastomosis for Hip/Thigh Reconstruction

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A 50-year-old woman was diagnosed with high-grade spindle cell sarcoma of her right thigh and groin. She underwent neoadjuvant radiation and wide local excision of the mass by orthopedic oncology. The mass measured 14 × 9 × 14.3 cm and closely approximated the femoral artery and vein, requiring complex reconstruction (Figure 1). Due to the large size of the defect, we elected to utilize a bilateral deep inferior epigastric perforator (DIEP) flap with an intraflap anastomosis. (Figure 2). The proximal position of the defect made it amenable for a pedicled flap. The flap was able to cover the defect adequately with an acceptable contour. Good perfusion was confirmed using indocyanine green angiography. The patient was discharged home on postoperative day 7 after an uneventful hospital course. At 3 months, both her flap and donor site were well healed with only some small areas of incision that needed minor wound care.

Figure 1.(A) Magnetic resonance imaging of high-grade spindle cell sarcoma; (B) preoperative assessment prior to excision.

Figure 2.(A) Final defect; (B) immediately postoperative reconstruction.

The DIEP free flap is most widely used for autologous breast reconstruction in patients who have had a mastectomy. Typically, a unipedicled lower abdominal flap is sufficient for each breast mound. However, in some cases, for example, in women with large breasts or those with scant abdominal tissue, a bipedicled flap using the bilateral lower abdomen may be needed to reconstruct a unilateral breast defect adequately.¹ In these scenarios, both sides of the lower abdomen are utilized for the same flap, allowing the surgeon to harvest a significantly larger volume of tissue. In these instances, either an intraflap anastomosis between the 2 sides is performed or the 2 pedicles are anastomosed anterograde to the internal mammary vessels. While the bilateral DIEP flap is most frequently used in unilateral breast reconstruction, it is versatile and can also be utilized in other areas of the body in the appropriate candidate, such as the lower extremity or perineal area.² This can be accomplished as a free flap if there are adequate recipient vessels for anastomosis or as a pedicled flap if the defect is near the lower abdominal tissue and there is sufficient vessel length. Here we will discuss the utility of a pedicled bilateral DIEP for proximal thigh reconstruction.

Perfusion zones for lower abdomen flaps have been described to help surgeons estimate the approximate tissue territory with reliable perfusion. Hartrampf Zones of Perfusion were the first to illustrate these zones for the transverse rectus abdominis muscle flap and refer to the subdivision of the lower abdominal flap as 4 equal zones based on their level of perfusion and viability.³ Zone I is described as the most perfused and reliable area for flap reconstruction, with Zone IV being the most distant one, and therefore the least perfused and unlikely to be viable (Figure 3A). The Hartrampf Zones of Perfusion most accurately illustrate vascularity for a DIEP flap when the flap is based on a medial row perforator. Alternatively, a more recently described perfusion concept, the Saint-Cyr Perfusion Zones, labels the zone's viability as depending on the row position of the perforator harvested: lateral versus medial (Figure 3B).

Figure 3A. Hartrampf Zones of perfusion. (Illustration by Sterling Jones, 2023.)

Figure 3B. Lateral and medial perforator rows. (Illustration by Sterling Jones, 2023.)

In either description, there is often not adequate perfusion across the entire single DIEP flap based on 1 perforator. There are several techniques that optimize perfusion, one being the use of an intraflap anastomosis. For example, in the case presented above, the pedicle from the left hemi-abdomen was anastomosed to a large side branch of the right hemi-abdomen pedicle corresponding to the cut end of the lateral row. (Figures 4, 5). Following completion of anastomoses, intraoperative SPY can be used to assess appropriate tissue perfusion across all zones of tissue, including Zone IV. In this case, the single bilateral DIEP was used as a pedicled flap and tunneled underneath the rectus abdominis, exiting lateral to the rectus abdominis to ultimately cover the defect on the proximal thigh. If an intraflap anastomosis cannot be accomplished, the surgeon can instead consider supercharging the flap vessels in the wound bed. In this case, this likely would have been the radiated femoral artery and vein, which would have increased the technical difficulty of this case.

Figure 4. Intraflap anastomosis illustration (A) division of contralateral DIE vessels proximally (B) anastomosis of contralateral DIE vessels to the recipients (Illustration by Jenny Yu, 2023).

Figure 5. Intraflap anastomosis from the above case (A) single bipedicled DIEP flap after intraflap anastomosis (B) close-up view of the end-to-end sewn arterial anastomosis and venous coupler anastomoses, 2.0 mm and 1.5 mm.

There are several commonly used methods for the reconstruction of lower extremity defects, including but not limited to the anterolateral thigh flap, the gastrocnemius flap, the latissimus dorsi free flap, the soleus muscle flap, and abdominally based flaps.⁴ The choice of flap often depends on the specific location and size of the soft tissue defect, the availability of nearby tissue, and the patient's overall health and medical history.

Lower extremity reconstruction can be challenging due to limited local tissue options and complex anatomy. Harvesting a bilateral DIEP with intraflap anastomosis may be an appropriate option for reconstruction in various scenarios: namely, in cases of large soft tissue defects. While the latissimus dorsi flap is often a popular option for large defect coverage in the lower extremity, it must be used as a free flap. Patients who have suboptimal recipient vessels, such as those affected by radiation, infection, or trauma, may not be ideal candidates for a free flap. For these patients, a pedicled flap, such as a pedicled bilateral DIEP, could serve as a suitable solution. Additionally, the patient commonly must be repositioned to the prone position intraoperatively to harvest a latissimus flap, presenting more challenges.

An anterolateral thigh (ALT) flap would also have been a reasonable option in this patient. However, the size of the defect would likely have required a skin graft for the donor site. A pedicled ipsilateral ALT flap also would have made the patient more prone to lower extremity lymphedema due to reduced proximal leg skin and subcutaneous tissue. A free ALT would again run into the issue of a difficult anastomosis.

Abdominal-based flaps possess great characteristics for flap mobilization due to consistent anatomy, excess tissue for mobilization, and an abundant superficial and deep venous system.¹ Rectus abdominis musculocutaneous flaps can also be considered; however, these flaps present more donor site morbidity than the DIEP, with a higher risk of abdominal wall weakness, bulging, and hernia formation.

Harvesting a bilateral DIEP flap involves complex microsurgery, requiring a skilled microsurgeon to perform a technically demanding dissection and vessel anastomosis. This process can contribute to a longer surgery time and extended recovery period compared with other reconstructive techniques. Patients with previous abdominal surgery or liposuction, or those lacking sufficient abdominal tissue, might be considered poor candidates for a DIEP flap.⁵

Performing an intraflap anastomosis is not always technically feasible. It requires a side branch or distal continuation of the deep inferior epigastric artery large enough to accommodate the contralateral pedicle. This is often dependent on patient anatomy. DIEP flaps with type II pedicle branching patterns tend to have a large branch point as it splits into medial and lateral branches. The unused branch that is not used to supply the DIEP flap with perfusion can then be divided and is typically of large enough caliber for the intraflap anastomosis to be performed. If the vein or artery drops below 1 mm in diameter, then anastomosis becomes more technically challenging and supercharging the flap should be considered.

Another concern is potential donor site morbidity. Even though the DIEP flap spares the rectus abdominis muscle, dissecting through the rectus abdominis muscle and further disruption of abdominal tissue can still lead to complications, such as hernia formation and pain. As with any flap, there is a risk of flap-related complications, such as partial or complete flap loss, flap necrosis, or infection, which can have significant consequences for the patient and may require additional surgeries. Utilization of SPY intraoperatively to assess flap perfusion has been shown to decrease these flap complications.⁶

Despite these challenges, the bilateral DIEP flap remains a valuable option for select proximal thigh defects. It offers distinct advantages, particularly when other options may not provide sufficient volume. Ultimately, a careful evaluation of the patient's individual circumstances and the surgeon's expertise play a vital role in determining the most appropriate reconstructive approach, aiming to achieve optimal surgical outcomes and minimize potential complications.