A Bipedicled Flap for Closure of the Anterolateral Thigh Flap Donor Site

Abstract

Summary: 

Anterolateral thigh (ALT) free flaps have become reliable options for head-to-toe reconstruction. Although perforator anatomy is fairly predictable, in cases of eccentric perforator location, we proposed shifting the entire flap laterally and preserving a medial bipedicled flap between the original incision and the new medial flap margin. This facilitates primary donor site closure instead of harvesting a flap larger than anticipated. We conducted a retrospective chart review of ALT flaps performed between 2007 and 2019 and identified patients who underwent bipedicled closure of the donor site. Demographics, flap characteristics, and surgical technique were evaluated. Six patients had bipedicled donor site closure related to primary perforators located lateral to the original flap design. The mean defect size was 91 cm², and bipedicled flap width ranged from 4 to 6 cm. All donor sites were closed primarily. Five of the donor thigh sites healed without complications, and 1 patient had superficial delayed healing of the medial bipedicled incision, which healed with local wound care. The ALT has become an invaluable flap in microsurgical reconstruction, yet it is not without limitations. Primary donor site closure is generally not feasible for larger flaps, thus necessitating skin grafting of the donor site and/or prolonged wound care. Our technique facilitates primary closure of the donor site in patients who otherwise would have required harvest of a larger than necessary flap based on eccentric perforator anatomy. The medial bipedicled flap is straightforward, reproducible, and allows for modifications of the original flap design to better fit the defect.

INTRODUCTION

The anterolateral thigh (ALT) perforator flap has become a workhorse in microsurgical reconstruction. This flap has the potential to provide ample soft tissue with reliable perforator anatomy, a consistently long pedicle length, and minimal donor site morbidity.^1–6 The anatomic landmarks for the flap have been well described, with the longitudinal axis of the flap centered over a line drawn from the anterior superior iliac spine to the superolateral patella that approximates the location of the intermuscular septum between vastus lateralis and rectus femoris.^7,8 The perforators are typically found within a 4-cm diameter circle around the midpoint of this line and are typically used for flap perfusion.⁹

Despite the reliability of these markings, there are occasional instances where the perforator of interest is located more laterally than expected when the flap is elevated. This may be due to a significant intramuscular course resulting in a more lateral perforator location, or if the markings were made without internal rotation of the foot, a medial displacement of the flap design. In this scenario, the surgeon must decide among 3 options: (1) harvesting a flap that is wider than anticipated to center the flap over the perforator, which may preclude primary donor site closure; (2) elevate the flap with an eccentrically located perforator along the lateral margin of the flap, which may compromise flap perfusion; or (3) change the perforator to an adjacent, less-desirable perforator.¹⁰

Considering that none of these options are ideal, the senior author has developed a technique that shifts the ALT flap design laterally so that it is centered over the perforator of interest. This preserves a medial bipedicled flap, which permits primary donor site closure. We provide a description of the technique, as well as our experience with 6 patients.

METHODS

We reviewed all patients who underwent ALT flap reconstruction by 2 of the authors between 2007 and 2019. Patients were included if they underwent ALT free flap reconstruction with bipedicled flap donor site closure (6 of 121 patients, 5%). Charts were reviewed for demographics, preoperative and operative details, and postoperative outcomes.

Surgical Technique

The ALT flap was designed according to the markings previously described and centered over the anticipated location of the B perforator based on preoperative and intraoperative handheld Doppler findings. The pinch test provides guidance for flap width. Subfascial dissection was used for flap elevation starting from the anterior margin of the flap, preserving all perforators, until the perforator of interest was identified. In all cases, the desired perforator was noted to be significantly more lateral on the undersurface of the flap than anticipated and resulted in an eccentric location within the initial flap design. To center the perforator within the flap, the flap design was transposed laterally and remarked (Fig. 1). The anterior margin of the new flap design comprised the lateral border of the bipedicled flap and was marked to preserve 4–6 cm of bipedicled flap width along its length to optimize vascularity. After the ALT flap was harvested, suprafascial dissection along the entire length of the bipedicled flap was performed. The bipedicled flap was then closed along its entire anterior length and then its posterior length.

Figure 1.: Photographs of a patient in whom a medial bipedicled flap was used to shift the design of the ALT flap to facilitate primary closure. A, Original flap design. B, Lateral shift of flap design, creating a 6-cm bipedicled flap. C, ALT flap elevated and shifted medial to the bipedicled flap. D, Primary closure of the donor site.

RESULTS

Over the 12-year period, the bipedicled flap donor site closure technique was used in 6 patients. In all cases, the perforator of choice was eccentrically located from the original flap design. The decision was made to shift the flap, thereby creating a bipedicled flap, to enable primary closure of the donor site.

The average age of the patients was 45.8 years (range, 22–63 years), and the average body mass index was 26.2 years (range, 18.6–35.3 years) (Table 1). Five patients were men, and 1 patient was a woman. In 5 patients, the ALT flap was a fasciocutaneous flap, and in 1 patient, a segment of the vastus lateralis was taken as part of the flap.

Table 1. - Patient Demographics

Patient	Age	Sex	BMI	Comorbidities	Indication for Procedure
1	49	M	27.9	CAD, HTN, MI, PVD	PVD, chronic wound
2	63	M	20.1	Alcohol abuse, HCV, PVD, seizure disorder	Necrotizing fasciitis
3	54	F	25.0	None	Chronic osteomyelitis
4	53	M	18.6	IVDU	Orbital sarcoma, previous XRT
5	34	M	35.3	None	Gustilo 3B open fracture
6	22	M	30.4	None	Gustilo 3B open fracture

BMI, body mass index; CAD, coronary artery disease; F, female; HTN, hypertension; HCV, hepatitis C virus; IVDU, intravenous drug use; M, male; MI, myocardial infarction; PVD, peripheral vascular disease; XRT, radiation therapy.

Five of the flaps were used to reconstruct defects of the lower extremity, and 1 was used for a maxillofacial defect. Indications for flap reconstruction included peripheral vascular disease, necrotizing fasciitis, chronic osteomyelitis with associated chronic wound, acute trauma with Gustilo 3B fracture, and orbital sarcoma. Average defect size was 91 cm² (range, 50–225 cm²), with ALT flap widths ranging from 6 to 8 cm. In all of the lower extremity cases, the posterior tibial vessels were used as recipient vessels, and the artery was sewn in using an end-to-side technique. In the maxillofacial reconstruction, contralateral facial vessels were used, which required interposition greater saphenous vein grafting.

The bipedicled flap enabled primary donor site closure in all patients. Five of the thigh donor sites healed without complications. One patient had delayed healing of the medial bipedicled incision, which was treated with local wound care. Five of the ALT flaps healed well, and 1 developed a small superficial wound, which was treated with local wound care.

DISCUSSION

The versatility of the ALT flap has led it to be our flap of choice when performing microsurgical reconstruction throughout all areas of the body. However, like all flaps, it has its limitations; one such being the inability to accurately predict where the dominant perforator will lie 100% of the time. Additionally, if a larger flap is taken, primary donor site closure is generally not feasible for flaps larger than 8 × 25 cm.

Traditionally, if the dominant perforator was more eccentrically or laterally located, we would have harvested a larger flap and then trimmed it down with inset. This often led to skin grafting of the donor site and/or prolonged wound care or wound vac therapy. This is not ideal for a number of reasons, one of which is that the skin grafting of the donor site has been shown to cause a decreased range of motion at the hip and knee joints, attributed to adhesions between the skin graft and the underlying muscle fascia.¹¹ Alternatively, we could have harvested a free vastus lateralis flap instead of a fasciocutaneous flap. However, we prefer the pliability of a fasciocutaneous flap and thus favor the bipedicled flap solution.

The creation of a bipedicled flap facilitates primary closure of the donor site and allows for modifications of the original flap design to better fit the defect. Our technique is reproducible and straightforward and would be useful for every microsurgeon to have in their armamentarium. Additionally, this technique may be applicable to a number of other perforator-based fasciocutaneous flaps to facilitate closure when the perforator of interest does not correlate with the preoperative markings.