Facial reconstruction with thinned anterolateral thigh free flap

Abstract

Facial reconstruction is challenging for plastic surgeons, as it can be difficult to decide the best approach. One technique that has been widely used is the anterolateral thigh (ALT) flap due to its numerous benefits. However, its thickness can be a drawback, especially regarding facial reconstruction. The thinning technique is not a new novel, but how to apply it to the ALT flap to get the best result hasn’t been reported yet. Our study involved 117 patients, and we used 73 thinned ALT flaps to determine the best method to increase the flap’s safety. After thinning, we significantly reduced the flap’s thickness from an average of 22.5 mm to 5.9 mm, making it more suitable for contouring purposes. We apply a thinned ALT flap for coverage, contouring, and recreating the facial 3D structure. The 12/45 flap has the chance to make the multiple-paddle ALT flap, which helps to reconstruct difficult positions even more flexibly. The key to successfully thinning the ALT flap is understanding the perforator’s structure and pathway through the fascia. With the thinning technique, we have overcome the limitations of the flap’s thickness, making it suitable for use in whole-body reconstruction. The ALT flap can overcome the restriction of its thickness and can be applied even more extensively in whole-body reconstruction.

Introduction

The anterolateral thigh flap has been a valuable tool in reconstructive surgeries for over 40 years and is now increasingly used for reconstructing facial lesions [1, 2]. It has several advantages, such as a stable and long vascular pedicle. It can be designed with various components like fascia, adipose, and cutaneous tissue to meet different purposes, such as covering, padding, and recreating three-dimensional structures [3, 4]. The size of the flapcan be adjusted; it is hairless, has a similar skin texture to facial skin, and has minimal color change for Asians. However, one disadvantage noted by many authors is that the flap can be too thick, especially when used to cover thin areas. Most surgeons prefer to leave the flap intact and perform a secondary flap thinning procedure through excision or liposuction to avoid complications like ischemia and flap necrosis. These interventions are performed 6–12 months after the first surgery. During this time, the imperfections in cosmetic results also cause patients to experience limitations in social communication, especially in the facial area [5, 6]. Not many surgeons perform thinning of the ALT flap for facial contouring [7]. The issue of how to safely thin the ALT flap is also being debated, from the thickness of the thin flap to the size of the fascial island [8]. These opinions are not based on the anatomical structure of the perforating vessels, so the choice of thinning method is not consistent. We performed on 117 patients using ALT flaps for all facial contouring procedures, of which 58 patients were reconstructed with 73 thinned ALT flaps. The structural characteristics of the perforators in the ALT flap should guide the choice of thinning method. This article shares our expertise in selecting the appropriate ALT flap thinning technique, including indications and specific techniques.

Patients and method

Between 2008 and 2021, a retrospective case series of 58 consecutive patients who underwent maxillofacial reconstruction with the thinned ALT were enrolled in our department. Patients in this study were between 13 and 80 years old, with an average age of 42.1. Among the patients, 26 were male and 32 were female. The patients had a range of defects that resulted from ablative surgery for local cancer tumors (17 patients, including 13 BCC and 4 SCC), 10 patients had radiation ulcers, 15 had skin tumors (such as neurofibromas, melanoma, or hemangiomas), 12 had burn scars, and 4 had defects resulting from NOMA or craniofacial cleft sequelae. The defects were located in various areas, including the forehead (7 cases), cheeks and nose (27 cases), oral cavity (6 cases, including 4 in the buccal mucosa and 2 in the tongue), lips and chin (6 cases), eyelid and socket (2 cases), and a combination of areas (10 cases).

Surgical technique

ALT flaps were harvested similarly by one team, and another team prepared the wound and the recipient vessels. Perforator vessels were checked using handheld Doppler imaging. The descending branch and perforators of the lateral circumflex femoral artery (LCFA) were identified through a subfascial approach. The perforators were then dissected retrogradely, according to their origin. Skin islands were elevated based on the size of the skin defect. We decided on the thinning method based on the origin and direction of the perforator. Assume that the perforator comes from the descending branch and runs perpendicular to the deep fascia. In this case, we will do microdissection thinning and leave a fascia island with a 1 cm radius around the perforator (Fig. 1A). This procedure is performed under the microscope by removing the fat lobules lying deep in the superficial fat layer, preserving as many blood vessels as possible at that level, and starting from the periphery toward the center of the flap. With microdissection thinning, the flap thickness was reduced to approximately 3–5 mm, comparable to reconstructing the 3D structure. If the perforator runs oblique to the deep fascia surface (60–80 degrees), we need to extend the fascia island radius around the perforator to 2–5 cm (Fig. 1B). In these cases, both primary and micro-thinning are available for the flap outside the fascia island radius. In the primary thinning method, the fat between the superficial and fascia lata was removed by blunt scissors, and subdermal vessels were conserved. This technique allows for a thickness of 5–9 mm. No thinning is performed if the perforator runs nearly transverse or parallel to the fascia (Fig. 1C, D). Finally, if the perforator does not originate from the LCFA, the retained fascia island needs to extend to a radius greater than 6 cm, and only primary thinning is available. The bipolar cautery is used for hemostasis in the superficial fascia, and we don’t use it when doing the microdissected thinning. In many cases, the facial defects are particular, and we may need to do customized thinning, which means there is a place where we do the primary thinning and, at other times, micro thinning. This type is suitable for covering cheek and lip unit defects. The thinning procedure was performed before the flap was elevated. Finally, the thinned flap was transferred to the recipient site for reconstruction. The flap pedicle was anastomosed in an end-to-end or side-to-end manner to the fascial or supertemporal arteries. Thinned flaps cover skin defects or recreate three-dimensional structures in the nose, lips, eyelids, cheeks, etc. If a particular case requires a multiple-paddle flap and the descending branch does not provide enough perforating vessels, we can use the perforator of the ipsilateral oblique branch or the perforator of the descending branch of the opposite thigh. The flap is used in a chimeric fabricated form. The donor site was closed primarily or with a skin graft. The flaps were monitored frequently within the initial 2-day postoperative period. Repairs were performed soon if an obstruction was suspected. Patients were discharged after approximately 12 days, and the flap survival, contour, and donor site were recorded.

Fig. 1

Anatomical structure of perforators. (A): 2 perforators run perpendicular to the surface of the deep fascia, which can be primarily or microdissected thinned; (B): Perforators run at a 45-degree angle to the fascia, primary thinning with skin islands larger than 4 cm; (C): The perforator at the distal end of the descending branch runs at an angle less than 45 degrees and no thinning were acquired; (D): oblique branch of LCFA and runs at an angle of 20 degrees, no thinning were acquired. (DB: Descending branch of the LCFA, OB: oblique branch of the LCFA, P: perforator, white arrow - direction of vessel flow, black arrow – indication of the vessel)

Results

The 73 thinned ALT flaps from 58 patients included in this study were used to restore defects in different parts of the face: 8 flaps for the forehead (11%), 22 flaps for the cheek (30%), 12 flaps for the nose (16.4%), 8 flaps for the eyelid, the lip and chin (11%), 10 flaps for the oral cavity (13%), and 13 flaps for combined areas (18%). There were 45 flaps used to cover defects, the remaining 18 for 3D reconstruction and 10 for combination reconstruction. Out of the total flaps, 44 were single flaps, 12 were multiple-paddle flaps, and two were fabricated chimeric. The skin paddle flap width varied from 3 to 14 cm, averaging 7.0 cm. The flap length ranged from 3 to 25 cm, averaging 13.2 cm. There were 80 perforating vessels present in 73 flaps. Of these, 90% (72) originated from the descending branch, 5% (4) from the contralateral descending branch, and 5% (4) from the ipsilateral oblique branch. The majority (80%) of the perforators go perpendicular, while the remaining 20% do not. The length of the flap pedicle was 10.3 cm (range: 5–16). The anterolateral thigh flap was used in the procedure as a primary thinning flap in 47 flaps and as a microdissected thin flap in 26 flaps. The thickness of the flap before thinning was measured to be 22.5 mm on average (with a range of 11–30 mm) and reduced to an average of 5.9 mm (with a range of 3–12 mm) after thinning. This represents a decrease of approximately 26.2%. The size of the fascia island around the main perforator was 1 cm in 6 flaps, 2–3 cm in 59 flaps, and greater than 4 cm in 8 flaps. The flap pedicle was anastomosed with facial vessels in 42 cases (72%) and supratemporal vessels in 16 cases (28%). The characteristics of the flaps are presented in Tables 1 and 2. The donor site was closed directly in 38 cases and with a skin graft in 20 cases. Three flaps (or 3.8%) had total necrosis due to damage to the pedicle. Two flaps experienced small ischemia at the distal end that required no intervention. The incidence of a well-survived flap was 96%. After 1–6 years of follow-up, patients reported satisfaction with the functional and esthetic results. Six patients required defatting after one year. Some of the patient’s photos are shown in Figs. 2, 3 and 4.

Table 1 Characteristics of ALT flap in the facial reconstruction

Table 2 The results of thinning flaps

Fig. 2

(A): A 24-year-old female patient with a hemifacial radiation-induced scar on the right cheek, forehead, upper lip, temporal, and facial asymmetry. (B): A right chimeric ALT flap was harvested. The flap with 10 × 15 cm was customized thinned for the cheek and lip, and the Flap with 10 × 10 cm was mainly thinned for the forehead. (C) The results after 40 months of follow-up

Fig. 3

(A): 33-year-old female patient with acid burn scar 3 years ago on her left cheek. (B): The ALT flap is 6 × 12 cm in size and gets the primary thinning from 30 mm to 7 cm; (C): results after 47 weeks

Fig. 4

(A): 24-year-old female patient with excessive scarring and thermal burns on the cheeks and nasal dorsum. (B): Chimeric flap harvested and thinned microdissected, flap (A) size 5 × 7 cm for nasal reconstruction, flap (B) size 6 × 8 cm for cheek reconstruction; (C): 25-month surgical results

Discussion

The ALT flap is a versatile material that reconstructsvarious body parts, including the face [1, 2]. Its main purpose in facial reconstruction is to cover and recreate the three-dimensional structure. The ALT flap has many advantages, such as long vascular pedicles, numerous perforators, low donor site morbidity, and multiple components that can be taken together [3]. However, one disadvantage of this flap is its great thickness compared to other flaps due to excess subcutaneous fat, especially in obese women. Thick flaps can result in unaesthetic outcomes and poor function and could negatively affect the patient’s psychology. As a solution, many authors choose secondary defatting to ensure flap survival during the first surgery [5, 6]. However, this is not the patient’s desire because the cost of multiple thinning sessions burdens many patients.

Thinning the perforator flap is not new. This technique was introduced by Kimura in 1998 but under different names, such as primary thinning and microdissection [9]. Later, thinning was applied by many authors to the ALT flap with a thinning level of up to 3–5 mm, thus avoiding the need for subsequent secondary debulking procedures and restoring a higher and quicker reinnervation. This technique has been successfully applied to head, face, neck, and extremity reconstructions [10,11,12]. In principle, primary thinning removes the layer of fat below the superficial fascia and retains the layer of fat above the superficial fascia. Microdissection thinning removes additional fat from the superficial fascia and is performed under a microscope. The thickness after obtained micro-thinning can be much smaller than that of primary thinning. However, the thinning technique is still highly debated [13, 14]. Many authors suggest using small flaps, thinning radially, or expanding the fascial island around the perforators with inconsistent sizes to ensure safety and avoid flap necrosis. There is no research on when to expand the fascial island and to what extent without affecting flap viability [15,16,17].

In our experience, we have encountered cases of flap necrosis when we used the thinning technique for the first time. In one case, the perforator originated from an oblique branch, and we left behind 2 cm of the fascia island. In another case, we used the perforator vessel from the transverse branch, which entered the fascia at a 45-degree angle and kept the fascia by 2 cm. In the third case, we thinned the flap measuring 8 × 9 cm to line the eye socket. However, the flap was placed in an orbital socket with a space that was too narrow and did not have a good blood supply base for the flap. The failure rate in our study was 3/73 (4.1%), as reported by Agostini et al. [18]. All of the cases with necrosis have the perforator in the center of the flap, and the incidence was similar to the report of Suh et al. [19].

We learned from our failures that thinning should only be done with flaps with perforators running perpendicular or nearly perpendicular to the deep fascial surface. These vessels can be performed with both microsurgical thinning and primary thinning. The more obliquely the perforator runs, the more it is necessary to expand the fascia island. The direction of further expansion of the fascia is in the direction of the perforators. Perforating vessels that run nearly parallel to the fascia are not selected for thinning. In these cases, it is best to keep the entire fascia layer intact, and the flap should not be thinned. Our study is consistent with Kimura’s classification of perforating vessels [20]. The vascular branches running perpendicularly are in group one of the Kimura. In this group, the perforator runs straight through the fascia, giving branch vessels close to the skin. Whether or not the fascia is left in place will not affect the flap’s blood supply. The oblique vessels belong to group two; in this group, the expansion of the fascial island is necessary to preserve the branching vessels running close to the fascial layer. The vessels running in parallel are type 3 and are not considered candidates for thinning techniques, and this perforator type has a higher chance of flap complications. The two flaps with distal necrosis were two large flaps of 14 × 18 cm and 12 × 22 cm but had only one perforator to the flap. We still use flaps up to 16 × 25 cm in size, but these flaps have to have more than one perforator vessel. We kept the fascia connected between the perforators even when performing microdissection thinning. The wider the flap, the better the received bed tissue must be with a good blood supply. This is the condition for the thinned flap to reestablish neovascularization after covering the defect.

The primary thinning technique in our study achieved an average of 6.1 mm, a reduction of up to 30%. Meanwhile, thinning by microdissection achieves 5.0 mm and a thinning of up to 19.6%. The fascial island is mostly retained at 2–3 cm, including in primary thinning. We indicate two crucial factors related to the thinning technique: First, the perforator must run perpendicularly, and only 2–3 cm of the fascial island should be retained. In this study, only a few cases required secondary thinning; these are reconstructive cases of complex 3D structures, such as total rhinoplasty or lip contouring. It can also create a multiple-paddle flap, unique to this flap, and easily reconstructs three-dimensional structures such as cheek, nose, and lip defects. The multiple-paddle ALT flap is also known for covering significant defects while causing minimal damage to the donor site. There are 14 (24.1%) cases where multiple-paddle flaps are used, in which the flaps are small. These flaps recreate complex defects such as complete cheeks, total nasal, or lip defects [21,22,23]. The limitation of this technique is that there is not always a penetrating vessel. Kimata’s study showed that 5.4% had no perforating vessels from external femoral circumflex artery branches [24]. Not all perforators run perpendicular to the fascia, and there are not always enough perforators to create a chimeric flap. Choosing the ALT flap on the opposite thigh or using a perforator vessel from the transverse branch allows for creation in a fabricated fashion as an alternative choice for reconstructing complex facial defects. Changing the habit of thinning surgery is not easy for surgeons in many centers worldwide.

Conclusion

While not a novel approach, plastic surgeons continue to face obstacles when deciding how and to what degree to thin free ALT flaps. The thinning technique used is based on the structure of the perforators. A thinned ALT flap remains a suitable option for reconstructing various body parts, such as the face, due to its safety and quickness, increasing the patient’s quality of life.