The versatile anterolateral thigh flap: a musculocutaneous flap in disguise in head and neck reconstruction

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<ul><li><p>British Journal of Plastic Surgery (2000), 53, 30-36 9 2000 The British Association of Plastic Surgeons Article no. BJPS. 1999.3250 _ / ..... </p><p>BRIT ISH JOURNAL OF PLAST IC SURGERY </p><p>The versatile anterolateral thigh flap: a musculocutaneous flap in disguise in head and neck reconstruction </p><p>E Demirkan, H.-C. Chen, E-C. Wei, H.-H. Chen, S.-G. Jung*, S.-E Hau* and C.-T. Liao* </p><p>Department of Plastic and Reconstructive Surgery and *Department of Otorhinolaryngology, Chang Gung Memorial Hospital and College of Medicine, Chang Gung University, Taipei, Taiwan </p><p>SUMMARY. In search of an alternative soft tissue free flap donor site to radial forearm flap and rectus abdominis flap in head and neck reconstruction, we used the anterolateral thigh flap for reconstruction of various defects in the head and neck in 59 patients. The aim was to demonstrate the versatility of this donor site and propose a new approach to achieve a safer flap dissection. With the exception of three cases, all defects resulted from excision of malignant tumours. The defects were categorised as full thickness defects of the mandible (33.9%), full thickness defects of the cheek (52.5%) and others (13.6%). During the flap dissection a direct septocutaneous pedicle was observed in 12% of the cases. In the remaining cases there were only musculocutaneous perforators and the flaps were raised either as a split vastus lateralis musculocutaneous flap (72%) or as a perforator flap (16%), depending on the required thickness. Total flap survival was 96.7% with one total and one partial failure and two re-explo- rations (3.3%). The mean follow-up time was 7.1 months (range: 1-12 months). In conclusion, the anterolateral thigh flap is a versatile and dependable flap that can be adapted to any type of defect by modifying the flap design and composition. It should be considered to be a musculocutaneous flap of the vastus lateralis muscle that can also be raised as a perforator flap. When harvested and used in this context, the flap dissection becomes very safe and consistent, nullifying the only major disadvantage associated with this donor site. 9 2000 The British Association of Plastic Surgeons </p><p>Keywords: anterolateral thigh flap, head and neck reconstruction, musculocutaneous flap. </p><p>The qualities of the ideal soft tissue free flap for head and neck reconstruction may be defined as: l versatil- ity in design, adequate tissue stock, superior texture, minimal donor site morbidity, availability of diverse tissue types on one pedicle, potential for reinnerva- tion, large and long pedicle, feasibility of two team approach, and most importantly, consistent anatomy for an easy and safe flap dissection. The anterolateral thigh flap, which was first described by Song et al in 1984, had all of these qualifications except for the last one. z4 It was originally described as a septocutaneous flap based on the descending branch of the lateral femoral circumflex artery. 2 However, it was later found that in the majority of cases there were only musculocutaneous perforators, 5 7 and moreover, both septocutaneous 8 and musculocutaneous perforators 9 could originate from vessels other than the descending branch of the lateral femoral circumflex artery. This variability in the vascular anatomy is the main factor which precludes widespread clinical use of this donor site despite reports of some successful series in the literature.3,10-13 </p><p>Two years ago, we began to use the anterolateral thigh flap in head and neck reconstruction in search of a new donor site that was versatile and had minimal donor site morbidity. After our initial experience with the flap dissection, we felt that this flap should be con- sidered to be a musculocutaneous flap of the vastus </p><p>lateralis muscle rather than a septocutaneous flap with frequently missing septocutaneous perforators. Then, we began to use this donor site mainly as a musculo- cutaneous flap alternative to rectus abdominis flap in reconstruction of medium to large size oromandibular defects. When required, a skin flap could always be harvested and even thin flaps could be obtained, obviating the use of radial forearm flaps. Here, we present 59 consecutive head and neck reconstructions illustrating the versatile use of the anterolateral thigh flap and propose a new dissection approach that makes the flap harvest easier and safer. </p><p>Patients and methods </p><p>Between January 1997 and March 1998, 59 patients underwent oral reconstruction using 60 anterolateral thigh flaps. Patients' ages ranged from 13 to 79 years with an average of 56 years. There were 55 males and 4 females. In 56 cases the defects resulted from excision of malignant tumours. In the other three, stricture of the cervical oesophagus due to corrosive injury, soft tissue defect in the cheek due to foreign body excision and secondary soft tissue deficit following previous microsurgical oromandibular reconstruction were the pathologic lesions. In oncologic cases most of the tumours were located in the buccal mucosa (67%) </p><p>30 </p></li><li><p>Anterolateral thigh musculocutaneous flap 31 </p><p>followed by the gum (10.6%), lower lip (7.1%), floor of the mouth (3.6%), hard palate (3.6%), tongue (1.8%), submandibular gland (1.8%), nose (1.8%), periorbital bone (1.8%) and maxillary sinus (1.8%). All were T3-4 tumours. Except for the cases of chondrosarcoma of the palate, periorbital sarcoma and basal cell carcinoma of the nose, all tumours were squamous cell carcinomas. Seventeen cases were recurrent tumours which were treated with surgical excision. Most of the patients (50/59) received radiotherapy following the reconstruc- tion. The types of defects are shown in Table 1 and the types of anterolateral thigh flaps used to reconstruct them in Table 2. The flaps were dissected in a predeter- mined fashion either as skin or musculocutaneous flaps dictated by the type of the defect. The dissection algo- rithm used is presented in Figure 1. </p><p>Table 1 Type and location of the defects </p><p>Description Number of patients </p><p>Mandible Composite 20 </p><p>Cheek Full-thickness 25 Full-thickness + maxilla + palate 6 </p><p>Intra-oral Mucosa 1 Mucosa + maxilla 1 Tongue l Sulcus + floor 1 Cervical oesophagus 1 </p><p>Face Nose + lower eyelid 2 Fronto-orbital area 1 </p><p>Total 59 </p><p>Doppler verification / \ </p><p>DEFECT </p><p>/ \ Skin F lap Musculocutaneous Flap </p><p>Flap design on the circle of perforators </p><p>Skin incision at the medial border </p><p>Explore the space between the rectus femoris and vastus lateralis </p><p>Septocutaneous perforator - </p><p>Explore musculocutaneous perforators </p><p>Septocutaneous perforator + </p><p>Complete the incision and raise the skin flap </p><p>J l Present </p><p>Raise a perforator flap </p><p>Figure 1--Dissection algorithm. </p><p>Absent </p><p>Shift to tensor fasciae latae or medial thigh flaps </p><p>Septocutaneous Septocutaneous perforator - perforator + </p><p>Isolate the proximal part Isolate a muscle branch of the descending branch and include in the </p><p>pedicle with the septocutaneous branch </p><p>Dissect proximally to / distally around the T pedicle; upon reaching Raise the muscle and the lateral division of the skin as a bipaddled or descending branch, ligate siamese flap the medial division and begin to split the vastus lateralis just below the lateral division </p></li><li><p>32 British Journal of Plastic Surgery </p><p>Table 2 Flap types used </p><p>Type Number </p><p>Skin Septocutaneous 7 Perforator 10 </p><p>Musculocutaneous 43 Total 60 </p><p>Flap dissection </p><p>With the patient in the supine position, a line is drawn from the anterior superior iliac spine to the supero- lateral border of the patella. This line represents the intermuscular septum between the rectus femoris and vastus lateralis muscles. Next, a circle with a 3 cm radius is marked at the midpoint of this line. When a musculocutaneous flap is going to be raised, it is cen- tred on this circle (Fig. 2A). Wolff and Grundmann's anatomic dissections in 60 cadavers showed that the main septocutaneous perforator was located within 3 cm of the midpoint of this line proximally and dis- tally in 95% of the cases. TM Recently, Kimata et al </p><p>reported a similar preponderance of perforators at the same location. 6 If a skin-only flap is required, then a Doppler verification of the perforators is performed and the skin flap is designed to include all of these per- forators. The inferolateral quadrant of this circle is the location of at least one perforator in 80% of the cases according to the Doppler studies of Xu et al : </p><p>Dissection begins at the medial border of the flap, which should be located over the rectus femoris muscle for two reasons: first to prevent injury to cutaneous perforators that may originate from the intermuscular septum, and second to have access to the anteromedial thigh flap region. The incision is made through the deep fascia and the flap is raised laterally for a short distance until the intermuscular septum between the rectus femoris and vastus lateralis is reached. At that point the descending branch of the lateral femoral cir- cumflex artery is explored and the presence of a direct septocutaneous perforator is verified (Fig. 2B). However, the chance of finding an isolated septocuta- neous perforator is quite low (12% of the cases in this study). Most of the time there is indeed a prominent branch taking off from the descending branch at the described location but it is either partially or com- pletely buried in the vastus lateralis muscle on its course to the skin (Fig. 2C). This musculocutaneous branch is called the lateral division of the descending branch. It is well described in the study of Xu et aP and </p><p>Rectus F~crts </p><p>Figure 2 (A) Flap design. The flap is centred on the lower lateral quadrant of a line drawn from the anterior superior iliac spine to the lateral border of the patella. The anterior border of the flap should be located on the rectus femoris muscle which is medial to this line. (B) A scptocutaneous perfbrator may be found in the intermuscular septum between the vastus lateralis and rectus femoris muscles in only 12% of the cases. (C) A prominent branch taking off from the descending branch may be found in the intermuscular septum proximally but it is usually buried into the vastus lateralis muscle (arrow) in its distal course to the skin. It is called the lateral division. (D) A musculocutaneous flap can be raised by splitting the muscle tangentially just below the lateral division in a proximal to distal direction. The motor nerve of the muscle (arrow) should be preserved. </p></li><li><p>Anterolateral thigh musculocutaneous flap 33 </p><p>referred to as the proximal muscular branch by Wolff and Howaldt. is It usually enters the muscle at the junc- tion of its cranial and middle thirds and about halfway in its thickness. It is always accompanied by a branch of the motor nerve. If some muscle is desired to be included in the flap, then with a proximal to distal dis- section from the pedicle, the muscle is split tangentially on its long axis just below the lateral division and the upper portion is raised with the skin flap (Fig. 2D). Musculocutaneous perforators are not explored but the part of the muscle under the circle of perforators is always included. Peripheral to this only the deep fascia needs to be included. By raising the flap in a centripetal fashion from the lateral division of the descending branch, it is always possible to identify all perforators and further trim the muscle for a custom fit to the indi- vidual defect. The largest flap raised in this way with- out partial loss was 34 x 14 cm in dimension. </p><p>When a skin-only flap is planned and no septocuta- neous perforators can be found, then the largest musculocutaneous perforator is explored. The perfora- tor is usually found in the cranial one third or at the junction of the cranial and middle thirds of the muscle. The possibility of finding a major perforator that may descend from the transverse branch and enter the muscle from its superior aspect quite superficially (described as the horizontal perforator by Zhou et al) 9 should be kept in mind while incising the upper border of the flap. If there is more than one perforator the largest one should be followed and after verification of its origin others can be divided and the incision can be completed. One musculocutaneous perforator is suffi- cient to raise a large skin flap (largest 20 x 12 cm in this study). Perforators can be skeletonised as described by Kimura and SatohJ 6 The musculocutaneous perfora- tor originated from the transverse branch of the lateral femoral circumflex artery in 10% of the cases in this study. </p><p>If a musculocutaneous flap is planned and dissec- tion reveals a septocutaneous perforator, then the skin and muscle parts may be raised on different branches of the same vascular pedicle as a bipaddled composite flap. </p><p>If no septo- or musculocutaneous perforators are found or if they are inadvertently divided, the dissected skin island can be salvaged as a tensor fascia lata flap based on the transverse branch by extending the inci- sion and flap design laterally to include the fasciae latae zone. Alternatively, an anteromedial thigh flap can be raised through the same incision. The skin flap medial to the initial vertical incision on the rectus femoris muscle can be undermined below the deep fas- cia to explore the anteromedial thigh flap perforators that are located between the rectus femoris and vastus intermedius muscles. They originate from the innomi- nate artery, which is a direct branch of the lateral femoral circumflex artery or an extension of its descending branch. Therefore it is better to avoid a cir- cumferential incision at the beginning of the flap dis- section until the vascular pedicle is clearly identified and preserved. The main trunk of the motor nerve to the vastus lateralis muscle and its branches to </p><p>the remaining parts of the muscle should also be preserved. If a sensory flap is desired lateral femoral musculocutaneous nerve innervating the anterolateral thigh region may be dissected on its course above the deep fascia and included in the flap. Motor reinnerva- tion of the myocutaneous flap is also possible by means of the motor branch accompanying the vascular pedicle. </p><p>Results </p><p>Total flap survival rate was 96.6% with one total and one partial failure. The total failure occurred in a case where the flap was dissected as a perforator flap. In this case, as an anatomical variant, the artery of the lateral division did not follow the vein and the flap was inad- vertently raised on the part of the pedicle that con- tained only the vein and the nerve. The defect was reconstructed with the contralateral anterolateral thigh flap. The partial flap loss was due to infection. Two re-explorations were done due to venous congestion (3.3%: 2 out of 60 flaps). One was found to be related to tight skin sutures and the other to a haematoma in the neck. Both flaps were salvaged. Two patients experienced wound dehiscence and were treated conservatively. </p><p>The donor sites were closed by a skin graft in 18 cases. Prima...</p></li></ul>

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