Journal of Plastic, Reconstructive & Aesthetic Surgery (2010) 63, e465ee468

CASE REPORT

Distally based anterolateral-thigh (ALT) flap withthe aid of multidetector computed tomography

C. Heo*, S. Eun, R. Bae, K. Minn

Department of Plastic and Reconstructive Surgery, The College of Medicine, Seoul National University, 28 Yeongun-dong,Chongno-gu, Seoul 110-744, Republic of Korea

Received 2 June 2009; accepted 13 August 2009

KEYWORDSKnee reconstruction;Anterolateral-thigh flap(ALT flap);Multidetector CT(MDCT)

* Corresponding author. DepartmentTel.: þ82 31 787 7222; fax: þ82 31 78

E-mail address: lionheo@snu.ac.kr

1748-6815/$-seefrontmatterª2009Britdoi:10.1016/j.bjps.2009.08.009

Summary The applicability of the proximally based pedicled anterolateral thigh (ALT) flaphas been well described with good results, but the use of a distally based ALT flap aroundthe knee has not been fairly presented. The case of a male patient with a soft-tissue defectaround the knee who underwent skin reconstruction based on an ipsilateral distally basedALT flap is presented. Multidetector-computed tomography (MDCT) was used to study thevessels of the lower extremity, which allowed easy interpretation as it provided anatomicalimages with three-dimensional anatomy reconstructions. Because of the knowledge of theanatomical connections with the lateral femoral circumflex artery (LFCA) and the superiorlateral genicular artery (SLGA), the distally based ALT flap could be safely transferred.Soft-tissue reconstruction around the knee using the distally based ALT flap could also be per-formed safely and reliably with the aid of MDCT.ª 2009 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published byElsevier Ltd. All rights reserved.

Contracture is a frequent sequela of a soft-tissue injuryin a traumatised knee. Even though knee joint surgery isproper in this case, the skin injuries around the knee canlead to contractures, which may result in variable gradesof gait impairment. The release of these contracturesresults in large skin defects that necessitate soft-tissuereconstruction around the knee. These defects can betreated with local or free flaps. The anterolateral thigh

of Plastic Surgery, 166 Gumi-ro, B7 4058.(C. Heo).

ishAssociationofPlastic,Reconstruc

(ALT) flap has gained great popularity in Asians, and theuse of this flap, whether the local or free-flap pattern,provides many distinct advantages compared with theuse of the conventional free flaps.1e5 The authors’recent experience with the use of this versatile flap forthe reconstruction of a skin defect after release ofa post-traumatic cicatrisation around the knee ispresented.

undang-gu, Seongnam-si, Gyeonggi-do 464-707, Republic of Korea.

tiveandAestheticSurgeons.PublishedbyElsevierLtd.All rightsreserved.

e466 C. Heo et al.

Case report

A 56-year-old man was referred to the authors’ departmentfor the treatment of a post-traumatic scar contracture ofhis knee joint, which resulted from a vehicle accident2-years earlier. Various reconstruction options were dis-cussed with the patient, and he opted for autologous tissuereconstruction. Thus, a skin-resurfacing operation wasplanned to reconstruct the large defect, using a distallybased ALT flap (Figure 1).

Multidetector computed tomography (MDCT)angiography

Preoperative computed tomography (CT) angiography wasperformed with the use of a 64-slice multidetectorcomputed tomography (MDCT) scanner (Brilliance 64; Phi-lips Medical Systems, Best, the Netherlands). The scanningprotocol was as follows: 64� 0.625 mm section collimation,0.5 s rotation time, pitch of 0.732, 512� 512 matrix, 120 kVtube voltage and 250 mAs. A 140-ml bolus (Visipaque 270;Amersham Health Centre, Little Chalfont, England) wasintravenously injected (3.5 ml s�1) through an 18-gaugeintravenous (IV) catheter inserted into an antecubital vein.Using the bolus-tracking method with a power injector(Stellant, Medrad, Warrendale, PA, USA), a region ofinterest was placed in the lower abdominal aorta, and thescan was automatically initiated 5 s after the selectedthreshold (200 HU) was reached. The patient was placed ina prone position on a CT table in the exact manner that wasto be used in the surgery. Sections were obtained from theumbilicus to the part of the distal femur during a singlebreath hold. The volumetric data that were acquired werethen used to reconstruct images with a slice width of 1 mmand a reconstruction interval of 0.4 mm.

The axial images were processed and reformatted intomaximum-intensity projections (MIP) and 3D-volume-rendered (3D-VR) reconstructions, using commerciallyavailable software (Rapidia, Infinite, Seoul, Korea). Theentire course of the lateral femoral circumflex arteries,

Figure 1 The preoperative marking of the scar tissue on theknee and the design of the flap.

their branching pattern and anatomical variation and thepresence of any abnormality were evaluated in both thedonor and recipient sites (Figure 2). The arterial perfora-tors from the lateral femoral circumflex artery were iden-tified, and the exact location at which the perforator withthe widest diameter pierced the fascia was pinpointed onthe skin surface through 3D-VR reconstruction. Theselected images were transferred to the picture archivingand communications (PACS) system. At the time of thesurgery, the location of the arterial perforator was markedon the patient’s skin, making reference to the recon-structed images.

Operative techniques

The patient was placed in a prone position on the operatingtable, and the recipient and donor sites were prepared anddraped. All the flaps were raised through the standarddissection technique.2,6,7 A straight line was markedbetween the anterior superior iliac spine and the lateral edgeof the patella. The midpoint of this line was identified, anda circle of 2 cm radius was outlined. The perforators that areusually located within this area were detected through MDCTpreoperatively. The 10� 8 cm flap was marked and centredover the perforators (Figure 3). A medial incision was thenmade above the rectus femoris muscle, which was deepeneddown to the subfascial plane. The dissection was continuedunderneath the deep fascia and was extended laterally untilthe perforator was encountered. The septocutaneousperforator was identified, and the dissection was continuedlaterally towards the intramuscular space between therectus femoris and vastus lateralis muscles to identify themain descending branch of the lateral femoral circumflexartery (LFCA). After the dissection of the perforating vessels,

Figure 2 Posterior view of the MIP-reformatted imageshowing the descending branch of the left lateral femoralcircumflex artery. The entire course and branching pattern ofthe artery are clearly shown. The lateral genicular artery isclosely connected with the descending branch of the leftlateral femoral circumflex artery (arrow).

Figure 3 A 8.0� 10.0-cm distally based anterolateral-thighflap was harvested to cover the defect.

Figure 5 Long-term postoperative photos.

Distally based anterolateral-thigh (ALT) Flap e467

the descending branch of the LFCA was dissected proximallyat 10 cm, and distally at 6 cm proximally to the patella. Atthis point, a vascular clamp was used to temporarily occludethe proximal blood supply, and the perfusion of the distallybased flap was estimated as excellent. The proximal pediclewas then transected and added to the flap as a precaution incase of vascular insufficiency after flap transposition. Theflap was then transposed and made to cover the defect on theknee joint (Figure 4). The donor site was closed in layers overa suction drain after separately approximating the fascia andskin. The patient was discharged on postoperative day 5.After 2 months, no complications were reported, and thelong-term result was found to be functionally and cosmeti-cally satisfactory (Figure 5).

Discussion

The free ALT flap has become the most ample and versatileflap for the reconstruction of skin and soft-tissue defectsbecause of its reliability, remarkably long pedicle,

Figure 4 The flap was transferred to cover the defect.

versatility, minor donor-site morbidity and large potentialsize. Despite the anatomical variation of the perforators,the anatomy and the dissection technique of the ALT flaphave become well established.1e8 The island ALT flap hastwo pivot points: the proximal pivot point, located distallyto the origin of LCFA from the profunda femoris system; andthe distal pivot point, located proximally to the anasto-motic site of the descending branch of the LCFA with thelateral superior genicular artery, approximately 6 cm abovethe patella. Both the proximally and distally based ALTflaps have medial and lateral arcs of rotation and could berotated 180�. The radius of this arc is the length of thevascular pedicle (perforator and descending branch),depending on the location of the perforator vessel and theorientation of the skin paddle.5e8 The distally based flapwas advanced forward, without any rotation, to cover theanterior aspect of the knee joint (theoretically, it can berotated laterally or medially to cover the lateral or medialaspect of the knee, respectively). A pedicled ALT flap canbe transferred either proximally or distally, from on theumbilicus to the tibial tuberosity, within a distance ofapproximately 60 cm.6,7 Preoperative marking speeds upthe surgical dissection and makes it much easier to find thevessel intra-operatively. Preoperative Doppler sonographycan provide an overall view of the distribution of the indi-vidual perforating vessels but does not provide a definiteplace in the planning of the free microvascular perforatorflaps. Anatomical variation renders the microsurgicaldissection significantly more difficult and can even threatenthe success of the flap by damaging the delicate venaecomitantes.9 The advances of CT technology, especiallyMDCT, have achieved noninvasive vascular imaging withhigh spatial and temporal resolution. MDCT angiographyallows a precise evaluation of the origin, course and rela-tions of small-diameter vessels in both the donor andrecipient sites. Recently, several investigators reportedtheir initial experiences of the successful use of MDCT formapping the lateralefemoralecircumflexeartery perfo-rator for the ALT flap10,11 In this case report, preoperativeMDCT angiography provided an accurate vascular map ofthe lateralefemoralecircumflexeartery perforator. The

e468 C. Heo et al.

reformatted images were easy to interpret because theyclearly demonstrated a multidimensional overview of thearterial anatomy and the anastomotic site of the descend-ing branch of the LFCA with the lateral superior genicularartery. This technique precisely localised the arterialperforator and was useful in surgical planning. Based on theindividual anatomical demonstrations of the perforatingvessels, it was determined that even individual perforatorflaps can be designed using this method. It also allowsa virtual anatomy dissection of a patient to be carried outon the computer.

Conflict-of-interest

None.

Ethical approval

Approved by the Local Ethical Committee.

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