Anatomic Variations of the Deep Femoral Artery and Its Branches: Clinical Implications on Anterolateral Thigh Harvesting

The deep femoral artery (DFA) is the largest branch of the common femoral artery (CFA), supplying with its branches, the medial circumflex femoral artery (MCFA) and lateral circumflex femoral artery (LCFA), the thigh muscles, the hip joint, and the femur. Their anatomical variations have a great impact on both interventional and surgical procedures. The anterolateral thigh (ALT) flap, a versatile soft tissue with highly increasing use in reconstructive surgery, is noticeably influenced by this variability. A total of 25 articles were incorporated into the review. Studies conducted after the year 2009 were included. After the assessment of all studies included, we concluded that the DFΑ arises from the CFA with a varying site of origin, the posterolateral being the prevalent one found in 51.32% of cases. Of all cases studied, the MCFA and the LCFA most often originated from the DFA in 63.125% and 74.92%, respectively, but the CFA constitutes another frequent source of origin in 27% and 12.12% of cases, respectively. The descending branch of the lateral circumflex femoral artery (dLCFA) is the prominent pedicle in the ALT flap, originating from the LCFA in 83.55% of cases. However, the presence of an oblique lateral circumflex femoral artery (oLCFA) branch with changeable origination was observed. Knowledge of the anatomical variants in the deep femoral artery is imperative both for interventional radiologists and surgeons. Especially in reconstructive surgery, the possibility for different sources supplying the skin and the pedicle compel surgeons to acquire an awareness of this subject.


Introduction And Background
Anatomic variations of the profunda femoris or deep femoral artery (DFA) constitute a matter of great interest to anatomists, surgeons, and interventional radiologists due to their significant clinical relevance [1]. The DFA is the biggest branch of the lateral or posterior aspect of the common femoral artery (CFA) in the femoral triangle, located 2 -6 cm below the inguinal ligament [2]. It is the main vessel for the blood supply of the adductors, flexors, and extensors thigh muscles, as well as of the hip joint and the femur [3][4]. Moreover, it plays a crucial role in the collateral blood flow between the lower pelvis and the infrapopliteal circulation [5]. The major branches of the DFA are the lateral circumflex femoral artery (LCFA) from its lateral aspect and the medial circumflex femoral artery (MCFA) from its medial wall [6]. The varying vascular anatomy of these vessels is of the utmost importance due to their involvement in vascular, orthopedic, and plastic and reconstructive surgery [7][8][9][10].
Knowledge of the exact origin of the LCFA is important for surgeons when applying anesthesia to the femoral nerve (FN), in orthopedic surgeries during femoral and hip procedures, when harvesting an anterolateral thigh (ALT) flap in reconstructive surgery, in aortopopliteal bypass, in extra/intracranial bypass surgeries, but also coronary artery bypass grafting [7][8][9][11][12][13]. Knowledge of the MCFA origin and course variations is pivotal when performing both trochanteric and intertrochanteric osteotomies, in a total arthroplasty to avoid iatrogenic avascular necrosis of the head of the femur, and during flap plastic surgery, as well as in interventional radiology during puncture of the femoral artery [14][15][16][17].
The ALT flap has become a particularly popular choice for reconstruction with unsurpassed utility [18][19]. The vascular supply of the ALT flap most often consists of one to three cutaneous branches of the descending branch of the lateral circumflex femoral artery (dLCFA). However, anatomical variations of the latter make the ALT flap riskier than other flaps during its harvesting, thus necessitating adequate awareness of the region [20][21][22].
This study aims to report and illustrate the variable patterns of the origin, course, and ramification of the profunda femoris artery (PFA) and its branches, as well as summarizing the literature data on this anatomical issue.
A thorough search was conducted in the PubMed database for eligible articles from 2009 to 2020. All articles connected to DFA and ALT flap variations were entirely searched to find out all possibly pertinent information. The keywords used were the following: deep femoral artery variations, profunda femoris artery variations, MCFA variations, LCFA variations, and ALT flap variations. The search included all studies containing information about the DFA and its branches, the position of origin and morphometrics, as well as data about the vascular anatomy of the ALT flap in human subjects. The exclusion criteria were (1) articles pertaining irrelevant or inaccurate data, (2) studies containing patients with innate pathological conditions regarding the femoral region, (3) studies performed on animals, (4) articles written in languages unfamiliar to the author, and (5) articles published before the year 2009. There were no limitations imposed concerning race, age, sex, and journal. Case reports were also included. No efforts were made to search for unpublished material.

Review
One hundred and sixty-nine articles were initially taken into consideration. After applying the above-mentioned exclusion criteria, a sum of 25 articles was finally included in the review, analyzing a total number of 2,157 lower limbs. Those studies have covered a considerable geographical width originating from India, France, Serbia, Japan, Italy, Poland, Montenegro, Athens, Arabia, Turkey, Kenya, Africa, China, Taiwan, Singapore, Australia, Thailand, and Ohio from the United States (US). The prevalent type of study was cadaveric, while others based their results on computed tomography (CT), the computed tomography angiography (CTA) technique, and intraoperative findings during flap harvesting. The main characteristics of the studies included are depicted in Table 1.  Figure 1) [45]. The origin of the MCFA has been the study of research in nine out of 25 studies, including three case reports, and presented high variability (Table 3) [5, 23-25, 27-30, 34]. The origin of the LCFA was illustrated in eight studies, three of which were case reports (Table 4) [5,11,25,[27][28][29][30]34]. The specimens were categorized according to sex in only one study and to the side in another one.

Variability of the anterolateral thigh flap perforators
The studies described the various origins of the main perforator of the ALT flap. From the 11 studies included, seven were clinically based on ALT flap reconstruction (one case report), three included the CTA technique, and one was cadaveric. In five studies, the dLCFA was presented as the principal vessel vascularizing the ALT flap, whereas an oblique branch was delineated in four studies.  embalmed human extremities demonstrated that the DFA arose from the CFA in more than 90% of cases and from the CFA by a common trunk with the MCFA in 10% of the cases [5]. It was absent on the right side in 5% of the cases. The origin of the DFA from the mid-inguinal point (MIP) was 3.56 cm and 3.195 cm on the right and left side of the specimens, correspondingly. Concerning the position of origin, the DFA originated from the posterolateral wall of the CFA in 50% of the specimens on the right and in 70% on the left limb. The second most frequent position was the posterior (40% on right, 10% on left), followed by the lateral (5%), and the posteromedial position (5%). The MCFA arose from the CFA in 50% of the right limbs and 35% of the left limbs, in a mean distance from the MIP of 2.71 cm and 2.65 cm, respectively. The origin of the MCFA was from the DFA in 40% of the right and 60% of the left specimens, being at a distance of 3.96 and 4.85 cm from the MIP, respectively. It arose from the CFA as a common trunk with the DFA in 15% of cases. The most common site of origin was the medial site, whereas the posterior site was the least common. As for the LCFA, its source of origin appeared to be the DFA in 80% of the right specimens at a distance of 5.63 cm from the MIP and in 70% of the left specimens at a distance of 5.37 cm. It was from the CFA in a lower percentage, at a distance of 5.63 cm and 5.37 cm from the MIP on the right and left sites, respectively. The most frequent site of origin for the LCFA was the lateral site in 75% of the right and 100% of the left limbs.
Another cadaveric study conducted on 42 thighs in Serbia by Lalovic et al. illustrated that the MCFA originated from the DFA in 59.5% of cases, at a mean distance of 57.9 ± 19.5 mm from the MIP [23]. It arose from the FA in 33.3% of cases, being at a distance of 44.2 ± 13.5 mm from the MIP. The least usual type of origin was by a common trunk with the DFA (2.4%). It was absent in 4.8% of specimens. There was no statistically significant difference between the right and left limbs or males and females.
A study carried out by Zlotorowicz et al. in Poland analyzed 100 CTAs and concluded that both the MCFA and the LCFA derived from the DFA in 50% of the extremities [24]. In 31% of the cases, the MCFA arose from the CFA or the superficial femoral artery (SFA), whereas the LCFA arose from the DFA. In another 15% of the extremities, the LCFA originated from the CFA or the SFA, while the MCFA originated from the DFA. In two cases, they both arose from the CFA, whereas in one case, they both derived from the CFA by a common trunk. In one case, the MCFA was completely absent.
The microdissection performed on 30 fetuses in Montenegro by Vuksanovic-Bozaric et al. depicted that the most frequent origin of the MCFA was from the DFA (78.3%), followed by the CFA (11.7%), and the SFA (5%) [25]. As for the LCFA, in 83.3% of the cases, it arose from the DFA, in 6.7% from the CFA, and in 3.3% of cases, it was not apparent at all. Noticeably, in 1.7% of the cases, the DFA arose from the external iliac artery (EIA) with the LCFA originating from the DFA and the MCFA from the SFA. The Arabian study by Nasr et al. included 45 adult human cadavers and revealed that the DFA arose from the FA with the most common site of origin being the posterolateral one, followed by the posterior side [28]. As for the pattern of origin of the MCFA, this originated from the DFA in 60% of males and 57.5% of females, with less encountered types from the FA by a common trunk with the DFA, from the FA superior to the DFA and the SFA. In respect of the LCFA, this arose mostly from the DFA, whereas less frequent types were from the FA by a common stem with the DFA, from the FA above the DFA and the SFA. The range of the main distance of the DFA from the MIP was 25 -67 mm in males and 28 -70 in females, whereas the distance of the MCFA from the DFA was from 0 -42 mm in males and 0 -40 mm in females. The average distance of the LCFA from the DFA ranged from 0 -45 mm.
A CT evaluation in a 47-year-old male patient in France demonstrated that the MCFA emerged from the EIA, the LCFA came from the FA, and the DFA arose from the FA on the posteromedial side distally [29]. On the left side, the DFA originated from the medial side of the FA, whereas the LCFA came from the CFA at the same level.
Another case report regarding an 83-year-old Japanese male cadaver concluded that there was a common trunk of the deep circumflex iliac artery and part of the dLCFA at the transition from the EIA to the CFA under the inguinal ligament (IL) on the right side [30]. The MCFA and the remainder of the LCFA came from the DFA. As for the left limb, the MCFA, the inferior epigastric artery (IEA), and the obturator artery (OA) arose from the CFA, whereas the LCFA arose from the DFA.
Marcucci et al. published a case report describing a 47-year-old female in Italy in which examination revealed a complete transposition of the femoral artery and vein, where the CFA was medial to the CFA [31]. On the left thigh of the female cadaver of Caucasian origin in Athens, two DFAs were found being at a distance of 5.4 cm and 9.1 cm of the MIP without circumflex arteries [32].
In a 53-year-old Indian male cadaver, the LCFA coming from the DFA, traversed deep to the posterior division of the FN, instead of the anterior [33]. Another branch from the FA, distal to the LCFA, ran parallel to the LCFA, imitating the usual course of the latter. Lastly, a case report on a cadaveric dissection in Turkey described the posterolateral origin of the MCFA from the FA [34].
Regarding the variations in the ALT flap's vascular anatomy, a total of 277 CTAs were retrospectively analyzed in India by Lim et al. who concluded that the dLCFA, the branch that most frequently vascularizes the ALT flap, arose from the LCFA in 87.1% of cases [35]. Less common sources were the DFA, the CFA, and the SFA. The same study displayed that the oblique branch, present in 47% of extremities, contributed to the blood supply of the ALT flap. This arose from the tLCFA in 46.1% of cases, from the dLCFA or from the LCFA itself.
Another study conducted on 19 distally-based thigh flaps in 19 patients in China by Liu et al. illustrated that in eight out of the 19 cases, the source vessel of the ALT flap was the oblique branch [36]. In seven of these cases, it originated from the dLCFA and in one case from the tLCFA. A review of 110 ALT flaps in Taiwan by Lee et al. demonstrated that 69.1% of flaps were vascularized by the dLCFA, 9.1% from the tLCFA, and in 21.8% of the cases, the origin was dual [21].
A clinical study by Rozen et al. carried out on 44 patients who underwent ALT flap reconstruction showed that 16% of patients who underwent ALT flaps without preoperative CTA did not have any suitable perforators (> 1 mm) from which to harvest a flap supplied by the dLCFA [37]. In these cases, the ascending or transverse branch of the LCFA or MCFA were explored. Even if this was impossible, the contralateral leg was the next target.
A prospective intraoperative study of the ALT flap in Singapore by Wong et al. concluded that in 31 cases out of 88, there was a distinct oblique branch, whereas in 12 cases, the flap was based on this branch (Figures 2, 3) [38]. In one out of 88 cases, no sizable perforator was found, obliging surgeons to harvest a flap in the vicinity of the incision, in the opposite thigh, or even a different flap. A cadaveric study in Thailand by Boonrod et al. revealed that the dLCFA derived in 80% of cases from the LCFA, 12% from the CFA, and 8% from the DFA [39]. It also demonstrated that the LCFA gave off a single dLCFA in 76% of cases, a double in 6%, a triple in 2%, whereas a common dLCFA with single split-end branches was apparent in 16% of the cases.
Another study carried out in Taiwan by Lu et al. on 548 ALT flaps demonstrated that 55% of them required conversion to another flap due to small perforators (47% of the cases) or absent perforators (40% of the cases) [40].
A study by Seth et al., based on the CTA technique, depicted that the midpoint perforator was located in a surrounding distance of ± 2% of the midpoint of the total thigh-length only in 47% of cases [41]. The other perforators were at a distance of 52.7 mm proximal and 58.6 mm distal to the midpoint. It also displayed that the perforator vessel arose mostly from the LCFA. In 4% of cases, it derived from the SFA and in 1.1% from the CFA.
Kekatpure et al. published a study on 25 patients who underwent free ALT flaps and concluded that, in 21 cases, perforators arose from the dLCFA and, in four cases, from the oblique branch of the LCFA [42].
An Italian study by Ribuffo et al., based on the preoperative CTA technique, showed that the perforator arose from the dLCFA in 90.69% of the cases and from the tLCFA in 9.31% of the cases [43].
A case report of a 45-year-old man in Taiwan described an ALT flap with two perforators from the LCFA without any connection with the dLCFA [44].
Our review underlines the fact that the point at which the DFA branches from the FA is highly variant. Our results revealed that the most common site of origin of the DFA was the posterolateral wall of the FA. The second most frequent type of origin of the DFA was the posterior wall of the FA in accordance with two Indian studies, whereas a third Indian study illustrated the lateral wall as the second one. A variance was also noticed in the pattern of origin of the LCFA and the MCFA. Except for one study, in which the MCFA of the right limbs originated most frequently from the CFA, the majority of the left MCFAs in the same study and the MCFAs in the other studies, came mostly from the PFA. Similarly, the LCFA originated principally from the DFA, with the CFA being the second most frequent source of origin. As for the predominant site of origin, it was the medial for the MCFA and the lateral for the LCFA. The dLCFA was the main source of the perforators of the ALT flap in the majority of the cases described. This arose most often from the LCFA, but the DFA, the CFA, and the SFA represent other probable sources. A further consequential result was that, in some cases, an oblique branch was recognizable, either contributing to the vascularization of the flap or constituting its sole pedicle. The tLCFA, the dLCFA, and, less regularly, the LCFA were recorded as potential origins of this oblique branch.

Conclusions
The aim of our study was to collect and analyze all available information correlated to the anatomical characteristics of the DFA and its branches in order to ameliorate the current clinically pertinent knowledge. This information is vital for surgeons, interventional radiologists, and other medical professionals performing procedures in the femoral region. Furthermore, the use of ALT flaps has become an optimal option, especially for head and neck reconstruction. It is a multipurpose soft tissue flap that can be harvested as a fasciocutaneous or myocutaneous flap, whereas donor morbidity is strikingly minimal in spite of the availability of plenty of amounts of tissue. Notwithstanding that, the anatomical variations encountered may render this unreliable and risky. Preoperative CTA is an extremely reliable tool for displaying vascular anatomy and is superior to previous techniques, such as Doppler ultrasound. The use of CTA can contribute to the selection of the appropriate limb and perforator, thus enhancing flap design and operating outcomes. Excellent knowledge of anatomy can assist surgeons in surpassing uncertainties and safely harvest the flap. Several authors have demonstrated that in a significant number of patients, the skin of the ALT flap is supplied by a source other than the dLCFA, called the oblique branch. When present, this branch is of adequate size consisting of one artery and commonly two veins, thus permitting the acquisition of a viable and successful flap.