Introduction

The femoral artery is a large vessel that provides oxygenated blood to lower extremity structures and in part to the anterior abdominal wall. The common femoral artery arises as a continuation of the external iliac artery after it passes under the inguinal ligament. The femoral artery, vein, and nerve all exist in the anterior region of the thigh known as the femoral triangle, just inferior to the inguinal ligament. Within the femoral triangle, the anatomical relationship from medial to lateral is femoral vein, common femoral artery, and femoral nerve. The artery and vein are both contained within the femoral sheath while the nerve is not.[1] The common femoral artery gives off the deep femoral branch and continues as the superficial femoral artery. The superficial femoral artery continues distally to the level of the adductor hiatus where it terminates as the popliteal artery. The deep femoral artery terminates as perforating arteries in the thigh.[2] 

 The femoral artery is clinically significant because it is a frequent site of peripheral arterial disease complications as well as an access point for many endovascular procedures.

Structure and Function

The common femoral artery forms as a continuation of the external iliac artery below the level of the inguinal ligament. It is found just medial to the midpoint of the inguinal ligament in the inguinal crease region. The two bony landmarks useful for identifying the inguinal ligament are the anterior superior iliac spine and pubic symphysis. The average common femoral artery is approximately 4 cm in length and lies just anterior to the femoral head. Its length and diameter are quite variable depending on characteristics such as height, weight, sex and ethnicity[3]. Branches arising from the common femoral artery include superficial epigastric artery, superficial circumflex artery, and external pudendal artery.[4]

Distal to these smaller branches, the common femoral artery bifurcates into the deep femoral (or profunda femoris) and superficial femoral artery.[5]

The superficial femoral artery plays a crucial role in delivering oxygenated blood to the entire lower leg. Before entering the adductor canal, it gives off the descending genicular artery that supplies part of the knee.[6] As the superficial femoral artery traverses the adductor canal, it gives off minor branches to the muscles of the thigh. Once it emerges from the adductor hiatus, its name changes to the popliteal artery which provides oxygen-rich blood to the rest of the knee compartment. The femoral vein courses posterior to the femoral artery through the adductor canal.

The deep femoral artery gives rise to medial and lateral circumflex arteries that supply the femur and hip region before it dives deep into the thigh compartment and terminates as perforating deep tissue branches.[7]

Embryology

At the 6-mm stage, the dorsal root of the umbilical artery gives rise to the axial artery which provides several branches to the embryologic foot. A distinct femoral artery entering the leg is present at the 14-mm stage with communications to the axial and sciatic artery. The sciatic artery regresses around 22 mm, and the femoral artery is the sole supplier of blood to the lower limb. The vasculature establishes its adult pattern by the 8-week of embryologic development. Nerves supplying the lower limb develop from the medial and dorsal cord to supply the ventral and dorsal muscles, respectively.[8]

Blood Supply and Lymphatics

The deep veins of the leg are typically named in accordance with the artery and drain the musculature. The superficial veins are responsible for draining the cutaneous circulation. All of the superficial veins eventually drain into the saphenous system which communicates with the common femoral vein. The femoral vein courses posterior to the femoral artery through the adductor canal.[9]

The deep inguinal node of Cloquet mediates the lymphatic drainage of the penis, clitoris and fatty connective tissue in the inguinal region. The primary lymphatic chain that drains the lower extremities and groin is the most medially located structure within the femoral triangle.[9]

Nerves

The ventral rami of L2, L3, and L4 give rise to the femoral nerve which then descends inferiorly and passes posterior to the inguinal ligament. In the femoral triangle, the femoral nerve is located lateral to the femoral artery and exterior to the femoral sheath.[10] The femoral nerve delivers motor innervation to the anterior muscles of the thigh (quadriceps, sartorius, iliacus, and pectineus). It also supplies cutaneous sensation to the anterior thigh and anteromedial aspect of the leg.[6] The surgeon must exercise care to avoid injuring the femoral nerve while performing femoral artery percutaneous procedures.[8]

Muscles

After branching off of the deep femoral artery, the medial circumflex artery runs along the posterior side of the femur and supplies blood to the thigh adductors (longus, magnus, and brevis), gracilis, pectineus as well as the femoral head and neck.[5] The lateral circumflex courses laterally and supplies oxygenated blood to the major knee extensor group including vastus lateralis, vastus intermedius, and rectus femoris. Vastus medialis is supplied in part by both the superficial femoral artery and deep femoral artery. The perforating arteries of the deep femoral artery supply the four hamstring muscles (semitendinosus, semimembranosus, short and long head of biceps. After exiting the adductor canal, the superficial femoral artery continues distally as the popliteal artery which serves the entire calf and foot with oxygen-rich blood.[10]

Physiologic Variants

Although many benign variants of the femoral artery exist, there are some that are considered to be rare and potentially dangerous to the patient. The origins of smaller arteries off of the femoral artery can be highly variable. Less common abnormalities include a duplicated or absent deep femoral artery, lateral and medial circumflex arteries most originating from the common or superficial femoral artery instead of the deep femoral. The clinical significance of this variant is that the common femoral artery may appear to trifurcate instead of bifurcate.[5] The precise level of the common femoral artery bifurcation may vary from person to person and often does not align with the inguinal crease. Ultrasound examination is routinely used for safe and effective vascular access.[1] Another potential abnormality of the femoral artery is the presence of a persistent sciatic artery. It occurs when the embryonic vessel fails to regress and thus remains the dominant feeding vessel to the lower extremity. Serious limb ischemia complications may arise due to higher rates of an aneurysm and thromboembolic complications in this unusual variant.[11] Finally, an even more unusual variant is the presence of duplicate superficial femoral arteries and knowledge of this plays a vital role in preprocedural planning.[12] 

Surgical Considerations

The region of the anterior thigh that lies just inferior to the inguinal ligament is termed the femoral triangle. Within the femoral triangle, there is a discrete organization, and thorough understanding of these anatomical relationships are necessary to avoid inadvertent injury to the femoral artery, vein, and nerve during procedures such as hernia repairs and nerve blocks.  

During percutaneous vascular access procedures, the common femoral artery is often desirable as an access point because it is suitable for large-diameter catheters and sheaths to be placed which allows for a wide variety of endovascular procedures. It is essential to access the common femoral artery just superior to the bifurcation of the superficial and deep branches to reduce complications. Although the inguinal crease is frequently used as an initial landmark, ultrasound guidance is more precise when determining the relevant anatomy, specifically the common femoral artery bifurcation and inferior epigastric artery. Arteriotomy site should be between the bifurcation and the inferior epigastric artery. Fluoroscopy is also useful to identify the femoral head which is often an anatomical landmark for accessing the common femoral artery.[2][13]

Endovascular intervention is common in patients with clinically significant peripheral arterial disease. The atherosclerotic burden most afflicts the superficial femoral artery, common femoral artery and/or the popliteal artery. Patients with heavily calcified arteries exhibiting clinical signs and symptoms may require endovascular angioplasty (ballooning) with or without stenting to improve distal blood flow. If an artery is unable to be repaired endovascularly, vascular surgical consult may be necessary for an arterial bypass procedure.[12]

Clinical Significance

In individuals with peripheral arterial disease (PAD) the most common sites of involvement are the superficial femoral artery and the common femoral artery. Symptoms that indicate femoral artery disease may include claudication in the thighs and calves, cold, discolored extremities, poor wound healing below the lesion, change in sensation, and in end-stage disease, gangrene or necrosis of the digits. Chronic health conditions that increase a patient’s risk of PAD include age, obesity, diabetes, hypertension, hyperlipidemia, coronary atherosclerotic disease, vasculitis, sedentary lifestyle, and smoking. It is worth noting that the absence of these risk factors does not preclude a patient from having PAD.[10]

 In instances where the common and superficial femoral arteries are chronically occluded, extensive collaterals may be present between the deep femoral artery, and thus distal blood flow is more robust than expected.[14] Prior to any percutaneous endovascular intervention, a comprehensive clinical evaluation including palpating pulses, visual evaluation of the extremity, Doppler ultrasound, ankle-brachial indices, and patient symptoms should take place. If warranted, a CT-angiogram (CTA) of the lower extremities may be performed to better evaluate the extent of atherosclerotic disease and assist in further management.[10]

Other Issues

The course of the common femoral artery over the femoral head is important because it acts as a hard surface to which manual pressure can be effectively applied. Accessing more superiorly or inferiorly can make hemostasis difficult to achieve and lead to greater complications. Complications of femoral artery access include hematomas, pseudoaneurysms, injury to the femoral nerve, retroperitoneal hemorrhage, arteriovenous fistulas, and distal embolization of plaque. Hematomas and hemorrhage may occur with inadequate thrombosis of the arteriotomy and present in the groin or flank.[3] The level of the inferior epigastric artery is generally accepted as the superior boundary of potential arteriotomy sites. More superior than this puts the patient at high risk of bleeding into the retroperitoneal space. Alternatively, arteriotomies of the superficial femoral artery are at increased risk of avoidable complications.[15][16] Checking for complications post-procedurally and educating the patient about concerning signs for which they should seek immediate medical attention is of utmost importance.