What is the blood supply to the femur?

Blood Supply of the Femur

The femur receives its primary blood supply from the deep branch of the medial femoral circumflex artery (MFCA), the profunda femoris artery (PFA) and its branches, with additional contributions from the lateral circumflex femoral artery (LCFA) and nutrient arteries. 1, 2

Arterial Supply to the Femur

Proximal Femur (Femoral Head and Neck)

• The deep branch of the MFCA provides the primary blood supply to the femoral head, making it critically important in preventing avascular necrosis after hip fractures or dislocations 1, 3
• The deep branch of the MFCA follows a consistent extracapsular course, crossing posterior to the tendon of obturator externus and anterior to the conjoint tendon before perforating the joint capsule at the level of gemellus superior 1
• Once intracapsular, it divides into 2-4 subsynovial retinacular vessels that supply the femoral head 1
• The postero-inferior nutrient artery (also from MFCA) contributes to femoral head blood supply 3
• The piriformis branch of the inferior gluteal artery provides additional blood supply to the femoral head 3

Femoral Shaft

• The profunda femoris artery (PFA) is the principal source of blood supply to the femoral shaft 4, 2
• The PFA typically originates from the posterolateral surface of the common femoral artery at a mean distance of 3.56-5.19 cm from the mid-inguinal point 4, 5
• The PFA gives rise to perforating branches that penetrate the femoral shaft to provide endosteal blood supply 4
• The nutrient artery to the femoral shaft typically arises from the PFA or one of its perforating branches 4

Circumflex Arteries

• The medial circumflex femoral artery (MCFA) originates from the PFA in 40-60% of cases and directly from the femoral artery in 35-50% of cases 4, 5
• The lateral circumflex femoral artery (LCFA) arises from the PFA in 70-80% of cases and from the common femoral artery in 20-25% of cases 4, 5
• The MCFA has an average diameter of 2.9-3.09 cm, while the LCFA has an average diameter of 2.8-3.71 cm 5

Clinical Significance

Surgical Considerations

• During posterior approaches to the hip, the short external rotators are often divided, which can damage the deep branch of the MCFA and potentially lead to avascular necrosis of the femoral head 1
• The obturator externus muscle protects the deep branch of the MCFA during hip dislocation, highlighting its importance in surgical planning 1
• Understanding the variable anatomy of the PFA and its branches is crucial for surgeons performing procedures in the femoral region to avoid vascular complications 4, 2

Collateral Circulation

• In cases of superficial femoral artery occlusion, the PFA forms an effective collateral pathway between the ileo-femoral segment and the popliteal artery 4
• The size and patency of these collateral pathways can determine the risk of limb loss following vascular interventions 2
• The PFA supplies important collateral branches to both the ipsilateral internal iliac artery and the distal superficial femoral artery 2

Anatomical Variations

• Six PFA, 5 LCFA, and 5 MCFA variations have been identified, with the 5 most common combinations accounting for 56.1% of cases 2
• The mean diameters of the PFA are 6.9 mm in males and 6.1 mm in females, showing significant gender differences 2
• Absence of the PFA has been reported in approximately 5% of cases 4

Vascular Imaging and Assessment

• CT angiography can effectively visualize the three main arteries supplying the femoral head: the deep branch of the MCFA, the postero-inferior nutrient artery, and the piriformis branch of the inferior gluteal artery 3
• Ultrasound imaging with a linear array vascular probe (6-10 MHz) can be used to evaluate the femoral vessels, with the common femoral vein typically located medial to the artery immediately inferior to the inguinal ligament 6
• The superficial femoral artery continues as the popliteal artery as it passes through the adductor canal 6

Understanding the blood supply of the femur is essential for surgical approaches to the hip and femur, management of fractures, and interventional procedures to minimize the risk of avascular necrosis and other vascular complications.