In the setting of intracapsular femoral neck fracture, which artery is most at risk for avascular necrosis?

In the setting of intracapsular femoral neck fracture, which artery is most at risk for avascular necrosis?

• A. Lateral femoral circumflex artery
• B. Inferior gluteal artery
• C. Medial femoral circumflex artery
• D. Obturator artery

Answer: (C)

The key idea is how the femoral head receives its blood supply and what a fracture in the joint capsule does to it. The femoral head is mainly fed by branches of the medial femoral circumflex artery, which give rise to the retinacular arteries that travel up along the femoral neck under the capsule to the head. In an intracapsular fracture, these retinacular vessels are the ones most likely to be torn or kinked, so the blood flow to the head can be severely compromised, leading to avascular necrosis. The artery of the ligamentum teres, coming from the obturator artery, contributes only a small amount of blood in adults and is usually not enough to sustain the head if the main supply is disrupted. The lateral femoral circumflex artery supplies the femoral neck and surrounding muscles more than the head itself, and the inferior gluteal artery supports other hip structures rather than being the primary source to the femoral head. So, the medial femoral circumflex artery is the vessel most at risk in an intracapsular femoral neck fracture because its retinacular branches provide the essential blood flow to the femoral head.

The key idea is how the femoral head receives its blood supply and what a fracture in the joint capsule does to it. The femoral head is mainly fed by branches of the medial femoral circumflex artery, which give rise to the retinacular arteries that travel up along the femoral neck under the capsule to the head. In an intracapsular fracture, these retinacular vessels are the ones most likely to be torn or kinked, so the blood flow to the head can be severely compromised, leading to avascular necrosis.

The artery of the ligamentum teres, coming from the obturator artery, contributes only a small amount of blood in adults and is usually not enough to sustain the head if the main supply is disrupted. The lateral femoral circumflex artery supplies the femoral neck and surrounding muscles more than the head itself, and the inferior gluteal artery supports other hip structures rather than being the primary source to the femoral head.

So, the medial femoral circumflex artery is the vessel most at risk in an intracapsular femoral neck fracture because its retinacular branches provide the essential blood flow to the femoral head.