Avascular necrosis of head of femur occurs commonly at :
**Core Concept**
Avascular necrosis (AVN) of the femoral head is a condition characterized by the death of bone tissue due to a lack of blood supply. This occurs when the blood vessels that supply the femoral head are disrupted, leading to ischemia and subsequent necrosis.
**Why the Correct Answer is Right**
The most common location for AVN of the femoral head is the weight-bearing area, specifically the superior and medial aspects of the femoral head. This is due to the unique anatomy of the femoral head, which receives its blood supply primarily from the medial and superior retinacular branches of the medial circumflex femoral artery. These vessels are susceptible to injury, particularly in the setting of femoral neck fractures or hip dislocations, which can disrupt the blood supply to the femoral head. The resulting ischemia can lead to AVN, especially in the weight-bearing areas.
**Why Each Wrong Option is Incorrect**
**Option A:** Not a commonly affected area.
**Option B:** While the intertrochanteric region can be affected by AVN, it is not the most common location.
**Option C:** The subchondral bone is a common site for AVN, but it is not the most frequently affected area.
**Clinical Pearl / High-Yield Fact**
Remember that AVN of the femoral head often presents with a "crescent sign" on radiographs, which is a characteristic appearance of the subchondral fracture line.
**Correct Answer:** None
Correct Answer: .