Most common cause of AVN of the hip is
**Core Concept**
Avascular necrosis (AVN) of the hip is a condition characterized by the death of bone tissue due to a lack of blood supply. It often results from traumatic events, certain medical conditions, or long-term use of corticosteroids.
**Why the Correct Answer is Right**
The most common cause of AVN of the hip is femoral neck fractures. This is because the blood supply to the femoral head is disrupted, leading to ischemia and subsequent necrosis of the bone tissue. The retinacular blood vessels, which are responsible for supplying blood to the femoral head, are often damaged in femoral neck fractures. This damage compromises the blood supply to the femoral head, increasing the risk of AVN.
**Why Each Wrong Option is Incorrect**
* **Option A:** Osteonecrosis secondary to systemic lupus erythematosus (SLE) is a rare cause of AVN of the hip. While SLE can increase the risk of AVN, it is not the most common cause.
* **Option B:** Traumatic dislocation of the hip joint can also lead to AVN, but it is less common than femoral neck fractures.
* **Option C:** Corticosteroid use is a known risk factor for AVN, but it is not the most common cause of AVN of the hip.
**Clinical Pearl / High-Yield Fact**
Femoral neck fractures are a significant risk factor for AVN of the hip, and early recognition and treatment are crucial to prevent long-term complications.
**Correct Answer: D. Femoral neck fractures.**