Avascular necrosis (AVN) of the femoral head is a condition characterized by the loss of blood supply to bone, leading to bone death and potential collapse of the hip joint. Causes include traumatic injuries and steroid use, while symptoms encompass pain and stiffness in the hip. Diagnosis typically involves imaging techniques like X-rays and MRIs, with treatment options ranging from medical management to surgical interventions such as core decompression or total hip replacement, depending on the disease stage.