The femoral head is the ball-shaped top of the thigh bone, or femur. It fits inside a socket-shaped hollow in the hip bone, known as the acetabulum, and the two parts make up the hip joint. Avascular necrosis of the femoral head is a condition in which the blood supply to the femoral head is lost, resulting in osteonecrosis, or death of bone cells. Causes of the condition can include steroids and other drugs, alcoholism and accidental injury. While medication and a combination of rest and stretching exercises can help with symptoms, surgical treatment is usually required to treat the condition effectively.
Blood is supplied to the femoral head through arteries which travel along the femoral neck, a narrow section of bone connecting the femoral head to the shaft of the femur. As this is the only blood supply, if the flow is disrupted, the bone of the femoral head dies and its rounded structure may collapse and flatten. Once the hip joint no longer fits together smoothly, the joint surfaces can become worn and joint deterioration may set in.
Avascular necrosis of the femoral head typically leads to pain, which is experienced when weight is placed on the hip. Most often, the pain is felt in the groin, but it can also be felt in the buttock or thigh. If femoral head necrosis progresses, hip pain may occur even when the person is resting, and it may become difficult to walk, with stiffness and a limp developing in time. Fractures of the femoral neck can cause avascular necrosis, as can hip dislocation. Conditions such as alcoholism and diabetes may damage the blood supply to the femoral head, as may taking steroids at high doses or for a long time.
If avascular necrosis of the femoral head has not progressed too far, and the head of the femur has not collapsed, the most common treatment is a surgical procedure called core decompression. During the core decompression operation, the surgeon drills through the femoral neck, creating channels through which new blood vessels can grow and form a blood supply for the head. The procedure can be carried out using minimally invasive techniques, often known as keyhole surgery, and does not require a stay in the hospital.
Core decompression usually prevents progression and relieves any pain due to avascular necrosis of the femoral head. In cases where the condition has advanced and the hip joint has deteriorated, arthritis usually develops. Then, the recommended treatment is to remove the femoral head and neck, together with the acetabulum, and insert artificial hip parts instead. This operation is known as a total hip replacement.