What is Avascular Necrosis?

What Is Avascular Necrosis?

When a bone dies due to insufficient blood flow, it is known as avascular necrosis (AVN). The ball in the ball and socket joint of the hip is called the femoral head. The femur or thigh bone is fitted into the cup-shaped socket of the pelvis. The joint is held together by muscles, ligaments and tendons. Due to inadequate blood flow, the bone dies, and the joint becomes weak, leading to bone necrosis. Osteonecrosis, Aseptic necrosis and Ischemic necrosis are other terms used for avascular necrosis.

Causes and Risk Factors

AVN is common in long bones. Unlike various other bone conditions, AVN is seen mainly in men between 40 and 50. Other causes of AVN are as follows-

  • Major impact injuries from an accident or sport activity
  • Hip fracture or hip dislocation
  • Inflammation
  • Blood clots
  • In children, Legg-calve-Perthes disease

The risk factors of AVN include-

  • Sickle cell disease
  • Gout
  • Lupus
  • Prolonged use of corticosteroids
  • Heavy alcohol consumption

Injuries and diseases, if left untreated, can cause necrosis as well.

Complications and Prevention

If AVN is not treated in time, it can lead to tissue death in the hip joint and eventually cause the bone to collapse. In addition, drugs like corticosteroids can worsen the AVN. If you have been taking corticosteroids for a while now, talk to your doctor about the other alternatives to lower the possibility of AVN. Maintaining strength and flexibility is the best preventive solution. Ensure proper warm-up before working out and add in some strength exercises to the routine.

How is AVN caused?

In avascular necrosis, the hip causes the femoral head to flatten. The flatten ball no longer fits into the socket. Thus, there is wear and tear of the hip joint that leads to osteoarthritis and pain. How severe the AVN is, depends on the total volume, damage due to the abnormal tissue changes, and position of the surface of the femoral head.

Initially, pain is felt only when weight is applied to the hip. However, as the AVN advances, the pain can become constant. The pain is felt in the buttocks, groin area or the front of the thigh. In addition, symptoms like limping or stiff hip might affect the pain.


Your profession and medical history are the two primary requirements to diagnose AVN. The reason is that certain professions put you at an increased risk of suffering from AVN. After the doctor has gathered the needed information, they will suggest an X-Ray. If the disease is in its initial stages, the X-Ray might appear normal despite the pain. In such cases, a CT Scan is required. It goes beyond the pain to find the cause. If AVN is the cause, then a CT Scan might as well help in identifying the stage.

  • CT Scan uses a massive camera to take bone images. If there is no blood supply to a region, it appears as a blank spot in the film.
  • MRI is used for a more detailed diagnosis. It uses magnetic waves to capture several images of the hip.

Since MRI is very sensitive, it provides minute details that identify the root cause of a disease. Thus, to get a proper diagnosis, the doctors often recommend X-Rays, CT scans and MRIs.