What is Avascular Necrosis of the Hip?

Avascular necrosis of the hip, or osteonecrosis of the hip is a condition where the blood supply to the head of the thighbone is cut off. The head of the thighbone, or femur looks like a ball and fits into a socket in the pelvis.

Bone is living tissue and needs a blood supply, and when that supply is cut off the bone begins to die and undergo necrosis. If the condition is not treated, it can lead to the destruction of the bone and the cartilage that covers it.

What Causes Avascular Necrosis of the Hip?
Sometimes doctors don’t know why the blood supply to the head of the thighbone is cut off, but there are risk factors that can make it more likely. In some cases, the person has suffered an injury to their hip that damages blood vessels in the area.

Alcoholism can also contribute to the disorder by causing deposits of fat to settle in the person’s blood vessels. This raises the levels of a hormone called cortisone, which compromises the flow of blood to the bone. Other reasons are the use of corticosteroids, which are given to people who have such disease as rheumatoid arthritis or asthma. Doctors don’t know why taking corticosteroids can lead to osteonecrosis of the hip.

The disorder is also connected with sickle cell anemia, lupus, Crohn’s disease, embolism, vasculitis and even “the bends,” a painful condition that afflicts divers that come up too quickly from deep dives.

Symptoms
Symptoms come on gradually. At first, the person feels a pain in their hip. The pain spreads to their groin or their buttock, and they find it harder and harder to put weight on the leg served by their thighbone. Trying to move their hip is also painful. These symptoms can take months to develop.

Diagnosis
The doctor diagnoses avascular necrosis of the hip through a physical examination and imaging tests such as X-rays and MRI scans. An MRI can show osteonecrosis developing before the patient develops any symptoms.

How Osteonecrosis of the Hip is Treated
Doctors may prescribe anti-inflammatory drugs such as ibuprofen for the pain, and physical therapists can help patients stay mobile, but in the end, surgery is the best treatment for osteonecrosis of the hip. The earlier the condition is diagnosed, the more likely that the patient’s natural hip can be preserved.

One type of surgery is core decompression. The surgeon drills one large or a number of small holes into the ball of the hip. This both creates new channels for blood vessels and removes the pressure on the bone. If this procedure is performed early in the disease, it may be all that’s needed to preserve the hip.

In another surgery, bone and cartilage from another part of the body or from a donor is grafted onto the bone. In a vascularized fibula graft, a piece of bone from the patient’s leg plus its blood supply is grafted onto the thigh bone.

If the disease is advanced, total hip replacement may be the one thing that preserves the patient’s mobility.