Avascular Necrosis

MRIs on the left side show Avascular Necrosis (AVN) of the femoral head before-collapse (top left) and after-collapse stage (bottom left).
The x-rays on the right show hip preservation surgery (top right), and
bilateral total hip replacement Dr. Sami performed at the same time using the anterior approach technique (bottom right).

What is it?
Bone is a living tissue that relies on its blood supply to survive. The blood supply to the ball bony portion of the hip joint comes through the neck of the femur. Damage to this blood supply can cause the death of the ball of the hip joint, which is called Avascular necrosis (AVN). Another name of AVN is osteonecrosis (which means bone death).

Cause
Anything that damages the blood supply to the hip can cause AVN. Some of the reasons we see in Ethiopia include:
• Direct trauma to the blood supply in cases of hip area fractures, or dislocation of the ball out of the socket.
It takes months to years for AVN to show up following trauma.
• Some medical treatments: steroids; chemo, and radiation therapy (used to treat cancer); organ transplantation.
• Smoking
• Excessive Alcohol use
• HIV
• Gout
• Leukemia

Symptoms
Pain is usually the earliest sign of AVN. It can be felt in the groin area, the buttock area, and down the front of the thigh. It gets worse during walking resulting in limp and progressive shortening of the leg. The hip feels stiff and eventually, the pain will also be present at rest and may even interfere with sleep. It is usually seen on both hips, but sometimes, especially when AVN develops following trauma it can occur on one hip.

Diagnosis
The condition is identified after we conduct an in-depth evaluation of the problem and possible risk factors followed by physical examination and imaging.
In the early stages (stages 1 & 2), it may not show up on X-rays, so MRI is important to pick early disease before it is too late to salvage the natural hip joint.

Treatment
The treatment of AVN depends on how far along the problem is and your symptoms.

The things we take into consideration include:
• Age
• Activity level
• General health
• Life expectancy
• The cause or identified risk factor
• Stage of the disease

Non Surgical options:
Anti pain medications help ease the pain.
Bisphosphonate (medication used for the treatment of osteoporosis) has been shown to reduce the risk of femoral head collapse in patients with avascular necrosis.

Surgical options:

Hip preservation

The picture shows how core decompression is done.

When AVN is picked before the ball collapses (in cases of stages 1 & 2), we have a surgical option to try to increase the blood supply to the femoral head. The surgery involved a stab incision on the lateral aspect of the hip. the hip is then drilled to get to the dead part of the ball (called core decompression). This is followed by the installation of stem cells to the dead part of the ball.

Decompression:

(1) creates a channel for new blood vessels to form into the area that lacks blood supply, and

(2) it relieves some of the pressure inside the bone of the femoral head. Relieving this pressure help decrease the pain patients experience from AVN.

The live cells harvested from a normal bone have the potential to facilitate new bone formation replacing the dead ones.

Dr. Sami performs outpatient percutaneous core decompression and infiltration of patients’ own bone marrow in the dead part of the bone. Patients’ go home the same day of the procedure and will be on crutches for 6weeks.

Artificial hip replacement
When AVN is advanced (stage 3 or more), it is not any different from the worn-out hip (osteoarthritis). Total Hip Replacement (THR) will be the lasting solution for it.


Dr. Sami performs minimal invasive anterior approach total hip replacement surgery. This technique makes conducting bilateral hip replacements at the same time a possibility (as shown in the example above). This has revolutionized the way we address advanced AVN disease, as AVN is often a bilateral hip disease.

See Dr. Sami’s video below on anterior approach hip replacement done for a young man with bilateral AVN.

Compiled and written on June, 2021. By Dr. Samuel Hailu.

*Disclaimer:*The information contained herein is for educational purposes only. This should NOT be used in place of a visit with your healthcare provider, nor should you disregard the advice of your healthcare provider because of any information you read on this topic.