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Avascular Necrosis (AVN)

What is avascular necrosis?

Avascular necrosis or AVN, also called osteonecrosis, is a condition that happens when parts of bone die because of poor blood supply.

AVN can occur as a side effect of some cancers or cancer treatments. It can also occur with serious illnesses such as sickle cell disease.

AVN can affect one bone. Or it can affect many bones. AVN can cause pain and affect joint function in the:

  • Knees
  • Hips
  • Shoulders
  • Ankles

Avascular necrosis may be mild. The condition may also be severe. It can cause pain and long-term disability.

A graphic explaining the term avascular necrosis. "A" means without, "vascular" means blood supply, and "necrosis" means death of cells or body tissue. Avascular necrosis / Osteonecrosis means the breakdown of bone tissue caused by poor blood supply.

Avascular necrosis and cancer

Avascular necrosis (AVN) is a common side effect of leukemia and lymphoma therapies.

Up to half of children treated for acute lymphoblastic leukemia (ALL) have some degree of AVN. Children who have received a bone marrow transplant have some degree of AVN. Children who received a bone marrow transplant are also at high risk of developing AVN.

AVN can occurr at the ends of long bones, such as the femoral head of the femur. Here, the femure bone structure is labeled, indentifying the articular proximal epiphysis, metaphysis, diaphysis, and distal epiphysis.

In pediatric cancer patients, AVN is often seen near the ends of long bones, an area called the epiphysis.

AVN can happen in any bone. But it is usually seen at the end of long bones in pediatric cancer patients. This is an area called the epiphysis.

Damage to bones and joints can lead to long-term problems including joint collapse and arthritis.

Older children and teens are more likely to develop AVN during cancer treatment. It is less common in children under 10.

Early stages of AVN can be hard to detect. Your child may not have pain or other symptoms until bone damage is severe.

AVN management depends on pain and the degree of bone damage. Pain management and physical therapy can help patients with symptoms.

Some patients may need surgery to improve blood flow and relieve pressure within the bone. If there is severe damage or joint collapse, your child may eventually need a joint replacement.

Avascular necrosis and sickle cell disease

People with sickle cell disease have red blood cells that are sticky and shaped like a banana. Normal red blood cells are round and flexible.

Sickle cells can block blood flow in small blood vessels of the body. When blood flow is blocked in vessels that supply bone, the bone does not get enough oxygen. That can cause bone tissue to die.

Avascular necrosis results from losing blood supply to bone in the joint. This loss of blood causes narrowing of the joint and collapse of the bone.

Avascular necrosis can affect a single joint or more than one joint.

Symptoms of avascular necrosis

Some patients may not have any symptoms at first. But as AVN progresses, they can have joint and bone pain.

If your child has AVN, you may notice them:

  • Limping or changing their gait
  • Avoiding the affected joint
  • Having a reduced range of motion
  • Experiencing pain (may come and go or be constant)
  • Experiencing stiffness or “catching” in a joint
  • Having problems walking up or down stairs

AVN can sometimes result in collapse of bone. And the pain may suddenly worsen.

Pain and disability usually depend on:

  • What areas of the bone are affected
  • How much AVN is present
  • How quickly damage progresses
  • How well the bone can repair itself

Pain is not a reliable indicator of how severe AVN is. Small areas of AVN can be very painful. Other patients may not have pain, even when areas of AVN are very large.

Causes of avascular necrosis 

Avascular necrosis is a complex condition that can be based on many factors. But the main cause of AVN is a loss of blood supply to the bone. This can happen during cancer treatment or because of conditions such as sickle cell disease.

When blood vessels are too small or become damaged or clogged, nutrients and oxygen cannot get to the bone. Bone cells begin to die.

Your care team can help you understand more about what might cause AVN in your child’s specific situation.

Diagnosis of avascular necrosis

Your child’s care team can use imaging tests are used to identify areas of AVN. These include:

 X-rays do not always show early stages of AVN. But they do show later stages of AVN. 

Treatment of avascular necrosis

The main goals of treatment are pain control, maintaining joint function, and preventing further damage. 

Your child’s care team will create a care plan to help manage AVN. Doctors consider:

  • Your child’s age
  • Your child’s overall health
  • Any treatment schedule for other illnesses
  • AVN stage
  • Bones and joints affected
  • Pain severity

Ways you can help your child manage avascular necrosis include:

  • Ensuring they take pain medicines and medicines to reduce swelling (anti-inflammatory medicines) as prescribed.
  • Let your child’s care team know if your child has joint pain or limping.
  • Follow instructions from your child’s physical therapist if physical therapy is part of your child’s treatment plan.
  • Have the joint examined and treated by an orthopedic (bone) surgeon if your child’s care team recommends it.

Surgery for avascular necrosis

In some cases, surgery might be used to treat avascular necrosis. These options can include:

  • Core decompression – Core decompression removes the inner layer of bone. This may reduce pressure within the bone and create an open area for new blood vessels to grow. Sometimes a piece of healthy bone with good blood vessels is put into this area to speed up the process. This procedure works best in the earliest stages of AVN.
  • Bone graft – Surgery to treat AVN may include a bone graft to replace and rebuild damaged bone. This involves transplanting healthy bone tissue from another part of the body or from a donor. Artificial material may also be used. If cartilage is damaged, the graft may include both bone and cartilage. In some cases, blood vessels are transplanted along with the bone tissue. In AVN, a bone graft is most often used along with core decompression.
  • Osteotomy – An osteotomy involves taking out a piece of bone to reposition the bone. This allows the area with blocked blood vessels to bear less weight than a healthy area next to it.
  • Arthroplasty – Arthroplasty is sometimes called a joint replacement. The diseased bone is removed and replaced with artificial parts.
Some patients may need surgery, like joint replacement, to manage AVN.

Some patients may need surgery to manage AVN. Joint replacement involves removing the damaged bone and replacing it with an artificial joint.

Complementary or integrative therapies

Your child may find help from mind-body therapies such as massage, acupuncture, biofeedback, and relaxation techniques.

Specific techniques can help your child:

  • Manage pain
  • Reduce stress
  • Decrease muscle tension
  • Improve blood flow

Talk to your child’s care team before trying any new therapy. They will ensure that it is safe and fits well with your child’s needs.

Key points about avascular necrosis

  • Avascular necrosis occurs when areas of bone die because of poor blood supply.
  • Children with sickle cell disease are at risk for developing avascular necrosis.
  • Children undergoing certain types of cancer treatment are at risk for developing avascular necrosis.
  • Imaging tests can help diagnose avascular necrosis.
  • If your child develops avascular necrosis, follow the treatment plan their care team recommends

Reviewed: September 2022