Avascular necrosis (also called AVN or osteonecrosis) is a condition that happens when parts of bone die because of poor blood supply. AVN can happen as a side effect of some cancers or cancer treatments. It can also occur with 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. Common places AVN occurs include the:
Knees
Hips
Shoulders
Ankles
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 (the joint is no longer in its typical smooth shape), your child may eventually need a joint replacement.
Symptoms of avascular necrosis
Early stages of AVN can be hard to detect. Your child may not have pain or other symptoms until bone damage is severe. But as AVN progresses, they can have joint and bone pain.
Signs and symptoms of AVN may include:
Limp or change in their gait (walking pattern)
Not using the affected joint
Reduced range of motion
Pain that may come and go or be constant
Stiffness or “catching” in a joint
Problems walking up or down stairs
Pain and disability usually depend on:
What areas of the bone are affected
How much AVN is present
How quickly damage happens
How well the bone repairs itself
Pain is not always a good indicator of how severe the AVN is. Small areas of AVN can be very painful for some patients. For other patients, large areas of AVN may not be painful at all. AVN can sometimes result in the collapse of bone and pain may suddenly worsen.
Causes of avascular necrosis
Avascular necrosis is a complex condition that can be due to many factors. The main cause of AVN is a loss of blood supply to the bone.
When blood vessels are too small or become damaged or clogged, nutrients and oxygen cannot get to the bone. When this happens, bone cells begin to die. The bone becomes weak and can lead to bone collapse.
Your care team can help you understand your child’s risk.
Avascular necrosis (also known as AVN or osteonecrosis) occurs when areas of bone weaken because of poor blood supply.
AVN can happen in any bone. In pediatric cancer patients, it is usually seen at the end of long bones. This is an area called the epiphysis.
Older children and teens are more likely to develop AVN during cancer treatment. It is less common in children under 10 years of age.
Avascular necrosis and sickle cell disease
Normal red blood cells are round and flexible. People with sickle cell disease have red blood cells that are sticky and shaped like a banana. These 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. The lack of blood flow can cause bone tissue to die.
Other risk factors related to avascular necrosis include diabetes, HIV, osteoporosis, injury, and certain medications.
Diagnosis of avascular necrosis
Your care team can use imaging tests to detect AVN. Imaging tests include:
X-rays do not always show early stages of AVN. But they do show later stages of AVN.
Treatment of avascular necrosis
AVN management depends on pain symptoms and the degree of bone damage. The main goals of treatment for AVN are pain control, maintaining joint function, and preventing further damage.
Your child’s care team will create a care plan to help manage AVN. They will consider:
Mobility aids or assistive devices to take weight off the affected joint
Rest and avoiding activities that put extra stress on the joint
Surgery for avascular necrosis
Some patients may need surgery to improve blood flow and relieve pressure within the bone. 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.
Joint replacement (arthroplasty): Joint replacement involves removing the damaged bone and replacing it with an artificial joint.
Talk to your care team before trying any new therapy to make sure it is safe for your child.
Prognosis for avascular necrosis
Avascular necrosis can range from mild to severe. It can cause pain and affect movement and ability to do daily activities. Damage to bones and joints can lead to long-term problems including joint collapse and arthritis.
Ways to help manage avascular necrosis include:
Let your care team know if your child has joint pain or limping or if symptoms get worse.
Give pain medicines as prescribed to reduce pain and swelling.
Follow instructions from your child’s physical therapist if physical therapy is part of your child’s treatment plan.
Have recommended checkups including seeing an orthopedic (bone) surgeon if your care team recommends it.
Questions to ask your care team
What is my child’s risk for avascular necrosis?
How can we manage pain and other symptoms?
What follow up care does my child need?
Is my child's avascular necrosis going to get worse, stay the same, or get better?
What activities should my child avoid?
Key points about avascular necrosis
Avascular necrosis (osteonecrosis) occurs when areas of bone die because of poor blood supply.
Children with some cancers or blood disorders or who undergo certain treatments are at risk for developing avascular necrosis.
Your care team can help you develop a plan to manage AVN. This may include physical therapy, medicines, rest, and other approaches.
Some patients may need surgery to improve blood flow and relieve pressure within the bone.
If joint damage is severe, your child may eventually need a joint replacement.
Some childhood cancer treatments can cause a loss of bone strength. This loss is especially concerning because bones normally grow and become heavier during childhood and adolescence.
