Osteonecrosis, also known as avascular necrosis, occurs when the normal supply of blood flow to a bone is reduced or cut off, causing that part of the bone to die. Traumatic injuries to the hipbone, such as fractures or joint dislocations, are common causes of osteonecrosis.

In some cases, other medical conditions like sickle cell anemia or Gaucher’s disease can cause avascular necrosis. These diseases make it hard for blood to move through the bone because they increase the amount of pressure inside the bone. HIV, lupus, and diabetes also increase a person’s chances of developing osteonecrosis.

People who take high doses of corticosteroids for long periods of time are at a higher risk for developing osteonecrosis. Cancer treatments (particularly radiation), organ transplants, and dialysis also can contribute to osteonecrosis developing. Heavy, long-term alcohol use can also cause this painful condition.

Symptoms of Osteonecrosis

Osteonecrosis may happen in any joint, but the two joints most prone to developing osteonecrosis are the hip and knee.

In the hip, pain is typically the first symptom.  This may lead to a dull ache or throbbing pain in the groin or buttock area.

In the knee, pain on the inside of the knee is typically the first symptom.  This pain may occur suddenly and be triggered by a specific activity or minor injury.

In many cases, avascular necrosis is not detected until the disease is quite advanced because there may be no discernible symptoms in the early stages of the condition. As it worsens, there may be pain in the joint during weight-bearing activities. Eventually, pain will occur during movement and sometimes even when at rest.

Treatment for Osteonecrosis

Treatment options for avascular necrosis depend on:

• The stage of your disease
• The amount of bone affected
• Which bone is affected
• The underlying cause of the disease

If caught in its early stages, osteonecrosis may be treated without surgery.

Nonsurgical Treatment for Osteonecrosis of the Hip

While being treated for avascular necrosis, it may be necessary for you to use crutches for several months to avoid further damage. Physical therapy exercises may also help maintain the range of motion in the hip joint.

• Over-the-counter anti-inflammatory drugs may help to relieve the pain; be sure to talk with your physician before taking any new medications.
• Drugs that are commonly used to treat osteoporosis may help to slow the progression of osteonecrosis.
• Cholesterol drugs can help keep the blood vessels that flow into the bones from becoming blocked.
• Restricting physical activity and limiting the amount of weight placed on the hip joint can help slow the development of further damage to the hip bones.
• Electrical stimulation, where electrical currents stimulate the body through electrodes attached through the skin, encouraging bone growth to replace damaged bone.

Nonsurgical Treatment for Osteonecrosis of the Knee

If osteonecrosis is in the knee and the affected area is small, nonsurgical treatment may be all that’s needed.

• Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen can help reduce pain and swelling in the knee.
• Reduced weight bearing.  Your doctor may recommend using crutches temporarily to relieve pressure on the joint and allowing it to heal.
• Exercise.  A prescribed program of physical therapy can help strengthen your thigh muscles and maintain range of motion.  Water exercise may be recommended to further reduce stress on your knee joint.
• Activity modification.  Your doctor may recommend avoiding activities that aggravate symptoms.

Surgical Treatment

Surgery is a common treatment for osteonecrosis because in many cases the condition is far advanced by the time it has been detected. Surgeons may remove or reshape part of the damaged bone, or graft a healthy section of bone from another part of the body.

For osteonecrosis of the hip, if the disease is caught early, core decompression and grafting are sometimes successful in preventing collapse of the femoral head and development of arthritis.

Core decompression is a procedure wherein one or more holes are drilled into the femoral head to relieve pressure in the bone and create channels for new blood vessels to nourish the affected areas.  Core decompression is often combined with bone and cartilage grafting (osteochondral grafting) to help regenerate healthy tissue.

• An allograft is healthy bone tissue from a donor
• An autograft is healthy tissue taken from another bone in your body
• Synthetic bone grafts are also available.  Sometimes your own bone marrow cells may be mixed together with the graft substitute to help the bone regeneration process.
• A vascularized fibula graft is a small segment of bone taken from your fibula (the smaller bone in your leg), along with its blood supply (an artery and a vein).  This graft is transplanted into a hole created in the femoral neck and head.  The artery and vein are then reattached to help heal the area of necrosis.

For osteonecrosis of the knee, if a large portion of the bone surface is affected, or your pain does not respond to nonsurgical treatment, your doctor may recommend surgery.

• Arthroscopic debridement and microfracture.  Your doctor uses a tiny camera and miniature surgical instruments to remove loose bits of bone and damaged cartilage from inside the joint.  Your doctor may also drill multiple tiny holes, or microfractures, in the bone underlying a small lesion to encourage blood flow and a healing response.
• Core decompression and osteochondral grafting may also used to treat osteonecrosis of the knee.
• Autologous chondrocyte implantation (ACI).  Your own cartilage-producing cells are collected and cultured (multiplied) in a lab  for up to 6 weeks.  These cells are then implanted into the area of your knee with cartilage loss.  The cells then grow in the joing, replacing the damaged cartilage with healthy cartilage.
• Osteotomy may be performed on either the tibia (shin bone) or femur (thigh bone).  Your surgeon may cut and reshape damaged bone , or insert a wedge of  bone graft or synthetic bone to shift weight off the damaged area of your knee and relieving pressure and pain, and improving function.

Joint replacement surgery may be necessary if the hip or knee bone has already collapsed.