Avascular Necrosis

Avascaular Necrosis (AVN) or osteonecrosis, is a condition that happens within bones that causes death to the bone cells. The cell death is most often caused by a lack of blood flow to the specific part of a bone. There are some bones that are more susceptible to this condition because of their limited blood supply. These bones included the femoral head but can happen in the knee, shoulder, hand and foot as well. The condition is most common in people between the ages of 30 and 50 but can occur in any age.

Causes

• Trauma: Breaking the femoral neck or dislocating the hip can can interrupt the blood flow to the femoral head causing AVN.
• Medications: Some medications such as high dose oral steroids, and high dose long term bisphosphonates (typically the jaw bone or mandible).
• High Risk Activities: Excessive alcohol intake, smoking and deep sea diving all have been associated with AVN.
• Other Medical Conditions: Hyperlipidemia, hypercoagulability, sickle cell disease, Gaucher’s disease, HIV/AIDS, systemic Lupus erythematosus, collagen vascular disease, pancreatitis, and idiopathic family history of AVN are all associated with AVN.
• Pregnancy can cause AVN but is more commonly associated with a similar condition called transient osteoporosis of the hip which typically resolves with non-surgical treatment.
• Idiopathic: Almost 25% of people have none of the above risk factors and therefore have an unknown cause.

Symptoms

In the early stages avascular necrosis often causes no symptoms. As the condition worsens and the bone weakens, the hip joint can cause pain with weightbearing in the groin or buttoc area. Eventually, you might feel the pain constantly even when you’re lying down.

Pain can be mild or severe and usually develops gradually. Pain associated with avascular necrosis of the hip might center on the groin, thigh or buttock. Some people develop avascular necrosis on both sides (bilaterally) — such as in both hips or in both knees.

When to see a doctor

See Dr. Faucett if you have persistent pain in any joint. Seek immediate medical attention if you believe you have a broken bone or a dislocated joint.

Complications

Untreated, avascular necrosis worsens with time. Sometimes it may stabilize. Eventually, the bone can collapse causing the bone to lose its smooth shape, leading to severe arthritis.

Prevention

To reduce your risk of avascular necrosis:

• Limit alcohol: Heavy drinking is one of the top risk factors for developing avascular necrosis.
• Keep cholesterol levels low: Tiny bits of fat are the most common substance blocking blood supply to the femoral head.
• Monitor steroid use: Make sure Dr. Faucett knows about your past or present use of high-dose steroids. Steroid-related bone damage appears to worsen with repeated courses of high-dose steroids.
• Avoid smoking: Smoking increases the risk of AVN
• Always monitor your dive ascents and avoid unsafe diving practices.

Diagnosis

• Physical exam: During a physical exam Dr. Faucett will press around your hip joints, checking for tenderness. Dr. Faucett might also move the joints through a variety of positions to see if your range of motion has been reduced.
• Imaging tests:
  • X-rays: They can reveal bone changes that occur in the later stages of avascular necrosis. In the condition’s early stages, X-rays usually appear normal.
  • MRI: A MRI provides detailed images that can show early changes in bone that might indicate avascular necrosis.
  • Bone scan: A small amount of radioactive material is injected into your vein. This tracer travels to the parts of your bones that are injured or healing and shows up as bright spots on the imaging plate.
  • CT Scan: A CT scan is a series of x-rays compiled to produce 2D and 3D images of the bones and tissues.

Treatment

The goal is to prevent further bone loss and restore the bone and hip function.

Medications

In the early stages of avascular necrosis, symptoms might be eased with medication and therapy. Dr. Faucett might recommend:

• Nonsteroidal anti-inflammatory drugs: Medications, such as ibuprofen (Advil, Motrin IB, others) or naproxen sodium (Aleve) might help relieve the pain associated with avascular necrosis.
• Osteoporosis drugs: Medications, such as alendronate (Fosamax, Binosto), might slow the progression of avascular necrosis, however they also can slow the repair phase. The evidence is mixed. Another medication called teriparatide (Forteo) has also been tried to help improve bone growth but this is off label.
• Cholesterol-lowering drugs: Reducing the amount of cholesterol and fat in your blood might help prevent the vessel blockages that can cause avascular necrosis.
• Blood thinners: If you have a clotting disorder, blood thinners, such as warfarin (Coumadin, Jantoven), might be recommended to prevent clots in the vessels feeding your bones.

Rest and Activity Modification

Reducing the weight and stress on your affected bone can slow the damage. You might need to restrict your physical activity or use crutches to keep weight off your joint for several months.

Physical Therapy

• A physical therapist can teach you exercises to help maintain or improve the range of motion in your joint.
• Electrical stimulation. Electrical currents might encourage your body to grow new bone to replace the damaged bone. Electrical stimulation can be used during surgery and applied directly to the damaged area. Or it can be administered through electrodes attached to your skin.

Surgical and other procedures

Because most people don’t develop symptoms until avascular necrosis is fairly advanced, Dr. Faucett might recommend surgery. The options include:

Core Decompression

Dr. Faucett removes part of the inner layer of your bone. Besides reducing your pain, the extra space within your bone stimulates the production of healthy bone tissue and new blood vessels.

Bone Transplant (Graft)

This procedure can help strengthen the area of bone affected by avascular necrosis. In some cases, the graft is a section of healthy bone taken from another part of your body. Most commonly Dr. Faucett uses a bone substitute to fill the void an encourage bone healing.

Bone Reshaping (Osteotomy)

A wedge of bone is removed above or below a weight-bearing joint, to help shift your weight off the damaged bone. Bone reshaping might enable you to postpone joint replacement.

Total Hip Replacement

If your diseased bone has collapsed or other treatments aren’t helping, you might need surgery to replace the damaged parts of your joint with plastic and ceramic parts.

Regenerative Medicine Treatment

Bone marrow aspirate concentration (BMAC) is a newer procedure that might be appropriate for early stage avascular necrosis of the hip. Stem cells are harvested from your bone marrow. This is often applied during one of the above surgeries.