Avascular Necrosis (AVN)

Question 1

Causes and risk factors for AVN

Answer 1

• Alcohol. Several drinks a day can cause fat deposits to form in your blood, which lower the blood supply to your bones.
• Bisphosphonates. These medications that boost bone density could lead to osteonecrosis of the jaw. This could be more likely if you’re taking them for multiple myeloma or metastatic breast cancer.
• Medical treatments. Radiation therapy for cancer can weaken bones. Other conditions linked to AVN include organ transplants, like kidney transplants.
• Steroid drugs. Long-term use of these inflammation-fighting drugs, either by mouth or in a vein, leads to 35% of all cases of nontraumatic AVN. Doctors don’t know why, but longtime use of medications like prednisone can lead to AVN. They think the meds can raise fat levels in your blood, which lowers blood flow.
• Trauma. Breaking or dislocating a hip can damage nearby blood vessels and cut the blood supply to your bones. AVN may affect 20% or more of people who dislocate a hip.
• Blood clots , inflammation , and damage to your arteries . All of these can block blood flow to your bones

Question 2

Common sites of development of AVN

Answer 2

• Commonly ffects ends of long bones such as the femur
• Can also affect the humerus, knees, shoulders, ankles and jaw

Question 3

Diagnosis and treatment of AVN

Answer 3

• Diagnosis
  
  • MRI/CT
  • X-rays (although changes usually late sign)
  • Bone scan using contrast to highlight injured and healing bone
• Management
  
  • Medical - Blood thinners, NSAIDs, cholesterol lowering drugs
  • Surgical - Bone grafts, osteotomy, joint replacement, core decompression and electrial stimulation