What is the diagnosis and treatment for Avascular Necrosis (AVN)?

From the Guidelines

Vascular necrosis, also known as avascular necrosis or osteonecrosis, is a condition that requires prompt diagnosis and treatment to prevent long-term sequelae, such as subchondral fracture and secondary osteoarthritis, and the most effective approach is early surgical prevention to prevent articular collapse and the need for joint replacements 1.

Definition and Pathophysiology

Vascular necrosis is defined as bone death due to inadequate vascular supply, with three possible mechanisms: vascular interruption, vascular occlusion, or extravascular intraosseous compression, most likely caused by lipid hypertrophy 1. It is a common condition that affects adults in their third to fifth decades of life, with an incidence of 10,000 to 20,000 new symptomatic cases per year in the United States 1.

Risk Factors and Clinical Presentation

Risk factors for vascular necrosis include trauma, corticosteroid therapy, alcohol use, HIV, lymphoma/leukemia, blood dyscrasias, chemotherapy, radiation therapy, Gaucher disease, and Caisson disease 1. The condition can lead to severe pain, even at rest, and may eventually cause joint collapse. Common sites affected include the femoral head, humeral head, tibial metadiaphysis, femoral metadiaphysis, scaphoid, lunate, and talus 1.

Diagnosis and Treatment

Early diagnosis of vascular necrosis is crucial to exclude other causes of pain and to allow for possible early surgical prevention 1. Imaging tests, such as X-rays, MRI, or bone scans, are essential for diagnosis and preoperative planning. Treatment depends on the stage of the disease and may include medication for pain management, physical therapy to maintain joint mobility, and reduced weight bearing with crutches. For advanced cases, surgical interventions, such as core decompression, bone grafting, joint replacement, or osteotomy, may be necessary 1.

Key Considerations

• The necrotic volume of epiphyseal osteonecrosis is predictive of future articular collapse, with femoral heads with necrotic volume >30% progressing to collapse in 46% to 83% of cases 1.
• The increased risk for femoral head collapse is associated with increased joint effusion, increased bone marrow edema, patient age >40 years, and increased body mass index (24 kg/m) 1.
• Noninvasive therapies, such as statins, bisphosphonates, anticoagulants, extracorporeal shock wave therapy, and hyperbaric oxygen, have limited supporting data 1.
• Invasive therapies, such as core decompression, aim to prevent articular collapse and delay or prevent the need for joint replacement 1.

From the Research

Vascular Necrosis Treatment

• The use of bisphosphonates in the treatment of avascular necrosis has been studied, with some studies showing favorable results in diminishing pain, improving mobility, and lowering the incidence of articular collapse 2.
• A systematic review of the use of bisphosphonates in the treatment of avascular necrosis found that there are no controlled and double-blind studies about the efficacy of bisphosphonates in the treatment of avascular necrosis, but noncontrolled studies appear to demonstrate favorable results 2.
• A study on the use of bisphosphonate combination therapy for non-femoral avascular necrosis found that a combination of oral alendronate and intravenous zolendronic acid provides a pragmatic solution to this rare entity, with pain relief and reduction in analgesic requirement seen in most patients 3.
• The management of vascular injuries, including those that can lead to vascular necrosis, requires early recognition of the injury, hemorrhage control, and urgent surgical consultation 4.

Bisphosphonate Therapy

• Bisphosphonates have been shown to prevent disease progression, bone collapse, and the requirement for surgery in avascular necrosis of the femoral head 3.
• A combination of oral alendronate and intravenous zolendronic acid has been found to be effective in the treatment of non-femoral avascular necrosis, with complete resolution of bone marrow edema seen in most patients 3.
• The use of bisphosphonates in the treatment of avascular necrosis is still not universally accepted, and more studies are needed to justify its use for this indication 2.

Vascular Injuries

• Vascular injuries represent a significant burden of mortality and disability, and require early recognition and management to prevent complications such as vascular necrosis 4.
• The management of vascular injuries includes hemorrhage control, damage control resuscitation, and urgent surgical consultation 4.