Avascular Necrosis

Description

• Avascular necrosis (AVN) is death and eventual architectural collapse of bone as a result of ischemic injury or damage to bone or bone marrow elements. AVN most commonly affects the epiphysis of long bones; the hip (femoral head) is most susceptible but also can occur in the shoulder, knee, ankle, and wrist.
• Bone collapse at these joints can lead to cartilage breakdown and arthritis.

Epidemiology

Incidence

• About 20,000 to 30,000 new cases of AVN are reported each year.
• AVN usually affects people <50 years of age (1).
• Gender risk varies based on etiology.

Etiology and Pathophysiology

• Combination of metabolic, genetic, lifestyle, and environmental causes
• Traumatic (nonunion, Perthes disease, joint dislocation) accounts for most cases.
• Chronic glucocorticoid use and alcohol abuse account for >80% of nontraumatic (2).
• Bisphosphonates (AVN of the jaw) (1,2)
• Embolic (decompression disease, sickle cell)

Risk Factors

• Systemic lupus erythematosus (SLE) (3)
• HIV and antiretroviral therapy
• Radiation and chemotherapy

General Prevention

• Avoid or limit medications and substances that can cause AVN, such as steroids or alcohol.
• Monitor fractures for signs of nonunion.
• High index of suspicion in high-risk population (SLE, steroid use, alcohol abuse)
• Early surgical intervention prior to joint collapse