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Condition/Disorder Synonym

  • Avascular necrosis (AVN)

  • Osteonecrosis

  • Bone infarction

  • Ischemic bone necrosis

ICD-9-CM Codes

  • 733.4 Aseptic necrosis of bone

  • 733.42 Aseptic necrosis of femoral head and neck

ICD-10-CM Codes

  • M87 Osteonecrosis

  • M87.1 Osteonecrosis due to drugs

  • M87.2 Osteonecrosis due to previous trauma

  • M87.3 Other secondary osteonecrosis

  • M87.8 Other osteonecrosis

  • M87.9 Osteonecrosis, unspecified

Preferred Practice Patterns

Key Features


  • Avascular necrosis (AVN) is the result of disruption or loss of blood flow to a joint or bone resulting in tissue damage or death to the bone.

  • The femoral head is the most vulnerable site for the development of AVN.

    • - Particularly the anterolateral aspect, which is the principal weight-bearing region and site of greatest mechanical stress

Essentials of Diagnosis

  • Known causes of AVN can be traumatic or atraumatic and include corticosteroid use, alcohol abuse, or intravascular coagulation from marrow fat enlargement, vessel wall injury, or thromboembolic event.

  • Early imaging with magnetic resonance imaging (MRI) is imperative as successful conservative treatment correlates to earlier-stage AVN.

General Considerations

  • AVN of the hip in children is known as Legg-Calve-Perthes syndrome.

  • Can be idiopathic.

  • Clinical AVN affects the ends of long bones.

  • Theorized to result from local edema (compartment syndrome), occlusive vessel disease, fat embolism, or hypertrophy of fat cells which then block the supply of blood and result in necrosis and death of the marrow cells and osteocytes.

  • In femoral head AVN, the weakened and necrotic bony trabeculae fail under compressive loading that result in subchondral and ultimately articular collapse.


  • There are an estimated 15,000 to 20,000 new cases of femoral head AVN diagnosed each year in the United States.

  • Femoral head AVN accounts for 20% of the joint replacements in the United States yearly.

  • Femoral head AVN is most common in young males with an 8:1 male to female ratio.

  • Femoral head AVN has an age of onset is typically between 30 and 50.

  • Can occur in children: Legg-Calve-Perthes syndrome.

Clinical Findings

Sign and Symptoms

  • Early in the disease process patients are asymptomatic and diagnosis may be the result of incidental findings from imaging.

  • Femoral head AVN is characterized by pain or stiffness that develops in the hip region, and low-back pain or radiating pain to the knee.

  • Antalgic gait.

  • Pain in the groin.

  • Throbbing deep hip pain.

  • The rate of progression is variable.

  • Restricted hip internal rotation, flexion, and abduction.

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