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  • Bone infarction
  • Ischemic bone necrosis
  • Osteonecrosis

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  • 733.4 Aseptic necrosis of bone
  • 733.42 Aseptic necrosis of femoral head and neck

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  • 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

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Description

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  • AVN results from disrupted or lost blood flow to a joint or bone, resulting in damage to or death of bone tissue
  • Femoral head is the most vulnerable site for development of AVN
    • Anterolateral aspect is particularly vulnerable as it is the principal weight-bearing region and site of greatest mechanical stress

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Essentials of Diagnosis

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  • Known causes can be traumatic or atraumatic, including:
    • Corticosteroid use
    • Alcohol abuse
    • Intravascular coagulation from marrow fat enlargement, vessel wall injury, or thromboembolic event
  • Early imaging with MRI is imperative as success of conservative treatment correlates with earlier stages

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General Considerations

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  • AVN of the hip in children known as Legg-Calvé-Perthes syndrome
  • Can be idiopathic
  • Clinical AVN affects the ends of long bones
  • May result from local edema (compartment syndrome), occlusive vessel disease, fat embolism, or hypertrophy of fat cells, which block blood supplies, result in necrosis/death of marrow cells and osteocytes
  • In femoral head AVN, weakened and necrotic bony trabeculae fail under compressive loading, results in subchondral and articular collapse

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Demographics

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  • Estimated 15,000 to 20,000 new cases of femoral head AVN each year in the United States
  • Accounts for 20% of joint replacements in the U.S. annually
  • Most common in young males; male-female ratio 8:1
  • Typical age of onset between 30 and 50 years
  • Can occur in children (Legg-Calvé-Perthes syndrome)

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Sign and Symptoms

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  • Patients are asymptomatic early in disease process; diagnosis may result from incidental findings on imaging test
  • Characterized by pain, stiffness in hip region, low-back pain, or radiating pain to knee
  • Antalgic gait
  • Pain in groin
  • Throbbing deep-hip pain
  • Rate of progression is variable
  • Restricted hip internal rotation, flexion, abduction

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Functional Implications

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  • Patients must avoid impact activities to preserve joint integrity
  • Limited mobility
  • Limited/restricted household and work-related activity
  • Decreased overall activity and participation
  • Loss of normal joint ROM results in compensatory movement patterns with potential for injury in other regions
  • Restricted weight-bearing may be prescribed during periods of symptom exacerbation
  • Joint replacement often necessary, carries post-surgical ROM and weight-bearing restrictions

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  • Strong association of nontraumatic AVN with corticosteroid use and alcoholism
    • Both believed to affect breakdown of fatty substances and disrupt blood flow
  • Trauma
  • Intravascular coagulation from marrow fat enlargement
  • Vessel wall injury
  • Thromboembolic event
  • Cushing’s syndrome
  • Gaucher's disease
  • Systemic ...

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