Avascular necrosis, femoral head

• Bone infarction
• Ischemic bone necrosis
• Osteonecrosis

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

• 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

• 4H: Impaired Joint Mobility, Motor Function, Muscle Performance, and Range of Motion Associated With Joint Arthroplasty
• 4I: Impaired Joint Mobility, Motor Function, Muscle Performance, and Range of Motion Associated With Bony or Soft Tissue Surgery

Description

• 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

Essentials of Diagnosis

• 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

General Considerations

• 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

Demographics

• 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)

Sign and Symptoms

• 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

Functional Implications

• 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

• 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 ...