Avascular necrosis

Background

• Also called osteonecrosis, ischemic necrosis, bone infarction
• Interruption in vascular supply leads to death of osteocytes and marrow, necrosis, and (eventually) collapse of dead segment

Causes/Risk factors

Nontraumatic

• Sickle cell disease
• Exogenous corticosteroids, Cushing's disease
• Collagen vascular disease (e.g. SLE)
• Chronic kidney disease (renal osteodystrophy), post-renal transplant
• Pancreatitis
• Radiation therapy
• HIV
• Caisson Disease (aka dysbarism)
• Legg-Calve-Perthes disease
• Slipped capital femoral epiphysis (may be atraumatic or minor trauma)
• Idiopathic

Traumatic

• Hip dislocation
  • High risk if not reduced within 6h
• Femoral neck fracture
• Major talus fracture (talar head/neck)
• Navicular fracture (central part of bone is avascular)
• Proximal humerus fracture
  • Risk factors: 4 part fractures, head split, short calcar segments, disrupted medial hinge
• Elbow fractures (trochlear, lateral/medial epicondylar)
• Lunate fracture, Capitate fracture

Clinical Features

• Depends on cause and location

Differential Diagnosis

• Depends on cause and location

Evaluation

• Plain films generally first step
• Further evaluation depends on cause/location

Management

• Ortho consult
• Usually splint, non-weightbearing

See Also

• Avascular necrosis of hip