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Avascular Necrosis of the Femoral Head
Aka: Avascular Necrosis of the Femoral Head, Hip Avascular Necrosis, Hip Osteonecrosis, Hip AVN
- See Also
- Hip Pain
- Hip Pain Causes
- Leg-Calve-Perthes Disease
- Epidemiology
- Incidence: 20,000/year in United States
- Most common in men ages 30-50 years old
- Leg-Calve-Perthes Disease is idiopathic osteonecrosis of the femoral head in children ages 2-12 years old
- Risk Factors (compromise femoral head blood supply further)
- Most significant common cases denoted (*)
- Pregnancy
- Chemoradiation
- Sickle Cell Anemia
- Hematologic Causes
- Coagulopathy
- Sickle Cell Disease (*)
- Gastrointestinal Causes
- Chronic Liver Disease
- Chronic Pancreatitis
- Rheumatologic Causes
- Gout
- Systemic Lupus Erythematosus
- Medication, substances and exposures
- Chemotherapy (*)
- Radiation Therapy (*)
- Alcohol Abuse
- Corticosteroids
- Lipid Disorders
- Hyperlipidemia
- Gaucher Disease
- Miscellaneous Causes
- Diabetes Mellitus
- Pregnancy (*)
- Pathophysiology
- Femoral head subchondral bone with irreversible anoxia
- Results in secondary osteocyte death
- Osteoblasts are active in surrounding bone
- Subchondral trabeculae fails and result in collapse of Hip Joint space
- Symptoms
- Progressive Groin Pain or Hip Pain, gradually increasing over weeks to months
- Starts unilaterally (but ultimately bilateral in over 70% of cases)
- Radiation into medial thigh
- Provoked with weight bearing (especially while standing with all weight on affected leg)
- Pain at rest suggests advanced avascular necrosis
- Signs
- Hip Range of Motion
- Normal initially
- Later significantly limited active and passive range of motion due to joint destruction and collapse
- Differential Diagnosis
- See Hip Pain
- Diagnosis
- Typically delayed diagnosis until advanced stages (due to insidious, gradual presentation)
- Imaging
- MRI Hip (preferred)
- XRay Hip (first-line, initial study)
- Stage 0 and 1: Normal XRay
- Stage 2: Hip sclerosis, bone cysts and Osteopenia
- Stage 3: Crescent sign
- Femoral head flattening of the superior aspect
- Subchondral Fracture parallel to articular surface
- Stage 4: Femoral head collapse
- Stage 5-6: Joint destruction
- Management
- Orthopedic referral
- Non-Sickle Cell patients
- Hip replacement in nearly all cases
- Sickle-Cell patients
- Conservative management with focus on pain relief and mobility, physiotherapy
- Surgery is rarely indicated in Femoral Head AVN in Sickle Cell Anemia
- Prognosis
- Responsible for 12% of all hip replacements in the United States
- References
- Shahideh (2013) Crit Dec Emerg Med 27(9):10-18
- Welsh and Welsh (2016) Crit Dec Emerg Med 30(11): 15-23