Avascular (Aseptic) Necrosis of the Femoral Head (Hip) The 5 Minute
Pediatric Consult
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Avascular (Aseptic) Necrosis of the Femoral Head
(Hip) |
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John P. Dormans
DEFINITION
Avascular (aseptic) necrosis (AVN) results from the
interruption of the blood supply of bone (either traumatic or nontraumatic
occlusion). The femoral head is the most common site of AVN.
CAUSES
- Traumatic
- After fracture
- After hip dislocation
- After slipped capitol femoral epiphysis
- After casting, bracing, surgery
- Nontraumatic
- Idiopathic (older, after physeal closure); similar to adult AVN
- Idiopathic (younger, before physeal closure); see Perthes
- Caisson disease
- With sickle cell disease
- After septic arthritis
- With steroids or chemotherapy
PATHOPHYSIOLOGY
- Death and necrosis of bone with gradual return of blood supply
- Necrotic bone gradually resorbed and replaced by new bone
EPIDEMIOLOGY
- Variable, depending on cause
GENETICS
- Variable, depending on cause
COMPLICATIONS
- Decreased range of motion
- Osteoarthritis
- Physeal arrest with growth disturbance
PROGNOSIS
- Variable, depending on cause
- Trauma
- Osteochondral fracture
- Impaction fracture
- Epiphyseal/physeal fracture
- Infection
- Osteomyelitis
- Septic arthritis
- Neoplastic process
- Epiphyseal tumors (chondroblastoma, Trevoir disease, et al.)
- Rheumatologic processes
HISTORY
- Onset (gradual or after traumatic event)
- Association with:
- Trauma
- Medications (steroids or chemotherapy)
- Casting, splinting, surgery (iatrogenic)
- Pain, limping?
- Stiffness (decreased range of motion)
- Gait
- Limping
- Antalgic
- Trendelenburg gait
- Range of motion
- Flexion and extension
- Abduction and adduction
- Internal and external rotation
- Hip joint irritability (short arc rotation)
- Sign of other disease process (e.g., sickle cell disease)
- Physical examination trick
- Loss of internal rotation is usually the first and most affected loss of
motion seen.
TESTS
Laboratory examinations should be normal in most
forms of AVN of the femoral head.
Imaging
- Usual
- Sclerosis
- Subchondral fracture
- Collapse
- Reossification
- Repair
- Variable
- Cysts
- Physeal growth arrest (young)
- Early osteoarthritis
- Subluxation
DRUGS
- NSAIDs may be effective in decreasing associated inflammation.
- If associated with steroid use, discontinuation or elimination if possible
TREATMENT PRINCIPLES
- Maintain range of motion (physical therapy, traction, continuous passive
motion).
- Contain the femoral head in the acetabulum (see Perthes
principles).
- Surgery
- Redirectional osteotomy
- Femoral or acetabular (see containment operations of Perthes)
- Core decompression to introduce new blood supply
DURATION OF THERAPY
- Variable, depending on cause
DIET
- Thought not to alter disease process; recommend general balanced diet
WHEN TO EXPECT
IMPROVEMENT
- Variable, depending on cause
SIGNS TO WATCH FOR
- Subluxation
- Early osteoarthritis
- Growth arrest
PROGNOSIS
- Overall, good if mild involvement (usual) and patient is young
- See Prevention
below
PREVENTION
- Traumatic
- After fracture: early anatomic reduction and stable internal fixation is
key.
- After hip dislocation: early reduction is key.
- After slipped capitol femoral epiphysis: associated with unstable grade
3 slips.
- After casting, bracing, surgery: prevention is key.
- Nontraumatic
- Idiopathic (older, after physeal closure); similar to adult AVN
- Idiopathic (younger, before physeal closure): see Perthes
disease
- Caisson disease: rare now
- With sickle cell disease: good medical management key
- After septic arthritis: early surgical drainage of hip key to prevention
- With steroids or chemotherapy: do not use unless no other
alternatives.
| COMMON QUESTIONS
AND ANSWERS |
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Q: What type of medication is associated with
AVN of the hip?
A: Steroids
Q: For AVN in children, is younger or older
age associated with a better prognosis?
A: Younger age
ICD-9-CM
Legg perthe 732.1
Avascular
necrosis 733.40
Lahdes-Vasama T, Lamminen A, Merikanto J, Marttinen
E. The value of MRI in early Perthes’ disease: an MRI study with a 2-year
follow-up. Pediatr Radiol 1997;27(6):517–522.
Copyright
© 2000 Lippincott Williams & Wilkins
M. William
Schwartz, Louis M. Bell, Jr., Peter M. Bingham, Esther K. Chung, David F.
Friedman and Andrew E. Mulberg, The 5 Minute Pediatric Consult