Radiology Resident Case of the Week

Osteonecrosis - Bilateral femoral heads

August 1, 1996

Clinical Sx:
left hip pain
this seventeen year old female presents with a history of acute lymphocytic leukemia, with records of the illness going back to 1990.

Etiology/Pathophysiology
in this case the process is most likely related to steroid use. the causes associated with the process include: toxins-

1. steroids
2. anti-inflammatory drugs
3. alcohol
4. immunosuppressives

1. idiopathic
2. fractures
3. radiotherapy
4. heat
5. fat embolism

inflammatory-

1. rheumatoid artheritis
2. systemic lupus erythematosus
3. scleroderma
4. infection
5. pancreatitis

metabolic and endocrine-

1. pregnancy
2. diabetes
3. cushing's syndrome
4. hyperlipidaemias
5. gout

Hematopoetic disorder

1. hemoglobinopathies
2. polycythemia rubra vera
3. Gaucher's disease
4. hemophilia

thrombotic and embolic-

1. Dysbaric osteonecrosis
2. Arteritis According to Dahnert, involvement of one hip increases the risk to the contralateral hip to up to 70%

Pathology:

Miscellaneous

Imaging

plain film:
grade 0= normal/ mild degenerative change grade 1= barely detectable trabecular mattling
grade 2= faocal sclerosis/ trabecular rarefaction in femoral head
grade 3= mild alteration in femoral head contour + normal joint space
grade 4 = profound flattening of femoral head
grade 5= narrowing of joint space and acetabular involvement

Nuc Med= early- cold, photopenic defect( interrupted blood flow) late- increased uptake( capillary infiltrate and new bone synthesis)

MRI-
1) central area of high signal intensity on T1WI
2) large irregular areas of decreased signal intensity extending into femoral neck
3) low intensity band/ring on T1WI
4) cleft of low signal intensity on T1WI and high signal intensity on T2WI.

DDX

Key references
DAhnert, Radiology Review Manual Chapman, Radiological differential diagnosis

ACR Code

Keywords:
AVN, Osteonecrosis

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Last Modified: April 24, 1997