MyPACS.net: Radiology Teaching Files > Case 3173677

previously visited AVASCULAR NECROSIS OF THE FEMORAL HEAD
Contributed by: Fritsch & Thompson.
Patient: 47 year old male
History: 47 yr. old man with chronic left hip pain.
Images:[small]larger

Fig. 1: AP bilateral hips

Fig. 2: Frogleg Left hip

Fig. 3: Coronal T1

Fig. 4: Ccoronal PD fatsat

Fig. 5: Axial T1

Fig. 6: Axial PD fatsat

Fig. 7: Vascular supply of the femoral head.

Fig. 8: AVN pathology

Fig. 9: Causes of AVN
Findings:

Plain films show mottled increased radiopacity of either femoral head, more prominent on the left, and a slightly "out of round" appearance of the left femoral articular cortex. There is a subtle subchondral radiolucent "crescent sign" paralleling the articular cortex of the left femoral head and a focal area of collapse along the superolateral articular margin.

MR PD fatsat images show the serpiginous high signal border surrounding involved areas of both femoral head but more advanced in the left hip joint (sympotmatic side).  Also note effusion in left hip joint.  The right hip joint was asymptomatic and the changes are consistent with late Stage 1 to Stage 2 (Ficat & Arlet).  The left joint shows more advance changes with early collapse of the femoral head (Stage 4).

Diagnosis: Bilateral avascular necrosis of the femoral heads
Discussion:

Disrupted blood supply to all or part of the femoral head is the mechanism of insult. Avascular necrosis typically presents in the 20-50 age range as chronic hip pain, although pain may radiate to the lower thigh/knee area. Many cases are apparently spontaneous, although recognized predisposing factors include:

trauma (AVN may complicate 10% of non-displaced and up to 30% of displaced femoral neck fxs),
corticosteroid use (accounting for 5-25% atraumatic cases)
alcoholism
Sickle cell anemia and other coagulopathies
idiopahtic
Barotrauma

Imaging findings are classified as stages 1-4 (Ficat and Arlet). Plain film X-ray findings are not sensitive to early disease and are normal in the 1-2 stages. Plain films are typically not positive until stage 3,when loss of the spherical shape of the femoral head occurs. MR evaluation is the method of choice and can detect stage 1 disease. A "double line sign" of serpiginous high signal along the periphery of the affected area outlined by an outer hypointense line is usually best seen on T2 images, but can be seen on the PDfatsat.



References:

DIAGNOSTIC IMAGING ed.1 Stoller, Triman, Bredella, et.al. Amirsys pub. 2004

Case Of the Week: 11/9/2005

MRI Case of the Week: 8/23/06

Comments:
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Additional Details:

Case Number: 3173677Last Updated: 08-16-2006
Anatomy: Skeletal System   Pathology: Vascular
Modality: Conventional Radiograph, MR, OtherAccess Level: Readable by all users
Keywords: avascular necrosis; aseptic necrosis; ischemic necrosis; osteonecrosis

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