Bilateral hip avascular necrosis

Case contributed by Paul Simkin
Diagnosis almost certain


Known stage I AVN of both hips due to steroid use. Acute onset pain after starting zalendronic yesterday. Fever, tachycardia and hypertensive. Unclear focus. Worsening AVN? Cause of hip pain?

Patient Data

Age: 25 years
Gender: Female

Moderate bilateral joint effusions have developed since the previous MRI. Crescentic T2 high signal is seen in both femoral heads, extending more than 50% of the articular surface. This was subtly present on the previous MRI, but is now much larger, and is keeping with a subchondral fracture. No collapse of the femoral head at this stage.

The marrow signal change within the femoral head/neck bilaterally, as well as the posterior acetabulum, is otherwise unchanged. No fracture through the femoral necks identified.


Chronic bilateral hip avascular necrosis with apparently extended subchondral fracture lines involving >50% of the femoral heads. Bilateral effusions have worsened.


Acetabulofemoral joint space is preserved.

There is minor flattening of theweight-bearing femoral articular surface (on the oblique projection) of the right hipand adjacent subchondral lucency.

Minor subchondral lucency is seen in the left femoral head (on the oblique projection), however the articular surface remains smooth.

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