Insufficiency fracture of the acetabulum without apparent trauma.

A 76-year-old woman presented history of left hip joint pain on walking, which occurred after she bent to move a planter. Plain radiographs showed no fracture. Bone scintigraphy revealed accumulation, and magnetic resonance imaging showed a low signal area on T1-weighted images. We diagnosed an insufficiency fracture and pain decreased naturally on conservative treatment. Insufficiency fracture of the acetabulum should be considered when elderly patients have hip joint pain. Magnetic resonance imaging and bone scintigraphy is most useful for the diagnosis.