Early MRI findings of the acetabulum and femoral head in a dysplastic hip resulting in a rapid destruction of the hip joint.

We documented a case of rapidly destructive arthrosis of the hip joint (RDA), in whom abnormal findings were observed not only in the femoral head but also in the acetabulum on magnetic resonance images (MRI) in the early stage. Radiographs made 1 month after the onset of pain showed a slight narrowing of the joint space. MRI obtained 2 months after the onset detected small foci of low signal intensity in the subchondral area of the femoral head on the T1-weighted images, and a linear pattern of high signal intensity in the lateral side of the acetabulum on the T2-weighted images. During the 17-month follow-up period, this case eventually underwent massive destruction of the femoral head as well as the acetabulum.