Hip CT in congenital dislocation: appearance of tight iliopsoas tendon and pulvinar hypertrophy.

The iliopsoas tendon can interpose between the femoral head and the acetabulum, preventing reduction or stability of reduction of a dislocated hip by a closed method. The tendon produces an infolding of the capsule and labrum. This infolding of the capsule and labrum creates an "isthmus" between the capital and the acetabular parts of the capsule. This deformity of the capsule was recognizable on computed tomography (CT) in 10 patients, all of whom had surgical confirmation of the findings. The presence of hypertrophied pulvinar can also be recognized by CT.