Computed tomography in congenital hip dislocation. The role of acetabular anteversion.

Computed tomography usually can provide accurate documentation of the adequacy of a reduction in congenital dislocation of the hip. It should supplement other radiographic examinations when the status of a reduction is in question because the patient is wearing a plaster cast. The computed tomography scan provides a clear image of the reduction in the transverse plane, so that anterior or posterior subluxation of the femoral head can be easily detected. In addition it allows direct measurement of acetabular anteversion which previously had not been possible with non-invasive studies in the living patient. Radiation exposure is less than that for conventional tomography. We used computed tomography in five patients with congenital dislocation of the hip and our study provided new evidence concerning the role of acetabular anteversion in this condition. Acetabular anteversion was increased on the dislocated side in each patient, and returned to normal as treatment progressed.