Radiological evaluation of asymmetrical limitation of hip abduction during the first year of life.

Asymmetrical limitation of abduction of the hip may be found on screening of children in the first year of life. The clinical features identified may occur in congenital dislocation of the hip but most infants do not have or develop hip dislocation. Radiological changes are present on the side of limitation of abduction and include a higher acetabular angle, retardation of femoral head epiphyseal development, pelvic obliquity and a rotational deformation of the pelvis in the transaxial plane. The appearances are postural deformities due to persistent infant positioning and are self-correcting. If aggressive treatment methods are to be avoided, the radiologist should not confuse these changes with those of congenital hip dislocation or subluxation.