Magnetic resonance imaging (MRI) and computed tomography (CT) are usef
ul techniques for the objective documentation of the relation between
the femoral head and the acetabulum after closed or open reduction of
a developmental dislocation of the hip joint. Before the ossification
nucleus of the femoral head is sufficiently developed, MRI is preferre
d. For the evaluation of reduction from the 2nd year on, MRI and CT ar
e equivalent. However, in older children MRI may also be indicated for
the evaluation of cartilaginous structures or the diagnosis of femora
l head necrosis. CT in older patients may also be useful for 30 analys
is of bony structures, e.g. for planning complex osteotomies.