[Pathogeny and natural history of congenital dislocation of the hip]

Based on a review of the literature, the authors have made a critical study of several etiological factors. Endogenous factors such as acetabular dysplasia, increased anteversion of the femoral neck, capsular laxity support the genetic theory but they are neither constant nor necessary and are only facilitating factors. The major factor seems to be a mechanical one linked to the position in uterus: hyperflexion with adduction and external rotation causing an abnormal pressure on the greater trochanter leading to an expulsion of the head upward and backward. This theory can explain the natural history of C D H which is first, at birth a hip unstability followed by to possible evolutions: either a persistent luxation becoming irreducible or a spontaneous stabilisation leading sometimes to complete healing or to residual abnormalities (subluxation or dysplasia). This concept suggests practical conclusions: the importance of an early diagnosis, the selection of the signs of the hip at risk the pattern of prevention, the importance of non clinical investigations, the principles of the treatment based on postures, the indications for the different types of treatment.