Arthrography was used to study the development of the hip joint in fourteen fetuses ranging in age from fourteen weeks to term. The articular structures identified on the arthrogram of the newborn infant are present in the hip of the fourteen-week-old fetus and throughout development without any marked change in their relative size.
No extraordinary change in the depth or shape of the acetabulum was found. The bony roof was found to consist of central endchondral bone and lateral and medial sheets of perichondral bone. Development of the medial sheet precedes that of the lateral. The importance of this precedence is stressed and it is suggested that pressure of a displaced femoral head upon the lateral sheet of perichondral bone may lead to retardation of ossification in the lateral part of the bony roof.