On congenital dislocation of the hip.

Studies of congenital dislocation of the hip have ranged in their conclusions from the words of Hey Groves (1928) : “ Congenital dislocation of the hips is a deformity which is mysterious in its origin, insidious in its course and relentless in its final crippling results,’ ‘ to those of Brewster (1945) : “ The etiology of the congenital dislocated hip is unknown. Many theories have been advanced, any one is just as good as another.’ ‘ Browne (1948) brought some order and simplicity out of chaos when he stated: “ The hip is displaced during intra-uterine life by a thrust upon the knee by the uterine wall, which sends the head of the femur backwards out of the acetabulum. ‘ ‘ He made a valuable contribution in implying that the process was an accident, and in emphasising the necessity of movement in treatment, but one feels that, when tile movements of the gravid uterus are considered, his conception of the etiology is unlikely. fhe body of the uterus is maintained in a state of tone as the foetus grows, but intermittent slow contractions of the whole uterus occur throughout pregnancy. Localised parts of the uterus can, of course, contract as a result of cold hands, brusque handling, or the active movements of the child, but this also is a slow hardening of the muscle rather than an active ‘ ‘ thrust. ‘ ‘ It is hardly possible that either of these movements could give an active thrust to the foetal knee and dislocate the hip. Even if a part of the uterus were capable of taking a solid thrust at the foetal knee it would instantly be opposed by an equal and opposite force at the hip in accordance with Pascal’s principle, which force would prevent dislocation. The frequency of bilateral dislocation is a further point against this hypothesis. Finally, a number of cases have been described in the literature in which congenitally dislocated hips were found in extra-uterine pregnancies. ‘ ‘ Heusner records a bilateral dislocation in a five months’ foetus from an extra-uterine pregnancy, and a unilateral one in a foetus, ten inches long.” (Tubby 1912.) The case reported by Lesk (1948) as “ Extrauterine Full Term Pregnancy ‘ ‘ was delivered by laparotorny in March 1947. I was privileged to see the child at the Children’s Hospital, Vancouver, in November 1948 when she was twenty months old. She had a congenital dislocation of the left hip. As recorded by Tubby (1912), some writers have “ gone so far as to say that in some cases the head had not occupied the acetabulum at all, and therefore dislocation is a misnomer. More recent investigations into the manner of development of the hip bone do not confirm this idea. The mesoblast, from which the cartilaginous models of the bones are developed, forms at first an unbroken mass in this region. The researches of Petersen (1893) and von Friedlaunder (1892) show that the shape of the articular surfaces is defined before the joint cleft is differentiated, and before rotation of the limb takes place.”