Congenital dislocation of the hip in identical twins.

As early as 1678 Pare stated that lame people beget lame children, and in 1882 KrUnlein compiled the family trees of many generations of children with congenital dislocation of the hip. In series of patients with congenital hip dislocation a hereditary factor was noted in 20 2 per cent by Isigkeit (1928), in 227 per cent by Scaglietti (1932) and in 6l per cent by Francillon (1937). Mercer (1950) stressed the importance of the hereditary influence. A different emphasis is given by those who believe that the essential cause of the dislocation is intra-uterine pressure from oligohydramnios with unusual transverse lie, breech presentation and prolonged abnormality of position of the femoral head in relation to the pelvis during intra-uterine life. The particular relation of this to anteversion of the upper end ofthe femur was discussed by Krida (1928), Le Damany (1908), Badgley (1943) and Somerville (l953b). Lorenz and Reiner (1905) ascribed an important role in the etiology to hereditary influences, but at the same time tried to develop a mechanical theory. It was expected that a study of twin children might yield a decisive contribution, and this was in fact possible in the remarkable series reported by Idelberger (1951), who himself examined 138 living identical twins with congenital dislocation of the hip. Before discussing his conclusions we report an example of congenital dislocation of the hip in Italian twin sisters who came north to Switzerland with the influx of italian workers.