Since ancient times there has been a sustained interest in the role of the pelvic joints during pregnancy and labor. Hippocrates, Avicenna, Pare, Vesalius, Mauriciau, Smellie and Baudelocque1 were fascinated by the potential influence of gestation on the pelvic articulations. A review of the modern literature reveals a perennial inquisitiveness equal to that of the ancients. Since 1920 no less than 200 publications have appeared on this subject. X-ray studies have engendered in recent years a renaissance of attention not only to the joints of the pelvis but also to greater precision in pelvimetry, the mechanics of pelvic inclination, cephalometry and the anthropologic significance of pelvic types. For over thirty years the roentgenogram has been used for pelvimetric studies, and such studies have culminated in the masterful work of Thoms,2 Jarcho, Caldwell,3 Moloy4 and others.
Interspersed throughout the many splendid contributions to osteology and mensuration of