The morphological and pathological significance of synostosis at the manubrio-sternal joint.

Acceptedteaching concerning the time and nature of synostosis of the manubrio-sternal joint is, generally speaking, erroneous. In agreeing with Fallopius and Eustachius, Coiter (1573) showed justifiable caution in stating that synostosis of this joint appears at the time at which the cranial sutures begin to be obliterated. This, of course, can mean any time after 30 years. Anatomists of the seventeenth and eighteenth centuries (Crooke, 1615; Highmore, 1651 ; Bartholinus, 1668; Bidloo, 1685; Weitbrecht, 1742; Winslow, 1756; Monro Primus, 1758) were more definite, but less justified, in stating that the sternum is " not one bone, unless it be in very old men " (Crooke). Despite a steadily growing mass of evidence which shows that fusion at this joint is a phenomenon by no means peculiar to old age, modern textbooks still adhere to the old teaching. For example, one may quote Latarjet (1928), who states that fusion of the manubrium and body of the sternum occurs "dans l'extreme vieillesse seulement"; Johnston and Whillis (1949) say that it " occasionally becomes ossified in advanced life "; Jones (1949) that " the manubrium usually remains permanently separate unless in advanced life, when it may become ankylosed to the body"; and Walmsley (1951) that, (infrequently) " the joint is obliterated by synostosis in old age." However, at least one modern anatomist (Grant, 1944) gives credit to Trotter (1934), who found from study of 877 sterna that there is " no correlation . . . between the incidence of synostosis and age." Even before Trotter published her findings evidence had accumulated to show the fallacy of the accepted teaching concerning this joint. Paterson (1904) in his monograph stated, " It [synostosis] occurs in 8.8% of the 642 sterna examined. Its frequency increases with age. Fusion occurs in 3.1 %1, of sterna under 30, in 10.5% between 30 and 49, and in 15.6% between 50 and 82. At the same time it is not altogether a senile condition. Among 46 sterna between 61