51 巻 (1976) 4 号 p. 109-115
Radiological observation was made on the ossification of human rib cartilage. Approximately 1/25 random sample of normal chest radiogrammes taken during the tuberculosis prevalence survey in 1968 was interpreted by the author with special reference to the ossification of rib cartilage, and the prevalence and grade of ossification were analyzed in relation to age, sex and geographical region. The results were summarized as follows:
1) The ossification of rib cartilage was seen far more frequently and intensively in the first rib. Concerning the other ribs, the ossification was least in the second rib, and it was similar in the third, fourth, fifth and sixth ribs. The interpretation of ossification of rib cartilage was often rather difficult in the seventh rib and thereunder.
2) The ossification of the first rib cartilage was seen in the earliest case at the age of 16, and it was observed in nearly all cases in the age groups 30 and over. There was no marked difference in the prevalence of persons with ossified rib cartilage between sex, while the grade of ossification was much more marked in male than in female in the age groups 30 and over. The higher the age, the more intensive the grade of ossification.
3) In the case of the second rib, the ossification was seen in less than 10% in the age group 30 to 39, and it was 43% in male and 14% in female in the age group 60 and over.
4) In the case of fifth rib, the ossification was seen in 65% of male and 33% of female in the age group 60 and over, and it appeared faster and more intensive in male than in female.
5) No significant difference was found in the prevalence and grade of ossification of rib cartilage among northern, central and southern regions of Japan.