A study of the ossification centers of the wrist, knee and ankle at birth, with particular reference to the physical development and maturity of the newborn

Abstract 1.1. The inferior femoral epiphysis, judging from all available data, is present in about 1 case in 20 in the eighth fetal month, in 1 case in 3 in the ninth month, in 6 cases in 7 in the tenth month, and in about 19 cases in 20 at birth (full-term infants). If not present at birth, the center appears before the close of the first postnatal month. In our own series the center was present in 98 per cent of all newborn children. 2.2. The superior tibial epiphysis, judging from all available material, is almost never present before the ninth fetal month. It is found in 1 case in 17 in the ninth month, about 2 cases in 5 in the tenth month and in about seven-eights of all full-term newborn children. It was present in 81 per cent of the cases in our series. 3.3. The cuboid, according to all available data, first appears at about the beginning of the ninth fetal month. It is present, on the average, in about 1 case in 25 in the ninth month, in about 1 case in 4 in the tenth month, and in about 3 cases in 5 in full-term newborn children. In our own series the center was present in a much smaller per cent of all cases than is reported by other investigators (38 per cent). 4.4. Two carpal ossification centers, those of the os capitatum (os magnum) and of the os hamatum (unciform), may be present in the newborn. In our series the os capitatum was present in 15 per cent and the os hamatum in 9 per cent of all cases. 5.5. There is a close relation between total body-length and frequency of ossification of the several centers discussed in this paper. A similar, but less close, correlation exists between frequency of ossification and the body-weight. 6.6. In our material the correlation of body-weight, total body-length and frequency of ossification with menstrual age was quite close for the middle members of the series ranging in menstrual age from 270 to 300 days. But the outlying cases (having a menstrual age of less than 270 or more than 300 days) show little relation between these measures of bodily development and age as determined from the menstrual history. 7.7. Our evidence points to the conclusion that ossification proceeds slightly more rapidly in females than in males during intrauterine life even though the weight and dimensions of the females are less than those of the males. 8.8. Our observations show no direct evidence of any relation between parity and the rate of ossification in intrauterine life. 9.9. Variations in the number of ossification centers present for individual bones were limited to the os capitatum and os cuboideum. The latter is formed from an extremely variable number of centers. When anomalies in the number of centers are present they are often asymmetrical. 10.10. Variations in the order of appearance of centers were decidedly unusual in our material, being confined to premature ossification of the os cuboideum (2 cases) and of the premature ossification os capitatum (2 cases). 11.11. The usual order of appearance of the centers under consideration is as follows: (a) Inferior femoral epiphysis; (b) Superior tibial epiphysis; (c) Cuboid; (d) Os capitatum; (e) Os hamatum.