[Roentgenologic determination of maturity in low birthweight infants].

121 infants with low birthweight and a well known gestational age were divided into four groups: preterm infants, small for gestational age (SGA) infants, appropriate for gestational age (AGA) infants and infants with Clifford syndrome. With the 100 mm spot film technique X-rays of the right knee and ancle of the infants were taken and the size of the epiphyseal centers of the distal femur, the proximal tibia, the talus and the calcaneus was measured. The mean organ dose of the leg was only 2 mrad. All epiphyseal centers examined showed an increase from the 33rd to the 42nd week of gestation, which is in good agreement to previous studies. There was no evidence of a statistical difference of epiphyseal size between the four examined groups of neonates of low birthweight. Thus, in the present material with very close mean birthweights of the four groups, we were unable to distinguish preterm born infants from SGA infants with this method alone. This result suggests, that bone age is a more resistant criteria to fetal malnutrition than mass growth.