Absence of lower extremity ossification centers in term infants with congenital syphilis.

Radiologic evaluation is valuable for confirmation of congenital syphilis. Bony abnormalities are thought to be secondary to active disease or a growth response of bone to systemic illness. Anteroposterior lower extremity radiographs of 85 euthyroid term infants (> or = 38 weeks' gestation; mean weight, 3244 gm; range, 1940-4380 gm) with presumptive congenital syphilis were evaluated for the presence of the distal femoral and proximal tibial secondary ossification centers and other bony abnormalities. Both proximal tibial and distal femoral ossification centers were absent in only 9 of 85 infants with syphilis; the proximal tibial center was absent in 26 of 85 (total 30.6%; 95% confidence limits 0.2 to 0.4). This observation is significant at the p < 0.01 level by chi-square analysis with use of historical controls. Periosteal new bone formation was seen in 2 of 85 infants. Metaphyseal lucent bands were present in 21 of 85 infants, 8 of whom also had absent lower extremity ossification centers. For comparison we reviewed lower extremity radiographs from 12 term infants without congenital syphilis. Ossification centers were absent in one growth-retarded infant, and metaphyseal lucent bands were found in one infant. Although standard texts report nearly universal ossification of the distal femoral epiphysis at term, we observed delayed skeletal maturation in 30.1% of term infants with congenital syphilis. We speculate that this delay may be reflective of systemic infection.