"Missing" sternal ossification center: potential mimicker of disease in young children

To evaluate the frequency of "missing" sternal ossification center (asynchronous non-ossification) in young children.

Lateral chest radiographs obtained in 229 children (mean age, 3.7 years) were retrospectively evaluated for sternal ossification. Four superior sternal segments were considered normal if they were ossified to a similar degree. A segment was considered asynchronous if decreased ossification, as compared with the remaining sternal segments, was demonstrated or if ossification was absent. Asynchronous ossification of inferior sternal segment 5 was recorded separately. Logistic regression analysis was applied to determine if there was a statistically significant relationship (P <.05) between age or sex and pattern of sternal ossification (normal vs asynchronous).

Of the 916 superior four sternal segments (four segments in each of 229 patients) evaluated, 32 (3.5%) showed asynchronously decreased or absent ossification. Locations of these 32 segments follow: segment 1, two (0.2%) instances; segment 2, 14 (1.5%) instances; segment 3, two (0.2%) instances; and segment 4, 14 (1.5%) instances. Inferior segment 5 was not ossified in 73 (31.9%) patients. There was a statistically significant relationship between decreased age and increased likelihood of occurrence of asynchronous ossification of one of the sternal ossification centers 1-4 (P >.003) and of occurrence of asynchronous ossification at sternal segment 2 (P <.018).

Missing sternal ossification centers occur most commonly at segments 2 and 4. Such asynchronous non-ossifications become less common in older children.