Cross-sectional study of the ossification center of the C1–S5 vertebral bodies

PURPOSE: Knowledge on the normative growth of the spine is relevant in the prenatal detection of its abnormalities. This study describes the size of the ossification center of C1–S5 vertebral bodies. MATERIALS AND METHODS: Using CT, digital-image analysis, and statistics, the size of the ossification center of C1–S5 vertebral bodies in 55 spontaneously aborted human fetuses aged 17–30 weeks was examined. RESULTS: No sex significant differences were found. The body ossification centers were found within the entire presacral spine and in 85.5 % of S1, in 76.4 % of S2, in 67.3 % of S3, in 40.0 % of S4, and in 14.5 % of S5. All the values for the atlas were sharply smaller than for the axis. The mean transverse diameter of the body ossification center gradually increased from the axis to T12 vertebra, so as to stabilize through L1–L3 vertebrae, and finally was intensively decreasing to S5 vertebra. There was a gradual increase in sagittal diameter of the body ossification center from the axis to T5 vertebra and its stabilization for T6–T9 vertebrae. Afterward, an alternate progression was observed: a decrease in values for T10–T12 vertebrae, an increase in values for L1–L2 vertebrae, and finally a decrease in values for L3–S5 vertebrae. The values of cross-sectional area of ossification centers were gradually increasing from the axis to L2 vertebra and then started decreasing to S5 vertebra. The following cross-sectional areas were approximately equivalent to each other: for L5 and T3–T5, and for S4 and C1. The volumetric growth of the body ossification center gradually increased from the axis to L3 vertebra and then sharply decreased from L4 to S5. CONCLUSIONS: No male–female differences are found in the size of the body ossification centers of the spine. The growth dynamics for morphometric parameters of the body ossification centers of the spine follow similarly with gestational age.