New patterns of the growing L3 vertebra and its 3 ossification centers in human fetuses – a CT, digital, and statistical study

BACKGROUND: This study describes reference data for L3 vertebra and its 3 ossification centers at varying gestational ages. MATERIAL AND METHODS: Using CT, digital-image analysis and statistics, the growth of L3 vertebra and its 3 ossification centers in 55 spontaneously aborted human fetuses aged 17-30 weeks was examined. RESULTS: Neither sex nor right-left significant differences were found. The height and transverse and sagittal diameters of the L3 vertebral body increased logarithmically. Its cross-sectional area followed linearly, whereas its volume increased parabolically. The transverse and sagittal diameters of the ossification center of the L3 vertebral body varied logarithmically, but its cross-sectional area and volume grew linearly. The ossification center-to-vertebral body volume ratio gradually declined with age. The neural ossification centers increased logarithmically in length and width, and proportionately in cross-sectional area and volume. CONCLUSIONS: With no sex differences, the growth dynamics of the L3 vertebral body follow logarithmically in height, sagittal and transverse diameters, linearly (in cross-sectional area), and parabolically (in volume). The growth dynamics of the 3 ossification centers of the L3 vertebra follow logarithmically in transverse and sagittal diameters, and linearly (in cross-sectional area and volume). The age-specific reference intervals of the L3 vertebra and its 3 ossification centers present the normative values of clinical importance in the diagnosis of congenital spinal defects.