Morphometric study of the two fused primary ossification centers of the clavicle in the human fetus

PURPOSES: A satisfactory understanding of the clavicle development may be contributing to both the diagnosis of its congenital defects and prevention of perinatal damage to the shoulder girdle. This study was carried out to examine the transverse and sagittal diameters, cross-sectional area and volume of the two fused primary ossification centers of the clavicle. METHODS: Using the methods of CT, digital-image analysis and statistics, the size for two fused primary ossification centers of the clavicle in 42 spontaneously aborted human fetuses at ages of 18–30 weeks was studied. RESULTS: Without any male–female and right-left significant differences, the best fit growth models for two fused primary ossification centers of the clavicle were as follows: y = −31.373 + 15.243 × ln(age) ± 1.424 (R(2) = 0.74) for transverse diameter, y = −7.945 + 3.225 × ln(age) ± 0.262 (R(2) = 0.78), y = −4.503 + 2.007 × ln(age) ± 0.218 (R(2) = 0.68), and y = −4.860 + 2.117 × ln(age) ± 0.200 (R(2) = 0.73) for sagittal diameters of the lateral, middle and medial ends respectively, y = −31.390 + 2.432 × age ± 4.599 (R(2) = 0.78) for cross-sectional area, and y = 28.161 + 0.00017 × (age)(4) ± 15.357 (R(2) = 0.83) for volume. CONCLUSIONS: With no sex and laterality differences, the fused primary ossification centers of the clavicle grow logarithmically in both transverse and sagittal diameters, linearly in cross-sectional area, and fourth-degree polynomially in volume. Our normative quantitative findings may be conducive in monitoring normal fetal growth and screening for inherited faults and anomalies of the clavicle in European human fetuses.