Quantitative anatomy of the growing clavicle in the human fetus: CT, digital image analysis, and statistical study.

PURPOSES: Knowledge of dimensions of fetal long bones is useful in both the assessment of fetal growth and early detection of inherited defects. Measurements of the fetal clavicle may facilitate detection of numerous defects, e.g., cleidocranial dysplasia, Holt-Oram syndrome, Goltz syndrome, and Melnick-Needles syndrome.

METHODS: Using the methods of CT, digital image analysis, and statistics, the size of the growing clavicle in 42 spontaneously aborted human fetuses (21 males and 21 females) at ages of 18-30 weeks was studied.

RESULTS: Without any male-female and right-left significant differences, the best fit growth models for the growing clavicle with relation to age in weeks were as follows: y = -54.439 + 24.673 × ln(age) ± 0.237 (R 2  = 0.86) for length, y = -12.042 + 4.906 × ln(age) ± 0.362 (R 2  = 0.82) for width of acromial end, y = -4.210 + 2.028 × ln(age) ± 0.177 (R 2  = 0.77) for width of central part, y = -4.687 + 2.364 × ln(age) ± 0.242 (R 2  = 0.70) for width of sternal end, y = -51.078 + 4.174 × ln(age) ± 6.943 (R 2  = 0.82) for cross-sectional area, and y = -766.948 + 281.774 × ln(age) ± 19.610 (R 2  = 0.84) for volume.

CONCLUSIONS: With no sex and laterality differences, the clavicle grows logarithmically with respect to its length, width, and volume, and linearly with respect to its projection surface area. The obtained morphometric data of the growing clavicle are considered normative for their respective weeks of gestation and may be of relevance in the diagnosis of congenital defects.