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

Abstract

PurposesKnowledge 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.MethodsUsing 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.ResultsWithout 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.ConclusionsWith 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.

The Ratio of Clavicle Length to Head Circumference

“…The fitting equation we used supports a quadratic relationship between CL and GA. Consistent with previous studies which constructed nomograms of fetal clavicle by US 5,6 or CT, 2,7 we found that using high-resolution US allowed the visualization of the fetal clavicle in all 601 fetuses enrolled, from 12 gestational weeks onwards. In early studies, Yarkoni et al 6 measured the fetal clavicle and reported a linear relationship with menstrual age—the simple “1 mm = 1 week rule.” However, according to Sherer et al, 5 evaluation of 623 American fetuses between 14 and 42 gestational weeks proposed a new nomogram.…”

“…CL is dependent on different factors, including ethnicity, sex, age and body posture. 7 However, almost all data gathered to date to describe the normal ranges for CLs are available from almost exclusively Western literature, with little data coming from Asian populations. We undertook this prospective study to collect preliminary nomographic data in the form of CLs of healthy Chinese fetuses To form benchmark parameters.…”

“…Sherer et al 5 proposed a new nomogram of CL based on a larger sample of fetuses. In addition, 2 studies utilizing computed tomography (CT) to obtain the CLs of aborted human fetuses have demonstrated a correlation between fetal CL and the diagnosis of congenital defects 7 . Thus, there is promising evidence that CL measurement is a reliable and repeatable method which is positively correlated with gestational age (GA).…”

“…CL is dependent on different factors, including ethnicity, sex, age and body posture 7 . However, almost all data gathered to date to describe the normal ranges for CLs are available from almost exclusively Western literature, with little data coming from Asian populations.…”