Three-dimensional growth of tibial shaft ossification in the human fetus: a digital-image and statistical analysis

Tibial shaft ossification in terms of its size and growth may be criticalin describing both the fetal stage and maturity, and in identifying innate disorders. The present study was executed to quantitatively assess ossification of the tibial shaft, taking its morphometric linear, planar and volumetric parameters into account.

With the use of methods of CT, digital-image analysis and statistics, the evolutionof tibial shaft ossification in 47 spontaneously aborted human fetuses at the age of 17-30 weeks was studied.

Without any male-female and right-left morphometric differences, the best fit growth dynamics fortibial shaft ossification was modelled by the following functions: y = 5.312 + 0.034 × (age)² ± 0.001 (R² = 0.89) for its length, y = - 2.855 + 0.307 × age ± 0.009 (R² = 0.96) for its proximal transverse diameter, y = - 0.758 + 0.153 × age ± 0.005 (R² = 0.88) for its middle transverse diameter, y = - 1.844 + 0.272 × age ± 0.09 (R² = 0.90) for its distal transverse diameter, y = - 40.263 + 0.258 × (age)² ± 0.007 (R² = 0.94) for its projection surface area, and y = - 287.996 + 1.186 × (age)² ± 0.037 (R² = 0.92) for its volume. The femoral-to-tibial ossification length ratio was 1.15 ± 0.1.

The size of tibial shaft ossification displays neither sex nor laterality differences. Tibial shaft ossification follows quadratic functions with respect to its length, projection surface area and volume, and linear functions with respect to its proximal, middle and distal transverse diameters. The obtained morphometric data of tibial shaft ossification are considered normative age-specific references of relevance in both the estimation of fetal ages and the ultrasound diagnostics of congenital defects.