Background: The purpose of the study was an evaluation of fetal hip joint morphology during the second and the third trimester of pregnancy. Serial sections were performed on 23 cadaver infants.
Results: The mean lunar age was 6.6 months. Femoral shaft length (FSL) and width of the proximal and distal epiphysis were x-rayed to determine fetal age. The neck shaft angle (NSA), the femoral antetorsion angle (FAA), the acetabulum anteversion angle (AAA) and the acetabulum slope angle (ASA) were measured. Hip development ratios were plotted for all cadaveric species and revealed: flat FSL/NSA slope pattern, upward FSL/FAA slope pattern and downward slope pattern for FSL/ASA and FSL/AAA ratios. The changes, observed during the developmental period, were not statistically significant. NSA did not change during the second or the third pregnancy trimester. FAA increased during pregnancy but the changes were not statistically significant. AA, as well as ASA, showed a decreasing trend during the second and the third pregnancy trimester, however, with no correlations to age.
Conclusion: Despite an increasing depth and growing dimensions of the acetabulum in the uterus, its orientation does not change in any significant way.