The fetal acetabulum. A histomorphometric study of acetabular anteversion and femoral head coverage.

To study the development of the acetabulum in the early fetal period, 39 embryologic specimens were reviewed in detail. Histologic serial sections were made through 47 hips in the transverse plane. Measurements of acetabular anteversion and femoral head coverage revealed that both parameters depend on the exact level of sectioning. However, when measured at the level of the maximum diameter of the femoral head, they did not show significant variation through the embryonic and early fetal stages (six to 20 weeks). This is in contradistinction to the late fetal period. The hip does remain covered during this early fetal period. Congenital dislocation of the hip is not an early developmental condition. This accounts for the absence of any reports of hip dislocations in the first half of gestation.