We developed a method for the estimation of three-dimensional acetabular
coverage of the femoral head with use of only an anteroposterior radiograph
of the hip. This technique also allows recalculation of the corrected value
for coverage at neutral pelvic tilt. Provided that the acetabulum and
femoral head are spherical and congruent, the results are as accurate as
those obtained with computerized tomographic reconstruction, the dose of
radiation is much lower, and much less time is required for calculation.
The hips of 286 normal subjects showed increases with age in both anterior
and posterior coverage and backward tilt of the pelvis, along with a
decrease in the anterior-posterior ratio of coverage. The proportion of
anterior acetabular coverage in female subjects was smaller than that in
male subjects. There was more backward tilt of the pelvis and the
anterior-posterior ratio of coverage was smaller when the subjects were
standing than when they were supine.