DETERMINATION OF ACETABULAR COVERAGE OF THE FEMORAL-HEAD WITH USE OF A SINGLE ANTEROPOSTERIOR RADIOGRAPH - A NEW COMPUTERIZED TECHNIQUE

We developed a method for the estimation of three-dimensional acetabul ar coverage of the femoral head with use of only an anteroposterior ra diograph of the hip. This technique also allows recalculation of the c orrected value for coverage at neutral pelvic tilt. Provided that the acetabulum and femoral head are spherical and congruent, the results a re as accurate as those obtained with computerized tomographic reconst ruction, the dose of radiation is much lower, and much less time is re quired for calculation. The hips of 286 normal subjects showed increas es with age in both anterior and posterior coverage and backward tilt of the pelvis, along with a decrease in the anterior-posterior ratio o f coverage. The proportion of anterior acetabular coverage in female s ubjects was smaller than that in male subjects. There was more backwar d tilt of the pelvis and the anterior-posterior ratio of coverage was smaller when the subjects were standing than when they were supine.