One hundred anteroposterior roentgenograms of normal female pelves and 100 anteroposterior roentgenograms of normal male pelves were studied from the point of view of the interacetabular distance and the angle of inclination of the lateral pelvic wall.

Male pelves were characterized by a mean interacetabular distance of 25.9 centimeters, with a standard deviation of 1.7 centimeters. Female pelves were characterized by a mean interacetabular distance of 24.0 centimeters, with a standard deviation of 1.6 centimeters. No significant difference was found among the four fundamental pelvic types (android, gynecoid, anthropoid, and platypelloid) in the female subjects.

The mean angle of inclination of the lateral pelvic wall in male subjects was 211.4 degrees, with a standard deviation of 5.8 degrees. The angle of inclination of the lateral pelvic wall in female subjects was 206.4 degrees, with a standard deviation of 4.7 degrees. There was no significant difference among the angles of the pelvic wall in any of the four primary pelvic types.

The difference in mean interacetabular distance and the mean angle of inclination of the lateral pelvic wall between male and female subjects was statistically highly significant (P < 0.001).

It is suggested that there is no correlation between the distinguishing anatomical features of the interior of the true pelvis and those of the enterior of the pelvis here discused.

It is further suggested that the difference in clinical hip width among male and female subjects, respectively, is not due to the anatomical features of the true pelvis.

Data are presented for the statistically probable maximum and minimum amounts of apparent change in limb length which can be expected in virtually all patients following upper femoral osteotomy performed for unilateral disease of the hip joint.