The Ischiopubic ratio was used by Washburn to identify the gender in adult Americans. The pubic bone is longer in the female, while the length of the ischium is roughly proportional to the difference in size.
Patient population: 300 African and European Americans at the Hamann Museum at Western Reserve University
The initial step is to identify the point of juncture in the acetabulum of the ischium, pubis and ilium. This can be best seen by holding the bone up to the light.
Measurements (see Figure 28, page 112, Stewart):
(1) ischial line: from the point of juncture to the midpoint of the ischial tuberosity
(2) pubic line: from the point of juncture to the midpoint of the pubis, with the calipers held parallel to the long axis of the bone.
ischiopubic index =
= ((length of pubic line in cm) * 100) / (ratio of ischial line in cm)
Race |
Index |
Gender |
European American |
73 – 90 |
male |
|
91 – 94 |
indeterminate |
|
95 – 115 |
female |
African American |
71 – 83 |
male |
|
84 – 88 |
indeterminate |
|
89 - 106 |
female |
Thieme studied the index in African Americans from the Terry Collection. He found
(1) IP index < 85: male
(2) IP index 85 – 92, with femur head diameter >= 44 mm: male
(3) IP index 85 – 92, with femur head diameter < 44 mm: female
(4) IP index > 92: female
Performance:
• The index is able to correctly identify gender in over 90% of cases, but indeterminate cases occur.
• Performance is better if the race of the subject is known.
Specialty: Clinical Laboratory