Acetabular index

The acetabular index is a measurement used to assess the anatomy of the hip joint in dogs, in particular the lateral slope of the acetabular roof. It is used to score coxofemoral dysplasia. The acetabular index is determined from a 2D CT images in a transversal plane. The dog is placed in dorsal recumbency with hip joints extended, adducted, and rotated slightly internally. Measurement is performed on three contiguous images that include an acetabular fossa, a well-defined acetabular sourcil, a round head of femur, and a fovea capitis.

The acetabular index is the ratio of the acetabular depth to the acetabular width multiplied by 100. The width is measured on a line drawn between the dorsolateral border to the ventrolateral border of the lunate surface. The depth is measured from the dorsomedial border of the lunate surface to the width line.

Lopez et al (2008) found that the acetabular index in adult mixed-breed dogs with laxity of the hip joints was 26,10 +/- 2,58° (range 11,10 - 35,30).

Andronescu et al (2015) published the following results for acetabular index in relation to osteoarthritis score:

• OA score 0: 31.22 ± 4.23

• OA score 1: 31.91 ± 3.42

• OA score 2: 34.16 ± 1.61

• OA score 3: 22.134 ± 8.66

Andronescu et al. (2015) published acetabular index in 46 dogs with all osteoarthritis scores combined at each age:

• 16 weeks of age: 30.63 ± 4.59

• 32 weeks of age: 32.16 ± 3.46

• 104 weeks of age: 28.02 ± 7.62