Acetabular and Femoral Orientation

Question 1

What is the normal acetabular version angle?

Answer 1

15-20°

Question 2

What does an acetabular angle > 20° mean?

Answer 2

decrease femoral head containment (retroversion)

Question 3

What does an acetabular angle < 15° mean?

Answer 3

It creates excessive femoral head coverage (anteversion)

Question 4

What is the cross over sign?

Answer 4

Posterior acetabular rim does not lie lateral to the anterior wall on AP view.

Question 5

What is the center edge angle (lateral) ?

Answer 5

frontal plane angle formed by a vertical line and a line connecting the femoral sourcil edge of the acetabulum.

Question 6

What is a pincer deformity?

Answer 6

> 39° is abnormal and an indication of a pincer deformity.
there is too much coverage on the pelvic side.
The labrum is subject to being damaged.

Question 7

Acetabular Inclination

Answer 7

Normal: 33° - 38
Dysplastic: > 47°

Question 8

Acetabular Index

Answer 8

Normal: 3-13°
Under Coverage: >13° (DDH)
Over coverage: <3° (pincer FAI)

Question 9

What does the Tonnis Angle measure and what is normal?

Answer 9

Measures angle of the weight-bearing surface.
Normal is 10°

Question 10

Center Edge Angle

Answer 10

Evaluates anterior coverage of femoral head by the acetabulum.
Normal : > 25°
Slightly abnormal : 20-25°
Severely abnormal : < 20°

Question 11

What is Coxa Profunda ?

Answer 11

lateral center edge angle is >35°
The socket is too deep

Question 12

What is acetabular protrusion?

Answer 12

The socket is to shallow

Question 13

What is a cam Impingement?

Answer 13

Femoral head/neck profile exceeds the radius curvature of the acetabulum.
Alpha angle > 60°