5 mm 10 mm 15 mm and 20 mm below the roof.
Normal acetabular roof angle.
Normal values in adults.
At birth it should be less than 28 degrees and should progressively reduce with maturation of the hip.
Thus the load in weight bearing is distributed across a smaller than normal bone surface area again resulting in labral tear and hip joint degeneration.
3 article feature images from this case.
Type 2 dysplasia short roof in type 2 dysplasia the angulation of the roof may be less than 10 but the roof is short providing less coverage of the femoral head.
Developmental dysplasia of the hip.
An acetabular index or roof angle of less than 10 is normal but more than 10 15 is considered dysplastic with higher risks of instability see graphic above.
An additional measurement of acetabular version was acquired at the center of the femoral head on each side.
The normal range is 33º to 38º.
Values between 3 and 13 are considered within the normal range 2.
The acetabular index also called acetabular roof angle or tönnis angle is a radiographic measurement of femoral head bony coverage by the acetabulum it is useful in assessing for developmental dysplasia of the hip ddh as well as pincer morphology in femoroacetabular impingement fai.
Additionally having the center beam above or below the pubis can alter the measurement due to geometric distortion.
The acetabular angle is a plain film measurement used when evaluating developmental dysplasia of the hip ddh which is measured between hilgenreiner s line and a line parallel to the acetabular roof.
Axial reformatted images through the acetabula were used to measure acetabular version angles at four locations with respect to the acetabular roof on each side.
A measurement between 39º and 46º is indeterminate.
Less than 39 42 and 55 of medial anterior and posterior acetabular roof arc angles involve absawba of the femoral head.
In this form the femoral head is well positioned but the acetabular roof is short and provides insufficient cover.
Standing lateral radiograph normal.
Physiologic acetabular anteversion angles in adults have been declared in the 12 to 20 range 5 7 but seem to be more variable 3 8 probably not least because of the dependence of the distance to the acetabular roof 3.
Acetabular angle defined as the angle made from line through the y synchondroses and another line through the superior and inferior points of the iliac portion of the acetabulum.
First a line is drawn running through the medial.
It is measured on ap pelvic radiograph.
Angles above 47º are seen in patients with acetabular dysplasia.
