Alpha angle (cam morphology)
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At the time the article was created Yuranga Weerakkody had no recorded disclosures.View Yuranga Weerakkody's current disclosures
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The alpha angle is a radiological measurement proposed for the detection of cam morphology, which is sometimes associated with femoroacetabular impingement (FAI).
Measured on obliquely oriented radiographs. The Dunn projection of the hip is used.
Measured on oblique axial images as the angle between 4:
- a line from the center of the femoral head to the center of the femoral neck at its narrowest point
- a line from the center of the femoral head to a point where the distance from the bone to the center of the head is greater than the radius of the cartilage-covered femoral head
There is no one value that can define cam morphology 5. Initially, in 2002, an alpha angle of ≥50° was proposed as pathological 4, subsequently, a value of ≥57° was proposed in symptomatic patients 2, and more recently (c. 2021) a value of ≥60° has been proposed as definitional of cam morphology 5.