Femoroacetabular impingement is a common anatomical finding in ballet dancers. Cam morphology and an increased alpha angle are risk factors for pain in the hip.
Traditionally the alpha angle is measured on lateral radiographs, or on oblique axial slices on MRI. More recently the angle has also begun to be assessed by ultrasound.
A new study set out to investigate the effect of the alpha angle measured by ultrasound on the hip and its effect on functional tests in high-level ballet dancers.
The angles of 25 dancers, of mean age 15.9 years, were measured using ultrasonography. Cam morphology was defined as an alpha angle > 60°. The participants in the study scored their hip pain and function using the International Hip Outcome Tool 12 (iHOT-12).
The researchers concluded that the alpha angle can have a significant adverse effect on hip pain and function, and that when it exceeds 60° it causes a worsening of symptoms in these athletes.
Source: “Journal of Dance Medicine and Science”, September 2020