Femoro-acetabular impingement cam-type - with alpha angle measurements
Diagnosis almost certain
Presentation
Pain in both hips.
Patient Data
Age: 50 years
Gender: Male
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Bilaterally there is appreciable bone production between the femoral head and neck (bump) with loss of sphericity.
Osteoarthritis with joint space narrowing and osteophytes in the lower margin level of the head.
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The angle alpha is 85° to the right and 84° to the left.
Case Discussion
To calculate the alpha angle first find the center of the epiphysis then track axis through femoral neck to the center of the epiphysis, and then the circumference of the curvature radius at the point where the epiphysis profile moves away from the circle to become neck.
Alpha angle in the normal hip is < 50°. In cam-type FAI the alpha angle is >50°.
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