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Table 2 Criteria for defining FAI types

From: Protocol for a multicenter prospective cohort study evaluating sport activity and development of femoroacetabular impingement in the adolescent hip

FAI typeCriteria
Cam1. Alpha angle is > 55°;
2. Anterior head-neck offset < 10 mm;
3. Anterior head-neck offset ratio < 0.15
*Must meet 2/3 criteria to be considered cam impingement
Pincer1. Acetabular depth < 3 mm;
2. Lateral centre-edge angle > 39°;
3. Acetabular anteversion (in the upper third of the femoral head) < 0°
*Must meet 2/3 criteria to be considered pincer impingement
Mixed*Must meet 2/3 criteria each for cam and pincer impingement (as per above) to be considered mixed impingement
  1. FAI Femoroacetabular impingement