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Table 1 Criteria for defining FAI

From: Prospective evaluation of sport activity and the development of femoroacetabular impingement in the adolescent hip (PREVIEW): results of the pilot study

FAI type

Criteria

Cam

☐ Alpha angle is > 55°

☐ Anterior head-neck offset < 10 mm

☐ Anterior head-neck offset ratio < 0.15

*Must meet 2/3 criteria to be considered cam impingement

Pincer

☐ Acetabular depth < 3 mm

☐ Lateral center-edge angle >39°

☐ 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