Measurement of the anterior head-neck offset (OS) and the anterior head-neck offset ratio (HNOR) on the Lauenstein pelvis projection of the patient in Figure 5OS is the distance between the lines c and b and is normally ≥10 mm. HNOR is the ratio OS/D and is normally >0.15. Right hip shows normal OS and HNOR but the left hip has post-SCFE FAI with pathologic OS and HNOR.SCFE: slipped capital femoral epiphysis; FAI: femoroacetabular impingement; a: axis of the femoral head; b: line on deepest point of the anterior surface of the femoral neck, parallel to a; c: line on the peak of the anterior contour of the femoral head, parallel to a; D: diameter of femoral head; R: right; L: left