Table 5.

Alpha angle measurements in volunteers

Study	Number of volunteers	Alpha angle measurement	Mean alpha angle	Incidence of head-neck offset changes	Cut off value of head-neck offset changes
Nötzli et al. [29]	N = 40	MRI (axial plane through femur)	42.0° ± 2.2° (33°–48°)	Not assessed	Not assessed
Hack et al. [15]	N = 200	MRI (anterior and anterosuperior position)	40.9° ± 7.0° anterior 50.2° ± 8.2° anterosuperior	14% with at least one hip with changes	Alpha angle > 50.5°
Pollard et al. [34]	N = 83	Lateral radiograph	Not assessed	14.5% with at least one hip with changes	Alpha angle > 55°
Doherty et al. [8]	N = 1109	AP radiograph	Not assessed	3.61% with at least one hip with changes	Head-neck ratio < 1.27