Measurement protocol. “CO”, tip of the coracoid; “CL”, inferior cortex of the clavicle; distance “CCD”, coracoclavicular distance measured between CO and CL; distance “A”, acromial thickness measured as the distance between the superior and inferior margin of the acromion; line “RL”, reference line at the inferior acromial cortex placed perpendicularly to A; distance “D”, distance between RL and the lowest and most lateral point on the clavicle measured perpendicularly to RL