 For the forearm scan, the participant is seated in a chair at the side of the pQCT unit. The participant sits as close as possible to the unit. The shoulder should be close to the front side of the gantry. The armrest of the machine is adjusted to the measured forearm length. The elbow is fixed at the corner of the armrest with the Velcro strap and the distal forearm is fixed with the clamp. The angle between upper arm and forearm should not exceed 90. The hand lies on the hand rest. The fixation of the arm should prevent movement artifacts but must not hurt. The participant is asked to search for a convenient and natural position to avoid movement or discomfort during the scanning period of 3-5 minutes. 