In a method for determining the pelvic inlet plane of the pelvic bone, which is defined by the following three points of the pelvic bone:point A: spina iliaca anterior superior leftpoint B: spina iliaca anterior superior rightpoint C: symphysis pubis,by non-invasive determination of the position of one of the two points A or B and point C, in order to also be able to carry out this determination whenever point A or point B is not accessible, it is proposed that the position of the following points of the pelvic bone be additionally determined non-invasively:point D: spina iliaca posterior superior leftpoint E: spina iliaca posterior superior right,and that the position of the pelvic inlet plane be calculated from the position of the non-invasively determined points A or B, C, D and E.
