The present invention relates to a method for planning the positioning of a ball joint prosthesis, in particular a hip joint prosthesis, wherein the prosthesis includes a stem and a cup and the method comprises the following steps: &mdashdetermining the position of at least one point lying on the rim of the joint socket, in particular the position of at least two points lying in an anterior region of the acetabulum &mdashdefining a requirement for the position and/or orientation of the cup on the basis of the determined positions of the at least one point. The present invention also relates to a method for optimizing the positioning of a ball joint prosthesis, in particular a hip joint prosthesis, wherein the prosthesis includes a stem and a cup and the method comprises the following steps: &mdashdefining at least one requirement for the position and/or orientation of the cup &mdashcalculating an optimum position and/or orientation of the cup on the basis of all the defined requirements being fulfilled.
