The present invention relates to orthopaedic implants and has particular relevance to determining the placement of fixation apparatus or devices, such as screws, which are used to fix implants to the bone or bones with which the implants are to be connected. More particularly, the invention relates to a method for determining placement of a fixation apparatus for fixing an orthopaedic implant to bone, and the method comprising: selecting a plurality of fixation locations; using a bone density model to determine bone density associated with each location; and selecting a combination or permutation of the fixation locations dependent on the determined bone density.