Periprosthetic bone adaptation around orthopaedic implants can be studied with Finite Element models. It requires a comparison between the mechanical status of the bone in the operated (unnatural) situation and the natural situation. The difference between these two situations is the alteration in mechanical condition of the bone, which is assumed to be the driving force of the adaptation process. The time dependent bone adaptation process can be simulated with a computer algorithm by an iterative (time stepping) procedure. This study reviews some clinical and experimental issues, it addresses the value of computer models of periprosthetic bone adaptation and discusses a new development of voxel based models directly converted from CT scans.