[Postoperative pain in cement-free femur shaft prosthesis]

With practically all hip endoprosthesis systems the femoral components of which are implanted cement-free irritations in the femoral region persisting for up to two years p.o. have been reported significantly more frequently than with cemented shafts. The discussion of this observation is based on the fact that stems inserted cement-free are mostly press-fitted into the surrounding bone, thus, creating a completely different stress and strain field as compared to cemented shafts. The usually spontaneous disappearance of these initial irritations is attributed to remodelling reactions which, controlled by the load distribution in the surrounding bony tissue which, in turn, is mainly controlled by the shape of the prosthesis, results in the formation of well load bearing bony structures along steps and other surface undulations along the proximal part of the prosthesis.