[Effect of form elasticity of the prosthesis shaft in response to stress of the proximal femur].

Uncemented hip prostheses are characterized by a variable design of the stem. In these investigations, nine different prostheses were studied according to the model of a standard bone (Kunststoffnormfemur). After preparation of the cavity of the prostheses with original instruments and after its implantation, strain gauges were placed at 16 certain points. Measurements were carried out in steps of 200 N until reaching the maximal force of 2kN. Prostheses that are characterized by an anatomical design of the stem resemble the physiological nature of normal bone, in contrast to the models with a rectangular cross-section or with a stretched lateral shape of the stem.