[Theoretical principles of the cement-free prosthetic technic]

For long-term cementless fixation of prostheses compression stress transfer between bone and prosthesis is desirable. Shear stress and relative movement between implant and bone lead to bone resorption and implant loosening. A compression stress can be achieved by a suitable force transmission, a form-closed press fit and a suitable prosthesis surface. A ripped, rough or porous surface can transfer shear and tensile stress into compression stress at the interface. A force locking anchorage of the prosthesis can produce a prestressed fixation which supports the growing of the bone into the prosthesis surface. Stiff prostheses lead to a stronger stress protection and atrophy of the bone which favors the fatigue fracture of bone trabeculae.