COMPARABLE EXAMINATIONS FOR THE RIGIDITY- BEHAVIOR, DEFORMATION-BEHAVIOR AND ABSORPTION-BEHAVIOR OF DIFFERENT ARTIFICIAL HIP-JOINTS UNDER DYNAMIC LOADS

The biomechanic al reasons for moving and loosening of the acetabular cup and femoral prothesis are still unclarified. Especially chronical and mechanical overloads of the interfaces, which are caused in the ch ange of stiffness-and damping-properties of the whole system, cannot b e excluded. Up to now, the description of dynamic behaviour of hip-joi nt endoprotheses under the aspects of material-selection and design, i s still unsufficient. On the bases of comparable experiments this publ ication aims to complete the knowledge about mechanical properties of artificial hip-joints. Primary the interests were focused on the quant itative coverage of certain influences (e. g. design, dimensions and m aterial) on the dynamic properties of different kinds of acetabulum cu ps. Therefore, a significant new test-method was developed for this ex amination. Conventional test-methods are working according to the prin ciple in constancy of maximum-forces and exciting-frequencies. They do not consider the forces of inertia resulting out of the bodymass. Eve n though these reaction-forces are desisive for the dynamic properties and mechanical behaviour of the components of endoprotheses. A select ion of representative implants of several manufactures was tested acco rding to the new test-method, which is based on the ''mass-, spring-, absorber''-principal. The examined protheses were different from each other, because of the material, the method of fixation and their geome tric dimensions. The results of these examinations give clues concerni ng the repercussions of the mentioned parameters relating to the dynam ic behaviour of endoprothetic systems. In order to evaluate the result s also hip joints from animals were examined and give relevant informa tion for desirable alternative solutions of the problem in view of con struction and material.