[Extreme loading as cause of aseptic loosening of the total hip endoprosthesis socket and the resultant therapeutic consequences].

An analysis of the extent of damage in explanted endoprostheses of the hip showed massive destructions of the implanted components, such as fractures of the socket etc. For this reason, the authors designed a mathematical model of the extremity for which a prosthesis is designed; this model can simulate, inter alia, extreme loads of the joint occurring, for example, when a person falls. Self-experiments were helpful in determining the load exercised on the hip joint under such extreme conditions and in defining the effects on implanted joint material and the interface between bone and bone cement. Besides the influence of the body weight and the height of a fall, we also investigated dependence on attenuation promoted by different kinds of shoeware. These extreme loads in everyday life, which result in an excess stress of the materials and the interface, provide a good explanation for the aseptic loosening of the primarily well-fixed socket. From the therapeutic point of view these results suggest that such extreme burdening should be avoided during the time in which repair processes take place to gradually reduce the heat necroses in the osseous bed of the acetabulum which are due to the cement, by exercising a partial load only for three months after the operation rather than applying the full load too early. Attenuation of shock achieved by the use of various shoe materials was studied in self-experiments in which the researcher allowed himself to fall from different heights on to an outstretched leg while wearing different types of shoes.(ABSTRACT TRUNCATED AT 250 WORDS)