[Diagnosis for the localization of cemented intramedullar stem prostheses and ICLH-prostheses of the hip by means of stereo X-ray prints (author's transl)].
It is known that the loosening of artificial hip joints leads to their shift relative to the carrying bone structure. For a quantitative radiological detection of even minimal dislocations fix-points both in the carrying bone structure as well as in the prostheses have to be defined. While for the stem prostheses and cups such points can be defined directly from their geometrical structure, they have to be generated artificially for the carrying bone structure by implanted metal pins, which can easily be detected in the X-ray print. Having defined in this way a complete and appropriate set of fix-points, the position of the prosthesis relative to the bone structure is uniquely defined by the distance vectors between the different fix-points. The main biometrical steps of such a concept as well as their computational formulation and realization are derived; the main advantages and the accuracy of the technique are elucidated and critically discussed.