the femoral bone - hip joint endoprosthesis comprises a shank 10 , an articular spheroid 30 and an articular fossa 40 , in which the articular spheroid is connected to the shank 10 by means of a double cone plug connection 20 . in the fig2 and 4 , a femoral shaft , into which the shank 10 with the endoprosthesis is implanted , is identified with f . in the upper end 10a of the shank 10 , a cavity 11 is constructed in the same which , depending on the respective selected anatomical shape of the shank 10 , possesses an appropriate form and suitable dimensions . if possible , this cavity 11 should extend as far into the shank 10 as possible , however , without the strength of the shank being in any way impaired or diminished thereby . the circumferential rim 12 of the shank 10 delimiting the upper cavity aperture 11a of cavity 11 is inserted into the cavity 11 while forming a collar - like and tubular retaining stud ( 15 ) ( fig2 and 4 ). in this case the length of the retaining stud 15 is selected in such a way that a firm fit of a double cone 120 of a plug connection 20 inserted into the retaining stud 15 is ensured without any internal cavity space being lost in the process or the stability of the wall delimiting the cavity being impaired . the retaining stud 15 , which serves to accommodate the double cone 120 , according to an embodiment of the invention , possesses an internal cavity 17 which extends conically toward its free end 15a , so that the retaining stud 15 may be provided with an outer profile which is constructed in any way whatever or which possesses an outer wall shape constructed in any way whatever in order to , by way of example , so as to enable an additional support of the retaining stud 15 to be effected relative to the inner wall area delimiting the cavity 11 . furthermore , the retaining stud 15 possesses an oval internal cross - section which is identified with 16 in fig5 and 6 . the double cone 120 , too , exhibits , at least within its terminal retaining stud insertion area 121 , a shape and , more particularly , a cross - sectional configuration , which corresponds to the internal cross - sectional configuration of the retaining stud 15 , so that the double cone 120 likewise has an oval cross - sectional configuration . the respective other end 122 which serves to accommodate the articular spheroid 30 , likewise exhibits an oval cross - sectional configuration , however , also other cross - sectional configurations are possible , in which case such cross - sectional configurations have to be selected in each instance which correspond to the cross - sectional configuration of the cone insertion aperture in the articular spheroid 30 . according to a further embodiment of the invention , the tubular retaining stud 15 inserted into the cavity 11 of the shank 10 , while the wall thickness extending over the entire length of the retaining stud 15 is maintained so as to be uniform , tapers off conically in the direction of its free end 15a ( fig2 and 4 ). due to this design , a high degree of elasticity of the retaining stud 15 relative to the delimitation wall of the cavity 11 is achieved .
the femoral bone - hip joint endoprosthesis is characterized by the cavity construction of the prosthesis shank , by the ovaloid - conical aperture of the prosthesis shank and by the ovaloid - conical aperture of the upper prosthesis shank end for the accommodation of a cone plug connection .