Reduction of the development of stripe wear on inserts for hip joint prostheses by modifying the geometry of the transition between the face and spherical recess

EKA socket insert of a hip joint prosthesis having a spherical-indentation-shaped recess in which a spherical head of a femur is mounted. The spherical indentation has a run-in zone which ends on one side with a circular arc tangentially in an end face of the socket insert and extends on another side as far as the run-in edge. Between a start of the circular arc with a radius of the length (R) and the run-in edge of the spherical indentation with the radius of the length (R) the run-in zone forms a curve, the function of which is continuously differentiated twice at every point.