insertion position of the replacement intervertebral disk 12 longitudinal axes of the mutually associated blind hold bores 40 in identical edges of both end plates 14 and 16 define in each case one plane the insertion instrument 10 comprises an elongate tubular sleeve 42 which defines a longitudinal axis 44 in longitudinal direction of the insertion instrument 10 at the proximal end the sleeve 42 is connected in a rotationally fixed manner to a rotary sleeve 46 which is provided with an internal thread 48 the sleeve 42 penetrates a shank 50 that is provided with a central longitudinal bore 52 a blind hole bore 54 which at the distal end widens the longitudinal bore 52 in the shank 50 is provided with an internal thread that is connected to an external thread of a threaded bolt 56 which is directed integrally with a holding fork 58 in proximal direction the holding fork 58 adjoining the threaded bolt 56 is of a rod shaped design but is provided along over half of its length at the distal end with a slot 60 for forming a top and a bottom fork end 62 and 64 both the threaded bolt 56 and the adjoining non forked portion of the holding fork 58 are provided with a bore 66 that is a continuation of the longitudinal bore 52 to facilitate a springing of the fork ends 62 and 64 these are.