The invention relates to an operation system for a joint prosthesis, in particular a shoulder joint prosthesis, having two cooperating bearing bodies, in particular a joint head and a joint shell, a shaft and a coupling to connect the shaft to one of the bearing bodies comprising a positioning device by means of which the shaft can be positioned at a desired depth in the bone without a coupling, a prefixing device by means of which the desired position of the bearing body relative to the coupling can be pre-fixed at the shaft positioned at the desired depth; and a final fixing device by means of which, with the coupling removed from the shaft, the pre-fixed desired position can be finally fixed.