Apparatus for mixing a two part cement of a type adapted for fixing a repair element to hard, rigid tissue of a patient and containing the mixed cement preparatory to dispensing for such fixation. A mixing chamber has an outlet for mixed cement. A cartridge has an inlet releasably coupled to the outlet of the mixing chamber for receiving mixed cement therefrom. A rotating blade in the mixing chamber mixes cement, removes voids therefrom and moves mixed cement off the inner surface of the mixing chamber and into the cartridge.