The invention relates to a vacuum mixing system for the mixing ofpolymethylmethacrylate bone cement comprising at least one cartridge (4)having anevacuatable internal space (5) for the mixing of the bone cement, whereby theinternal space (5) comprises a cylindrical swept volume, a mixing element (12)that isarranged in the internal space (5) of the cartridge (4) such as to be mobileand can beoperated from outside the vacuum mixing system in order to mix the content intheinternal space (5) of the cartridge (4), and a dispensing plunger (2) having acylindrical external circumference whose first base surface borders a basesurface ofthe internal space (5) of the cartridge (4) and which can be or is locked tothecartridge (4) in detachable manner and which, in the detached state, is mobilein thecylindrical region of the internal space (5) of the cartridge (4), whereby agas-permeableand particle-impermeable feedthrough (1) is arranged in the dispensingplunger (2) or a feedthrough (1) is formed between the dispensing plunger (2)and theinternal wall of the internal space (5), whereby the feedthrough (1) extendsfrom anopening in the jacket surface of the dispensing plunger (2) to an opening inthe firstbase surface of the dispensing plunger (2).The invention also relates to a method for the mixing ofpolymethylmethacrylate bonecement in a cartridge (4) of a vacuum mixing system.
