Patent ID: 7677418

Claim:
A cartridge in which bone cement is mixed and from which bone cement is discharged, said cartridge including: a sleeve having opposed proximal and distal ends and that defines a mixing chamber that extends between the ends; a cap separate from said sleeve that is releasably secured over the proximal end of said sleeve, said cap having an orifice that opens into the sleeve mixing chamber; a piston slidably disposed in the sleeve mixing chamber, said piston having an outer perimeter; at least one lock tab separate from and slidably mounted to said piston so as to move from a locked state in which said at least one lock tab engages said sleeve to prevent proximal movement of said piston through the sleeve mixing chamber and a release state in which said at least one lock tab is spaced away from said sleeve so as to allow proximal movement of said piston through the sleeve mixing chamber; and a release button integral with said at least one lock tab and located inwardly from the piston outer perimeter, said release button having a feature shaped to be engaged by a ram such that when the release button is so engaged and the ram is moved toward said piston, said release button undergoes a displacement that moves said at least one lock tab from the locked state to the release state.