A method for mixing and injection and an apparatus for performing the method includes the use of a needle and a needle base, a syringe attachment element and a mixing chamber engagement assembly including a needle chamber surrounding the needle and a first liquid conduit portion, sealed from the needle chamber. A mixing chamber engagement portion includes a second liquid conduit portion communicating with the first liquid conduit portion and a mixing chamber. When the syringe attachment element and the needle base are in a first relative engagement orientation liquid can flow between an interior of the syringe and the first liquid conduit portion and upon axially displacing the needle base and syringe attachment element to a second relative engagement orientation, liquid can flow between an interior of the syringe and the needle.