A needle assembly for dispensing a bone cement mixture is provided. The needle assembly includes a cannula defining an inner lumen, the cannula having an outlet end for dispensing the bone cement mixture from the assembly. The outlet end has at least one tip moveable between an expanded position and a collapsed position. The tip is configured to cut the bone cement mixture in the collapsed position when the cannula is rotated. The needle assembly also has an inner member disposed within the inner lumen of the cannula, which is movable between an extended position and a retracted position. The inner member is operable to hold the tip in the expanded position when the inner member is in the extended position. The tip automatically collapses into the collapsed position when the inner member is in the retracted position. A method of introducing a bone cement mixture into a damaged bone of a patient is also disclosed.
