Needle assembly having locking enclosure

摘要

A shield assembly (10) is provided for a needle cannula (36) of a hypodermic syringe (12). The shield assembly (10) includes inner (42) and outer shield (44). The inner shield includes a guard (46) selectively movable between a proximal position which permits use of needle cannula and a distal position which safely covers the tip (40) of the needle cannula (36). The outer shield (44) is frictionally and removably positioned over the needle cannula when the inner shield (42) is in its proximal position. Movement of the inner shield to its distal shielding position enables alignment of cooperating locking structure (56,66) on the inner shield and outer shield with one another for permanently securely locking the outer shield (44) over the needle cannula (36).