A catheter assembly cooperates with a catheter lock enclosure having a base with an entry slot in an end wall. The catheter assembly has a flexible injection line extending from a base and an exterior tube surrounding the injection line and extending from the base. An exterior barrier extends radially outwardly from the exterior tube, and an interior barrier extends radially outwardly from the injection line and is spaced axially along the injection line from the exterior barrier. A gap is defined between the interior barrier and the exterior barrier, which receives the lock enclosure bottom part end wall to restrain the position of the catheter assembly with respect to the lock enclosure, and to restrict access to an interior of the catheter lock enclosure. The exterior tube and the interior and exterior barriers may be formed of high density polyethylene, or hard urethane, or Ultra-high-molecular-weight polyethylene (UHMW).
