An injection device (10) includes a syringe (12) having a body (14) with a piston (18) disposed therein with an open end. A needle assembly (26) is provided which includes a cannula (30) having a luer connection engageable with the syringe distal end with the luer connector including a hub. Mating engagement is provided by way of internal threads at the syringe distal end and external threads of a hub with a pitch sufficient to prevent detachment of the hub from the syringe distal end during ejection of fluid. In addition, a stepped cavity, disposed in the hub, further prevents detachment of the hub from the syringe distal end during ejection of fluid.
