Retaining element to prevent break loose contamination for partially pre-filled syringes

A syringe assembly comprising:

• a barrel including a side wall having an inside surface defining a chamber for retaining a predetermined volume of pre-filled fluid, wherein the predetermined volume of pre-filled fluid is substantially less than a total volume of the barrel,
• an open proximal end and a distal end including a distal wall with a tip extending distally therefrom having a passageway therethrough in fluid communication with said chamber;
• a plunger rod disposed within the barrel, the plunger rod comprising a distal end including a stopper having a distal face and a proximal end, a plunger rod body extending from the proximal end to the distal end, the plunger body being formed by two perpendicularly intersecting beams that intersect to form an outside surface outlining four quadrants that face the inside surface of the barrel and extend along the axial length from the proximal end to the distal end of the plunger rod;
• and
• one or more retention elements disposed on the plunger rod at a length from the distal end of the plunger rod configured to provide increased mechanical interference between the plunger rod and barrel when a force is applied in a proximal direction to prevent the pre-filled fluid from entering a non-sterile area of the syringe assembly, wherein the one or more retention elements comprise a first component and a second component disposed on and integrated into alternating crossbars, the first component of the retention element being in the shape of a “tear drop” and is integrated into a curved wall of the crossbar and comprises a first sloped surface, the first sloped surface outwardly tapers towards the distal end of the plunger rod body, the second component of the retention element is in the shape of a “submarine” and is integrated into a curved wall of an alternating crossbar and comprises a second sloped surface, the second sloped surface of the second component outwardly tapers towards the distal end of the plunger rod body.