How much trauma is needed to rupture your spleen if you don't have mono?

Splenic rupture: Splenic rupture usually occurs after blunt trauma. This includes a blow to the left lower rib cage, or a sharp stopping such as a car accident or a fall from a height.

Energy transfer: In addition to dr. Artuso's answer, the mechanism of energy leading up to the rupture is important. That energy transferred is how the injury occurs. Deceleration injury, penetrating injuries from projectiles, and blunt forces all cause splenic injuries. At this time, most splenic traumatic injuries can be managed without removal of the spleen.