How can a diagnostic injection help heal an ankle sprain?

Let's say you are out running on a trail and you catch a root and you roll your ankle.  You limp back home and you realize that your ankle is all swollen. It is bruised, it hurts and you're really bummed out.  You are trying to figure out what you can do to get this thing to calm down faster and get back to running. Well, there are lots of different options. How can a diagnostic injection help an ankle sprain? Well, that's what we're talking about today on the Doc on the Run podcast.