When to worry an ankle sprain is a Lateral Process Fracture

I just saw a runner who sprained her ankle.  It's been about a month and she's still having pain. Pain and swelling persisting a month later, are not good. There are a couple of reasons that that can happen. 
 

Anytime doctors see persistent swelling and pain after an ankle injury, they become concerned there might be a fracture. 
 

When should a runner who rolled an ankle be concerned that there might be a fracture like a lateral process fracture? 
 

Well, that's what we're talking about today on the Doc On The Run Podcast.