What is a posterior process talus fracture?

I just had a discussion with a runner during a telemedicine second opinion.

She rolled her ankle and went to the emergency room. They gave her a brace to stabilize the ankle and an ACE wrap to compress it. 

She started some rehab exercises, and frankly she improved a lot.  

But when she got back to running, she had intermittent pain in the back of her ankle.

This was not the same spot where she got the sprain. 

She called because this pain has now been going on for a long time, and when she got an x-ray someone told her she might have a posterior process fracture of the talus. 

She asked me, "What exactly is a posterior process fracture?"

Today on the Doc On The Run Podcast we're talking about posterior process fractures of the talus.