What is periosteal elevation in tibial stress reaction?

When you get a stress fracture, one of the earliest visible indications on an X-ray or an MRI or a CT scan is a thing called periosteal elevation. Your doctor might see it on ultrasound, x-rays or MRI studies....way before your ever see a crack in the bone.  

Since it's one of the earliest changes in the bone when you start to get a stress fracture, I thought it might be useful to talk about the term "periosteal elevation" really means. 

What is periosteal elevation in a stress fracture in a runner? 

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