Can I run if my fracture is not yet healed on x-ray?

I was just doing a call with a runner who started running before his fracture was healed on the x-ray. In fact his regular doctor said he couldn’t run on it until the x-rays showed healing. I let him start running on it, in a very structured way. Now he is back to full running. If the bone is always getting stronger while it is healing, do you really need to wait until the x-ray finally proves it has fully healed?  Today on the Doc On The Run Podcast, we're talking about whether or not you can run if you fracture is not yet healed on x-ray.