It's debated because there is no "void." If you hit above the vitals you're either hitting spine or meat.

It sounds like you hit him in the spine, but didn't break the spine. I've seen that before where a broadhead will smack the vertebrae and break the arrow off but not break the spinal cord. I've also seen where a shot like that will knock a deer off it's feet and then they get up and run off. The good thing is you know he is still out there and alive.

Good luck getting back on him.