There is the whole fusing his spine together thing.
On that topic, I spoke with a friend who is a doctor and he talked about spinal fusion and how it's not a permanent fix and that it's degenerative. He said it would be hard for Peyton to have the surgery again on the same vertebrate in the future, and that what's fusing the spine (usually screws, metal plates, rods) will wear down the bone. Eventually he will have limited mobility in his neck, especially turning from side to side. It was a depressing conversation.