He is a False Map turtle,
Graptemys pseudogeographica pseudogeographica.
He will lose more scute and bone from under the first coastal and the first vertebral scutes (not all of it but some). He should also be shedding all his scutes at least once a year. The top layer of the scute is shed every year.
That said he is still just fine as it's already healed and just in the process of coming off. This has been healing for at least a year (if not longer).
Danny