It appears to be structural. He does need a trimming, his inside toe of the hoof longer longer than the outside toe, it may help a bit but it will never go away.
Start by trimming the toes even, then every couple of weeks take a shade off the inside. Don't try to do it in one big trim or you will have problems. Be easy and stay at it. You will not fix it 100 percent but you can get it better.