Do a search on knee chips and you will find that this will usually bother them when put to reg. work. He will most likely be fine as a trail horse but don't expect to do any hunter/jumpers. Not saying he's gonna be a bad horse, but the only way to get him to a good status is possilby having surgery to remove the chip. I've personally never heard of a chip working itself out, just settling. I would ask for the radiograph images. Then go from there. Many horses have this injury and continue to have good lives, but plan on supplements and such for his comfort, etc.