When I wrote the owner of this horse this is what they wrote back...
Apollo hasn't had any injuries that we are aware of. We are a therapeutic riding center and he was donated in 2011. He was never solid enough to make it into our program and has been hanging out needing a new home for awhile now. He has excellent ground manners and can be handled by anyone but under saddle, he needs someone with a little experience as his TB side comes out every now and then. He shows all the signs of the wear and tear you would expect an 18 year old jumper to have. He is not 100% sound but we are not able to invest money in a horse we can't use so I think there are things you could try to get him sound- ie injections, legend, joint supplement, etc. We radiographed his front legs and didn't find anything too alarming and are currently working him lightly. You are welcome to come evaluate him for yourself or have your vet evaluate him.
I know they are not very good pictures of him but this is all that are posted. I just want him to ride around nothing to major like high level.
Thanks for your help