
I know of a dog who dislocated it's hi at age 10 by falling fom a first floor balcony that wasn't yet fenced in. After trying to reloae it several times the vet cut the head of the femur of.
A year later the dog is running around as if it didn't have athing wrong with it, with that leg held in place by muscle alone.
I can't remember what the procedure is called, but is somethign worth considering if pain is an issue.
Good muscle is what will help with this problem so I would suggest if you can fit in another 10 minute walk or even two this will build him up nicely. I would imagine that after that the walks could be lenghtened, but seek your speciall8sts advice.
This was the advice of a specilist giving a talk on HD who had a severely dysplastic labrador, who he worked lightly despite her problem.