I'm so sorry to hear of your dog's difficulties.  Having a hip 'break down' in a rear leg tripod is a huge deal, and a terrifying prospect for most of us.

Unfortunately, a brace such as you describe would almost certainly cause more problems than it solved.  It would force his muscles to work in a completely different way, and some would be severely restricted by the restraints.  It would in fact restrict the front legs to the point of unbalancing him, if it were firm enough to have any kind of supporting role at the back, and he might even end up falling a lot.   In any case, in my opinion (not a vet, just someone who used to work for vets in a nursing capacity many years ago) it would likely cause him a lot of additional pain and discomfort. 

The only thing I know of which has a chance of helping him is the exciting new procedure where abdominal fat cells are harvested from your own dog and cultured, and the stem cells separated and then injected back into his joint where they trigger the growth of new cartilage.  Even so ... with the hip not in the socket, I doubt it will solve his problems and you might find that, realistically, a cart is really your only option to give him a good quality of life.

As Jerry says, your best bet is to get a specialist consult for him at a referral centre where they will know of all the latest techniques, procedures and equipment which might benefit him. 

I wish you the very best of luck in finding a way to help him!

govtgirl60 said
Yes he is on pain pills, yes the vet saw him and x-rayed him and did not have anything good to say, pics and a video are going to be sent to a group that makes supports to see what they say, he is a 65 pound choco lab mix, 13 years old. He is ok with it for now, dealing with it going out off and on. Still eats ok, rolls on his back in the snow or dirt, barks at the mailman, begs for food at table so those are all good signs.

A support for the back leg attached to a harness would not impact his front legs at all. It is an unusual request it appears, funny I would have thought a typical one, most groups are curious about it, one is excited as it would be new for them. I'll continue to play with it.

Sorry, I was confused because you did mention the straps going around his front legs in the first post. My mental image was clearly not the same as yours!

Nevertheless, I still think that a support might chafe and cause some trouble, because the hip has to be able to move in order for him to walk, and the harness would have to be firm in order to do any good.  If he were mine, I'd be thinking about the cart option as IMHO it would be easier on him and give his hip the rest it needs.  I also like the hip replacement option, though it would be hard work for you and for him.  Good luck finding a solution!