Femoral head osteotomy operation?

[Woodrock]

Just wondered if anyone had any experience of dogs having this op? Our pointer/collie came from a rescue centre and had just had this operation when we got him at 3months old (They think he was hit by a car). He is now 3 and very fit & active. I took him to the vets recently for his annual checkup and the vet mentioned that at his size he was at the limit for a succesful outcome. (He is 20kilo's) I have noticed that he twists his spine slightly when he runs but it does'nt slow him down! Is there anything I can do to prolong his active life, I am just a little concerned that the twisting motion could damage his spine or cause arthritis? He obviously uses the dodgy leg all the time but it does not appear to be as strong as the other one. He is on a joint supp.
Any info gratefully recieved!

 

[Cedars]

Chlo was 22kg and was fine just had to limit herself but she did that not us. Joint supps, good quality food and hydrotherapy was recommended to us.