You may want to go on the orthodog Yahoo group to get a lot more info and speak to people who had it done. They are a good resource.
I know of a dog on another forum who had it an APBT as well as one of my friend's Lab, plus have seen dogs doing swim therapy who have had it done. They all seemed to have handled it well, but it does take some time for them to build the muscle and strength back up. It seems they are all up and around quickly. That is from what I've seen.
Patch O' Pits Home to Greatly Loved Ch GRCH, Therapy, and Agility APBTs
My Maltipoo had the FHO surgery in January. She was diagnosed with Legg-Perthes Disease which happens when not enough blood reaches the top of the femur causing the tissue at the top of the femoral bone to die. At home, we performed physical therapy exercises on her leg for about 2 months as directed by the rehabilitative vet we saw when her staples were removed 10 days following surgery. It takes a while for the muscle to build back up again. Today, 6 months later, she is happy and runs like a flash....The only remaining clue that there was any problem at all is that she still occasionally will hold up that back leg, especially when walking on grass or sometimes when she runs. Please let me know what additional info I can provide you.