Sorry about the diagnosis. My shih tzu Hobbs was diagnosed with a luxating ulna when I had him for about three weeks. Anyhow I was in the same situation but he did need the surgery. We had the surgery and afterwards the ortho recommended some glocausamine (sp?) to be added to his diet afterwards. They give that to strenghten them up. It's also given to animals with arthritis. Ask if they recommend it for him. I used to buy it at
www.JeffersPets.com for much cheaper than the pet stores or speciality stores. It's just a powder that is sprinkled on their food.
Good luck!