I would not recommend surgery unless it was a last resort. I would recommend looking into some dietary supplements that could help. Since I started giving glucosamine to my 12 years old girl I see a big improvement in her mobility. Here is a website with a little information:
Dog Arthitis Medication - Arthritis Medicine for Dogs
Proper diet, antioxidants and other supplements may really help him a lot.
If you google these words 'dog arthritis natural remedy' you will find more information.