You can hope it is pana, which dogs out grow. They can also have elbow dysplasia. Aside from working with the vet, the best thing is to keep him lean. See
http://www.puppychow.com/products/po...condition.aspx Adjust his food as needed. If you have him on a small breed puppy chow, you might switch to the adult version. Puppy chows tend to be formulated for fast growth, sometimes too fast for the developing joints. Don't give him any supplements unless the vet says so. Avoid giving him much except his dog chow.
My 13 year old Lab, Aster had a limp in her riht front leg at 4 months. My vet put her on an anti-inflammitory. By a year, she easily passed her X-rays and worked until she was 10 as a dog guide.