Not knowing the case, symptoms or test results, I would have to assume that there was something they saw that caused them to place the stint in the leg. Could be that your friend has more than one thing going on. There are tests for gout and there could be other causes for the pain your friend is experiencing.
I would suggest your friend ask for tests, lab work, x-rays and a MRI if necessary (I really hate them) to see what could be causing the pain. Maintaining a log of the pain, what kind of pain it is, where it aches, how long it lasts, how it affects him, etc and any other symptoms he has may help the doctor diagnose the problem.
"Could be that your friend has more than one thing going on."
Yes, I suppose he could have an additional problem. I will give him the information you suggested and thank you very much. MrMcCavity