I am sorry for your husband's problem. He must be having really hard time.
Your question is very specific - you are looking for a specific doctor and/or hospital for a specific problem. You might have difficulty to find a doctor this way. Just imagine: in order to give a specific name of a person or a hospital, an advisor/expert/doctor at this website should be the one working in the USA and at least in close proximity to the field of microsurgery
I will open you a little secret: a good specialist in one field/specialty of medicine would only work with another good specialist in another field (e.g. a good surgeon would only work with a good cardiologist or gynecologist, etc.). In other words, good specialists try to maintain a certain circle in order to keep their reputation at a high level.
So, in my opinion, your first step is to find a good surgeon in your area. For this, you may want to visit one of the websites that deals with rating of doctors or hospitals (e.g. RateMD.com). Review the opinions of the people there to find your way. Then, pay a visit to this surgeon and explain him/her your husband's problem. This surgeon will either take up your husband's problem or will refer you to another specialist who will deal with it.
Hope this helps.