It was the same with me. I did fine with injuries and blood and doctors, etc., until my son needed surgery at a young tender age. I got through the several surgeries, and after that time passed I found that I couldn't bear it so well in later years. If there's an emergency, I guess I could get through it, but I don't like the sight of blood and feel faint in certain situations.
I'll certainly pray about your son's hand. I hope it won't affect his work. My husband was right handed, and when his accident affected the use of his right hand, he had employment difficulties. Please encourage his wife to encourage him to do his hand rehabilitation exercises...