Wyo,

I have had a finger reattached and I too have lost sensation in the finger, actually four fingers. The secret to a successful recovery for me was good, consistant, and creative Physical Therapy. Consistatncy may be the most vital of the three. Because this injury happend at a knuckle( You didn't say at a joint, which is it?) there may be some trouble with the movement of the finger. If it was severed through the joint I would wonder at its future mobility. Mine finger were cut through the joint at the middle of the middle finger. The others were cut at either side of this median joint. The micro surgeries were very successful but it was the PT that save my ability to play at all. My guess is that I have 40% mobility in my left hand and all of that is due to solid PT. ( I used an Autoharp)

Reassure the young man, there is life after this kind of injury. Even musical life.

Regards

Don