Investigators hypothesize that nerve regeneration in the nerves in the arm and digital nerve in the hand can be significantly enhanced when they are combined with post-surgical electrical stimulation. Furthermore, the improved nerve regeneration with post-operative electrical stimulation will result in a significant improvement in hand functions compared with surgery alone.To test these hypotheses, the objectives of this study are to: 1) quantify the functional and physiological consequence of severe nerve injury in the arm, and 2) to compare the outcome of conventional nerve surgery alone versus nerve surgery followed by post-operative electrical stimulation.