Loss of use of a hand or a foot, for the purpose of special monthly compensation, will be held to exist when no effective function remains other than that which would be equally well served by an amputation stump at the site of election below elbow or knee with use of a suitable prosthetic appliance. The determination will be made on the basis of the actual remaining function of the hand or foot, whether the acts of grasping, manipulation, etc., in the case of the hand, or of balance and propulsion, etc., in the case of the foot, could be accomplished equally well by an amputation stump with prosthesis.
38 C.F.R. §4.63