A surgical instrument includes an end effector having a clevis and first and second jaws mutually rotatable between open and closed positions. The method is based on the iontophoretic application of different concentrations of the natural mediators noradrenaline and acetylcholine, and on the visual or instrumental assessment, based on color or conductivity measurement, of the concentrations causing vasoconstriction, and respectively, vasodilatation of the cutaneous vessels. The support brackets are bonded to the pontoon by adhesive deposits. The stop bolts and associated threaded apertures are designed for minimum overhang of the stop bolts to provide more support.