Micro-cutting principle using nanotechnology. According to official website of Peking Union Medical College Hospital, trephine scar excision is equivalent to many laser operations. The principle of this operation is mainly to use nano-traceless trephine for micro-resection, and to cut the tissue to the subcutaneous fat layer by using instruments with a diameter equal to or greater than the scar, so as to remove the hypertrophic scar. The operation has a wide range of applications, and is suitable for keloid, cesarean scar, hyperplastic scar and scald scar.