Microsurgery

Microsurgery is a surgical technique that concentrates on the repair of small blood vessels to restore blood flow and nerves to restore sensation.  It allows surgeons to repair damage to partially or fully severed limbs and digits that, in the past, would have required amputation.  It is almost always used in neurosurgery.  However, it is far more time consuming and requires the patient to be kept under anesthetic for a substantially longer period of time.  
During microsurgery, the surgeon uses a microscope and ultra-fine needles and sutures to repair damage.  The techniques were first developed in the 1920s in Denmark to expand the range of surgical options for repair of the vocal cords and throat.  From there it spread to surgery of the inner ear and by the 1960s, it was being used to repair blood vessels as small as 1mm in diameter.  
In 5 to 9, Robert Chase has to justify his use of microsurgery to restore a severed thumb.
Microsurgery at Wikipedia
Category:Medical procedures