Anastomosis is the procedure in which arteries, veins, ligaments, blood vessels, and nerves are reattached in an operation such as a toe to thumb transplant. For instance, in the operation, arteries in the thumb are attached to arteries in the toe. The arteries are then sutured together using a microscope and thread finer than human hair.1
Operations like these are performed when a hand or fingers have been amputated or severed and cannot be reattached or saved. In a toe to hand transplant, a physician removes a patient's big toe and attaches it in place of the missing thumb. (Opposable thumbs are necessary to grasp and pick up objects.) While big toes are not nearly the same size as thumbs, they function in similar ways. Structurally, comparable nerve
locations in the thumb and toe make nerve regeneration possible.
In hand transplants, donors must have total and irreversible damage to the brain
and a consenting family. Then they are mandatorily screened for blood type and hand size. Other factors such as gender, skin tone, and age are preferences of the individual and non-mandatory. While a hand transplant operation is difficult, the operation is sometimes easier than a replantation of a hand that is mangled or damaged.2
Post-operation complications with hand and toe to thumb transplants are rejection, blockage of the
blood supply, and infections. In these cases, fingernails fall off while the hand rots and re-amputation may be necessary. The development of immunosuppresive drugs help prevent these life-threatening situations.
1Toe to Thumb Transplant, Gary Wickert, July 2000,
http://www.gmtoday.com/features/health/healthstory58.asp
2Pioneers in Medical Innovation,
http://www.handtransplant.org/