Microsurgery

# Overview
Microsurgery is a general term for surgery requiring an operating microscope.  The most obvious developments have been procedures developed to allow anastomosis of successively smaller blood vessels and nerves (typically 1 mm in diameter) which have allowed transfer of tissue from one part of the body to another and re-attachment of severed parts. Although microsurgery is used mostly by plastic surgery, microsurgical techniques are utilized by all specialties today, especially those involved in reconstructive surgery such as: General surgery, orthopedic surgery, gynecological surgery, otolaryngology, Maxillofacial surgery, and pediatric surgery.

# History
The advances in the techniques and technology that popularized microsurgery began in the early 1960s. The first microvascular surgery, using a microscope to aid in the repair of blood vessels, was described by vascular surgeon, Jules Jacobson, of the University of Vermont in 1960. Using an operating microscope, he performed coupling of vessels as small as 1.4 mm and coined the term "microsurgery."  Hand surgeons Kleinert and Kasdan performed the first revascularization of a partial digital amputation in 1963.
Nakayama, a Japanese cardiothoracic surgeon, reported  the first true series of microsurgical free-tissue transfers using vascularized intestinal segments to the neck for esophageal reconstruction after cancer resections using 3-4mm vessels. 
Contemporary reconstructive microsurgery was introduced by an American plastic surgeon, Dr. Harry J. Buncke. In  1964, Buncke reported a rabbit ear replantation, famously using a garage as a lab/operating theatre and home-made instruments.
This was the first report of successfully using blood vessels 1 millimeter in size. In 1966, Buncke used microsurgery to transplant a primate's great toe to its hand.
During the late sixties and early 1970s, plastic surgeons ushered in many new microsurgical innovations that were previously unimaginable. The first human  microsurgical transplantation of the great toe (big toe) to thumb was performed in April 1968 by Mr. John Cobbett, in England.  In Australia work by Dr. Ian Taylor   saw new techniques developed to reconstruct head and neck cancer defects with living bone from the hip or the fibula.
Although primarily developed and used by plastic surgeons, a number of surgical specialties now use microsurgical techniques.  Otolaryngologists (ear, nose, and throat doctors) perform microsurgery on structures of the inner ear or the vocal cords. Maxillofacial surgeons and Otolaryngologists use microsurgical techniques when reconstructing head and neck cancer patients.  Cataract surgery, corneal transplants, and treatment of conditions like glaucoma are performed by ophthalmologists. Urologists and gynecologists can frequently now reverse vasectomies and tubal ligations to restore fertility.

# Free tissue transfer
Free tissue transfer is a surgical reconstructive procedure using microsurgery.  A region of "donor" tissue is selected that can be isolated on a feeding artery and vein; this tissue is usually a composite of several tissue types (e.g., skin, muscle, fat, bone).  Common donor regions include the rectus abdominis muscle, latissimus dorsi muscle, fibula, and radial forearm bone and skin lateral arm skin.  The composite tissue is transferred (moved as a free flap of tissue) to the region on the patient requiring reconstruction (e.g., mandible after oral cancer resection, breast after cancer resection, traumatic tissue loss, congenital tissue absence).  The vessels that supply the free flap are anastomosed with microsurgery to matching vessels (artery and vein) in the reconstructive site.  The procedure was first done in the early 1970s and has become a popular "one-stage" (single operation) procedure for many surgical reconstructive applications.
- Traumatic foot/ankle soft tissue wound from motor vehicle accident
Traumatic foot/ankle soft tissue wound from motor vehicle accident
- Anterio-lateral thigh flap free-tissue transfer reconstruction
Anterio-lateral thigh flap free-tissue transfer reconstruction

# Replantation
Replantation is the reattachment of a completely detached body part.  Fingers and thumbs are the commonest but the ear, scalp, nose, arm and penis have all been replanted.  Generally replantation involves restoring blood flow through arteries and veins, restoring the bony skeleton and connecting tendons and nerves as required.
Initially, when the techniques were developed to make replantation possible, success was defined in terms of a survival of the amputated part alone. However, as more experience was gained in this field, surgeons specializing in replantation began to understand that survival of the amputated piece was not enough to ensure success of the replant. In this way, functional demands of the amputated specimen became paramount in guiding which amputated pieces should and should not be replanted. Additional concerns about the patients ability to tolerate the long rehabilitation process that is necessary after replantation both on physical and psychological levels also became important. So, when fingers are amputated, for instance, a replantation surgeon must seriously consider the contribution of the finger to the overall function of the hand. In this way, every attempt will be made to salvage an amputated thumb, since a great deal of hand function is dependent on the thumb, while an index finger or small finger may not be replanted, depending on the individual needs of the patient and the ability of the patient to tolerate a long surgery and a long course of rehabilitation.
However, if an amputated specimen is not able to be replanted to its original location entirely, this does not mean that the specimen is unreplantable. In fact, replantation surgeons have learned that only a piece or a portion may be necessary to obtain a functional result, or especially in the case of multply amputated fingers, a finger or fingers may be transposed to a more useful location to obtain a more functional result. This concept is called "spare parts" surgery.

# Transplantation
Microsurgical techniques have played a crucial role in the development of transplantation immunological research because it allowed the use of rodents models, which are more appropriate for transplantation research (there are more reagents, monoclonal antibodies, knockout animals, and other immunological tool for mice and rats than other species). Before it was introduced, transplant immunology was studied in rodents using the skin transplantation model, which is limited by the fact it is not vascularized. Thus, microsurgery represents the link between surgery and transplant immunological research. 
The first microsurgical experiments (porto-caval anastomosis in the rat) were performed by Dr. Sun Lee (pioneer of microsurgery) at the University of Pittsburgh in 1958. After a short time, many models of organ tranplants in rat and mice have been established. Today, virtually every rat or mouse organ can be transplanted with relative high success rate.
Microsurgery was also important to develop new techniques of transplantation, that would be later performed in humans. In addition, it allows reconstruction of small arteries in clinical organ transplantation (e.g. accessory arteries in cadaver liver transplantation, polar arteries in renal transplantation and in living liver donor transplantation).

# Links
E-Medicine Microsurgery Principles
Microsurgeon.org History of Microsurgery