Composite Tissue Allotransplantation helps amputees grab life by the horns
Since the first fully successful procedure was performed in 1999, Composite Tissue Allotransplantation (CTA) has helped many hand amputees enjoy a greatly improved quality of life. On April 12, 1999, Matthew Scott used his new left hand to throw the ceremonial first pitch at the Philadelphia Phillies opening day baseball game. Later in the year he returned to work and went on to enjoy a normal life.
To understand how CTA works, one first must understand the inner workings of the human hand. It weighs less than 2.2 kgs and consists of multiple, intricately structured tissues including skin, fat, 28 muscles, nerves which include 3 primary nerves, blood vessels including 2 main arteries along with tendons and soft tissue.
The skeletal structure of the hand is composed of bones divided into three groups: the carpus, the metacarpal bones, and the phalanges. The muscular system of the hand is composed of extrinsic muscles, which move the whole hand and intrinsic muscles, which cause individual parts of the hand to move. The 3 primary nerves are the median, ulnar, and radial nerves. All three nerves are required to control the wrist, finger and thumb. The 2 main arteries, radial and ulnar, ensure proper blood circulation within the hand.
Hand transplantation differs significantly from organ transplantation, in that it involves so many varying tissues, and has more psychological implications for the patient since it both visible and has so much potential to restore lost abilities. However, like organ transplants, immunosuppresive drugs must still be administered to the recipient in order to prevent the body from rejecting the newly transplanted hand.
The procedure, which can include arms when required, is specifically for patients who have lost hands or forearms due to physical trauma or radical medical interventions. Currently, it is not being considered for birth defects, cancer related amputations, replacement of lost legs and feet or patients whose amputations are limited to fingers. The recipient is required to be in good health and is required to undergo extensive medical testing including but not limited to radiology, blood tests, limb measurements and psychological evaluation, in addition to consultations with multiple surgeons and specialists. Recipients can expect to spend several months in physical therapy after receiving their new limbs.
Unfortunately, even when the surgery itself is a success, patients sometimes experience health problems associated with the immunosuppressive drugs that they are required to take indefinitely. Side effects of the drugs can include, but are not necessarily limited to: Hypertension, acne, tremors, gastrointestinal problems, compromised immunity, increased risk of certain cancers, hirsutism, weight gain, renal and hepatic dysfunction and diabetes. Major lifestyle changes are required after surgery, and due to the problem of decreased immunity associated with these drugs patients must avoid contracting any type of infection, especially within the first 6 months after surgery. They must avoid crowds and people infected with contagious illnesses, and should wear masks while outside. They cannot clean litter boxes, manage houseplants or gardening, and cannot swim in freshwater.
Like internal organs, donated limbs are harvested from brain dead, living donors. Limb transplantation is a long and tedious surgery that can last 12-16 hours, the duration of which is longer than the time it takes to transplant internal organs. Physicians, however, often find hand transplant surgery easier to perform than the reattachment of a severely damaged hand that often consists of crushed bone and torn cartilage. The limb transplantation procedure is performed in a specific order wherein bones are set first, followed by the connecting of tendons, arteries, nerves and finally veins. Possible post-operative complications can involve rejection of the new hand, infection of the surgical site and circulatory blockage.