Surgical Care of Partial Hand Amputations
As functioning hands are important to just about everyone, surgeons who deal with partially amputated hands must try to restore some function without the complications of neuroma-formation, contractures of the remaining hand, or infection of the wound created by the amputation.
The doctor must learn to identify how a partially severed hand can still be functional. Muscle strength, coordination and sensation must be taken into account. Sensation means the ability to feel hot and cold, to identify where the hand is being touched and to identify two points of contact as being a single or double touch. These are tests the doctor will do in order to decide how functional the patient’s hand will be after restoration. Object recognition using only the hands and closed eyes is another way the doctor can decide how best to manage the partially severed hand.
Another test of whether or not the hand will have sensation is called the “Wrinkle Test”. In it, the hand is placed in warm water for thirty minutes. Areas of the hand that have lost nerve sensation will not wrinkle after the test is performed.
These injuries happen to small children who get a finger or two caught in a door as well as to men who use various kinds of saws in construction. The treatment is different when a child is involved when compared to how an adult is involved. In adults, an area of defatted skin is pulled over to cover the amputated skin of the fingertip. In children, fatted tissue and skin are used to cover the defect in an attempt to revascularize the area and to maintain function of the fingertip.
The fingertip is divided into several zones, each of which has a slightly different method of surgical healing. Doctors use microsurgical techniques to get blood flow to the injured fingertip and to restore sensation. Sometimes an amputation is necessary if the distal end of the finger has no blood supply. Sometimes a part of the nail bed can be salvaged so that the nail can grow back after the injury, while at other times, the nail bed is completely lost as part of the amputation.
If the nail bed is lost, a nailbed from an existing toe can be grafted onto the tip of the remaining finger so as to yield a more aesthetic appearance. The arteries and veins may need to be reattached using microvascular techniques but it takes time to know whether or not a nerve resection will “take”. Bones involved with a partial finger amputation are fixed with wires that hold the bones in place until it can heal on its own.
In some cases, an important finger or thumb can be replanted back into its original state. This requires the use of microvascular techniques that allow for an improvement in circulation and sensation of the replanted finger or thumb. Some fingers have been salvaged after 30 hours without circulation if they have been kept in cold storage during that time.
Replantation is suggested when multiple fingers have been severed, or when part of the palm or wrist has been severed. Thumbs are especially good candidates for replantation because there are no good artificial ways of restoring thumb function after it has been lost. Even if some of the joints of the fingers or thumb become stiff after replantation, the digit usually does well as long as the connection to the hand bones is intact.
Each digit that can be replanted in a multiple finger loss action has the ability to be replanted with some restoration of the affected digit adding to the overall function of the hand. It is controversial as to whether or not to try and reattach a single digit. Sometimes, even though the digit has been restored, it has such a poor ability to function that it interferes with the normal functioning of the hand and would be better off being amputated. This is true of all digits of the hand with the exception of the thumb which should be reattached if at all possible.
If there are other serious traumatic injuries or significant medical disease present, it is usually wiser to let an amputated finger or fingers to remain that way. If given the okay to replant a finger, the survival rate of the finger is usually good, in the range of 80-90 percent.
The thumb is the most important part of a functional hand and this is why it should be replanted whenever possible. If there is a loss of the distal phalanx (the distal knucklebone) of the thumb, it results in about twenty percent loss of function of the hand itself and complete loss of the thumb results in about 40 percent of the disability of the hand.
If just the distal phalanx of the thumb is affected, it is not as great a loss and the thumb will be able to function without it, especially if the distal part of the thumb is severely crushed or contaminated with bacteria. If the whole thumb must be sacrificed, a toe can be reattached to be part of a new thumb or the first web space between the index and middle finger can be widened so that the person can get by with the index finger acting as the thumb. In some cases, a free finger can be attached to the metacarpal of the residual thumb, providing a thumb-like structure created out of a different finger.
While less serious than thumb amputations, attempts can be made to reattach lost fingers. If this is not possible, the doctor tries to retain as much of the joints and bone left over in order to prepare for a shortened but somewhat functional finger.
In children, reattachment of a missing finger or thumb should always be attempted. The circulation of the child’s hand is good enough to allow for reattachment of the amputated part using microsurgery. As in adults, the outcome is better if the finger has been completely severed off as opposed to suffering a crush injury to the finger. Toe transfers to the thumb area have been found to be successful in children and in adults.
If the fingers cannot be salvaged, the doctor must prepare the hand so that a prosthetic device can be attached. Hand reconstruction varies with the type of amputation involved. For example, if just a thumb is remaining, attaching a toe could lead to reasonable function of the reconstructed hand. Prosthetic devices can be attached to add functionality of the hand.
The biggest complication after a partial hand loss is pain. What’s true is that the more motivated patient who is better able to accept their deformity have less pain-related disability when compared to a less motivated patient.
Nail deformities are also problems affecting severed fingers. If the nail is severely deformed, the best choice may be to remove any leftover nail matrix so that no nail will grow there at all.
The amputated hand can also be complicated by the development of a neuroma in the residual hand. These can be removed, allowing for less pain. Contractures of the hand are also possible and are treated by releasing the affected tendons. Sometimes the entire hand gets contracted, requiring more than one release.
There is often cold intolerance after a hand has been replanted but it usually gets better over time. If the blood flow to the hand is at least partially obstructed, the hand may continue to be painful with use on a more permanent basis. In such cases, the hand is usually nonfunctional and is prone to repeated trauma. If this is the case, a more proximal amputation of the hand may need to be attempted.