The decision to have a limb amputated is difficult for the person and his or her doctor. Many times, extensive measures have been tried to save the limb. The major causes of amputation are diabetes and/or peripheral arterial disease that results in either painful, poor limb function or gangrene.
In general, amputation is recommended for:
- Gangrene with or without infection.
- Unbearable pain when at rest.
- Nonhealing, untreatable ulcers.
Tobacco use may be the most important factor in progressing to amputation.
In doing the amputation, the surgeon seeks to remove all dead or dying tissue. Goals of amputation are to relieve pain, encourage wound healing, and increase a person's ability to carry out his or her daily activities.
Amputations and bypass grafting surgery may be planned at the same time to achieve the best results. For example, a person who has gangrene may have an amputation of part of the foot or leg while also having bypass grafting in an attempt to preserve still-living tissue. In a person who is not a candidate for revascularization or who has not had success with previous bypass grafting attempts, amputation alone may be recommended for severe pain at rest, nonhealing ulcers, and/or gangrene.
Preoperative issues in amputations
People with major medical problems, such as diabetes or heart, lung, or kidney problems must be carefully assessed and their medical care optimized before the operation. The importance of the preoperative evaluation cannot be overemphasized. People who have amputations are often chronically or seriously ill. And their risk of dying around the time of the operation as well as in the following years is higher than for other people of the same age.
The appropriate amputation level depends on a number of factors, including why the amputation is needed, the general health of the person, the possibility for recovery and rehabilitation (rehab), and the probability of adequate wound healing. The aim of an amputation is to remove all dead and dying tissue while creating the most useful limb for recovery and rehab. It is very important to make sure that an artificial limb, if desired, can be appropriately fitted.
A below-the-knee amputation is usually preferable. It provides better mobility. Even if a person is very unlikely to be able to walk because of their general health or other medical conditions, a below-the-knee amputation provides for easier transfers and movement while in bed. Walking on an above-the-knee prosthesis (artificial limb) requires a lot more energy than walking on a below-the-knee prosthesis, although young, relatively healthy people manage much better than older, more frail people do. But when a below-the-knee amputation cannot be done, an above-the-knee amputation has the advantage of easier healing.
Sometimes a bypass grafting operation may be done to allow a below-knee amputation site to heal adequately. The most important thing in deciding whether a below-knee amputation will heal is the clinical judgment of a knowledgeable surgeon.
Timing of surgery
In general, amputations for sudden ischemia (when a clot develops and completely blocks blood supply to an extremity) are done to control pain soon after the preoperative evaluation is finished, if possible.
Bypass surgery or angioplasty is always done when possible. Amputation is the last option.
Noninfected gangrene of the fingers and toes can be treated by amputation or can be allowed to "autoamputate" (tissue dies and sloughs off on its own) over a period of time, usually months. Gangrene of other extremities requires amputation.
Infected gangrene should be treated with the goal of getting rid of the infection yet preserving as much of the extremity as possible. Dead or dying infected tissue should be removed (debridement) as quickly as possible. Tissue that is infected but may likely heal should be left. And the person should receive intravenous antibiotics.
If a person is not stable or does not respond to antibiotic treatment and debridement, amputation must be done rapidly. A first emergency amputation is often done with the goal of stabilizing the person. And a second elective operation may be done to remove any further dead tissue and to improve the function of the remaining limb.