What is amputation?

Indications and Procedures

Amputations are performed in order to preserve life or to avoid more extensive damage or destruction to an individual or a portion of the body. They are performed in response to pathological processes (bacterial or viral infections, ischemia, or cancer, for example) that do not respond to treatment or to address the aftereffects of violent trauma (accidents, crushing injuries, or bullet wounds) in which tissues have been injured so extensively that they cannot be repaired, restored, or otherwise salvaged or saved.

Extremities are the most common sites for amputations, and there are four principal reasons for removing all or part of an extremity. The first is trauma which is so severe that surgical or other repair is not possible. The second reason is the presence of a tumor in the bones, soft tissues, muscles, blood vessels, or nerves of the extremity. A third cause is extensive infection that does not respond to usual or conservative treatment or that may lead to septicemia, a generalized infection that spreads throughout the entire body through the bloodstream. The final indication for performing an amputation is the presence of peripheral vascular
disease, a group of conditions that compromise or reduce the blood supply in an extremity.

Most amputations of the leg are performed because of impaired circulation
, or ischemia. Several conditions may lead to ischemia, the most common of which is inadequately controlled diabetes mellitus. Others include atherosclerosis (a buildup of plaque in a blood vessel that restricts circulation), cellulitis, and vascular diseases. Bacterial infection can also lead to impaired circulation. When circulation continues to be inadequate, gangrene develops; infection can also contribute to or accelerate existing gangrene.

There are three general classes of amputation: provisional or open, conventional or standard, and osteomyoplastic. The techniques for each are briefly described.

The technique for a provisional amputation is often referred to as guillotine. In the past, this approach was commonly used in battle situations where speed was important to minimize both blood loss and subsequent infection. Currently, the technique is used mainly to remove a victim from a dangerous situation, typically one causing a crushing injury in which the alternative to amputation is death. All tissues are cut circularly. Skin is retained to the greatest degree possible, muscle and fascia are cut shorter, and the bone is cut shorter still. The hope is that the soft tissues (skin and muscles) will ultimately cover the bone, but the results are generally unsatisfactory. Large scars are common, and muscle frequently adheres to the bone. Long periods are required for healing, infections are common, and prostheses do not fit well. Another, more definitive amputation is usually required at a later date.

In a conventional amputation, skin, underlying tissues, muscle, and fascia are all cut in curved flaps that originate at the end of the remaining, unamputated bone. The muscles, fascia, bone, and major blood vessels are divided at the base of the remaining bone; nerves are cut at a slightly higher level, approximately 2.5 centimeters (1 inch) above the end of the bone. The nerves will retract somewhat into the muscle, minimizing postoperative pain. Muscles are tapered so that large masses of tissue are not present over the end of the stump; this will enhance the fit of a later prosthesis. At the cut end of the bone, the outer layer of bone is removed in order to reduce the possibility of bone spurs forming at some time in the future. The skin over the amputation site is closed loosely to avoid stretching as it heals.

The purpose of an osteomyoplastic amputation is to improve function after a prosthesis is fitted. The preparation of skin and fascia is the same as for a conventional amputation. Nerves and blood vessels are also divided. Muscles are separated for about 5 centimeters (2 inches) past the point where the bone will be cut. A portion of the outer surface (periosteum) from the bone to be amputated is sutured to the divided muscle. The bone is then cut. The prepared flap of periosteum and muscle is sutured to the periosteum of the stump. This procedure covers the marrow cavity of the stump, helps to preserve the remaining bone, and reduces postoperative infections. The remaining muscles are then sutured across the end of the stump. The skin is closed as in a conventional amputation. In an alternative procedure, holes are drilled in the bone of the stump. Muscles are inserted in the holes and sutured in place. The net effect of these osteomyoplastic procedures is to strengthen the musculature of the stump and to improve mobility for a prosthesis.

There are several common sites or levels for amputations of the leg. Syme’s amputation is performed when most of the foot has been destroyed by trauma or compromised by poor circulation. In this type of amputation, the bones of the foot are removed, and the end of the tibia becomes the weight-bearing surface for the prosthesis.

A below-the-knee (BK) amputation is used to provide additional mobility for a prosthesis. It also leads to more complete rehabilitation because the knee is still available for movement. It is also associated with a reduction in phantom limb pain.

An above-the-knee (AK) amputation is frequently selected when gangrene extends into the muscles or skin of the calf. When the muscles of the leg are contracted, a prosthesis is not likely to be fitted or used; thus there is no advantage to a BK amputation in this situation. The AK amputation is associated with the highest healing rate for amputations among patients with peripheral vascular disease. The rate of a repeat amputation performed at a higher level on the leg is also low. Prostheses that permit walking, however, are less efficient with amputations at this level.

Both amputations have about the same rate of healing, but a higher percentage of individuals with BK amputations walk on prostheses than do those with AK amputations. The choice between BK and AK amputation is determined by the general health of the patient and the potential for rehabilitation. The most important determinant of level of amputation, however, is the vascular status of the patient.

The leg can also be amputated at either the knee or the hip; such a procedure is a disarticulation, an amputation through a joint. A knee disarticulation is most commonly used with children to preserve the growing portion (epiphysis) of the remaining thigh bone. A hip disarticulation is used with tumors or extensive soft tissue injuries in the thigh. Special prostheses that permit walking after such procedures are available but are relatively uncommon; however, as technology improves, such prostheses are becoming more widely available and increasingly comfortable and functional.

Portions of the upper extremity are usually amputated after extensive trauma. Malignant disease of the bone or muscle is a less common reason for amputation at these sites. The considerations described for the lower extremity are applicable for the upper extremity, namely, preserving as much tissue as possible for later rehabilitation and recovery of function. The sites for amputation are also analogous. Individual fingers can be amputated, or the entire hand can be amputated at the wrist (a location similar to the Syme’s amputation of the foot). Similarly, the forearm can be amputated either below the elbow or above the elbow. Portions of the arm can be disarticulated at the elbow or at the shoulder. Restoration of function is far more difficult, however, in an upper extremity amputation than for a lower extremity amputation. It is easier to restore the ability to walk than it is to restore hand function.

Uses and Complications

The level or site of an amputation is critical to recovery and rehabilitation. When an amputation is performed because of cancer or some other malignant disease, the principal concern is a wide excision of any apparent tumor. When amputation is performed after the patient has sustained significant trauma or to treat peripheral vascular disease, the major factor determining the best site is usually the extent of healthy tissue. Other important factors include preserving sufficient length in the remaining bone or stump so that a prosthesis may be used. Furthermore, the prosthesis must be functional, must have adequate space for attachment, and must be cosmetically acceptable. The scar must be placed so that it will not break down from mechanical traction or interfere with the fit of the prosthesis.

In general, the more bone that can be left in place, the more functional a prosthetic limb will be; patients will also have better control of their prostheses. Frequently, special procedures will have to be used to save skin or to graft skin to the site of an amputation so as to preserve the length of the bone. The issue of bone length is especially critical in amputations of the upper extremities, as arms, hands, and fingers are so important in daily functions. The prospects for rehabilitation are also considered when an amputation is contemplated. For example, there is less need to preserve bone for a prosthesis if an individual is not inclined—because of temperament, age, or physical condition—to rehabilitate a lost body part.

There are different regional considerations for patients requiring an amputation for peripheral vascular disease. The ability of the skin and other tissues to heal is directly dependent on an adequate supply of blood. Injections of dye into local small arteries, a procedure called arteriography, are used to determine if the vessels can deliver sufficient blood to a proposed amputation site or around joints such as the knee.

Amputations for extensive trauma should be performed soon after the injury is sustained in order to reduce the chances for contamination or infection. This practice will also assist in subsequent psychological adjustment to the loss of the body part.

Bedridden patients frequently suffer from ulcers of the skin, or bedsores, lesions that do not heal well if at all. In combination with impaired circulation (ischemia), these ulcers can lead to the need for amputations. This group of patients must be carefully prepared for surgery by conditioning muscles that will remain after the amputation. Before an amputation is attempted, extensive efforts must be made to heal all skin ulcers. Physical therapy is frequently used before the surgery to strengthen and improve the tone of muscles. Antibiotics and frequently changed dressings are employed to fight infection. Patients should be moved frequently to avoid the formation of new skin ulcers. Special beds are often used to avoid concentrating pressure on body parts; this can be accomplished with pillows and lambskin mats. In some cases, ice packs are used in the days immediately prior to amputation to limit the spread of infection and to reduce pain.

Conventional postoperative care for amputation focuses on providing optimal tissue care: movement and specific exercises to prevent contractures (the loss of use for muscles), the compression of tissue to prevent edema, and the initiation of physical therapy to regain or retain the optimum use of the remaining body part. The ultimate goal is to provide a prosthesis wherever possible and appropriate in order to improve the patient’s quality of life and vocational opportunities.

Edema is minimized by applying tight dressings to the amputation site. After sutures are removed, elastic bandages are used for the next several weeks. Exercises and movement of the stump will prevent contractures. These exercises should be started as soon as possible after the amputation. When a portion of an arm or leg has been removed, it is important to move and stretch the entire limb.

One problem associated with amputations is called phantom limb pain: the perception of pain in a body part that is no longer attached to the body. Typically, a patient who has lost a limb will experience pain or other sensation as if the limb were still intact. This phenomenon occurs because of stimulation in the nerve endings of the remaining stump. Such sensations are amplified in the posterior horn, a portion of the spinal cord. The nervous impulses are processed by the brain and interpreted as pain; it is this subjective feeling that the patient experiences. Phantom limb pain can usually be prevented by surgical techniques employed at the time of amputation.

Traumatically amputated body parts can sometimes be reattached. Portions of fingers, hands, and entire upper extremities have been successfully reattached; lower extremity reattachments are less common. The regeneration of nerves, however, is not uniformly accomplished. The myelin sheaths of nerves—the cells that surround many nerves to provide insulation and to increase the velocity of nerve impulse conduction—must be approximated for successful regeneration. The lack of nerve regeneration can affect either motor or sensory aspects of the body part. Lack of motor nerve regeneration leads to disuse atrophy and loss of functional use of the body part. Cosmetically, the body usually appears normal. Loss of sensory innervation requires adaptation, but the ability to move the body part is not affected. If the sensory loss is from skin only, the deficit is usually not significant. Sensory loss in fingers and toes is more serious; other senses such as sight and position receptors in joints must be relied upon to compensate for the lack of direct input from fingers or toes. These deficits can be overcome with rehabilitation.

Amputations performed by surgeons skilled in techniques appropriate for ischemic or necrotic tissue have the lowest incidence of postoperative complications and the highest degree of success for subsequent rehabilitation. The death rate for amputations required for isolated trauma, infection, or tumors is less than 3 percent. In contrast, amputations related to vascular diseases result in death for approximately one patient in four. Mortality rates rise with the removal of increasing amounts of a body part: The removal of a toe or foot is less likely to end in death than the removal of an entire leg.

Perspective and Prospects

Historically, techniques for amputation evolved on the battlefield. Amputation was the only treatment available for battle casualties; the alternative was death. Military surgeons were known for speed. In the early part of the twentieth century, antibiotics were discovered. Improved instrumentation and operative techniques were first developed in the 1950s. Microscopic procedures have been perfected more recently. The net effect of these developments has been to reduce the need for amputation following trauma. These same techniques have enabled the reattachment or reimplantation of fingers or other extremities.

When amputation is necessary, however, the surgeon must weigh the desires of the patient against his or her best interests. It is natural for patients to want to retain as much original tissue as possible, but surgeons prefer to perform an amputation only once. Impaired circulation compromises tissues. When individuals with conditions such as diabetes require amputation and insufficient tissue is removed, the result is frequently another amputation. Individuals with poorly controlled diabetes may lose their entire legs in a series of amputations.

After an amputation, physical therapy begins the rehabilitation process. As soon as the patient can tolerate movement, exercises are undertaken. The goal of these activities is to return the person to as normal a level of function as possible. The services of an occupational therapist are used to regain old motor skills or to learn new ones. An artificial body part is fitted by a prosthetist. The sooner a prosthesis is fitted, the greater is the probability that the patient will adapt successfully to it. Temporary prostheses initially fitted within the first twenty-four hours following surgery have had high degrees of acceptance.

Prostheses typically are of two varieties: functional and cosmetically appealing. Prostheses with wires attached to movable hooks allow limited motor function of hands. Muscles of the forearm are retrained to provide movement of the hook. Lower limb prostheses are usually more anatomically correct and cosmetically appealing. They allow walking and other movements but do not usually allow fine motor control of toes. This does not preclude the adaptation and eventual recovery of fairly complex motor skills, including those required for participation in sports activities. Research is ongoing to test the viability of implantable brain-computer interfaces that would enable patients to control their prosthetic limbs with thoughts; however, at present, these devices pose a high risk of infection and remain in the experimental stage.

One predictor of eventual success with the prosthesis is the age at which it is fitted. Young children adapt rapidly, but the older the patient is, the more difficult adaptation to a prosthesis becomes. Older persons often merely tolerate an artificial limb while younger persons accept the prosthesis and continue with the activities of their lives. Much of the rehabilitation after an amputation is psychological. With appropriate support and therapy, the potential for a nearly normal life exists for most persons experiencing an amputation.

Bibliography

Barnes, Robert W. Amputations: An Illustrated Manual. Philadelphia: Hanley & Belfus, 2000.

Brunicardi, F. Charles, et al., eds. Schwartz’s Principles of Surgery. 9th ed. New York: McGraw-Hill, 2010.

Kellicker, Patricia Griffin. "Amputation—General Overview." Health Library, December 30, 2012.

May, Bella J. Amputations and Prosthetics: A Case Study Approach. 2d ed. Philadelphia: F. A. Davis, 2002.

Smith, Douglas G. “General Principles of Amputation Surgery.” In Atlas of Amputations and Limb Deficiencies: Surgical, Prosthetic, and Rehabilitation Principles, edited by Smith, John W. Michael, and John H. Bowker. 3d ed. Rosemont, Ill.: American Academy of Orthopaedic Surgeons, 2004.

Townsend, Courtney M., Jr., et al., eds. Sabiston Textbook of Surgery. 19th ed. Philadelphia: Saunders/Elsevier, 2012.