Lower-Extremity Amputations

Updated: Apr 04, 2016
  • Author: Janos P Ertl, MD; Chief Editor: Vinod K Panchbhavi, MD, FACS  more...
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Overview

Background

Lower-extremity amputation is one of the oldest known surgically performed procedures, dating back to prehistoric times. [1, 2]  Neolithic humans are known to have survived traumatic, ritualistic, and punitive rather than therapeutic amputations. Cave-wall hand imprints have been found that demonstrate the loss of digits. Unearthed mummies have been found buried with cosmetic replacements for amputated extremities.

The earliest literature discussing amputation is the Babylonian code of Hammurabi, inscribed on black stone, from 1700 BCE, which can be found in the Louvre. In 385 BCE, Plato's Symposium mentions therapeutic amputation of the hand and the foot. Hippocrates provided the earliest description of therapeutic amputation in De Articularis for vascular gangrene. Hippocrates describes amputation at the edge of the ischemic tissue, with the wound left open to allow healing by secondary intent.

The main risks described in the early history of amputation surgery were hemorrhage, shock, and sepsis. Before the discovery of anesthesia, the procedure itself was quite difficult. The patient would be held down by a number of assistants and be given alcohol (usually rum). The patient would essentially be awake and aware during the procedure.

The original surgical principles as described by Hippocrates remain true today. Refinements of surgical technique (eg, hemostasis, anesthesia, and improved perioperative conditions) have occurred, but only relatively small technical improvements have been made.

In the United States, 30,000-40,000 amputations are performed annually. In 2005, there were an estimated 1.6 million individuals living with the loss of a limb; by 2050, this figure is expected to rise to 3.6 million. [3]

Amputation is still often viewed as a failure of treatment. The responsibility for performing an amputation may even fall on the most junior member of the surgical team. Whatever the reason for performing an extremity amputation, it should not be viewed as a failure of treatment. Amputation can be the treatment of choice for severe trauma, vascular disease, and tumors. Patients and family members must be aware of their options and have realistic expectations of surgical outcomes in order to make informed decisions regarding amputation. [4, 5]

One of the greatest difficulties for a person undergoing amputation surgery is overcoming the psychological stigma that society associates with the loss of a limb. Persons who have undergone amputations are often viewed as incomplete individuals. After the removal of a diseased limb and the application of an appropriate prosthesis, the patient can resume being an active member of society and maintaining an independent lifestyle.

Although a diseased limb can be removed quite readily, resolving the problem of the extremity, the care does not end there. The surgery must be performed well to ensure that the patient is able to wear a prosthesis comfortably. Knee joint salvage enhances rehabilitative efforts and decreases the energy expenditure required for ambulation. [6]

The patient must learn to walk with a prosthesis, apply and remove the prosthesis, care for the prosthesis, monitor the skin and the presence of any pressure points, ambulate on difficult terrain, and use the commode at night. Because of the complexity of these issues, the treatment team should include the surgeon, the primary care physician, a physical therapist, a prosthetist, and a social worker. [7, 8]

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Indications

Amputation is the treatment of choice for diseased limbs and devastating lower-extremity injuries for which attempts at salvage and reconstruction may be lengthy, emotionally and financially costly, and have a less-than-satisfactory result. Lower-extremity amputations may be performed for the following reasons [1, 2] :

  • Peripheral vascular disease (PVD)
  • Tumors
  • Infections
  • Congenital limb deficiency

Whatever the indication for amputation, the goal remains length preservation and surgical reconstruction that maintains the most functional limb possible.

Peripheral vascular disease

The leading indication for limb amputation in the United States is ischemic disease (eg, PVD), [9, 10, 11, 12, 13]  primarily in elderly persons with diabetes mellitus, who often experience peripheral neuropathy that progresses to trophic ulcers and subsequent gangrene and osteomyelitis. Persons with diabetes mellitus account for 50% of the population with PVD. An estimated 65,000 lower-extremity amputations are performed for this group each year. Limb removal for PVD is performed for uncontrollable soft-tissue or bone infection, nonreconstructable disease with persistent tissue loss, or unrelenting rest pain due to muscle ischemia.

Trauma

Although safer equipment exists and improvements in limb salvage surgery have been made, traumatic limb loss continues to occur because of industrial and motor vehicle accidents. These accidents involve high-grade open fractures with associated nerve injury, soft-tissue loss, and ischemia and unreconstructable neurovascular injury. In this setting, limb salvage may initially be successful, only to end in an infected painful extremity that affects the patient's activities of daily living and work. Attempts at limb salvage are often made with less-than-favorable results, leaving the patient with an extremity that is less functional than a prosthesis would be and resulting in workdays lost and expense in treatment.

Severe open (IIIc) fractures with popliteal artery and posterior tibial nerve injuries can be treated with current techniques; however, treatment is at a high cost, and multiple surgeries are required. The result is often a leg that is painful, nonfunctional, and less efficient than a prosthesis. [14]

Tumor

The goal in treating malignant bone tumors is to remove the lesion with the lowest risk of recurrence. With the advent of advanced techniques, limb-salvage surgery has replaced amputation as the primary treatment for bone tumors. To recommend limb salvage, the risk of local recurrence must be equal to that of amputation, and the salvaged limb must be functional.

Infection

Treatment of sepsis with vasoconstrictor agents may at times lead to vessel occlusion and subsequent extremity necrosis, necessitating amputation. At other times, eradication of infection from many difficult sources necessitates removal of the affected digit or limbs.

Congenital limb deficiency

Congenital absence and limb malformations account for a small percentage of amputations. Such amputations are performed primarily in the pediatric population because of failure of partial or complete formation of a portion of the limb. Congenital extremity deficiencies have been classified as longitudinal, transverse, or intercalary. Radial or tibial deficiencies are referred to as preaxial, and ulnar and fibular deficiencies are referred to as postaxial.

These situations are evaluated on an individual basis because these limbs are often functional and amenable to orthotic management or limb reconstruction. When amputation is under consideration, a higher and more functional level than the patient's current level should be obtainable.

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Contraindications

The decision to perform an amputation often comes after all other options have been exhausted. It is a final decision that cannot be reversed once initiated. The only contraindication for amputation is poor health that impairs the patient's ability to tolerate anesthesia and surgery. However, the diseased limb is often at the center of the patient's illness, leading to a compromised medical status. The removal of the diseased limb is necessary to eliminate systemic toxins and save the patient's life.

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Technical Considerations

Anatomic considerations

Knowledge of the regional cross-sectional anatomy of the lower limb is necessary to ligate the vessels and to identify the major nerves for sharp resection.

Procedural planning

Amputation of the lower extremity is often the treatment of choice for an unreconstructable or a functionally unsatisfactory limb. Amputation must be performed with great care and be considered a reconstructive procedure, similar to total hip arthroplasty (internal amputation of the hip joint) or mastectomy (amputation of the breast), rather than an ablative procedure.

The higher the level of a lower-limb amputation (see the image below), the greater the energy expenditure that is required for walking. [6] As the level of the amputation moves proximally, the walking speed of the individual decreases, and oxygen consumption increases.

Image that depicts the various levels of lower-ext Image that depicts the various levels of lower-extremity amputations.

For most people who have undergone transtibial amputations, the energy cost for walking is not much greater than that required for persons who have not undergone amputations. For those who have undergone transfemoral amputations, the energy required is 50-65% greater than that required for those who have not undergone amputations. Additionally, those with PVD who have undergone transfemoral amputations may have cardiopulmonary or systemic disease and require maximal energy for walking, which makes independence difficult to maintain. (See Table 1 below.)

Table 1. Energy Expenditure for Amputation (Open Table in a new window)

Amputation level Energy above baseline, % Speed, m/min Oxygen cost, mL/kg/m
Long transtibial 10 70 0.17
Average transtibial 25 60 0.20
Short transtibial 40 50 0.20
Bilateral transtibial 41 50 0.20
Transfemoral 65 40 0.28
Wheelchair 0-8 70 0.16

Amputation wound healing is a concern because most amputations are performed for compromised circulation (eg, PVD, damaged soft-tissue envelope in trauma). The skin is a very important factor in the ambulatory ability and ultimate outcome for the person who has undergone an amputation. The soft-tissue envelope of the residual limb now becomes the proprioceptive end organ for the interface between the residual extremity and the prosthesis. For effective ambulation, this envelope should consist of a sufficient mass of mobile nonadherent muscle and full-thickness skin and subcutaneous tissue that can accommodate axial and shear stress within the prosthetic socket.

Split-thickness skin grafting is sometimes used to complete wound coverage or decrease tension on the wound closure, while maintaining the limb length. When placed over soft tissue with avoidance of bone scarring, these grafts can function quite well. However, most often these skin-grafted areas do not tolerate the axial and shear stresses within the prosthesis and may require removal at a later date, when the postoperative swelling has subsided.

In the patient with vascular disease, preservation of limb length must be balanced against wound-healing ability and the potential for ambulation. A vascular surgery evaluation should be obtained to determine the feasibility of vascular reconstruction in the hopes of maintaining limb length.

For the patient to effectively transfer weight from the residual limb to the prosthesis, an intact soft-tissue envelope is required, as described above. Load transfer is accomplished through direct means, indirect means, or both. Direct weight transfer implies that the residual limb is capable of end weightbearing within a prosthesis. End weight bearing is easily accomplished through disarticulations at the ankle (Symes-level amputation) and knee levels. The proximal articulation of the joint is maintained, functions normally, and is broad enough to distribute the end-bearing forces.

Although joint amputations maintain length and muscle attachments, patients often have a difficult time with prosthetic fitting. The issues after knee disarticulations include that in which the more-distal center of knee rotation makes sitting in cars and closed areas difficult. The knee protrudes farther than the contralateral knee, and the lower leg is much shorter. For ankle disarticulations, patients report that the prostheses are too bulky.

Indirect weight transfer implies distributing load to a more proximal bony area and incorporating a total-contact interface with the soft tissues of the extremity. In the past, with transdiaphyseal amputations, an indirect weight transfer prosthesis has been used because of the small bone diameter, which is believed to be ineffective in applied load distribution. However, end weightbearing can be accomplished in osteomyoplastic reconstructions in conjunction with a total-contact prosthesis. This reconstruction provides a more durable, pain-free, active, and functional residual extremity. (See Technique.)

Complication prevention

Although the prosthetic industry has made significant advances over the past several decades, pain is still a problem for many patients who have undergone lower-extremity amputations. Prosthetists have been required to correct and relieve these painful and sensitive areas. Often, symptomatic or tolerable improvement is achieved; however, further surgical intervention can be necessary.

Pain in patients who have undergone lower-extremity amputations may originate from bone, muscle, nerve, or skin. These painful symptoms usually lead to significant disability, difficulty with daily activities, and decreased ability to wear the prosthesis.

A careful evaluation to determine the exact source of the pain is necessary. A common pitfall is to perform a simple revision surgery that just shortens the limb. This procedure may be unsuccessful if the reason for the pain has not been discovered and corrected.

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Outcomes

The success of amputation surgery is multifactorial in terms of functional and emotional satisfaction. The goal is to achieve a useful residual limb in an individual who is active with a positive attitude, who accepts the amputation, and who continues to be a productive member of society. [15, 16]  

Most amputations in the United States are performed in elderly persons for PVD. The associated mortality is 20% within the first year and 40% within 5 years. This high mortality creates a difficulty with follow-up and documentation of functional outcome, and studies are minimal and mostly incomplete. Of patients who undergo dysvascular amputations, 15-28% undergo contralateral limb amputations within 3 years. Of elderly persons who undergo amputations, 50% survive the first 3 years.

In a review to assist in patient management, Matsen et al attempted to identify factors that correlate with the perceived amputation result. [7] Residual limb length made no difference to patients' perceptions. Factors that appeared to influence perceptions included the condition of the contralateral limb; comfort of the residual limb; comfort, function, and appearance of the prosthesis; social factors; and the ability to participate in recreational activities. Additional emotional and physical impairment issues were posttraumatic stress disorder, sexual dysfunction, and depression. For the 25-35% of patients who experience depression, appropriate consultation should be obtained.

Kayssi et al performed a retrospective cohort study of 5342 adult patients (68% male, 32% female; mean age, 67±13 years) who underwent lower-extremity amputation in 207 Canadian hospitals from 2006 to 2009. [17]  The most common indication for amputation was diabetic complications (81%), followed by cardiovascular disease (6%) and cancer (3%). In all, 65% of the 5342 patients were discharged to another inpatient or long-term care facility, and 26% were discharged home, with or without extra support. The vast majority of the patients (96%) were diabetic (96%), and nearly two thirds (65%) required a below-knee amputation. Factors predictors of a prolonged hospital stay (>7 days) included the following:

  • Amputation performed by a general surgeon
  • Cardiovascular risk factors, such as diabetes, hypertension, ischemic heart disease, congestive heart failure, or hyperlipidemia
  • Amputation performed in the provinces of Newfoundland and Labrador, New Brunswick, or British Columbia
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