Lower-Extremity Amputations

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 mentioned therapeutic amputation of the hand and the foot. Hippocrates' On the Articulations provided the earliest description of therapeutic amputation for vascular gangrene. Hippocrates described 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]

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

• Peripheral vascular disease (PVD)
• Trauma
• 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, 14]  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.

In a study analyzing the relation between foot local characteristics and major lower-extremity amputations in patients with diabetic foot, Wang et al found that the significant risk factors for amputation in this population were ulcer reaching bone, gangrene, hindfoot position, lower ankle-brachial index (ABI), infection, and peripheral arterial disease (PAD).[15]

In a study aimed at determining whether sodium-glucose co-transporter-2 (SGLT2) inhibitors were associated with a higher risk of lower-extremity amputation than dipeptidyl-peptidase-4 (DPP-4) inhibitors and sulfonylureas (SUs) in patients with type 2 diabetes, Yang et al found that use of SGLT2 inhibitors may increase the risk of amputation as compared with DPP-4 inhibitors, but not as compared with SUs.[16]  

Immune-nutritional status, as reflected in the prognostic nutritional index (calculated from the lymphocyte count and the albumin level) has been found to predict amputation in patients with lower-extremity PAD.[17]

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.[14]

A study by Arya et al found that the institution of a high-intensity statin regimen at the time of diagnosis of PAD was associated with a significant reduction in amputation and mortality as compared both with patients on lower-intensity statin regimens and with patients receiving only antiplatelet therapy.[18]

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.[19]

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.

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.

Anatomy

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 must 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-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 wound healing is a concern because most amputations are performed for compromised circulation (eg, PVD or 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. Most often, however, these skin-grafted areas do not tolerate the axial and shear stresses within the prosthesis and may have to be removed 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 weightbearing 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.

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, maintains a positive attitude, accepts the amputation, and continues to be a productive member of society.[20, 21]

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 following:

• Condition of the contralateral limb
• Comfort of the residual limb
• Comfort, function, and appearance of the prosthesis
• Social factors
• 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.[22]  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, and nearly two thirds (65%) required a below-knee amputation. Factors predictive 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

A retrospective analysis was conducted by Al-Thani et al to assess the effects of perioperative hemoglobin A1c (HbA1c) levels on the pattern and outcomes of lower-extremity amputation.[23]  Patients were categorized into five groups according to perioperative HbA1c level: (1) below 6.5 g/dL, (2) 6.5-7.4 g/dL, (3) 7.5-8.4 g/dL, (4) 8.5-9.4 g/dL, and (5) 9.5 g/dL or higher. Mortality was highest in group 1. Groups 4 and 5 had a lower risk of mortality after amputation, though the difference was not statistically significant.

In a study using data from the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database, Ahn et al assessed 2018 patients who had undergone transmetatarsal amputation and found that end-stage renal disease (ESRD) was associated with 100% increased odds of amputation failure, 128% increased odds of major amputation, and 182% increased odds of 30-day mortality.[24] A white blood cell (WBC) count higher than 10,000/μL and deep infection at the time of surgery were also independently associated with amputation failure.

Norvell et al used data from the Veterans Affairs Surgical Quality Improvement Program (VASQIP) database in an effort to develop a 1-year mortality risk prediction model for patients undergoing lower-extremity amputation secondary to complications of diabetes or PAD.[25]  This model, AMPREDICT-Mortality, included amputation level, age, body mass index (BMI), race, functional status, congestive heart failure, dialysis, blood urea nitrogen level, and WBC and platelet counts. It was found to be a validated parsimonious model that could be used to inform assessment of postamputation mortality risk in these populations.

In patients with peripheral vascular disease (PVD), the diagnosis is usually known because these individuals have had extensive vascular studies and have most often undergone attempts at revascularization. With progressive small-vessel occlusion and neuropathy, toes become gangrenous and pressure points develop trophic ulcers, allowing bacteria to take hold and eventually invade the bone.

Throughout treatment, costly measures are undertaken in attempts to salvage a marginally viable extremity, with the patient losing valuable productive time. The patient has often undergone multiple foot amputations and multiple debridements and is often wheelchair-bound for pain relief or for relief of pressure on the extremity. Additionally, the patient often has an ascending cellulitis due to venostasis or constant pain due to ischemic disease.

For trauma patients, the amputation may be the result of direct limb transection or a severe open fracture with an associated unreconstructable neurovascular injury. The limb is so severely injured that reconstruction is less functional than an amputation. The other end of the spectrum includes an unsuccessful prolonged limb-salvage attempt that leaves the patient with a painful nonfunctional limb. The salvaged limb often requires a protracted course of treatment that takes a psychological toll on the patient and absorbs significant emotional energy. The resulting limb may be less functional than a prosthesis would have been.

Osteomyelitis may be the result of systemic disease or of open fractures. Cultures or biopsy can often be used to identify the infecting organism. Gas gangrene due to Clostridium species is a very serious infection, often resulting in amputation. Clostridial myonecrosis infections develop rapidly, and patients present with symptoms of pain, sepsis, and delirium. Examination on palpation often reveals a brownish discharge and crepitation within the soft tissues.

Streptococcal myonecrosis infections develop more slowly than clostridial infections. Persons with diabetes mellitus often develop polymicrobial infections that involve anaerobic gas-forming gram-negative organisms.

Malignancies often manifest with pain. The patient is often referred for amputation following a workup for a tumor, after limb salvage is excluded as an option.

Congenital limb deficiencies and malformations are evident and are present since birth. With growth, functional difficulties and limitations develop that limit the patient's mobility.

Vascular evaluation (eg, via pulse examination, ankle-brachial index [ABI], angiography, computed tomography [CT] angiography [CTA], duplex ultrasonography [US], or magnetic resonance angiography [MRA]) before major lower-extremity amputation is feasible in the majority of patients and allows evaluation for revascularization options before the operation.[26]  

Laboratory studies

Amputation wound healing is a concern because most amputations are performed for compromised circulation. Standard laboratory studies are recommended, as are elective laboratory studies, depending on the patient's medical condition. Laboratory studies relevant to wound healing are as follows:

• C-reactive protein (CRP) - This inflammatory marker is an indicator of infection; a level lower than 1.0 mg/L indicates no infection, whereas a level higher than 8 mg/L indicates significant infection
• Hemoglobin - A measurement higher than 10 g/dL is required; oxygenated blood is necessary for wound healing
• Absolute lymphocyte count - A count lower than 1500/μL indicates immune deficiency and increases the possibility of infection
• Serum albumin level - A level of 3.5 g/dL or lower indicates malnutrition and a diminished ability to heal the wound

In patients with nonprogressive gangrene, inadequate physiologic conditions as determined by these laboratory studies should be optimized (eg, oral or intravenous (IV) hyperalimentation before amputation for malnutrition). When progressive infection or intractable ischemic pain is present, an open amputation can be performed and the soft tissues can be established later.

Imaging studies

Anteroposterior (AP) and lateral radiography of the involved extremity is obtained.

CT and magnetic resonance imaging (MRI) are performed for the patient's tumor workup or for osteomyelitis to ensure that the surgical margins are appropriate.

Technetium-99m (99mTc) pyrophosphate bone scanning has been used to predict the need for amputation in persons with electrical burns and frostbite. A 94% sensitivity rate and a 100% specificity rate have been reported in demarcating viable tissues from nonviable tissues.

Doppler US is used to measure arterial pressure; the area under the waveform is a measure of flow. In approximately 15% of patients with PVD, the results are falsely elevated because of the noncompressibility of the calcified extremity arteries. Doppler US has been used in the past to predict wound healing. A minimum measurement of 70 mm Hg is believed to be necessary for wound healing. The following values should be determined:

• Ischemic index (II) - This index is the ratio of the Doppler US pressure at the level being tested to the brachial systolic pressure; an II of 0.5 or greater at the surgical level is necessary to support wound healing
• ABI - The value at the ankle level is believed to be the best indicator for assessing adequate inflow to the ischemic limb; an index lower than 0.45 indicates that incisions distal to the ankle will not heal

Other tests

Transcutaneous oxygen pressure measurement is a noninvasive test that assesses the partial pressure of oxygen diffusing through the skin. This study can be applied to any area of intact skin and records the oxygen-delivering capacity of the vascular system.[27, 28] Transcutaneous oxygen pressure measurement is believed to be the most reliable and sensitive test for wound healing. Values higher than 40 mm Hg indicate acceptable wound-healing potential; values less lower 20 mm Hg indicate poor healing potential.

One study of transcutaneous oximetry reported an 88% sensitivity rate and an 84% specificity rate.[28] The pressure may be falsely low in areas of edema, cellulitis, and venous stasis changes.

An optimal residual extremity is covered with well-vascularized muscle, fascia, and skin. The skin is the most important tissue for healing of the amputation wound and should be handled with care. Careful assessment and handling of the soft tissues assists in creating a durable residual extremity that can withstand friction within the prosthesis. This allows a maximal limb-prosthesis interface that results in greater surface area for a force/stress distribution capable of end weightbearing.

The appropriate level must be planned preoperatively, with acknowledgment of the possibility that a more proximal level may be appropriate and that leaving the wound open for a staged procedure may also be appropriate. Decisions and adjustments are made on an intraoperative basis and planned for preoperatively. The options and possibilities are presented to the patient and family during the informed consent discussion.

Preoperative preparation includes the following steps:

• Appropriate preoperative antibiotics are administered in cases of infection, and prophylactic antibiotics are administered in cases of elective amputation or those resulting from trauma
• A tourniquet is placed on the limb prophylactically and used on a discretionary basis
• Vascular and bone instruments are requested
• A series of 45º chisels are obtained for osteomyoplastic reconstruction
• An appropriate strength saw for cutting bone is obtained (usually a power oscillating saw)
• Vessel ligatures are obtained

Two weeks after surgery, muscle-contraction exercises and progressive desensitization of the residual extremity are initiated. Desensitization is started with a towel for distal residual extremity pressure, and distal end bearing is started on a soft structure (usually a bed).

Prosthetic management is begun 6 weeks after surgery, depending on the condition of the extremity and wound. Some patients are not candidates for prosthetic limb replacement, because of poor balance, weakness, or cognitive impairment. To avoid disappointment and expense, a permanent prosthesis should not be ordered for these patients.

A multidisciplinary approach to treatment should be taken.[7, 8] Patients undergoing amputation should be evaluated for cognitive and physical abilities. Consultation with a physical therapist, social worker, and possibly a psychiatrist should be obtained to determine the patient's ambulatory potential. Allowing the patient to talk with someone who has undergone an amputation can also prepare the patient for future expectations and provide answers to questions the patient may not have considered.

Patients with peripheral vascular disease (PVD) should have an evaluation by a vascular surgeon to determine the feasibility of vascular reconstruction. Consultation with an internal medicine specialist is also recommended for evaluation of the patient's general medical health and any cardiovascular disease, as well as control of diabetes mellitus, if appropriate. Mortality after lower-extremity amputations in diabetic patients can be high.[12, 29] In addition, many patients with PVD are malnourished and may have additional cardiac or cerebral ischemic disease. Infections that develop in these patients are often polymicrobial, and broad-spectrum antibiotics are recommended in conjunction with wide debridement.

In clostridial myonecrosis infections, hyperbaric oxygen may be necessary in combination with the appropriate antibiotic treatment. Streptococcal myonecrosis requires appropriate antibiotic treatment and excision of the involved muscle compartment. This excision may make the amputation reconstructive difficult.

Great advances have been made in the treatment of severe lower-extremity trauma and PVD. Revascularization, internal fixation of fractures, microvascular techniques, and free tissue transfer procedures have improved and favorably enhanced the patient's outcome. Failure of these techniques when extensive efforts have been pursued may result in a negative patient outlook. Amputation may be viewed as a failure by both the surgeon and the patient. The patient may picture himself or herself as incomplete by societal standards. The current view is that amputation surgery is a reconstructive procedure intended to return a patient to an active life.

Compared with the changes that have taken place in the field of prosthetics, amputation techniques have changed little over the years. Even with a well-performed amputation and a well-fitted prosthesis, some patients have persistent symptoms of residual extremity pain, swelling, and a sense of instability, as well as have a decreased length of prosthetic wear. These patients pose a challenge for the reconstructive surgeon. The effects of previous surgery, altered anatomy, muscle and bone atrophy, and aerobic deconditioning are important variables in predicting the success of amputation surgery.

General principles for amputation surgery involve appropriate management of skin, bone, nerves, and vessels, as follows:

• The greatest skin length possible should be maintained for muscle coverage and a tension-free closure
• Muscle is placed over the cut end of bones via a myodesis (ie, muscle sutured through drill holes in bone), a long posterior flap sutured anteriorly, or a well-balanced myoplasty (ie, antagonistic muscle and fascia groups sutured together)
• Nerves are transected under tension, proximal to the cut end of bones in a scar- and tension-free environment, so as to reduce the chances that neuromas will form and be a source of pain; placing the cut nerves in a more proximal scar-free environment assists in decreasing potential irritation and pain; ligation of large nerves can be performed when an associated vessel is present
• The larger arteries and veins are dissected and separately ligated so as to prevent the development of arteriovenous fistulas and aneurysms
• Bony prominences around disarticulations are removed with a saw and filed smooth; diaphyseal transections can be covered with a local flexible osteoperiosteal graft; although maintaining the maximal extremity length possible is desirable, below-knee amputations are best performed 12.5-17.5 cm below the joint line for nonischemic limbs
• One application guide is to make a limb 2.5 cm long for every 30 cm of body height; for ischemic limbs, a higher level of 10-12.5 cm below the joint line is used because making limbs longer than this can interfere with prosthetic use and design ^[2]

Osteointegration has been performed in Sweden. This technique was initially applied in dental surgery for tooth loss, and the procedure involves a metal post, treated similarly to a total joint ingrowth prosthesis, secured to bone. Success has been achieved with replacement for thumb amputations. Case series with transfemoral amputations have been completed; however, long-term results are not available. The potential for postoperative infection and osteomyelitis is high.

Lower-limb reconstruction with a quad flap (consisting of parascapular, scapular, serratus, and latissimus dorsi free flaps combined on a single pedicle) has been described.[30]

Tourniquets are used on a discretionary basis in patients with vascular disease.[31] The extremity is prepared in a standard fashion. The skin incision is made as distal as is feasible, and dorsal and plantar flaps are created. Attention should be paid to ensuring viable margins so as to minimize the risk of subsequent osteomyelitis.[32] The flexor and extensor muscle groups are elevated as one musculofascial flap. The vessels are isolated and ligated, and the digital nerves are separated, distracted, and ligated at a more proximal level.

Osteoperiosteal flaps are elevated from the first and fifth metatarsals. The metatarsals are transected from dorsal to plantar at approximately 15º, with a cascade of shortening as one proceeds laterally. Care is taken to smooth off any rough borders with a file and to not leave any significant prominence beneath the skin. The osteoperiosteal flaps are sutured end-to-end and to each metatarsal, covering (closing) the exposed diaphysis. The flexor and extensor groups are sutured to each other through the fascial attachments, forming the myoplasty.

If used, the tourniquet is released and bleeding is controlled. The skin is contoured to the underlying myoplasty, allowing for a smooth transition. Penrose drains are placed for hematoma decompression. Sterile dressings and a well-padded posterior splint are applied.

The splint is removed after 2-7 days. Physical therapy is also instituted for patient education on transfers, desensitization of the residual extremity, aerobic conditioning, and upper-body strengthening. Full weightbearing is initiated at 4-6 weeks or pending wound healing.

Informed consent is obtained from all patients. In patients in whom a very short residual limb is expected, the possibility of knee disarticulation or amputation above the knee is also discussed. Every attempt is made to maintain the knee joint. The patient is positioned supine. A bump under the hip may be used to control rotation of the limb, and a tourniquet is applied. In patients with vascular disease, tourniquet use is on a discretionary basis. After preparing and draping of the extremity, previous incisions are used, if appropriate. No differences in wound healing between anterior-posterior, oblique, and medial-lateral incisions have been reported.

After incision, dissection is carried down to the muscular layer, then carried more proximally, with the anterior, lateral, and posterior compartments identified and isolated. If a long posterior muscle flap was used for anterior coverage in the primary amputation, care should be taken to preserve the length of this posterior muscle compartment. During isolation of the muscle compartments, care should also be taken to maintain the fascial attachments to the musculature for later myoplastic reconstruction.

After isolation of the muscle compartments, the main neurovascular structures are identified, released from scar tissue, and separated. This should include the tibial nerve, artery, and vein; the superficial and deep peroneal nerves and the peroneal artery and vein; the sural nerve; and the saphenous nerve and vein. The identified nerve should be transected as high as possible and allowed to retract into the soft-tissue bed. The artery and nerve are separated and ligated in a separate fashion.

Once soft-tissue dissection is completed, attention is turned to the osseous structures. The periosteum is incised from anterior to posterior on the fibula and tibia. With a 45° chisel, an osteoperiosteal flap is elevated medially and laterally in such a way as to maintain the proximal attachment. Small cortical fragments are left attached to the periosteum.

Once the osteoperiosteal flaps are created, any exposed cortical bone that remains is resected to the same level, thereby facilitating the suturing of the osteoperiosteal flaps. This requires no more than 1.5-2 cm of bone to be resected. The medial tibial flap is sutured to the lateral fibular flap, and the lateral tibial flap is sutured to the medial fibular flap, resulting in a tubelike structure.

In short or very short residual extremities, free osteoperiosteal grafts are harvested from the proximal tibia, contralateral extremity, or iliac crest to maintain bony length. This may also be performed on any length of residual extremity. The authors have used free osteoperiosteal grafts harvested from the removed limb in primary amputations without difficulty and with complete synostosis formation.

Some short transtibial extremities exhibit abduction of the fibula (abducted fibula) secondary to the pull of the biceps femoris. This may lead to a lateral pressure point and prosthetic difficulties. The fibula is reduced into an adducted position and a lag screw placed into the proximal tibiofibular joint, stabilizing this dynamic deformity with or without an arthrodesis of this joint.

The mobilized musculature is then brought distally, covering the osteoperiosteal bridge, and a myoplasty is completed, suturing the posterior musculature to the anterior and lateral musculature. (If there is a length discrepancy, then a myodesis can be performed.) However, the goal is to provide soft-tissue coverage for the distal aspect of the residual extremity.

The Ertl technique, an osteomyoplastic transtibial amputation procedure that involves forming a tibiofibular bone bridge to provide a stable tibiofibular articulation that may be capable of some distal weightbearing, may be used to create a highly functional residual limb.[33] Further study is needed to define patient selection, technical details, and postoperative care for this technique.

After the completion of the myoplasty, the skin is mobilized over the underlying myoplasty. Care is taken to reapproximate the skin in a symmetric fashion, leaving neither "dog ears" nor crevices. Drains are placed to prevent hematoma formation. After sterile dressings are applied, the extremity is placed in a plaster splint in extension. The splint is removed after 2-7 days.

The use of a temporary total-contact end-bearing prosthesis is begun after 5-8 weeks. Physical therapy is also instituted for patient education on transfers, desensitization of the residual extremity, aerobic conditioning, and upper-body strengthening.

The patient is informed of the surgical risks and complications. All attempts are made to maintain residual extremity length to avoid the necessity of increased energy expenditure. In secondary reconstructive cases, the previous operative report should be reviewed and attention directed toward treatment of the muscles and nerves, which may assist in the exposure and dissection.

The extremity is prepared in a standard fashion. A tourniquet may not always be feasible, and a sterile tourniquet may be used. A bump is placed under the hip of the involved extremity to assist with rotational control. The previous incisions are identified and used, if appropriate.

Dissection is carried to the muscular layer. The muscles are often retracted and atrophic, necessitating proximal dissection and muscle identification. The adductors, abductors, quadriceps, and hamstrings are isolated in their respective groups. The fascial envelope is maintained for subsequent myoplasty. The neurovascular structures are identified and separately isolated. Separating the nerve from the artery is important. In this manner, pulsatile irritation of the nerve is avoided.

The nerve trunk is mobilized by blunt dissection and distracted and transected at a higher level, which allows retraction into the soft-tissue surroundings. If a tourniquet has been used, it may be released to evaluate bleeding. The vascular structures are often friable and must be handled carefully to avoid proximal retraction. The artery and associated veins are separately ligated to avoid arteriovenous connections.

Attention is directed toward the distal residual femur. The periosteum is incised from anterior to posterior. With a 45° osteotome, medial and lateral osteoperiosteal flaps are elevated, with their proximal attachments maintained. Elevation of the flaps is aided by rotating the chisel 180°, lifting and maintaining the osteoperiosteal attachments. The femur is transected at the level of the osteoperiosteal flaps, with minimal femur necessitating removal. The medial and lateral flaps are sutured together, and circumferential periosteal sutures are placed, occluding the end of the open medullary canal.

An alternative method is to prepare a longer medial- or lateral-based osteoperiosteal flap, securing it to the opposing and circumferential periosteum, achieving medullary coverage.

Myoplasty is performed by suturing the antagonistic muscle groups to each other and anchoring them into the periosteum, covering the osteoplasty. The adductors are sutured to the abductor group first, or they are anchored to the lateral femoral periosteum. The abductors are imbricated over the adductor attachment and additionally secured to the periosteum, anteriorly and posteriorly. The flexors are sutured to the extensor group and the underlying adductor/abductor groups, centralizing the distal femur in a muscular envelope.

The skin is fastened to the underlying myoplasty in a symmetric fashion, with care taken to avoid dog ears and invaginations of the incision. A smooth contour is the goal, allowing a better limb-prosthesis interface. Penrose drains are placed before the closure is completed.

Postoperatively, the residual extremity is placed in an Ace wrap hip spica or a bulky plaster splint, depending on the length. Sutures are removed after 2-3 weeks, depending on wound healing. A temporary total-contact end-bearing prosthetic fitting is coordinated with the patient's prosthetist 5-8 weeks postoperatively. Physical therapy is initiated for transfers, desensitization, range of motion, aerobic conditioning, and upper-body strengthening.

Postoperative dressings and treatments vary, each with advantages and disadvantages. There are four generic types of postoperative dressings available, as follows:

• Soft dressings - These dressings do not control postoperative edema
• Soft dressings with pressure wrap - These dressings require an even distribution of pressure to avoid possible limb strangulation
• Semirigid dressings - These include plaster splints and Unna Paste Bandages held in place with a stockinette; they have the same advantages that rigid dressings do, except that no immediate postoperative prosthesis can be used
• Rigid dressings - Many such dressings are commercially available, and intraoperative prosthetic assistance may be required; potential advantages include residual extremity maturation, decreased edema, less pain, wound protection, and early mobilization in combination with an immediate postoperative prosthesis; disadvantages include poor access to the wound and excessive pressure, leading to wound necrosis

Physical therapy for transfers and assisted ambulation are initiated. Assisted ambulation is at the discretion of the surgeon and therapist, depending on the patient's rehabilitation potential. Precautionary instructions regarding falling are provided to the patient to avoid the potential of injuring and opening the postoperative wound.

A consultation should be obtained for psychosocial and emotional issues. Support groups for people who have undergone amputations and discussion with someone who has undergone amputation are of assistance.[7, 8]

Incorporated into the preoperative and operative plan are (1) careful handling of tissues and (2) reconstruction of the limb to the best anatomic and physiologic condition possible, in hopes of avoiding known complications. Common complications include the following:

• Wound breakdown and skin problems
• Swelling
• Edema
• Joint contractures
• Pain
• Phantom limb sensation

Wound healing in the patient with vascular disease can be severely compromised by the patient's underlying disease or by skin closure under tension. Small areas of wound breakdown should be allowed to demarcate, and these can be treated with open or wedge resection. Larger areas with exposed muscle and bone may necessitate revision of the amputation, shortening of the bone, and closure without tension.

Skin difficulties are encountered between the residual limb and socket interface and can usually be avoided with good hygiene. The socket liner should be cleaned regularly and kept dry and free of topical soap residues.

The use of incisional negative-pressure wound therapy (iNPWT) may help reduce incisional complications after nontraumatic lower-extremity amputations.[34]

Folliculitis of the residual limb can be avoided by not shaving. When folliculitis is present, it can be treated with oral antibiotics. Similarly, hidradenitis should be managed with appropriate hygiene and occasional oral antibiotics.

Postoperative edema may occur and further compromise wound healing. This problem can be minimized by performing medullary canal closure and myoplasty. Postoperative bulbous swelling of the distal residual extremity is due to tight proximal dressings. This may lead to congestion and subsequent wound and prosthetic-fitting difficulties. Similarly, if the prosthesis is too tight proximally, bulbous swelling and venous congestion occur and may lead to cellulitis.

Persistent residual extremity swelling after maturation is most often due to a poor prosthetic fit or medical problems. Chronic swelling without treatment may lead to verrucous hyperplasia. Treatment consists of a total-contact socket with frequent alterations as needed to accommodate volume changes.

Joint contractures of the hip or knee may occur at the time of surgery or postoperatively from lack of activity and prolonged sitting or wheelchair ambulation. At the time of surgery, overtightening of the muscles should be avoided and appropriate postoperative positioning maintained.

In patients who have undergone transtibial and transfemoral amputations, prolonged sitting with the hip and knee flexed should be avoided. Patients who have undergone transfemoral amputations should be instructed to lie in the prone position multiple times during the day to stretch the hip musculature. Physical therapy should be initiated for early range-of-motion instructions. When present, joint contractures can make prosthetic fitting and wear very difficult. Dynasplint treatment may help in achieving residual limb extension.

Phantom limb sensation (ie, the sensation that the amputated limb is still present) occurs in nearly all patients who undergo amputations. It tends to decrease gradually over time. Phantom limb pain is described as a painful burning sensation in the amputated limb, and it is more common than was previously thought. Contributing causes of residual limb pain include neuromas at the level of the amputation, which become adherent to skin, muscle, and bone. This can lead to direct nerve-end stimulation or pain from traction with extremity motion. Continuous pulsatile arterial stimulation of the nerve occurs when the neurovascular structures are ligated together.

In patients who have undergone transtibial amputations, nerve stimulation can occur from compression of the nerve between the mobile fibula against the tibia. Additional causes of pain include the following:

• Incompetent soft-tissue envelope
• Prominent bone ends and spurs with associated bursitis
• Deep tissue scarring
• Ischemia in patients with vascular disease

Noninvasive treatment modalities may be tried initially, such as desensitization therapy, progressive and continued prosthetic wear, intermittent compression, medications, transcutaneous nerve stimulation, or a trial of proximal nerve blocks. Reconstructive surgery is often necessary to remove the neuromas and place them in an area free of scarring and adhesions and to reorganize the tissues to the most anatomic position possible through osteomyoplasty.

Targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) procedures can improve patient-reported outcomes for the treatment of symptomatic neuromas after amputation. Hoyt et al, in a study aimed at determining what nerves most often required secondary pain intervention such as TMR or RPNI after conventional amputation, found that for symptomatic neuromas above the knee, the sciatic nerve was most likely to require intervention, whereas after transtibial amputation, the tibial nerve and the common or superficial peroneal nerve were most problematic.[35]

Depressive symptoms may develop after dysvascular amputation.[36]

A study (N = 4162) using data from the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database identified the following predisposing factors for four complications after leg amputation[37] :

• Surgical infection - Preoperative open, contaminated, or dirty/infected wounds; longer intraoperative times; development of sepsis prior to surgery; admission of patients from home or another hospital
• Additional service - Preoperative open, infected, or dirty/infected wounds; height; weight; total length of hospital stay; ethnicity
• Deep vein thrombosis (DVT) - Preoperative congestive heart failure; large decreases in body weight; total length of hospital stay
• Sepsis - Preoperative functional heath status; total length of hospital stay; amputations conducted as emergency cases; preoperative acute renal failure; open or infected wounds; sepsis; contaminated or dirty/infected wounds