Lower extremity major amputations are often complications of peripheral arterial disease (PAD), neuropathy, and sepsis due to soft tissue infection. Peripheral arterial disease alone, or in combination with diabetes mellitus, contributes to more than half of all amputations. Other risk factors to elucidate in the patient’s history include chronic kidney disease, coronary artery disease, functional status, smoking history, and history of TIA or stroke.
Indications for lower extremity major amputation includePAD after revascularization attempts have been made and failed; foot sepsis; and trauma. Primary amputation is the most effective therapy for non-ambulatory patients with advanced chronic limb-threatening ischemia especially in the presence of limb contraction. This should be documented in the patient’s medical record.43
A thorough exam is required prior to a major amputation, with a special focus on the level of arterial perfusion present at possible amputation levels. Further, the amputation margin should be proximal to existing wounds or non-viable lower extremity tissue.
Pulse examination can assist in determining the level of amputation. For example, lack of easily palpable femoral pulses may predict poor healing of a below knee amputation, and palpable popliteal pulse is more likely to predict healing of a below knee amputation (BKA).
To further determine type and level of amputation, the limb should be evaluated for nonviable tissue (dry gangrene, wet gangrene, fixed mottling in acute limb ischemia), spreading infections compromising survival (necrotizing fasciitis, chronic ulceration, and osteomyelitis), and disabling conditions (non-functional/ limited limb function, intractable pain, or nonhealing diabetic wounds).
Imaging of the lower extremity prior to amputation is important in determining the level of amputation. Arterial duplex, Doppler, and thigh pressures can be used to assist in determining the arterial perfusion that is available to support a particular level of amputation. Transcutaneous oxygen level measurement can provide guidance regarding adequacy of perfusion at a proposed amputation level, with a measurement of greater than 40 mm Hg being associated with successful healing.144
CT angiography can be employed to assess arterial anatomy if other non-invasive testing is inconclusive.
Plain X-ray can assess for infection, and prior orthopedic intervention or hardware that may interfere with amputation. In these cases, specialized saws may be necessary to cut through the metal, or orthopedic surgery consultation may be required to remove the hardware prior to amputation. MRI can be used to assess for infection with bony involvement. The amputation margin should be proximal to any infected regions.
Medical Management and Lifestyle Changes
- Smoking cessation: A multidisciplinary comprehensive smoking cessation approach should be utilized until tobacco use has been stopped.
- Diabetes mellitus: For patients with PAD, it is important to optimize diabetes control (hemoglobin A1c goal of <7.0) without hypoglycemia.
- The SVS recommends therapy with aspirin (75-325 mg daily). Clopidogrel is recommended (75 mg daily) as an alternative to aspirin for antiplatelet therapy. Dual antiplatelet therapy, with aspirin and Plavix, is not better than aspirin alone.
- Hypertension: Anti-hypertensive control should be focused on a goal blood pressure of less than 140/90, with ACE inhibitors and ARB recommended as first line. The use of beta blockers (hypertension, cardiac indications) should be considered if symptoms are due to atherosclerosis.
- For patients with dyslipidemia, treatment with a statin to achieve a target low-density lipoprotein cholesterol (LDL-C) level of <70 mg/dL is recommended. If LDL-C goal is not achieved by statin therapy, then PCSK9i should be considered. Even if LDL-C is at goal, statin therapy should be initiated and continued due to its overall pleiotropic beneficial effects.
Risk Stratification for Surgery
Because cardiac disease is so prevalent among patients with peripheral vascular disease, an ECG should be performed in all patients and if time allows, cardiac risk stratification should be obtained.
Chest radiography may be helpful in some patients if undiagnosed underlying disease is suspected on the basis of the history and physical examination. In select patients, more advanced testing may be appropriate, such as cardiac stress testing or pulmonary function evaluation when cardiac or pulmonary disease is suspected. The associated comorbidities and risk factors, including smoking cessation, should be managed optimally before surgery, similar to patients undergoing any major vascular surgical procedures. There are well-accepted, published guidelines from most of the medical subspecialties to guide the preoperative evaluation, including those from the American Heart Association and the American College of Cardiology for the optimal preoperative cardiac evaluation for patients undergoing major noncardiac surgery.31
A multidisciplinary approach to care can optimize outcomes. Medical specialists and team members can assist patients with risk factor modification, such as smoking cessation, maintaining glycemic control, normalizing blood pressure and lipid levels, maintaining antiplatelet therapy, thereby promoting a positive patient experience. Discharge planning should also be considered at the time of surgical planning.
When a patient presents with a limb that is life-threatening (e.g., necrotizing fasciitis, sepsis, acute limb ischemia) the patient may require a staged amputation approach. An open (guillotine) amputation can be performed first in order to obtain source control. The planned second stage involves delayed closure and can be scheduled when the patient is medically stable. This two stage approach may lead to decreased residual limb infections and need for revision.145
When assessing patients who need a major amputation, it is important to understand the risk of postoperative morbidity and mortality.7 Myocardial infarction, pulmonary complications, and renal failure are frequent after lower extremity amputations.
By the time a patient is being assessed for a major lower extremity amputation, most other management techniques have been tried and failed. It is still important to optimize patients’ comorbid conditions (smoking cessation, high-density lipoproteins (HDL), HTN, Type 2 diabetes mellitus [T2DM] optimization) and optimize arterial perfusion as much as possible.
In many cases, the patient presents with a severely infected extremity that cannot be managed with aggressive debridement and antibiotics. This represents a surgical emergency, and the patient should undergo amputation expeditiously without further testing or optimization. However, prior to elective or semi-elective amputationsmedical optimization of peripheral arterial disease (including possible inflow revascularization), diabetes management, smoking cessation, and optimization of comorbid conditions including CKD and CAD should be pursued.
Given the high risk of coronary disease, all patients should be on aspirin (75-100 mg daily). The addition of rivaroxaban 2.5 mg twice daily to aspirin monotherapy may improve cardiovascular outcomes (COMPASS trial).89 Aggressive statin therapy should also be employed.
Perioperative transfusion of packed red blood cells should be performed if the hemoglobin level is less than 7 g/dL. Recent EKG should be obtained for all patients. In some patients, and in consultation with cardiology, an echocardiogram, cardiac stress test, or cardiac catheterization may be helpful.
a. Diabetes Mellitus
Glycemic control should be considered per the current guidelines of the American Diabetes Association.18
Standard preoperative labs should be ordered and reviewed prior to surgery. This includes complete blood count (CBC), basic metabolic panel (BMP), PT/INR, hemoglobin A1C, albumin, and pre-albumin.
Preoperative Medication Adjustment
- Anticoagulation: Anticoagulation should be held in the periprocedural period. Heparin bridging may be required, especially for mechanical mitral valve replacement.
- Antiplatelet and anti-hypertensive medications: Aspirin and other antiplatelet medications and anti-hypertensives should be continued through the procedure.
- Preoperative antibiotics:
- Recommended within one hour of skin incision
- Intravenous antibiotics that are appropriate for skin flora are adequate for amputations that are not complicated by soft tissue infection or wound infection
- In patients with active wounds, wound cultures should be obtained in order to tailor antibiotic treatment.
- Anaerobic coverage should be used in diabetic patients.
- Continued use of antibiotics post operatively can be considered.
- Thromboprophylaxis: Patients undergoing major amputations are at high-risk for thromboembolism due to the nature of surgery; therefore, LMWH or heparin subcutaneous should be administered.
- ACE Inhibitors: If significant volume depletion is anticipated, it is suggested to hold ACE inhibitors and angiotensin receptor antagonists on the morning of surgery and restarting these agents after the procedure, once euvolemia has been achieved.
- Diabetes Mellitus: It is suggested to hold metformin at the time of administration of contrast material among patients with an eGFR of <60 mL/min or up to 48 hours before administration of contrast material if the eGFR is <45 mL/min and restarting no sooner than 48 hours after administration of contrast material as long as renal function has remained stable. Diabetic patients who receive intermediate or long-acting insulin should receive half the scheduled dose when nil per os (NPO) in preparation for surgery. Glycemic control should be considered per the current guidelines of the American Diabetes Association.18
Recommended Preoperative Consultations
Some patients with chronic wounds and rest pain requiring amputation may benefit from proper counseling on the subject prior to elective amputation. Preoperative teaching and evaluation for postoperative needs can be addressed with discharge planning, which include coordination with a prosthetist and amputee advocate. Unfortunately, since many amputations are performed in the urgent and emergency setting, counseling, medical management, and stumpcare are provided in the postoperative period.
General: While some minor amputation procedures, such as toe amputation, can be safely performed without anesthesia involvement, most patients will benefit from anesthesia care team involvement, as patients frequently:
- Are older with high ASA classification.
- Display significant comorbidities, including peripheral arterial disease, diabetes mellitus, hypertension, chronic kidney disease, coronary artery disease, poor functional status, smoking history, and history of TIA or stroke.
- Are at risk for respiratory or hemodynamic decompensation.
- Are unable to tolerate awake procedure or supine position for a prolonged period of time (e.g., due to back pain).
The acuity of illness underlying the need for amputation, can range from a stable (i.e., “semi elective”) procedure, to a highly unstable clinical presentation with the patient requiring hemodynamic support and mechanical ventilation (e.g., sepsis and/or unstable coronary artery disease).
The reported perioperative mortality rates range from 0.9% to 14.1% for BKA, and 2.8% to 35% for AKA.146, 147 Consequently, the perioperative anesthesia process should be meticulous and identify potential risk factors—with particular attention to cardiovascular risk factors, anticoagulation, diabetes, and sepsis.
a. Anesthesia Management
i) Anesthesia Techniques
Interestingly, retrospective analysis of the American College of Surgeons National Surgical Quality Improvement Project (ACS-NSQIP) database did not identify any significant effects of the mode of anesthesia on perioperative outcomes after major lower extremity amputation in the geriatric population.148 Anesthesia type was not an independent risk factor for wound, cardiac, pulmonary, renal, stroke complications, or postoperative mortality.148 Of note, general anesthesia was more likely to be used by general and orthopedic surgeons than by vascular surgeons.148 The operative time was not affected by anesthesia technique, though general anesthesia was associated with a lower time from anesthesia to the operation.
- General anesthesia: May be required in select patients (1) with contraindications to neuraxial anesthesia or peripheral nerve blocks, (2) unable to be supine for prolonged periods of time, or (3), requiring a complex surgical intervention. Endotracheal tube (ETT, “tube”) provides better protection from aspiration and thus may be preferred over LMA (high co-morbid burden may increase the risk of aspiration).
General anesthesia can be maintained using either: (1) inhalational agent (“gas”): Sevoflurane, with a “sweet” smell, is commonly used compared to Desflurane as the latter has a more pungent smell/taste (i.e., avoid in patients with irritable airway). Desflurane was, however, reported to be associated with a faster emergence;96, 97 (2) total intravenous anesthesia [TIVA]; commonly consisting of a combination of infusions (e.g., propofol, opioid, lidocaine, ketamine) offers another approach to maintain general anesthesia. TIVA was also found to reduce nausea/anesthesia (propofol).98
- Neuraxial technique (spinal and/or epidural anesthesia) +/- sedation: May provide adequate analgesia while avoiding the risk of general anesthesia. Notably, an epidural catheter allows for postoperative pain control. Choice of local anesthetic drug will depend on expected duration of the surgical procedure.
- Regional anesthetic techniques (e.g., combination of single shot femoral and sciatic nerve blockade): Represents safe, although less commonly utilized alternatives, especially if the use of lower extremity tourniquet is considered. All anesthetic nerve blockades can be done safely under ultrasound guidance. The choice of local anesthetic drug will depend on expected duration of surgical procedure. Mepivacaine is suitable for procedures of up to two hours, Ropivacaine or Bupivacaine may be preferred for procedures expected to take longer than two hours.
- Sedation: All local, neuraxial or regional anesthetic techniques can be supplemented with light to moderate sedation such as propofol or dexmedetomidine drips for patient comfort. Opioids may be added for analgesia/sedation as well.
ii) Monitoring and Access
All patients require the standard mandated by the American Society of Anesthesiologists including oxygenation (peripheral SpO2), ventilation (CO2 monitor), circulation (ECG and BP) and temperature monitoring.67 In addition, all patients need an adequate IV-access and continuous oxygen supply.
- Indwelling Arterial Catheter: may be considered in patient with cardiac, pulmonary, renal, or metabolic conditions requiring continuous hemodynamic monitoring and/or blood sampling.
- Central Venous Line: Intra- and postoperative use of vasoactive drips or large fluid shifts may require the placement of a central venous line.
- Brain Oxygenation: Monitoring using cerebral oximetry (similar principle as peripheral pulse oximetry) may be considered in patients who have a history of or who are at-risk for stroke.129
iii) Intraoperative Concerns
- Hypotension: The cardiovascular changes associated with aging are largely the result of stiffening of the heart and the vascular system, leading to systemic hypertension, left ventricular hypertrophy, and to a decreased range of acceptable left atrial filling pressures. Consequently, intraoperative hypotension should be treated primarily with peripheral vasoconstrictors (e.g., phenylephrine, an alpha-1 adrenergic receptor agonist) and judicious volume administration.130 Notably, fluids should be administered based on clinical evidence of hypovolemia, not simply on the basis of hypotension alone.
- Hypothermia: In the elderly, hypothermia could be detrimental, as thermoregulation becomes impaired with aging.69, 70 proactive methods for temperature regulation should be aggressively utilized.7
d. General & Procedure-Specific Concerns
General intraoperative concerns: Skin preparation (CHG wipe timeout for three minutes to dry), Foley placed by trained staff, shaving performed with clippers, normothermia.
Postoperative care of patients who have undergone major amputation requires a multidisciplinary approach including team members (nurses, physician extenders) , case managers, nutrition, pain management, physical therapy, occupational therapy, psychotherapy, medical care of comorbid conditions, and wound care. One third of postoperative mortality occurs after discharge from acute inpatient care, so therefore close post discharge follow up is recommended. Discharge to a rehabilitation facility may be appropriate. To prevent thromboembolic events, patients should continue DVT prophylaxis while hospitalized.
Steps Prior to Discharge
- General: The most common mechanical complication after transtibial amputation is knee contracture. To prevent this, surgeons may use a soft knee immobilizer or rigid stump dressings including casting, or a stump protector.
- Wound Care: Immediate postoperative wound care is tailored to the indication for amputation. In the case of transtibial amputations, preventing knee contractures is of paramount importance. The postoperative dressing should stay in place until postoperative day three if the wound bed was clean, the skin was closed, and if the postoperative dressing is not saturated. Otherwise, the dressing should be removed earlier, and the incision line evaluated for signs of bleeding or infection. It is also important to keep transfemoral amputations clean, as they are at higher risk of contamination from urine or stool due to proximity to the trunk.
- Pain Control: Acute pain following amputation is expected. Narcotic analgesia in the form of intravenous and oral medications are commonly used. If the patient had a nerve block as operative anesthesia, it may still be effective for hours following the procedure. Reduction in pain allows for patients to initiate mobility and rehabilitation services sooner in their postoperative course. Phantom limb pain is common after amputation, and is experienced by approximately 25% of patients. Mirror therapy has been used as an effective treatment. Gabapentin (Neurontin) or Pregabalin (Lyrica) pharmacotherapy can also be considered.
Physical Therapy: Mobilization is the priority after any major amputation. This includes mobility in the bed and strengthening the upper limbs and remaining limb. Physical therapy and occupational therapy can be initiated postoperative day one if appropriate pain management is achieved and appropriate based on the patient’s previous level of mobility.
Steps After Discharge
- Follow-up: Follow up call within the first week after surgery.
- Office / Telehealth Visit:
- Follow-up in clinic within a month after surgery unless indicated sooner.
- Fitting should be performed once the skin has fully healed, at least 8 weeks after amputation. First fitting should be with a firm stocking to help shape and form the residual limb for a prosthesis. Rehabilitation and prosthesis training is necessary during this time. Early introduction to a certified prosthetist, and the use of amputation support groups can also expedite the post op rehabilitation process.
- Medication: The use of long-term medications can be coordinated with the patient’s primary care provider and can include the use of statins or a PCSK9 inhibitor in order to achieve optimal LDL control. In addition, anti-platelet agents, anti-hypertensive agents, and agents for glycemic control should be prescribed, as indicated.