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Lee J. Sanders, D.P.M.Danielle/Nicole, please change M.D. to D.P.M., and add my middle initial "J".
02-04-2011
- Minor lower extremity amputation (LEA): toe(s), ray(s), transmetatarsal and midfoot amputation.
- Major lower extremity amputation (LEA): below-knee- transtibial amputation (BKA) of the lower leg distal to the tibial tuberosity; above-knee-amputation (AKA) of the leg through the femur (supracondylar, midthigh or high thigh).
- Guillotine amputation: an open amputation for uncontrolled pedal sepsis, through a circular incision down bone, allowing for quick removal of septic focus and direct examination of muscle compartments for extension of infection.
- Autoamputation: Dry gangrene allowed to demarcate and proceed to amputation without surgical intervention.
- Approximately 2/3s of all LEAs occur in people with diabetes (leading cause).
- Risk factors: peripheral arterial disease, peripheral sensory neuropathy, ulceration, infection, renal disease, smoking and prior amputation
- Half of all LEAs occur >65 years of age.
- In 2003, rate per 1000 persons with DM = 5.0 among blacks and 3.2 among whites in U.S.
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Diabetic foot ulcers (DFUs) precede 85% of amputations.
- A higher percentage of distal amputations (toes, rays and transmetatarsal) are performed in individuals with diabetes; >50% of amputations in persons with diabetes are performed at the level of the foot (40% toe, 13% transmetatarsal)
- Diabetes is most strongly associated with femoral-popliteal and tibial (infrapopliteal) atherosclerotic disease.
- Diagnosis of peripheral vascular disease (PVD) requires a detailed assessment for absence of femoral, popliteal and pedal pulses.
- Ankle-brachial index (ABI): the ratio of the systolic blood pressure at the ankle divided by systolic blood pressure at the arm (normal ABI = .91-1.30; severe ischemia = ABI <0.4). (Hirsch)
- In patients with DM, ABI's may be artifactually elevated due to calcification of the arterial wall; 10% will have non-compressible vessels.
- Anatomic studies: (1) Gold standard for vascular imaging is conventional x-ray angiography but should only be performed when considering a revascularization intervention; (2) Duplex ultrasound (allows direct visualization of vessels); (3) Magnetic Resonance Angiography (noninvasive with minimal risk); and (4) CT Angiography (CTA). (Hirsch)
- Regardless of the imaging tool used, arterial stenosis is seen as narrowing of vessels, abrupt interruption of flow or inability to visualize a branch.
- Pulse volume recordings provide a qualitative assessment of blood flow; toe pressures >68mmHg, and transcutaneous oxygen (TcPO2) levels >30mm Hg can accurately predict healing of a transmetatarsal, midfoot or below knee amputation.
- See modules on peripheral neuropathy and diabetic foot ulcers for diagnosis of these important risk factors.
- Relies on accurate diagnosis of risk factors for amputations
- PVD: absent pedal pulses, dependent rubor, pallor on elevation, loss of hair on dorsum of the foot, shiny scaly skin, thickening of the toenails, intermittent claudication.
- Acute limb ischemia (ALI): sudden decrease in limb perfusion that threatens tissue viability; 5 P's: pain, pallor, pulseless, paresthesias and paralysis.
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Critical limb ischemia (CLI): chronic ischemic rest pain in the forefoot, toes and/or leg, ischemic ulcers, tissue necrosis or gangrene attributable to objectively proven arterial occlusive disease.
- Moderate to severe aerobic or anaerobic infection with tissue necrosis.
- Rutherford classification of peripheral arterial disease severity used to classify degree of ischemia and salvageability of the limb. (Hirsch)
- Treatment for ALI and CLI is described in the Gangrene module.
- Among those with unreconstructable disease ~40% of the cases of CLI will require major amputation within 6 months of initial diagnosis. (Hirsch)
- Level of amputation is determined by degree of tissue damage and infection, tissue oxygen perfusion, rehabilitation potential of the patient and the clinical judgement of the surgeon (skin temperature, hair growth, tissue bleeding, viable muscle and wounds without tension).
- Goals of minor LEA: (1) eliminate non viable tissue, (2) provide a foot that that has the best chance to heal, (3) provide a functional and cosmetically acceptable partial foot, (4) prevent major amputation of the leg.
- Goals of major LEA: (1) eliminate non viable tissue, (2) provide a stump that has the best chance to heal, (3) provide a stump with best chance of long-term function.
- Close follow-up of patients post major LEA is needed, because they have a 4% - 30% risk of mortality at 30 days, and a 20% - 37% risk of significant morbidity (MI, stroke and infection).
- Intensive treatment of all risk factors is needed because of poor overall prognosis: patient survival in the National Surgical Quality Improvement Program (NSQIP) amputation series for BKA and AKA was 57% and 39% at 3 years. (Nehler)
- Also requires intensive prevention program for surviving limb, because 15% of patients with initially successful BKA will be converted to an AKA at 2 years, likely due to more proximal atherosclerotic occlusive vascular disease, flexion contracture of the knee and the development of non-healing wounds on the BKA stump. (Nehler)
- Another 15% of patients with initially successful BKA will suffer a major contralateral amputation.
- Comprehensive multidisciplinary foot care programs can reduce amputation rates by 45%- to 85%.
- The above statistics highlight the importance of close follow-up and intensive preventive measures.
- Major LEA confers a poor overall prognosis.
- Hirsch AT, Haskal ZJ, Hertzer NR, et al.;
ACC/AHA 2005 Practice Guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic): a collaborative report from the American Association for Vascular Surgery/Society for Vascular Surgery, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, Society of Interventional Radiology, and the ACC/AHA Task Force on Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Peripheral Arterial Disease): endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation; National Heart, Lung, and Blood Institute; Society for Vascular Nursing; TransAtlantic Inter-Society Consensus; and Vascular Disease Foundation.;
Circulation;
2006; Vol.
113; pp.
e463-654;
ISSN:
1524-4539;
PUBMED: 16549646
Rating:
Basis for recommendation
Comments:The ACC/AHA guidelines can be downloaded for free from the American Heart Association. http://circ.ahajournals.org/cgi/reprint/113/11/1474
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