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The Diabetic Foot - An Overview Convertir en PDF Version imprimable Suggérer par mail

John M. Embil, M.D., FRCPC
Kristin S. Reid, BSc (Med)
Section of Infectious Diseases, Department of Medicine,
University of Manitoba,
Winnipeg, MB

Introduction
The term "diabetic foot" is somewhat misleading as this would imply that it is only the foot that suffers from diabetes. In reality, diabetes mellitus, a multi-system disease resulting from altered glycemic control either from a complete absence of insulin production (type 1) or from relative insulin resistance (type 2). Regardless of whether diabetes has its onset during childhood or in the adult years, it is associated with a multitude of end organ complications which may have devastating consequences. The goal with any chronic disease is to manage optimally the underlying condition so to prevent complications. The same holds true for diabetes and complications affecting the foot.


 

Epidemiology
Diabetes mellitus is multi-system disease resulting in vasculopathy, nephropathy, retinopathy, and neuropathy. In the lower extremity, complications arising from ischemia and/or neuropathy may include pain or discomfort, deformity (i.e. Charcot foot, claw toes, prominent metatarsal heads), ulcers, infection and may ultimately result in amputation of a digit(s), forefoot or an entire lower extremity. Peripheral neuropathy increases risk of plantar ulceration seven-fold.1 Without the presence of peripheral neuropathy, it is unlikely that the person with diabetes will develop a plantar ulceration. Important contributing factors for the development of a plantar ulceration include peripheral vascular disease, infection and extensive or repetitive trauma.2 Approximately 15% of persons with diabetes will develop a foot ulcer in their lifetime and between 6% to 20% of all hospitalized persons with diabetes have a complication related to a foot ulcer.3 These individuals with a diabetic foot ulcer also have an increased mortality.4 Non-healing plantar ulcers are an instigator for most (84%) lower extremity amputations in persons with diabetes;2 and approximately 20% of persons with diabetes and plantar ulcers eventually undergo an ipsilateral lower extremity amputation.3 Early detection of foot problems and education of the person with diabetes with an "at-risk" foot, may be of benefit in preventing or minimizing adverse outcomes.5 In the United States, where 50% of non-traumatic lower extremity amputations occur in persons with diabetes, it has been suggested that up to 85% of the lower extremity amputations in this population could be averted by programmes for preventing and treating plantar ulcerations and through proper footcare education.5 Reports from primary and specialty care settings have noted sub-optimal consistency and thoroughness for foot examiniations.6 A coordinated team approach is the most beneficial to improve outcomes in patients with lower extremity complications due to diabetes.7 Unfortunately, persons with diabetes living outside major centres may have difficulty taking advantage of the team approach, especially aboriginal populations living in remote communities. Residence outside urban centres was found to be a significant risk factor for a poor outcome in persons with diabetes and foot ulcerations (Embil, unpublished). The one-year mortality rate after lower extremity amputation in the person with diabetes is 11% to 41% with the 3 and 5 year mortalities being 20% to 50% and 39% to 68% respectively.8

Few population-based and clinic-based studies demonstrate the incidence and prevalence of foot ulcerations and lower extremity amputations in persons with diabetes. Attempts have been made to try and summarize the global burden of foot ulcers and lower extremity amputations in persons with diabetes, however, the current state of knowledge with regards to diabetic foot disease is sub-optimal as this is not a reportable condition and is often deemed as low priority by many caregivers.9 Foot complications are a significant problem for the person with diabetes and for the health care system which they access.10 One study reported that the cost of care for a foot ulcer for a two year period after diagnosis approach $28,000.00 (United States)10, which is a significant financial burden to the patient and health care system, not to mention the emotional and psychological impact that this lesion has on the patient.

It is, therefore, contingent upon the health care provider to prevent the development of the initial ulceration and should an ulceration develop in the foot of the person with diabetes, to expedite its healing so as to prevent infection, and the possibility of a lower extremity amputation.

Management of the Diabetic Foot
Ideally, the people with diabetes should examine their feet daily and if vision is impaired, a care provider should provide this for them. They should examine for areas of erythema suggesting unrelieved pressure, for cracks between the digits which may act as a portal of entry for bacteria and for trauma to the nails which may lead to paronychia. The presence of blisters may suggest inadequately fitting footwear leading to shearing or ischemic necrosis of the skin. All surfaces of the foot should be evaluated and if any abnormality is detected, the person with diabetes should present for medical attention as soon as possible. Through simple techniques, the care provider can establish the neurovascular status of the person with diabetes lower extremity. It is critical to determine the presence, or absence of protective sensation as peripheral neuropathy puts the person with diabetes at high risk of foot ulceration. If pedal pulses are absent, non-invasive vascular studies would be prudent. The inability to appreciate the ten gram monofilament when applied for one second to ten sites on the soles, toepads and dorsum of the foot with sufficient pressure to cause the filament to bend, establishes the status of protective sensation.11,12,13 Once the status of protective sensation is established, the patient can be stratified according to "risk category" using the Carville approach.14 The Carville approach utilizes the presence of deformity, status of protective sensation and a history of foot ulceration in guiding the type of footwear and orthotics that may be necessary for the management of the person with an insensate foot. If the physical examination reveals Charcot changes, it is prudent to determine its stage and plan interventions accordingly. This approach is summarized in another article in this series.

If a foot ulceration is present, it is essential to determine its stage, specifically is it a superficial lesion involving only skin and soft tissue, or a more extensive lesion involving the deeper tissues to bone.15 The importance of establishing the stage of the lesion is that therapy will vary according to its depth and type of tissue involved.16 Non-infected superficial skin and soft tissue lesions can be managed with weight off loading and dressings which ensure moist wound healing. Lesions associated with dry gangrene are best managed with observation and dry dressings. A complete vascular evaluation is essential to ensure the adequacy of circulation and lesions in the feet of persons with diabetes will not heal if tissue profusion is inadequate. The involvement of bone complicates the therapeutic approach as osteomyelitis is best managed with either long term courses of oral antimicrobial therapy, or, alternatively parenteral therapy.15 Debridement of necrotic tissue is essential as is optimal weight off-loading.17 It is also important to ensure that the person with diabetes has basic footcare provided by someone skilled in the management of the foot of persons with diabetes. This is particularly important if the person with diabetes has retinopathy and is unable to adequately visualize their feet. These persons may also suffer from neuropathy and, therefore, will be unable to adequately appreciate trauma of the foot. It is important to ensure that the nails are adequately trimmed to prevent trauma of the surrounding toes from the nails. Callus paring is essential to remove any inappropriate pressure points from the soles of the feet.

In addition to these measures, footwear and orthotics are key to the prevention and healing of lesions in the foot of the person with diabetes. It is important to remember that it is not just the foot that is being managed, it is the whole patient and optimal glycemic control, nutrition, management of renal impairment and hygiene are critical for the best possible outcome.

Summary
From the previous discussion, it is clear that the complications of diabetes in the foot can have disastrous consequences. Early recognition of peripheral neuropathy and appropriate footwear and orthotics may prevent the onset of ulceration and may expedite their healing if they occur. The use of adjunctive measures such as weight off-loading and antimicrobial therapy in the face of infection are also critical. The importance of adequate circulation cannot be overstated.

References
  1. Reiber G.E., Vileikyte L., Boyko E.J., del Aguila M., Smith D.G., Lavery L.A., Boulton A.J.: Casual Pathways for Incident Lower extremity Ulcers in Patients with Diabetes from Two Settings. Diabetes Care 22(1): 157-162, 1999.
  2. Pecoraro R.E., Reiber G.E., Burgess E.M.: Pathways to Diabetic Limb Amputation. Basis for Prevention. Diabetes Care, 13 (5): 513-521, 1990.
  3. Reiber G.E.: The Epidemiology of Diabetic Foot Problems. Diabet Med, 13 (Suppl. 1): 6-11, 1996.
  4. Boyko E.J., Ahroni J.H., Smith D.G., Devignon D.: Increased Mortality Associated with Diabetic Foot Ulcer. Diabet Med, 13(11): 967-972, 1996.
  5. Edmonds M.E., van Acker K., Foster A.V.: Education and the Diabetic Foot. Diabet Med, 13 (Suppl 1): 61-64, 1996.
  6. Edelson G.W., Armstrong D.G., Lavery L.A., Caicco G.: The Acutely Infected Foot is Not Adequately Evaluated in an Inpatient Setting. Arch Intern Med, 156 (20): 2373-2378, 1996.
  7. Apelqvist J., Ragnarson-Tennvall G., Persson U., Larsson J.: Diabetic Foot Ulcers in a Multi-disciplinary Setting. An Economic Analysis of Primary Healing with Amputation. J Intern Med, 235 (5): 463-471, 1994.
  8. Most R.S., Sinnock P.: The Epidemiology of Lower extremity Amputations in Diabetic Individuals. Diabetes Care, 6 (1): 87-91, 1983.
  9. Boulton A.J.M.: The Diabetic Foot: A Global View. Diabetes Metab Res Rev, 16 (Suppl 1): S2-S5, 2000.
  10. Ramsey S.D., Newton K., Blough D., McCulloch D.K., Sandhu N., Reiber G.E., Wagner E.H.: Incidence, Outcomes and Costs of Foot Ulcers in Patients with Diabetes. Diabetes Care, 22 (3): 382-387, 1999.
  11. Foot Screening. Care of the Foot in Diabetes…The Carville Approach. Gillis W., Long Hansen's Disease Centre, Rehabilitation Branch. U.S. Government Printing Office: 1994 – 660-476/00017.
  12. Birke J.A., Sims D.S.: Plantar Sensory Threshold in the Ulcerated Foot. Leper Rev, 57: 261-267, 1996.
  13. De Heus-va Putten M.A., Schaper N.C., Bakker K.: The Clinical Examination of the Diabetic Foot in Daily Practice. Diabet Med, 13 (Suppl 1): 55-57, 1996.
  14. Duffy J.C., Patout C.A. Jr.: Management of the Insensitive Foot in Diabetes: Lessons Learned from Hansen's Disease. Mil Med, 155 (12): 575-579, 1990.
  15. Wagner F.W.Jr.: The Dysvascular Foot: A System for Diagnosis and Treatment. Foot Ankle, 2(2): 64-122, 1981.
  16. Embil J.M., Choudhri S.H., Germaine G., Imlah T., Duerksen F., Darcel M., Fong M., Koulack J., Gin A., Stern S., Simonsen J.N., Harding G.K.M., Nicolle L.E.: Community Intravenous Therapy Program and a Treatment Plan for Foot Infections in Persons with Diabetes: A Clinical Perspective. Can J Infect Dis, 11(Suppl A): 49A-56A, 2000.
  17. Steed D.L.: Foundations of Good Ulcer Care. Am J Surg, 176 (Suppl 2A): 20S-25S, 1998.
 
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