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The diabetic foot ulcer - management and outcomes

Impaired perfusion Infection Extent and depth Condition of the ulcer Site Sensation and pain Oedema General characteristics and co-morbidity Metabolic control Psychosocial factors Recurrent ulceration Healthcare organization Expected outcomes of effective treatment Further reading A summary of the management of a diabetic foot ulcer Heel necrosis Total contact cast

  • In diabetes, healing of foot ulcers is limited by multiple factors and therefore requires a multifactorial approach.
  • Control of infection, treatment of vascular disease, pressure relief and wound management are essential components of the multifactorial treatment of foot ulcers.
  • Type, site and cause of the ulcer must be considered in choosing treatment strategies.
  • Topical wound management is adjunctive to systematic and surgical treatment.
  • Continuity of care and lifelong observation of the diabetic foot at risk are essential both in management and prevention of foot ulcers.

Given the multifactorial origin of diabetic foot ulcers, a systematic approach to management is essential. Where necessary, the following aspects should be assessed and treated in each patient.

Impaired perfusion

Peripheral arterial disease (PAD) is one of the main determinants of outcome in diabetic foot ulcers. In a recent European study, almost 60% of the patients had (neuro-)ischaemic foot ulcers. The evaluation and treatment of PAD has been described in this document, and a short summary is given in this chapter as part of the complete management programme. The majority of people with (neuro-)ischaemic diabetic foot ulcers do not have symptoms of claudication or rest pain; but if present, claudication and rest pain are strongly related to the probability of amputation. Testing for the presence or absence of PAD is the first step. Once a diagnosis is likely, the severity of ischaemia should be quantified using non-invasive vascular assessment. Based on these evaluations, revascularization should always be considered if PAD is present.

Infection

Infection is also a main determinant of outcome, and is present in more than 50% of patients at initial presentation to a foot care team. In particular, the combination of infection and PAD is a major risk factor for lower-leg amputation. This combination should be considered as a medical emergency. As described in the chapter on infection, if they are not treated as emergency cases, many patients with deep foot infections have few local or systematic symptoms and have a high probability for amputation. Once the diagnosis has been made, prompt anti-microbial treatment has to be instituted. In people with a deep foot infection, surgery is frequently needed: the infected compartment is opened to ensure adequate drainage, devitalized tissue is removed, and, in order to improve healing, repeated debridement is frequently required.

Extent and depth

The amount of tissue loss and the type of tissue involved is strongly related to outcome; large or deep ulcers will need more time to heal. Moreover, ulcers with exposed tendons or bone are vulnerable to infection and are probably associated with delayed healing. In superficial ulcers, the emphasis will be on removal of callus, necrotic tissue, and stimulation of granulation and epithelialization. In a deep-ulcers, stimulation of matrix formation also has to be considered.

Condition of the ulcer

In many cases, diabetic foot ulcers fail to heal quickly and become chronic wounds - as described in the chapter on wound healing. Healing is inhibited by factors that are both intrinsic and extrinsic to the wound and its biology. Intrinsic factors include: defective leucocyte function, abnormal production of growth factors and extra-cellular matrix, reduced fibroblast activity, and excess production of wound proteases. From the clinical perspective, the ulcer should be evaluated with regard to necrosis, slough, the periwound area (callosities/maceration), granulation and signs of inflammation. Initial sharp debridement is necessary to determine whether the ulcer extends into deeper or surrounding tissues. This is particularly important in the presence of infection. In case of severe ischaemia without infection, there is less call for sharp debridement unless a revascularization procedure has been performed. An adequate amount of viable soft tissue has to be present to allow debridement to be performed without exposing bone.

Other principles of wound care include: controlling excessive exudate, and keeping the wound surface appropriately moist. Once the wound bed is clean, strategies to improve matrix formation, granulation and epithelialization can be initiated - as discussed in the chapter on wound healing.

Site

A precipitating trauma can often be found in patients with a foot ulcer. An ulcer caused by tight- or ill-fitting shoes or an acute mechanical trauma are usually localized on the digits or dorsum of the foot. An ulcer caused by elevated mechanical stress (mal perforans, stress ulcer) is usually localized to metatarsal heads, while decubitus ulcers are usually localized on the heel. Relief of mechanical stress is mandatory for healing, and the type (neuropathic, neuro-ischaemic, ischaemic) and site of the ulcer will determine the off- loading strategy. Most studies on off-loading were performed in patients with neuropathic plantar forefoot ulcers. These studies showed that reduction of plantar pressure is probably essential in the healing of such ulcers. For further details, the reader is referred to the chapter on footwear and off-loading.

Sensation and pain

Although many people with diabetic foot ulcers feel pain, the loss of protective sensation is one of the principal factors in the pathogenesis of most foot ulcers - as described in the chapter on pathophysiology. Also, in the treatment phase, this loss of warning symptoms can negatively affect the healing process: for the patient, it is difficult to understand the rationale behind, and thus comply with, the prescribed off-loading without some form of simple and appropriate explanation.

Only 50% of people with diabetes-related gangrene have rest pain. However, the presence of pain is strongly related to the probability of amputation. People with diabetic foot ulcers can have pain or discomfort of various aetiology. Pain can be caused by factors such as painful neuropathy, infection, ischaemic rest pain, wound handling, etc. Therefore, the underlying pathology should be evaluated systematically. Once its cause is determined, pain can be treated adequately. Anxiety should also be taken into account when treating pain.

Oedema

The outcome of a foot ulcer is related to oedema. Oedema is often multifactorial in origin, with congestive heart failure, nephropathy, previous venous thrombosis and neuropathic/ hydrostatic oedema the most important causes. Treatment of oedema must focus on the predisposing cause.

General characteristics and co-morbidity

Whether or not the type of diabetes influences the outcome of foot ulcers is not known, especially since the vast majority of foot ulcers and amputations are seen in people with type 2 diabetes. In clinical studies corrected for age and sex, the duration of diabetes has been found not to be related to the outcome of a foot ulcer. Age, however, has an important influence on outcome of foot ulcers, and is also related to the probability of major amputation. Nevertheless, older patients can also heal primarily. A prospective study found that 43% of people with diabetes above 80 years of age with a foot ulcer healed primarily.

The key factor in foot ulcer management is to recognize that the lesion is frequently sign of multi-organ disease. Diabetic nephropathy defined as macro-albuminuria has been identified as a risk factor both for foot ulcers and lower-extremity amputation. Proteinuria is also considered to be a marker of widespread vascular disease in people with diabetes. Furthermore, patients with end-stage renal disease have higher amputation rates. Therefore, foot lesions in these people should be treated as aggressively as possible. Congestive heart failure, ischaemic heart disease, and cerebrovascular disease have also been related to amputation and level of amputation. Therefore, the presence of any co- morbidity must be considered in the treatment of a diabetic foot ulcer; such conditions should be treated aggressively.

Metabolic control

In some studies, HbA1c and fluctuating blood glucose levels have been considered risk factors for non-traumatic lower-extremity amputation. Short-term metabolic control has been related to wound healing in case reports and experimental studies of wound healing. Glycaemic control has been suggested to be related to levels of growth factors, fibroblast activity, changes in collagen metabolism, and haemorrhagic disturbances. All these factors have - together with non-enzymatic glycation - been suggested to influence the short-term outcome of foot ulcers. Hyperglycaemia has also been suggested to impair migration of leukocytes and interfere with phagocytosis and bactericidal activity. In experimental studies, the abnormalities listed above improved when normoglycaemia was achieved. The controversy, however, relates to whether these abnormalities arise as a consequence of metabolic factors or impaired circulation. Nonetheless, experts advise that optimal metabolic control and optimal nutritional status are desirable to improve wound healing.

Psychosocial factors

When choosing a treatment strategy socio-economic factors (such as access to healthcare) and adherence to treatment should be taken into account. In some case-controlled studies, people with diabetes with a foot ulcer and a lower-extremity amputation have shown increased levels of non-adherence. Due to complications such as neuropathy and visual impairment - as described in the chapter on psychosocial factors - it is difficult to distinguish true 'neglect' from a lack of awareness of the potential danger of a foot ulcer. A syndrome of 'wilful self-neglect' has been described in people with diabetes and foot ulcers. In one study of patients with foot ulcers, delays in treatment were attributable to patients in 12% of cases and to professionals in 21% of cases. This is further emphasized by findings on the referral for multifactorial treatment of patients with a foot ulcer only after the failure of an initial treatment strategy (usually dressing and/or antibiotics), or deterioration of the wound.

Recurrent ulceration

Although healing can be achieved in the majority of patients, many have recurrent foot ulceration. In all patients, the cause of ulceration should be meticulously sought. In several studies, the relapse rate of people with neuropathic and/or neuro-ischaemic ulcers varies between 17-81% within 2 years after healing. Therefore, once an ulcer has occurred, the patient will need to participate in a preventive foot care programme with continuous surveillance.

Healthcare organization

In order to improve outcomes for people with diabetic foot ulcers, effective communication and collaboration is required between the many professionals involved in diabetic foot care. Patients should receive education on the need to contact their healthcare provider as soon as an ulcer is seen. Subsequently, the patient should be promptly referred for systematic evaluation and treatment to a healthcare provider with experience in the field of diabetic foot care. Preferably, this healthcare worker should be a member of a multidisciplinary foot team.

Several studies suggest that a 49-85% reduction in amputations can be achieved in countries with specialized diabetic foot centres through a comprehensive programme involving treatment of patients with foot ulcers by a multidisciplinary team, together with patient and staff education in foot care and footwear. In addition, in two studies in which the efficacy of a multidisciplinary approach was compared with standard treatment, the multidisciplinary approach was associated with improved healing rates and lower amputation rates. The organization of such a foot care team is described in the chapter on organizing the foot care clinic.

Expected outcomes of effective treatment

As described above, healing rates in centres treating diabetic foot ulcers are influenced by a variety of factors, some of which are related to the patients - such as PAD, infection or end-stage renal disease - and others to the characteristics of local healthcare organization. However, based on recent clinical trials in patients with neuropathic foot ulcers, a healing rate of 50-70% within 20 weeks can be expected. It should be noted that in most of these trials off-loading was not standardized. In large cohort studies of diabetic foot ulcers of mixed origin (neuropathic and neuro-ischaemic), a major amputation rate of 5-10%, with a mortality rate of 10-15%, was reported.

Further reading

Edmonds M, Blundell MP, Morris ME, Thomas EM, Cotton LT, Watkins PJ. Improved survival of the diabetic foot: the role of a specialized foot clinic. Q J Med 1986; 60: 763-71.

Apelqvist J, Larsson J, Agardh CD. Long-term prognosis for diabetic patients with foot ulcers. J Intern Med 1993; 233: 485-91.

McCabe CJ, Stevenson RC, Dolan AM. Evaluation of a diabetic foot screening and protection programme. Diabet Med 1998; 15: 80-4.

Apelqvist J. Wound healing in diabetes: outcome and costs. Clin Pod Med Surg 1998; 15: 21-40. Amstrong DG, Lavery LA, Harkless LB. Validation of a diabetic wound classification system. The contribution of depth, infection, and ischemia to risk of amputation. Diabetes Care 1998; 21: 855-9.

Dargis V, Pantelejeva O, Jonushaite A, Vileikyte L, Boulton AJM. Benefits of a multidisciplinary approach in the management of diabetic foot ulceration in Lithuania. Diabetes Care 1999; 22: 1428-31.

Margolis DJ, Kantor J, Santanna J, Strom BL, Berlin JA. Risk factors for delayed healing of neuropathic diabetic foot ulcers: a pooled analysis. Arch Dermatol 2000; 136: 1531-5.

Armstrong DG, Nguyen HC. Improvement in healing with aggressive edema reduction in persons with diabetes. Arch Surg 2000; 135: 1405-9.

Oyibo SO, Jude EB, Tarawneh I, Nguyen HC, Armstrong DG, Harkless LB, Boulton AJ. The effects of ulcer size and site, patient's age, sex and type and duration of diabetes on the outcome of diabetic foot ulcers. Diabet Med 2001; 18: 133-8.

Margolis DJ, Allen-Taylor L, Hoffstad O, Berlin JA. Diabetic neuropathic foot ulcers: the association of wound size, wound duration and wound grade on healing. Diabetes Care 2002; 25: 1835-9.

Moulik PK, Mtonga R, Gill GV. Amputation and mortality in new-onset diabetic foot ulcers stratified by etiology. Diabetes Care 2003; 26: 491-4.

Connor H, Mahdi OZ. Repetitive ulceration in neuropathic patients. Diabetes Metab Res Rev 2004; 20 (Suppl 1) S23-S28.

Jeffcoate WJ, Chipchase SY, Ince P, Game FL. Assessing the outcome of the management of diabetic foot ulcers using ulcer-related and person-related measures. Diabetes Care 2006; 29: 1784-7.

Beckert S, Witte M, Wicke C, Konigsrainer A, Coerper S. A new wound-based severity score for diabetic foot ulcers. Diabetes Care 2006 ; 29: 988-92.

Prompers L, Huijberts M, Apelqvist J, Jude E, Piaggesi A, Bakker K, Edmonds M, Holstein P, Jirkovska A, Mauricio D, Ragnarson Tennvall G, Reike H, Spraul M, Uccioli L, Urbancic V, Van Acker K, van Baal J, van Merode F, Schaper N. High prevalence of ischaemia, infection and serious comorbidity in patients with diabetic foot disease in Europe. Baseline results from the Eurodiale study. Diabetologia 2007; 50: 18-25.

A summary of the management of a diabetic foot ulcer
GoalStrategy
• Improve circulation

Non-invasive vascular testing

Percutaneous transluminal angioplasty (PTA)

Vascular surgery

• Treat edema

Intermittent external compression

Diuretics

• Pain control

Analgesic agents

Relieve anxiety

• Treat infection

Antibiotics

- Oral

- Parenteral

Culture, biopsy

X-ray, CT, Bone-scan, MRI

• Improve metabolic control

Sharp blood glucose regulation

Malnutrition

• Non-weight bearing

Therapeutic footwear

Insoles / ortheses

Contact casting / Scotch cast boot

Crutches

Wheelchair / Bed-rest

• Topical treatment

Debridement

Dressings

Topical agents

Skin grafting

• Foot surgery

Incision / drainage

Corrective surgery

Amputation

• General condition

Cardiovascular treatment

Treat retinopathy / nephropathy

Treat malnutrition

Cessation of smoking

• Setting

Patient / staff education

Compliance

Support / follow-up

Multidisciplinary


Heel necrosis
Different stages of a necrotic (pressure) heel ulcer


Several devices to protect the heel to prevent the development of a pressure ulculcer.


Total contact cast
Different steps in encasing the foot in a total contact cast which is not removable, to deflect pressure from the ulcerated papart.




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