People with diabetes are at increased risk of peripheral vascular disease and neuropathy, as well as having a higher risk of developing infections and decreased ability to clear infections. Therefore, people with diabetes are prone to frequent and often severe foot problems and a relatively high risk of infection, gangrene and amputation.
Motor, sensory and autonomic fibres may all be affected in people with diabetes mellitus.
- Because of sensory deficits, there are no protective symptoms guarding against pressure and heat and so trauma can initiate the development of a leg ulcer.
- Absence of pain contributes to the development of Charcot foot (see 'Charcot foot', below), which further impairs the ability to sustain pressure.
- Motor fibre abnormalities lead to undue physical stress, the development of further anatomical deformities (arched foot, clawing of toes), and contribute to the development of infection.
- When infection complicates a foot ulcer, the combination can be limb-threatening or life-threatening.
- Detection and surveillance of diabetic neuropathy are an essential routine part of a diabetic annual review.
- The results of cross-sectional community surveys in the UK showed that 5.3% (type 2) and 7.4% (types 1 and 2 combined) of people with diabetes had a history of active or previous foot ulcer.
- An annual incidence of 2.2% was found in a large community survey in the UK, and up to 7.2% in patients with neuropathy.
- The incidence of major amputation is between 0.5 and 5.0 per 1,000 people with diabetes.
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- Risk factors for foot ulceration include peripheral arterial disease, peripheral neuropathy, previous amputation, previous ulceration, presence of callus, joint deformity, problems with vision and/or mobility, and male sex.
- Risk factors for peripheral arterial disease include smoking, hypertension and hypercholesterolaemia.
- People with diabetes develop foot ulcers because of neuropathy, ischaemia or both.
- The initiating injury may be from acute mechanical or thermal trauma or from repetitively or continuously applied mechanical stress.
- Peripheral neuropathy in people with diabetes results in abnormal forces being applied to the foot, which diabetic ischaemia renders the skin less able to withstand.
- Other complications contributing to the onset of ulceration include poor vision, limited joint mobility, and the consequences of cardiovascular and cerebrovascular disease.
- However, the most common precipitant is accidental trauma, especially from ill-fitting footwear.
- Once the skin is broken, many processes contribute to defective healing, including bacterial infection, tissue ischaemia, continuing trauma, and poor management.
- Infection can be divided into superficial and local, soft tissue and spreading (cellulitis), and osteomyelitis. Typically, more than one organism is involved, including Gram-positive, Gram-negative, aerobic, and anaerobic species. Staphylococcus aureus is the most common pathogen in osteomyelitis.
- Diabetic foot ulcers are usually painless, punched-out ulcers in areas of thick callus ± superadded infection, pus, oedema, erythema, crepitus, malodour.
- Neuro-ischaemic ulcers tend to occur on the margins of the foot, and neuropathic ulcers tend to occur on the plantar surface of the foot.
- Neuropathic foot tends to be warm with dry skin, bounding pulses, distended veins, reduced sensation and callus around the ulcer.
- Neuro-ischaemic foot tends to be cool, pink with atrophic skin and absent pulses; the foot may be painful and there is little callus.
A Charcot foot is a neuro-arthropathic process with osteoporosis, fracture, acute inflammation and disorganisation of foot architecture. Suspected Charcot neuro-arthropathy of the foot is an emergency and should be referred immediately to a multidisciplinary foot team.
- The Charcot foot is characterised by bone and joint degeneration which can lead to a devastating deformity. It usually presents as a hot swollen foot after minor trauma.
- Slight trauma triggers fracture of a weakened bone, which increases the load on adjacent bones, leading to gross destruction. The process is self-limiting but the persisting deformity greatly increases the risk of secondary ulceration.
- Plain X-ray may be normal but a bone scan may show a hot spot.
- Damage and developing deformity should be limited by immobilising the foot in a cast, and realignment arthrodesis of the hind foot can sometime prevent amputation.
Management of the diabetic foot includes:
- Education, including the importance of routine preventative podiatry care, and appropriate footwear. The person should check their feet every day and report any sores or cuts that do not heal, puffiness, swelling, and skin that feels hot to the touch.
- Control of glucose, blood pressure and cholesterol; smoking cessation and weight control.
- Risk assessment.
- Mechanical foot interventions to prevent ulceration.
- Antibiotics to manage and prevent infection.
- Management of peripheral arterial disease, including bypass surgery.
- Wound management, including keeping the wound dry and debridement of dead tissue.
- Methods to help self-examination/monitoring; daily examination of feet for problems (colour change, swelling, breaks in the skin, pain or numbness).
- The importance of well-fitting and comfortable footwear; regular checking of footwear for areas that will cause friction or other problems; seeking help from a healthcare professional if footwear causes difficulties or problems; wearing specialist footwear if it has been prescribed/supplied.
- Hygiene (daily washing and careful drying); moisturising areas of dry skin.
- Nail care.
- Dangers associated with practices such as skin removal; dangers associated with over-the-counter preparations for foot problems.
- When to seek advice from a healthcare professional: if any colour change, swelling, breaks in the skin, corns or calluses, pain or numbness are found, or if self-care and monitoring are not possible or difficult (eg because of reduced mobility).
- Possible consequences of neglecting the feet: potential complications and the benefits of prevention and prompt detection and treatment.
- For people at increased, or high, risk of foot ulcers; in addition to the above:
- If neuropathy is present, extra care and vigilance are needed and additional precautions to keep the feet protected.
- The patient should not walk barefoot.
- Seeking help to deal with potential burning of numb feet: check bath temperatures, avoid hot water bottles, electric blankets, foot spas and sitting too close to fires.
- Additional advice about foot care on holiday: not wearing new shoes, planning adequate rest periods to avoid additional stress on feet, the importance of walking up and down aisles when travelling by air, use of sun block on feet, having a first aid kit and covering any sore places with a sterile dressing, seeking help if problems develop
- For people with foot ulcers:
- The importance of early detection and prompt treatment.
- Appropriate resting of foot/leg.
- Reporting any changes in the ulcer or surrounding skin, discharge, foot smells, swelling or generally feeling unwell and/or poor glucose control.
Foot assessment as part of routine diabetic care
- Effective care involves a partnership between patients and professionals, and all decision making should be shared.
- Organise a recall system. Arrange recall and annual review as part of ongoing care.
- As part of annual review, trained personnel should examine patients' feet to detect risk factors for ulceration. All people with diabetes should be regularly screened to assess their risk of developing a foot ulcer.
- Examination of patients' feet should include:
- Testing of foot sensation, using a 10 g monofilament or vibration.
- Palpation of foot pulses.
- Inspection of any foot deformity and footwear.
- Classify foot risk as (if the patient has had any previous foot ulcer or deformity or skin changes, manage as high-risk): low current risk, increased risk, high-risk and ulcerated foot.
- Risk stratification: the recent Scottish Intercollegiate Guidelines Network (SIGN) guideline classifies risk as:
- Low: no risk factors present, eg no loss of sensation, no signs of peripheral arterial disease and no other risk factors.
- Moderate: one risk factor present, eg loss of sensation or signs of peripheral arterial disease without callus or deformity.
- High: previous ulceration or amputation or more than one risk factor present, eg loss of sensation or signs of peripheral arterial disease with callus or deformity.
- Active: presence of active ulceration, spreading infection, critical ischaemia, gangrene or unexplained hot, red, swollen foot with or without the presence of pain.
- Care of people at low current risk of foot ulcers (normal sensation, palpable pulses):
- Agree a management plan including foot care education with each person.
- Care of people at increased risk of foot ulcers (neuropathy or absent pulses or other risk factor):
- Arrange for regular review, 3-6 monthly, by a foot protection team.
- At each review:
- Inspect the patient's feet.
- Consider the need for vascular assessment.
- Evaluate the patient's footwear.
- Enhance foot care education.
- Care of people at high risk of foot ulcers (neuropathy or absent pulses plus deformity or skin changes or any previous ulcer):
- Arrange for frequent review (1-3 monthly) by a foot protection team.
- At each review:
- Inspect the patient's feet.
- Consider the need for vascular assessment.
- Evaluate and ensure the appropriate provision of:
- Intensified foot care education.
- Specialist footwear and insoles.
- Skin and nail care.
- Ensure special arrangements for those people with disabilities or immobility.
Foot care emergency (new ulceration, swelling, discolouration)
- Don't delay: deterioration in an ulcer is more likely if assessment and management are delayed.
- Take swabs and treat with prompt antibiotics according to local protocols - usually staphylococcal coverage, plus wider spectrum, anaerobes, or streptococcal until sensitivities are known.
- Admit the patient for systemic antibiotic therapy for significant cellulitis or bone infection. Adjust antimicrobial therapy according to culture results when available.
- If not admitted as an emergency, refer to a multidisciplinary foot care team within 24 hours. A well-organised multidisciplinary approach providing continuity of care between primary and secondary care is essential.
- The core specialist foot care team should usually consist of a specialist podiatrist, specialist orthotists, nurses with training in the dressing of diabetic foot wounds and diabetologists with expertise in diabetic lower-limb complications.
- Expect that team, as a minimum, to:
- Investigate and treat vascular insufficiency. Patients with clinically significant peripheral vascular disease and limb ischaemia should be assessed by a vascular surgeon to determine the need for angioplasty, stenting, or femoro-distal bypass. Since ischaemia can delay healing, revascularisation needs to be considered at an early stage.
- Initiate and supervise wound management.
- Involve surgeons early:
- The degree of peripheral vascular disease, the patient's general health and the patient's age, lifestyle and views will determine whether local excision (debridement) and drainage, vascular reconstruction and/or amputation (and how much) will be appropriate.
- Surgery to heal ulcers and prevent recurrence can include tenotomy, tendon lengthening, reconstruction, or removal of bony prominences. However, these procedures may result in secondary ulceration and other complications.
- Absolute indications for surgery include:
- Abscess or deep infection.
- Spreading anaerobic infection.
- Severe ischaemia or rest pain.
- Septic arthritis.
- Amputation is generally reserved for:
- Uncontrolled pain (secondary to vascular disease).
- Debilitating, long-term, non-healing ulceration.
- A useless and disabling infected or Charcot foot.
- Ensure an effective means of distributing foot pressures (alleviation of the mechanical load on ulcers), eg specialist footwear, orthotics and casts.
- Neuropathic ulcers typically heal in six weeks with total contact casting, because it effectively relieves pressure at the ulcer site and enforces patient compliance.
- The success of other approaches to off-loading also depends on patients' adherence to the effectiveness of pressure relief.
Management of painful neuropathy
See also separate article Neuropathic Pain and its Management.
- Provide emotional support for the depressing and disabling nature of the condition.
- Consider initially:
- Bed foot cradles for night-time problems.
- Simple analgesia taken in advance of diurnal symptoms.
- Contact dressings.
- Consider therapeutic trials of:
- Tricyclic antidepressants (TCAs) should be used as first-line therapy in painful diabetic neuropathy.
- Carbamazepine is also effective.
- Gabapentin is also recommended in painful diabetic neuropathy and is associated with fewer side-effects than TCAs and older anticonvulsants.
- Topical capsaicin should be considered for the relief of localised neuropathic pain.
- Foot ulcers in people with diabetes have a high risk of necessitating amputation.
- Ulcer recurrence rates are high, but appropriate education for patients, regular surveillance, the provision of post-healing footwear and regular foot care can reduce rates of re-ulceration.
- Survival after amputation is poor. Perioperative mortality is 10-15% in the UK.
Further reading & references
- Neuropathic pain - pharmacological management, NICE Clinical Guideline (March 2010)
- Diabetic foot problems - inpatient management, NICE Clinical Guideline (March 2011)
- Diabetes UK
- Jeffcoate WJ, Harding KG; Diabetic foot ulcers. Lancet. 2003 May 3;361(9368):1545-51.
- Management of diabetes, Scottish Intercollegiate Guidelines Network - SIGN (March 2010)
- Edmonds ME; Progress in care of the diabetic foot. Lancet. 1999 Jul 24;354(9175):270-2.
- Type 2 diabetes: Prevention and management of foot problems, NICE Clinical Guideline (January 2004)
- National Diabetes Support Team, Diabetic Foot Guide (April 2006)
- Cavanagh PR, Lipsky BA, Bradbury AW, et al; Treatment for diabetic foot ulcers. Lancet. 2005 Nov 12;366(9498):1725-35.
|Original Author: Dr Colin Tidy||Current Version: Dr Colin Tidy|
|Last Checked: 22/06/2011||Document ID: 2848 Version: 24||© EMIS|
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