The Diabetic Foot Ulcer

FOCUS | CLINICAL

Rebecca Reardon, Dominic Simring, DIABETIC FOOT ULCERS are a significant foot; consequently, many standard Boyoung Kim, James Mortensen, cause of morbidity and mortality in shoes are unsuitable for patients with Deepak Williams, Anthony Leslie the Western world and can be complex diabetes. Sensory neuropathy reduces the and costly.1 The risk of a patient with patient’s sensory awareness and thus the Background diabetes developing a foot ulcer across patient fails to recognise that the shoe is 6,7 Diabetic foot ulcers are associated with their lifetime has been estimated to be ill-fitting, resulting in pressure injuries. significant morbidity and mortality and 19–34%.2 In addition, the incidence Lazzarini, Fernando and Netten can subsequently lead to hospitalisation rates for ulcer recurrence remain high: (2019) have published an acronym – and lower limb amputation if not 40% within one year after ulcer healing, MADADORE – to assist clinicians to recognised and treated in a timely manner. and 65% within five years.2 An annual remember the recommended diabetic foot 8 Objective diabetic foot assessment and optimal ulcer management principles (Figure 1). The aim of this article is to review the management by a multidisciplinary team The aim of this article is to increase current evidence for preventing and including general practitioners (GPs) awareness of diabetic foot ulcers among managing diabetic foot ulcers, with the and podiatrists can reduce infection- health professionals and to provide aim to increase clinicians’ confidence in related morbidities, the need for and structured guidance in preventing and assessing and treating these complex medical presentations. duration of hospitalisation and the managing patients with diabetic foot incidence of major limb amputation.3,4 ulcer. This is in line with Australian and Discussion A systematic review has shown that international guidelines on diabetic foot All patients with diabetes should have initiation of a multidisciplinary team disease.9,10 an annual foot review by a general care model resulted in a reduction in practitioner or podiatrist. A three- monthly foot review is recommended for major amputations in 94% (31 of 33) 5 any patient with a history of a diabetic of studies. There are many factors Risk factors foot infection. Assessment involves involved in the development of foot The risk factors for diabetic foot ulcers identification of risk factors including ulcers in patients with diabetes. The include: peripheral neuropathy and peripheral two most important risk factors are • diabetic neuropathy – this is the most vascular disease, and examination of peripheral neuropathy (sensory, motor common complication of diabetes, ulceration if present. It is essential to and autonomic) and peripheral vascular affecting up to 50% of patients with identify patients with diabetes who are 11 ‘at risk’ of ulceration, assess for any disease (PVD). Trauma also plays a type 1 and type 2 diabetes. Peripheral early signs of skin breakdown, initiate significant part in the development of neuropathy can be sensory, motor or appropriate management to prevent ulceration; in Western countries, the most autonomic. Sensory neuropathy is progression and refer the patient common cause of trauma is ill-fitting usually insidious in nature and can if indicated. shoes.6,7 Motor neuropathy results in clinically present as positive symptoms structural changes in the shape of the such as burning, tingling or paraesthesia

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in a stocking-and-glove distribution, sweating and dry skin that can develop by their GP or podiatrist. Clinical or as negative symptoms such as skin cracks and fissures, increasing examination of the diabetic foot is numbness.11,12 Motor neuropathy the risk of developing diabetic foot essential for identification of the risk typically presents as wasting of the ulceration.1,14 factors that lead to ulceration. Patients intrinsic muscles of the foot, resulting • PVD – patients with diabetes are more with risk factors require more frequent in clawing of the toes and changes to susceptible to distal lower limb arterial examination – every 1–6 months, the architecture of the mid-foot, and disease, typically affecting small depending on severity.4 The presence subsequently in pressure redistribution arteries below the knee and within the of these risk factors will dictate further over the metatarsal heads. Autonomic foot, resulting in ischaemia. investigations, management and neuropathy can contribute to foot In summary, neuropathy allows referral for non-GP specialist care. Ulcer ulceration through increased skin ulceration to develop after unrecognised description should include site, size, atrophy, dry or overly moist skin, hair trauma, whereas poor blood supply depth and discharge of wound. Assessing loss to the legs and ridged/ brittle (ischaemia) inhibits wound healing. the neuropathic and vascular status of toenails.12 Patients with diabetes who These are compounded by diabetic the foot should follow. have moderate-to-severe sensory loss immunosuppression, resulting in an Ischaemic wounds commonly occur are seven times more likely to develop increased likelihood of severe infections. in the cool, poorly perfused foot, often their first foot ulcer when compared located in the areas around the lateral with patients with diabetes who do not fifth metatarsal head and medial first have neuropathy.13 Other consequences Examination metatarsal head. Identifying the degree of neuropathy include poor balance All patients with diabetes should have of ischaemia is of great importance in due to loss of proprioception, reduced a foot examination performed annually wound evaluation. Careful palpation of the pedal pulses (dorsalis pedis and posterior tibial arteries) is necessary. In approximately 12% of the population, Metabolic/Medication the dorsalis pedis artery is absent or Optimise associated medical conditions, such as hyperglycaemia, markedly reduced in size, so a pulse may 11 M hyperlipidaemia and hypertension. not be palpable. A cool foot with no palpable pedal pulses warrants further Assessment investigation with non-invasive arterial A Examine diabetic foot ulcer and grade according to PEDIS Doppler ultrasonography studies of the classification (perfusion, extent [size], depth, infection and sensation). lower limb. Other methods of assessing peripheral perfusion may not be entirely Debridement reliable in patients with diabetes. The D Surgically debride diabetic foot ulcer with necrotic or unhealthy tissue. ankle brachial pressure index (ABI) measurement may be falsely elevated for Antibiotics patients with diabetes because of arterial Treat patient with diabetic foot ulcer with appropriate antibiotics on calcification. Toe pressure measurements A the basis of the severity of the infection. are more reliable than ABI measurements in this patient group (Figure 2), although Dressing the latest literature indicates that their Perform frequent wound care with adequate dressings. D utility is limited.15 An absolute toe pressure exceeding 30 mmHg is required Offloading for normal wound healing; however, for Advise patient with diabetic foot ulcer to wear appropriate offloading patients with diabetes, an ABI <0.7 or toe O shoes to reduce plantar pressure. pressure <30–40 mmHg in the presence Referral of a wound warrants a vascular surgical Facilitate early referral to a multidisciplinary diabetic foot team for consultation.10,12,16 These are measures of R optimal management of diabetic foot ulcer. poor arterial perfusion and are associated with impaired wound healing.12,16 Education Asymptomatic PVD (no claudication or Education on foot self-care should be provided to patients with E diabetic foot ulcer or associated risk factors. ulceration) in a person with diabetes can be managed by observation. Neuropathic wounds commonly Figure 1. The MADADORE acronym8 occur in the warm but insensate foot in pressure-bearing areas, often surrounded

by callus tissue. Peripheral neuropathy Classification of diabetic scanning with IV contrast is an acceptable can be identified on inspection during a foot infections alternative when investigating for neurological examination of the lower Identification and classification of osteomyelitis.12 Detailing the patient’s limb. Toenails that are abnormally diabetic foot infections is important, as diabetic and neuropathic status, the thickened, yellow in colour and patients with severe infections require exact anatomical location of the ulcer crumbling can be evidence of sensory immediate hospitalisation, intravenous and whether the ulcer probes to bone will and autonomic neuropathy, or both.12 (IV) broad-spectrum antibiotics and result in a more detailed assessment/ Dry and scaly skin with hyperkeratoses surgical consultation. Ischaemia of the radiological report of the area in question on the toes or balls of the feet, or very foot may increase the severity of all grades when requesting imaging. moist skin are also signs of autonomic of infection and warrants prompt referral neuropathy.12 Visible channels to a vascular surgical specialist. between the metatarsals are caused Treatment by denervation of the lumbricals and If there is adequate arterial supply to interossei, resulting in muscle wasting Investigations the foot, treatment of any infection with (Figure 3). Hammer toes are also due Superficial swabs are often contaminated appropriate antibiotics, debridement of to lumbrical denervation (Figure 4).12 with skin flora and are of little value. Deep necrotic tissue and pressure offloading, Loss of Achilles reflex is indicative of tissue samples (biopsy, ulcer curettage or diabetic foot ulcers should heal. Offloading advanced peripheral neuropathy.12 aspiration) are superior in diagnosing ulcer management (removal of pressure from the Assessment with a tuning fork and light infection.19 wound) is crucial for plantar neuropathic and coarse touch will reveal any sensory ulcers, and patient education is key in neuropathy.12 successful implementation. Correct identification of an infected Diagnostic imaging Infection occurs as a result of diabetic foot ulcer is critical because, Plain radiography is the most common ulceration and is not a cause thereof.1 if present with co-existing PVD, it may first-line radiological investigation in an Generally speaking, most diabetic foot lead to amputation.1,12 Any visible bone acute presentation of a diabetic foot ulcer infections are polymicrobial and require or bone palpable on probing can confirm to assess for underlying osteomyelitis. broad-spectrum antibiotic treatment. a clinical diagnosis of osteomyelitis.17 Magnetic resonance imaging is the Management of mild-to-moderate diabetic Early identification and referral to a best imaging modality to diagnose foot infections involves the use of oral podiatrist for regular assessments and osteomyelitis as it is more sensitive and broad-spectrum antibiotics initially, which customised pressure-offloading footwear specific;12,20 however, it can be of limited are then narrowed following results of is key in the management of neuropathic availability, is expensive and may not be cultured deep tissue.1 Severe infections diabetic ulcers.18 readily available. Computed tomography including cellulitis and osteomyelitis

Figure 2. Toe pressure measurement device22 Figure 3. Deep channels between the metatarsals are indicative of lumbrical muscle wasting from denervation

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arequire IV antibiotics initially, with urgent Neuropathic ulcers without infection debridement of necrotic tissue. Antibiotics are best treated by removing the callus should be continued until the clinical signs tissue around the ulcer and effective of infection have resolved.1 Optimisation pressure offloading. It is recommended of glycaemic control is very important, as that after the wound has healed, offloading hyperglycaemia impairs wound healing.1 should continue for another four weeks There are many diabetic foot ulcer to enable scar tissue formation to scoring systems available. The PEDIS tolerate future weight bearing. Life-long (perfusion, extent, depth, infection and maintenance of appropriate footwear sensation) classification for diabetic foot and patient education is vital to the ulcers (Tables 1 and 2) was created by ongoing prevention of ulceration. Key the International Working Group of the recommendations include: wearing shoes Diabetic Foot to help clinicians assess risk or at all times to avoid incidental trauma, prognosis for a person with diabetes and an performing a nightly foot self-check for Figure 4. Hammer toe active foot ulcer and to help communicate early ulceration or pressure areas, and within the multidisciplinary team.19,21 getting feet measured prior to purchasing shoes to ensure the correct fit. Once a patient has had any kind of diabetic foot Table 1. Clinical classification of a diabetic foot infection21 infection, they have a higher risk of future Infection PEDIS ulceration and should be reviewed by a Clinical manifestations of infection severity grade podiatrist regularly. • Wound without any evidence of purulence or inflammation Uninfected 1 • Wound associated with ≥2 signs suggestive of inflammation Mild 2 Referral (purulence, erythema, pain, tenderness, warmth or induration) The best approach to diabetic foot ulcers • Extent of erythema limited to ≤2 cm around the ulcer involves a multidisciplinary team that • Superficial infection without evidence of systemic toxicity or local can comprise but not be limited to: GPs, complications endocrinologists, podiatrists, wound care • Wound associated with infection as described above but Moderate 3 nurses, vascular surgeons and infectious without signs of systemic illness diseases specialists.5 If there is a wound • Meets ≥1 of the following criteria: erythema >2 cm, lymphangitic care clinic available, referral to this service streaking, spread beneath the superficial fascia, deep-tissue is also advised for ongoing specialist abscess, gangrene and involvement of muscle, tendon, joint or bone wound management. • Wound associated with infection Severe 4 • Evidence of systemic toxicity or metabolic instability (eg fever, chills, tachycardia, hypotension, confusion, vomiting, leucocytosis, Conclusion acidosis, severe hyperglycaemia or azotaemia) An annual foot review is necessary for all PEDIS, perfusion, extent, depth, infection and sensation patients with diabetes, with more frequent review (1–3-monthly) recommended for any patient with a history of diabetic foot Table 2. The PEDIS classification system19 infection. The main aim is to identify patients ‘at risk’ of ulceration, assess Grade Perfusion Extent Depth Infection Sensation for any early signs of skin breakdown, 1 No PVD Skin intact Skin intact None No loss initiate appropriate management to prevent progression and refer the patient 2 PVD; no CLI <1 cm Superficial Surface Loss if indicated. 3 CLI 1–3 cm Fascia, Abscess, muscle, fasciitis, Authors tendon septic arthritis Rebecca Reardon MBBS, Unaccredited Surgical Registrar, Lismore Base Hospital, NSW 4 >3 cm Bone or joint Systemic Dominic Simring FRACS (Vasc), Head of inflammatory Department, Vascular Surgery, Lismore Base response Hospital, NSW syndrome Boyoung Kim MBBS, Junior Medical Officer, General Surgery, Lismore Base Hospital, NSW CLI, critical limb ischaemia; PEDIS, perfusion, extent, depth, infection and sensation; PVD, peripheral James Mortensen MBBS, ACRRM GP Registrar, vascular disease Riverside Family Practice, Casino, NSW

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