Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are chronic wounds occurring in individuals with diabetes mellitus, resulting from the interaction of neuropathy, peripheral arterial disease, and repetitive trauma. They represent the most common and costly complication of diabetes, with devastating consequences for patients and healthcare systems.

Epidemiology and Burden

Global Impact (Zhang, Ann Med 2016, PMID 27585063; Armstrong, JAMA 2023, PMID 37395769):

• Pooled global prevalence among people with diabetes: 6.3% (95% CI 5.4-7.3%), with wide regional variation (North America ~13%, Oceania ~3%)
• Approximately 18.6 million people develop a diabetic foot ulcer worldwide each year
• Approximately 80% of diabetes-related lower-limb amputations are preceded by a foot ulcer
• Lifetime risk of foot ulceration in diabetes is commonly cited at roughly 15-25%

Outcomes and Prognosis (Armstrong, JAMA 2023, PMID 37395769; NEJM 2017, PMID 28614678):

• Only ~30-40% of ulcers heal at 12 weeks under usual care
• Recurrence: ~42% at 1 year, ~60% at 3 years, ~65% at 5 years despite initial healing
• About 20% of moderate-to-severe infections lead to lower-extremity amputation
• ~30% 5-year mortality after a diabetic foot ulcer; greater than 70% after a major amputation (worse than most cancers)

Risk Factors

History

Key Questions:

• Duration of diabetes and glycemic control (HbA1c)
• Previous ulcers or amputations (strongest risk factor)
• Claudication, rest pain (vascular symptoms)
• Sensory symptoms: numbness, tingling, burning (neuropathy)
• Trauma or precipitating event (often forgotten by patient due to neuropathy)
• Footwear: what do they wear at home? (many patients wear inappropriate slippers)
• Self-care ability: can they see their feet? Can they reach to inspect?

Physical Examination

Differential Diagnosis

Not every wound on a diabetic foot is a simple neuropathic ulcer. Distinguishing the dominant mechanism (and excluding mimics) changes management entirely.

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Algorithm

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Multidisciplinary Team Approach

Evidence: Multidisciplinary foot care teams reduce amputation rates by 49-85% compared to standard care.

Essential Team Members:

• Diabetologist or endocrinologist (glycemic control)
• Podiatrist (wound care, debridement, orthotics)
• Vascular surgeon (revascularization)
• Orthopaedic or plastic surgeon (reconstruction, amputation)
• Infectious disease specialist (complex infections, osteomyelitis)
• Orthotist (custom footwear, AFOs)
• Diabetes nurse educator (self-care, prevention)

The 5 Pillars of DFU Management

1. Offloading (CRITICAL) 2. Debridement 3. Infection Control 4. Vascular Assessment and Revascularization 5. Metabolic and Wound Environment Optimization

Total Contact Casting (Gold Standard)

Instant Total Contact Cast (iTCC Walker)

Alternative to TCC:

• Removable cam walker rendered non-removable with cohesive bandage or fiberglass
• Prefabricated device with custom foam padding
• Similar efficacy to TCC (75-90% healing) IF rendered non-removable
• Allows wound inspection without cast removal

Advantage: Can be temporarily removed for wound care by healthcare provider Disadvantage: If patient can remove it (non-compliance), efficacy drops to 30-50%

Other Offloading Devices

Key Principle: Non-removable greater than removable. Studies show patients wear removable devices only 20-30% of the time when alone at home, despite reporting "full compliance."

Surgical Offloading

Sharp Debridement (Essential)

Evidence: Weekly sharp debridement associated with 2-3x higher healing rates vs episodic debridement.

Wound Dressing Principles

Goal: Maintain moist wound environment (improves epithelialization by 50% vs dry wounds)

Dressing Selection by Wound Characteristics:

Dressing Change Frequency:

• Infected wounds: daily
• Clean granulating: every 3-7 days
• Goal: minimize wound disruption

Advanced Wound Therapies

IDSA/IWGDF Infection Criteria

Diagnosis of Infection (NOT just colonization):

• Purulence (pus), OR
• 2 or more inflammatory signs:
  • Local warmth
  • Erythema (greater than 2 cm from wound edge = moderate infection)
  • Lymphangitis
  • Edema
  • Pain or tenderness (unusual in neuropathic patients - ominous if present)

Severity Grading:

Antibiotic Therapy

Principles:

• Treat infection, NOT colonization - all chronic wounds are colonized
• Empiric therapy based on severity and previous cultures
• Narrow to culture results after 48-72 hours
• Duration: 1-2 weeks for soft tissue; 4-6 weeks for osteomyelitis

Empiric Regimens (IDSA Guidelines):

Mild Infection (outpatient, oral):

• Cephalexin 500mg QID, OR
• Amoxicillin-clavulanate 875mg BID, OR
• Clindamycin 300mg TID (if penicillin allergy)
• Duration: 1-2 weeks

Moderate Infection (inpatient or close outpatient):

• Ampicillin-sulbactam 3g IV Q6H, OR
• Ceftriaxone 2g IV daily PLUS metronidazole 500mg IV Q8H, OR
• Ertapenem 1g IV daily (if MRSA risk, add vancomycin)

Severe Infection (inpatient, broad-spectrum):

• Vancomycin 15mg/kg IV Q12H (trough 15-20) PLUS
  • Piperacillin-tazobactam 4.5g IV Q6H, OR
  • Meropenem 1g IV Q8H
• Consider antifungal if prolonged antibiotics or immunosuppressed

MRSA Coverage (add if risk factors: previous MRSA, healthcare exposure, failed cephalosporin):

• Vancomycin, OR
• Linezolid 600mg PO/IV BID, OR
• Daptomycin 6mg/kg IV daily

Osteomyelitis Management

Vascular assessment and revascularisation is listed as the fourth pillar of management and appears as a branch in the algorithm, but it deserves to be developed because perfusion is frequently the rate-limiting step: roughly half of patients with a diabetic foot ulcer have peripheral arterial disease, and an ischaemic or neuroischaemic ulcer will not heal with offloading, debridement and antibiotics alone until inline blood flow to the foot is restored. Inadequate perfusion is the dominant driver of non-healing and of major amputation.

When to suspect ischaemia and investigate

Use the perfusion findings already covered: absent pedal pulses, a cool/hairless foot, ABI less than 0.9 (or non-compressible greater than 1.3 from medial calcification — fall back to toe-brachial index, toe pressure or TcPO2), monophasic Doppler waveforms, and TcPO2 less than 30 mmHg. Any ulcer that fails to progress despite optimal wound care, or any clinically ischaemic/neuroischaemic ulcer, warrants prompt vascular imaging (arterial duplex, then CT or MR angiography, or catheter angiography) and a vascular surgery referral. Healing-potential thresholds worth targeting after intervention are TcPO2 greater than 40 mmHg and restoration of at least one patent tibial/pedal vessel to the foot.

Staging limb threat

Beyond Wagner/Texas/PEDIS, the SVS WIfI classification (Wound, Ischaemia, foot Infection) grades each of those three axes (0–3) to estimate the threat to the limb, the likely benefit of revascularisation and the risk of major amputation. It is the vascular-surgery counterpart to the ulcer-depth systems and is increasingly used to decide who needs urgent perfusion restoration.

Choosing the revascularisation strategy

Both restore perfusion; the choice is individualised to patient fitness, lesion anatomy and conduit availability. The landmark randomised trials informing this debate are BASIL and BEST-CLI: the overall message is that a durable surgical bypass with a good-quality autologous (great saphenous) vein tends to give the best limb-salvage and the fewest reinterventions in patients fit for surgery, whereas an endovascular-first strategy is favoured for higher-risk patients, suitable focal lesions, or when no adequate vein is available. In the foot itself, the angiosome concept (Attinger) holds that directing flow to the specific source artery supplying the angiosome containing the ulcer (direct/angiosome-targeted revascularisation) may improve healing and limb salvage; where the target vessel cannot be reached, indirect revascularisation through collaterals can still heal many wounds.

Sequencing with infection and the salvage-vs-amputation decision

In the infected ischaemic foot, urgent source control comes first — drain pus and debride necrotic/infected tissue without delay — then revascularise promptly; do not let angiography planning hold up control of spreading sepsis. If perfusion cannot be restored, or the foot is not functionally salvageable (extensive tissue loss, non-ambulatory patient, unreconstructable disease), a primary amputation at a healing level may give a better, faster functional outcome than repeated failed salvage attempts (see Surgical Management).

Definition and Pathophysiology

Charcot neuroarthropathy (Charcot foot) is a progressive destructive arthropathy of the foot and ankle in patients with peripheral neuropathy, resulting in bone and joint destruction, fractures, and deformity.

Eichenholtz Classification (Stages)

Clinical Patterns

Management

Risk Stratification and Surveillance

IWGDF Risk Categories and Surveillance Frequency:

• Category 0 (no neuropathy): annual screening
• Category 1 (neuropathy alone): 6-12 month screening
• Category 2 (neuropathy + PAD or deformity): 3-6 month screening
• Category 3 (previous ulcer or amputation): 1-3 month screening

Patient Education (Self-Care)

Footwear Prescription

Home Foot-Temperature (Dermal Thermometry) Monitoring

After protective sensation is lost, the patient can no longer feel the inflammation that precedes ulceration — but it can be measured. Localised inflammation from a high-pressure "hotspot," early infection or acute Charcot raises the local skin temperature days before the skin breaks down. Daily home measurement of plantar skin temperature at matched sites on both feet detects this hotspot and turns an invisible warning into an actionable one.

Glycemic Control

Evidence: Each 1% reduction in HbA1c associated with 25% reduction in microvascular complications (including neuropathy)

Target: HbA1c less than 7% (individualize based on patient factors)

Multidisciplinary Prevention Programs

Components of Successful Programs:

• Regular screening (based on risk category)
• Patient education (structured programs)
• Therapeutic footwear provision
• Podiatry for nail and callus care
• Prompt treatment of pre-ulcerative lesions

Evidence: Comprehensive prevention programs reduce:

• Ulcer incidence by 50-60%
• Amputation rates by 49-85%
• Recurrent ulcers by 35-50%

Global Epidemiology

A systematic review and meta-analysis (Zhang, Ann Med 2016; PMID 27585063) pooled a global diabetic foot ulcer prevalence of 6.3% among people with diabetes, with striking regional variation. The contemporary JAMA review (Armstrong, 2023; PMID 37395769) estimates ~18.6 million new ulcers worldwide each year.

Sex (higher in men), diabetes duration, smoking, hypertension and retinopathy are consistent risk associations (Zhang 2016).

Major Guidelines, Side by Side

The dominant international standard is the IWGDF (International Working Group on the Diabetic Foot), updated as a guideline suite; IDSA governs infection; NICE NG19 (UK) and AAOS/ADA statements broadly align. Where the headline recommendations differ, the differences are modest and mostly emphasis.

Registry & System-Level Evidence

Diabetic foot disease is tracked through diabetes and amputation registries rather than implant registries. National audit data (e.g. the UK National Diabetes Foot Care Audit) consistently show that earlier specialist multidisciplinary assessment is associated with better healing and fewer major amputations, and that organised high-risk foot services reduce major amputation rates — concordant with the pooled estimate that multidisciplinary care lowers major amputation versus usual care (OR 0.40, 95% CI 0.32-0.51; Armstrong 2023, PMID 37395769).

Global Practice Variation

• High-resource settings: ready access to TCC, vascular imaging, endovascular revascularisation, NPWT, advanced dressings and dedicated multidisciplinary foot clinics; emphasis on limb salvage and remission care.
• Limited-resource settings: later presentation, higher proportion of severe infection and major amputation, limited revascularisation; offloading may rely on improvised felted-foam/half-shoe techniques and sandals rather than TCC. Prevention and education yield the greatest marginal benefit where surgical and vascular services are scarce.
• Across all settings the principles are invariant: offload, debride, control infection, restore perfusion, optimise metabolism, and place the healed foot in lifelong remission care.