Diabetic Foot Ulcers: Nursing Study Guide —

Diabetic foot ulcers (DFUs) are a leading cause of non-traumatic lower extremity amputation. This guide reviews the pathophysiologic triad (neuropathy, ischemia, infection), Wagner staging, assessment, management, and the nursing priorities most often tested on the NCLEX.

Definition

Diabetic foot ulcers (DFUs) are open sores on the feet of diabetic patients, typically over pressure points such as the plantar surface. They are the leading cause of non-traumatic lower extremity amputations worldwide.

Risk Factors

Patient factors: long-standing diabetes (>10 years), poor glycemic control (HbA1c >7–8%), age >50
Foot-specific factors: peripheral neuropathy, peripheral arterial disease (PAD), foot deformities, callus formation
External factors: improper footwear, walking barefoot, poor foot hygiene
Other: previous foot ulcer or amputation, smoking, obesity, poor self-care

Peripheral neuropathy is the leading cause because loss of protective sensation allows minor trauma to go unnoticed and progress to ulceration.

Pathophysiology — The Triad

Peripheral neuropathy: loss of protective sensation; the patient cannot feel pain, pressure, or temperature, so minor trauma progresses to a full-thickness ulcer.
Peripheral arterial disease (PAD): impairs blood flow → tissue hypoxia, delayed healing, increased infection risk.
Infection: once the skin barrier is broken, bacteria enter; due to neuropathy and ischemia, infection can spread to bone (osteomyelitis) without obvious pain or systemic symptoms.

Neuropathy and ischemia are the initiating factors; infection is usually a consequence of ulceration.

Wagner Classification

Grade 0: No ulcer; high-risk foot → prevention focus
Grade 1: Superficial ulcer → may heal with offloading
Grade 2: Deep to tendon/capsule; no abscess → higher infection risk
Grade 3: Deep with abscess or osteomyelitis → requires antibiotics; may require bone debridement
Grade 4: Localized gangrene → high risk of amputation
Grade 5: Extensive gangrene → usually requires major amputation

Grade 0 requires preventive care. Grade 3 requires bone biopsy and prolonged antibiotics.

Clinical Presentation

Ulcers occur on the plantar foot or over pressure points (metatarsal heads, heel, toes).
Patients may have no pain due to neuropathy — even with deep infection.
Infection signs: purulent drainage, swelling, redness, warmth, foul odor.
Systemic symptoms (fever, chills) may be absent even with severe infection due to impaired immune response.

Neuropathic vs. Ischemic Ulcers

Neuropathic ulcer: painless, well-circumscribed, surrounded by callus, palpable pulses, warm skin.
Ischemic ulcer: pale, dry, minimal granulation, absent pulses.

Diagnostic Tests

10g monofilament: inability to feel at ≥1 site indicates loss of protective sensation.
Ankle-brachial index (ABI): <0.90 indicates PAD; may be falsely elevated in calcified vessels.
Wound culture: bone or deep tissue preferred over superficial swab.
Plain X-ray: may be normal early; detects osteomyelitis later.
MRI: best imaging for osteomyelitis and abscess.
Probe-to-bone test: if bone is felt, osteomyelitis is likely.

Do not use antibiotics for uninfected wounds.

Management

Offloading (Gold Standard)

Total contact casting (TCC) is the gold standard for neuropathic plantar ulcers — redistributes pressure and ensures compliance.

Wound Care

Cleanse with normal saline; avoid betadine or hydrogen peroxide.
Debride callus and necrotic tissue.
Maintain a moist wound environment with appropriate dressings (alginate, foam, hydrogel).

Infection Management

Empiric antibiotics chosen based on severity:

Mild (gram-positive cocci): oral cephalexin or dicloxacillin.
Moderate: oral amoxicillin-clavulanate, or clindamycin plus a fluoroquinolone.
Severe / limb-threatening: IV vancomycin plus piperacillin-tazobactam or a carbapenem.
Osteomyelitis: 6 weeks of antibiotics if infected bone remains; only 1 week after complete bone resection.
Do not use antibiotics for uninfected ulcers.

Revascularization (Ischemic Ulcers)

Indicated for PAD (ABI <0.90).
Options: angioplasty or bypass to restore pulsatile flow.

Complications

Osteomyelitis: probe-to-bone positive; requires bone biopsy.
Cellulitis: monitor for ascending erythema.
Abscess: requires incision & drainage; antibiotics alone are insufficient.
Gangrene: requires debridement or amputation.
Amputation: prevention is the goal.

Prevention and Foot Care Education

Inspect feet daily (use a mirror for soles).
Wash daily with lukewarm water and mild soap; test water temperature with the elbow.
Dry thoroughly, especially between toes.
Moisturize dry areas but not between toes.
Trim nails straight across.
Never walk barefoot.
Wear properly fitted shoes with a seamless toe box.
Maintain HbA1c <7% for tight glucose control.
Stop smoking.
Report any redness, blister, or sore immediately.

Nursing Assessment

Perform neurovascular assessment first.
Assess pedal pulses, capillary refill, sensation (10g monofilament), and ankle reflexes.
Assess wound: size, depth, color, exudate, odor.
Probe gently for underlying bone.
Assess for infection signs and systemic sepsis.

Nursing Interventions

Elevate limb only if no arterial insufficiency (elevation is contraindicated in ischemic ulcers).
Offload with total contact casting (TCC) or prescribed device.
Obtain culture before starting antibiotics; administer antibiotics as ordered.
Debride necrotic tissue.
Apply moist dressings.
Tight glucose control with insulin as needed.
Monitor for complications.
Educate patient on daily foot care and warning signs.

Common NCLEX Traps

No pain does not mean no pathology — neuropathy masks pain.
Neuropathic ulcers have pulses; ischemic ulcers do not.
Do not use antibiotics for uninfected ulcers.
A positive probe-to-bone = osteomyelitis until proven otherwise.
Total contact casting is the gold standard for offloading.
Elevation is contraindicated in ischemic ulcers.
Monitor for osteomyelitis if an ulcer fails to heal in 4–6 weeks.

Key takeaways

DFUs result from the triad of neuropathy, ischemia, and infection — neuropathy is the leading cause.
Wagner Grade 0 = prevention focus; Grade 3 = bone biopsy + prolonged antibiotics; Grades 4–5 often require amputation.
Total contact casting is the gold standard for offloading neuropathic plantar ulcers.
Neuropathic ulcers have pulses and are painless; ischemic ulcers lack pulses and require revascularization.
Do not treat uninfected ulcers with antibiotics; always culture before antibiotics when infection is suspected.
Nursing priorities: neurovascular assessment, offloading, wound care, glucose control, and prevention education.