Summary

A Diabetic Foot Ulcer (DFU) is a full-thickness wound below the ankle in a patient with diabetes, resulting from the complex interplay of Neuropathy (loss of protective sensation), Ischaemia (Peripheral Arterial Disease), and Deformity (Motor neuropathy). It is the leading cause of non-traumatic lower limb amputation globally. Management requires a multidisciplinary "High Risk Foot Team" approach. The cornerstone of treatment is Offloading (Total Contact Cast), Infection Control, Revascularisation if ischaemic, and Excision of osteomyelitic bone. The risk of death following a major diabetic amputation is higher than that of many cancers (50% at 5 years).

Key Facts

• Lifetime Risk: 25% of diabetics will develop a foot ulcer.
• Amputation: 85% of amputations are preceded by a DFU.
• The Triad: Neuropathy + Deformity + Trauma = Ulcer.
• Osteomyelitis: If you can probe bone with a metal instrument, osteomyelitis is present until proven otherwise (Probe-to-Bone positive).
• Ischaemia: Often macrovascular ("Tibial vessel disease") with calcification (Monckeberg's medial sclerosis).
• Gold Standard: Total Contact Cast (TCC) for offloading neuropathic ulcers.

Clinical Pearls

"Probe to Bone": Use a sterile metal probe. If you hit something hard and gritty at the base of the ulcer, the Positive Predictive Value for Osteomyelitis is >90%.

"Assume Sepsis": Diabetics are often immunosuppressed. They may have a foot full of pus (deep plantar abscess) but have NO fever, NO tachycardia, and normal CRP. Pain or unexplained hyperglycaemia might be the only sign.

"Don't Trust the ABPI": In diabetics, vessel walls are calcified (stiff pipes). The cuff cannot compress them, giving falsely elevated readings (>1.3). You MUST use Toe Pressures (TBPI) or Waveforms.

"It's not the sugar, it's the shoe": Most ulcers are caused by repetitive trauma from ill-fitting shoewear on a numb, deformed foot.

The "3-Minute Foot Exam"

1. Look: Skin breaks? Callus? Deformity (Claw toes)? Colour?
2. Feel: Temperature (Hot = Charcot or Infection; Cold = Ischaemia). Pulses (DP/PT).
3. Test:
   • Monofilament (10g): Test 10 sites. Failure to feel = Loss of Protective Sensation (LOPS).
   • Probe: Sterile probe into any ulcer.

Wagner Classification (Old but common)

• Grade 0: Intact skin (High risk).
• Grade 1: Superficial ulcer.
• Grade 2: Deep ulcer (to tendon/bone).
• Grade 3: Deep ulcer + Abscess/Osteomyelitis.
• Grade 4: Forefoot Gangrene.
• Grade 5: Whole foot Gangrene.

University of Texas (Modern)

Matrix of Depth (0-3) vs Infection/Ischaemia (A-D). Better prognostic value.

          DIABETIC FOOT ULCER
                   ↓
┌─────────────────────────────────────────┐
│        ASSESS: VIP (Vascular,           │
│        Infection, Pressure)             │
└─────────────────────────────────────────┘
        ↙          ↓            ↘
   ISCHAEMIC?    INFECTED?     NEUROPATHIC?
      │            │              │
      ↓            ↓              ↓
┌───────────┐ ┌───────────┐ ┌────────────────┐
│ RE-VASC   │ │ ANTIBIOTIC│ │ OFFLOADING     │
│ - Angio   │ │ - Debride │ │ - TCC (Cast)   │
│ - Bypass  │ │ - Drain   │ │ - Reduct. Shoe │
│           │ │ - Amputat │ │ - Callus cut   │
└───────────┘ └───────────┘ └────────────────┘

1. Infection Management (Source Control)

• "Time is Tissue".
• Deep Abscess: Needs urgent surgical drainage (Incision & Drainage).
• Osteomyelitis:
  • Medical: 6 weeks IV/Oral antibiotics (high bone penetration e.g., Doxycycline, Ciprofloxacin, Rifampicin).
  • Surgical: Resection of infected bone (e.g., digit amputation, metatarsal head resection).

2. Vascular Management

• If pulses absent or TBPI <0.5 -> Urgent Vascular Referral.
• Angioplasty (Balloon) is commonest intervention for tibial vessels.

3. Pressure Management (Offloading)

• Total Contact Cast (TCC): Gold standard. Forces compliance. Distributes pressure over whole leg. 90% healing rate in 6-8 weeks.
• Removable Walker (Moonboot): Patient can take it off (Poor compliance).
• Felt Padding: Temporary.

Often the most effective way to restore function and remove infection.

1. Ray Amputation

• Removing a toe and its metatarsal.
• Indication: Osteomyelitis of MTPJ or Metatarsal Head.
• Leaves a narrower functional foot.

2. Transmetatarsal Amputation (TMA)

• Removing all toes and metatarsal heads.
• Indication: Gangrene of multiple toes / forefoot.
• Preserves the heel/ankle for walking. Requires Achilles Lengthening to prevent equinus.

3. Major Amputation (BKA/AKA)

• Below Knee (Transtibial): Preserves knee joint. Energy expenditure for walking is much lower than AKA.
• Above Knee (Transfemoral): For extensive gangrene. Rehabilitation is harder.

A separate topic, but linked.

• Definition: Acute inflammatory destruction of bone/joints in neuropathic foot.
• Presentation: Resembles Cellulitis (Red, Hot, Swollen).
• Distinction: Elevate the leg. Charcot redness fades; Cellulitis stays red.
• Treatment: STRICT IMMOBILISATION (Cast) until cooling occurs.

Key Guidelines

1. IWGDF Guidelines (International Working Group on the Diabetic Foot): The global bible.
2. NICE NG19: Diabetic foot problems.

Key Trials

1. Eurodiale Study: Large cohort. Showed infection + ischaemia = worst prognosis.
2. TCC Evidence: Multiple RCTs confirm TCC is superior to removable devices for healing.

What is a Diabetic Foot Ulcer?

It is a wound on the foot of someone with diabetes. Because diabetes damages the nerves, you might not feel pain when you get a blister or stone in your shoe. This turns into a deep sore.

Why is it dangerous?

Because the blood supply is often poor, these wounds heal very slowly. Germs (bacteria) can get in and spread to the bone. If not treated quickly, this can lead to gangrene and amputation.

What is the treatment?

1. Take the pressure off: You may need a special cast or boot. You cannot walk on the wound.
2. Clean it: A specialist will remove dead skin (callus).
3. Blood flow: We check if you need a procedure to open blocked arteries.
4. Antibiotics: If there is infection.

How do I prevent it?

• Check your feet EVERY DAY (use a mirror for the bottom).
• Never walk barefoot.
• Get your feet checked by a podiatrist regularly.
• Keep your blood sugar controlled.