Diabetic Foot Problems
NICE guideline [NG19] Diabetic foot problems: prevention and management. Last updated: Oct 2019.
Background Information
Definition
Diabetic foot problems result from a combination of peripheral arterial disease (macrovascular) and diabetic neuropathy (microvascular).
Diabetic foot problems include:
- Diabetic foot ulcers
- Soft tissue infection
- Heel pressure sores (and other deep tissue destruction)
- Osteomyelitis
- Charcot arthropathy
Risk Assessment
Referral Criteria
Refer to the hospital immediately if any of the following:
- Gangrene (+/- ulceration)
- Ulceration with fever or any signs of sepsis
- Ulceration with limb ischaemia
- Concern of osteomyelitis or deep soft tissue infection
Assessment
Assess the patient's feet for:
- Neuropathy with a 10g monofilament to test for sensory function
- PAD with ABPI measurement
- Inspect for
- Ulceration
- Callus
- Infection and/or inflammation
- Deformity
- Gangrene
- Charcot arthropathy
Risk stratification:
| Risk category | Criteria |
|---|---|
| Low risk |
|
| Moderate risk | Any of the following:
|
| High risk | Any of the following:
|
Prevention
Low risk:
- Emphasise the importance of foot care importance
- Yearly foot assessment
Moderate or high risk:
- Emphasise the importance of foot care importance
- Refer to foot protection service
- Pressure redistribution device (to offload heel pressure)
- More frequent monitoring (every 3-6 months for moderate risk, every 1-2 months for high risk)
Diabetic Foot Ulcer
Definition
A diabetic foot ulcer is defined as a full-thickness wound located below the malleoli in a person with current or previously diagnosed diabetes.
Clinical Features
Presentation depends on the underlying cause and type.
Neuro-ischaemic ulcers are increasingly common, which has features of both types.
Neuropathic Ulcers
Typically located on pressure points (e.g. heel, metatarsal heads) [Ref]
- Punched-out appearance with well-defined regular edges
- Usually painless
- Abundant granulation tissue (if adequately perfused)
Ischaemic Ulcers
Typically located on pressure points (e.g. heel, metatarsal heads) [Ref]
- Punched-out appearance with well-defined regular edges
- VERY painful
- Accompanied by other features of PAD:
- Intermittent claudication / resting leg pain
- Diminished or absent lower limb pulse
- Cool skin
- Shiny skin and loss of hair
Complications
Complications include: [Ref]
- Infection (e.g. cellulitis, abscesses, necrotising fasciitis)
- Osteomyelitis
- Gangrene
- Lower extremity amputation – a major complication in ~20% of diabetic foot ulcers
Investigation and Diagnosis
Assess and document the following of a foot ulcer:
- Ulcer information (site, area, depth)
- Assess for any ischaemia / neuropathy / infection
Management
NICE recommends offering 1 or more of the following standard care (NICE did not make specific recommendations on when to offer, thus the relevant information is based on clinical practice):
| Care component | When to offer |
|---|---|
| Wound dressing | All patients with an ulcer |
| Offloading (pressure-redistributing devices) | Only for neuropathic, non-ischaemic, uninfected ulcers |
| Wound debridement (+/- negative wound pressure) | Only consider if there is extensive necrosis |
| Control of infection | Only offer antibiotics if there are signs of infection |
| Control of ischaemia | Only if there is ischaemia or PAD |
Consider dermal or skin substitutes as an adjunct to standard care, if healing has not progressed and on the advice of the multidisciplinary foot care service.
NICE says NOT to offer the following routinely (unless part of a clinical trial):
- Hyperbaric oxygen therapy
- Growth factor therapy
- Electrical stimulation therapy / autologous platelet-rich plasma gel, regenerative wound matrices, dalteparin
Diabetic Foot Infection
Definition
Diabetic foot infections vary depending on the extent and severity of the infection:
- Superficial infection
- Cellutlitis
- Abscess
- Osteomyelitis
- Wet gangrene
Aetiology
Diabetic foot infection usually occurs in the context of a diabetic foot ulcer.
Diabetic foot infections are most often polymicrobial: [Ref]
- Aerobic gram +ve cocci (esp. Staphylococcus aureus) are predominant in mild infections.
- A broader spectrum, including gram -ve bacilli and anaerobes, is involved in chronic or severe infections
Investigation and Diagnosis
If soft tissue infection is suspected:
- Soft tissue sample for microbiology
- Alternative: deep swab
If osteomyelitis is suspected:
- Probe-to-bone testing
- +ve test: probe directly contacts bone through the ulcer
- Suggests that the infection has extended from the soft tissue to the underlying bone
- X-ray
- MRI – confirmatory test
- Bone sample for microbiology
Management
Give oral antibiotics if the person can take oral medications
- IV antibiotic is necessary in severe infection
For exam purposes, it is sufficient to learn that flucloxacillin is the 1st line antibiotic used to treat mild diabetic infections (to cover Staphylococcus aureus).
In practice, the choice of antibiotic would be guided by the infectious disease unit and microbiology test results (e.g. culture and susceptibility),
Choice of antibiotics
| Scenario | Recommended antibiotics |
|---|---|
| Mild infection |
|
| Moderate / severe infection | 1st line:
Penicillin allergy:
|
| Suspected / confirmed Pseudomonas aeruginosa | Antibiotic choices:
|
| Suspected / confirmed MRSA | Antibiotics to be added:
|
Charcot Arthropathy
Definition
Charcot arthropathy is defined as a progressive, destructive joint disorder that occurs in the setting of peripheral neuropathy, most commonly due to diabetes mellitus.
Clinical Features
The tarsometatarsal joint (Lisfranc joint) is most commonly affected in Charcot arthropathy
Acute Charcot arthropathy:
- Redness / warmth / swelling / deformity (skin is typically intact)
- Pain is usually minimal or absent (due to neuropathy)
- Absence of deformity
Chronic stage:
- Painless bony deformities
- Rocker bottom foot deformity (collapsed midfoot)
Investigation and Diagnosis
- 1st line: X-ray (weight-bearing)
- 2nd line: MRI
Management
Offer a non-removable offloading device to all patients
Only consider surgical reconstruction for severe deformities or unstable foot