Pathophysiology
Diabetic foot disease usually results from the interaction of:
- peripheral neuropathy with loss of protective sensation
- peripheral arterial disease
- repetitive pressure and deformity
- impaired wound healing
- infection
Motor neuropathy may produce clawing and altered pressure distribution. Autonomic neuropathy contributes to dry skin and fissuring.
Assessment
History
Ask about:
- duration and control of diabetes
- previous ulceration or amputation
- neuropathic symptoms
- claudication or rest pain
- footwear
- smoking
- renal disease and other vascular risk factors
Examination
Assess:
- ulcer site, size, depth and surrounding tissue
- callus and deformity
- warmth, swelling and erythema
- pedal pulses and capillary refill
- protective sensation with a 10 g monofilament
- vibration and proprioception when required
Infection
Infection is a clinical diagnosis. Features include erythema, warmth, swelling, tenderness or purulent discharge.
Deep tissue obtained after debridement is preferable to a superficial swab when microbiological sampling is required.
Osteomyelitis
Suspect osteomyelitis with:
- a deep or chronic ulcer
- exposed bone or a positive probe-to-bone test
- persistent inflammatory markers
- suggestive radiographic change
MRI is useful when the diagnosis or extent is uncertain.
Vascular assessment
Peripheral arterial disease must be actively sought. ABI can be misleadingly high in diabetes because of arterial calcification; toe pressures or other vascular studies may be more useful when perfusion is uncertain.
Management
Ulcer care
- pressure off-loading
- debridement of devitalised tissue
- appropriate dressings
- optimisation of glycaemic control and nutrition
- treatment of infection when present
Vascular disease
Refer for vascular assessment and revascularisation when perfusion is inadequate for healing.
Surgery
Surgery may be required for:
- drainage or debridement of infection
- osteomyelitis not controlled by conservative measures
- correction of deformity causing recurrent ulceration
- non-salvageable infection or ischaemia
Charcot neuroarthropathy
An acutely warm, swollen neuropathic foot with little pain should raise concern for Charcot neuroarthropathy. Early off-loading and immobilisation are essential.
References
- Orthobullets. Diabetic Foot Ulcers.
- Orthobullets. Diabetic Charcot Neuropathy.