Diabetic foot

Question 1

What is the diabetic foot?

Answer 1

Encompasses the conditions of diabetic foot ulcer (i.e full-thickness epithelial defect below/distal to the ankle) and diabetic foot infections (i.e. any soft tissue or bone infection occurring in the diabetic foot, including osteomyelitis)

Question 2

Aetiology of diabetic foot

Answer 2

1) Abnormal distribution of plantar pressures due to structural/ biomechanical abnormalities e.g. bunions, hammer or mallet toes, Charcot’s mid-foot deformities), impaired joint mobility, gait abnormalities and motor neuropathies.
2) Impaired protective mechanisms (dry skin, immune system abnormalities, peripheral artery disease)
3) Impaired recognition due to sensory neuropathy and/or visual impairments.
In most patients, epithelial ulceration results from repetitive trauma from the shoe contacting venous prominent skin surfaces of the foot during ambulation.

Question 3

Pathophysiology of diabetic foot

Answer 3

The longer the duration of a wound, the higher the risk of both soft tissue and bone infection.
Infection often spreads along anatomic planes in the foot and will often cause hyperglycaemia. Chronic hyperglycaemia may lead to sensory neuropathy and immune system dysfunction.

Question 4

Risk classification of diabetic foot.

Answer 4

High risk: Previous history of toe, partial foot or leg amputation.
Previous foot ulcer
Annual incidence of ulcers in this group is 50%.
Moderate risk: PAD with or without sensory neuropathy
Annual incidence (AI) is 14%
Low risk: sensory neuropathy. AI is 4.5%
Normal risk: None of the above. AI is 2%

Question 5

Diabetic foot classification

Answer 5

An active foot ulcer is scored using the SINBAD system.
Site: forefoot, midfoot and hindfoot.
Ischaemia: Pedal blood flow intact or clinical incidence of reduced pedal flow.
Neuropathy: Protective sensation intact or protective sensation lost.
Bacterial infection: none or present
Area: ulcer < 1cm or ulcer >1 cm
Depth: confined to skin or SC or ulcer reaching muscle, tendon or deeper.

Question 6

Initial evaluation of diabetic foot

Answer 6

1) Identifying the presence of any foot ulcers
2) Assessing for signs and symptoms of infections.
3) Any presence of sensory neuropathy
4) Documenting pedal pulses

Question 7

Investigations of diabetic foot

Answer 7

X-rays are ordered to screen for osteomyelitis, fractures, joint stability and other deformities.
Resting ABI is required in patients with suspected PAD.
MRI is best imaging test for the diagnosis of osteomyelitis.

Question 8

Differentials of diabetic foot

Answer 8

Venous leg ulcer
Gout
Acute charcot’s arthropathy

Question 9

Management of diabetic foot

Answer 9

3 key factors associated with limb loss include degree of tissue loss (wound severity), severity of ischaemia, and severity of foot infection.

• Mild infections can usually be treated in an outpatient setting.
• Wound care
• Offloading footwear- repetitive trauma is the most common cause of foot ulcers in diabetic patients
• Nutrition- malnutrition including sarcopenia
• Antibiotic therapy
• Surgery

Question 10

Key notes with diabetic foot

Answer 10

Patients with diabetic foot should have an eye screen.

Clindamycin is the antibiotic used for osteomyelitis as it can penetrate bones.