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Gen Surgery > The diabetic foot > Flashcards

The diabetic foot Flashcards

1
Q

What is the diabetic foot?

A

Defined as a group of syndromes in which neuropathy, ischaemia and infection lead to tissue breakdown, resulting in morbidity and amputation

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2
Q

What is the lifetime and annual risk that a diabetic patient will acquire foot lesions

A
  • Lifetime: 15-25 %

- Annual incidence: 1.0- 4.0 %

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3
Q

Risk factors for ulceration

A

Systemic contributions:

  • uncontrolled hyperglycemia
  • duration of diabetes
  • peripheral vascular disease
  • blindness or visual loss
  • chronic renal disease
  • older age

Local issues:

  • peripheral neuropathy
  • structural foot deformity
  • trauma and improper fitted shoes
  • callus
  • history of prior ulcer or amputation
  • prolonged elevated pressure
  • limited joint mobility
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4
Q

What is the aetiology of diabetic foot ulcers

A
  • Critical triad of: peripheral sensory neuropathy, trauma and deformity
  • other risk factors: Ischaemia, callus, oedema
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5
Q

What are the two theories of the pathophysiology of neuropathy in diabetes

A
  • Vascular decreased blood supply to the nerves –> hypoxia
  • Blood glucose levels in nerve are directly proportional to that of blood –> glucose transformed into fructose and sorbitol –> biochemical and functional abnormalities
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6
Q

How does sensory neuropathy present in a diabetic

A
  • Symmetrical sensory loss in a glove and stocking distribution
  • Patient can present with numbness, paraesthesia or burning under the feet
  • Ulcers commonly occur with minor wounds that the patient is not aware of
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7
Q

How does autonomic neuropathy present?

A
  • Loss of sweating –> dry foot –> fissures and cracks, which predisposes to ulceration
  • Changes in the microcirculation –> increased peripheral blood flow –> AV shunting –> ischaemia of deeper tissues
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8
Q

Which vessels are usually affected by PVD in a diabetic

A

tibial and peroneal vessels between the ankle and the knee, the distal vessels are usually spared

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9
Q

What is arterial disease due to in diabetics?

A

Atherosclerosis and medial sclerosis

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10
Q

Diabetics have decreased ability to develop collaterals and atheroscleosis is 20 x more common. Why don’t they develop claudication/ rest pain?

A

Neuropathy

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11
Q

How does oedema predispose to ulcer formation

A

-It impairs cutaneous circulation and healing

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12
Q

Why are diabetics at an increased risk for infection?

A
  • Impaired immune system
  • Impaired humoral immunity
  • impaired PMN function
  • Loss of protective skin barrier
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13
Q

Connective tissue changes in diabetes leads to limited joint mobility which leads to…

A
  • stiffness of the joints of the foot

- abnormal gait

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14
Q

Which joints does diabetic Charcot’s osteoarthropathy affect?

A
  • midtarsal (60%)
  • metatarsophalangeal
  • ankle
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15
Q

What are the two major theories regarding the aetiology of neuro- arthropathy?

A
  • neurotraumatic

- neurovascular

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16
Q

Which four factors are essential for arthropathy to develop?

A
  • peripheral neuropathy
  • unrecognized injury
  • increased local blood flow
  • repetitive stress in injured structures
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17
Q

What is the differential for neuro-arthropathy?

A

Gout, cellulitis, osteomyelitis

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18
Q

Describe the classic neuropathic foot

A

Warm, dry, insensitive, dilated veins, good pulses, pes cavus, clawed toes and hyperkeratosis under the forefoot and heel

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19
Q

At what frequency is vibration sense tested

A

128 HZ

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20
Q

What non invasive vascular tests can you perform

A
  • ankle brachial index
  • arterial duplex
  • toe pressure measurements
  • transcutaneous oxygen measurements
21
Q

What is abnormal ABI, toe pressure measurement and transcutaneous oxygen measurements

A

Abi: <0.45 is limb threatening
Toe pressure: <45 systolic is abnormal
Transcutaneous oxygen: < 30 mmHg suggests wound healing is less likely

22
Q

What are foot deformities associated with diabetic foot

A
  • skin cracks, fissures, calluses
  • claw toes, hammer toes
  • rocker bottom feet
  • pes cavus
  • hallux valgus and hallux rigidis
  • Charcot’s foot
  • fixed flexion deformity of the PIP joints
  • flexion deformity of PIP joints
23
Q

Which are the normal weight bearing areas in the foot, how does it change with diabetes

A

Normally the metatarsal heads and heels are the greatest weight bearing area. In diabetics there is loss of protection of the foot pads and reduced ankle joint dorsiflexion. This causes early lifting of the heels resulting in premature loading of the forefoot and increased duration of pressure

24
Q

Which two ways can foot pressure be measured

A
  1. Podotrack

2. Optical pedograph

25
Q

what is the definition of a limb threatening infection

A

Generally, limb threatening infections can be defined by cellulitis extending beyond 2 cm from the ulcer perimeter as well as deep abcess, osteomyelitis or critical ischaemia

26
Q

Which organisms usually cause infection in a diabetic foot

A

polymicrobial infections usually predominate:

  • Gram positive: staphylococcus, streptococcus, enterococcus
  • Gram negative: E. coli, pseudomonas, Klebsiella, proteus
  • Anaerobes: Bacteroides, clostridium perfringens, peptostreptococcus
27
Q

What may be the only sign of infection in a diabetic patient

A

Unexplained hyperglycemia

28
Q

What are the reasons to do radiological evaluation of a diabetic foot?

A
  • Monitor bone and joint changes
  • Detect subcutaneous air
  • Detect foreign bodies
  • Detect osteomyelitis
  • XR are not sensitive for acute infections of bone (latent period of 10- 14 days; needs 50 % bone loss)
29
Q

If the xray is negative but there is strong suspicion of osteomyelitis, what other investigations can be done?

A
  • Bone scan

- Ct scan

30
Q

What is the Wagner classification of a diabetic foot?

A
  • Grade 0: foot at risk, no ulceration
  • Grade 1: Superficial diabetic ulcer, no infection
  • Grade2: extension of ulcer to deeper tissue
  • Grade 3: Deep ulcer with abcess or osteomyelitis
  • Grade 4: localized gangrene
  • Grade 5: extensive gangrene
31
Q

What is the University of Texas Wound classification System of Diabetic Foot ulcers

A
  • Grade I-A: non-infected, non-ischaemic superficial ulceration
  • Grade I-B: infected, non-ischaemic superficial ulceration
  • Grade I-C: Ischaemic, non-infected superficial ulceration
  • Grade I-D: Ischaemic and infected superficial ulceration
32
Q

What are the categories for a patient with a foot at risk? What is their follow-up?

A

0: no sensory neuropathy- once a year follow-up
1: Sensory neuropathy- twice a year follow-up
2: signs of neuropathy and PAD and or foot deformities; once every three months
3: previous ulcers- once a month

33
Q

What is the treatment of an established ulcer

A
  • Rest and elevation should be instituted at the first presentation
  • Relief of pressure by ‘off-loading’
  • mainstay of treatment is debridement of all necrotic tissue, callus and fibrous tissue
34
Q

How do you treat an uncomplicated neuropathic ulcer?

A
  • Will often heal with topical therapy and non-weight bearing and trial of outpatient therapy is warranted
  • Topical dressings should be aimed at maintaining a moist environment with saline impregnated gauze, topical antibiotic ointments, or other similar agents
  • Ulcer should be protected from excessive pressure by placing an accommodative pad around the lesion
  • heavy callus trimmed away
  • '’Healing sandal’
  • Hyperbaric oxygen oxygen therapy
35
Q

What are the options for treating a minor foot infection

A
  • Broad spectrum antibiotics
  • Open debridement and drainage
  • Partial foot amputation
36
Q

How long should one wait to before revascularization to control active infection

A

A short delay (<5 days) is justified

37
Q

What are limb threatening infections?

A

Abcess
Cellulitis
Osteomyelitis
Gangrene

38
Q

How do you treat limb-threatening infections

A
  • immediate hospitalisation
  • Immobilisation
  • IV antibiotics (triple therapy/ Augmentin / Clindamycin and cipro)
  • Cultures from the depth of the ulcers should be sent
  • patients with abscess formation or necrotizing fasciitis must undergo prompt incision, drainage and debridement
  • Wounds should be packed open with saline moistened gauze, and dressings should be changed 2-3 times a day. Wounds should be checked daily and debridement repeated as needed
  • Adequate dependant drainage is crucial
39
Q

What does underlying osteomyelitis require

A
  • Bony resection
  • Antibiotics
  • Amputation
40
Q

What are the surgical options for a diabetic foot

A
  • open surgical bypass

- endovascular intervention

41
Q

What is the general targets/ advice for a diabetic patient?

A
  • Zero smoking
  • Physical activity: 180 minutes/ week
  • BP: < 140/90
  • Cholesterol: Total (<5); LDL(<2.2); HDL( >1)
  • HBA1C: <6.5 %
  • BMI (<25)
42
Q

What is the management of charcot foot?

A
  • Extended period of non-weight bearing and castor splint immobilisation
  • Accommodative foot wear
  • Stabilizing procedure after disease reached quiescent stage
  • Amputation: severe uncorrectable deformities, chronic ulcers with unsalvagable foot, failed open reconstructions
43
Q

Who are candidates for primary amputation ( inappropriate for traditional vascular procedures)

A
  • Elderly patients with severe dementia who are non-ambulatory or bed-ridden or who have severe flexion contractures of the knee or hip
  • patients with terminal cancer with a very short life expectancy or similar lethal co-morbidities are better served by endovascular intervention or primary amputation
  • Patients with unsalvagable foot due to extensive necrosis from ischemia or infection
44
Q

What are some off-loading strategies

A
  • bed rest
  • crutches
  • wheelchairs
  • casting
  • foams or padding
  • healing shoes
  • Walking boots
45
Q

The do’s of patient foot education

A
  • wash feet daily, dry well, inspect
  • Check hidden areas carefully
  • Anti-fungal powder
  • careful nail hygiene
  • early treatment of wounds
  • wear comfortable, well fitted shoes
  • natural fibre socks are best
46
Q

Donts of patient foot education

A

DON’T:

  • Walk barefoot
  • Wear new shoes without ‘breaking in’
  • Leave wounds untreated
  • burn your feet
  • Cut nails too short
  • Ignore discomfort
47
Q

Acute indications for referral

A
  • Callus formation
  • Ulceration
  • Ischaemic change
  • Acute local sepsis
  • Non-healing trauma
48
Q

Chronic indications for referral

A
  • Recurrent callus/ ulceration
  • Worsening deformity
  • Worsening neuropathy
  • Deteriorating sugar control
  • onset of ischaemic symptoms

Gen Surgery (31 decks)

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