Classification And Staging

After completing this basic assessment, it will now be possible to classify the diabetic foot. For practical purposes, the diabetic foot can be divided into two distinct entities:

the neuropathic foot and the neuroischaemic foot. Neuropathy is nearly always found in association with ischaemia, so the ischaemic foot is best called the neuroischaemic foot. In rare cases the foot may clinically be ischaemic without signs of neuropathy, but in practice, the diabetic ischaemic foot is treated in the same way as the neuroischaemic foot, and thus, we have continued with the two main divisions.

It is essential to classify the diabetic foot by differentiating between the neuropathic and the neuroischaemic foot as their management will differ in many respects. Usually there will be no doubt as to which category the foot should be placed in. However, if the examiner has any doubt as to the correct classification, then the foot should be regarded as neuroischaemic, because if a neuroischaemic foot is wrongly classified as neuropathic, with resulting failure to do further tests to confirm ischaemia and adapt the care plan accordingly, this may lead to preventable catastrophe and loss of the foot.

Neuropathic foot

• The neuropathic foot is a warm, well-perfused foot with bounding pulses and distended dorsal veins due to arteriovenous shunting

• Sweating is diminished so skin and any callus tend to be hard and dry and prone to Assuring

• Toes are flexed and the arch of the foot may be raised

• Ulceration commonly develops on the sole of the foot, associated with neglected callus and high plantar pressures

• Despite the good circulation, necrosis can develop secondary to severe infection

• The neuropathic foot is also prone to bone and joint problems which we refer to as Charcot's osteoarthropathy.

Neuroischaemic foot

• The neuroischaemic foot is a cool, pulseless foot with poor perfusion and almost invariably also has neuropathy

• The colour of the severely ischaemic foot can be a deceptively healthy pink or red caused by dilatation of capillaries in an attempt to improve perfusion

• The neuroischaemic foot may be complicated by swelling, often secondary to cardiac failure or renal impairment

• Ischaemic ulcers are commonly seen around the edges of the foot, including the apices of the toes and the back of the heel, and are associated with trauma or wearing unsuitable shoes (Fig. 1.15)

Neuroischemic Ulcer
Fig. 1.15 Neuroischaemic foot with ulceration on the margins..

• The neuroischaemic foot develops necrosis in the presence of infection or if tissue perfusion is critically diminished

• Even if neuropathy is present and plantar pressures are high, plantar ulceration is rare. This is probably because the foot does not develop heavy callus, which requires good blood flow.

After classification of the diabetic foot, it is necessary to make the appropriate staging in its natural history.

The natural history of the diabetic foot can be divided into six stages as shown:

• Stage 3: Ulcerated foot

• Stage 6: Unsalvageable foot.

The simple staging system covers the entire spectrum of diabetic foot disease but it emphasizes the development of the foot ulcer in stage 3 as a pivotal event demanding urgent and aggressive management. However, each stage demands specific treatment.

Other classifications of the diabetic foot such as the Wagner system, the University of Texas system and the Nottingham S(AD)SAD system are essentially classifications of ulcers and do not cover the whole natural history of the diabetic foot.

The simple staging system used in this book has been created to allow all practitioners, whether experienced in diabetic foot care or not, to make an initial assessment of the diabetic foot at whatever stage in the natural history it might be. The stage sets the place in the natural history and also determines treatment. The aim is to keep all diabetic feet at as low a stage as possible.

Stage 1

At this stage, the patient does not have the risk factors of neuropathy, ischaemia, deformity, callus and swelling rendering him vulnerable to foot ulcers. The normal foot is characterized by no symptoms, including no pain, and examination is normal.

Stage 2

The patient has developed one or more of the risk factors for foot ulceration including neuropathy, ischaemia, deformity, callus and swelling. These risk factors need addressing to reduce susceptibility to ulceration.

Patients without active foot ulceration but a history of ulceration should be regarded as very high risk.

Within stage 2 there are specific conditions which are non-ulcerative but require treatment. These include:

• Severe chronic ischaemia

• Acute ischaemia.

There are also specific complications of neuropathy:

• Neuropathic fractures

• Charcot's osteoarthropathy

• Painful neuropathy.

Stage 3

The foot has a skin breakdown. Although this is usually an ulcer, it is important not to underestimate some apparently minor injuries such as blisters, skin fissures or grazes, all of which have a propensity to become ulcers if they are not treated correctly and fail to heal quickly. Ulceration is usually on the plantar surface in the neuropathic foot (Fig. 1.16) and on the margin in the neuroischaemic foot (Fig. 1.17).

Stage 4

The foot has developed infection with the presence of purulent discharge or cellulitis which can complicate both the neuropathic foot (Fig. 1.18) and the neuroischaemic foot (Fig. 1.19).

Stage 5

Necrosis has supervened. In the neuropathic foot, infection is usually the cause. In the neuroischaemic foot, infection is still the most common reason for tissue destruction although ischaemia contributes (Fig. 1.20). In some cases ischaemia alone can lead to necrosis of a previously intact foot, with slow onset of dry necrosis and necrotic toes which appear shrivelled (Fig. 1.21).

Stage 6

The foot cannot be saved and will need a major amputation.

Reasons for major amputation:

Foot Classification

Fig. 1.16 Neuropathic ulcer on the plantar surface.

Worms The Feet

Fig. 1.19 Cellulitis in a neuroischaemic foot with ulcer that is a portal of entry for infection.

Fig. 1.16 Neuropathic ulcer on the plantar surface.

Fig. 1.17 Ischaemic ulcer on the medial border of the first metatarsophalangeal joint.

Fig. 1.18 Severe sepsis in a neuropathic foot with oedema, cellulitis, lymphangitis and a bluish tinge to the 3rd toe. Without urgent treatment, necrosis will supervene.

• Extensive necrosis which has destroyed the foot

• Severe infection which puts the life at risk

• Agonizing ischaemic pain which cannot be relieved.

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