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Leg ulcers

What are they?

An ulcer is defined as a discontinuity of the skin exhibiting complete loss of the epidermis and often parts of the dermis and even subcutaneous fat.

Rocky:: Leg ulcers, it follows, must represent this discontinuity occurring on the leg?


Clubber Lang: My prediction? PAIN.

Leg ulcers may be acute or chronic. Acute ulcers are those that follow normal phases of healing; they show signs of healing within 4 weeks. In contrast, chronic ulcers persist for longer than 4 weeks and are of poorly understood origin. 

What causes them?

Leg ulcers are broadly categorised into three groups: Arterial, venous and diabetic.

Arterial insufficiency - Poor circulation of lower leg and foot, and is usually attributable to atherosclerosis. Thor arteries fail to deliver oxygen and nutrients to the leg and foot, culminating in tissue breakdown.

Venous insufficiency - Due to improper functioning of one-way valves in veins. 

Veins drain blood from the foot and lower legs, against gravity, towards the heart. Two mechanisms assist this movement:  

  • Calf muscle pump - pushes blood towards the heart during exercise
  • One-way valves - prevent blood flowing with gravity

Impaired functioning of these mechanisms as occurs in reflux through the valves, obstruction of the veins and impaired calf pumping result in pooling of blood in the lower leg, just below the ankle.

The increased venous pressure causes fibrin deposits around the capillaries, which then impede the flow of oxygen and nutrients to the muscle and skin tissue. Just like in arterial insufficiency, the death of tissue cells leads to ulceration.

Diabetic ulcers - caused by a combination of arterial blockage and nerve damage. Although diabetic ulcers can occur elsewhere, they are most common on the foot.

Nerve damage reduces the sensitivity to temperature and pressure, rendering patients more prone to injury and subsequent 'neuropathic' ulceration.

What are the risk factors?

Arterial

  • Diabetes
  • Smoking
  • Hypercholesterolaemia
  • Hypertension
  • Renal failure
  • Obesity
  • Rheumatoid arthritis

Venous

  • Varicose veins
  • History of leg swelling
  • History of blood clots in deep veins
  • Sitting or standing for long periods
  • Hypertension
  • Multiple pregnancy
  • Increasing age and immobility

Features

Arterial

  • Usually found on feet, heels or toes.
  • Frequently painful, particularly at night or when legs are at rest or elevated. The pain is relieves when the legs are lowered since this causes greater blood flow to the legs.
  • Ulcer base contains greyish, unhealthy-looking granulation tissue.
  • Border of ulcers appear as if they are 'punched out.'
  • Associated with cold white or bluish, shiny feet.
  • There may be cramp-like pains when walking which are relieved by rest.
  • Can be assessed by Arterial Brachial Pressure Index (ABPI). Normal values fall between 0.92 - 1.3. ABPI below 0.9 is suggestive of arterial disease.

Venous

  • Located below the knee, most often on the inter part of the ankles.
  • Relatively painless, unless infected.
  • Associated with swollen, aching lower legs that are more comfortable when elevated.
  • May be associated with varicose veins due to incompetence of the lower superficial venous system (50%).
  • May be associated with lipodermatosclerosis.
  • Surrounded by mottled brown or black and/or dry, itchy and reddened skin (venous eczema).

Diabetic

  • Similar characteristics to arterial ulcers but are characteristically seen over pressure points - heels, tips of toes, between toes
  • In response to pressure, the skin increases in thickness but a minor injury breaks this down resulting in ulceration.

Treatment

Venous leg ulcers should be treated with exercise, elevation at rest and compression. However, compression should not be used if there is significant existing arterial disease as this will aggravate an inadequate blood supply.

Arterial leg ulcers should be referred to a vascular surgeon since surgery may be required to relieve narrowing of the arteries. Urgent referral s needed if ABPI is below 0.5.

Regardless of the cause of the ulcer, meticulous skin care and cleansing of the wound are essential.

Antibiotics are not indicated unless there is tissue infection. This is likely if the ulcer becomes more painful or the surrounding skin becomes red, hot or swollen (cellulitis). 

 


Arterial ulcer


Venous ulcer

His ulcer was misdiagnosed.