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LOWER LIMB ULCERATION

There are a number of causes which lead to ulcers on the lower limb, especially on the foot.

Venous ulcers are the commonest type of leg ulcer in the western world accounting for 80-

85% of all lower limb ulcers. Apart from venous ulcers, other causes of lower limb ulcers

include arterial disease leading to arterial ulcers, diabetes and peripheral neuropathy leading

to neuropathic ulcers, ulcers due to vasculitic conditions such as systemic lupus

erythematosus and rheumatoid arthritis, ulcers due to haematological causes such as

polycythaemia and sickle cell anaemia, and ulcers due to trauma, neoplasia, sarcoidosis and

pyoderma gangrenosum. In this section we will look at the pathogenesis,clinical

features,investigation and management of venous, arterial and neuropathic ulcers, the three

most common types of ulcer encountered in the western world.

Pathogenesis

* Venous ulcers (Fig 10) *

These occur due to sustained venous hypertension or chronic venous insufficiency

secondary to venous disease (such as varicose veins or venous valve malfunction due to

previous DVT), impaired function of the calf muscle pump (due to immobility, arthritis,

paralysis or severe obesity limiting mobility) or congestive cardiac failure. This leads to

repetitive ischaemic reperfusion injury which in turn results in the formation of ulcers.

* Arterial ulcers (Fig 11) *

These are the result of artherosclerosis within the large and medium sized arteries of the

lower limb. The significant ischaemia results in the formation of ulcers.

* Neuropathic ulcers (Fig 12) *

These occur in diabetic patients who have peripheral neuropathy. Peripheral neuropathy

encompasses sensory, motor and autonomic nerve malfunction. Sensory neuropathy leads

to neglect of minor injuries or infections which may progress to ulcers and eventually limb-

threatening injuries. Motor neuropathy leads to a gradual denervation of the intrinsic musclesof the foot which in turn lead to loss of the transverse and longitudinal arches of the foot and

the foot adopting a characteristic claw-like shape. Autonomic neuropathy results in opening

of arterio-venous shunts allowing blood to bypass the skin capillary bed and resulting in an

increased flow of blood through bone, which promotes osteoclastic activity. This in turn

increases the susceptibility of the foot to fracture with minor trauma and Charcot foot

collapse. There are several theories regarding the pathological mechanisms leading to nerve

malfunction in peripheral nueropathy, this is however beyond the scope of this article.

Fig 10. A venous ulcer in the gaiter area of the lower limb, [13].

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Fig 11. An arterial ulcer on the dorsal aspect of the foot.

These ulcers are extremely painful and usually give out a pungent odour, [15].

Fig 12. A neuropathic ulcer at a pressure point on the foot.

The lateral edge of the foot has inward pressure exerted on it by footwear such as shoes

which may contribute to the ulceration, [14].

Clinical features

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* Venous Ulcers *

These are usually located in the gaiter area just proximal to the medial or lateral malleous

within an area of lipodermatosclerosis or haemosiderosis. They are usually painless and it

maybe possible to notice varicose veins proximal to the area of ulceration.

* Arterial ulcers *

These are usually located distally over and between the toes or in pressure points such as

the heels or malleoli. They are usually very painful and have a pungent smell. The limb

maybe appear pale. Palpation of pulses will usually reveal a diminished pulse and the

capillary refill maybe prolonged >2 seconds.

* Neuropathic ulcers *

These are characteristically associated with a warm foot with palpable pulses. Ulcers maybe

located at points of repetitive trauma. Looking at how ones shoe fits onto the foot and the

contact points between the foot and footwear may reveal the mechanism of injury. In certain

situations there maybe concomitant arterial insufficiency leading to absent/reduced pulses.

Examination & Investigations

Management

* Venous ulcers *

Pure superficial venous incompetence based ulcers maybe treated with varicose vein

stripping. These ulcers respond well to surgery and may heal within 4 weeks of the

operation. On the other hand patients who are unfit for surgery or who have deep venous

incompetence are best treated conservatively with occlusive dressings covered by

compression bandages worn from the foot to the knee. These patients require weekly

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dressing change and sometimes ulcer debridement. Topical applications such as antibiotic

and antiseptic creams have not shown to reduce ulcer healing time. Treated in this way 80-

90% of ulcers heal by 1 year. It is recommended that patients wear compression stockings

for life to prevent recurrence.

* Arterial ulcers *

As these ulcers are usually very painful they require analgesia. They need to be dressed, but

compression should be avoided as this may worsen tissue ischaemia. In diabetic patients,

good glycaemic control should be advocated. Smokers should be advised to stop smoking.

The ulcers should be debrided of necrotic tissue. If there is significant arterial disease

revascularization should be considered.

* Nueropathic ulcers *

X-rays to assess the bones of the foot and to rule out foreign bodies, osteomyelitis,

fractures, gas or bone collapse. The patient should be adivsed to regularly visit the

chiropodist to aid early recognition of problems with regular debridement of ulcers if already

present. Ulcers in pressure areas that are not infected may be treated with pressure relieving

footwear such as a total-contact cast which distributes pressure on ambulation over the

entire surface area of the foot. The cast needs to be changed every 48 hours to ensure a

snug fit, and then weekly for 8-10 weeks until the ulcer is healed. Any infected or

gangrenous ulcers should be treated promptly with surgical debridement if necessary and

broadspectrum IV antibiotic therapy. If an ischaemic component is suspected,

revascularization should be considered as the ulcers are unlikely to heal in this

circumstance.