Leg ulcers

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Contents

Introduction

Epidemiological studies have shown that leg ulcers are present in 3–4% of the population aged more than 65. Management of such ulcers is often not optimal and recurrence is common. Consequently, ulcers result in considerable disability and expense. Improved results will follow a rigorous diagnostic approach, more specialized medical care and critical application of compression to facilitate healing.

Aetiology and pathogenesis

Impaired venous return

Musculo-venous pumps, the most important of which is the calf muscle pump, augment venous return to the heart. The pumps work best when the veins are patent, the valves competent and the pump used by regular exercise.

Venous insufficiency results from failure of the normal mechanisms returning venous blood from the lower limb, particularly incompetence of valves. Incompetence of the deep venous system may follow deep vein thrombosis (DVT) or occur spontaneously. Incompetence of the venous values causes a reduction in the volume of blood expelled by the calf-muscle pump. The calf muscle pump may also be impaired by limited ankle joint mobility caused by arthritis. With increasing obesity and a sedentary lifestyle in an ageing population, the calf-muscle pump may be simply not used.

The common pathway is ambulatory venous hypertension, which leads to soft tissue damage in the leg and eventually ulceration.

Oedema

Raised venous pressure alters the fluxes across the wall of the capillaries so that fluid accumulates in the tissues. Lack of mobility and prolonged standing add a gravitational component so patients often describe the swelling worsening during the day.

Development of collateral pathways

Small venules and veins dilate and attempt to develop alternative connections to the deep venous system. The walls of these veins are fragile and the veins are exposed to high pressure, so they may bleed externally or rupture in the subcutaneous tissue, leading to skin pigmentation.

Impaired nutrition of the skin and subcutaneous tissue

With sustained ambulatory venous hypertension in the lower extremity, there is impaired tissue perfusion. Atrophy and fibrosis results in the thinning of the subcutaneous tissue of the lower one-third of the leg, giving an ‘inverted champagne bottle’ appearance.

Ulcers

Minor injury, which may be unrecognised, can initiate leg ulceration. Healing is poor because of the impaired nutrition of the tissues and tissue breakdown follows. Ulceration can be compounded by infection, particularly streptococcal cellulitis.

Arterial disease

This is the predominant cause of about 20% of leg ulcer cases and a contributing factor, with venous disease, in a further 20%. As arterial insufficiency can often be corrected, it is important that arterial perfusion is checked even if the clinical appearance of an ulcer is typically venous.

Other causes

There is a miscellaneous group that comprises only 10% of patients with ulcers. Ulcers associated with hypertension (Martorell's ulcers) occur predominantly on the anterior and lateral aspects of the calf. The ulcers are distinguished from arterial ulcers by their site. Multiple ulcers may occur and may be painful. Treatment is conservative with healing often delayed.

A common injury is a fall that lifts a distally based skin flap which can leave a post-traumatic ulcer.

Several systemic diseases are associated with leg ulceration including rheumatoid arthritis, inflammatory bowel disease and vasculitis.

Finally, but most important, malignant change (Marjolin's ulcer), usually squamous cell carcinoma, should be suspected in any long-standing ulcer or one with an atypical appearance or that fails to heal despite adequate management. Biopsy of the ulcer edge is then indicated.

Clinical presentation

Chronic venous insufficiency

The patient presents with ulcers, often recurrent, and the history may extend over many years. The ulcers may be painful in the early stages, relieved by elevation of the leg. The most common site is on the medial side of the lower third of the calf. On examination, the ulcer is usually irregular in outline and surrounded by eczematous and/or pigmented skin with a base of granulation tissue. Careful serial measurement of the size of the ulcer will help determine if healing or progressive ulceration is occurring.

Arterial disease

The ulcer may be anywhere on the lower leg, characteristically over bony prominences such as the malleoli. The pain is worse when the leg is elevated and relieved when the leg is hanging down. The ankle pulses are absent.

Investigations

General investigations should include a full blood examination, fasting blood glucose and serum albumin estimation. With atypical ulcers or non-healing ulcers, markers for connective tissue disorders such as rheumatoid serology should be considered and a biopsy is mandatory.

Local investigations

Measurement of ankle blood pressure

Measurement of the ankle/brachial pressure index (ABI) should be performed to check the arterial circulation with a Duplex ultrasound scan if the ABI is abnormal to determine the site and severity of any arterial disease present. Angiography can then be performed on an intention-to-treat basis, aiming to restore arterial perfusion to normality by angioplasty or bypass surgery.

Venous duplex ultrasound

This test has supplanted venography in the assessment of chronic venous insufficiency. The veins are examined to determine the venous anatomy, patency and valvular competence. It is important to determine if there is superficial venous insufficiency present as this can be corrected surgically more easily than deep venous insufficiency.

Venous haemodynamics

Normally venous blood is emptied from the calf with muscular contraction and then slowly refills. Measurement of venous pressure or venous recovery time (the time taken for venous refilling) can quantitate the degree of venous insufficiency present and help differentiate between superficial and deep venous incompetence. These tests are generally performed only in specialised centres and include non-invasive tests such as strain gauge, photo-plethysmography and air plethysmography. The refilling time measured using these methods correlates well with that determined by direct venous pressure measurement. Air plethysmography provides more sophisticated indices of lower extremity venous function. These parameters complement the anatomic information demonstrated with venous ultrasound scanning.

Treatment

The principles of treatment have come to be applied more aggressively in recent years (Management algorithm for leg ulcers). Such treatment should be directed to correct the underlying cause of the ulcer, to optimise healing and to prevent recurrence.

Treatment of the underlying cause

Venous insufficiency

An immediate concern is to control oedema of the subcutaneous tissue and to minimise the sequelae. This is best done by keeping the patient ambulatory by wearing elastic stockings or using compression bandaging although occasionally bedrest with elevation of the leg is required. Neglected or inadequate lower extremity compression is the commonest reason for failed healing or early ulcer recurrence. Elderly patients need considerable physical and emotional support to help them persevere with stockings, particularly for those with arthritis or limited mobility.

Surgery has a limited place in relieving venous obstruction, restoring valvular competence or dealing with superficial venous insufficiency or perforating veins. Superficial varicose veins should be treated, unless they are forming important collateral around obstructed deep veins. Patients with only superficial incompetence and normal deep veins are an important group to identify as they can be cured of the tendency to ulceration. Incompetent calf perforating veins, communicating between the deep and superficial venous systems, can be treated by sclerotherapy or by endoscopic surgery.

Attempts have been made to relieve venous obstruction or restore valve function by surgical means. The most successful procedure has been femoro-femoral vein bypass to relieve unilateral iliac venous obstruction. Procedures to restore valve function by applying cuffs to restore valvular competence or autotransplantion of vein segments containing competent valves into an incompetent deep vein have met with limited success. These measures are applicable to only about 1–2% of patients with venous ulceration.

Skin grafting can hasten healing, but in almost all patients it is unnecessary. Performance of a skin graft does not remove the need for the other measures described; in particular, the need to wear supporting stockings remains an essential component of the post-operative care.

The most important therapeutic measure to heal venous ulcers, supported by Level 1 evidence, is external compression preferably by stockings or alternatively, well applied elastic bandaging. The choice of dressing is far less important, other than to cover the ulcer and protect the skin. A variety of elastic stockings are now available with application devices to make it easier for patients to put them on. These stocking are designed to provide graduated compression, greatest around the ankle, less proximally. Graduated compression should be applied with a 40 mm Hg pressure gradient at the ankle level, tapering to 20 mm Hg at the knee. The ankle arterial pressure should be measured before compression bandaging is applied to ensure that there will be no compromise of arterial inflow. In most cases a below-knee stocking provides adequate support.

Provide conditions to allow healing

Careful attention should be given to nutrition as elderly, immobile patients with painful ulcers may neglect themselves.

Treat infection

In addition to these general measures, local skin care and antibiotic therapy for any associated cellulitis will help control infection and provide optimal local conditions for healing. It is important to distinguish between invasive infection and contamination of the wound. Prolonged courses of antibiotics should not be given because this will usually result in colonisation of the wound by strains of bacteria resistant to the antibiotics.

Provide and maintain optimum conditions for healing

The two major elements of this are to remove dead tissue and to apply appropriate dressings. Dead tissue can be removed enzymatically or surgically. Although correct application of external compression is the most important therapeutic measure, dressings are important as wounds heal best in warm, moist conditions. There are now a large number of products available to provide and maintain optimum conditions for healing. The choice of dressing will depend on the depth of the wound and the amount of exudate.

Prevention of recurrence

Treatment that results in healing of an ulcer is not sufficient. The next objective is to prevent recurrence, by general measures such as life-style change encouraging greater mobility and weight loss and local measures, the most important of which is perseverance with surgical stocking support.
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