Compression is the treatment that heals venous leg ulcers; everything else is supportive. But the same compression applied to a limb with arterial insufficiency can cause necrosis and, in the worst case, amputation. The decisive step is therefore not the choice of dressing but the ankle-brachial index before the first bandage is applied.

Indications

Venous leg ulcer — about 70% of all leg ulcers.
Chronic venous oedema, lipodermatosclerosis, stasis dermatitis.
Prevention of recurrence after a healed venous ulcer.
After deep vein thrombosis with post-thrombotic syndrome.

Differential diagnosis

Feature	Venous ulcer	Arterial ulcer	Diabetic foot ulcer
Site	Gaiter area, above the medial malleolus	Toes, heel, lateral malleolus, pressure points	Beneath the metatarsal heads, toes, heel
Edge	Irregular, shallow	Sharp, punched-out	Surrounded by callus
Wound bed	Fibrin-covered, granulating, copious exudate	Dry, necrotic, pale	Variable, often deep
Pain	Moderate, relieved by elevation	Severe, worse on elevation, better when dependent	Often painless (neuropathy)
Surrounding skin	Hyperpigmentation, oedema, lipodermatosclerosis, eczema	Pale, hairless, atrophic, cold	Dry, hyperkeratotic
Pulses	Palpable	Weak or absent	May be palpable despite ischaemia
ABI	> 0.9	< 0.9	Often falsely high

Three lower legs side by side showing a venous ulcer above the medial malleolus, an arterial ulcer over the lateral malleolus and on a toe, and a callus-rimmed ulcer on the sole of the foot — Figure 1. The three most common leg ulcers differ above all in their location. On the left, a venous ulcer in the gaiter area above the medial malleolus: superficial, with an irregular shallow edge, a moist granulating bed with fibrin, and surrounding brown hyperpigmentation, oedema and eczema. In the middle, arterial ulcers over the lateral malleolus and on the toe tips: small, deep, with a sharp punched-out edge and a dry necrotic base, in pale, hairless and atrophic skin on a thin leg without oedema. On the right, a diabetic foot ulcer at the pressure point beneath the first metatarsal head, round and deep with a thick rim of callus around the edge, in dry cracked skin. Mixed ulcers occur and may look venous while arising on a limb with arterial insufficiency — which is why the ankle-brachial index, not the appearance, determines whether compression may be applied.

Contraindications to compression

The ankle-brachial index measured with Doppler determines whether compression may be applied at all, and if so at what pressure. Palpable foot pulses are not an acceptable substitute, and in patients with diabetes or renal failure the index may be falsely normal because of medial sclerosis — in that case add toe pressure measurement.

flowchart TD
  A[Leg ulcer] --> B[Measure the ankle-brachial index with Doppler before the first bandage]
  B --> C{Index}
  C -- At least 0.80 --> D[Full compression, 40 mmHg at the ankle]
  C -- 0.50 to 0.79 --> E[Reduced compression, 20 to 30 mmHg]
  E --> F[Vascular surgical assessment in parallel]
  C -- Below 0.50 --> G[Compression contraindicated]
  G --> H[Urgent vascular surgical assessment]
  C -- Above 1.40 or diabetes with suspected medial sclerosis --> I[The index cannot be interpreted: measure toe pressure]
  I --> J{Toe pressure}
  J -- Below 30 mmHg --> G
  J -- At least 30 mmHg --> E
  D --> K[Reassess the index every three to six months and on any new pain]
  E --> K

Absolute:

ABI < 0.5 or toe pressure < 30 mmHg.
Decompensated heart failure — compression of both legs acutely increases preload.
Untreated deep vein thrombosis in the acute phase.
Septic phlebitis, ongoing soft tissue infection with systemic involvement.

Relative:

Condition	Adaptation
ABI 0.5–0.79	Reduced compression (20–30 mmHg) under vascular surgical supervision
Diabetes with neuropathy	Reduced compression, closer monitoring — the patient cannot feel pressure injury
Peripheral neuropathy of other cause	As above
Severe pain	Titrate the pressure up gradually
Rheumatoid arthritis with vasculitis	Individual assessment

Repeat the ABI every three to six months during ongoing compression therapy, and always in the event of new or increasing pain.

Preparation and equipment

Doppler for the ankle-brachial index, blood pressure cuff.
Lukewarm tap water or saline for cleansing, swabs.
Sharp spoon (curette), ring curette, toothed forceps, scissors, no. 15 scalpel.
Topical anaesthetic cream (lidocaine–prilocaine) or infiltration anaesthesia for painful debridement.
Wound bed dressing chosen by exudate volume, edge protection (zinc paste, barrier film).
Compression materials: two-layer system, four-layer system, short-stretch bandage, zinc paste bandage (Unna boot), or a class 2–3 compression stocking.
Tape measure for ankle circumference — this governs the choice of material and bandaging technique.

Procedure

Assessment

History: duration, previous ulcers, DVT, varicose veins, claudication, diabetes, smoking, character of the pain.
Measure and trace the ulcer; photograph it with a ruler in the image. A reduction in size of 40% within four weeks predicts healing — failure to shrink should prompt reconsideration of the diagnosis.
Palpate the pulses and measure the ankle-brachial index with Doppler.
Culture only in the presence of clinical signs of infection — all chronic wounds are colonised, and a culture taken without clinical suspicion leads only to unnecessary antibiotics.
Biopsy any ulcer that has not healed within three months despite adequate treatment — malignancy (Marjolin's ulcer, basal cell carcinoma) and vasculitis do occur.

Wound debridement

Cleanse with lukewarm tap water or saline; showering the leg is a good option.
Apply topical anaesthetic cream under occlusion for 30–45 minutes before painful debridement.
Remove fibrin, necrosis and callus from the edges with a curette or sharp spoon, using even tangential strokes until granulation tissue or pinpoint bleeding appears.
Avoid damaging granulation tissue. Stop in the event of heavy bleeding or unacceptable pain — debridement can be divided over several visits.
Alternatives in the presence of pain or suspected ischaemia: autolytic debridement with hydrogel, enzymatic debridement, or larval therapy.
Do not debride dry, stable necrosis on an ischaemic limb — it acts as a biological barrier until the circulation has been addressed.

Choice of wound dressing

Wound bed	Dressing
Copious exudate	Foam, alginate, hydrofibre
Moderate exudate	Foam
Dry wound bed	Hydrogel, hydrocolloid
Fibrin-covered	Hydrogel or hydrofibre under compression
Clinically infected	Silver- or iodine-containing dressing, short term; systemic antibiotics for cellulitis
Granulating	Non-adherent, change infrequently

The choice of dressing affects healing time only marginally compared with compression. Choose according to exudate volume and change interval, not by product name. Protect the wound edges from maceration with zinc paste or a barrier film.

Compression bandaging

The target is 40 mmHg at the ankle for a venous ulcer, with pressure decreasing gradually proximally. The bandage is applied in the morning, before the leg has swollen.

The foot is held in 90° dorsiflexion throughout bandaging.
Pad behind the malleoli, over the tendon and along the tibial crest — this is where pressure injuries arise.
Start at the base of the toes, include the heel, and bandage upwards to just below the popliteal fossa.
Use 50% overlap and even tension according to the manufacturer's markings.
If the ankle circumference is below 18 cm, additional padding is required to achieve the correct pressure without pressure necrosis.
Check the toes: colour, temperature and capillary refill immediately after bandaging.

Four steps of compression bandaging on the same lower leg: padding, starting over the ball of the foot, a figure-of-eight around the heel, and the finished bandage up to the knee — Figure 2. Bandaging in four steps, with the foot in 90° dorsiflexion throughout. First padding as an even sleeve with extra wadding behind the malleoli, over the Achilles tendon and along the tibial crest — this is where pressure injuries arise. The bandage starts with two turns around the foot just behind the base of the toes, then passes in a figure-of-eight around the heel so that the hollow of the heel is completely covered, and is then wound upwards to just below the popliteal fossa with 50% overlap between turns. The pressure is highest at the ankle and decreases gradually proximally; a leg bandaged more tightly above than below congests rather than decongests. The toes are left free so that colour, temperature and capillary refill can be assessed immediately after bandaging.

System	Change interval	Comment
Four-layer system	Once weekly	High, sustained pressure; requires trained staff
Two-layer system	Once weekly	Thinner, fits inside ordinary shoes
Short-stretch bandage	Daily or every other day	High working pressure, low resting pressure — useful when the circulation is impaired
Zinc paste bandage (Unna boot)	Once weekly	Also treats stasis dermatitis
Class 2–3 compression stocking	Daily	Prevention of recurrence after healing; requires that the patient can put it on

Levels of compression. The class denotes the pressure at the ankle, and the pressure must always decrease proximally. The prescription should state both the level and the ankle-brachial index on which it rests.

Class	Pressure at the ankle	Use
Class 1	18–21 mmHg	Mild oedema, superficial varicose veins; may be used at ABI 0.50–0.79 when higher pressure is not tolerated
Class 2	23–32 mmHg	Venous insufficiency, after a healed venous ulcer, after DVT; corresponds to reduced compression
Class 3	34–46 mmHg	Marked oedema and active venous ulcer — the level corresponding to the 40 mmHg target
Class 4	> 49 mmHg	Lymphoedema; not relevant for leg ulcers in primary care

Compression is contraindicated at an ABI < 0.50 or a toe pressure < 30 mmHg, and at an ABI of 0.50–0.79 the pressure is limited to 20–30 mmHg alongside vascular surgical assessment. Full compression, 40 mmHg at the ankle, requires an ABI ≥ 0.80.

Complications

Pressure ulcers over the malleoli, the tibial crest and the Achilles tendon from incorrect bandaging.
Ischaemic injury and necrosis from compression applied despite arterial insufficiency.
Contact allergy to dressing materials, lanolin or topical antibiotics — suspect this in new-onset eczema around the ulcer.
Compression-induced peroneal nerve palsy from excessive pressure at the fibular head.
Cellulitis, erysipelas and (rarely) osteomyelitis.
Maceration of the wound edges.
Pain and poor adherence, the most common reason for failure to heal.

Aftercare and follow-up

Lifelong compression after a healed venous ulcer. Without a stocking about two-thirds recur within five years; with a stocking about one-third.
Elevation above heart level for 30 minutes, 3–4 times daily.
The calf muscle pump is part of the treatment — daily walking and ankle mobility exercises.
Skin care with emollients; treat stasis dermatitis with a group II–III topical steroid beneath the compression.
Address the underlying venous insufficiency: refer for duplex ultrasound and consideration of endovenous ablation or sclerotherapy — the procedure appreciably reduces the risk of recurrence.
Nutritional assessment; protein, iron, zinc and albumin all affect healing.
Reassess after four weeks. Reconsider the diagnosis if the ulcer has not shrunk by 40%.

Common pitfalls

Compression without an ABI. The single most dangerous shortcut in Swedish wound care.
Diagnosing a "venous ulcer" without excluding an arterial component — mixed ulcers are common in older patients.
Routine culture of chronic wounds, leading to antibiotics for colonisation.
Ulcers that are never biopsied. A leg ulcer that has not healed within three months should be assessed histologically.
Compression that is too light because the patient found it uncomfortable — this gives no healing and all of the inconvenience.
Inadequate padding behind the malleoli and over the tibial crest.
Stopping compression once the ulcer has healed. Recurrence is then only a matter of time.
Topical antibiotics on chronic wounds — they drive resistance and are a common cause of contact allergy.

Leg ulcers — wound debridement and compression therapy