Leg Ulcer Assessment OSCE — Venous, Arterial, and Neuropathic Differentials

Why This Station Is Tested

Leg ulcer assessment is a core clinical skill tested in both surgical and medicine OSCE circuits. Correctly identifying venous, arterial, or neuropathic aetiology directs radically different management — compression bandaging (venous) is contraindicated in arterial disease and can cause limb-threatening ischaemia. Examiners test whether you can distinguish these systematically and safely.

Before You Begin

Introduce yourself, confirm patient identity, obtain consent, and expose both legs fully from the groin. Ask about pain before touching — arterial ulcers are typically very painful; neuropathic ulcers are painless. Have gloves on for wound assessment.

Systematic Inspection

Site and Distribution

Ulcer Characteristics

Surrounding Skin Signs

Note haemosiderin deposition (brown staining from extravasated RBCs — venous), lipodermatosclerosis (woody induration of lower leg — chronic venous), atrophie blanche (white areas of avascular skin — venous/mixed), varicose veins, and any evidence of cellulitis.

Vascular Examination

Peripheral Pulses

Palpate femoral, popliteal (patient's knee flexed 20–30°), posterior tibial (behind medial malleolus), and dorsalis pedis (lateral to EHL tendon on dorsum of foot). Absent or diminished foot pulses suggest arterial disease. Record each pulse as present/absent/weak.

Buerger's Test

Elevate both legs to 45° for 2 minutes — arterial insufficiency causes pallor (Buerger's angle: angle at which pallor develops; <20° = severe ischaemia). Then sit patient up and hang legs over the edge of the bed — reactive hyperaemia (dusky/brick-red colour) in arterial disease = positive Buerger's test. Normal limbs remain pink throughout.

Capillary Refill Time

Press on the nail bed for 5 seconds, release, and count until colour returns — normal <2 seconds. Delayed CRT suggests arterial insufficiency.

ABPI — Ankle-Brachial Pressure Index

ABPI = Ankle systolic BP / Brachial systolic BP (highest of both arms)

Neurological Assessment

Assess for peripheral neuropathy (common in diabetic neuropathic ulcers): 10g monofilament test (at metatarsal heads and great toe), vibration sense (128Hz tuning fork at great toe), pinprick, and proprioception. Absent protective sensation confirms neuropathic component.

Completing the Examination

Offer to examine: full peripheral vascular system, neurological examination of lower limbs, and assess for venous incompetence (Trendelenburg test, hand-held Doppler). Offer to perform wound swab if signs of infection. State you would review current dressings and measure wound dimensions.

Management Principles

Venous ulcers: four-layer compression bandaging (if ABPI >0.8), leg elevation, wound debridement, treatment of underlying varicose veins (EVLA or foam sclerotherapy if appropriate). Arterial ulcers: vascular surgical referral, angioplasty or bypass if indicated, risk factor modification (antiplatelet, statin, smoking cessation), avoid compression. Neuropathic ulcers: offloading (total contact casting or orthotic footwear), wound debridement, infection treatment, optimise glycaemic control.

Frequently Asked Questions

"How do I distinguish a venous from an arterial ulcer in the OSCE without any investigations?"

The clinical distinction relies on site, ulcer characteristics, surrounding skin, pain, and vascular examination findings. Venous ulcers are typically over the medial gaiter area, have irregular sloping edges, a moist granulating or sloughy base, surrounding haemosiderin staining and lipodermatosclerosis, are associated with varicose veins, produce moderate aching pain relieved by elevation, and have normal peripheral pulses with warm feet. Arterial ulcers occur at pressure areas (toes, heel, lateral malleolus), have punched-out edges with a pale necrotic base, surrounding skin is pale, cold, hairless and atrophic, the pain is severe (often worse at night — rest pain — and relieved by hanging the leg down), and peripheral pulses are absent or diminished. In mixed disease (which is common — up to 20% of ulcers), features of both are present, and ABPI is the key investigation to quantify the arterial component.

"What is ABPI and how do you calculate it at the bedside?"

ABPI stands for Ankle Brachial Pressure Index and is the ratio of the highest ankle systolic blood pressure to the highest brachial systolic blood pressure. At the bedside, you use a hand-held Doppler probe and a sphygmomanometer: measure systolic BP in both arms (use the higher reading), then measure systolic BP at both posterior tibial and dorsalis pedis arteries in each ankle (use the higher ankle reading for each side). Divide ankle systolic by brachial systolic for each leg. A normal ABPI is 0.9–1.2. Values below 0.8 indicate significant arterial disease and are a contraindication to full compression bandaging. Values above 1.3 are falsely elevated due to medial arterial calcification (common in diabetes and renal failure) and Duplex ultrasound or toe-brachial pressure index should be used instead. In the OSCE, even if you cannot perform the Doppler, explaining the calculation and its clinical significance scores well.

"What is Buerger's test and how do you perform it correctly?"

Buerger's test assesses the severity of arterial insufficiency in the lower limbs. It has two components: first, elevate both legs to 45° and hold for 1–2 minutes — in arterial disease the foot becomes pale or white (due to inadequate arterial pressure to overcome gravity), and the angle at which pallor first appears is Buerger's angle (normal >90°; <20° indicates critical ischaemia). Second, ask the patient to sit up and hang their legs dependently — in arterial disease, reactive hyperaemia produces a dusky brick-red or cyanotic colour as blood rushes into the dilated, poorly perfused capillaries. This is a positive Buerger's test. Normal limbs remain pink throughout both positions. When performing this in the OSCE, narrate what you are doing and why: "I am going to elevate both legs to 45° and watch for colour changes — this is Buerger's test to assess the severity of any arterial insufficiency."

"What are the causes of leg ulceration and how do you structure a differential in the OSCE?"

The most useful framework is to categorise by aetiology: vascular (venous insufficiency — 70–80% of all leg ulcers; arterial insufficiency — 10–15%; mixed venous/arterial — up to 20%), neuropathic (diabetic peripheral neuropathy, leprosy, B12 deficiency), traumatic (especially in elderly patients on anticoagulants), infective (tropical ulcers — Buruli ulcer, leishmaniasis; ecthyma), malignant (Marjolin's ulcer — squamous cell carcinoma arising in chronic venous ulcer; melanoma; Kaposi's sarcoma), haematological (sickle cell disease — medial malleolar; vasculitis — rheumatoid, SLE, polyarteritis nodosa), and pressure ulcers. In the OSCE, after describing the ulcer, say: "The most likely diagnosis given these features is a venous ulcer, but I would like to exclude an arterial component by measuring ABPI and assessing peripheral pulses."

"What is lipodermatosclerosis and what does it indicate?"

Lipodermatosclerosis is a specific finding in chronic venous insufficiency characterised by woody, indurated, tender thickening of the skin and subcutaneous tissue of the lower leg, typically in the gaiter distribution (lower third of leg, around the malleoli). It is caused by chronic venous hypertension leading to fibrin deposition, inflammation, and fibrosis. In the acute phase it can look like cellulitis (erythema and tenderness) but does not respond to antibiotics — it is sometimes called "acute lipodermatosclerosis" and can be confused with DVT or cellulitis. In chronic form, the leg has an inverted champagne bottle or bowling pin appearance — the ankle is narrowed and indurated while the calf is swollen. Haemosiderin deposition (brown discolouration from haemoglobin breakdown) typically accompanies lipodermatosclerosis. Seeing this sign in the OSCE is a strong pointer to venous ulceration.

"What would your management plan be for a newly diagnosed venous leg ulcer?"

Management of venous leg ulcers follows a structured approach. First, confirm the diagnosis and exclude significant arterial disease with ABPI measurement — compression is only safe if ABPI is ≥0.8. Second, wound assessment: dimensions, depth, tissue type (necrotic, sloughy, granulating, epithelialising), signs of infection (surrounding erythema, warmth, purulent exudate, increased pain, systemic features) — wound swab if infected, and appropriate systemic antibiotics (flucloxacillin first-line for cellulitis). Third, initiate four-layer compression bandaging (the gold standard for venous ulcers) — aim for 40 mmHg at the ankle, reduced up the leg. Fourth, leg elevation when resting — above the level of the heart. Fifth, refer to a tissue viability nurse and vascular surgery if the ulcer is not healing at 12 weeks or if arterial disease is identified. Surgical treatment of underlying varicose veins (endovenous laser ablation or foam sclerotherapy) reduces recurrence. Recurrence prevention with compression hosiery after healing is essential.

Related guides: Peripheral Vascular Examination OSCE · Diabetic Foot Examination OSCE · Ankle Examination OSCE · Wound Care and Suturing OSCE · Deep Vein Thrombosis OSCE