Arterial ulcers

Overview

•Arterial ulcers = severe end of PAD spectrum (critical limb ischaemia); account for ~10-20% of lower limb ulcers

•Underlying mechanism: atherosclerosis → luminal narrowing → distal tissue hypoxia → ulceration

•Represent Fontaine stage III (rest pain) or IV (tissue loss/ulceration)

Presentation

•Location - toes, toe tips, heel, dorsum of foot, pressure points, between digits

•Morphology - small, deep, 'punched-out', well-defined borders; pale/grey/necrotic base; minimal bleeding

•Pain - severe; worse at night and on elevation; relieved by dependency (hanging leg down)

•Surrounding skin - hairless, pale/dusky, cool; nail dystrophy; muscle wasting

•Pulses - weak or absent (dorsalis pedis, posterior tibial)

•Buerger's angle - <20 degrees; foot blanches on elevation, dusky red on dependency

🎯
Arterial ulcer pain is worse on elevation and relieved by dependency - the exact opposite of venous ulcers (which are relieved by elevation). A key differentiator.

Investigations

🥇 First-line

•ABPI (ankle-brachial pressure index) using hand-held Doppler - cornerstone investigation for all lower limb ulcers

•Bloods: FBC, CRP, HbA1c, U&E, albumin - infection, diabetes, anaemia, nutritional status

•Wound swab - only if clinical signs of infection present

🏆 Gold standard

•CT angiography or MR angiography - defines arterial stenosis/occlusion before revascularisation

🥈 Second-line

•Duplex ultrasound - non-invasive arterial imaging

ABPI value
Interpretation
>0.9
Normal
0.7-0.9
Mild PAD (claudication range)
0.5-0.7
Moderate PAD
<0.5
Severe PAD - arterial ulcers common
<0.3
Critical ischaemia - urgent vascular referral
>1.2-1.3
Falsely elevated - calcified vessels (diabetes); use toe-brachial index

⚠️
ABPI must be measured BEFORE applying any compression bandaging, even in presumed venous ulcers.

Management

•Definitive treatment = revascularisation (ulcer will not heal without restored perfusion) - urgent vascular surgery referral

•Compression bandaging - absolutely contraindicated; risks precipitating gangrene in critically ischaemic limb

•Infection present: flucloxacillin - first-choice oral antibiotic

•Penicillin allergy alternatives: doxycycline, clarithromycin, or erythromycin (in pregnancy)

•Second-choice (if first-line fails, guided by microbiology): co-amoxiclav or co-trimoxazole

Complications

•Gangrene - dry (ischaemia) or wet (+ infection); urgent vascular input required

•Osteomyelitis - suspect if ulcer probes to bone ('probe to bone' test positive)

•Amputation - required for non-salvageable limbs

•Cardiovascular events - very high MI and stroke risk from systemic atherosclerosis; 5-year mortality in critical limb ischaemia ~20-25%

Arterial vs venous ulcers

Arterial vs venous ulcer comparison
FeatureArterialVenous
LocationToes, heel, dorsum of footGaiter area (medial malleolus)
MorphologyPunched-out, deep, pale/necrotic baseShallow, irregular, sloughy base
PainSevere; worse on elevation, relieved by dependencyMild-moderate; relieved by elevation
BleedingMinimalBleeds freely
SkinHairless, cool, pale/duskyHaemosiderin staining, lipodermatosclerosis
PulsesAbsent/weakNormal
ABPI<0.5 (often)0.9-1.2
CompressionCONTRAINDICATEDFirst-line treatment

ABPI value	Interpretation
>0.9	Normal
0.7-0.9	Mild PAD (claudication range)
0.5-0.7	Moderate PAD
<0.5	Severe PAD - arterial ulcers common
<0.3	Critical ischaemia - urgent vascular referral
>1.2-1.3	Falsely elevated - calcified vessels (diabetes); use toe-brachial index

Feature	Arterial	Venous
Location	Toes, heel, dorsum of foot	Gaiter area (medial malleolus)
Morphology	Punched-out, deep, pale/necrotic base	Shallow, irregular, sloughy base
Pain	Severe; worse on elevation, relieved by dependency	Mild-moderate; relieved by elevation
Bleeding	Minimal	Bleeds freely
Skin	Hairless, cool, pale/dusky	Haemosiderin staining, lipodermatosclerosis
Pulses	Absent/weak	Normal
ABPI	<0.5 (often)	0.9-1.2
Compression	CONTRAINDICATED	First-line treatment