For a deep tissue injury to the heel, do I need an arterial or venous ultrasound evaluation?

Deep Tissue Injury to the Heel: Arterial Ultrasound Evaluation is Indicated

For a deep tissue injury (DTI) to the heel, you should obtain arterial ultrasound evaluation (ankle-brachial index and/or duplex ultrasound) to assess perfusion, as adequate blood flow is critical for healing and the heel is predominantly supplied by the posterior tibial artery. Venous ultrasound is not routinely indicated unless there are specific signs of venous thrombosis.

Why Arterial Assessment is Essential

The Heel's Vascular Supply and Healing Requirements

• The heel receives the majority of its blood supply from the posterior tibial artery, with only minimal contribution from the posterior branch of the peroneal artery, making arterial perfusion assessment critical for healing 1
• Deep tissue injuries begin in muscle closest to bone and can rapidly deteriorate despite appropriate interventions, making early identification of vascular compromise essential 2
• The heel is the anatomical location with the highest prevalence of deep tissue injury, and most commonly appears over the coccyx, sacrum, buttocks, and heels 2, 3

Clinical Evidence for Arterial Assessment

• In patients with heel ulcers, transcutaneous oximetry (TcPO2) can reveal critical ischemia in the perilesional area even when pedal pulses are palpable, demonstrating that clinical examination alone is insufficient 1
• The angiosome concept is clinically useful in heel ulcer treatment—if decreased blood flow to the heel region is not detected and direct flow is not restored, healing may be delayed or impaired 1

Recommended Arterial Evaluation Approach

Initial Screening with Ankle-Brachial Index (ABI)

• Perform ABI measurement with the cuff applied just above the malleolus, measuring at both the pedalar artery and posterior tibial artery, keeping the lowest value for calculation 4
• An ABI <0.9 has 87% sensitivity and 97% specificity for diagnosing vascular injury and warrants further imaging 4
• An ABI >1.40 suggests arterial calcification and requires alternative testing such as toe-brachial index or duplex ultrasound 4

When to Proceed to Advanced Arterial Imaging

• If ABI is abnormal (<0.9 or >1.40), proceed to duplex ultrasound as the first-line imaging method to assess anatomy and hemodynamic status of lower extremity arteries 4
• Consider CT angiography or magnetic resonance angiography when revascularization is being considered 4
• Duplex ultrasound should specifically evaluate the posterior tibial artery given its critical role in heel perfusion 1

Venous Ultrasound: Only When Clinically Indicated

When Venous Assessment is NOT Routinely Needed

• Venous ultrasound is not part of standard evaluation for deep tissue injury unless there are specific clinical signs suggesting deep venous thrombosis 4
• The primary concern with DTI is tissue perfusion and healing, not venous drainage 2

When to Consider Venous Ultrasound

• Perform focused compression ultrasound at the common femoral and popliteal veins if there is unilateral leg swelling, warmth, or other signs suggesting DVT 4, 5
• If symptoms persist or worsen despite initial negative ultrasound, repeat imaging within 5-7 days or sooner if clinical concern is high 5, 6
• Consider venous imaging if there are risk factors unique to DTI patients that overlap with DVT risk, including vasopressor use, haemodialysis, or prolonged immobility 7

Critical Clinical Pitfalls to Avoid

• Do not assume adequate perfusion based on palpable pedal pulses alone—transcutaneous oximetry or duplex ultrasound may reveal regional ischemia even with palpable pulses 1
• Do not delay arterial assessment—DTI can rapidly deteriorate, and between 9.3% and 27% progress to full-thickness tissue loss 7
• Do not miss factors associated with deterioration—cooler skin on infrared thermography and negative capillary refill are associated with worse outcomes, while positive capillary refill may indicate better prognosis 7
• Do not order venous ultrasound reflexively—focus on arterial perfusion unless specific venous pathology is suspected 4

Additional Risk Factors to Address

• Patients who develop DTI are typically older with lower body mass index than those with other pressure injuries 2
• Unique risk factors for DTI include anemia, vasopressor use, haemodialysis, and nicotine use, all of which may compound vascular insufficiency 7
• Stiffer mattresses result in higher contact pressures and internal maximum shear strains at the heel, and friction coefficients below 0.4 may reduce internal shear strains 3