A 6-year-old child is brought to the emergency department with a supracondylar fracture of the humerus. Clinically, the child has a palpable but diminished radial pulse, normal hand colour, and normal capillary refill time. A second child with a similar fracture has an absent radial pulse, pale hand, delayed capillary refill (>3 seconds), and cold fingers. Which finding best distinguishes a fracture with brachial artery *compression* from one with brachial artery *injury*?

Explanation

## Brachial Artery Compression vs. Injury in Supracondylar Fractures ### Pathophysiology **Key Point:** The critical distinction is whether the vascular compromise is due to *mechanical compression* (by the displaced fracture fragment) or *true arterial injury* (intimal tear, thrombosis, or transection). | Feature | Compression | Arterial Injury | |---------|-------------|----------------| | **Mechanism** | Fracture fragment compresses patent artery | Intimal tear, thrombosis, or transection | | **Pulse Status** | Absent or diminished | Absent | | **Hand Perfusion** | May improve with reduction | Remains poor despite reduction | | **Capillary Refill** | May normalize after reduction | Remains delayed >3 sec | | **Colour** | May improve after reduction | Remains pale/cyanotic | | **Angiography Finding** | Compression, patent lumen | Intimal flap, occlusion, or pseudoaneurysm | | **Management** | Gentle closed reduction → restore pulse | Vascular surgery consultation; may need repair | ### Clinical Approach **High-Yield:** **Restoration of pulse and perfusion after gentle closed reduction** is the single best discriminator: - **Compression:** Pulse returns, hand becomes warm and pink, capillary refill normalizes → vascular injury unlikely - **Arterial Injury:** Pulse remains absent or weak, perfusion does not improve → vascular repair may be needed **Clinical Pearl:** A child with an absent radial pulse and a supracondylar fracture should undergo **gentle closed reduction immediately** (in the ED, under anesthesia if available). If the pulse returns and perfusion improves, the artery was compressed; if it does not, vascular imaging (ultrasound Doppler or CT angiography) and vascular surgery consultation are warranted. **Mnemonic:** **COMPRESS vs. INJURE** - **C**losed reduction **Restores** pulse → **Compression** - **I**njury **I**gnores reduction → needs **Intervention** (vascular surgery)