In supracondylar fracture of the humerus, which nerve is most commonly injured?

Explanation

## Nerve Injury in Supracondylar Fracture **Key Point:** The median nerve is the most frequently injured nerve in supracondylar fractures of the humerus, occurring in 10–20% of cases. ### Mechanism of Injury The median nerve is vulnerable due to its anatomical course across the anterior aspect of the distal humerus. In supracondylar fractures, particularly extension-type fractures (which account for 95% of cases), the proximal fragment displaces posteriorly and the distal fragment angulates anteriorly, stretching the median nerve across the fracture site. ### Nerve Injury Pattern in Supracondylar Fractures | Nerve | Incidence | Type of Injury | Clinical Finding | |-------|-----------|----------------|------------------| | Median nerve | 10–20% | Stretch, compression | Loss of thumb opposition (AIN), weakness of pronation | | Anterior interosseous nerve (AIN) | 5–10% | Stretch, compression | Loss of thumb IP flexion, index finger DIP flexion | | Radial nerve | 2–5% | Stretch, traction | Wrist drop (rare in pure supracondylar) | | Ulnar nerve | 1–2% | Stretch, compression | Claw hand (uncommon) | **High-Yield:** Anterior interosseous nerve (AIN) injury is the second most common and is a branch of the median nerve, so combined median + AIN injury is not uncommon. ### Clinical Pearl Nerve injuries in supracondylar fractures are often **neurapraxia** (stretch injury) and recover spontaneously in 80–90% of cases within 3–6 months. Persistent neurological deficit after 3 months warrants exploration. **Mnemonic:** **MARS** — Median, AIN, Radial, (rarely) Supratrochlear — in order of frequency of nerve injury in supracondylar fractures.