A 32-year-old man presents to the emergency department following a fracture of the mid-shaft of the humerus sustained during a motor vehicle accident. On examination, he has wrist drop and inability to extend the thumb at the interphalangeal joint. Sensation is intact over the dorsal first web space. Plain radiographs confirm a displaced mid-shaft humeral fracture. What is the most appropriate next step in management?

Explanation

## Management of Radial Nerve Palsy with Mid-Shaft Humeral Fracture ### Clinical Context Mid-shaft humeral fractures are associated with radial nerve injury in approximately 10–18% of cases. The radial nerve runs in the spiral groove of the humerus and is vulnerable to traction or compression at this level. The vast majority of these injuries are **neurapraxia** (Sunderland Grade I) — a conduction block without axonal disruption — and recover spontaneously. ### Key Point: **In a closed mid-shaft humeral fracture with radial nerve palsy, the standard of care is conservative (non-operative) management with immobilization and watchful waiting, NOT immediate ORIF or nerve exploration.** ### Why Immobilization + Follow-Up is the Correct Answer 1. **Closed fractures with radial nerve palsy** are overwhelmingly managed non-operatively. The nerve injury is almost always neurapraxia from traction/compression, not transection. 2. **Intact sensation over the dorsal first web space** (superficial radial nerve territory) strongly suggests nerve continuity — the nerve is not transected. 3. **Spontaneous recovery** occurs in >90% of cases within 3–6 months with conservative fracture management (coaptation splint, functional brace, or sling). 4. **ORIF is NOT routinely indicated** for radial nerve palsy alone in a closed humeral fracture. ORIF indications include: open fractures, vascular injury, bilateral fractures, floating elbow, or failure of closed reduction — not simply the presence of radial nerve palsy. 5. **Immediate EMG/NCS** (Option A) is not useful acutely — Wallerian degeneration takes 2–3 weeks to manifest on NCS, so early studies cannot distinguish neurapraxia from axonotmesis. 6. **Urgent surgical nerve repair** (Option B) is reserved for open fractures with visible nerve damage or failure of recovery after 3–6 months of observation. ### High-Yield: **The Holstein-Lewis fracture** (distal-third spiral humeral fracture) has a higher risk of radial nerve entrapment and may warrant earlier exploration, but standard mid-shaft fractures do not. ### Clinical Pearl: **Wrist drop + loss of thumb IP extension = classic posterior interosseous / radial nerve motor deficit.** Intact sensation in the first web space (superficial radial nerve) indicates the nerve is in continuity, making neurapraxia the most likely diagnosis and conservative management the appropriate first step. ### When to Consider Nerve Exploration / ORIF - Open fractures with visible nerve damage - Vascular injury requiring surgical repair - No recovery of nerve function after 3–6 months (then EMG/NCS to guide decision) - Intraoperative findings of complete transection during fracture fixation done for other indications [cite: Rockwood & Green's Fractures in Adults, 8th ed., Ch. 11; Campbell's Operative Orthopaedics, 13th ed.]