A 35-year-old female office worker presents with a 3-month history of persistent wrist pain and weakness following a FOOSH injury. She was initially treated with a wrist immobilizer for 4 weeks based on clinical suspicion of scaphoid fracture, but imaging at that time was inconclusive. She now complains of pain in the anatomical snuffbox, weakness of grip, and occasional clicking sensation. Examination reveals tenderness over the scaphoid tubercle and a positive scaphoid shift test. Plain radiographs show a lucent line across the scaphoid waist with minimal displacement. What is the most likely complication if this fracture remains untreated?

Explanation

## Scaphoid Fracture Complications **Key Point:** Avascular necrosis (AVN) is the most serious long-term complication of untreated or inadequately treated scaphoid fractures, particularly those involving the proximal pole. The proximal pole has a tenuous blood supply, making it vulnerable to ischemic necrosis. **High-Yield:** Scaphoid fractures at the **waist or proximal pole** carry the highest risk of AVN because the blood supply enters distally and retrograde flow to the proximal pole is compromised when the fracture disrupts vascular continuity. ## Vascular Anatomy & Risk Factors | Fracture Location | Blood Supply Pattern | AVN Risk | Healing Time | |---|---|---|---| | **Distal third** | Excellent (multiple entry points) | <1% | 6–8 weeks | | **Middle/waist** | Moderate (primarily distal entry) | 5–10% | 10–12 weeks | | **Proximal pole** | Poor (retrograde only) | 20–50% | 12–16 weeks | **Clinical Pearl:** The scaphoid is unique among carpal bones in having **retrograde blood supply** — the nutrient vessels enter at the distal pole and travel proximally. A fracture at the waist or proximal pole interrupts this flow, leaving the proximal fragment ischemic. ## Pathophysiology of AVN in Scaphoid Fractures ```mermaid flowchart TD A[Scaphoid waist/proximal fracture]:::outcome --> B[Disruption of retrograde blood supply]:::action B --> C[Proximal pole becomes ischemic]:::urgent C --> D{Fracture immobilized adequately?}:::decision D -->|No| E[Nonunion develops]:::urgent E --> F[Prolonged ischemia of proximal pole]:::urgent F --> G[Avascular necrosis]:::outcome D -->|Yes| H[Union occurs, AVN prevented]:::outcome ``` **Mnemonic:** **SCAPHOID AVN RISK** = **Waist and Proximal pole** fractures with **delayed/inadequate immobilization** and **nonunion**. ## Clinical Presentation of AVN - Persistent pain despite immobilization - Loss of grip strength - Clicking or clunking sensation in the wrist - Radiographic changes (sclerosis, fragmentation) appearing weeks to months after injury - Progressive wrist dysfunction ## Why This Patient Is at High Risk 1. **Fracture location:** Waist fracture — moderate-to-high AVN risk 2. **Delayed diagnosis:** Initial imaging was inconclusive; fracture may have been untreated for weeks 3. **Prolonged symptoms:** 3-month history suggests nonunion or delayed union 4. **Clinical signs:** Persistent snuffbox tenderness and scaphoid shift test positivity indicate ongoing instability ## Prevention & Management - **Early diagnosis and immobilization** are critical to prevent AVN - Thumb spica immobilization for 8–12 weeks (longer for proximal pole fractures) - Repeat imaging at 10–14 days and 6–8 weeks to confirm healing - Surgical fixation (percutaneous screw) for displaced fractures or nonunion - MRI or CT to detect early AVN changes (sclerosis, fragmentation) [cite:Rockwood & Green's Fractures in Adults, Ch 8; Campbell's Operative Orthopaedics, Ch 56]