What is the appropriate management for a mildly displaced scaphoid fracture (≤1 mm displacement)?

Management of Mildly Displaced Scaphoid Fractures

For mildly displaced scaphoid fractures (≤1 mm displacement), percutaneous screw fixation is the preferred treatment to minimize complications and expedite return to function, though cast immobilization remains an acceptable alternative for carefully selected patients who can tolerate prolonged immobilization.

Key Decision Point: Fracture Location

The anatomic location of the fracture fundamentally determines management strategy:

• Proximal pole fractures require surgical intervention even when minimally displaced due to the tenuous retrograde blood supply and high risk of avascular necrosis 1
• Waist and distal pole fractures with ≤1 mm displacement can be managed either operatively or non-operatively based on patient factors 2

Operative Management (Preferred for Most Patients)

Percutaneous screw fixation offers superior outcomes for mildly displaced fractures:

• Achieves nearly 100% union rates with minimal complications 2
• Maintains anatomic alignment and prevents progression to greater displacement 3
• Allows earlier mobilization and faster return to work/activities 2
• Can be performed using volar or dorsal approaches with fluoroscopic and arthroscopic guidance 2

Technical Considerations

• Cannulated screws (either Herbert-Whipple or AO/ASIF) effectively maintain fracture alignment and promote healing 3
• Both screw types improve the height-to-length ratio and lateral intrascaphoid angle, which correlate with improved wrist range of motion 3
• Accurate central placement in the proximal pole is achievable with either system 3

Non-Operative Management (Alternative Approach)

Cast immobilization can be considered for select patients, but requires vigilant monitoring:

• Initial thumb spica cast for 6 weeks 4
• CT scan at 6 weeks is critical to objectively measure fracture gap and predict delayed union 4
• If fracture gap >2 mm on CT at 6 weeks, proceed immediately to percutaneous fixation 4
• If gap <2 mm, continue casting for additional 2-4 weeks 4

Critical Pitfalls with Conservative Management

• Displacement >1 mm carries 55% nonunion risk and 50% avascular necrosis risk if treated conservatively 5
• Even fractures that unite with casting alone require prolonged immobilization and have higher rates of painful malunion 5
• Malunion and nonunion predispose to late carpal osteoarthritis 5
• Up to 25% of scaphoid fractures are radiographically occult initially, so clinical examination findings (snuffbox tenderness, scaphoid tubercle tenderness) take precedence over normal radiographs 1

Risk Factors for Delayed Union

When counseling patients, consider these factors that prolong healing time:

• Increasing patient age correlates with longer time to union 3
• Greater initial displacement (even within the "mild" range) extends healing time 3
• Smoking significantly delays union regardless of treatment method 3

Imaging Protocol

• Begin with standard wrist radiographs including dedicated scaphoid views 6
• If clinical suspicion remains high despite negative radiographs, proceed directly to MRI without contrast (sensitivity 94.2%, specificity 97.7%) rather than presumptive casting 6
• CT without contrast is the alternative if MRI is contraindicated or unavailable 6
• For confirmed fractures managed conservatively, CT at 6 weeks is essential to guide continued treatment 4

Treatment Algorithm

1. Confirm diagnosis with appropriate imaging (radiographs ± MRI/CT)
2. Assess fracture location: Proximal pole → surgical fixation mandatory 1
3. For waist/distal fractures with ≤1 mm displacement:
   • Preferred: Percutaneous screw fixation for faster recovery and lower complication rates 2
   • Alternative: Cast immobilization with mandatory CT at 6 weeks 4
4. If conservative management chosen: Convert to surgical fixation if gap >2 mm on 6-week CT 4

Therapies to Avoid

• Do not use low-intensity pulsed ultrasound (LIPUS) for scaphoid fractures, as there is no evidence supporting its benefit 7
• Avoid non-vascularized bone grafts if avascular necrosis develops; use vascularized grafts instead 7