What radiographic views are suggested for evaluating a thumb fracture?

Radiographic Views for Thumb Fracture

For suspected thumb fractures, obtain a minimum 3-view radiographic series consisting of anteroposterior (AP), lateral, and oblique views of the thumb. 1, 2

Standard Imaging Protocol

Initial Radiographic Views

• Three views are mandatory for adequate evaluation of thumb fractures, as relying on only 2 views is inadequate for detecting fractures in the extremities 1, 3
• The standard series should include:
  • Posteroanterior (PA) or anteroposterior (AP) view 1
  • True lateral view 1, 3
  • Oblique view (both internal and external rotation if possible) 1, 2

Why Three Views Matter

• The oblique view uniquely reveals abnormalities in 4.8% of distal extremity trauma cases and increases diagnostic confidence significantly 2
• Addition of the oblique view changed interpretation in 70 of 1461 examinations, converting equivocal findings to definitive diagnoses in many cases 2
• Lack of a true lateral or true AP view is the most frequent reason for diagnostic errors (71% of missed or misdiagnosed finger/thumb fractures) 3

Special Considerations for Thumb Injuries

Sesamoid Fractures

• Oblique views are often necessary to document sesamoid bone fractures at the thumb metacarpophalangeal (MCP) joint, as these fractures may be completely invisible on standard AP views 4
• All sesamoid fractures in one study were visible only on oblique projections 4

Ulnar Collateral Ligament Injuries ("Skier's Thumb")

• Stress testing is mandatory even when bony avulsion fracture appears minimal on radiographs, as bony fragments may represent fragmentation rather than true ligamentous avulsion 5
• Standard radiographs cannot differentiate between true avulsion fractures (ligament attached to fragment) and isolated bone fragments with complete ligament disruption 5

Common Pitfalls to Avoid

• Never accept poor quality radiographs or inadequate views as a basis for treatment 3
• Do not allow finger superimposition on lateral views, which can lead to misjudgment of displaced fractures 3
• An oblique view complements but cannot replace a true lateral view 3
• If initial 3-view radiographs are negative but clinical suspicion remains high (persistent pain, swelling, tenderness), consider MRI without IV contrast or repeat radiographs in 10-14 days after immobilization 1

Advanced Imaging

• CT is usually not indicated during acute thumb injury evaluation 1
• MRI without IV contrast may be appropriate if initial radiographs are negative but clinical suspicion persists 1