Scaphoid Fracture
Pain in the anatomic snuff box indicates a scaphoid fracture until proven otherwise. 1, 2, 3
Clinical Significance
The scaphoid is the most commonly fractured carpal bone, typically occurring after a fall on an outstretched hand (FOOSH) that causes acute dorsal flexion of the wrist. 4, 5 This injury pattern shows a bimodal distribution, with higher rates in younger patients (<18 years) during sports activities and older patients (>65 years) from ground-level falls. 2
Key Clinical Findings
Anatomic snuff box tenderness is the hallmark clinical sign, though it has limited specificity when used alone. 6, 7 The following examination findings should be assessed:
- Tenderness in the anatomic snuff box - 100% sensitive but only 9% specific when used alone 7
- Scaphoid tubercle tenderness - 100% sensitive with 30% specificity 7
- Pain with longitudinal compression of the thumb - 100% sensitive with 48% specificity 7
- Pain with ulnar deviation - important predictor in clinical decision rules 6
- Swelling of the anatomic snuff box - significant predictor of fracture 6
When these clinical signs are combined, sensitivity remains 100% while specificity improves dramatically to 74%, making the clinical diagnosis far more accurate. 7
Diagnostic Approach
Initial Imaging
Begin with standard 3-view wrist radiographs including posteroanterior, lateral, and 45° semipronated oblique "scaphoid view." 1, 3 This dedicated scaphoid view may reveal otherwise occult fractures. 1
Advanced Imaging for Occult Fractures
If initial radiographs are negative but clinical suspicion remains high (positive snuff box tenderness), proceed directly to MRI without IV contrast rather than empiric casting and repeat radiographs. 1, 2, 3 This represents a paradigm shift from older practice patterns.
MRI without IV contrast is the preferred advanced imaging modality with the highest sensitivity (94.2%) and specificity (97.7%) for diagnosing scaphoid fractures. 1, 2, 3 MRI has the added advantage of detecting concomitant ligament injuries (particularly scapholunate ligament tears) that may affect treatment decisions. 3
CT without IV contrast is an acceptable alternative if MRI is contraindicated or unavailable, offering superior visualization of bone cortex and trabeculae with shorter acquisition times. 1, 3 CT is particularly useful for specific fractures like the hook of hamate. 8, 1
Bone scintigraphy can reliably exclude occult scaphoid fractures with high sensitivity but has lower specificity due to uptake from bone contusions and osteoarthritis. 8, 1, 3 This may be reasonable for claustrophobic patients who cannot tolerate MRI. 8, 1
Critical Pitfalls to Avoid
Never rely on anatomic snuff box tenderness alone - it has extremely poor specificity (9%) and will lead to massive overtreatment. 7 Combine multiple clinical signs to achieve 74% specificity while maintaining 100% sensitivity. 7
Do not perform empiric casting with delayed repeat radiographs when initial films are negative - this outdated approach delays definitive diagnosis. 1, 3 Proceed directly to MRI or CT instead. 1, 3
Ensure adequate radiographic views are obtained initially - a minimum of 3 views including the dedicated scaphoid view is required to avoid missed diagnoses. 3
Special Considerations
In children under age 9, scaphoid fractures are extremely rare, and pain in the anatomic snuff box is a particularly poor indicator of bone injury in this population. 9 The actual bone pathology in pediatric patients with snuff box tenderness may not be a true scaphoid fracture. 9
Stress fractures of the scaphoid, though rare, must be considered in athletes (particularly tennis players) with chronic wrist pain and snuff box tenderness, even without acute trauma. 4