What is the initial assessment and management of acute scaphoid wrist fracture?

Initial Assessment of Acute Scaphoid Wrist Fracture

Begin with standard 3-view wrist radiographs (posteroanterior, lateral, and 45° semipronated oblique "scaphoid view"), and if negative but clinical suspicion remains high, proceed directly to MRI or CT without contrast rather than empiric casting. 1, 2

Clinical Assessment

Key Physical Examination Findings

• Anatomical snuffbox tenderness - though this alone is insufficient for diagnosis, as 80% of patients with isolated snuffbox tenderness have no fracture 3
• Scaphoid tubercle tenderness on palpation 4
• Pain with axial compression of the thumb 4
• Assess for other wrist injuries - 13% of patients with suspected scaphoid injury have other wrist pathology unrelated to the scaphoid 3

Mechanism of Injury

• Typically results from forceful wrist extension during a fall on an outstretched hand 5

Radiographic Evaluation

Initial Imaging

• Standard 3-view radiographic series is mandatory as the first-line examination 1, 2
• Look specifically for:
  • Scapholunate diastasis >4 mm suggesting dorsal intercalated segmental instability 1
  • Dorsal tilt of lunate >10° indicating carpal instability 1
  • Intra-articular extension into the radiocarpal joint 1, 2

When Initial Radiographs Are Negative

If clinical suspicion remains high despite negative radiographs, do NOT routinely immobilize and wait 2 weeks for repeat films. 3, 4

Advanced Imaging Options (in order of preference):

MRI without IV contrast is the preferred next study:

• Highly sensitive for occult fractures through detection of bone marrow edema 1
• Detects concomitant soft tissue injuries including scapholunate ligament tears that may affect treatment 1
• Can be used as an alternative to presumptive casting and repeat radiographs 1
• IV contrast adds no value in acute fracture assessment 1

CT without IV contrast is an acceptable alternative:

• Superior for visualizing bone cortex and trabeculae 1
• Shorter acquisition times than MRI and easier to perform in casted patients 1
• Preferred for specific fractures like hook of hamate 1
• Less sensitive than MRI for bone bruises and soft-tissue injuries 1

Bone scintigraphy (if MRI/CT unavailable):

• High sensitivity - normal bone scan reliably excludes occult scaphoid fracture 1
• Lower specificity than CT/MRI due to uptake from bone contusions, osteoarthritis 1
• Reasonable alternative in claustrophobic patients 1
• Cost-effective when performed early rather than after weeks of immobilization 3

Fracture Classification

Assess Stability

Classify as either stable/undisplaced or unstable/displaced 5:

Unstable/Displaced fractures have:

• >1-2 mm displacement 5
• Scapholunate angle abnormalities 1
• Associated carpal malalignment 1

Stable/Undisplaced fractures (B1 or B2 patterns):

• Minimal to no displacement 6
• No carpal instability 1

Assessment for Complications

Evaluate for Associated Injuries

• Ligamentous injuries - particularly scapholunate and lunotriquetral ligaments 1
• Distal radius fractures - look for intra-articular extension and "longhorn sign" 2
• Other carpal bone injuries 3

Risk Factors for Non-Union

• Proximal pole fractures - assess blood supply concerns 1
• Displaced fractures - higher risk of avascular necrosis 1
• Delayed diagnosis - contributes to non-union risk 3

Common Pitfalls to Avoid

• Do not rely solely on snuffbox tenderness - this has poor specificity and leads to unnecessary immobilization in 80% of cases 3
• Do not routinely immobilize all suspected fractures for 2 weeks without advanced imaging - this results in needless treatment and healthcare costs 3
• Do not obtain inadequate radiographic views - minimum 3 views required to avoid missed diagnosis 2
• Do not assume radiographs are sufficient - 2-5% of scaphoid fractures are missed on initial presentation 3
• Do not forget to assess for carpal instability on initial radiographs, as this changes management from stable to unstable classification 1