Scaphoid Fracture
The scaphoid is the most commonly fractured carpal bone, typically occurring after a fall on an outstretched hand (FOOSH). Its retrograde blood supply makes it prone to avascular necrosis and nonunion, requiring high clinical suspicion even when initial X-rays are negative.
Anatomical Basis
The scaphoid spans the proximal and distal carpal rows, acting as a key stabilizer of the wrist. Its blood supply is retrograde (distal to proximal), entering primarily through the dorsal ridge. Fractures, especially at the waist, can disrupt blood flow to the proximal pole, causing avascular necrosis.
Relevant Structures
Mechanism
Fall on outstretched hand (FOOSH) with wrist hyperextension and radial deviation. The scaphoid impacts against the radius. Common in young adults during sports or accidents. The waist (middle third) is the most common fracture site (70%).
Clinical Presentation
- âĒWrist pain after fall, especially with radial-sided tenderness
- âĒSwelling over the radial wrist
- âĒDecreased grip strength
- âĒPain with wrist motion, especially extension
- âĒMay have minimal initial symptoms ("sprained wrist")
Physical Examination
- âAnatomical snuffbox tenderness: High sensitivity for scaphoid injury
- âScaphoid tubercle tenderness: Palpate on volar wrist at base of thenar eminence
- âPain with axial compression of the thumb
- âPain with wrist motion, particularly radial deviation
- âDecreased range of motion
Treatment
- âNon-displaced stable fractures: Thumb spica cast for 8-12 weeks
- âDisplaced fractures (>1mm): Surgical fixation with headless compression screw
- âProximal pole fractures: Often require surgery due to poor blood supply
- âNonunion: Bone grafting with or without vascularized graft
- âIf clinical suspicion with negative X-ray: Immobilize and reimage, or get MRI
Prognosis
Distal third fractures: Excellent healing (nearly 100%). Waist fractures: Good (>90% union with proper treatment). Proximal pole: Fair (higher nonunion and AVN risk). Delayed diagnosis significantly worsens prognosis.
Study Tips
- ðĄBlood supply: Dorsal carpal branch of radial artery enters distally, flows proximally (retrograde)
- ðĄSnuffbox tenderness has high sensitivity but low specificity - must immobilize if suspicious
- ðĄIf X-ray negative but clinically suspicious: treat as fracture, reimage in 2 weeks or get MRI
- ðĄNonunion risk increases with delayed diagnosis, proximal fracture, and displacement
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Common questions about this condition
The scaphoid has a retrograde blood supply - blood enters distally and flows proximally. Fractures through the waist can interrupt blood flow to the proximal pole, which has no alternative supply, leading to bone death (avascular necrosis).
Fresh fractures may not show on X-ray because there's no bone resorption at the fracture site yet. After 10-14 days, osteoclastic activity creates a visible fracture line. MRI can detect fractures immediately by showing bone marrow edema.