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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Most commonly fractured carpal bone — young adults, FOOSH mechanism
- Anatomical snuffbox tenderness + scaphoid tubercle tenderness + pain on longitudinal compression of thumb
- Initial X-ray may be NORMAL in up to 20% — if clinically suspected, treat as fracture and reassess
- Retrograde blood supply: proximal pole at HIGH RISK of avascular necrosis (AVN)
- If X-ray negative but clinically suspected: MRI at 2 weeks (gold standard for occult fracture) or treat empirically in thumb spica
Overview
The scaphoid is the most commonly fractured carpal bone, accounting for 60–70% of all carpal fractures. It is vulnerable because it bridges the proximal and distal carpal rows. The critical clinical concern is its retrograde blood supply — the blood supply enters distally and runs proximally, meaning proximal pole fractures are at high risk of avascular necrosis (AVN, ~30–40%) and non-union. Scaphoid fractures are frequently missed on initial X-ray (up to 20% are occult) — a high index of clinical suspicion is essential.
Epidemiology
Scaphoid fractures are most common in young adults (15–30 years), particularly males. The mechanism is a fall on an outstretched hand with wrist dorsiflexion. Fractures are classified by location: waist (~70%, most common), proximal pole (~20%, highest AVN risk), and distal pole (~10%, lowest AVN risk, best prognosis).
Clinical Features
Symptoms
Wrist pain after a fall on outstretched hand — may be dismissed as a "sprain"
Pain on gripping, reduced grip strength
Swelling may be minimal
Signs
Anatomical snuffbox tenderness (between EPL and EPB/APL tendons — radial side of wrist)
Scaphoid tubercle tenderness (volar, at base of thenar eminence)
Pain on longitudinal compression of thumb (telescoping test)
Pain on ulnar deviation of wrist
Investigations
First-line
Scaphoid X-ray seriesAP, lateral, and scaphoid views (PA with ulnar deviation + oblique). Initial X-ray misses ~20% of scaphoid fractures
Second-line
MRI wristGold standard for occult scaphoid fracture — if initial X-ray negative but clinical suspicion high. Sensitivity ~100%. Perform at 2 weeks if empirically immobilised
CT wristAlternative if MRI unavailable — good for fracture displacement and surgical planning
Specialist
Repeat X-ray at 10–14 daysIf MRI unavailable — fracture line becomes visible as bone resorption occurs. Less sensitive than MRI
1
Confirmed fracture — undisplaced
- Below-elbow thumb spica cast (including thumb to IP joint, wrist in neutral) for 6–8 weeks (waist fracture) or 8–12 weeks (proximal pole)
- Fracture clinic review at 2 weeks with repeat X-ray
- CT or MRI at 6 weeks to confirm union before removing cast
2
Confirmed fracture — displaced or proximal pole
- Surgical fixation: open reduction and internal fixation (ORIF) with Herbert screw
- Displaced fractures (>1 mm step or >15° angulation), proximal pole fractures, and those with associated ligament injury
3
Clinical suspicion but X-ray normal
- Treat as a scaphoid fracture: apply thumb spica and arrange MRI or repeat X-ray at 10–14 days
- Do NOT dismiss as a "wrist sprain" — missed scaphoid fractures have serious consequences (AVN, non-union)
Complications
- Avascular necrosis (AVN): Proximal pole: ~30–40% risk. Waist: ~10–20%. Due to retrograde blood supply — proximal fragment loses blood supply
- Non-union: Untreated or late-diagnosed fractures — may require bone graft and fixation
- Osteoarthritis: Long-term consequence of malunion or AVN — scaphoid non-union advanced collapse (SNAC wrist)
- Scapholunate dissociation: Associated ligament injury
UKMLA Exam Tips
- 1Anatomical snuffbox tenderness after FOOSH = scaphoid fracture until proven otherwise
- 2Initial X-ray normal in up to 20% — do NOT reassure patient and discharge. Treat as fracture (thumb spica) and arrange MRI or repeat imaging
- 3Proximal pole fracture has the highest AVN risk (~30–40%) due to retrograde blood supply
- 4The blood supply enters DISTALLY — so the PROXIMAL pole is most at risk of AVN (key anatomy point)
- 5Herbert screw fixation for displaced fractures or proximal pole fractures
- 6Young man with FOOSH + snuffbox tenderness = scaphoid fracture. Elderly woman with FOOSH = think Colles fracture
practicetest your knowledge on scaphoid fractureApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — musculoskeletal and beyond.
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