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Orthopaedics
Emergency Medicine

Scaphoid Fracture

High EvidenceUpdated: 2025-12-26

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Red Flags

  • Snuffbox Tenderness -> Treat as Fracture (MRI required)
  • Proximal Pole Fracture -> High AVN Risk (Surgery indicated)
  • Displaced Fracture (>1mm) -> Non-Union Risk
  • Humpback Deformity -> Permanent Flexion Block
Overview

Scaphoid Fracture

1. Clinical Overview

Summary

The scaphoid is the most commonly fractured carpal bone (60-70%). It is unique due to its Retrograde Blood Supply (entering distally and flowing proximally) and its role as the mechanical link between the proximal and distal carpal rows. Fractures of the Waist (most common) and Proximal Pole are at high risk of Avascular Necrosis (AVN) and Non-Union. Diagnosis requires a high index of suspicion; X-rays miss 20% of acute fractures ("Occult Fracture"). MRI is the gold standard for confirmation. Management has shifted following the SWIFFT Trial (2020): Undisplaced waist fractures are treated non-operatively (Cast). Displaced or proximal pole fractures require Herbert Screw fixation. [1,2,3]

Key Facts

  • Mechanism: Fall On Outstretched Hand (FOOSH) with wrist extension >90° and radial deviation.
  • Healing Time: Slow. Distal Pole (4-6 weeks), Waist (8-12 weeks), Proximal Pole (12-24 weeks).
  • Blood Supply: The dorsal carpal branch of the Radial Artery enters the dorsal ridge at the waist and supplies the proximal 80% retrogradely.
  • Occult Fracture: If X-ray is normal but pain persists, immobilize and MRI. Do not wait for 2 weeks (old practice) if MRI is available.

Clinical Pearls

"The Humpback Deformity": An unstable scaphoid fracture collapses into flexion. The distal fragment flexes, the proximal fragment extends (DISI). If this heals in a "humpback" position, wrist extension is permanently blocked.

"Snuffbox is Sensitive, Tubercle is Specific": Tenderness in the Anatomical Snuffbox is highly sensitive but non-specific (Radial nerve, tendonitis). Tenderness on the Scaphoid Tubercle (volar) and pain on Axial Compression (telescoping the thumb) are more specific for fracture.

"SNAC Wrist": Failure to heal leads to Scaphoid Non-Union Advanced Collapse. This is a predictable pattern of arthritis spares the radiolunate joint until the very end.

2. Epidemiology

Demographics

  • Incidence: 29 per 100,000.
  • Age: Young active males (15-30 years). Rare in children (physis fails first) and elderly (radius fails first).
  • Sex: Male > Female.

Risk Factors for Non-Union

  1. Proximal Pole: Watershed vascularity.
  2. Displacement: >1mm step.
  3. Delay in Treatment: Immobilisation >4 weeks post-injury.
  4. Smoking: Vasoconstriction.
  5. Instability: DISI deformity (Lunocapitate angle >15°).
3. Pathophysiology

Anatomy

  • Surface: 80% covered in articular cartilage (limited vascular entry points).
  • Blood Supply:
    • Dorsal Carpal Branch (Radial Artery): Enters vascular foramina on the dorsal ridge. Supplies proximal 80% (Retrograde).
    • Superficial Palmar Branch: Supplies blood to distal tubercle (20%).
  • Implication: A waist fracture severs the dorsal supply to the proximal pole.

Biomechanics

  • The scaphoid flexes during wrist flexion and radial deviation.
  • It extends during wrist extension and ulnar deviation.
  • Fracture disconnects the proximal row (Lunate/Triquetrum) from the distal row (Trapezium/Trapezoid/Capitate).
4. Classification

Mayo Classification (Anatomic)

  1. Tubercle: Benign. Good blood supply.
  2. Distal Pole: Good blood supply.
  3. Waist: Most common (70%). Vulnerable.
  4. Proximal Pole: Poor blood supply. High AVN risk.

Herbert Classification (Stability)

  • Type A (Acute Stable):
    • A1: Tubercle.
    • A2: Incomplete hairline waist.
  • Type B (Acute Unstable):
    • B1: Distal Oblique.
    • B2: Complete Waist (Displaced).
    • B3: Proximal Pole.
    • B4: Trans-scaphoid Perilunate Dislocation.
  • Type C: Delayed Union (>6 weeks).
  • Type D: Non-Union.
5. Clinical Presentation

Symptoms

Signs

  1. Snuffbox Tenderness: Patient extends thumb. Palpate between EPL and EPB/APL.
  2. Scaphoid Tubercle Tenderness: Palpate volarly at the distal wrist crease.
  3. Axial Compression: Compress thumb along its axis towards the radius.
  4. Assessing ROM: Often limited extension.
Pain
Deep, dull ache in radial wrist.
Location
Anatomical Snuffbox.
Aggravation
Push-ups, gripping.
6. Investigations

Imaging Protocol

  1. X-Ray (Scaphoid Series):
    • PA, Lateral, Oblique.
    • Ziter View (PA with Ulnar Deviation): Elongates scaphoid.
    • Sensitivity: 80%.
  2. MRI:
    • Gold Standard for Occult Fracture.
    • Shows oedema (bruising) vs fracture line.
  3. CT Scan:
    • Best for determining displacement and union (bridging trabeculae).
    • Crucial for surgical planning (Humpback deformity).
7. Management Algorithm
                 SCAPHOID FRACTURE
                        ↓
                 IS IT DISPLACED?
          (>1mm step or Proximal Pole?)
           ┌────────────┴─────────────┐
          NO                         YES
    (Stable Waist)               (Unstable)
          ↓                           ↓
   CONSERVATIVE CAST               SURGERY
   (Below Elbow)             (Screw Fixation)
   (8-12 Weeks)                    (ORIF)
          ↓                           ↓
       UNION ON CT?              UNION ON CT?
        ┌─────┴─────┐              ┌────┴────┐
       YES         NO           YES         NO
        ↓           ↓            ↓          ↓
    MOBILISE     SURGERY      MOBILISE    REVISION
                 (Graft)                  (Graft)

Note: The SWIFFT Trial supports casting for undisplaced waist fractures. Proximal pole fractures require surgery.

8. Management: Protocols

1. Conservative (Casting)

  • Device: Below Elbow Cast. (Thumb Spica is unnecessary - studies show no difference).
  • Position: Glass holding position.
  • Duration:
    • Distal: 4-6 weeks.
    • Waist: 8-12 weeks.
  • Monitoring: X-ray at 2 weeks, 6 weeks, 12 weeks. CT at 12 weeks to confirm union.

2. Surgical Fixation

  • Indications:
    • Proximal Pole.
    • Displacement >1mm.
    • Comminution.
    • Perilunate dislocation.
    • High-demand athlete (faster return to sport).
  • Implant: Herbert Screw (Headless Compression Screw). Differential pitch threads compress the fracture.
  • Approaches:
    • Volar: For Waist/Distal. Preserves blood supply.
    • Dorsal: For Proximal Pole. Direct axial alignment.
9. Complications

Scaphoid Non-Union

  • Definition: No healing at 6 months.
  • Rate: 5-10% of waist fractures.
  • Treatment: Screw Fixation + Bone Graft (Matti-Russe or Vascularized).

Avascular Necrosis (AVN)

  • Proximal pole dies and collapses. appears dense (white) on X-ray.
  • Treatment: Vascularized Bone Graft (1,2-ICSRA from Radius) or salvage.

SNAC Wrist (Arthritis)

  • Stage 1: Radial Styloid - Scaphoid.
  • Stage 2: Scaphoid Fossa of Radius.
  • Stage 3: Capitolunate.
  • Sparing: Radiolunate joint is preserved.
  • Salvage: Proximal Row Carpectomy (PRC) or 4-Corner Fusion.
10. Evidence & Guidelines

The SWIFFT Trial (Dias et al. 2020)

  • RCT comparing Surgery vs Cast for Undisplaced Waist Fractures.
  • Result: No difference in patient outcomes (DASH score) at 1 year. Surgery had more complications and cost more.
  • Conclusion: Cast is best for stable waist fractures.

Cast Type (Clay et al. 1991)

  • RCT comparing Colles Cast (wrist only) vs Scaphoid Cast (thumb spica) vs Above Elbow.
  • Result: No difference in union rates.
  • Conclusion: Thumb immobilization is not strictly necessary for waist fractures.
11. Patient Explanation

Why is this fracture tricky?

The scaphoid bone is like an island. It only gets blood from one bridge. If the fracture breaks that bridge, the other side of the island starves and dies (AVN). That's why we take it so seriously.

Why the long cast?

Because the blood flow is slow, it takes 3 months to heal, whereas a normal wrist break takes 6 weeks. You have to be patient. If we take the cast off too early, it will stop healing.

Do I need surgery?

If the bones are lined up perfectly and it's in the middle of the bone, a cast works just as well as surgery (SWIFFT study). Surgery doesn't make it heal significantly faster, but it adds risks of infection and nerve damage. We usually save surgery for the "bad" breaks (displaced or proximal).

What if it doesn't heal?

We call this a Non-Union. It usually doesn't hurt much at first, but over 5-10 years it will cause severe arthritis. We usually recommend fixing a non-union with a bone graft to prevent that arthritis.

12. References
  1. Dias JJ, et al. Surgery versus cast immobilisation for adults with a bicortical fracture of the scaphoid waist (SWIFFT): a pragmatic, randomised, controlled trial. Lancet. 2020.
  2. Herbert TJ, Fisher WE. Management of the fractured scaphoid using a new bone screw. J Bone Joint Surg Br. 1984. (The Herbert Screw).
  3. Gelberman RH, et al. The vascularity of the scaphoid bone. J Hand Surg Am. 1980.
13. Examination Focus (Viva Vault)

Q1: Explain the Retrograde Blood Supply. A: The Dorsal Carpal Branch of the Radial Artery enters the dorsal ridge at the waist of the scaphoid. It supplies the proximal 80% of the bone by flowing backwards (distal to proximal). A waist fracture isolates the proximal pole from this supply.

Q2: What is the management of a symptomatic patient with a normal X-ray? A: Immobilize in a splint/cast and arrange an MRI Scaphoid as soon as possible (or CT if MRI unavailable). Do not discharge.

Q3: Describe the stages of SNAC wrist. A: Stage 1: Styloid-Scaphoid arthritis. Stage 2: Radio-Scaphoid arthritis. Stage 3: Capitolunate arthritis. Stage 4: Pancarpal arthritis. Key Feature: The Radio-Lunate joint is preserved (until stage 4).

(End of Topic)

Last updated: 2025-12-26

At a Glance

EvidenceHigh
Last Updated2025-12-26

Red Flags

  • Snuffbox Tenderness -> Treat as Fracture (MRI required)
  • Proximal Pole Fracture -> High AVN Risk (Surgery indicated)
  • Displaced Fracture (>1mm) -> Non-Union Risk
  • Humpback Deformity -> Permanent Flexion Block

Clinical Pearls

  • **"SNAC Wrist"**: Failure to heal leads to **S**caphoid **N**on-Union **A**dvanced **C**ollapse. This is a predictable pattern of arthritis spares the radiolunate joint until the very end.

Guidelines

  • NICE Guidelines
  • BTS Guidelines
  • RCUK Guidelines