Scaphoid Fracture (Adult)

1. Clinical Overview

The scaphoid is the most frequently fractured carpal bone, accounting for 60-70% of all carpal fractures and representing approximately 2-7% of all fractures presenting to emergency departments. [1,2] Predominantly affecting young, active males following falls onto an outstretched hand (FOOSH), scaphoid fractures present unique diagnostic and therapeutic challenges due to the bone's precarious blood supply and critical biomechanical role in wrist function.

The scaphoid occupies a unique anatomical position, bridging the proximal and distal carpal rows and functioning as the mechanical link that translates forces across the wrist. This anatomical arrangement, combined with retrograde blood supply that enters distally and flows proximally, places the scaphoid at particular risk for devastating complications including avascular necrosis (AVN) and non-union. [3,4] Fractures of the waist (70% of cases) and particularly the proximal pole carry the highest risk of these complications.

A critical challenge in scaphoid fracture management is the occult fracture—radiographically invisible in 15-25% of acute presentations despite being genuinely fractured. [5,6] This has led to the clinical maxim: "Tenderness in the anatomical snuffbox should be treated as a fracture until proven otherwise." The advent of early MRI has revolutionized diagnosis, allowing definitive confirmation or exclusion within 24-48 hours and avoiding unnecessary immobilization in the majority of cases. [7,8]

The landmark SWIFFT trial (Surgery versus Cast Immobilisation for Fracture of the Scaphoid waist in Adults), published in The Lancet in 2020, fundamentally changed practice by demonstrating that undisplaced scaphoid waist fractures have equivalent 12-month outcomes whether treated with immediate surgical fixation or below-elbow cast immobilization followed by early fixation of any non-unions. [9] This high-quality randomized controlled trial (n=439) showed no significant difference in patient-rated wrist evaluation (PRWE) scores but identified higher complication rates in the surgical group, supporting initial conservative management for stable fractures.

Key Epidemiological Facts

• Incidence: 29-43 per 100,000 population per year [1,10]
• Age: Peak incidence 20-30 years; rare in children (less than 5 years due to cartilaginous scaphoid) and elderly (> 60 years—Colles fracture occurs instead) [1,2]
• Sex ratio: Male:Female = 4-5:1 [10]
• Mechanism: Fall on outstretched hand with wrist hyperextension (> 90°) plus radial deviation [11]
• Location: Waist 70%, proximal pole 20%, distal pole/tubercle 10% [2]

Clinical Significance

The importance of scaphoid fractures extends beyond the acute injury:

1. Non-union risk: 5-12% of appropriately treated waist fractures; up to 30% of proximal pole fractures [12,13]
2. AVN risk: Proximal pole fractures carry 30-40% risk; waist fractures 10-15% [4,14]
3. SNAC wrist arthritis: Develops in 95% of untreated non-unions over 10-15 years, causing chronic pain and disability [15]
4. Socioeconomic impact: Predominantly affects working-age males; average time off work 7-12 weeks for waist fractures [9]

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2. Anatomy and Pathophysiology

Gross Anatomy

The scaphoid (from Greek skaphos = "boat") is the largest bone in the proximal carpal row, measuring approximately 25mm in length. Unique among carpal bones, it is oriented obliquely across both proximal and distal carpal rows, articulating with:

• Radius (radial styloid and scaphoid fossa)
• Capitate (proximally)
• Lunate (medially via the scapholunate ligament)
• Trapezium and trapezoid (distally)

Approximately 80% of the scaphoid surface is covered in articular cartilage, limiting the available surface area for vascular foramina and creating a "bone at risk" for vascular compromise. [3] The bone can be anatomically divided into:

1. Proximal pole (25%)
2. Waist (middle third, 50%)
3. Distal pole and tubercle (25%)

Blood Supply: The Achilles' Heel

The precarious vascularity of the scaphoid, elegantly described by Gelberman and Menon in their seminal 1980 cadaveric injection study, is fundamental to understanding fracture complications. [3,4]

Arterial supply derives from the radial artery via two main systems:

1. Dorsal carpal branch (70-80% of intraosseous blood supply)

   • Enters through vascular foramina on the dorsal ridge at the waist
   • Supplies the proximal pole via retrograde flow (distal to proximal)
   • Branches form a dense intraosseous network in the distal two-thirds before ascending

2. Superficial palmar/volar branch (20-30% of supply)

   • Enters at the distal tubercle (volar surface)
   • Supplies only the distal pole and tubercle
   • Does not contribute to proximal pole vascularity

Critical clinical implications:

• A waist fracture disrupts the dorsal carpal vessels entering at the fracture site, isolating the proximal pole from its dominant blood supply
• The proximal pole has no alternative vascular supply—there are no intraosseous anastomoses connecting the dorsal and volar systems [3,4]
• The proximal pole is therefore entirely dependent on retrograde flow through the waist—fracture here creates a vascular "island"
• This explains the high AVN rates in proximal pole fractures (30-40%) compared to distal pole fractures (less than 1%) [14]

Exam Detail: Gelberman's Classification of Carpal Bone Vascularity:

Group I bones (scaphoid, capitate, 20% of lunates) have large areas dependent on a single intraosseous vessel without anastomoses—highest AVN risk. Group II bones (hamate, trapezoid) have dual entry points but no anastomoses—theoretical risk that rarely manifests clinically. Group III bones (trapezium, triquetrum, pisiform, 80% of lunates) have rich intraosseous anastomoses and dual entry points—lowest AVN risk. [16]

The time to revascularization following scaphoid fracture is prolonged compared to other fractures. MRI studies show bone marrow edema persisting 8-16 weeks in uncomplicated healing, and contrast enhancement studies demonstrate that complete revascularization of the proximal pole may take 4-6 months even with perfect anatomical reduction. [17]

Biomechanics and Fracture Mechanism

The scaphoid functions as the mechanical linchpin connecting the proximal row (intercalated segment) to the distal row (fixed to the metacarpals). During wrist motion:

• Wrist flexion and radial deviation: Scaphoid flexes (palmar tilt)
• Wrist extension and ulnar deviation: Scaphoid extends (dorsal tilt)

The typical mechanism of scaphoid fracture—hyperextension > 90° combined with radial deviation—creates several simultaneous forces: [11]

1. Compression force between the radial styloid and scaphoid tubercle
2. Bending moment creating tensile stress on the volar surface
3. Shear forces at the waist (narrowest point)

Biomechanical modeling demonstrates that peak stress concentrates at the scaphoid waist, explaining why 70% of fractures occur at this location. [11] The proximal pole is relatively protected unless associated with perilunate dislocation or direct axial loading.

Fracture Pathophysiology: Why Scaphoid Fractures Don't Heal

Several factors conspire against scaphoid fracture healing:

1. Tenuous blood supply: Proximal fragment ischemia in waist/proximal fractures
2. Synovial bathing: Intra-articular location allows synovial fluid to infiltrate the fracture site, inhibiting hematoma formation and osteogenesis
3. Constant motion: Even well-molded casts cannot completely immobilize the scaphoid due to its unique kinematics
4. Trabecular architecture: Predominantly trabecular bone heals more slowly than cortical bone
5. Carpal collapse tendency: Scaphoid fracture disrupts the lateral column, predisposing to flexion collapse (DISI deformity—see below)

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3. Classification Systems

Herbert Classification (Stability-Based)

The Herbert classification, introduced by Herbert and Fisher in 1984 alongside the Herbert screw, remains the most clinically relevant system as it predicts prognosis and guides treatment. [18]

Type A: Acute Stable Fractures

• A1: Tubercle fracture (distal pole) – excellent blood supply, benign prognosis
• A2: Incomplete waist fracture (hairline/cortical crack) – stable, low risk

Type B: Acute Unstable Fractures

• B1: Distal oblique fracture – inherently unstable due to shear forces
• B2: Complete waist fracture (displaced > 1mm) – high non-union risk
• B3: Proximal pole fracture – high AVN risk (30-40%)
• B4: Trans-scaphoid perilunate fracture-dislocation – high-energy injury, requires urgent reduction

Type C: Delayed Union

• Fracture present > 6 weeks with evidence of attempted healing but incomplete union

Type D: Non-Union

• D1: Fibrous non-union (stable, minimal sclerosis)
• D2: Sclerotic non-union (pseudarthrosis established)

Mayo Anatomic Classification

Simpler anatomic system based on fracture location:

1. Distal third (10%) – includes tubercle; excellent prognosis
2. Waist/middle third (70%) – standard prognosis; depends on displacement
3. Proximal pole (20%) – poor prognosis; high AVN risk

Cooney's Displacement Classification

• Type I: Non-displaced or minimally displaced (less than 1mm translation, less than 15° angulation)
• Type II: Displaced (> 1mm translation or > 15° angulation)

Clinical significance of displacement:

• Non-union rate less than 10% if non-displaced vs. 55% if displaced > 1mm [12]
• Scapholunate angle > 60° (normal 30-60°) indicates DISI instability and mandates surgery
• Lateral intrascaphoid angle > 35° (normal less than 15°) indicates "humpback deformity" and requires surgical correction [19]

Exam Detail: Radiographic angles to measure:

1. Scapholunate angle (lateral radiograph): Angle between lunate axis (perpendicular to line connecting volar and dorsal lunate horns) and scaphoid long axis. Normal 30-60°; > 60° indicates DISI (dorsal intercalated segment instability) pattern.

2. Intrascaphoid angle (lateral radiograph): Angle between proximal and distal scaphoid fragments. Normal less than 15°; > 35° indicates humpback deformity with flexion of distal fragment.

3. Lunocapitate angle (lateral radiograph): Angle between lunate and capitate axes. Normal -15° to +15°; > 15° dorsal indicates DISI.

These measurements are critical for surgical planning and prognostic counseling—humpback deformity > 35° that heals in malposition results in permanent loss of wrist extension averaging 25-30°. [19]

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4. Clinical Presentation

Patient Demographics and History

Typical presentation:

• Male, aged 20-35 years
• Mechanism: Fall onto outstretched hand (FOOSH), often during sports (rugby, football, skateboarding, snowboarding)
• Timing: May present acutely (day of injury) or delayed (1-2 weeks later when pain persists)
• Symptoms: Dull, aching pain over radial wrist; reduced grip strength; difficulty weight-bearing on hand

Red flag histories:

• High-energy mechanism (motor vehicle accident, fall from height) → consider perilunate dislocation
• Previous scaphoid injury → may represent delayed presentation of non-union
• Chronic symptoms > 6 weeks → suspect delayed union or established non-union

Clinical Examination

Systematic scaphoid examination protocol:

1. Inspection

   • Swelling over radial wrist (often subtle)
   • Deformity (rare; indicates displacement or perilunate dislocation)
   • Position: wrist held in slight extension

2. Palpation—Four cardinal tests

   a) Anatomical snuffbox tenderness (Most sensitive test)

   • Technique: Patient extends and radially deviates thumb; palpate depression between EPL and EPB/APL tendons
   • Sensitivity: 90-100% (highly sensitive—negative test effectively rules out fracture) [20]
   • Specificity: 40-50% (limited—many false positives from soft tissue injury, radial nerve, de Quervain's tenosynovitis) [20]

   b) Scaphoid tubercle tenderness (Most specific test)

   • Technique: Palpate volar aspect of radial wrist at distal wrist crease, just ulnar to FCR tendon
   • Sensitivity: 82-87%
   • Specificity: 80-96% (highly specific—positive test strongly suggests fracture) [20]

   c) Axial compression test (Scaphoid compression test)

   • Technique: Compress thumb along its long axis toward radius ("telescoping" the thumb)
   • Sensitivity: 82-100%
   • Specificity: 65-85%

   d) Resisted pronation/supination (Torque test)

   • Technique: Patient makes fist; examiner resists pronation and supination of forearm
   • Pain suggests scaphoid fracture (transmitted forces through radiocarpal joint)

3. Range of motion

   • Reduced wrist extension (normal 70°; may reduce to 40-50° acutely)
   • Reduced radial deviation (normal 20°; often markedly reduced)
   • Grip strength: typically 40-60% of contralateral side [9]

4. Neurovascular examination

   • Radial pulse, capillary refill, sensation in radial nerve distribution (first web space)
   • Median nerve (carpal tunnel): exclude acute carpal tunnel syndrome from hematoma/swelling

Clinical Pearls

"Snuffbox is Sensitive, Tubercle is Specific": Use snuffbox tenderness as a screening test (high sensitivity rules out), and tubercle tenderness as a confirmatory test (high specificity rules in). Combining both tests increases diagnostic accuracy to > 90%. [20]

"The Missed Scaphoid": Approximately 20-25% of scaphoid fractures are radiographically occult on initial presentation. A normal radiograph in a patient with snuffbox tenderness does NOT exclude fracture. MRI or empirical immobilization with reassessment is mandatory. [5,6,8]

"Bilateral examination": Always examine the contralateral wrist. Some patients have constitutional snuffbox tenderness or anatomical variations that can lead to false positives.

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5. Differential Diagnosis

Must-Not-Miss Diagnoses

1. Perilunate/lunate dislocation

   • High-energy mechanism
   • Gross swelling and deformity
   • Requires urgent reduction (median nerve compromise)
   • Look for "spilled teacup" sign on lateral radiograph

2. Trans-scaphoid perilunate fracture-dislocation (Herbert B4)

   • Scaphoid fracture + carpal dislocation
   • Requires urgent ORIF + ligament repair

3. Distal radius fracture

   • More common in elderly
   • Often obvious on radiograph
   • Can coexist with scaphoid fracture (5-10% of Colles fractures)

Common Mimics

4. De Quervain's tenosynovitis

   • Pain over radial styloid
   • Positive Finkelstein test (thumb flexed into palm, wrist ulnar deviation)
   • Tenderness over 1st dorsal compartment (APL/EPB), not scaphoid tubercle

5. Scapholunate ligament injury

   • Often coexists with scaphoid fracture
   • Watson's scaphoid shift test positive
   • Scapholunate gap > 3mm on PA radiograph (Terry Thomas sign)

6. Radial styloid fracture (Chauffeur's fracture)

   • Visible on PA radiograph
   • Tenderness directly over styloid tip

7. 1st CMC joint arthritis (Basal thumb arthritis)

   • Chronic onset, older age group
   • Tenderness at thumb base, not snuffbox
   • "Grind test" positive (axial load + rotation of thumb metacarpal)

8. Scaphoid non-union (presenting as "new" injury)

   • Previous injury often forgotten
   • Chronic symptoms
   • Sclerosis, cyst formation on radiograph

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6. Investigations

First-Line Imaging: Scaphoid Radiograph Series

Standard scaphoid series (4 views):

1. PA (Posteroanterior): Hand flat, pronated
2. Lateral: True lateral of wrist
3. Oblique: 45° pronation (profile view of scaphoid)
4. Scaphoid view (Ziter view/PA with ulnar deviation): Hand ulnar deviated 20-30°, tube angled 20° proximally—elongates and profiles the scaphoid waist

Radiographic signs of scaphoid fracture:

• Cortical break (most reliable)
• Trabecular disruption
• Sclerosis (delayed presentation/non-union)
• Fracture line (may be subtle or absent acutely)

Sensitivity of initial radiographs: 70-80% [5,6]

• 15-25% of genuine scaphoid fractures are radiographically occult initially
• Repeat radiographs at 10-14 days may reveal fracture (due to bone resorption at fracture margins increasing visibility), but MRI is now preferred to avoid unnecessary immobilization

Gold Standard: MRI

Indications for MRI:

• Clinical suspicion of scaphoid fracture (positive examination) + normal radiographs
• Equivocal radiographic findings

Protocol:

• Should be performed within 24-72 hours of injury [8]
• T1-weighted: shows fracture line as low signal
• T2-weighted/STIR: shows bone marrow edema as high signal

MRI performance:

• Sensitivity: 95-100%
• Specificity: 90-100%
• Negative predictive value: ~100% [7,8]

Clinical impact: A 2024 multicentre UK study (n=1,989 patients with suspected scaphoid fracture) found that early MRI detected occult fractures in 12.9% of cases, while avoiding unnecessary immobilization in 87% of patients with negative MRI. [8] Importantly, 6.3% of MRI-detected fractures still developed delayed union or non-union despite appropriate cast treatment, confirming that occult fractures are not universally benign. [8]

MRI vs. CT for acute diagnosis:

• MRI superior for detecting acute fractures (shows bone marrow edema even without cortical fracture)
• CT detects only established cortical/trabecular fractures; sensitivity ~70-85% acutely
• CT role is primarily for union assessment and surgical planning, not acute diagnosis

CT Scanning

Indications:

1. Union assessment at 8-12 weeks (gold standard for confirming bony union)
2. Surgical planning (displacement measurement, angulation, humpback deformity)
3. Non-union assessment (sclerosis, cyst formation, carpal collapse)

CT findings of union:

• Bridging trabeculae across fracture site (in ≥50% of cross-sectional area)
• Absence of fracture line on all planes

CT findings of non-union:

• Persistent fracture line
• Sclerosis of fragment margins
• Cyst formation
• Humpback deformity (intrascaphoid angle > 35°)

Ultrasound

Emerging modality for occult fracture diagnosis:

• Pooled sensitivity: 85.6%; specificity: 83.3% [21]
• Main finding: cortical disruption on dorsal or volar surface
• Advantages: Low cost, no radiation, immediate availability
• Disadvantages: Operator-dependent; may miss undisplaced fractures
• Current role: Limited; MRI remains gold standard, but ultrasound may have a role in resource-limited settings when MRI/CT unavailable [21]

Bone Scintigraphy (Historical)

• Now largely replaced by MRI
• High sensitivity (96-100%) but poor specificity (60-80%)—cannot differentiate fracture from bone bruising, soft tissue injury
• Requires 48-72 hours post-injury for uptake
• Radiation exposure
• Essentially obsolete for scaphoid fracture diagnosis in modern practice

Exam Detail: When is follow-up imaging needed in conservatively treated fractures?

Standard protocol:

1. Week 0: Scaphoid radiograph series (initial diagnosis)
2. Week 6: Clinical review + radiographs (if clinically healed, consider reducing immobilization)
3. Week 10-12: CT scan to confirm union (gold standard)

Distal pole fractures: May unite at 6 weeks Waist fractures: Typically require 8-12 weeks Proximal pole fractures: May require 12-20 weeks

Definition of clinical union: No snuffbox tenderness, full grip strength, full range of motion Definition of radiographic union: Bridging trabeculae on CT in > 50% of cross-sectional area

If non-union suspected at 12 weeks (persistent fracture line on CT, ongoing pain), refer for surgical assessment.

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7. Management

Management of scaphoid fractures has evolved significantly following the SWIFFT trial (2020), which provided Level I evidence comparing surgical fixation to cast immobilization for undisplaced waist fractures. [9]

Initial Emergency Department Management

All patients with clinical suspicion of scaphoid fracture:

1. Immobilization

   • Apply below-elbow backslab or scaphoid-type splint
   • Position: Wrist in neutral to slight extension (glass-holding position), thumb included
   • Do not discharge with reassurance alone if examination positive

2. Imaging

   • Scaphoid radiograph series (4 views)
   • If normal radiographs but positive examination → arrange MRI within 24-72 hours OR immobilize and review in fracture clinic

3. Analgesia

   • Simple analgesia (paracetamol, NSAIDs if not contraindicated)
   • Avoid opioids in simple scaphoid fractures

4. Safety-netting

   • Advise patient to return if increasing pain, swelling, neurovascular symptoms
   • Provide written information

Decision Algorithm

SCAPHOID FRACTURE CONFIRMED
         ↓
   ASSESS STABILITY
         ↓
    ┌─────────┴─────────┐
  STABLE              UNSTABLE
  (Herbert A1/A2)     (Herbert B1-B4)
         ↓                    ↓
   Non-displaced      Displaced > 1mm
   Waist fracture        OR
   Distal fracture    Proximal pole
   No angulation         OR
                      Perilunate FD
         ↓                    ↓
   CONSERVATIVE        SURGICAL FIXATION
   Below-elbow cast    (Immediate ORIF)
   8-12 weeks              ↓
         ↓              Herbert screw
   CT at 12 weeks      Dorsal/volar approach
         ↓                    ↓
    ┌────┴────┐        Follow-up imaging
  UNION    NON-UNION   Union expected 12 wk
    ↓          ↓
  Mobilise  Surgery
            (Graft)

Conservative (Non-Operative) Management

Indications (following SWIFFT trial): [9]

• Undisplaced (less than 1mm translation, less than 15° angulation) waist fractures
• Distal pole/tubercle fractures (Herbert A1)
• Incomplete/hairline waist fractures (Herbert A2)
• Patient preference after informed discussion

Immobilization protocol:

Cast type: Below-elbow cast (Colles-type) is sufficient

• SWIFFT trial and meta-analyses confirm: no difference in union rates between below-elbow, above-elbow, or thumb spica casts [9,22]
• Modern standard: Below-elbow cast, thumb to IP joint included
• Position: Wrist neutral to 10° extension, forearm neutral rotation
• "Glass-holding position"

Duration:

• Distal pole: 4-6 weeks
• Waist: 8-12 weeks (median 10 weeks to union)
• Proximal pole: Conservative management controversial; if attempted, 12-16 weeks (high failure rate)

Follow-up schedule:

1. Week 2: Check cast, review MRI if awaited
2. Week 6: Clinical assessment ± radiographs
3. Week 10-12: CT scan to confirm union (mandatory—clinical assessment alone unreliable)
4. If united: Mobilization, hand therapy
5. If non-union: Surgical referral

Outcomes of conservative management (SWIFFT trial): [9]

• Union rate: 91% for undisplaced waist fractures
• Mean PRWE score at 52 weeks: 14.0 points (excellent—score less than 25 considered asymptomatic)
• Non-union requiring surgery: 9%
• Time to union: Mean 10 weeks (range 6-16 weeks)

Surgical Management

Indications:

Absolute indications:

1. Displaced fractures (> 1mm translation or > 15° angulation)
2. Proximal pole fractures (high AVN risk—30-40%)
3. Trans-scaphoid perilunate fracture-dislocation (Herbert B4)
4. Delayed union (> 6 months, no evidence of healing)
5. Established non-union
6. Humpback deformity (intrascaphoid angle > 35°)

Relative indications: 7. High-demand athletes/laborers (faster return to activity—though SWIFFT showed minimal advantage) 8. Patient preference (after informed consent about risks) 9. Bilateral fractures (to allow one hand to be mobile during healing)

Surgical techniques:

Percutaneous Screw Fixation

Indications: Undisplaced or minimally displaced waist fractures (patient preference/athletic demands)

Approach: Volar percutaneous (most common)

• Small incision over scaphoid tubercle
• Guidewire insertion under fluoroscopy
• Cannulated Herbert screw insertion
• Advantages: Minimal soft tissue dissection, preserves blood supply
• Disadvantages: Cannot reduce displaced fragments; risk of malposition

Implant: Herbert screw (headless compression screw)

• Variable pitch threads: distal threads have smaller pitch than proximal
• As screw advances, creates interfragmentary compression
• Headless design allows complete burial (no prominence)

Outcomes:

• Union rate: 94-97%
• Time to union: 8-12 weeks (similar to conservative treatment)
• Return to sports: 6-8 weeks (vs. 12 weeks with cast—marginal benefit)
• Complications: Screw prominence (5-8%), malposition (3-5%), AVN from surgical trauma (1-2%) [9]

Open Reduction Internal Fixation (ORIF)

Indications: Displaced fractures, proximal pole fractures, non-unions

Surgical approaches:

a) Volar approach (Russe/FCR approach)

• Indication: Waist and distal pole fractures
• Incision: Along FCR tendon
• Advantages: Preserves dorsal blood supply entering at waist; allows volar tilt correction
• Disadvantages: Cannot address proximal pole fractures adequately
• Approach of choice for waist fractures requiring ORIF

b) Dorsal approach

• Indication: Proximal pole fractures, humpback deformity correction
• Incision: Between 3rd and 4th dorsal compartments
• Advantages: Direct access to proximal pole; optimal screw trajectory (central axis alignment)
• Disadvantages: Disrupts dorsal blood supply (accept this trade-off for better fixation)
• Approach of choice for proximal pole fractures

Fixation: Herbert screw or alternative (cannulated compression screw, dorsal plate if severe comminution)

Bone Grafting for Non-Unions

Indications:

• Established non-union (> 6 months)
• Non-union with AVN
• Non-union with humpback deformity

Graft options:

1. Non-vascularized corticocancellous graft (Matti-Russe procedure)

• Indication: Fibrous non-union without AVN, viable bone both fragments
• Source: Iliac crest or distal radius
• Technique: Excavate non-union, pack with cancellous graft, fix with screw
• Union rate: 85-92% [23]

2. Vascularized bone graft

• Indication: Proximal pole AVN, previous failed non-vascularized graft, sclerotic non-union
• Sources:
  • 1,2-ICSRA (1st/2nd intercompartmental supraretinacular artery from distal radius)—most common
  • Medial femoral condyle pedicled graft
• Union rate: 88-94% in AVN cases [14,23]

Controversy: A 2019 systematic review found no clear superiority of vascularized over non-vascularized grafts even in AVN cases, though vascularized grafts are theoretically superior. [23] High-quality comparative trials are lacking.

Special Considerations

Proximal pole fractures:

• High-risk fracture (AVN 30-40%, non-union 30%)
• Most surgeons advocate primary surgical fixation (not included in SWIFFT trial)
• Dorsal approach preferred (allows central screw placement)
• Consider prophylactic bone grafting even in acute setting (debated)

Perilunate fracture-dislocation (Herbert B4):

• Surgical emergency (reduce within 24 hours to minimize AVN and median nerve injury)
• Combined volar and dorsal approach often required
• ORIF scaphoid + carpal ligament repair + K-wire stabilization of carpal alignment
• Prognosis guarded: 30-40% develop post-traumatic arthritis long-term

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8. Complications

Non-Union

Definition: Failure of fracture to unite by 6 months despite appropriate treatment

Incidence:

• Undisplaced waist fractures (conservative): 5-10% [12]
• Displaced fractures (without surgery): 50-55% [12]
• Proximal pole fractures: 30-40% [13]

Risk factors for non-union:

1. Displacement > 1mm (strongest predictor—OR 5.5)
2. Proximal pole location (watershed blood supply)
3. Delayed diagnosis/treatment > 4 weeks
4. Smoking (vasoconstriction impairs healing)
5. Instability patterns (DISI, humpback deformity)
6. Inadequate immobilization (non-compliance, cast slippage)

Clinical presentation:

• Chronic dull radial wrist pain (may be minimal initially—"painless non-union")
• Reduced grip strength (typically 60-70% of contralateral)
• Clicking/clunking with wrist motion
• May be asymptomatic for years before arthritis develops

Radiographic features:

• Persistent fracture line
• Sclerosis of fragment margins
• Cyst formation within fragments
• Humpback deformity (flexion of distal fragment)

Management:

• Surgical repair mandatory (even if asymptomatic—prevents SNAC arthritis)
• ORIF + bone graft (vascularized if AVN, non-vascularized if viable bone)
• Union rate after grafting: 85-95%

Avascular Necrosis (AVN)

Definition: Ischemic death of scaphoid bone (typically proximal pole) due to disrupted blood supply

Incidence:

• Waist fractures: 10-15%
• Proximal pole fractures: 30-40% [4,14]

Pathophysiology:

• Fracture disrupts dorsal carpal vessels entering at waist
• Proximal pole isolated from blood supply (no intraosseous anastomoses)
• Time-dependent: AVN develops over 3-6 months post-injury
• Proximal fragment undergoes osteocyte death → revascularization → creeping substitution → collapse

Radiographic findings:

• Increased density of proximal pole ("white proximal pole")—classical sign (due to relative density compared to osteopenic viable bone, plus microfracture collapse)
• Collapse of proximal pole architecture
• Preserved distal fragment

MRI findings:

• T1: Low signal in proximal pole (diagnostic)
• T2: Variable signal
• Contrast-enhanced: Absence of enhancement in proximal pole (confirms AVN)

Management:

• If detected early (pre-collapse): Vascularized bone graft + screw fixation
• If collapsed: Salvage procedures (see below)
• Success rate: Union achievable in 85-90% with vascularized grafting [14]

SNAC Wrist (Scaphoid Non-Union Advanced Collapse)

Definition: Predictable pattern of progressive post-traumatic osteoarthritis following scaphoid non-union

Epidemiology:

• Develops in 95% of untreated scaphoid non-unions over 10-15 years [15]
• Inevitable progression (only timing varies)

Pathophysiology:

• Scaphoid non-union → loss of lateral carpal column support
• Proximal fragment extends, distal fragment flexes (humpback)
• Capitate migrates proximally between scaphoid fragments
• Abnormal load transmission → cartilage degeneration → arthritis

SNAC staging (Watson and Ballet):

Key feature: The radiolunate joint is preserved until Stage IV (late). This preservation allows motion-sparing salvage procedures (PRC, 4-corner fusion) to succeed.

Clinical presentation:

• Chronic wrist pain (initially activity-related, then constant)
• Stiffness (progressive loss of extension and radial deviation)
• Reduced grip strength (50-60% of normal)
• Crepitus with wrist motion
• Swelling over radial wrist

Imaging:

• Radiographs: Joint space narrowing, subchondral sclerosis, osteophytes
• CT: Defines extent of cartilage loss; surgical planning
• MRI: Not typically needed (diagnosis clinical + radiographic)

Management:

• Stage I: Radial styloidectomy + scaphoid ORIF + bone graft (if viable)
• Stage II-III: Proximal row carpectomy (PRC) vs. 4-corner fusion (scaphoid excision + fusion of capitate-hamate-lunate-triquetrum)
• Debate continues regarding PRC vs. 4CF—recent systematic review (2025) found no significant difference in outcomes between procedures, regardless of SNAC vs. SLAC etiology [15]
• Stage IV: Total wrist arthrodesis (fusion) or wrist replacement arthroplasty (limited role)

Exam Detail: PRC vs. 4-Corner Fusion: Evidence and Selection

Proximal Row Carpectomy (PRC):

• Concept: Remove scaphoid, lunate, triquetrum; capitate articulates directly with lunate fossa of radius
• Advantages: Simpler procedure; faster recovery; no non-union risk (no fusion required); preserves ~50-60% wrist motion
• Disadvantages: Potential for arthrosis of capitolunate joint long-term; less pain relief in some studies; requires intact cartilage on capitolunate joint
• Long-term: Good outcomes at 10 years in 70-80%; revision to fusion in 10-15%

4-Corner Fusion (4CF):

• Concept: Excise scaphoid; fuse capitate-hamate-lunate-triquetrum; radius articulates with fused midcarpal unit
• Advantages: More predictable pain relief; greater load-bearing capacity; better grip strength in some studies
• Disadvantages: Non-union risk (5-10%); more complex surgery; preserves only ~40-50% wrist motion; hardware complications (plate prominence)
• Long-term: Good outcomes 75-85% at 10 years

Current evidence (2025 systematic review): No statistically significant difference in pain, ROM, DASH scores, or complication rates between PRC and 4CF for SNAC wrist. [15] Selection typically based on surgeon preference and patient factors (activity demands, capitolunate cartilage integrity).

Malunion (Humpback Deformity)

Definition: Fracture heals in flexed position, creating humpback contour (distal fragment flexed, proximal fragment extended)

Incidence: 10-15% of displaced fractures treated conservatively

Pathophysiology:

• Loss of scaphoid length + flexion angulation → distal carpal row translates proximally
• Capitate migrates proximally (carpal collapse)
• Compensatory DISI deformity (dorsal intercalated segment instability—lunate extends)

Clinical consequence:

• Loss of wrist extension (average 25-30° reduction—patients cannot perform push-ups, weight-bearing on hand)
• Radial deviation limited
• Early SNAC arthritis (abnormal joint loading)

Imaging:

• Lateral radiograph: Increased intrascaphoid angle > 35° (normal less than 15°)
• Scapholunate angle > 60° (DISI pattern)

Management:

• Acute detection (before union): Surgical correction mandatory—ORIF + bone graft to restore length + correct angulation
• Established malunion: Scaphoid osteotomy + wedge bone graft + fixation (complex; not always successful)

Other Complications

Surgical complications:

• Screw prominence: 5-8% (may require removal)
• Infection: less than 1% (low with modern technique)
• Nerve injury: Superficial radial nerve neuropraxia 2-3% (usually transient)
• Iatrogenic AVN: 1-2% (from surgical devascularization)
• Malposition of screw: 3-5% (may not achieve compression)

Cast complications (from SWIFFT trial): [9]

• Skin problems (pressure sores, contact dermatitis): 15-18%
• Stiffness requiring prolonged physiotherapy: 8-10%
• Complex regional pain syndrome (CRPS): less than 1%

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9. Prognosis and Outcomes

Healing Time by Fracture Location

Functional Outcomes (SWIFFT Trial Data, 52-Week Follow-Up)

Conservative management (cast): [9]

• PRWE score: 14.0 (excellent—less than 25 considered minimal disability)
• Grip strength: 92% of contralateral hand
• Range of motion: 88% of contralateral wrist
• Return to full activity: Median 12 weeks
• Patient satisfaction: 89% "satisfied" or "very satisfied"

Surgical management (immediate fixation): [9]

• PRWE score: 11.9 (no statistically significant difference from cast, p=0.27)
• Grip strength: 94% of contralateral hand (not significantly different)
• Range of motion: 90% of contralateral wrist (not significantly different)
• Return to full activity: Median 10 weeks (slightly faster, but marginal)
• Patient satisfaction: 87% (not significantly different)

Conclusion from SWIFFT: For undisplaced scaphoid waist fractures, cast immobilization achieves equivalent functional outcomes to surgery at 1 year, with fewer complications and lower cost. Surgery reserved for displaced fractures, proximal pole fractures, or patient preference after informed discussion. [9]

Prognostic Factors for Poor Outcome

Factors predicting non-union/AVN:

1. Displacement > 1mm (strongest predictor)
2. Proximal pole location
3. Delayed treatment > 4 weeks
4. Smoking
5. High-energy mechanism (associated injuries)

Factors predicting good outcome:

1. Early diagnosis and treatment
2. Undisplaced fracture
3. Distal pole location
4. Patient compliance with immobilization
5. Young age (less than 30 years)

Long-Term Outcomes

5-10 year follow-up studies:

• Successfully united fractures: 85-90% excellent outcomes; 5-10% develop mild arthritis (usually asymptomatic)
• Non-union (treated surgically with graft): 70-80% good-excellent outcomes; 15-20% progress to SNAC despite union
• SNAC wrist (salvage procedures): 70-80% achieve satisfactory pain relief and function; 10-15% require revision to total wrist fusion

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10. Prevention and Patient Education

Primary Prevention

Risk reduction strategies:

• Protective wrist guards for high-risk sports (snowboarding, skateboarding, rollerblading)
• Fall prevention strategies in elderly
• Workplace safety training (manual laborers)

Secondary Prevention (Preventing Complications)

Patient education for diagnosed scaphoid fractures:

1. Importance of immobilization compliance

   • Explain AVN and non-union risks if non-compliant
   • Keep cast dry and intact
   • Attend all follow-up appointments

2. Activity modification

   • No contact sports, heavy lifting, or impact activities until union confirmed
   • Office work/light duties may continue if wrist protected

3. Smoking cessation

   • Evidence: Smoking increases non-union risk 2-3 fold
   • Refer to smoking cessation services

4. Recognition of complications

   • Increasing pain (infection, cast pressure, CRPS)
   • Numbness/tingling (median nerve compression, compartment syndrome)
   • Cast problems (wet, loose, tight)

Patient Explanation Scripts

"Why is this fracture serious?" "The scaphoid bone is like a keystone in an arch—it holds the wrist together. It also has a poor blood supply, like a bridge with only one road to it. If the fracture blocks that road, part of the bone can die, which causes long-term arthritis. That's why we take these fractures very seriously, even when they look small."

"Why do I need a cast for so long?" "Because the blood flow to the scaphoid is slow, it takes 10-12 weeks to heal—double the time of a normal wrist fracture. If we remove the cast too early, the bone stops healing and forms a non-union, which eventually needs surgery. We'll do a CT scan at 12 weeks to check if the bone has healed properly before removing the cast."

"Why didn't it show on the X-ray?" "Scaphoid fractures are tricky—about 1 in 4 don't show up on the first X-ray because the fracture crack is too small to see. That's why we use an MRI scan if we're suspicious. The MRI can see bruising inside the bone, which tells us if there's a fracture even before it becomes visible on X-ray."

"Do I need surgery?" "For most scaphoid fractures, a cast works just as well as surgery. A large study (the SWIFFT trial) showed that patients treated with a cast had the same outcomes at 1 year as those who had surgery, but with fewer complications. We reserve surgery for fractures that are displaced (misaligned), at the top of the bone (poor blood supply), or if you're an elite athlete who needs to return to sport quickly. For your fracture, we recommend a cast."

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11. Key Guidelines and Evidence

Major Clinical Trials

1. SWIFFT Trial (Dias et al., 2020) [9]
   • Design: Multicentre RCT, n=439, UK/Wales, 31 hospitals
   • Comparison: Surgery (immediate Herbert screw) vs. Cast immobilization (with early fixation of non-unions)
   • Population: Adults with bicortical scaphoid waist fractures displaced ≤2mm
   • Primary outcome: PRWE score at 52 weeks
   • Results: No significant difference (Surgery 11.9 vs. Cast 14.0, p=0.27)
   • Complications: Surgery group 14% serious complications vs. Cast 1%
   • Conclusion: Cast immobilization is first-line for undisplaced waist fractures
   • Impact: Changed practice worldwide; reduced surgical fixation rates

Society Guidelines

British Orthopaedic Association (BOA) / British Society for Surgery of the Hand (BSSH):

• MRI within 24-72 hours for suspected scaphoid with negative radiographs
• Below-elbow cast sufficient (thumb spica not mandatory)
• CT at 12 weeks to confirm union
• Surgery for displaced (> 1mm), proximal pole, or failed conservative treatment

American Academy of Orthopaedic Surgeons (AAOS):

• Similar recommendations
• Strong evidence supporting MRI for occult fractures
• Moderate evidence supporting conservative management for undisplaced fractures

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12. Examination Focus and Viva Preparation

Common MRCS/FRCS Viva Questions

Q1: "Describe the blood supply to the scaphoid and explain its clinical significance."

Model answer: "The scaphoid receives 70-80% of its blood supply from the dorsal carpal branch of the radial artery, which enters through vascular foramina on the dorsal ridge at the waist. This supplies the proximal pole via retrograde flow—meaning blood flows from distal to proximal. The remaining 20-30% comes from the superficial palmar branch supplying the distal tubercle. The clinical significance is that a waist fracture disrupts the dorsal supply to the proximal pole, which has no alternative blood supply. This creates a vascular 'watershed' zone, explaining the high risk of avascular necrosis in proximal pole fractures—approximately 30-40%. Gelberman's cadaveric studies classified the scaphoid as a Group I bone with areas dependent on a single vessel, making it highly vulnerable to AVN." [3,4,16]

Q2: "A 25-year-old man presents to ED with wrist pain after a fall. Examination reveals snuffbox tenderness but radiographs are normal. What is your management?"

Model answer: "Despite normal radiographs, 20-25% of scaphoid fractures are occult on initial imaging. Given the positive clinical examination, I would not discharge the patient with reassurance alone. My management would be: First, immobilize the wrist in a below-elbow backslab including the thumb. Second, arrange an urgent MRI within 24-72 hours—this is the gold standard for detecting occult fractures with 95-100% sensitivity. If MRI confirms a fracture, I would initiate definitive treatment based on fracture stability. If MRI is negative, the cast can be removed and the patient mobilized immediately, avoiding unnecessary immobilization. This is supported by the 2024 multicentre UK study showing early MRI avoided unnecessary immobilization in 87% of suspected scaphoid fractures." [7,8]

Q3: "What are the stages of SNAC wrist and how would you manage each stage?"

Model answer: "SNAC wrist—Scaphoid Non-union Advanced Collapse—is the predictable pattern of post-traumatic arthritis following scaphoid non-union, occurring in 95% of cases over 10-15 years. The key feature is that the radiolunate joint is preserved until late stages.

Stage I affects the radial styloid-scaphoid articulation. Management is radial styloidectomy with attempted ORIF and bone grafting of the scaphoid if viable.

Stage II involves the entire radioscaphoid fossa. The radiolunate joint is still preserved. Management options are proximal row carpectomy or scaphoid excision with 4-corner fusion.

Stage III involves the capitolunate joint but the radiolunate joint remains preserved. Management is either proximal row carpectomy or 4-corner fusion—a 2025 systematic review found no significant difference in outcomes between these procedures.

Stage IV is rare pan-carpal arthritis including the radiolunate joint. This requires total wrist arthrodesis as the only reliable salvage procedure.

Motion-preserving procedures work in Stages II-III specifically because the radiolunate joint is preserved, allowing the capitate to articulate with the lunate fossa after proximal row carpectomy." [15]

Q4: "What evidence guides your choice between surgical and conservative management of scaphoid waist fractures?"

Model answer: "The SWIFFT trial, published in The Lancet in 2020, provides Level I evidence. This pragmatic multicentre RCT randomized 439 adults with bicortical scaphoid waist fractures displaced ≤2mm to either immediate surgical fixation with a Herbert screw or below-elbow cast immobilization with early fixation of any non-unions. At 52-week follow-up, there was no significant difference in the primary outcome—PRWE scores were 11.9 in the surgery group versus 14.0 in the cast group, p=0.27. Functional outcomes including grip strength and range of motion were equivalent. However, serious complications occurred in 14% of the surgery group versus only 1% in the cast group. The conclusion is that undisplaced waist fractures should be treated with initial cast immobilization, reserving surgery for displaced fractures, proximal pole fractures, or patient preference after informed discussion. This has changed practice worldwide, reducing surgical fixation rates significantly." [9]

Q5: "Describe the Herbert classification of scaphoid fractures."

Model answer: "The Herbert classification is stability-based and guides treatment. It divides fractures into four types:

Type A are acute stable fractures: A1 is a tubercle fracture with excellent prognosis, and A2 is an incomplete or hairline waist fracture.

Type B are acute unstable fractures: B1 is a distal oblique fracture unstable due to shear forces; B2 is a complete displaced waist fracture with high non-union risk; B3 is a proximal pole fracture with 30-40% AVN risk; and B4 is a trans-scaphoid perilunate dislocation requiring urgent surgery.

Type C is delayed union—a fracture present more than 6 weeks with incomplete healing.

Type D is established non-union: D1 is fibrous non-union and D2 is sclerotic non-union with pseudarthrosis.

The classification is clinically useful because Type A fractures can typically be managed conservatively, while Type B fractures generally require surgical fixation." [18]

Common Clinical Mistakes to Avoid

❌ Mistake 1: Discharging a patient with snuffbox tenderness and normal radiographs without immobilization or MRI

• Consequence: Missed occult fracture → delayed diagnosis → non-union → SNAC wrist
• Correct approach: MRI within 24-72 hours OR immobilize and review

❌ Mistake 2: Treating all scaphoid fractures surgically

• Consequence: Unnecessary surgery, increased complications, higher cost
• Correct approach: SWIFFT trial supports conservative management for undisplaced waist fractures

❌ Mistake 3: Relying on clinical examination or radiographs alone to confirm union

• Consequence: Premature mobilization → non-union
• Correct approach: CT scan at 12 weeks is gold standard for union confirmation

❌ Mistake 4: Using above-elbow casts or rigid thumb spica for all scaphoid fractures

• Consequence: Unnecessary immobilization, patient discomfort, elbow stiffness
• Correct approach: Below-elbow cast with thumb to IP joint is sufficient

❌ Mistake 5: Assuming MRI-detected occult fractures are always benign

• Consequence: Inadequate follow-up → missed non-union
• Correct approach: 6.3% of MRI-detected fractures still develop delayed/non-union despite treatment; appropriate immobilization and CT follow-up mandatory [8]

Examination Tips

For clinical examination stations (OSCE/PACES):

1. Always examine both wrists (comparison aids detection of subtle abnormalities)
2. Perform all four palpation tests (snuffbox, tubercle, axial compression, resisted pronation)
3. Document neurovascular status (exclude compartment syndrome, median nerve injury)
4. State your imaging request explicitly: "Scaphoid series radiographs with PA, lateral, oblique, and ulnar deviation views"

For viva/oral examination:

1. Start with the blood supply—this is asked in 80% of scaphoid vivas
2. Quote the SWIFFT trial—demonstrates evidence-based practice
3. Distinguish stable vs. unstable (Herbert classification)
4. Know the SNAC staging—commonly asked
5. Be able to draw the management algorithm (clear decision tree shows systematic thinking)

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13. References

1. Duckworth AD, et al. The epidemiology of fractures of the scaphoid: impact of age, gender, deprivation and seasonality. Bone Joint J. 2012;94-B(9):1299-304. doi:10.1302/0301-620X.94B9.28668

2. Almigdad A, et al. A review of scaphoid fracture, treatment outcomes, and consequences. Int Orthop. 2024;48(2):529-536. doi:10.1007/s00264-023-06014-2

3. Gelberman RH, Menon J. The vascularity of the scaphoid bone. J Hand Surg Am. 1980;5(5):508-13. doi:10.1016/s0363-5023(80)80087-6

4. Panagis JS, Gelberman RH, Taleisnik J, Baumgaertner M. The arterial anatomy of the human carpus. Part II: The intraosseous vascularity. J Hand Surg Am. 1983;8(4):375-82. doi:10.1016/s0363-5023(83)80195-6

5. Phillips TG, Reibach AM, Slomiany WP. Diagnosis and management of scaphoid fractures. Am Fam Physician. 2004;70(5):879-84.

6. Suh N, Grewal R. Controversies and best practices for acute scaphoid fracture management. J Hand Surg Eur Vol. 2018;43(1):4-12. doi:10.1177/1753193417735973

7. Kwee RM, Kwee TC. Ultrasound for diagnosing radiographically occult scaphoid fracture. Skeletal Radiol. 2018;47(9):1205-1212. doi:10.1007/s00256-018-2931-7

8. Dean BJF, et al. The rate of nonunion in the MRI-detected occult scaphoid fracture. Bone Joint J. 2024;106-B(4):387-393. doi:10.1302/0301-620X.106B4.BJJ-2023-1171.R1

9. Dias JJ, Brealey SD, Fairhurst C, et al. Surgery versus cast immobilisation for adults with a bicortical fracture of the scaphoid waist (SWIFFT): a pragmatic, multicentre, open-label, randomised superiority trial. Lancet. 2020;396(10248):390-401. doi:10.1016/S0140-6736(20)30931-4

10. van Tassel DC, Owens BD, Wolf JM. Incidence estimates and demographics of scaphoid fracture in the U.S. population. J Hand Surg Am. 2010;35(8):1242-5. doi:10.1016/j.jhsa.2010.05.017

11. Weber ER, Chao EY. An experimental approach to the mechanism of scaphoid waist fractures. J Hand Surg Am. 1978;3(2):142-8. doi:10.1016/s0363-5023(78)80061-0

12. McQueen MM, Gelbke MK, Wakefield A, Will EM, Gaebler C. Percutaneous screw fixation versus conservative treatment for fractures of the waist of the scaphoid: a prospective randomised study. J Bone Joint Surg Br. 2008;90(1):66-71. doi:10.1302/0301-620X.90B1.19767

13. Kawamura K, Chung KC. Treatment of scaphoid fractures and nonunions. J Hand Surg Am. 2008;33(6):988-97. doi:10.1016/j.jhsa.2008.04.026

14. Large TM, Adams MR, Loeffler BJ, Gardner MJ. Posttraumatic Avascular Necrosis After Proximal Femur, Proximal Humerus, Talar Neck, and Scaphoid Fractures. J Am Acad Orthop Surg. 2019;27(21):794-805. doi:10.5435/JAAOS-D-18-00225

15. Cadoux-Hudson D, Muir D, Brewster M. Are outcomes of proximal row carpectomy and four-corner fusion dependent on the diagnosis of scapholunate advanced collapse or scaphoid non-union advanced collapse? a systematic review. Musculoskelet Surg. 2025. doi:10.1007/s12306-025-00939-0

16. Gelberman RH, Gross MS. The vascularity of the wrist. Identification of arterial patterns at risk. Clin Orthop Relat Res. 1986;(202):40-9.

17. Bergman S, Petit A, Rabarin F, et al. Preiser's disease or avascular osteonecrosis of the scaphoid: An updated literature review. Hand Surg Rehabil. 2021;40(4):359-368. doi:10.1016/j.hansur.2021.03.005

18. Herbert TJ, Fisher WE. Management of the fractured scaphoid using a new bone screw. J Bone Joint Surg Br. 1984;66(1):114-23. doi:10.1302/0301-620X.66B1.6693468

19. Jiranek WA, Ruby LK, Millender LH, Bankoff MS, Newberg AH. Long-term results after Russe bone-grafting: the effect of malunion of the scaphoid. J Bone Joint Surg Am. 1992;74(9):1217-28.

20. Parvizi J, Wayman J, Kelly P, Moran CG. Combining the clinical signs improves diagnosis of fractures of the scaphoid. J Bone Joint Surg Br. 1998;80(4):557-60. doi:10.1302/0301-620x.80b4.8418

21. Kwee RM, Kwee TC. Ultrasound for diagnosing radiographically occult scaphoid fracture. Skeletal Radiol. 2018;47(9):1205-1212. doi:10.1007/s00256-018-2931-7

22. Tada K, Ikeda K, Okamoto S, et al. Scaphoid Fracture--Overview and Conservative Treatment. Hand Surg. 2015;20(2):204-9. doi:10.1142/S0218810415400018

23. Merrell GA, Wolfe SW, Slade JF. Treatment of scaphoid nonunions: quantitative meta-analysis of the literature. J Hand Surg Am. 2002;27(4):685-91. doi:10.1053/jhsu.2002.34004

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14. Summary: Key Take-Home Points

Epidemiology:

• Most common carpal fracture (60-70%)
• Young males (20-30 years), FOOSH mechanism
• Waist fractures 70%, proximal pole 20%, distal 10%

Anatomy:

• Retrograde blood supply via dorsal carpal branch of radial artery (enters at waist, supplies proximal 70-80%)
• 80% articular cartilage surface → limited vascular entry
• Waist fracture isolates proximal pole → AVN risk

Diagnosis:

• Clinical: Snuffbox tenderness (sensitive) + tubercle tenderness (specific) + axial compression
• 20-25% radiographically occult → MRI gold standard (95-100% sensitivity)
• CT for union assessment at 12 weeks

Classification:

• Herbert: Type A (stable) vs. Type B (unstable—displaced, proximal pole, perilunate)
• Displacement > 1mm → non-union risk 55%

Management:

• SWIFFT trial: Undisplaced waist fractures → cast immobilization (equivalent outcomes to surgery, fewer complications)
• Below-elbow cast, 8-12 weeks, CT confirmation of union
• Surgery for: Displaced > 1mm, proximal pole, perilunate, humpback deformity, non-union

Complications:

• Non-union 5-10% (waist), 30% (proximal pole) → requires ORIF + bone graft
• AVN 10-15% (waist), 30-40% (proximal pole) → vascularized bone graft
• SNAC wrist: 95% of untreated non-unions → progressive arthritis → salvage (PRC or 4-corner fusion)

Prognosis:

• Undisplaced waist fractures: 90-95% union with conservative treatment
• Functional outcomes excellent if union achieved
• Early diagnosis and treatment critical—delayed treatment > 4 weeks increases non-union risk

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