Mastering the Management of Scaphoid Fractures: Understanding Classification, Treatment, and Complications

Scaphoid Fractures

SUMMARY

Scaphoid Fractures are the most common carpal bone fracture, often occurring after a fall onto an outstretched hand. Diagnosis can generally be made by dedicated radiographs but CT or MRI may be needed for confirmation. Treatment may require a prolonged period of cast immobilization, percutaneous surgical fixation, or open reduction and internal fixation.

EPIDEMIOLOGY

ETIOLOGY

Pathophysiology

• most common mechanism of injury is axial load across a hyper-dorsiflexed, pronated and ulnarly-deviated wrist
• common in contact sports
• transverse fracture patterns are considered more stable than vertically or obliquely oriented fractures

Associated conditions

• SNAC (Scaphoid Nonunion Advanced Collapse)

ANATOMY

Osteology

• complex 3-dimensional structure described as resembling a boat, skiff, and twisted peanut
• oriented obliquely from extremity's long-axis (implications for advanced imaging techniques)
• largest bone in proximal carpal row
• > 75% of scaphoid bone is covered by articular cartilage
• articulates with radius, lunate, trapezium, trapezoid, and capitate

Blood supply

• major blood supply is dorsal carpal branch (branch of the radial artery)
• enters scaphoid in a nonarticular ridge on the dorsal surface and supplies proximal 80% of scaphoid via retrograde blood flow
• minor blood supply from superficial palmar arch (branch of volar radial artery)
• enters distal tubercle and supplies distal 20% of scaphoid
• creates vascular watershed and poor fracture healing environment

Biomechanics

link between proximal and distal carpal row; both intrinsic and extrinsic ligaments attach and surround the scaphoid; the scaphoid flexes with wrist flexion and radial deviation and extends during wrist extension and ulnar deviation (same as proximal row)

CLASSIFICATION

Herbert and Fisher Classification (based on fracture stability)

• Type A: Stable, acute fractures
• Type B: Unstable, acute fractures (distal oblique, complete waist, proximal pole, trans-scaphoid and perilunate associated fractures)
• Type C: Delayed union characterized by cyst formation and fracture widening
• Type D: Nonunion

Mayo classification (based on location of fracture line)

• Type I: Distal tubercle fracture
• Type II: Distal articular surface fracture
• Type III: Distal third fracture
• Type IV: Middle third fracture
• Type V: Proximal third fracture

Russe Classification (based on fracture pattern)

• Type I: Horizontal oblique fracture line
• Type II: Transverse fracture line
• Type III: Vertical oblique fracture line

PRESENTATION

History

• high or low energy fall onto outstretched hand

Symptoms

• variable level of pain over wrist

Physical exam

• inspection
• wrist swelling
• rarely any ecchymosis, hematoma, or gross deformity
• motion
• worsened wrist pain with circumduction
• pain with resisted pronation
• provocative tests
• anatomic snuffbox tenderness dorsally
• scaphoid tubercle tenderness volarly
• scaphoid compression test
• positive test when pain reproduced with axial load applied through thumb metacarpal
• 87-100% sensitivity and 74% specificity when all three tests positive within 24 hours of injury

IMAGING

Radiographs

• recommended views
• neutral rotation PA
• lateral
• semi-pronated (45°) oblique
• scaphoid
• 30 degree wrist extension, 20 degree ulnar deviation
• waist fractures seen best
• if radiographs are negative (27%) and there is a high clinical suspicion, repeat radiographs in 14-21 days

Bone scan

• indications: occult fractures in acute setting
• sensitivity and specificity: specificity of 98%, and sensitivity of 100%, PPV 85% to 93% when done at 72 hours

MRI

• indications: most sensitive for diagnosis of occult fractures < 24 hours; immediate identification of fractures / ligamentous injuries; assessment of vascular status of bone (vascularity of proximal pole)
• sensitivity and specificity: approach 100% for occult fractures

CT scan with 1mm cuts along scaphoid axis

• indications: best modality to evaluate fracture location, angulation, displacement, fragment size, extent of collapse, and progression of nonunion or union after surgery
• sensitivity and specificity: 62% sensitivity and 87% specific for determining stability and fracture; less effective than bone scan and MRI to diagnose occult fracture

TREATMENT

Nonoperative

• cast immobilization
• indications: stable nondisplaced fracture (majority of fractures); if patient has normal radiographs but there is a high level of suspicion can immobilize in thumb spica and reevaluate in 12 to 21 days
• outcomes: scaphoid fractures with <1mm displacement have union rate of 90%

Operative

• percutaneous screw fixation
• indications: unstable fractures as shown by proximal pole fractures, displacement > 1 mm without significant angulation or deformity, non-displaced waist fractures (to allow decreased time to union, faster return to work/sport, similar total costs compared to casting)
• outcomes: union rates of 90-95% with operative treatment of scaphoid fractures; CT scan is helpful for evaluation of union
• open reduction internal fixation
• indications: significantly displaced fracture patterns, 15° scaphoid humpback deformity, radiolunate angle > 15° (DISI), intrascaphoid angle of > 35°, scaphoid fractures associated with perilunate dislocation, comminuted fractures, unstable vertical or oblique fractures
• outcomes: accuracy of reduction correlated with rate of union

COMPLICATIONS