Introduction
Anatomy
See Scaphoid
Recall basics of scaphoid kinematics, which are disrupted in scaphoid fractures as follows:
- After a fracture the proximal pole rotates into extension via triquetral-hamate articulation
- After a fracture the distal pole pulled into flexion by scaphotrapeziotrapezoid articulation
- Reverse manipulations create angulation, which has a deleterious effect carpal kinematics and fracture healing
Classification
Scaphoid fractures can be classified by pattern/Russe
- Horizontal oblique
- Transverse
- Vertical oblique
Or by location:
- Distal articular: 2%
- Distal pole: 8%
- Tubercle: 8%
- Waist 65%
- Proximal pole: 15%
Presentation
The mechanism of injury is often a fall on the outstretched hand (FOOSH). This causes dorsiflexion and ulnar deviation of the wrist and intercarpal supination
Diagnosis
Physical examination of a patient with a scaphoid fracture will show typically swelling, a radially deviated posture and so called "anatomic snuff box" tenderness. Tests to perform include:
Radiographs
- PA and lateral views of the hand/wrist
- Oblique views: 45 degrees supination and pronation
- Clinched fist view
- Scaphoid view: ulnar deviation/wrist extension
Plain radiographs may be falsely negative in 35-75% of cases
If fracture of the scaphoid is suspected and the films are negative, immobilize the wrist in a cast or splint for 2 weeks and obtain follow-up radiographs. The surgeon may consider additional imaging:
Triple Phase Bone Scan
- Should be positive within 24 hours and always positive within 48 hours
- Dynamic flow images are most reliable in acute fractures of the scaphoid
- Useful in shortening the duration of immobilization without fracture, decreasing complication rate in fracture unrecognized by plain films
- Problems
- Time for study to complete
- Images not as reliable as CT and MRI (false positive rate 25%)
CT Scan
- Must be obtained in the scaphoid's plane and with thin cuts
- Best for surgical planning and accurate assessment of fracture, displacement, angulation
- Greater sensitivity and specificity than bone scan
- Less sensitivity but greater specificity than MRI (MRI edema may be over-read as trabecular microfracture)
MRI
- Sensitivity: 100%; allows early exclusion of occult fracture
- Accurately detects presence of other occult fractures about the wrist
- Deemed "the gold standard investigation"
- May be over-read
Treatment
Non-operative Management
- Indications: Stable fractures with displacement < 1mm and normal angulation
- Cast must always include the thumb (thumb motion is transmitted through the scaphoid via ligamentous attachments leading to shear across the fracture site)
- Length of cast (short arm vs long arm) and length of immobilization (8 weeks vs 12 weeks) debatable
- Exception: Proximal fractures require ~18 weeks of immobilization
Non-operative Healing Rates
- Tuberosity and distal third: ~ 100%
- Waist: 80-90%
- Proximal: 60-70%
Surgical Management
Indications
- Displaced fractures: >1mm
- Instability
- Fracture angulation (scapholunate angulation <60 degrees)
- Proximal pole fractures
- Nonunions: No healing after 20 weeks closed treatment
- Unrecognized/untreated fracture: 4 weeks
Surgical Options
- Closed reduction with percutaneous pinning
- Closed reduction with percutaneous compression screw
- Open reduction with compression screw
Open Approaches
- Dorsal approach: Proximal pole and waist
- Volar approach: Distal pole
Surgical Technique Pearls
- 1.0 mm guide-wire through center of scaphoid
- Guide-wire inserted volar; direct proximally, dorsally and ulnar
- May place anti-rotation wire parallel to guide-wire
- Drive to level of subchondral bone in proximal pole
- Err toward shorter screw size
- After measurement, drive wire into distal radius to prevent displacement
- Importance of central third placement of screw: 43% greater stiffness; 39% greater load at failure
- ORIF techniques
- Avoid violating the RSCL; preservation maintains the proximal pole within the fossa of distal radius
- If fracture does not reduce with extension and ulnar deviation extend incision to level of RSCL; landmark for realignment is scaphoid articular border with capitate
- Pack corticocancellous bone graft into areas of comminution
Complications
