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SCAPHOID FRACTURE

Introduction

The scaphoid is one of eight carpal bones, and fractures to this bone result from forced dorsiflexion of the wrist, such as during a fall on an outstretch hand (FOOSH). Scaphoid fractures are significantly more prevalent among younger, male individuals and are typically the result of a fall or sports-related injury. The healing process is primary bone healing, with bridging trabeculae.

Related Anatomy

  • Radius
  • Capitate
  • Lunate
  • Radiolunate ligament
  • Radioscaphocapitate ligament
  • Anatomic snuffbox

Pathophysiology

  • The force/load applied to the hand must be concentrated to the radial half of the palm, with the wrist in 95–100° dorsiflexion. While the proximal half of the scaphoid is stabilized between the radius, capitate and volar capsular ligaments, bending loads applied to the distal half of the scaphoid cause the fracture to occur between the supported and unsupported zones.

Classification and Incidence

  • The scaphoid is divided into three areas: tubercle (distal), waist (middle) and proximal 1/3. Russe classified scaphoid fractures as they relate to the long axis of the bone: horizontal oblique (HO), transverse (T) and vertical oblique (VO).1
  • In one study, incidence by area and classification were:2
    • Tubercle:  10.0%
    • Waist:  70.0%
    • T:  42.0%
    • HO:  24.5%
    • VO:  3.5%
    • Proximal 1/3:  20.0%
  • ~13% of patients with scaphoid fractures had other associated injuries, including distal radius fracture and radial styloid fracture.2
  • In the US, the overall incidence rate between 2002 and 2006 was 1.47 per 100,000 person-years (PYs); rates were 0.97 and 1.98 per 100,000 PYs among women and men, respectively.3 Incidence rate was highest among persons aged 10–19 years (3.38 per 100,000 PYs).3
  • Herbert developed another classification system that combined fracture anatomy, stability and history to produce an alphanumeric grade with prognostic significance:4

Type A: Stable Acute Fractures

A1: Fracture of Tubercle

A2: Incomplete Fracture Through Waist

Type B: Unstable Acute Fractures

B1: Distal Oblique Fracture

B2: Complete Fracture of Waist

B3: Proximal Pole Fracture

B4: Trans-Scaphoid-Perilunate Fracture Dislocation of Carpus

Type C: Delayed Union

Type D: Established Nonunion

D1: Fibrous Union

D2: Pseudarthrosis

Differential Diagnosis

  • Distal radius fracture
  • Trans-scaphoid perilunate dislocation
  • Scaphoid impaction syndrom
  • Scapholunate dissociation
  • Wrist dislocation
Clinical Presentation Photos and Related Diagrams
  • Scaphoid Fracture with arrow on fracture line (Hover over right edge to see more images)
    Scaphoid Fracture with arrow on fracture line (Hover over right edge to see more images)
  • Scaphoid (Navicular) Fracture Prox1/3;Mid1/3 scaphoid [ulnar deviated] view with slight increase density suggest possible AVN
    Scaphoid (Navicular) Fracture Prox1/3;Mid1/3 scaphoid [ulnar deviated] view with increase density suggest possible AVN
  • Scaphoid (Navicular) Fracture radial deviate view with fracture line not visible
    Scaphoid (Navicular) Fracture radial deviate view with fracture line not visible
  • Scaphoid (Navicular) Fracture MRI T1 showing fracture and no AVN
    Scaphoid (Navicular) Fracture MRI T1 showing fracture and no AVN
  • Scaphoid (Navicular) Fracture MRI T2 showing marrow edema and fracture with no sign of AVN
    Scaphoid (Navicular) Fracture MRI T2 showing marrow edema and fracture with no sign of AVN
  • Scaphoid (Navicular) Fracture CT showing no healing of fracture
    Scaphoid (Navicular) Fracture CT showing no healing of fracture
  • Scaphoid (Navicular) Fracture castedwithout healing
    Scaphoid (Navicular) Fracture casted without healing
  • Scaphoid (Navicular) Fracture (arrow) undergoing internal fixation with screw
    Scaphoid (Navicular) Fracture (arrow) undergoing internal fixation with screw
  • Scaphoid (Navicular) Fracture internally fixated with screw
    Scaphoid (Navicular) Fracture internally fixated with screw
Symptoms
Wrist pain following an injury
Swelling and/or bruising on thumb side of wrist
Difficulty gripping and grasping secondary to wrist pain
Pain with twisting thumb or wrist
History of wrist contusion sprain or injury
Typical History

A 28-year-old male was racing his dirt bike when he hit a rock and flew off the bike, landing on his outstretched left hand.  He presents with swelling and pain in the wrist.  Initial x-ray was negative but he has marked tenderness in the anatomic snuffbox area at the base of the thumb.  Subsequent MRI showed a non-displaced scaphoid fracture.

Positive Tests, Exams or Signs
Scaphoid Tenderness
Capillary Refill
Fracture Crepitus, Deformity, Motion and Tenderness
Passive Stretch Test
Radial Pulse
Range of Motion: Active
Range of Motion: Passive
Sensory Exam by Nerve
Work-up Options
Magnetic resonance imaging - MRI with contrast
Radiology studies - Computerized tomography (CT) scanning
Radiology studies - X-ray
Images (X-Ray, MRI, etc.)
  • Non-displaced scaphoid fracture mid 1/3 proximal 1/3 junction (Hover over right edge to see more images)
    Non-displaced scaphoid fracture mid 1/3 proximal 1/3 junction (Hover over right edge to see more images)
  • Non-displaced scaphoid fracture but not visible on this oblique view
    Non-displaced scaphoid fracture but not visible on this oblique view
  • Non-displaced scaphoid fracture on CT with no bridging callus
    Non-displaced scaphoid fracture on CT with no bridging callus
  • Non-displaced scaphoid fracture on MRI with no signs of AVN
    Non-displaced scaphoid fracture on MRI with no signs of AVN
  • Non-displaced scaphoid fracture on MRI with no signs of AVN
    Non-displaced scaphoid fracture on MRI with no signs of AVN
Treatment Options
Conservative: 
  • Conservative: Non-displaced fractures should be treated with casting. Most surgeons include the thumb in the spica cast but others leave the thumb free for greater hand function.5 Immobilization for 6–8 weeks is generally sufficient to allow for union, but this will vary depending upon the patient’s age and mechanism of injury. Displaced or oblique fractures are typically placed in a long-arm cast, with the elbow at 90°, although there is no consensus on elbow immobilization.
Operative: 
  • Operative: displaced waist and proximal pole fractures require internal fixation owing to their high risk of nonunion and avascular necrosis; displacement of >1 mm is defined as an unstable fracture; optimal screw placement is along the central axis with a long screw into subchondral bone.6,7
Complications
  • Nonunion, avascular necrosis, scapholunate advanced collapse (SLAC) or scaphoid nonunion advanced collapse (SNAC) wrist, degenerative disease of the scaphotrapezotrapezoidal (STT) joint.
Outcomes
  • Healing rates of non-displaced waist fractures are between 88–95%, if immobilization occurs within 3 weeks of injury. Controlled studies of operative treatment versus cast immobilization for acute non-displaced or minimally displaced fractures failed to show a clear benefit of early fixation. Long-term outcomes do not differ between cast immobilization and internal fixation. However, internal fixation is better from an economic and social perspective due to earlier return to work. 
Key Educational Points
  • The scaphoid is the most commonly fractured bone in the carpus.
  • It is vulnerable to injury because it functions as a link between the prximal and sital carpal rows.
  • Approximately 80% of scaphoid fractures occur at the waist.
  • The major blood supply to the scaphoid is a branch of the radial artery that enters the dorsal ridge distally.
  • The wrist and thumb should be immobilized if a fracture is suspected given snuffbox tenderness despite negative radiographs at time of trauma. Images should be repeated in 2-3 weeks.
  • Fracture nonunion and avascular necrosis is more common in proximal pole fractures, given the retrograde blood supply to the proximal aspect of the scaphoid.
Practice and CME
References

Cited

  1. Russe, O. Fracture of the carpal navicular. Diagnosis, non-operative treatment, and operative treatment. J Bone Joint Surg Am 1960;42:759-68. PMID: 13854612
  2. Leslie IJ, Dickson RA. The fractured carpal scaphoid. Natural history and factors influencing outcome. J Bone Joint Surg Br 1981;63(2):225-30. PMID: 7217146
  3. 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. PMID: 20684922
  4. Herbert TJ. The Fractured Scaphoid. Quality Medical Publishing: St. Louis, 1990.
  5. Doornberg JN, et al. Nonoperative treatment for acute scaphoid fractures: a systematic review and meta-analysis of randomized controlled trials. J Trauma 2011;71(4):1073-1081. PMID: 21986747
  6. McCallister WV, et al. Central placement of the screw in simulated fractures of the scaphoid waist: a biomechanical study. J Bone Joint Surg Am 2003;85(1):72-7. PMID: 12533575
  7. Dodds SD, Panjabi MM, Slade JF 3rd. Screw fixation of scaphoid fractures: a biomechanical assessment of screw length and screw augmentation. J Hand Surg Am 2006;31(3):405-13. PMID: 16516734