Clinically Relevant Anatomy
The scaphoid is the most commonly fractured of the 8 carpal bones of the wrist. It is made up of a proximal and distal pole which are joined by a waist. Scapohid fractures make up 50-80% of all carpal fractures.  Blood supply is provided by a subdivision of the radial artery and travels distal to proximal. The proximal pole has no direct blood supply and is prone to avascular necrosis (AVN).
Mechanism of Injury / Pathological Process
Mechanism of injury is usually a fall onto an outstretched arm with wrist hyperextended and radial deviation. This position causes axial loading through the scaphoid. Less common mechanisms of injury are:
- wrist extension with deceleration such as with the hand on a steering wheel
- 'kickback' injuries from machinery
- hyperflexion injuries
- direct impact to the scaphoid
Most injuries are seen in men aged 15-30. 75-80% of fractures occur through the waist of the bone. 15-20% occur at the proximal pole. 10-15% of fractures occur at the distal pole.
Clinical presentation includes swelling and pain over the anatomical snuff box. The anatomical snuff box is the area between the extensor pollicis longus and the extensor pollicis brevis. Patient will usually also complain of pain with pressure over the scapoid tubercle. 
AP and lateral radiographs along with additional scaphoid views (pronated oblique and ulnar-deviated oblique) are used in diagnosing a scaphoid fracture. Up to 15% of scaphoid fractures are not evident on initial radiograph, however.  If fracture is suspected,MRI is the next line of imaging to confirm the diagnosis. 
Management / Interventions
Cast immobilization is the standard treatment for treating a scaphoid fracture. With cast immobilization, chance of non-union is approximately 20%. Therefore, with displaced or unstable fractures, operative treatment is recommended.  Though this improves the rate of non-union, the complication rate for ORIF is 30%.
Fractures are usually classified by Herbert and Fisher's system:
A: Acute but stable fractures such as fractures of the tubercle, incomplete or undisplaced fractures of the waist
B: Acute unstable fractures such as distal oblique fractures, complete waist fractures, proximal pole fractures, and
C: Fractures with evidence of delayed union
D: Fractures with established non-union
Differential diagnosis includes Colles' fracture, Salter-Harris fracture, other carpal fractures, scapho-lunate complex injury.
A systemic review suggests that percutaneous fixation may result in faster union and return to work or sport. There was no difference noted between cast fixation and ORIF. The authors suggest that cast treatment is a good treatment option for most. Surgery should be reserved for high level athletes and manual workers who cannot work in a cast.
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Recent Related Research (from Pubmed)
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- ↑ Alshryda SJM, Shah AB, Rhodes S, Odak SS, Murali SR, Ilango B. Interventions for treating acute fractures of the carpal scaphoid bone in adults. Cochrane Database of Systematic Reviews 2007, Issue 2. Art. No.: CD006523. DOI:fckLR10.1002/14651858.CD006523.fckLRA B
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Bethel J. Scaphoid Fracture: diagnosis and management. Emergency Nurse. July, 2009. 17(4): 24-29.
- ↑ Henriksen et al. Two-Dimensional Image Fusion of Planar Bone Scintigraphy and Radiographs in Patients with Clinical Scaphoid Fracture: An Imaging Study. Acta Radiologica. February, 2009. 50(1): 71-77.
- ↑ Pfeiffer et al. A prospective multi-center cohort study of acute non-displaced fractures of the scaphoid: operative versus non-operative treatment. BMC Musculoskeletal Disorders. May, 2006. 7:41.
- ↑ 5.0 5.1 Modi et al. Operative versus nonoperative treatment of acute undisplaced and minimally displaced scaphoid waist fractures-A systemic review. Injury, Int. J. Care Injured. 2009. 40: 268-273.
The Movement System
Learn about the movement system with Shirley Sarhmann & Mark Comerford in this month's members learn topic.