Scaphoid Fractures Diagnosis & Management
Scaphoid fractures are the most commonly fractured carpal bone, accounting for 2-3% of all fractures and ~10% of all hand fractures (Duckworth, 2012). They account for approximately 60% of all carpal fractures (Hove, 1999). There is a male predominance with low-energy falls being the most common etiology although men are more likely to sustain their fracture after a high-energy injury. Approximately 65% of injuries occur at the waist, with another 25% occuring in the proximal third.
The major blood supply of scaphoid is provided by the dorsal carpal branch of the radial artery which provides retrograde flow to the proximal 80% of scaphoid via an intraosseous supply. The superficial palmar arch supplies the distal 20%. This intraosseous retrograde flow makes the scaphoid particular susceptible to avascular necrosis, which can lead to scaphoid nonunion and eventual collapse (termed SNAC: scaphoid nonunion advanced collapse).
History and Physical
Scaphoid fractures tend to occur in young and middle aged men. As patients age, the distal radial metaphysis is much more likely to fail than the scaphoid. The typical mechanism involves falling onto a hyperextended wrist with radial deviation (Ring, 2000). The hand and wrist should be observed for any signs of soft tissue swelling, effusion, ecchymosis or deformities. Strength, range of motion and a thorough neurovascular exam should be performed. Comparison should be made to the unaffected wrist.
The initial imaging modality of choice remain radiographs. Standard wrist xrays include AP, lateral and oblique views. Dedicated scaphoid series can also be obtained if clinical concern is high enough (Cheung, 2006). A PA view in ulnar deviation will give the so-called ‘scaphoid view’. A 45० pronation view can also be obtained. Overall, plain radiographs are about 70% sensitive for scaphoid fractures (Gabler, 2001). If the clinical suspicion is high enough despite normal appearing initial radiographs, a thumb spica splint or cast is usually administered. Repeat radiographs at approximately 2 weeks are usually recommended. Ultrasound has a growing but largely undefined role in the initial evaluation of potential scaphoid fractures. In one chinese study, ultrasound was 80% sensitive and specific compared to 36% and 40% respectively for xrays (Jain, 2018).
Because of the economic implications of immobilization and repeat imaging, some orthopedists have suggested early utilization of advanced imaging (Dorsay, 2001). There is no clear consensus on optimal advanced imaging modality for suspected scaphoid fractures, however MRI is most commonly used. MRI is 90-100% sensitive and specific for scaphoid fractures (Raby, 2001). MRI loses sensitivity on proximal pole injuries, which can be improved with gadolinium-enhanced MRI (Cerazal, 2000).
The Herbert and Fisher classification is commonly used to describe scaphoid fractures. Herbert classification B2 is the most common at 36.4% (Duckworth, 2012).
The majority of scaphoid fractures are nondisplaced or minimally displaced and can be treated with immobilization for 8-12 weeks in a thumb spica cast (Kawamura, 2008). The healing rate of nondisplaced waist scaphoid fractures with cast immobilization is 88% to 95%, provided that treatment is started within 3 weeks after injury (Cooney, 1980). There is no consensus on long arm vs short arm casting. In patients with normal radiographs, but a high degree of clinical suspicion, patients should be placed in a thumb spica splint with repeat radiographs in roughly 2 weeks. Some surgeons recommend early ORIF even for nondisplaced fractures to avoid complications such as more frequent office visits to check whether the cast fits properly, more frequent radiographs to assess fracture alignment, potential skin breakdown, prolonged immobilization until complete healing has occurred, stiffness of immobilized joints, and a longer time to healing.
Scaphoid fractures are the most common carpal bone fracture and they tend to occur in young men. A careful clinical exam, including anatomic snuff box tenderness, axial compression and volar palpation of the scaphoid tubercle are very sensitive in evaluating for a scaphoid fracture. Radiographs are the initial imaging study of choice, however only 70% sensitive. MRI and CT are utilized in the appropriate patient and the role of ultrasound remains unclear.
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