(See also Overview of Fractures Overview of Fractures A fracture is a break in a bone. Most fractures result from a single, significant force applied to normal bone. In addition to fractures, musculoskeletal injuries include Joint dislocations... read more 
.)
The scaphoid is the most commonly injured carpal bone. Scaphoid fractures usually result from wrist hyperextension, typically during a fall on an outstretched hand. They can disrupt the blood supply to the proximal scaphoid. Osteonecrosis Osteonecrosis (ON) Osteonecrosis is a focal infarct of bone that may be caused by specific etiologic factors or may be idiopathic. It can cause pain, limitation of motion, joint collapse, and secondary osteoarthritis... read more is thus a common complication, even when initial care is optimal, and can cause disabling, degenerative arthritis of the wrist.
Symptoms and Signs of Scaphoid Fractures
The radial side of the wrist is swollen and tender. If patients have these symptoms, scaphoid fracture should be considered. More specific signs include
Pain during axial compression of the thumb
Pain during wrist supination against resistance
Particularly tenderness in the anatomic snuffbox during ulnar wrist deviation
The anatomic snuffbox is palpated just distal to the radius between the extensor pollicis longus, extensor pollicis brevis, and abductor pollicis longus tendons.
Diagnosis of Scaphoid Fractures
Plain x-rays
MRI
If a scaphoid fracture is suspected and imaging is nondiagnostic, presumptive treatment with a thumb spica splint and follow-up x-ray
Initially, plain x-rays (anteroposterior, lateral, and oblique views) are taken but are often normal. In a recent meta-analysis, false-negative rates in most series ranged from 6 to 18% for plain x-rays (1 Diagnosis reference Scaphoid fractures usually result from wrist hyperextension. They may not be visible on initial x-rays. Complications can be severe. (See also Overview of Fractures.) The scaphoid is the most... read more 
).
If x-rays are normal but a fracture is still suspected, MRI can be done. MRI is being increasingly used to diagnose scaphoid fractures because it is more accurate than CT or bone scanning in the acute setting (1 Diagnosis reference Scaphoid fractures usually result from wrist hyperextension. They may not be visible on initial x-rays. Complications can be severe. (See also Overview of Fractures.) The scaphoid is the most... read more ).
If a fracture is suspected clinically and imaging is nondiagnostic, it is treated presumptively as a fracture and a thumb spica splint Thumb spica splint 
is applied. The patient should be re-examined 1 week after injury. If the patient is still in pain or if the wrist is tender when examined 1 week after injury, repeat plain x-rays are taken.
Thumb spica splint
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Diagnosis reference
1. Carpenter CR, Pines JM, Schuur JD, et al: Adult scaphoid fracture. Acad Emerg Med 21 (2):101–121, 2014. doi: 10.1111/acem.12317
Treatment of Scaphoid Fractures
Thumb spica immobilization
Many nondisplaced fractures can be treated definitively with a thumb spica cast, which is worn for up to 6 to 8 weeks. A thumb spica splint can be applied if cast application needs to be deferred.
Sometimes open reduction with internal fixation (ORIF) is required.
Key Points
Scaphoid fractures usually result from wrist hyperextension, typically during a fall on an outstretched hand.
These fractures can disrupt the blood supply to the proximal scaphoid; thus, osteonecrosis is a common, sometimes disabling, complication.
Take anteroposterior, lateral, and oblique x-rays; if imaging is normal or nondiagnostic but clinical findings suggest a scaphoid fracture, do MRI or immobilize with thumb spica splint and arrange for repeat x-rays in 1 week.
