Ortho Hors D'oeuvres (Answer):
To review, this is a 23 year-old male presenting with left wrist pain after fall onto outstretched hands.
Questions and Answers:
1) What are the findings on the initial radiographs?
In diagnosis of wrist pathology, adequate radiographs are necessary. In order to evaluate for radiograph adequacy, the following criteria must be met: On anterior radiographs, the three lines across the top and bottom of the carpal bones (lines of gilula) must be paralell and separated by 1-2 mm (1). Overlap indicates wrist rotation and poor bony visualization. The scaphoid should appear long (2). There should be no overlap between the radius and ulna (3), and the middle of the lunate should sit just distal to the most ulnar aspect of the distal radius (4).
On lateral radiographs, the radius-lunate-capitate complex should appear linear and straight (1). There should be perfect overlap between the radius and ulna (2).
Once adequacy of radiographs has been established, a careful evaluation for cortical irregularities yields the following injury to the scaphoid waist, most apparent on lateral films:
The injury is also visible on AP films and scaphoid-dedicated films with ulnar deviation as seen below:
Radiographs are only 50% sensitive for displacement, so it is impossible to comment on the operative or nonoperative nature of the fracture.
2) What further steps should be taken in examination or imaging for appropriate diagnosis?
Any patient with a mechanism consistent with a fall onto outstretched hand (FOOSH) should be thoroughly evaluate for scaphoid tenderness and possible scaphoid fracture, especially given the poor sensitivity of radiographs. Pain at the anatomic snuffbox is 96% sensitive and 39% specific for scaphoid fracture. Pain with scaphoid compression, in which the thumb is compressed axially along the first metacarpal, is 82-87% sensitive and 58% specific for a scaphoid fracture, and can identify fracture even when a splint has already been placed.
After a scaphoid fracture is suspected by physical examination, careful attention should be paid to radiographs to rule out associated scapholunate dissociation. The scapholunate angle in normal lateral radiographs is less than 60. Any angle larger than that is suspicious for dissociation. Additionally, any space between lunate and scaphoid greater than 3mm on AP films is concerning for scapholunate dissociation.
Even in the setting of perfectly normal radiographs, an occult scaphoid fracture is a possibility. Scaphoid fractures can be missed approximately 27% of the time when using only x-rays for diagnosis.
Current practice recommends the following management of radiographically-negative suspected scaphoid fracture: the placement of a short arm (distal to elbow) thumb spica splint that allows for motion of the interphalangeal joint of the thumb and follow-up with a primary care physician or urgent care within 7-14 days for repeat examination and radiographs, as by this time in bone remodeling osteoclasts have made the fracture lines more apparent. However, there are some recent studies that argue that the economic cost of immobilization and follow-up far outweigh the cost of further imaging in the emergency department.
If a barrier to follow-up is perceived or costs of empiric immobilization seem to outweigh long emergency department evaluation, CT or MRI have been demonstrated to have reasonable sensitivity for scaphoid fractures (83% and 96% respectively). Ultrasound has recently been demonstrated to have a sensitivity of 77.8-100% in a small study.
3) What is the appropriate emergency department management?
For this patient, with the radiographically obvious scaphoid fracture, no further imaging tests are necessary in the emergent setting. Radiographically apparent scaphoid fractures should be placed in a short arm thumb spica cast (similarly to occult suspected scaphoid fractures) and should follow-up with an orthopedic or hand specialist within 3-5 days, as they will likely need operative fixation.
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