Wrist & distal forearm

Published on 01/04/2015 by admin

Filed under Radiology

Last modified 01/04/2015

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Wrist & distal forearm

The standard radiographs

PA, Lateral, Scaphoid series.

Abbreviations

AVN, avascular necrosis; C, capitate; L, lunate; PA, posterior-anterior (view); R, radius.

Normal anatomy

PA projection: bones and joints

The articular surface of the radius lies distal to that of the ulna in 90% of normal people.

The carpal bones are arranged in two rows, bound together by strong ligaments:

image

Lateral projection: bones and joints

The dorsal cortex of the distal radius is completely smooth—no crinkles, no irregularity. This cortex should be as smooth as a baby’s bottom.

The alignment of the carpal bones may appear confusing but identifying the important anatomy is actually very simple. Don’t worry about the overlapping bones. Just think: apple, cup, saucer.

Analysis: the checklists

The PA view will appear fairly comforting to an inexperienced observer because all of the carpal bones are clearly shown. The lateral radiograph may appear terrifyingly complex and difficult to analyse because of the numerous overlapping bones. There is a very clear message: do not be afraid!

The lateral view is diagnostically very, very, important, so we will show you how to quickly and confidently analyse every lateral radiograph using a simple checklist.

The scaphoid series

Many undisplaced scaphoid fractures are not visualised on the two standard (wrist) views. Two extra views produces a better return. Therefore, a four view scaphoid series is essential and should be requested whenever there is ‘snuffbox’ tenderness:

The two additional images will vary between Emergency Departments. Importantly, two of the four projections will always include a true PA and a true lateral of the wrist.

Scaphoid fractures are mainly hairline fractures and lucent; they are not sclerotic. Occasionally the fracture is displaced.

Analysis: ask yourself three questions.

Wrist myths

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