Procedures · Upper Extremity

Wrist Positioning Series

Explore the wrist's anatomy, then use Practice mode to position the PA, oblique, and lateral projections yourself.

wrist

Right

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The routine wrist series

The projections this region is examined with. Set them up yourself in Practice positioning.

PA wrist

Posteroanterior projection · hand pronated

Demonstrates: The carpals, the distal radius and ulna and their joints, and the proximal and mid metacarpals, along with the soft-tissue fat pads and stripes around the wrist. Not every intercarpal space opens on this projection — the carpals are irregular blocks that overlap each other whatever the angle, which is why the wrist has an oblique and a lateral at all.
Part position: Seated at the end of the table with the hand and forearm extended, and the shoulder dropped so that the shoulder, elbow and wrist all sit on the same horizontal plane. The long axis of the hand and wrist is aligned and centred to the receptor, and with the hand pronated the hand is arched slightly so the wrist and carpal area come into close contact with the receptor.
Central ray: 90° to the image receptor, centered to the midcarpal area.
Why it is positioned this way: Dropping the shoulder to the level of the wrist is the step most often skipped, and it is what keeps the forearm from being angled to the receptor — an angled forearm foreshortens the distal radius and ulna and closes the radiocarpal joint. Arching the hand slightly does the same job for the carpals: the carpus is not flat, so a hand left flat leaves the proximal row standing off the receptor. Correctly done, the distal radius and ulna are separated except for possible minimal superimposition where they meet at the distal radioulnar joint, and the concavities on either side of the proximal metacarpal shafts match.

Also covered by this projection

AP wristThe hand supinated instead of pronated, again with the hand slightly arched. It demonstrates the intercarpal spaces and the wrist joint better than the PA, because it puts those spaces more nearly parallel to the diverging rays, and it is a good choice for the carpals when the patient can take the position comfortably.

PA oblique wrist (45° lateral rotation)

PA oblique projection · lateral rotation 45°

Demonstrates: The carpals on the radial side thrown clear of the rest — the trapezium and the scaphoid are well seen here, with only slight overlap from the other carpals along their inner edges. The distal radius and ulna and the metacarpals to at least mid-shaft stay in the picture.
Part position: Seated at the end of the table as for the PA, with the shoulder dropped so the shoulder, elbow and wrist are on the same horizontal plane. The hand and wrist are centred to the receptor, then rotated from the pronated position laterally 45 degrees, with a 45 degree support placed under the thumb side to hold that angle.
Central ray: 90° to the image receptor, centered to the midcarpal area.
Why it is positioned this way: Rotating off the frontal is what separates carpals that overlap each other on the PA, and turning the thumb side up is what brings the radial carpals — the trapezium and scaphoid — to the front of that stack rather than burying them. The support block is what makes the number real: 45 degrees is only 45 degrees if the wrist is held there, and a wrist allowed to sag back toward the receptor gives a shallower oblique that reproduces the PA it was ordered to supplement. Rotated correctly, the ulnar head is partly covered by the distal radius and the bases of the third through fifth metacarpals line up.

Also covered by this projection

Oblique without a support blockThe same 45 degree rotation with the fingers partly flexed so the hand arches and the fingertips rest lightly on the receptor, holding the angle without a block. It is the alternative when no support is available.

Lateromedial wrist

Lateromedial projection · thumb side up

Demonstrates: The wrist in true lateral, with the ulnar head superimposed over the distal radius and the second through fifth metacarpals lined up behind one another. It is the projection that shows front-to-back displacement of a distal radius fracture — the Colles, Smith and Barton patterns are told apart by which way the fragment has gone, and only a lateral answers that.
Part position: Seated at the end of the table with the arm and forearm resting on the table, the wrist and hand placed on the receptor thumb side up, and the shoulder, elbow and wrist on the same horizontal plane. The hand and wrist are aligned and centred to the long axis of the receptor and adjusted into a true lateral with the fingers comfortably extended, supported by a radiolucent block against the extended hand if needed to prevent motion.
Central ray: 90° to the image receptor, centered to the midcarpal area.
Why it is positioned this way: Everything this projection is for depends on the forearm being in true lateral, and the check for that is built into the anatomy: the ulnar head has to sit directly over the distal radius. Any rotation pulls the two apart and the fracture fragment that the lateral was ordered to localise starts to be projected somewhere it is not. Keeping the shoulder, elbow and wrist on one plane is what stops the forearm rotating out of lateral partway along its length, and the support block is there because this is an injured wrist being asked to hold still.

Also covered by this projection

Scaphoid projection with ulnar deviationA special projection, not part of the routine. From the PA position the hand is gently moved toward the ulnar side, which opens up the carpals on the opposite — radial — side of the wrist: the scaphoid, trapezium and trapezoid. It exists because the scaphoid is the most frequently fractured carpal. It is not attempted on a possible wrist trauma until the routine series has been taken and read.

Radial deviationThe mirror of the above and less often taken. From the PA position the hand is moved toward the thumb side, opening the carpals on the opposite — ulnar — side: the hamate, pisiform, triquetrum and lunate.

Procedures lessonHand & wrist