Wrist Joint

WRIST JOINT

Mdu

RADIOGRAPHIC ANATOMY

WRIST

Basic Projection

POSTERO-ANTERIOR

LATERAL

POSTERO-ANTERIOR

• Position of Patient and Image Receptor

The patient is seated alongside the table, with the affected side nearest to the table.

The elbow joint is flexed to 90 degrees and the arm is abducted, such that the anterior aspect of the forearm and the palm of the hand rests on the image receptor.

If the mobility of the patient permits, the shoulder joint should be at the same height as the forearm.

The wrist joint is placed central to the image receptor and adjusted to include the lower part of the radius and ulna and the proximal two-thirds of the metacarpals.

The fingers are flexed slightly to bring the anterior aspect of the wrist into contact with the image receptor.

The wrist joint is adjusted to ensure that the radial and ulnar styloid processes are equidistant from the image receptor.

The forearm is immobilized using a sandbag.

Direction and Centering of X-ray Beam

The vertical central ray is centred to a point midway between the radial and ulnar styloid processes.

Essential Image Characteristics

The image should demonstrate the proximal two-thirds of the metacarpals, the carpal bones, and the distal third of the radius and ulna.

There should be no rotation of the wrist joint.

Notes;

When the image is undertaken for a scaphoid view the wrist should be in ulnar deviation.

LATERAL

• Position of Patient and Image Receptor

The patient is seated alongside the table, with the affected side nearest to the table.

The elbow joint is extended to bring the medial aspect of the forearm, wrist and hand into contact with the table.

The wrist joint is positioned to include the lower part of the radius and ulna and the proximal two-thirds of the metacarpals on the image receptor.

The hand is rotated externally slightly further to ensure that the radial and styloid processes are superimposed.

The forearm is immobilized using a sandbag.

Direction and Centering of X-ray Beam

The vertical central ray is centered over the styloid process of the radius

Note

If the elbow is extended rather than at right-angles it is often easier to rotate the wrist into a lateral position.

CAPAL BONES

Scaphoid

• Imaging of the carpal bones is most commonly undertaken to demonstrate the scaphoid.
• For suspected scaphoid fractures, three or more projections may be taken

The projections may also be used to demonstrate other carpal bones;

For scaphoid fractures, three or more projections may be taken:

A carpal fracture is a break of one of the eight small bones of the carpus.

These bones are the scaphoid, lunate, capitate, triquetrum, hamate, pisiform, trapezium, and trapezoid.

Fractures of the other carpal bones do occur but the scaphoid is accountable for 60–70% of fractures of the carpal bones.

A; SCAPHOID – POSTERO-ANTERIOR

WITH ULNAR DEVIATION

• Position of patient and image receptor
• The patient is seated alongside the table with the affected side nearest the table.
• The arm is extended across the table with the elbow flexed and the forearm pronated.

If possible, the shoulder, elbow and wrist should be at the level of the tabletop.

The wrist is positioned over the centre of the image receptor and the hand is adducted (ulnar deviation).

Ensure that the radial and ulnar styloid processes are equidistant from the image receptor.

The hand and lower forearm are immobilized using sandbags..

Direction and Centering of X-ray Beam

The vertical central ray is centred midwa between the radial and ulnar styloid processes.

Essential Image Characteristics

The image should include the distal end of the radius and ulna and the proximal end of the metacarpals.

The joint space around the scaphoid should be demonstrated clearly.

B;SCAPHOID – ANTERIOR OBLIQUE

WITH ULNAR DEVIATION

Position of Patient and Image Receptor From the postero-anterior position, the hand and wrist are rotated 45 degrees externally and placed central over an image receptor.

• The hand should remain adducted in ulnar deviation.
• The hand is supported in position, with a non-opaque pad placed under the thumb.

The forearm is immobilized using a sandbag.

Direction and Centring of X-ray Beam

The vertical central ray is centred midway between the radial and ulnar styloid processes.

Essential Image Characteristics

The image should include the distal end of the radius and ulna and the proximal end of the metacarpals.

The scaphoid should be seen clearly, with its long axis parallel to the image receptor

RADIOGRAPHIC ANATOMY WITH ULNA DEVIATION

C;SCAPHOID – POSTERIOR OBLIQUE

Position of Patient and Image Receptor From the anterior oblique position, the hand and wrist are rotated externally through 90 degrees, such that the posterior aspect of the hand and wrist are at 45 degrees to the image receptor.

• The wrist is then supported on a 45-degree no- opaque foam pad.

The forearm is immobilized using a sandbag.

Direction and Centering of X-ray Beam

The vertical central ray is centred over the styloid process of the ulna.

Essential Image Characteristics

The image should include the distal end of the radius and ulna and the proximal end of the metacarpals.

• The pisiform should be seen clearly in profile situated anterior to the triquetral.

The long axis of the scaphoid should be seen perpendicular to the image receptor

D.SCAPHOID POSTERO-ANTERIOR –

ULNAR DEVIATION AND 30-DEGREE

CRANIAL ANGLE

The patient and image receptor are positioned as for the posteroanterior scaphoid with ulnar deviation.

The wrist must be positioned to allow the X-ray tube to be angled at 30 degrees along the long axis of the scaphoid.

Direction and Centering of X-ray Beam

The vertical central ray is angled 30 degrees cranially and centred to the scaphoid.

Essential Image Characteristics

This projection elongates the scaphoid and with ulnar deviation demonstrates the space surrounding the scaphoid.

Notes

• As the X-ray beam is directed towards the patient’s trunk radiation

protection of the gonads should be applied.

Radiological Considerations

Fracture of the waist of the scaphoid may not be clearly visible, if at all, at presentation. It carries a high risk of delayed avascular necrosis of the distal pole, which can cause severe disability.

If suspected clinically, the patient may be re-examined after 10 days of immobilization, otherwise a technetium bone scan or magnetic resonance imaging (MRI) may offer immediate diagnosis.

E. Scaphoid – Lateral

Position of patient and image receptor From the posterior oblique position, the hand and wrist are rotated internally through 45°, such that the medial aspect of the wrist is in contact with the image detector.

The hand is adjusted to ensure that the radial and ulnar styloid processes are superimposed.

The hand and wrist may be immobilised using non-opaque pads and sandbags.

Direction and location of the X-ray beam

The collimated vertical beam is centred over the radial styloid process.

Essential image characteristics

The image should include the distal end of the radius and ulna and the proximal end of the metacarpals.

The image should demonstrate clearly any subluxation or dislocation of the carpal bones.

Carpal tunnel

The carpal bones form a shallow concavity, which, with the bridging flexor retinaculum, forms the carpal tunnel.

The flexor retinaculum is attached to the two medial prominences (the pisiform and the hook of the hamate) and to the two lateral prominences (the tubercle of the scaphoid and the tubercle of the trapezium).

The median nerve along with the flexor tendons pass through the tunnel and any swelling here can cause compression of the median nerve, giving rise to the carpal tunnel syndrome.

Radiographic examination of the bony part of the tunnel is by an axial projection to demonstrate the medial and lateral prominences and the concavity.

Axial – method 1

• Position of patient and image receptor
• The patient is standing facing away from the table.

The detector is placed level with the edge of the tabletop.

The palm of the hand is pressed onto the detector, with the wrist joint dorsiflexed to approximately 135°.

The fingers are curled around under the table to assist in immobilization.

Direction and location of X-ray beam

The collimated vertical beam is centred between the pisiform and the hook of the hamate medially and the tubercle of the scaphoid and the ridge of the trapezium laterally

Axial – method 2 (Fig. 2.17b)

• Position of patient and image receptor
• The patient is seated alongside the table.

The detector is placed on top of a plastic block approximately 8 cm high.

The lower end of the forearm rests against the edge of the block, with the wrist adducted and dorsiflexed to 135°.

This position is assisted using a traction bandage held by the patient’s other hand.

Direction and location of X-ray beam

The collimated vertical central ray is centred between the pisiform and the hook of the hamate medially and the tubercle of the scaphoid and the ridge of the trapezium laterally.

Essential image characteristics

The image should demonstrate clearly the pisiform and the hook of the hamate medially and the tubercle of the scaphoid and the tubercle of the trapezium laterally.