Hand and Wrist X-rays

Accurate imaging of the hand and wrist plays a vital role in diagnosing fractures, dislocations, and joint pathologies. As radiographers, precision and attention to detail are essential to ensure high-quality diagnostic images. Let’s dive into the key aspects of anatomy and positioning for hand and wrist x-rays, step by step.

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Anatomy Spotlight: What’s in the Frame?

The hand and wrist are complex yet elegant structures, comprising:

• Hand: 27 bones, including the phalanges (14), metacarpals (5), and associated joints.
• Wrist (carpus): 8 carpal bones arranged in two rows:
  • Proximal row: Scaphoid, lunate, triquetrum, pisiform.
  • Distal row: Trapezium, trapezoid, capitate, hamate.

An accurate x-ray of the hand and wrist must clearly delineate these bones, their articulations, and any soft tissue involvement. Do you know your carpal mnemonic? (“Some Lovers Try Positions That They Can’t Handle”) It’s an efficient way to recall the arrangement of the carpal bones, starting from the radial (thumb) side of the wrist.

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Positioning: Setting the Stage for Success

Proper positioning is the foundation of a diagnostic image. Each view serves a unique purpose, ensuring we capture the right anatomy and potential pathologies.

1. PA Hand X-ray

• Purpose: Visualize the entire hand, including phalanges, metacarpals, and the carpal bones. Ideal for assessing fractures, joint alignment, and degenerative changes.
• Positioning Steps:
  1. Seat the patient beside the x-ray table.
  2. Place the palmar surface of the hand flat on the image receptor (IR), fingers spread slightly to avoid overlap.
  3. Align the central ray (CR) perpendicular to the third metacarpophalangeal (MCP) joint.
  • Tip: Ensure the fingers are extended, as flexion may obscure joint spaces.

2. PA Oblique Hand X-ray

• Purpose: Assess metacarpal fractures and joint spaces with reduced superimposition of structures.
• Positioning Steps:
  1. Rotate the hand externally (laterally) 45° from the PA position.
  2. Use a radiolucent wedge to maintain the oblique angle if necessary.
  3. Direct the CR perpendicular to the third MCP joint.
  • Pro Tip: Check for equal spacing between the metacarpal heads and avoid overlapping of digits.

3. Lateral Hand X-ray

• Purpose: Evaluate displacement of fractures and foreign bodies.
• Positioning Steps:
  1. Position the hand in a “karate chop” pose (ulnar aspect against the IR).
  2. Fan the fingers to separate the phalanges for a lateral projection of each digit.
  3. Align the CR perpendicular to the second MCP joint.
  • Key Consideration: A true lateral position ensures superimposition of metacarpals and proper visualization of soft tissues.

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Wrist X-rays: A Focus on Stability and Structure

1. PA Wrist X-ray

• Purpose: Assess fractures (e.g., distal radius, scaphoid) and degenerative conditions.
• Positioning Steps:
  1. Rest the forearm and wrist flat on the IR, palm down.
  2. Slightly flex the fingers to bring the wrist closer to the IR.
  3. Direct the CR perpendicular to the midcarpal area.
  • Reminder: Include the distal radius and ulna, as well as the proximal metacarpals.

2. Lateral Wrist X-ray

• Purpose: Evaluate alignment of carpal bones, distal radius, and ulna, particularly in cases of trauma.
• Positioning Steps:
  1. Rest the forearm and ulnar aspect of the wrist on the IR, thumb pointing upward.
  2. Align the CR perpendicular to the wrist joint.
  • Tip: A true lateral shows the pisiform overlapping the scaphoid and the distal radius aligned with the ulna.

3. PA Oblique Wrist X-ray

• Purpose: Highlight fractures in the scaphoid and trapezium, reducing overlap of carpal bones.
• Positioning Steps:
  1. Rotate the wrist externally 45° from the PA position.
  2. Use a sponge for support if needed.
  3. Center the CR perpendicular to the midcarpal region.

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Image Evaluation: What Defines a Perfect X-ray?

For each view, ensure:

• Sharp bony detail: Adequate exposure without motion or artifacts.
• Alignment and symmetry: Equal spacing between joints, no rotation of the wrist or hand.
• Anatomy included: For the hand, ensure all phalanges, metacarpals, and carpals are visible. For the wrist, include distal radius and ulna.

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Final Thoughts

Positioning for hand and wrist x-rays requires precision and practice, but mastering the techniques will set you apart as a skilled radiographer. Always remember: the quality of your image directly impacts the accuracy of the diagnosis. By paying attention to positioning, anatomy, and evaluation criteria, you’ll ensure the best possible outcome for your patients.

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