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Upper Extremities

17 Wrist

Anatomy

Key Structures

  • Carpals (8 total)
    • Proximal row (lateral → medial): Scaphoid, Lunate, Triquetrum, Pisiform
    • Distal row (lateral → medial): Trapezium, Trapezoid, Capitate, Hamate
  • Articulations: Radiocarpal joint, Ulnocarpal articulation, Intercarpal joints, Carpometacarpal joints, Distal radioulnar joint
  • Other features: Radial styloid process, Ulnar styloid process, Anatomic snuffbox, Carpal tunnel (carpal canal)

Common Pathologies

  • Scaphoid fracture – most common carpal fracture; tenderness in anatomic snuffbox
  • Colles’ fracture – distal radius fracture with dorsal displacement (fall on outstretched hand)
  • Smith’s fracture – distal radius fracture with volar displacement (fall on flexed wrist)
  • Barton’s fracture – intra-articular distal radius fracture involving the radiocarpal joint
  • Triquetral fracture – often from hyperextension injuries
  • Carpal tunnel syndrome – compression of the median nerve within carpal canal
  • Hamate hook fracture – common in golfers and racquet sports
  • Ulnar variance abnormalities – positive/negative ulnar variance can affect ulnocarpal loading

Standard Projections (ARRT Required)

Wrist – PA Projection

CR Location & Positioning

  • SID: 40″
  • Patient position: Seated at table with shoulder, elbow, and wrist in the same plane
  • Adjustments: Rest forearm on table, pronate hand, flex digits slightly to bring carpals in close contact with IR (reducing OID)
  • CR: Perpendicular to midcarpal area
  • Pt. Instructions: Hold still
  • Exposure: 60–65 kVp, 2–3 mAs (digital)

Evaluation Criteria

  • Coverage: Distal radius and ulna, carpals, and proximal half of metacarpals
  • Rotation checks: Equal concavity on both sides of metacarpal shafts; minimal overlap at distal radioulnar joint
  • Motion checks: Sharp cortical margins and trabecular pattern
  • Technique checks: Open radioulnar joint; soft-tissue detail visible
  • Clinical aim: Baseline wrist assessment; used for comparison in injury and pathology detection

Wrist – PA Oblique (Lateral Rotation)

CR Location & Positioning

  • SID: 40″
  • Patient position: Seated, forearm resting on table, shoulder in same plane
  • Adjustments: From pronated position, rotate wrist laterally 45° using foam wedge; extend digits slightly to open joint spaces
  • CR: Perpendicular to midcarpal area (enters just distal to radius)
  • Pt. Instructions: Hold still
  • Exposure: 60–65 kVp, 2–3 mAs

Evaluation Criteria

  • Coverage: Distal radius and ulna, carpals, and proximal metacarpals
  • Rotation checks: Slight overlap of distal radius and ulna; trapezium and distal scaphoid free of superimposition
  • Motion checks: Sharp trabecular markings
  • Technique checks: Open trapeziotrapezoid and scaphotrapezial joint spaces
  • Clinical aim: Demonstrates lateral carpals (trapezium and scaphoid)

Wrist – Lateral (Lateromedial)

CR Location & Positioning

  • SID: 40″
  • Patient position: Seated, elbow flexed 90°, wrist in true lateral position
  • Adjustments: Align forearm, wrist, and hand in same plane; thumb up; ensure radius and ulna are superimposed
  • CR: Perpendicular to midcarpal area
  • Pt. Instructions: Hold still
  • Exposure: 60–65 kVp, 2–3 mAs

Evaluation Criteria

  • Coverage: Distal radius and ulna, carpals, and proximal metacarpals
  • Rotation checks: Distal radius and ulna superimposed; 2nd–5th metacarpals superimposed
  • Motion checks: Crisp cortical outlines
  • Technique checks: Correct contrast; visualize fat pads for subtle pathology
  • Clinical aim: Evaluate carpal alignment and displacement; useful for Colles’, Smith’s, Barton’s fractures

Specialty (Supplemental) Projections

Wrist – PA Ulnar Deviation

Indication: Scaphoid fracture, wrist trauma, snuffbox tenderness
CR Location & Positioning

  • SID: 40″
  • Adjustments: From PA wrist, deviate hand ulnarward without forearm rotation
  • CR: Angled 10°–15° proximally (toward elbow), centered to scaphoid (2 cm distal and medial to radial styloid)
  • Exposure: 60–65 kVp, 2–3 mAs

Evaluation Criteria

  • Scaphoid elongated and free of foreshortening
  • Open carpal spaces around scaphoid
  • Evident ulnar deviation (radius–metacarpal angle)

Wrist – PA Axial (Stecher Method)

Indication: Alternate scaphoid evaluation
CR Location & Positioning

  • SID: 40″
  • Adjustments: Wrist placed PA with IR elevated 20° at finger end (or CR angled 20° toward elbow)
  • CR: Perpendicular to scaphoid
  • Exposure: 60–65 kVp, 2–3 mAs

Evaluation Criteria

  • Scaphoid in profile with open articulations
  • No rotation; soft tissue and trabecular pattern visible

Wrist – Tangential (Gaynor-Hart Method)

Indication: Suspected hamate hook, pisiform, or carpal tunnel pathology
CR Location & Positioning

  • SID: 40″
  • Adjustments: Hyperextend wrist; rotate hand slightly toward radial side to prevent overlap; hold extended with opposite hand
  • CR: 25°–30° to long axis of hand, directed 1 inch distal to base of third metacarpal
  • Exposure: 65–70 kVp, 3 mAs

Evaluation Criteria

  • Pisiform and hamulus of hamate in profile, separated
  • Rounded palmar contours of capitate and scaphoid visualized
  • Carpal canal visible

 

Hows & Whys of Wrist Radiography

Anatomy

  • Which bones form the proximal and distal rows of the wrist?
    The proximal row (lateral to medial) includes the scaphoid, lunate, triquetrum, and pisiform.
    The distal row includes the trapezium, trapezoid, capitate, and hamate.
  • Which bones articulate at the radiocarpal (wrist) joint?
    The distal radius articulates with the scaphoid and lunate; the ulna does not directly articulate but connects via the triangular fibrocartilage complex (TFCC).
  • What carpal bone forms the floor of the anatomic snuffbox, and why is that important?
    The scaphoid; tenderness in this area is a clinical sign of a possible scaphoid fracture.
  • Which carpal articulates with the base of the first metacarpal?
    The trapezium, forming the thumb carpometacarpal joint that allows opposition and flexion-extension.
  • Which carpal bone contains a hook-like process, and what is its clinical significance?
    The hamate; the hook (hamulus) is often involved in fractures visible on the Gaynor-Hart projection.

Positioning

  • Why are the fingers flexed for a PA wrist projection?
    Flexing the fingers reduces OID by bringing the carpals into direct contact with the IR, improving spatial resolution.
  • Why is the hand rotated laterally 45° for a PA oblique wrist?
    To demonstrate the lateral carpals (trapezium and scaphoid) with minimal overlap of adjacent bones.
  • Why is a foam wedge often used for the oblique projection?
    It standardizes the 45° angle and prevents over-rotation or collapse of the wrist position during exposure.
  • Why is the elbow flexed 90° for the lateral projection?
    To align the radius and ulna vertically and achieve true superimposition without pronation or supination errors.
  • Why is ulnar deviation used for scaphoid imaging?
    It elongates the scaphoid and opens joint spaces between the scaphoid and adjacent carpals to better reveal fractures.
  • Why is the CR angled 10–15° proximally for a PA ulnar deviation view?
    This projects the scaphoid free of self-superimposition and enhances visibility of fracture lines.
  • Why is the IR angled 20° for the Stecher method?
    The angled IR makes the scaphoid perpendicular to the beam, minimizing foreshortening without requiring tube angulation.
  • Why is the wrist hyperextended and CR angled 25–30° for the Gaynor-Hart (carpal canal) projection?
    To tangentially project the carpal tunnel, separating the pisiform and hamulus for visualization of tunnel pathology.

Technique & Image Evaluation

  • How can you tell a PA wrist is not rotated?
    There is equal concavity of the metacarpal shafts, equal spacing between proximal metacarpals, and minimal overlap at the distal radioulnar joint.
  • How can you tell a PA oblique wrist was correctly positioned at 45°?
    The trapezium and distal scaphoid are visualized with minimal superimposition, and the 3rd–5th metacarpal bases are partially overlapped.
  • How can you tell the lateral wrist is truly lateral?
    The distal radius and ulna are perfectly superimposed, and metacarpals 2–5 overlap completely.
  • How can you tell there was adequate ulnar deviation on a scaphoid view?
    The scaphoid appears elongated with open joint spaces, and the long axis of the metacarpals forms a wide angle with the radius and ulna.
  • How can you tell the CR angle for the PA axial (Stecher) was correct?
    The scaphoid is seen without foreshortening, and adjacent carpal articulations are clearly open.
  • How can you tell a Gaynor-Hart projection is properly positioned?
    The pisiform is in profile and separated from the hamulus; the carpal bones form a distinct arch representing the canal.
  • How do you identify motion or poor technique?
    Cortical bone margins and trabecular detail appear blurred; repeat with improved immobilization or shorter exposure time.
  • How do you know the exposure technique was adequate for DR imaging?
    Soft-tissue outlines and fine trabecular patterns are visible without saturation; brightness and contrast are consistent across carpal and distal radial regions.

Clinical Applications

  • Which projection is best to evaluate a suspected scaphoid fracture when routine views are inconclusive?
    PA ulnar deviation with 10–15° proximal CR angle and/or PA axial (Stecher) projection.
  • Which projection demonstrates the carpal tunnel for suspected median nerve impingement?
    Tangential carpal canal (Gaynor-Hart).
  • Which projection helps assess anterior or posterior displacement in Colles’ or Smith fractures?
    Lateral wrist projection.
  • Why might the Rafert-Long series be performed after a negative routine wrist exam?
    To assess the scaphoid at multiple CR angles (0°, 10°, 20°, 30°) for subtle, non-displaced fractures invisible on standard views.

 

 

License

Radiographic Procedures Review Guide Copyright © 2025 by Carla M. Allen and Taylor M. Otto. All Rights Reserved.