Scaphoid (PA axial view)

Mr Andrew Murphy et al.

The scaphoid PA axial view is part of a four view series of the scaphoid, wrist and surrounding carpal bones. It is a complementary projection to the PA view demonstrating the scaphoid free from superimposition.

  • patient is seated alongside the table
  • the affected arm if possible is flexed at 90° so the arm and wrist can rest on the table
  • the affected hand is placed, palm down on the image receptor with hand in ulnar deviation (see practical points)
  • shoulder, elbow, and wrist should all be in the transverse plane, perpendicular to the central beam
  • the wrist and elbow should be at shoulder height which makes radius and ulna parallel (lowering the arm makes radius cross the ulna and thus relative shortening of radius)
  • posteroanterior axial projection
  • centring point
    • anatomical snuffbox 
    • the central beam is angled 15-30 degrees proximally along the long axis of the arm towards the elbow
  • collimation
    • laterally to the skin margins
    • distal to the base of the first metacarpal 
    • proximal to the radiocarpal joint
  • orientation  
    • portrait
  • detector size
    • 18 cm x 24 cm
  • exposure
    • 55-65 kVp
    • 3-5 mAs
  • SID
    • 100 cm
  • grid
    • no
  • the scaphoid should appear slightly elongated almost free from all superimposition
  • minor superimposition of the metacarpal bases
  • articulation between the distal radius and the ulna is open or has little superimposition.

The scaphoid does not sit 100% flush with the image receptor when the hand is resting, as seen in figure 1, the scaphoid has a natural palmar tilt, therefore angling to that tilt will result in a 'truer' PA radiograph.  

It is important the remember why you are angling the central ray, and some patients will have little tolerance to the ulnar deviation, too much angle will only distort the scaphoid via superimposition. More often than not, if the scaphoid is profoundly elongated with overlaying anatomy you have angled too much. 

Patients with a fractured scaphoid will be in a lot of pain so deviating their hand to the ulna can be quite a task; only deviate the hand as much as the patient can bear it. 

Ulnar deviation is necessary as it moves the scaphoid away from the radius and rotates it in the palmer aspect, minimising superimposition and achieving a pure PA projection 1-3.

It is important to remember this when examining your patient, and it is easy to forget that only lifting your hand up and placing it on an image receptor could result in substantial pain. More often than not, the pain has not been addressed yet. Offer to move things around to assist in positioning, simple things like lowering/raising the table can go a long way and result in a better experience for the patient.

Radiographic views
Share article

Article information

rID: 47225
Section: Radiography
Synonyms or Alternate Spellings:

Support Radiopaedia and see fewer ads

Cases and figures

  • Drag
    Figure 1: orientation of the scaphoid
    Drag here to reorder.
  • Drag
    Figure 2: PA axial view
    Drag here to reorder.
  • Drag
    Figure 3: position for an axial view
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.