Shoulder (supine lateral view)

The supine lateral scapula view (anterior oblique AP) is a modified lateral shoulder projection often utilized in trauma imaging. Orthogonal to the AP shoulder (note so is an axillary view); It is a pertinent projection to assess suspected dislocations, scapula fractures and degenerative changes.

This projection is best suited to trauma patients who are not on spinal precautions, for patients on spinal precautions that require a lateral shoulder radiograph see modified supine lateral shoulder.

Patient position

• patient is supine
• the affected side of the patient is rolled anterior roughly 40 degrees, or, until the scapula is perceived to be end on this is aided by placing a 45 degree sponge under the rolled up side
• If possible the affected sides hand is placed across the thorax for additional rotation of the scapula into the lateral plane

Technical factors

• anteroposterior lateral projection
• centring point
  • the level of the glenohumeral joint at the center of the proximal humerus
  • straight tube to avoid elongation of anatomical structures
• collimation
  • laterally to include the skin margin
  • medially to cover the entirety of the medial scapula
  • superior to the skin margin
  • inferior to the inferior angle of the scapula
• orientation  
  • portrait                       
• detector size
  • 24 x 30 cm
• exposure
  • 60-70 kVp
  • 10-20 mAs
• SID
  • 100 cm
• grid
  • yes

Image technical evaluation

• this radiograph should have a similar appearance to the PA lateral scapular projection however to correct the image is the opposite to the PA
• the scapula is clearly demonstrated in a lateral profile, giving the clear appearance of a ‘Y’
• acromion and the coracoid process form the upper arms of the ‘Y’
• if intact, the humeral head is superimposed at the base of the ‘Y’

Practical points

The lateral scapula projection can be technically demanding, especially when patients are in pain. An anecdotal method amongst radiographers is to feel for the medial border of the scapula and line it up with the anterior portion of the acromion and x-ray straight down the line.

The idea being, if they are lined up there will be a superimposition of the medial and lateral borders of the scapula and hence a perfect lateral position, although this isn't always the case.

The best defense against positional errors is having a thorough understanding of radiographic anatomy and how it changes positionally when assessing for under/over rotation of the lateral shoulder, asses the borders of the scapula.

Over rotation

Over rotation in this projection refers to the patient's affected side sitting too far away from the image receptor, otherwise known as lying ‘too square’ to the detector.

Over-rotation is clearly established as the lateral border of the scapular (significantly thicker than the medial) is projected over the thorax along with the humeral head; to adjust this, rotated the affected side towards the image receptor slightly.

Under rotation

Under rotation in this projection refers to the patient's affected side sitting too close to the image receptor, otherwise known as lying ‘flat’ to the detector.

The lateral border, as well as the humeral head, will be sitting overly lateral in the image; to fix this, rotated the affected side away from the detector to increase obliquity.