Elbow (external oblique view)

The elbow external oblique view is an additional projection of the elbow often used to better demonstrate the radial head free from superposition.

Indications

This external oblique view is an additional projection often used to separate the proximal radius from the ulna for closer inspection of structures such as the radial head.

Patient position

• patient is seated alongside the table

• the fully extended arm and forearm, in a supinated position, are kept in contact with the table by lowering the shoulder joint to the level of the table they all must be in the same plane as the detector 

• the patient externally rotates the arm to isolate the radial head

• the detector is placed below the elbow joint

Technical factors

• anteroposterior external oblique projection

• centering point

  • mid elbow which is approximately the midpoint between the epicondyles 

• collimation

  • superior to the distal third of the humerus

  • inferior to include one-third of the proximal radius and ulna

  • lateral to include the skin margin 

  • medial to include medial skin margin 

• orientation  

  • portrait

• detector size

  • 18 cm x 24 cm

• exposure

  • 50-60 kVp

  • 2-5 mAs

• SID

  • 100 cm

• grid

  • no 

Image technical evaluation

• the elbow is in an external oblique project position

• patient's arm should be rotated externally more so than the AP projection so the radial head is free from superposition

Practical points

Patients with true radial head fractures/injuries of the elbow will find it very hard to externally oblique for the projection, it's best to encourage the patient to rotate from their shoulder. Therefore, not isolating the elbow joint, often this involves the patient leaning toward the side of obliquity.