Elbow Axiolateral, Coyle (Coronoid Process) is a radiography positioning projection of the Upper Extremity. Elbow flexed 80 degrees, palm flat on IR. CR angled 45 degrees away from shoulder. The centering point is located mid-elbow joint. Elbow flexed 80 degrees, palm flat on IR. The central ray is CR angled 45 degrees away from the shoulder, into the mid-elbow joint. Image-quality criteria include coronoid process of the ulna in profile, free of the radial head, open humeroulnar joint space. The SID is 40 inches (102 cm).
Anatomy demonstrated
- Coronoid process in profile.
- Trochlea of the humerus.
- Open humeroulnar joint.
- Distal humerus, distorted by the 45-degree angle.
- Proximal radius, with the head and neck superimposed by the ulna.
Patient preparation
- WARNING: with possible spinal injury or severe trauma, do not attempt to move the patient; do not rotate a severely injured part or remove splints (Bontrager). Merrill's: do not attempt true AP or lateral positioning of a severely injured limb; take two projections 90 degrees apart, moving it as little as possible, and move the IR and tube if the patient cannot reach the position.
- Verify patient identity using two identifiers.
- Remove watches, bracelets, and radiopaque items from the arm.
- Seat the patient at the end of the table, or for trauma position supine on the table or cart.
- Flex the elbow 80 degrees with the palm flat against the IR.
- Adjust so humerus, elbow, and wrist sit in the same plane.
Position & centering point
Mid-elbow joint. Elbow flexed 80 degrees, palm flat on IR.
Central ray
CR angled 45 degrees away from the shoulder, into the mid-elbow joint.
Exposure / technique
- kVp
- N/A
- mAs
- N/A
- SID
- 40" (102 cm)
- Notes
- Pairs with the radial-head Coyle when the patient cannot fully extend the elbow for the medial or lateral oblique projections. In trauma, supine on the table or cart with a horizontal CR (Merrill's) directed caudad 45 degrees. Bontrager digital range: 65 to 75 kV, adding 4 to 6 kV from the lateral elbow because of the angled CR. Neither Bontrager nor Merrill's prints mAs for this projection.
Image-quality criteria
- Coronoid process of the ulna in profile, free of the radial head.
- Open humeroulnar joint space.
- Trochlea visible.
- Distal humerus and proximal forearm both included.
- Bone trabeculae sharp, no motion blur.
- Collimation: 3 inches proximal and distal to the joint.
Common errors
- 1 CR not angled 45 degrees from the shoulder into the mid-elbow joint.
- 2 Tube angled toward instead of away from the shoulder gives the radial-head view.
- 3 Elbow flexed more than 80 degrees, which may obscure the coronoid process.
- 4 Hand not pronated.
Clinical indications
- Suspected coronoid process fracture.
- Patient unable to extend the elbow for a true AP oblique.