Shoulder: External Rotation

The External Rotation view is often the “anchor” of a shoulder series. This projection is designed to put the shoulder in its most anatomical position, providing a clear, unobstructed look at the greater tubercle. Because it opens the subacromial space, it is the primary view for evaluating the site of most rotator cuff attachments and checking for calcific tendonitis.

The Goal

To demonstrate the proximal humerus and shoulder girdle in a true anatomical position, profiling the greater tubercle laterally and opening the glenohumeral joint space.

Patient Positioning

The Setup: Place the patient in an upright position with their back against the bucky.
The Rotation: Have the patient drop their arm to their side and rotate the entire arm externally.
The Epicondyles: Instruct the patient to turn their palm forward until the epicondyles of the distal humerus are parallel to the plane of the IR.
Pro-Tip: If the patient is in too much pain to rotate their hand fully, have them lean their body slightly toward the affected side. This “cheats” the rotation of the shoulder girdle without putting as much stress on the joint itself.

Technical Factors

Central Ray (CR): Perpendicular to the IR, centered 1 inch inferior to the coracoid process.
SID: 40″.
Collimation: Ensure the field includes the superior soft tissue of the shoulder, the proximal third of the humerus, and the lateral two-thirds of the clavicle.

Image Evaluation Criteria (The “Richie” Checklist)

A high-quality External Rotation image must pass these checks:

Greater Tubercle in Profile: You should see the greater tubercle clearly profiled on the lateral aspect of the humeral head.
Lesser Tubercle Location: The lesser tubercle should be superimposed over the humeral head, located between the greater tubercle and the glenoid.
Joint Visualization: The glenohumeral joint space should be partially open, with the humeral head slightly overlapping the glenoid.
Sharp Detail: Sharp trabecular patterns must be visible in the humeral head. If the bone looks “grainy” or “blurred,” check for patient motion.
Marker Visibility: Your physical R/L marker must be clear and positioned in the lateral collimation field, away from any bony anatomy.

Why External Rotation Matters

This view is the diagnostic standard for identifying fractures of the greater tubercle, which are common in older patients following a fall. It also provides the best perspective for identifying calcium deposits in the supraspinatus tendon. Without this full external rotation, the greater tubercle rotates posteriorly, and these critical findings can be hidden behind the main body of the humeral head.

Richie’s Pro-Tips for External Rotation

Privacy and Security: Ensure the x-ray room door is closed and the patient is properly shielded with lead. A patient who feels secure and informed is much more likely to hold still for that critical “hold your breath” moment.

Watch the Palm: Many students think “palm forward” is enough, but some patients have very flexible wrists. Always check the elbow epicondyles to ensure the humerus itself has rotated, not just the hand.

Physical Markers Only: Digital markers are not legally or medically sufficient for orthopedic shoulder imaging. Always place your physical lead marker on the IR at the time of exposure.

The “Incomplete” Standard: Submitting a shoulder exam without a proper external rotation (unless a fracture makes rotation dangerous) is an ethical violation and a missed opportunity for diagnosis.