Shoulder X-Ray Positioning: AP, Grashey, Y-View, and Axillary

Why Shoulder Positioning Deserves Special Attention

The shoulder is the most complex joint in the appendicular skeleton. With six degrees of freedom and a shallow glenoid fossa that accepts only about one-third of the humeral head, the glenohumeral joint relies almost entirely on soft tissues — the rotator cuff, labrum, and capsule — for stability. This anatomical design makes the shoulder both incredibly mobile and notoriously vulnerable to injury.

For the radiologic technologist, shoulder X-rays are among the most frequently ordered exams in both outpatient orthopedics and the emergency department. The ARRT exam routinely features questions on shoulder positioning, centering points, evaluation criteria, and the clinical rationale for each projection. A solid grasp of shoulder radiography is not optional — it's expected of every entry-level technologist.

This guide covers every standard projection of the shoulder: AP internal and external rotation, the Grashey (true AP) view, the scapular Y-view, the axillary lateral, and the trauma shoulder series. We will also cover the anatomy, centering points, technical factors, and evaluation criteria you need for clinical practice and the registry.

Relevant Shoulder Anatomy for Positioning

Before we discuss positioning, let's review the key bony landmarks you will need to locate by palpation. The ARRT exam frequently tests your knowledge of these anatomical reference points.

Key Bony Landmarks

• Coracoid process: A hook-shaped projection on the anterior scapula, palpable just inferior to the lateral third of the clavicle. This is your primary centering landmark for most shoulder projections — the CR is placed approximately 2.5 cm (1 inch) below it.
• Acromion process: The lateral extension of the scapular spine that forms the roof of the shoulder. Palpable as the bony point of the shoulder.
• Glenoid fossa: The shallow articular surface of the lateral scapula that articulates with the humeral head. It is oriented slightly anteriorly (approximately 35-45 degrees from the coronal plane), which is why the true AP (Grashey) requires rotation.
• Humeral head: The rounded proximal articular surface of the humerus. Its relationship to the glenoid determines whether the joint is reduced or dislocated.
• Greater and lesser tubercles: Bony prominences on the proximal humerus that serve as attachment points for the rotator cuff muscles. Their position on the AP view tells you whether the humerus is internally or externally rotated.
• Anatomical vs. surgical neck: The anatomical neck is at the joint capsule attachment; the surgical neck is the most commonly fractured region, distal to the tubercles.

AP Shoulder — Internal and External Rotation

The AP shoulder is the most common shoulder projection. It is performed in two different degrees of humeral rotation to evaluate different aspects of the proximal humerus and joint.

AP Shoulder (External Rotation)

Positioning: The patient is erect or supine with the affected shoulder against the IR. The patient rotates the arm so the palm faces forward (supination) — this externally rotates the humerus. The epicondyles are parallel to the IR. The patient's head is turned away from the affected side to reduce superimposition.

• IR size: 24 × 30 cm (10 × 12 inches), crosswise or lengthwise depending on patient size
• SID: 100-110 cm (40 inches)
• CR: Perpendicular, centered 2.5 cm (1 inch) inferior to the coracoid process
• Collimation: Tightly to the shoulder joint — superior above the acromion, medial to the midline, lateral to the skin margin
• Respiration: Suspended expiration (depresses the diaphragm and may reduce lung superimposition)
• Grid: Yes (stationary or moving), unless patient cannot cooperate

AP Shoulder (Internal Rotation)

Positioning: Same patient position, but the arm is rotated so the palm faces the thigh (pronation) — this internally rotates the humerus, bringing the greater tubercle into profile medially. The epicondyles are perpendicular (or nearly so) to the IR.

• CR and IR: Same as external rotation
• Differentiator: In external rotation, the greater tubercle is seen in profile laterally. In internal rotation, the greater tubercle projects medially and the lesser tubercle is seen in profile anteriorly

Evaluation Criteria for AP Shoulder

• The glenohumeral joint space is open (though not optimally — that's the Grashey view)
• The humeral head superimposes the glenoid fossa partially
• In external rotation: the greater tubercle is visible in lateral profile; the lesser tubercle is seen en face
• In internal rotation: the greater tubercle is superimposed over the humeral head medially; the lesser tubercle is seen in profile
• The surgical neck and proximal humeral shaft are well visualized
• No rotation of the thorax (spinous processes should be equidistant from the clavicles if centered)

The Grashey View (True AP / AP Oblique)

The Grashey view, also called the true AP or AP oblique of the shoulder, is arguably the most important single projection for evaluating the glenohumeral joint. Named after Dr. Grashey, this view rotates the patient so the X-ray beam passes directly through the joint space, eliminating the superimposition of the humeral head on the glenoid.

Why it matters: On a standard AP shoulder, the humeral head is superimposed over the posterior glenoid rim because of the glenoid's 35-45 degree anterior orientation. The Grashey view opens the joint space, allowing evaluation of joint space narrowing, osteoarthritis, and fracture lines through the glenoid.

Positioning for the Grashey View

• Patient position: The patient stands or sits with the affected shoulder against the IR. The body is rotated 35-45 degrees toward the affected shoulder (the patient's unaffected side lifts away from the IR). This rotation aligns the glenoid fossa parallel to the IR.
• Arm position: The affected arm is externally rotated (palm forward) if possible. The elbow is slightly flexed and the hand rests on the hip or a support.
• CR: Perpendicular to the IR, centered to the glenohumeral joint — approximately 2.5 cm inferior to the coracoid process and slightly medial
• IR: 24 × 30 cm (10 × 12 inches) lengthwise or crosswise
• SID: 100-110 cm (40 inches)

Evaluation Criteria for Grashey View

• The glenohumeral joint space is open — a radiolucent gap is visible between the humeral head and the glenoid fossa
• The anterior and posterior glenoid rims are superimposed (seen as a single line)
• The coracoid process is projected medially and does NOT superimpose the glenoid
• The acromion and acromioclavicular (AC) joint are visible superiorly
• Adequate penetration of the glenohumeral joint without overexposure of the soft tissues

Scapular Y-View (Lateral Scapula)

The scapular Y-view is an essential projection for evaluating shoulder dislocation. The "Y" refers to the shape formed by the scapular body (the vertical limb), the acromion process (the superior limb), and the coracoid process (the inferior-medial limb). In a normal, reduced shoulder, the humeral head projects directly over the intersection of the Y. In anterior dislocation — the most common type (95% of shoulder dislocations) — the humeral head is displaced anteriorly and inferiorly, appearing below the Y or anterior to it.

Scapular Y Positioning (Anterior Oblique)

• Technique 1 — PA oblique (most common): The patient faces the IR with the affected shoulder closest to the IR. The body is rotated 45-60 degrees toward the affected side (so the scapula is perpendicular to the IR). The affected arm is placed across the patient's chest (internal rotation), which pulls the scapula laterally for better visualization.
• Technique 2 — AP oblique: The patient's back is to the IR, rotated 45-60 degrees toward the affected side. This is used when the patient cannot stand or face the IR.
• CR: Perpendicular, centered to the scapulohumeral joint — approximately 2.5-5 cm (1-2 inches) inferior to the acromion, at the level of the intersection of the Y
• IR: 24 × 30 cm (10 × 12 inches) lengthwise
• SID: 100-110 cm (40 inches)
• Respiration: Suspended

Evaluation Criteria for Scapular Y-View

• The three limbs of the scapular Y are clearly visible
• The humeral head is superimposed over the Y intersection (normal) or displaced (dislocation)
• The scapula is seen without superimposition of the ribs (proper rotation achieved)
• The proximal humerus and surgical neck are visualized
• No motion blur (adequate exposure time)

Axillary Lateral Shoulder View

The axillary lateral view provides a true lateral projection of the glenohumeral joint and is the best view for determining the direction of a dislocation. It also provides excellent visualization of the glenoid rim, the coracoid, and the acromion. However, it requires the patient to abduct the arm 90 degrees — which may be impossible in acute trauma or in elderly patients with limited mobility.

Axillary Lateral Positioning

• Supine technique: The patient is supine with the affected arm abducted 90 degrees (or as close to 90 as possible). The elbow is bent at 90 degrees with the forearm pointing upward. The IR is placed superior to the shoulder, resting against the neck or on a support.
• CR: Directed inferiorly through the axilla, angled 15-30 degrees toward the shoulder joint (depending on patient habitus). The CR enters the axilla and exits at the top of the shoulder.
• SID: 100 cm (40 inches)
• IR: 24 × 30 cm (10 × 12 inches) placed against the superior-lateral aspect of the shoulder
• Alternative — seated technique: The patient leans backward slightly (10-15 degrees) with the affected arm abducted. The CR passes through the axilla, angled 15-20 degrees anterior to the coronal plane.

Evaluation Criteria for Axillary Lateral

• The humeral head is seen in true lateral profile relative to the glenoid fossa
• The acromion and coracoid process are visible, confirming the anterior aspect of the shoulder
• The glenoid rim is visualized without superimposition
• The joint space is open and the relationship between the humeral head and glenoid is clear
• The humeral head should be centered within the glenoid fossa (normal alignment)

Comparison Table: Shoulder Projections at a Glance

Shoulder Trauma Series Protocol

In the emergency setting, the shoulder trauma series follows a specific protocol designed to answer two questions: (1) Is there a fracture? and (2) Is there a dislocation? The standard three-view trauma series typically includes:

1. AP shoulder (external or internal rotation) — screens for proximal humerus fractures and gross dislocation
2. Grashey (true AP) — evaluates the glenohumeral joint space and glenoid rim
3. Scapular Y-view — confirms or rules out dislocation by assessing humeral head position relative to the Y intersection

When the patient presents with a known or suspected dislocation and can tolerate arm abduction, the axillary lateral is added as a fourth view to determine the direction of dislocation and assess for fractures of the glenoid rim (Bankart lesions).

Trauma Positioning Considerations

Working with trauma patients requires special considerations:

• Do not force a painful extremity into external rotation. If the patient cannot externally rotate the arm, perform the AP in the position of comfort — it will be an internal rotation or neutral AP. Document accordingly.
• For the Grashey view in trauma: If the patient cannot stand, rotate the entire supine patient (logroll onto a sponge or lift the unaffected side with sheets). Alternatively, perform an AP oblique by rotating the tube 35-45 degrees (though this is a compromise).
• Cross-table lateral: If the Y-view and axillary are not possible due to patient immobility, a cross-table lateral can be performed with the patient supine and the CR directed horizontally through the axilla.
• Immobilize above all else: In suspected fracture or dislocation, never move the injured arm more than necessary. Your primary goal is diagnostic images without causing further harm.

Neer Views and Other Special Projections

Beyond the standard views, several specialized projections are used in specific clinical contexts:

Neer View (Supraspinatus Outlet View)

The Neer view is a modified Y-view with the CR angled 10-15 degrees caudad. It profiles the supraspinatus outlet and is used to evaluate the acromiohumeral interval and identify subacromial impingement or calcific tendinitis. Positioning: patient similar to Y-view, but tube angled caudally.

Stryker Notch View

Used to evaluate for Hill-Sachs lesions (compression fractures of the posterolateral humeral head caused by anterior dislocation). The patient is supine with the hand on the top of the head, and the CR is angled 10 degrees cephalad.

West Point View

An axillary variation for evaluating the anteroinferior glenoid rim for Bankart lesions. The patient is prone with the affected arm abducted 90 degrees and the CR angled 25 degrees medially and 25 degrees caudad.

Common Positioning Errors and How to Avoid Them

Technical Factors Reference Table

Note: Technique values are approximate and depend on patient habitus, grid ratio, and equipment calibration. Always follow your department's established technique chart. The table assumes an 8:1 grid — reduce mAs by a factor of 2-4 if no grid is used.

Key Takeaways for Clinical Practice and the ARRT

1. The Grashey view requires body rotation, not tube angulation. Rotate the patient 35-45 degrees toward the affected shoulder.
2. The scapular Y-view is the dislocation screen. A humeral head over the Y intersection = reduced. Displaced = dislocated.
3. The axillary lateral is the gold standard for dislocation direction. Only performed if the patient can abduct the arm 90 degrees.
4. External rotation profiles the greater tubercle; internal rotation profiles the lesser tubercle.
5. Never force a trauma patient's shoulder into an uncomfortable position. Image in the position of comfort and document the rotation used.
6. Master the landmarks: coracoid process (centering landmark), acromion, and the Y intersection are your most important palpation points.
7. Hill-Sachs → Stryker notch view. Bankart → West Point view. Know these associations cold for the registry.