What is the purpose and protocol of a Grashey view in evaluating shoulder joint conditions?

Grashey View: Purpose and Protocol

The Grashey view is a true anteroposterior (AP) radiograph of the glenohumeral joint obtained by rotating the patient 30-45° into a posterior oblique position, which profiles the glenohumeral joint space perpendicular to the x-ray beam and is essential as part of the minimum 3-view trauma protocol for evaluating shoulder pathology. 1, 2

Primary Purpose and Clinical Utility

The Grashey projection serves multiple critical diagnostic functions:

• Profiles the glenohumeral joint space by aligning the x-ray beam perpendicular to the scapula rather than the torso, eliminating the oblique projection that occurs with standard AP chest radiographs 1
• Demonstrates joint space narrowing and cartilage loss more accurately than conventional AP views, particularly for detecting osteoarthritis, sclerosis, osteophytes, cystic changes, tumors, and fractures 3, 4
• Significantly improves detection of rotator cuff tear findings compared to conventional AP views, including greater tuberosity sclerosis, greater tuberosity osteophytes, subacromial osteophytes, greater tuberosity cysts, and humeral head osteophytes (all P ≤ .013) 4
• Enables quantification of humeral head position relative to the glenoid, which can differentiate between normal shoulders, primary glenohumeral osteoarthritis (mean horizontal displacement angle 79.9°), and cuff tear arthropathy (mean vertical displacement angle 59.7°) compared to normal shoulders 5

Technical Protocol

Patient Positioning

• Turn the patient 30-45° into a posterior oblique position so the affected shoulder is rotated toward the x-ray cassette 1, 6
• This rotation aligns the scapula parallel to the cassette, making the glenohumeral joint perpendicular to the x-ray beam 1
• The patient can be positioned upright or supine depending on clinical circumstances 6

Standard Trauma Series Requirements

• The Grashey view must be combined with at least 2 other orthogonal views to constitute an adequate trauma protocol 1, 2
• Include either an axillary lateral view, scapular Y view, or both to evaluate for instability or dislocation 1
• The American College of Radiology recommends a minimum 3-view series: AP, Grashey, and axillary or scapular Y projections for all shoulder pain presentations 2, 7

Clinical Context and Diagnostic Superiority

Enhanced Detection Capabilities

The Grashey view demonstrates significantly superior sensitivity compared to conventional AP radiographs:

• Greater tuberosity sclerosis detection is significantly higher across all rotator cuff tear sizes (P < .001) 4
• Greater tuberosity osteophyte detection is especially prominent in medium-sized tears (P = .003) 4
• Subacromial osteophyte visualization is markedly better in medium and large to massive tears (P < .001) 4

Weighted Abduction Modification

• Adding weighted arm abduction during the Grashey position creates axial loading across the glenohumeral joint, which better demonstrates loss of articular cartilage that may not be apparent on standard Grashey views 3
• This modification is particularly useful when assessing cartilage integrity in suspected osteoarthritis 3

Common Pitfalls to Avoid

• Do not substitute a conventional AP chest view for a Grashey view, as the oblique projection of the glenohumeral joint on standard AP radiographs significantly reduces sensitivity for detecting pathology 4
• Do not skip the Grashey view in trauma protocols, as it is specifically recommended by the American College of Radiology as one of the minimum 3 required views 1, 2
• Exercise caution with axillary lateral positioning in patients with acute dislocation or recent reduction, as this positioning may be painful or lead to redislocation 1
• Recognize that the Grashey view is a screening tool, not a definitive diagnostic study—abnormal findings should prompt appropriate advanced imaging (MRI for soft tissue pathology, CT for fracture characterization) 2, 7

Integration into Diagnostic Algorithm

The Grashey view functions as part of the initial radiographic evaluation:

• All shoulder pain presentations should begin with plain radiographs including the Grashey view before proceeding to advanced imaging 2, 7
• If fracture is identified, proceed to CT without contrast for surgical planning 2, 7
• If rotator cuff pathology is suspected based on Grashey findings (greater tuberosity changes, subacromial osteophytes), proceed to MRI without contrast or ultrasound 2, 7
• If instability or dislocation is evident, MRI without contrast is the primary advanced study 2, 7