AP PROJECTION - EXTERNAL ROTATION: SHOULDER (NONTRAUMA)

X-ray of the Shoulder : AP View - External Rotation

When taking shoulder x-ray be warned to not to attempt to rotate arm if fracture or dislocations of the proximal humerus and shoulder girldle are demonstrated. This Projection may demonstrate calcium deposits in the muscles, tendonss, or bursal structures. Some pathologies, such as osteoporosis and ostearthritis, also may be demonstrated.

Technical Factors:

• IR - size 24 x 30 cm (10 x 12 inches), crosswise (or lengthwise to show more of humerus if injury includes proximal half of humerus)
• Moving or stationary grid
• 70 +- 5 kV range
• mAs 6

Shielding:

• Shield pelvic area.

Patient Position:

AP shoulder, external rotation humerus

• Perform radiograph with the patient in an erect or supine position. (The erect position is usually less painful for patient, if condition allows.) Rotate body slighly toward affected side if necessary to place shoulder in contact with IR or tabletop.

Part Position:

• Position patient to center scapulohumeral joint to center of IR.
• Abduct extended  arm slightly; then external rotate arm (supinate hand) until epicondyles of distal humerus are parallel to IR.

Central Ray:

• CR perpendicular to IR, directed to 1 inch (2.5cm) inferior to caracoid process (see note)
• Minimum SID of 40 inches (100cm)

Collimation:

• Collimate on foursides, with lateral and upper borders adjusted to soft tissue margins.

Respiration:

• Suspend respiration during exposure.

note: The coracoid process may be difficult to palpate directly on most patients, but it can be approximated; it is about 3/4inch (2cm) inferior to the lateral portion of the more readily palpated clavicle.


Radigraphic Criteria:

• Structure Shown:

• AP projection of proximal humerus and lateral two-thirds of the calvicle and upper scapula, including ralationship of the humeral head to the glenoid cavity.

AP shoulder, External Rotation

Position:

• Full external rotation is evidenced by the greater tubercle visualized in full profile on the lateral aspect of the proximal humerus. Lesser tubercle is superimposed over humerul head.

Collimation and CR:

• Collimation should be visible on four sides to the area of the affected shoulder.
• CR and the center of the collimation field should be at scapulohumeral joint.

Exposure Criteria:

• Optimum density and contrast with no motion will demonstrate clear, sharp bony trabecular markings with soft tissue detail visible for possible calcium deposits.