AP ACROMIOCLAVICULAR JOINTS

AP PROJECTION: AC JOINTS

ALEXANDER METHOD ALTERNATIVE

BILATERAL WITH AND WITHOUT WEIGHTS

Warning: Shoulder and/or clavicle projection should be completed first to rule out fracture, or this radiograph may be taken without weights first and check before it is taken with weights

Pathology Demonstrated in AP AC joints:

• Acromioclavicular joints separation is demonstrated.
• Widening of the joints space, as compared with the other view weights, usually indicates an AC joint separation.

Technical Factors:

AP View AC Joints

• IR size - 35 x 43 cm (14 x 17 inches), crosswise, or 7 x 17 inches (14 x 43 cm), if available
  "with weight" and "without weight"markers
• Bucky or non-grid (depending on size of shoulder)
• AEC not recommended
• 65 +- 5 kV with screen; 65 - 70 kV with grid on larger patients
• For broad shouldered patients, two 18 x 24-cm (8 x 10 inches) cassette crosswise, place side by side and exposed simultaneously to include both AC joints on a single exposure.

Shielding:

• Secure gonadal shield around waist.
• Patient Position in AP Acromioclavicular Joints
• Perform radiograph with the patient in an erect position, posterior shoulder against cassette with equal weight on both feet; arms at side; no rotation of shoulders or pelvis; and looking straight ahead.
• (May be taken seated if patient's condition requires.) Two sets of bilateral AC joints are taken in the same position, one without weights and one stress view with weight.

Part Position:

• Position patient to direct CR to midway between AC joints,
• Center midline of IR(s) to CR (top of IR should be <2 inch [5 cm] above shoulder).

Central Ray:

• CR perpendicular to a midpoint between AC joints, 1 inch (2.5 cm) above jagular notch (see note)
• Minimum SID of 72 inches (180 cm)

Collimation:

• Collimate with a long, narrow light field to area of interest; uppper light border should be to upper shoulder soft tissue margins.
• Respiration in AP Acromioclavicular Joints:
• Suspend respiration during exposure.

Weights Use:

• After the first exposure in AP Acromioclavicular joints is made without weights and the cassette(s) has (have) been changed, for large adult patients, strap 8 to 10 pounds minimum weights to each wrist, and, with shoulders relaxed, gently allow weights to hang from wrist while pulling down on each arm and shoulder.
• The same amounts of weight must be used on each wrist. Less weight (5 to 8 pounds per limb) may be used for smaller or asthenic patients and move weight for larger or hypersthenic patients, (Check department protocol for the quantity of applied weights.)

Note: Patient should NOT be asked to hold onto the weights with their hands; rather, the weights should be attached to the wrists so that the hands, arms, and shoulders are relaxed and possible AC joint separation can be determined. Holding on to weights may used in false-negative radiograph because they tend to pull on the weights, resulting in contraction rather than relaxation of the shoulder muscles.

Alternative AP axial projection:

ALEXANDER METHOD

• A 15degrees cephalic angle centered to the level of the AC joints projects the AC joint superior to the acromion, providing optimal visualization.

Alexander Method 15° cephalic CR

Alternative Supine Position AC Joints:

• If the patient's condition requires, the radiograph may be taken supine by trying both ends of a long strip of gauze to patient's wrists and placing around pateint's feet with knees patially flexed, then slowly and gently straightening legs and pulling down on shoulders.
• Also may be performed by an assistant who gently pulls down on arm and shoulders.

Warning: This method should be used only by experienced and qualified personnel a Registered Radiologic Technologist to prevent additional injury.
Radiographic Criteria:
Structure Shown in AC Joints:

• Both Acromioclavicular joints, as well as the entire clavicles and SC are demonstrated.

Position:

• Both AC joints are on the same horizontal plane.
• No rotation occurred, as is evidenced by symmetric appearance of the SC joint on each side of the vertibral column.

Collimation and Centra Ray (CR):

• Collimation should be visible on four sides, remembering to include both AC joints.
• CR and center of the collimation field should be at the midpoint between the AC joints.

Exposure Criteria and Markers:

• Optimal density and contrast will clearly demonstrate the AC joints and soft tissue without excessive density. Bony margins and trabecular markings will appear sharp, indicating no motion.
  Right and left markers, as well as markers indicating with and without weights, should be visible without superimposing essential anatomy.