Week 9: Shoulder

• The shoulder girdle consists of the clavicle and scapula
• The shoulder girdle articulates with the head of the humerus laterally at the shoulder joint
• It also connects with the manubrium of the sternum medially at the sternoclavicular (SC) joint, and each other laterally at the acromioclavicular (AC) joint
• The shoulder girdle connects the upper limb to the trunk of the body
• The humerus is not considered part of the shoulder girdle, but the proximal humeral anatomy is considered during shoulder joint imaging
• The shoulder joint is a diarthrodial joint by function
• It is a synovial joint by anatomy/structure
• Capable of all motions as a ball-and-socket joint

Scapula

• Scapula is classified as a flat bone
• Forms the posterior portion of the shoulder girdle
• It is triangular in shape
• It has two surfaces: costal (anterior) and dorsal (posterior)
• Three borders: lateral, medial, and superior
• Three angles: superior, inferior, and lateral

General Procedural Guidelines for Shoulder Imaging

• Patient preparation includes removing radiopaque artifacts like jewelry and clothing artifacts
• Patient comfort is the priority, and procedures can be performed in upright or recumbent positions
• Shoulder and clavicle IR/Collimation size is 10 x 12 inches (24 x 30 cm), crosswise or lengthwise
• Scapula IR/Collimation size is 10 x 12 inches (24 x 30 cm), lengthwise
• Bilateral AC Joints IR/Collimation size is 14 x 17 inches (35 x 43 cm), crosswise
• Standard SID (Source to Image Distance) is 40 inches
• Use right or left side markers, avoiding digital annotation
• Use close collimation, gonad shielding (per state regulations), and optimal technique factors
• Explain/demonstrate positions and breathing instructions to the patient
• Suspend respiration for most exposures
• You can use a breathing technique for transthoracic lateral projections that involves low mA with long exposure time

Essential Shoulder Projections

• AP projections: internal rotation, external rotation, neutral position
• AP oblique (Grashey method)
• Transthoracic lateral (Lawrence method)
• Inferosuperior axial (Lawrence method)
• Supraspinatus Outlet (Neer Method)

AP Projection - Internal Rotation

• Position the patient to supine or upright
• Center the shoulder joint
• Slightly flex the elbow and internally rotate the arm, resting the back of the hand on the hip
• Place humeral epicondyles perpendicular to the IR
• Use a perpendicular central ray that enters 1 inch inferior to the coracoid process
• Using 10 x 12 inches (24 x 30 cm) IR/Collimation
• If crosswise: include 1.5 inches (3.8 cm) above the shoulder and 1 inch (2.5 cm) beyond the lateral aspect of shoulder, the sternal end of the clavicle, and the proximal third of humerus
• If lengthwise: include more humerus and less clavicle
• Shown bony and soft structures of the shoulder and proximal humerus

AP Projection - External Rotation

• Position patient to supine or upright
• Abduct arm slightly, flex elbow slightly, rotate arm externally, and supinate hand
• Place humeral epicondyles parallel to IR
• Use perpendicular central ray,entering 1 inch inferior to coracoid process
• Using 10 x 12 inches (24 x 30 cm) IR/Collimation
• If crosswise: include 1.5 inches (3.8 cm) above the shoulder and 1 inch (2.5 cm) beyond the lateral aspect of shoulder, the sternal end of the clavicle, and the proximal third of humerus
• If lengthwise, include more humerus, less clavicle
• Shows the bony and soft structures of the shoulder and proximal humerus

AP Projection - Neutral Position

• Used for trauma cases
• Leave the arm in the neutral position
• If possible, have the patient rest the palm of the hand against the thigh
• Places epicondyles at 45-degree angle to IR
• Direct the central ray (CR) the same as for other positions and also the collimation

AP Oblique (Grashey Method)

• Position supine or upright (RPO or LPO)
• Part Position: 35 to 45 degrees posterior oblique position, with the affected shoulder closer to IR
• You may need more rotation if patient is recumbent
• Rotate to place the scapula parallel to IR
• Head of humerus will be in contact with IR
• The arm position dictated by departmentprotocol or palm of the hand on the abdomen
• Direct the central ray (CR) perpendicular to glenoid cavity
• Entering 2 inches (5 cm) medial and inferior to superolateral border of shoulder
• Radiation field to 8 ×10 inch (18 × 24 cm)
• IF crosswise include 1.5 inch (3.8 cm) above the shoulder, 1 inch (2.5 cm) beyond the lateral aspect of the shoulder, the lateral half of the clavicle and the proximal third of the humerus
• IF lengthwise included, more humerus and less clavicle will be included
• Shows the Scapulohumeral or glenohumeral joint

Transthoracic Lateral (Lawrence Method)

• Note: This is used for trauma patients who cannot rotate or abduct arm.
• Patient Position: Supine, upright lateral, or dorsal decubitus
• With your affected limb closer to IR, have the unaffected limb elevated over head
• Part Position: Do not move injured limb, have the patient raise the non-injured arm, ensure elevated shoulder, is higher than injured shoulder, MCP perpendicular to the IR and Center surgical neck of humerus to IR
• Direct the central ray (CR) Perpendicular, entering MCP at surgical neck
• IF shoulders are in same plane, CR angled 10 to 15 degrees cephalad.
• Use the 10x12inches (24x30cm)
• The light field will appear smaller on the skin because of OID (Object to Image Distance) but do not collimate larger than stated size
• Complete the exposure made on inspiration or set a breathing technique i.e slow, deep breathing and a minimum exposure time of 3 seconds
• Shows through the Shoulder and proximal humerus projected through the thorax.
• Evaluation include the Scapula, clavicle, and humerus seen through the lung field, as well as the Scapula superimposed over the thoracic spine

Inferosuperior Axial Projection (Lawrence Method)

• Patient Position: Supine with the Head and shoulder elevated on 3-inch radiolucent support, the head turned away from CR
• Part position: abduct arm to right angle, place arm in external rotation if you can
• Place IR crosswise on the table (support in a holder or with sandbag) centered to your shoulder joint.
• Central Ray (CR): Horizontal, Medial angulation of 15 to 30 degrees
• Entering axilla; passes through AC joint and Angle depending on abduction of humerus, with More abduction = greater angle
• IR/Collimation: Radiation field 12 inches (30 cm) in width on the collimator and to 1 inch (2.5 cm) above the anterior shadow of the shoulder.
• Shows inferosuperior axial image off the proximal humerus and scapulohumeral Joint.
• Shows lateral portion of the coracoid process, with AC articulation and scapulohumeral joint, and Coracoid process shown clearly with Bony trabecular detail.

PA Oblique (Scapular Y)

• The acromion & coracoid process form a Y shape
• Best for diagnosing shoulder dislocations.
• In the normal shoulder, the humeral head is directly superimposed over the junction of the Y (acromion & coracoid)
• Patient position the patient Upright or recumbent, and RAO or LAO

Supraspinatus "Outlet" Neer Method (RAO or LAO)

• Patient placed in the position of seated or stand facing with vertical grid
• Central Ray is Angled 10-15 degrees caudal, entering the superior aspect of the humeral head.
• Depending for availability onIR is: 8x10 or 10x12 lengthwise
• Average degree of patient rotation is 45-60 degrees from plane of the IR
• Respiration is suspended during procedure
• Image shows the tangential outlet image shows the posterior surface of the acromion and the AC joint identified as the superior border of the coracoacrominal outlet
• Its required for the joint head to be projected below the AC joint and to be evidense of proper collimation