Shoulder Ultrasound (Rotator Cuff)

1. 1

   Patient seated on a stool facing you. Use high-frequency linear probe (10–18 MHz) with plenty of gel.

2. 2

   Biceps tendon: arm in neutral, elbow flexed 90°. Probe transverse in the bicipital groove — identify as round echogenic structure. Rotate longitudinal to assess continuity.

3. 3

   Subscapularis: internally rotate arm (palm up on thigh). Transverse then longitudinal scan of the subscapularis tendon.

4. 4

   Supraspinatus — modified Crass position: patient places hand in back pocket (internally rotated). Probe coronal on the anterior shoulder. Long axis first, then short axis.

5. 5

   Infraspinatus: arm in neutral, probe at posterior shoulder lateral to spine of scapula. Long and short axis.

6. 6

   Subacromial-subdeltoid bursa: thin anechoic line between cuff and deltoid. Any fluid >2mm = bursitis.

7. 7

   Dynamic assessment: slowly abduct the arm while scanning — observe for impingement of cuff against acromion.

• Biceps tendon — transverse (long axis groove)
• Biceps tendon — longitudinal
• Subscapularis tendon — transverse + longitudinal
• Supraspinatus tendon — long axis (modified Crass)
• Supraspinatus tendon — short axis
• Infraspinatus tendon — long + short axis
• AC joint — transverse
• Subacromial-subdeltoid bursa
• Dynamic impingement (arm elevation)

• Supraspinatus continuity and echogenicity
• Bursal and articular surface tears
• Tendon thickness
• Biceps tendon integrity and position
• Subdeltoid bursal fluid
• Calcific deposits

• Anisotropy artifact mimics tears — always scan perpendicular to tendon fibers
• Tendon thickness must be compared to contralateral side
• Full-thickness tears: absent tendon, 'naked tuberosity' sign
• Patient must be in standard position (modified Crass for supraspinatus)

Modified Crass position: arm internally rotated, hand on ipsilateral back pocket. This stretches supraspinatus for best visualization. Dynamic assessment during arm elevation can provoke impingement.