Shoulder ultrasound: how to perform and interpret it

A practical guide to positioning and scanning sequence so a relevant finding doesn't get missed during a shoulder exam.

The shoulder is one of the most commonly examined joints by ultrasound, but it's also one of the ones that depends most on a systematic protocol — the region's superficial, mobile anatomy makes dynamic scanning easy, but it also makes it easy to miss a structure if the scan doesn't follow a fixed sequence.

Patient positioning

Sitting with the arm internally rotated and the hand resting on the back pocket (the modified Crass position) exposes the supraspinatus tendon well along its course. Evaluating the biceps tendon in the bicipital groove and the subscapularis, on the other hand, calls for the arm in neutral or slight external rotation, with the elbow resting at the side of the body.

Scanning sequence

A reproducible sequence — biceps, subscapularis, supraspinatus, infraspinatus and the acromioclavicular joint, ending at the subacromial-subdeltoid bursa — reduces the chance of skipping a structure, especially in exams performed under time pressure.

The value of dynamic assessment

Unlike MRI, ultrasound allows the shoulder to be moved during image acquisition. Abduction and rotation maneuvers reveal subacromial impingement and biceps tendon instability in the groove that a static image alone would not show.

Incidental versus relevant finding

Mild, heterogeneous thickening of the rotator cuff is a common finding in middle-aged and older patients, often asymptomatic. The clinical relevance of a finding always depends on correlating it with the patient's complaint — localized pain, specific weakness, trauma history — not on the isolated presence of an imaging change.