Why Is Musculoskeletal Ultrasound Performed During Movement?

One of the major advantages of musculoskeletal ultrasound is the ability to observe tissues while they move. A tendon, nerve or part of a joint may look normal at rest but move abnormally, impinge on a neighbouring structure or reproduce a characteristic snap only in a specific position.

Polish version · For Patients

A static image answers only part of the question

MRI and CT provide extensive anatomical information, but they usually show the body in a fixed position. Ultrasound can be performed while the patient or examiner moves the joint. This means the examination can assess not only how a structure looks, but also how it behaves.

The movement should not be arbitrary. It should be chosen from the history and clinical examination to reproduce the position in which pain, clicking, locking or snapping occurs. Dynamic imaging is most useful when it answers a specific clinical question.

What can dynamic ultrasound reveal?

Tendon movement

During movement, ultrasound can assess structures such as the long head of the biceps tendon in the bicipital groove and the peroneal tendons behind the lateral malleolus. A brief subluxation may not be visible while the joint is held still.

A snapping nerve

The ulnar nerve may appear stable with the elbow extended but move over the medial epicondyle during flexion. Ultrasound can show the exact moment of displacement and help determine whether it corresponds to the patient’s snapping sensation. Movement alone is not necessarily abnormal; it has to be interpreted together with symptoms and the condition of the nerve.

Impingement during a specific movement

In selected situations, ultrasound can show the behaviour of tissues beneath the acromion, hand tendons, the iliotibial band or structures responsible for snapping around the hip. The image may help explain a mechanical phenomenon, but it should not be interpreted without considering pain and function.

What does the dynamic part of the examination look like?

The anatomy is first assessed at rest. The probe is then kept over the structure of interest while the patient performs a defined movement, sometimes slowly and sometimes against gentle resistance. The manoeuvre can be repeated from another angle or compared with the other side, remembering that asymmetry does not automatically mean pathology.

Why is “it snapped on ultrasound” not enough?

Some tendons and nerves move or sublux even in people without pain. Conversely, significant symptoms can arise from structures that ultrasound cannot assess sufficiently well. The finding therefore has to be integrated with the exact location of symptoms, injury mechanism, clinical tests and, when appropriate, X-ray, MRI or CT.

Probe position, movement speed, muscle tension and examiner experience also affect the assessment. An overly forceful manoeuvre can unnecessarily increase pain, while the wrong movement may fail to reproduce the problem.

When is dynamic assessment particularly useful?

• when clicking or snapping occurs only in a specific position;
• when intermittent tendon or nerve subluxation is suspected;
• when symptoms change with muscle contraction;
• when the aim is to distinguish smooth tissue gliding from mechanical conflict;
• when a static image does not explain a reproducible symptom.

Key point for an orthopaedic surgeon

Dynamic ultrasound is not a separate “better test”. It is a way of using ultrasound to answer a question about tissue behaviour. Its greatest value comes when the movement is selected to reproduce the symptom and the observed mechanism fits the clinical examination.

References

1. American College of Radiology, American Institute of Ultrasound in Medicine and collaborating societies. Practice Parameter for the Performance of a Musculoskeletal Ultrasound Examination. ACR–AIUM practice parameter.
2. Fodor D, et al. The EFSUMB Guidelines and Recommendations for Musculoskeletal Ultrasound – Part I: Extraarticular Pathologies. Ultraschall in der Medizin. 2022.
3. Pan G, et al. Current status of dynamic musculoskeletal ultrasound for evaluation of extra-articular and intra-articular pathologies. 2024. Full text.

Content prepared by: Tomasz Poboży - orthopaedic surgeon.