Question 1

Does ultrasound guidance make an injection more effective?

Accepted Answer

It reliably makes the injection more accurate, which is not the same thing. Placement is consistently more accurate than with landmark technique, but whether that improves pain and function differs by joint: there is no clear advantage for shoulder corticosteroid injection and modest gains in knee osteoarthritis. Ultrasound is most justified where accuracy decides whether the treatment can work.

Question 2

What is the difference between in-plane and out-of-plane technique?

Accepted Answer

In-plane means the needle advances along the long axis of the transducer within the beam, so the shaft and tip can be seen while the needle stays in the beam, which suits targets where precise tip control matters. Out-of-plane means the needle crosses the beam at right angles and shows only as a bright dot, which may be the shaft rather than the tip. Neither approach is universally preferable.

Question 3

Which transducer should be used?

Accepted Answer

The choice follows depth: a high-frequency linear transducer gives the best resolution for superficial targets such as the subacromial bursa, a tendon sheath or the common extensor origin. Deep targets such as the hip joint need a lower-frequency transducer with adequate penetration, commonly curvilinear but sometimes a lower-frequency linear probe, accepting lower resolution in exchange for depth.

Question 4

What is anisotropy and why does it matter?

Accepted Answer

Anisotropy is the apparent change in the echogenicity of a tendon when the beam is not perpendicular to its fibres, making a normal tendon look dark and potentially mimicking a tear. Adjusting the probe angle so the beam meets the fibres at right angles corrects it, and recognising it prevents a confident but wrong diagnosis.

Ultrasound-Guided Injection

Overview

Keep reading for free

Frequently asked questions

Related Topics