Hi, my name is Brennan Boettcher from Mayo Clinic, and this is an ultrasound consult on trigger finger. The patient in this case was found to have triggering of the right ring finger. To scan the volar aspect of the finger, you can use a high-frequency linear transducer or a small footprint high-frequency linear transducer. Here we are scanning the volar aspect of the normal finger at the level of the A1 pulley. Notice we have the FDS tendon sitting superficial to the FTP tendon, which overlies the palmar plate and the metacarpal. The radial neurovascular structures and the ulnar neurovascular structures are present on either side of the flexor tendons and the A1 pulley. The A1 pulley, which sits superficial and runs on either side of the flexor tendons, displays edge shadowing. This is an artifact which happens when the ultrasound transducer and the beam hits a curved surface. Here we are scanning the volar aspect of the hand and finger at the level of the superficial transverse metacarpal ligament. Note the FDS tendon sits superficial to the FTP tendon. There's free anechoic fluid, which sits within the flexor tendon sheath. The neurovascular structures are once again noted on either side of the flexor tendons, and the flexor tendons for the adjacent fingers can oftentimes be seen with a larger footprint transducer. Here we glide distal starting in the palm on the volar aspect of the hand and finger. We note the FDS tendon sitting superficial to the FTP tendon. As we pass through the palm, we once again see the anechoic fluid, which was noted on the prior slide within the tendon sheath. At the level of the distal metacarpal, we see the FDS tendon over the FTP tendon and the A1 pulley overlying the top. Once again, we see edge shadowing artifact on either side of the tendon. This is a normal artifact that is seen both in normal and abnormal tendons, although in patients who have trigger finger, we tend to see enlargement of that edge shadowing relative to the normal edge shadowing visualized in a more normal tendon as is seen in either side of this image. At the level of the A1 pulley, we once again see the FDS tendon over the FTP tendon. Within the FDS tendon, we see hypoecogenicity and enlargement. This is oftentimes seen as a nodule within the flexor tendons in patients with trigger finger. The A1 pulley is measured here to be 0.12 centimeters in thickness. This is an abnormal measurement and indicative of a patient with trigger finger. Here I will rotate my transducer into a sagittal plane to be long on the flexor tendons. The FDS tendon sits superficial to the FTP tendon and the A1 pulley is normally a thin structure overlying the MCP joint. In this patient, the structure is thickened and the edges are slightly blurred, which is oftentimes seen in patients with trigger finger. The patient will then be asked to actively and passively flex the finger in question. With this, the flexor tendons are visualized dynamically, looking for disconjugate motion between the FDS and FTP tendons or bunching, both of which are seen on this video. Additional findings include triggering, which will be shown in the companion case on the next slide. In this companion case, the finger triggers. The nodule initially bunches up underneath the A1 pulley as was seen on the prior image. However, after bunching up, the tendon slides quickly beneath the A1 pulley, recreating the patient's typical triggering symptoms.

3rd Edition, CASE 20

3rd Edition

Hand

ultrasound evaluation

trigger finger

high-frequency transducer

FDS tendon

A1 pulley