Wrist Ultrasound

Reference: Musculoskeletal Ultrasound: Anatomy and Technique, Springer 2008.

Setup

• High-frequency linear probe, ideally a hockey stick probe.
• Patient sits on the opposite side of the bed with their arm extended towards you.
• Scan dorsal, then volar. Always view tendons in both short axis and long axis.
• Compare with the other wrist.

Scan sequence

Dorsal wrist (De Quervain’s Tenosynovitis)

Position: Seated with the forearm in a neutral or semi-pronated position (“thumb up”).

Locate the Lister’s tubercle (the bony bump on the dorsal aspect of the distal radius, between Extensor Compartment 2 and 3. Place the probe in short axis.

Slide radially over Compartment 2 then Compartment 1 (abductor pollicis longus, extensor pollicis brevis).

Place the probe perpendicular to the APL and EPB tendons over the radial styloid. Scan both proximally and distally to trace the course of the tendons.

Abnormalities: Swollen and edematous APL and EPB tendons with increased fluid (hypoechoic) surrounding the tendons. Increased peritendinous blood flow visible on Color Doppler.

Volar wrist (Carpal Tunnel Syndrome)

Position: forearm supinated, wrist resting on the towel in mild extension.

Median nerve: sits just under the flexor retinaculum, above the flexor tendons, on the radial half of the wrist. Median nerve should have honeycomb appearance. Ask the patient to flex and extend the fingers: the nerve moves less than the tendons beneath it.

Carpal tunnel landmarks: proximal tunnel = scaphoid tubercle and pisiform. Distal tunnel = trapezium and hook of hamate.

Most useful measurement: median nerve cross-sectional area at the proximal tunnel, which should not exceed 10 mm squared.

Pitfalls

• Dark tendon from anisotropy mistaken for fluid or tenosynovitis.

Checklist

• Patient seated, wrist on towel, both wrists available
• Lister’s tubercle located
• Scan Compartment 1 tendons over the radial styloid
• Median nerve: shape, size, cross-sectional area, movement with finger flexion