What is the ECU tendon?
The ECU tendon is the extensor carpi ulnaris tendon. It is one of the many extensor tendons on the back of the wrist which extends the wrist, thumb or fingers.
The ECU tendon is along the little finger side of the wrist. We doctors call it the “ulnar” side of the wrist. It is a powerful wrist extensor – it moves the wrist backwards.
What is the ECU Subsheath?
The extensor tendons on the back of the wrist are held down to the bones by a series of fibrous tunnels or sheaths.
The ECU subsheath holds the ECU onto the groove of the distal ulnar bone.
What is an ECU Subsheath Tear or Injury?
The ECU subsheath can tear and the ECU tendon may pop out of place (sublux or dislocate out of the groove) causing a snapping sensation and/or pain.
This injury can present in weight lifters, tennis players and golfers amongst other sports.
What Are the Symptoms?
- Pain on the ulnar side of the wrist.
- Pain on pronation or supination of the wrist.
- Pain on wrist extension.
- Popping or snapping of the tendon on the wrist.
What Investigation to Do?
An MRI scan is helpful to assess the ECU tendon as well as to see if it is resting in the right position. This MRI showed that the tendon was subluxed out of the ulnar styloid groove. This indicated a subsheath injury.
What are the Possible Treatments?
- Rest the wrist joint by casting it in pronation.
- Oral anti-inflammatory medications.
- Surgery – Subsheath repair.