ecu

Symptoms

Sudden onset of pain without history of trauma

- ulnar aspect of the wrist

- particularly associated with repetitive ulnar deviation

Signs

Swelling over the ECU or FCU tendon sheaths 

- occasional crepitation on range of motion

X-ray 

May show calcific deposits within the tendon sheath

Anatomy

6th compartment

- fibro-osseous tunnel overlying 1.5 cm to 2.0 cm of distal ulna

- held tight by the extensor carpi ulnaris tendon sheath

- the extensor retinaculum passes around the ulna to insert on the palmar aspect of the carpus

- extensor retinaculum is a separate structure from the ECU tendon sheath

Mechanism

Forced supination, palmar flexion, and ulnar deviation