Extensor carpi ulnaris subluxation

Case contributed by Amr Farouk
Diagnosis certain


Ulnar-sided wrist pain of several months' duration

Patient Data

Age: 25 years
Gender: Female

The extensor carpi ulnaris (ECU) tendon demonstrates medial palmar subluxation from its fibro-osseous tunnel. The tendon is subluxed into the pouch formed by stripping of the subsheath at its palmar attachment. Associated patchy area of bone marrow edema is seen involving the ulnar styloid process evoking a high STIR signal. Negative ulnar variance.

Annotated image

The extensor carpi ulnaris (ECU) tendon (red arrow) demonstrates medial palmar subluxation from its fibro-osseous tunnel (blue arrow).

Case Discussion

MR picture of extensor carpi ulnaris subluxation.

Subluxation or dislocation of the ECU tendon is associated with an injury to the ECU subsheath which may remain intact but stripped at its palmar/ulnar attachment, forming a false pouch into which the ECU tendon can sublux.

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