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Distal intersection syndrome

Case contributed by Bahman Rasuli
Diagnosis almost certain

Presentation

Wrist pain.

Patient Data

Age: 30 years
Gender: Male
mri

Abnormal intrasubstance increased signal and surrounding edema is seen along the course of extensor pollicis longus (EPL) when crossing the extensor carpi radialis longus (ECRL) and extensor carpi radialis brevis (ECRB) tendons associated with ECRL and ECRB tenosynovitis.

A bipartite scaphoid is seen, presumably as a congenital variant. 

Bone marrow edema is noted at the triquetrum bone.

Case Discussion

The ECRB, ECRL and EPL tendons intersect distal to Lister’s tubercle and the radiocarpal joint. The tubercle acts as a pulley, changing the EPL tendon angle as it crosses superficially over the ECRL and ECRB tendons. This creates a mechanically disadvantageous arrangement, where the motion of the thumb and hand may cause friction between these tendons.

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