Presentation
Chronic wrist pain at dorsal aspect.
Patient Data
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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.
Fusiform thickening of extensor carpi ulnaris tendon at the level of ulna styloid and carpal proximal row bones due to tendinosis.
Case Discussion
The ECRB, ECRL, and EPL tendons intersect distal to Lister’s tubercle and radiocarpal joint. The tubercle acts as a pulley, changing the EPL tendon angle when 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.