Characteristics of the Flexor Carpi Radialis Brevis Tendon on Magnetic Resonance Imaging and its Use in Basal Joint Arthroplasty.

We report the incidental discovery of a flexor carpi radialis brevis tendon, a rare anatomical variant identified during a surgical procedure. Magnetic resonance imaging of the contralateral side helped to delineate the anatomy of the flexor carpi radialis tendon and to differentiate the flexor carpi radialis brevis tendon from it. We describe the use of this rare tendon in ligament reconstruction of the basal joint of the thumb.