MR Imaging of the Thumb Carpometacarpal Joint.

The thumb carpometacarpal (CMC) joint is the most critical of the 4 articulations comprising the basal joints of the thumb. Peculiar anatomy, inherent instability, and function predispose this joint to repetitive microtrauma and eventual osteoarthritis (OA), often resulting in debilitating disease. Clinical examination and radiographs are usually sufficient in evaluating this joint while MR imaging may play an important role in the evaluation of more complex pathologies and postoperative complications. This article summarizes normal MR imaging anatomy as well as degenerative, traumatic, and various pathologic and postoperative findings of the thumb CMC joint.