Carpal boss in chronic wrist pain and its association with partial osseous coalition and osteoarthritis - A case report with focus on MRI findings

The carpal boss is a bony prominence at the dorsal aspect of the 2(nd) and/or 3(rd) carpometacarpal joint, which has been linked to various etiologies, including trauma, os styloideum, osteophyte formation, and partial osseous coalition. It may result in symptoms through secondary degeneration, ganglion formation, bursitis, or extensor tendon abnormalities by altered biomechanics of wrist motion. We present a case of symptomatic carpal boss with the finding of a partial osseous coalition at the 2(nd) carpometacarpal (metacarpal–trapezoid) joint and highlight the magnetic resonance imaging (MRI) findings of carpal boss impingement and secondary osteoarthritis. To the best of our knowledge, there is no report in the literature describing the imaging findings of partial osseous coalition and degenerative osteoarthritis in relation to carpal boss.