Fig. 4

Male patient 36 years old, complaining of right thumb pain, swelling and limitation of movement following finger trauma. Axial T2WI (a, b) of the right thumb revealed fluid signal surrounding the flexor pollicis longus tendon (curved yellow arrow) and edematous changes of the thenar muscles (curved white arrow) and the metacarpophalangeal region. Coronal STIR (c) and coronal proton density (d) weighted imaging of the right thumb at the level of the metacarpophalangeal (MCP) joint showed no definite proximal attachment of the medial collateral ligament (straight yellow arrow) with surrounding hyperintense fluid signal and mild metacarpophalangeal joint effusion (straight white arrow). Diagnosis was right thumb ulnar collateral ligament tear at the level of the metacarpophalangeal joint with tenosynovitis of the flexor pollicis longus and mild metacarpophalangeal joint effusion