The role of US in the evaluation of clinically suspected ulnar collateral ligament injuries of the thumb: spectrum of findings and differential diagnosis.

Injury to the ulnar collateral ligament (UCL) complex of the thumb is a common traumatic lesion that requires prompt imaging evaluation for adequate treatment. In this article, we review the role of ultrasound in diagnosis and illustrate the spectrum of both static and dynamic findings related to the UCL injuries. We also describe a number of alternative diagnoses in the vicinity of the first metacarpophalangeal joint that may present clinically as pseudoligamentous lesions in a trauma setting.