Ulnar collateral ligament: differentiation of displaced and nondisplaced tears with US.

PURPOSE: To determine the usefulness of ultrasound (US) in the differentiation of displaced and nondisplaced tears of the ulnar collateral ligament (UCL). MATERIALS AND METHODS: A 7.5-10-MHz linear-array transducer was used to examine 69 patients in whom a UCL tear was suspected, 43 of whom also underwent surgery. The US findings were compared with those obtained at surgery. RESULTS: Results of US corresponded to results of surgery in 37 of 43 patients. Findings were false-positive in six patients. Twenty-six patients were treated conservatively with thumb casts. These patients showed stability and free range of motion at the first metacarpophalangeal joint at clinical follow-up (9-13 months). CONCLUSION: Sonography is useful for evaluating nondisplaced and retracted tears of the UCL and determining the need for surgery.