Ultrasound of displaced ulnar collateral ligament tears of the thumb: the Stener lesion revisited.

PURPOSE: To retrospectively characterize the ultrasound appearance of displaced ulnar collateral ligament (UCL) tears that are proven at surgery, and then determine the accuracy of the resulting ultrasound criteria in differentiating displaced from non-displaced UCL tears.
MATERIALS AND METHODS: After institutional review board approval, 26 patients were identified from the radiology information system over a 10-year period that had ultrasound evaluation of the thumb and surgically proven UCL tear. Retrospective review of the displaced full-thickness tears was carried out to characterize displaced tears and to establish ultrasound criteria for such tears. A repeat retrospective review 4 months later of all UCL tears applied the criteria to determine accuracy of ultrasound in the diagnosis of displaced full-thickness UCL tear.
RESULTS: The 26 subjects consisted of 17 displaced full-thickness UCL tears, seven non-displaced full-thickness tears, and two partial-thickness tears at surgery. Retrospective ultrasound review of displaced full-thickness tears identified two criteria present in all cases: non-visualization of the UCL ligament and presence of a heterogeneous mass-like area proximal to the first metacarpophalangeal joint. Applying these criteria at the second retrospective review resulted in 100 % sensitivity, specificity, positive predictive value, negative predictive value, and accuracy.
CONCLUSIONS: The ultrasound findings of absent UCL fibers and presence of a heterogeneous mass-like abnormality proximal to the first metacarpophalangeal joint achieved 100 % accuracy in differentiating displaced from non-displaced full-thickness UCL tear of the thumb. Displaced full-thickness UCL tears most commonly were located proximal to the adductor aponeurosis.