GAMEKEEPER THUMB - DIFFERENTIATION OF NONDISPLACED AND DISPLACED TEARS OF THE ULNAR COLLATERAL LIGAMENT WITH MR-IMAGING - WORK-IN-PROGRESS

Ulnar collateral ligament (UCL) injury of the first metacarpophalangea l joint (gamekeeper thumb) is common. If the UCL becomes displaced sup erficially to the adductor pollicis aponeurosis, surgical treatment ha s been advocated. Radiography cannot help differentiate between displa ced and nondisplaced tears. The authors investigated the use of magnet ic resonance (MR) imaging in the evaluation of UCL injury. Ten displac ed and six nondisplaced UCL tears were surgically created in 16 nonemb almed cadaveric specimens. Twelve unaltered specimens served as contro ls. Coronal MR images were obtained and interpreted by two observers. The MR images were compared with corresponding anatomic slices. MR ima ging depicted UCL displacement in all 10 specimens with displaced tear s. A displaced tear was interpreted in one control specimen. Nondispla ced tears were diagnosed in four control specimens. Although MR imagin g was only 67% specific for all tears, it was 100% sensitive and 94% s pecific for depicting UCL displacement and, therefore, may be useful f or evaluating gamekeeper thumb.