A kinematic study of luno-triquetral dissociations.

An analysis of carpal motion after sectioning the ligamentous support of the luno-triquetral joints was done by use of stereoradiographic methods. The ligaments were sectioned in two stages. In stage I, a complete sectioning of both the dorsal and palmar luno-triquetral ligaments and the interosseous membrane was done. Stage II consisted of further sectioning of both the dorsal radio-triquetral and dorsal scapho-triquetral ligaments. After both stage I and stage II ligament sectioning, all of the intercarpal joints exhibited altered kinematics. The changes were especially marked at the luno-triquetral joint where motion was increased in all planes of wrist motion. The essential lesion in producing a static palmar flexed intercalated segment instability was division of the dorsal radio-triquetral and dorsal scapho-triquetral ligaments in association with the luno-triquetral ligaments and interosseous membrane sectioning.