[Experimental carpal displacement induced by ligamental lesions]

Ligamentous lesions were created experimentally in 40 fresh cadaver wrists. The precise localization of traumatic rupture of the ligaments and the subsequent carpal imbalance were defined by the comparison between the experimental results and the clinical displacements. The displacements may be permanent, sequential or induced by external forces. Lesions of capsular ligaments cause the displacement. There are 3 functional units; the distal scaphoid complex; the palmar ligaments which form a "belt", consisting of the lateral external ligament, the radiocarpal ligaments an the radiate ligament; the medial ligaments, which also form a "belt" consisting of the palmar triquetral ligaments on each side of the triquetrum. The sprains are caused by a lesion of a functional unit. The lateral sprain is characterized by a lesion of the distal scaphoid complex. The scaphoid moves into a horizontal position, causing a dorsal deviation of the lunate and a scapholunate diastasis. The central sprain is induced by a rupture of the palmar "belt", causing an anteroposterior radiocarpal or mediocarpal drawer movement. The medial sprain is induced by the rupture, of different extents, of the medial ligaments. On examination, there is either a click or a palmar deviation of the lunate, sometimes with a lunotriquetral diastasis. The dislocations of the wrist are caused by lesion of several ligamentous units.