The Anatomic, Constraint and Material Properties of the Scapholunate Interosseous Ligament: A Preliminary Study

Abstract

The scapholunate interosseous ligament normally connects the scaphoid and lunate carpal bones by spanning the proximal, dorsal and palmar margins of the scapholunate joint. It has been felt to be a critical structure for maintaining structural integrity within the proximal carpal row, and thus important in maintaining normal carpal mechanics.1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21 Complete disruption of the scapholunate ligament has been associated with a clinical condition of instability termed dorsal intercalated segmental instability (DISI), which is felt to be a precursor of advancing degenerative disease,11 but there is no clear concensus regarding the effects of partial scapholunate ligament disruption. In the laboratory, efforts have been made to study the kinematic influences of this ligament, however conflicting results have been published.2,18 Previous anatomic investigations have revealed the complexity of the interface between the scapholunate and radioscapholunate ligaments, but specific investigations of the scapholunate ligament anatomy have not been published.3 Additionally, material property studies have been carried out on the scapholunate ligament in two published studies.13,16 In both studies, distraction to failure was applied to the entire ligament, which may not represent physiologic failure. In order to obtain a better understanding of the role of the scapholunate ligament on the mechanics of the wrist and the relative contributions of the anatomic subregions of the ligament, we designed an investigation to evaluate the detailed gross and histologic anatomy and mechanical properties of the subregions of the scapholunate interosseous ligament.