Difference in Carpal Alignment between Scapholunate Dissociation and Kienbock Disease: A Retrospective Study

Introduction  Scapholunate dissociation is the most frequent type of wrist instability and, if untreated, can lead to wrist osteoarthritis, known as scapholunate advanced collapse. Kienbock disease can also lead to wrist osteoarthritis. Both involve carpal instability; however, the possibility of completely different mechanisms underlying each ligamentous state and carpal malalignment must be considered. Materials and Methods  We retrospectively reviewed 17 patients with scapholunate dissociation and 14 patients with Kienbock disease. All arthroscopic findings for scapholunate dissociation were classified as Geissler grade 4. All cases of Kienbock disease were treated by lunate resection and vascularized pisiform transfer without interosseous ligament reconstruction. Carpal alignments were evaluated from pre- and postoperative radiographs. Results  Scapholunate dissociation showed greater lunate dorsiflexion and more dorsal locations of the scaphoid and capitate compared with Kienbock disease, but preoperative scaphoid flexion was similar in both groups. Eleven of 17 cases of scapholunate dissociation and no cases of Kienbock disease showed dorsal subluxation of the scaphoid preoperatively. Postoperative radiographs revealed no progression of carpal collapse in either groups. Conclusion  This study revealed the sacrifice of the scapholunate/lunotriquetral interosseous ligament do not incur static scapholunate dissociation, and that the secondary stabilizers may preserve carpal alignment.