gms | German Medical Science

Objectives/Interrogation: In Kienböck's disease, conservative surgical techniques aim to decompress the lunate. Many osteotomies are proposed. most involve the radius, the ulna or the capitate. Seven procedures were compared in terms of unloading by the authors.

Methods: To validate the comparison, a 3D finite elements model was built. The model was obtained from the segmentation of CT scans of an healthy wrist and imported into a finite element calculation software (Abaqus-Dassault systems). Authors add the ligaments, the cartilage shell and the TFCC with physical properties according to the literature.

The radius axial shortening (AS), lateral closing (LC), medial closing (MC), the Camembert osteotomy without (C) and with Sennwald osteotomy (CS), the capitate shortening without (Ca) and with the hamate (CaH) shortening were compared.

Results and Conclusions: The different osteotomies were simulated, and the contact forces and stresses were recorded. In the anatomical model, the loads towards the forearm are brought by the scaphoid at 56%, the lunate at 30%, the triquetrum at 14%.

• In AS they are respectively 41%, 29%, 28%;
• in LC 50%, 45% and 5%;
• in the MC 20%, 61%, 18%;
• in the Ca 79%, 11%, 10%;
• in the CaH 70%, 5%, 25%;
• in C 53%, 29%, 18%;
• in the CS 80%, 0%, 20%.

In this model, The osteotomies that best discharge the lunate are the CaH osteotomy and the CS osteotomy. Compared to initial model, the CaH osteotomy overloads ulna, whose contact force increases from 14% to 25%. In the CS, most of the stresses are supported by the scaphoid, the ulna overload is minimal and the lunate discharge is complete. The Camembert-Sennwald osteotomy seems, in this model, to best unload the lunate, without overloading the ulna.