Modeling of fractured clavicles and reconstruction plates using CAD, finite element analysis and real musculoskeletal forces input

This study focuses on the treatment options for clavicle fractures, more specifically the cases with a need for internal fixation: non-unions and some complex fractures. Enhancing the understanding of the loading of the bone and fixation device enables treatment options to be improved. The aim of the study was to develop a method for the realistic simulation of stresses and displacements in the bone and fixation device and to use this method to make comparisons between a conventional reconstruction plate and a customized plate, designed from patient-specific computed tomography (CT) data. In an earlier study, a finite element (FE) mesh of the clavicle geometry was created from CT data, subjected to muscle forces and other boundary conditions from a multibody musculoskeletal model and imported into the FE solver. In this study, a solid 3D model of the same clavicle geometry was created and the mesh was replaced by the solid model to make the FE-model more suitable for the comparison of different plates. An LCP Reco-Plate 3.5 straight, 6 holes (by Synthes) was compared with a customized plate which was designed to follow the anatomy of the bone. The LCP-Reco plate has tapered reconstruction segments throughout the plate to allow for the plate reshaping during surgery. The customized plate was designed without such segments and with a lower width than the LCP plate. The two different plates showed stresses and displacements of similar magnitudes. The customized plate had a more even stress distribution while the LCP plate had higher stress concentrations in the middle of the plate and on the edges of the tapered reconstruction segments. To the authors' best knowledge, this is the first FE model of a clavicle bone with plate and it may, upon further development, serve as a useful instrument for improved clavicle fixation.