title: A modelling approach demonstrating micromechanical changes in the tibial cemented interface due to in vivo service.
abstract: Post-operative changes in trabecular bone morphology at the cement-bone interface can vary depending on time in service. This study aims to investigate how micromotion and bone strains change at the tibial bone-cement interface before and after cementation. This work discusses whether the morphology of the post-mortem interface can be explained by studying changes in these mechanical quantities. Three post-mortem cement-bone interface specimens showing varying levels of bone resorption (minimal, extensive and intermediate) were selected for this study Using image segmentation techniques, masks of the post-mortem bone were dilated to fill up the mould spaces in the cement to obtain the immediately post-operative situation. Finite element (FE) models of the post-mortem and post-operative situation were created from these segmentation masks. Subsequent removal of the cement layer resulted in the pre-operative situation. FE micromotion and bone strains were analyzed for the interdigitated trabecular bone. For all specimens micromotion increased from the post-operative to the post-mortem models (distally, in specimen 1: 0.1 to 0.5µm; specimen 2: 0.2 to 0.8µm; specimen 3: 0.27 to 1.62µm). Similarly bone strains were shown to increase from post-operative to post-mortem (distally, in specimen 1: -185 to -389µε; specimen 2: -170 to -824µε; specimen 3: -216 to -1024µε). Post-mortem interdigitated bone was found to be strain shielded in comparison with supporting bone indicating that failure of bone would occur distal to the interface. These results indicate that stress shielding of interdigitated trabeculae is a plausible explanation for resorption patterns observed in post-mortem specimens.
authors.affiliation: Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands. Electronic address: priyanka.srinivasan@radboudumc.nl.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Srinivasan
authors.affiliation: Department of Orthopedic Surgery, State University of New York, Upstate Medical University, Syracuse, NY, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Miller
authors.affiliation: Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands; University of Twente, Laboratory for Biomechanical Engineering, Faculty of Engineering Technology, Enschede, The Netherlands.
authors.forename: Nico
authors.initials: N
authors.lastname: Verdonschot
authors.affiliation: Department of Orthopedic Surgery, State University of New York, Upstate Medical University, Syracuse, NY, USA.
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Mann
authors.affiliation: Radboud University Medical Center, Radboud Institute for Health Sciences, Nijmegen, The Netherlands.
authors.forename: Dennis
authors.initials: D
authors.lastname: Janssen
mesh_terms: D000369:Aged, 80 and over; D001843:Bone Cements; D001862:Bone Resorption; D002484:Cementation; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D009068:Movement / Q000502:physiology; D013314:Stress, Mechanical; D013977:Tibia / Q000502:physiology*
chemical_list: D001843:Bone Cements
keywords: Bone strain; Bone–cement interface; Finite element analysis; Micromotion; Tibial loosening