An important feature of humeral orthopedic finite element (FE) models is the trabecular stiffness relationship. These relationships depend on the anatomic site from which they are derived; but have not been developed for the humerus. As a consequence, humeral FE modeling relies on relationships for other anatomic sites. The variation in humeral FE outcomes due to the trabecular stiffness relationship is assessed. Stemless arthroplasty FE models were constructed from CT scans of eight humeri. Models were loaded corresponding to 45 deg and 75 deg abduction. Each bone was modeled five times with the only variable being the trabecular stiffness relationship: four derived from different anatomic-sites and one pooled across sites. The FE outcome measures assessed were implant-bone contact percentage, von Mises of the change in stress, and bone response potential. The variance attributed to the selection of the trabecular stiffness relationship was quantified as the standard deviation existing between models of different trabecular stiffness. Overall, variability due to changing the trabecular stiffness relationship was low for all humeral FE outcome measures assessed. The variability was highest within the stress and bone formation potential outcome measures of the trabecular region. Variability only exceeded 10% in the trabecular stress change within two of the eight slices evaluated. In conclusion, the low variations attributable to the selection of a trabecular stiffness relationship based on anatomic-site suggest that FE models constructed for shoulder arthroplasty can utilize an inhomogeneous site-pooled trabecular relationship without inducing marked variability in the assessed outcome measures.
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http://dx.doi.org/10.1115/1.4042172 | DOI Listing |
Bone
January 2025
ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.
Nonlinear homogenised finite element (hFE) models can accurately predict stiffness and strength of ultra-distal sections of the radius and tibia using in vivo HR-pQCT images. Recent findings showed good stiffness prediction at these distal sections but a limited ability to reproduce experimental strain localisation. The coarseness of voxel-based meshes reduces the computational effort at the cost of heavily simplifying the underlying geometry of the cortex, the gradient of material properties, and the resulting strain distribution.
View Article and Find Full Text PDFCalcif Tissue Int
January 2025
Department of Bioengineering, Temple University, 1947 N. 12th St, Philadelphia, PA, 19122, USA.
Bone mechanical function is determined by multiple factors, some of which are still being elucidated. Here, we present a multivariate analysis of the role of bone tissue composition in the proximal femur stiffness of cadaver bones (n = 12, age 44-93). Stiffness was assessed by testing under loading conditions simulating a sideways fall onto the hip.
View Article and Find Full Text PDFJ Mech Behav Biomed Mater
January 2025
Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA; Center for Multiscale and Translational Mechanobiology, Boston University, Boston, MA 02215, USA; Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA.
Despite the broad agreement that bone stiffness is heavily dependent on the underlying bone density, there is no consensus on a unified relationship that applies to both cancellous and cortical compartments. Bone from the two compartments is generally assessed separately, and few mechanical test data are available for samples from the transitional regions between them. In this study, we present a data-driven framework integrating experimental testing and numerical modeling of the human lumbar vertebra through an energy balance criterion, to develop a unified density-modulus relationship across the entire vertebral body, without the necessity of differentiation between trabecular and cortical regions.
View Article and Find Full Text PDFInvest Ophthalmol Vis Sci
January 2025
Department of Ophthalmology, Duke Eye Center, Duke University, Durham, North Carolina, United States.
Purpose: To study the roles of tubulin acetylation and cyclic mechanical stretch (CMS) in trabecular meshwork (TM) cells and their impact on outflow pathway physiology and pathology.
Methods: Primary TM cell cultures were subjected to CMS (8% elongation, 24 hours), and acetylated α-tubulin at lysine 40 (Ac-TUBA4) was assessed by western blotting and immunofluorescence. Enzymes regulating tubulin acetylation were identified via siRNA-mediated knockdowns of ATAT1, HDAC6, and SIRT2.
Bone
December 2024
Marrow Adiposity and Bone Lab, MABLab-ULR4490, Univ. Littoral Côte d'Opale F-62200 Boulogne-sur-Mer, Univ. Lille F-59000 Lille, CHU Lille, F-59000 Lille, France. Electronic address:
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