End-constraint is needed when performing tensile and compressive testing of cancellous bone so that frictional and structural end-effects are minimized and the mechanical properties are not underestimated. Since many end-constrained testing techniques are limited to certain sites and species by the large specimen sizes required, reductions in overall specimen length would be advantageous. The following study examines the effect of specimen gauge length and aspect ratio on the elastic tensile testing of cancellous bone from the bovine femoral condyle. Three different nominal gauge lengths (10, 16, 22 mm) were examined at two different diameters (5.1, 10.7 mm) which bound the range typically used for cancellous bone testing. No effect of gauge length or aspect ratio was observed, but evidence of a diameter effect was noted. Three-dimensional finite element method (FEM) models confirmed the experimental observations and demonstrated that an overestimation of modulus begins to occur for specimens shorter than 10 mm.
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http://dx.doi.org/10.1016/j.jmbbm.2009.02.001 | DOI Listing |
J Endocrinol
January 2025
U Iwaniec, Skeletal Biology Laboratory, Oregon State University, Corvallis, United States.
Leptin increases focal inflammation and osteolysis induced by polyethylene particles in leptin-deficient ob/ob mice suggesting the adipokine, an important immune modulator, contributes to orthopedic implant failure. Focal inflammation leads to bone loss at distant skeletal sites, and it is plausible that leptin also contributes to this response. We tested this possibility in 6-week-old female ob/ob mice (6-8/group) by evaluating bone architecture, turnover, and gene expression 12 days following surgical placement of polyethylene particles over calvaria.
View Article and Find Full Text PDFJ Dent Sci
January 2025
Department of Physical Therapy and Assistive Technology, National Yang Ming Chiao Tung University, Taipei, Taiwan.
Background/purpose: The use of finite element (FE) analysis in implant biomechanics offers many advantages over other approaches in simulating the complexity of clinical situations. The aim of this study was to perform an optimization analysis of dental implants with different thread designs in three types of bone quality.
Materials And Methods: The three-dimensional FE model of a mandibular bone block with a screw-shaped dental implant and superstructure was simulated.
J Am Podiatr Med Assoc
January 2025
*Department of Orthopedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA.
Background: Ankle fractures continue to increase in incidence and severity in an older, more challenging geriatric population. Medial malleolus fixation with partially threaded cancellous 4.0-mm screws, a common fixation method, has been shown to fail due to pullout strength.
View Article and Find Full Text PDFComput Methods Biomech Biomed Engin
January 2025
Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China.
The most common type of proximal humerus fracture is surgical neck fracture. The purpose of this paper is to study the mechanical mechanism and the effect of bone degeneration on humeral surgical neck fractures. The right humerus finite element models were established based on CT computed tomography.
View Article and Find Full Text PDFMol Cell Endocrinol
January 2025
Shanghai University of Sport, School of Health and Exercise, Shanghai 200438, China. Electronic address:
To clarify the roles and mechanisms of adipokine chemerin in exercise-induced bone improvements in type 2 diabetes mellitus (DM) mice and mice fed on high fat diet (HFD). DM mice were established by HFD+streptozotocin injection, exogenous chemerin was supplemented prior to running, and found that exogenous chemerin reversed 6-week exercise-induced improvements in cancellous bone parameters in DM mice. While adipose-specific chemerin knockout improved microstructure and mass of cancellous bone in HFD mice and further increased exercise-induced bone improvements, accompanied with promoted osteogenesis and inhibited osteoclasis represented as the changes of RANKL, M-CSF, Runx2, Osterix, OPG, ALP and CTSK.
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