Oral Presentation ANZBMS-MEPSA-ANZORS 2022

Variance in Estimated Strength Along the Femoral Neck and Radius is Accounted for Differences in Macro- and Micro-architecture, not Bone Mass (#89)

Ali Ghasem-Zadeh 1 , Naghmeh Firouzi 2 , Olga Panagiotopoulou 3 , Phil Salmon 4 , Narelle McGregor 5 , Rita Hardiman 6 , Natalie Sims 5 , Ego Seeman 1
  1. Departments of Endocrinology and Medicine , Austin Health, the University of Melbourne, Heidelberg, VIC, Australia
  2. Preclinical Laboratory, Department of Medicine , Tehran University of Medical Sciences, Tehran, Iran
  3. Monash Biomedicine Discovery Institute, Department of Anatomy & Developmental Biology, Monash University, Melbourne, VIC, Australia
  4. Bruker Micro-CT, Kontich, Belgium
  5. Bone Cell Biology & Disease Unit, St. , Vincent's Institute of Medical Research, Melbourne, VIC, Australia
  6. Melbourne Dental School, Faculty of Medicine, Dentistry and Health Sciences, , The University of Melbourne, Melbourne, VIC, Australia

Introduction    Resistance to fracture is achieved by modelling and remodelling adding bone to, or removing bone from, its periosteal (external) and three (endocortical, intracortical, trabecular) components of its endosteal (internal) surfaces.  These cellular events modify the spatial distribution and mineral content of the volume of bone without necessarily altering its mass.  For example, similar amounts of bone are used to assemble adjacent cross sections differing in size, shape and microarchitecture along a tubular bone.1,2 As these studies were confined to regions only ~36 mm in length, we hypothesized that, if this observation is confirmed in whole post-mortem specimens, the variance within a cross-section, and from cross-section to cross-section along a bone will be accounted for by focal differences in macro- and micro-architecture, not mass.

Methods          We quantified macro-structure of the cross-sections of 5 radii and 5 femora from human post-mortem specimens using CT-Scan (300 microns), and micro-structure of the cross-sections of the distal and proximal metaphyseal-diaphyseal regions (1/3 of bone length) of 18 radii and 5 femora using HR-pQCT (82 micron).  Bone cross sectional area, moment of inertia and cortical thickness were measured using Bone J and 3Matic software for CT images. Finite element analysis (FEA) was used to estimate bone strength.

Results            Bone mass was constant along diaphyseal regions of radii, femoral neck and distal femur (figure).  Along the metaphyseal regions, the constant mass was fashioned with a large void volume and high surface area/matrix volume forming mainly trabecular bone.  At the mid-diaphyseal regions the same mass was fashioned with small intracortical and medullary void volumes and low surface area/matrix volume forming cortical bone.  Preliminary FEA showed a reduction in strains in areas with greater cortical thickness and moment of inertia. 

Conclusion      Maintaining optimal focal strain is achieved by diversity in structure more than mass. 62985f10627a8-ANZBMS+Abstract+-Ali+Ghasem-Zadeh.JPG

  1. 1.Ghasem-Zadeh A, et al. Bone. 2017 Aug; 101:206-213. PMID: 28502884 2.Zebaze RM, et al. J Bone Miner Res. 2007 Jul;1055-61. PMID: 17501625.