title: Porotic paradox: distribution of cortical bone pore sizes at nano- and micro-levels in healthy vs. fragile human bone.
abstract: Bone is a remarkable biological nanocomposite material showing peculiar hierarchical organization from smaller (nano, micro) to larger (macro) length scales. Increased material porosity is considered as the main feature of fragile bone at larger length-scales. However, there is a shortage of quantitative information on bone porosity at smaller length-scales, as well as on the distribution of pore sizes in healthy vs. fragile bone. Therefore, here we investigated how healthy and fragile bones differ in pore volume and pore size distribution patterns, considering a wide range of mostly neglected pore sizes from nano to micron-length scales (7.5 to 15000 nm). Cortical bone specimens from four young healthy women (age: 35 ± 6 years) and five women with bone fracture (age: 82 ± 5 years) were analyzed by mercury porosimetry. Our findings showed that, surprisingly, fragile bone demonstrated lower pore volume at the measured scales. Furtnermore, pore size distribution showed differential patterns between healthy and fragile bones, where healthy bone showed especially high proportion of pores between 200 and 15000 nm. Therefore, although fragile bones are known for increased porosity at macroscopic level and level of tens or hundreds of microns as firmly established in the literature, our study with a unique assessment range of nano-to micron-sized pores reveal that osteoporosis does not imply increased porosity at all length scales. Our thorough assessment of bone porosity reveals a specific distribution of porosities at smaller length-scales and contributes to proper understanding of bone structure which is important for designing new biomimetic bone substitute materials.
authors.affiliation: Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, 4/2 Dr Subotica, Belgrade, 11000, Serbia.
authors.forename: Petar
authors.initials: P
authors.lastname: Milovanovic
authors.affiliation: Department of Catalysis and Chemical Engineering, Institute of Chemistry, Technology and Metallurgy, University of Belgrade, 12 Njegoseva, Belgrade, 11000, Serbia.
authors.forename: Zorica
authors.initials: Z
authors.lastname: Vukovic
authors.affiliation: Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, 4/2 Dr Subotica, Belgrade, 11000, Serbia.
authors.forename: Djordje
authors.initials: D
authors.lastname: Antonijevic
authors.affiliation: Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, 4/2 Dr Subotica, Belgrade, 11000, Serbia.
authors.forename: Danijela
authors.initials: D
authors.lastname: Djonic
authors.affiliation: Institute of Forensic Medicine, Faculty of Medicine, University of Belgrade, 31a Deligradska, Belgrade, 11000, Serbia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Zivkovic
authors.affiliation: Institute of Forensic Medicine, Faculty of Medicine, University of Belgrade, 31a Deligradska, Belgrade, 11000, Serbia.
authors.forename: Slobodan
authors.initials: S
authors.lastname: Nikolic
authors.affiliation: Laboratory for Anthropology, Institute of Anatomy, Faculty of Medicine, University of Belgrade, 4/2 Dr Subotica, Belgrade, 11000, Serbia. marijadjuric5@gmail.com.
authors.forename: Marija
authors.initials: M
authors.lastname: Djuric
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000071538:Cortical Bone / Q000000981:diagnostic imaging / Q000502:physiology* / Q000648:ultrastructure*; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging / Q000502:physiology / Q000648:ultrastructure; D006620:Hip Fractures / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D053761:Nanocomposites / Q000648:ultrastructure; D015663:Osteoporosis, Postmenopausal / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D016062:Porosity; D055114:X-Ray Microtomography