title: Human iliac crest cancellous bone elastic modulus and hardness differ with bone formation rate per bone surface but not by existence of prevalent vertebral fracture.
abstract: The goals of this study were to measure tissue-level elastic moduli and hardness of human cancellous bone using nanoindentation, and determine the relationship between nanoindentation results and previously measured bone histomorphometric variables and bone mineralization. Forty iliac crest biopsies were used in this study, which were collected from Caucasian females with vertebral fracture or from a normal healthy female Caucasian population. They were also categorized into two groups according to high or low bone formation rate per bone surface (BFR/BS). Thirty-two sites were randomly selected on each specimen for nanoindentation with a Berkovich diamond indenter. Two sets of elastic moduli and hardness were calculated using the continuous stiffness measurement method and the Oliver-Pharr method, respectively. Relationships between nanoindentation results and donor age, bone mineralization, and histomorphometric variables were examined. No difference in elastic moduli or hardness was observed between the normal and fracture groups. Significantly lower elastic moduli were observed in the high BFR/BS group. The elastic moduli and hardness measurements were not significantly correlated with the bone mineralization measured independently in a previous study. Linear correlation between elastic modulus and hardness calculated using the Oliver-Pharr method was not different between the normal and fracture groups or between the high and low BFR/BS groups. Nanoindentation hardness was a very good predictor of bone tissue elastic modulus for both normal and osteoporotic bone tissues. Osteoporosis may not change the relationship between bone tissue elastic modulus, bone hardness, and bone mineralization.
authors: Lawrence J. Ellison Musculoskeletal Research Center, University of California Davis Medical Center, Room 2000, Research Facility I, 4635 Second Avenue, Sacramento, California 95817, USA. xswang@ucdavis.edu
authors: Xiang
authors: X
authors: Wang
authors: D
authors: D
authors: Sudhaker Rao
authors: Leonardo
authors: L
authors: Ajdelsztajn
authors: Traci E
authors: TE
authors: Ciarelli
authors: Enrique J
authors: EJ
authors: Lavernia
authors: David P
authors: DP
authors: Fyhrie
mesh_terms: D001706:Biopsy; D001842:Bone and Bones / Q000737:chemistry / Q000378:metabolism; D002113:Calcification, Physiologic / Q000502:physiology; D019245:Compressive Strength; D004548:Elasticity; D005260:Female; D006244:Hardness; D006245:Hardness Tests; D006801:Humans; D007085:Ilium / Q000033:anatomy & histology / Q000378:metabolism / Q000473:pathology; D010012:Osteogenesis / Q000502:physiology*; D010024:Osteoporosis / Q000473:pathology; D011897:Random Allocation; D012044:Regression Analysis; D016103:Spinal Fractures / Q000473:pathology*; D013223:Statistics as Topic; D013314:Stress, Mechanical