title: Reference point indentation study of age-related changes in porcine femoral cortical bone.
abstract: The reference point indentation (RPI) method is a microindentation technique involving successive indentation cycles. We employed RPI to measure average stiffness (Ave US), indentation distance increase (IDI), total indentation distance (TID), average energy dissipated (Ave ED), and creep indentation distance (CID) of swine femoral cortical bone (mid-diaphysis) as a function of age (1, 3.5, 6, 14.5, 24, and 48 months) and loading directions (longitudinal and transverse). The Ave US increases with animal age, while the IDI, TID, Ave ED, and CID decrease with age, for both longitudinal (transverse surface) and transverse (periosteal surface) loading directions. Longitudinal measurements generally give higher Ave US and lower IDI and TID values compared to transverse measurements. The RPI measurements show similar trends to those obtained using nanoindentation test, and ash and water content tests.
authors.affiliation: Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W Green Street, Urbana, IL 61801, USA. r_rasulian@yahoo.com
authors.forename: Ramin
authors.initials: R
authors.lastname: Rasoulian
authors.forename: Ahmad
authors.initials: A
authors.lastname: Raeisi Najafi
authors.forename: Michael
authors.initials: M
authors.lastname: Chittenden
authors.forename: Iwona
authors.initials: I
authors.lastname: Jasiuk
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D001696:Biomechanical Phenomena; D005269:Femur / Q000502:physiology*; D013552:Swine