title: True Gold or Pyrite: A Review of Reference Point Indentation for Assessing Bone Mechanical Properties In Vivo.
abstract: Although the gold standard for determining bones' mechanical integrity is the direct measure of mechanical properties, clinical evaluation has long relied on surrogates of mechanical properties for assessment of fracture risk. Nearly a decade ago, reference point indentation (RPI) emerged as an innovative way to potentially assess mechanical properties of bone in vivo. Beginning with the BioDent device, and then followed by the newer generation OsteoProbe, this RPI technology has been utilized in several publications. In this review we present an overview of the technology and some important details about the two devices. We also highlight select key studies, focused specifically on the in vivo application of these devices, as a way of synthesizing where the technology stands in 2015. The BioDent machine has been shown, in two clinical reports, to be able to differentiate fracture versus nonfracture patient populations and in preclinical studies to detect treatment effects that are consistent with those quantified using traditional mechanical tests. The OsteoProbe appears able to separate clinical cohorts yet there exists a lack of clarity regarding details of testing, which suggests more rigorous work needs to be undertaken with this machine. Taken together, RPI technology has shown promising results, yet much more work is needed to determine if its theoretical potential to assess mechanical properties in vivo can be realized.
authors.affiliation: Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA.|Department of Medicine-Nephrology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Allen
authors.affiliation: Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Erin Mb
authors.initials: EM
authors.lastname: McNerny
authors.affiliation: Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Organ
authors.affiliation: Department of Biomedical Engineering, Indiana University Purdue University of Indianapolis, Indianapolis, IN, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Wallace
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001842:Bone and Bones / Q000473:pathology*; D015331:Cohort Studies; D004285:Dogs; D005269:Femur / Q000473:pathology; D050723:Fractures, Bone / Q000473:pathology; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007501:Iron / Q000737:chemistry*; D051379:Mice; D051381:Rats; D012016:Reference Values; D013314:Stress, Mechanical; D013440:Sulfides / Q000737:chemistry*
chemical_list: D013440:Sulfides; C011342:pyrite; D006046:Gold; D007501:Iron
keywords: BIODENT; BONE; MECHANICAL PROPERTIES; MICROINDENTATION; OSTEOPROBE; RPI