Variability in reference point microindentation and recommendations for testing cortical bone: Maximum load, sample orientation, mode of use, sample preparation and measurement spacing

Jenkins, T.; Coutts, Louise V.; Dunlop, D.G.; Oreffo, Richard O.C.; Cooper, Cyrus; Harvey, Nicholas C.; Thurner, Philipp J.

doi:10.1016/j.jmbbm.2014.09.030

Cited by 15 publications

(39 citation statements)

References 34 publications

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“…Repeat RPI measurements on the surface of the same bone, with greater than 2 mm spacing, when a 10 N maximum load was applied, have shown that both IDI and CID results approximate a bell curve where greater than 20 measurements were taken (Jenkins et al, 2015). Within samples, repeat measurements under the same test conditions were therefore combined using the arithmetic mean.…”

Section: Discussionmentioning

confidence: 99%

“…Where possible, settings followed recommendations previously described by the authors (Jenkins et al, 2015) where RPI testing was analysed to determine how RPI repeatability may be optimised. These recommendations included: repeat measurements to reduce variability; maintain consistent sample orientation, mode of use and surface preparation throughout testing; remove the periosteum; ensure a sample thickness 10 fold greater than the maximum indentation depth with a minimum thickness of 500 mm; ensure a minimum measurement spacing of 500 mm and avoid previously tested areas; focus on the IDI and CID measures rather than TID unless the touchdown point is clearly discernable.…”

Section: Discussionmentioning

confidence: 99%

“…4a and b, for IDI and CID respectively. Variability in measurements is likely to occur for three reasons: (1) device variation (Jenkins et al, 2015), (2) regional heterogeneity in bone or 3) variation due to bone disease and damage. However, separating these three effects is difficult, as multiple testing cannot be performed at the same site, due to any previous indentation modifying tissue structure and thus affecting subsequent test results.…”

Section: Discussionmentioning

confidence: 99%

“…All tests were conducted by the same person to eliminate inter-observer variability. Ten repeat tests on PMMA indicated a coefficient of variation of the order of 5.3% (Jenkins et al, 2015). A minimum separation of 2 mm was used between each test site to avoid any influence from the previous indentation.…”

Section: Reference Point Microindentationmentioning

confidence: 99%

“…Therefore, to aid development of an optimum method for future in vitro study of disease related changes in RPI, human and bovine femoral neck and head tissue have been investigated in this study, to provide an a priori understanding of how RPI typically varies with test location, at this critical site. The present study follows an investigation by the current authors (Jenkins et al, 2015) that describes how to acquire repeatable RPI data. In brief, measurements should be performed on regions of cortical or subchondral bone thicker than 500 μm and multiple measurements must be undertaken at each test site, no closer in proximity than 500 μm.…”

Section: Introductionmentioning

confidence: 99%

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Variability in reference point microindentation and recommendations for testing cortical bone: Location, thickness and orientation heterogeneity

Coutts

Jenkins

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Reference Point Microindentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Variability in reference point microindentation and recommendations for testing cortical bone: Location, thickness and orientation heterogeneity

Coutts

Jenkins

et al. 2015

Journal of the Mechanical Behavior of Biomedical Materials

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True Gold or Pyrite: A Review of Reference Point Indentation for Assessing Bone Mechanical Properties In Vivo

Allen

McNerny

Organ

et al. 2015

Journal of Bone and Mineral Research

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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 emerged in several papers. In this review we overview 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 non-fracture 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.

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Site-Dependent Reference Point Microindentation Complements Clinical Measures for Improved Fracture Risk Assessment at the Human Femoral Neck

Jenkins

Coutts

D’Angelo

et al. 2015

Journal of Bone and Mineral Research

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In contrast to traditional approaches to fracture risk assessment using clinical risk factors and bone mineral density (BMD), a new technique, reference point microindentation (RPI), permits direct assessment of bone quality; in vivo tibial RPI measurements appear to discriminate patients with a fragility fracture from controls. However, it is unclear how this relates to the site of the most clinically devastating fracture, the femoral neck, and whether RPI provides information complementary to that from existing assessments. Femoral neck samples were collected at surgery after low-trauma hip fracture (n ¼ 46; 17 male; aged 83 [interquartile range 77-87] years) and compared, using RPI (Biodent Hfc), with 16 cadaveric control samples, free from bone disease (7 male; aged 65 years). A subset of fracture patients returned for dual-energy X-ray absorptiometry (DXA) assessment (Hologic Discovery) and, for the controls, a micro-computed tomography setup (HMX, Nikon) was used to replicate DXA scans. The indentation depth was greater in femoral neck samples from osteoporotic fracture patients than controls (p < 0.001), which persisted with adjustment for age, sex, body mass index (BMI), and height (p < 0.001) but was site-dependent, being less pronounced in the inferomedial region. RPI demonstrated good discrimination between fracture and controls using receiver-operating characteristic (ROC) analyses (area under the curve [AUC] ¼ 0.79 to 0.89), and a model combining RPI to clinical risk factors or BMD performed better than the individual components (AUC ¼ 0.88 to 0.99). In conclusion, RPI at the femoral neck discriminated fracture cases from controls independent of BMD and traditional risk factors but dependent on location. The clinical RPI device may, therefore, supplement risk assessment and requires testing in prospective cohorts and comparison between the clinically accessible tibia and the femoral neck.

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Variability in reference point microindentation and recommendations for testing cortical bone: Maximum load, sample orientation, mode of use, sample preparation and measurement spacing

Cited by 15 publications

References 34 publications

Variability in reference point microindentation and recommendations for testing cortical bone: Location, thickness and orientation heterogeneity

Variability in reference point microindentation and recommendations for testing cortical bone: Location, thickness and orientation heterogeneity

True Gold or Pyrite: A Review of Reference Point Indentation for Assessing Bone Mechanical Properties In Vivo

Site-Dependent Reference Point Microindentation Complements Clinical Measures for Improved Fracture Risk Assessment at the Human Femoral Neck

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