Applications of a New Handheld Reference Point Indentation Instrument Measuring Bone Material Strength

Abstract

A novel, hand-held Reference Point Indentation (RPI) instrument, measures how well the bone of living patients and large animals resists indentation. The results presented here are reported in terms of Bone Material Strength, which is a normalized measure of how well the bone resists indentation, and is inversely related to the indentation distance into the bone. We present examples of the instrument's use in: (1) laboratory experiments on bone, including experiments through a layer of soft tissue, (2) three human clinical trials, two ongoing in Barcelona and at the Mayo Clinic, and one completed in Portland, OR, and (3) two ongoing horse clinical trials, one at Purdue University and another at Alamo Pintado Stables in California. The instrument is capable of measuring consistent values when testing through soft tissue such as skin and periosteum, and does so handheld, an improvement over previous Reference Point Indentation instruments. Measurements conducted on horses showed reproducible results when testing the horse through tissue or on bare bone. In the human clinical trials, reasonable and consistent values were obtained, suggesting the Osteoprobe V R is capable of measuring Bone Material Strength in vivo, but larger studies are needed to determine the efficacy of the instrument's use in medical diagnosis.

Trabecular bone score (TBS) as a new complementary approach for osteoporosis evaluation in clinical practice

“…Apart from BMD, FRAX does not capture other skeletal determinants of bone strength that improve upon or are at least partly independent of aBMD [10]. Several such determinants are the subject of clinical research [11][12][13][14][15][16][17][18] using novel imaging techniques, such as Quantitative Computed Tomography (QCT) and high resolution (peripheral) QCT [19,20], and minimally invasive approaches for probing bone material properties, notably microindentation techniques [21]. Although there is evidence of their predictive ability for fracture [22,23] , none of these modalities appears to reliably outperform aBMD in the prediction of the various types of osteoporotic fractures, and their general lack of availability and validation in the clinical setting means that an adjunctive role alongside DXA-measured aBMD is unlikely to be feasible in most settings in the near future.…”

Skeletal changes through the lifespan—from growth to senescence

“…The availability of a novel microindentation device might now enable the safe measurement of properties of bone material (bone material strength index) in humans. 52,53 Using a prototype device (called a reference point indenter), several small studies found that indices of properties of bone material might be reduced in patients with hip fractures 54 and atypical femoral fractures. 55 The potential utility of this approach for assessing properties of bone material in humans was demonstrated in a proof-of-concept study.…”

Technical note: Recommendations for a standard procedure to assess cortical bone at the tissue-level in vivo using impact microindentation

“…The latter method, impact microindentation, is now utilized in living humans, and is performed using a hand-held RPI device (OsteoProbe® RUO Reference Point Indenter, Active Life Scientific, Santa Barbara, CA, USA) that imparts a single impact load to the bone surface. The handheld OsteoProbe is more amenable for clinical use than the BioDent, which requires a stand to perform measurements in human patients (Randall et al, 2013). Both techniques have been recently reviewed (Allen et al, 2015).…”