The tissue diagnostic instrument

Abstract

Tissue mechanical properties reflect extracellular matrix composition and organization, and as such, their changes can be a signature of disease. Examples of such diseases include intervertebral disk degeneration, cancer, atherosclerosis, osteoarthritis, osteoporosis, and tooth decay. Here we introduce the tissue diagnostic instrument (TDI), a device designed to probe the mechanical properties of normal and diseased soft and hard tissues not only in the laboratory but also in patients. The TDI can distinguish between the nucleus and the annulus of spinal disks, between young and degenerated cartilage, and between normal and cancerous mammary glands. It can quantify the elastic modulus and hardness of the wet dentin left in a cavity after excavation. It can perform an indentation test of bone tissue, quantifying the indentation depth increase and other mechanical parameters. With local anesthesia and disposable, sterile, probe assemblies, there has been neither pain nor complications in tests on patients. We anticipate that this unique device will facilitate research on many tissue systems in living organisms, including plants, leading to new insights into disease mechanisms and methods for their early detection.

The Effects of Freezing on the Mechanical Properties of Bone

“…In a concerted effort to develop a reliable method to directly quantify fracture risk in living patients in a noninvasive manner, we have developed a new diagnostic instrument, the Reference Point Indentation Instrument [4] (RPI) (aka. Tissue Diagnostic Instrument [5], Bone Diagnostic Instrument [6][7][8], and Osteoprobe [9]) that uses a controlled indentation protocol to investigate the micro-mechanical response of the tibia to a defined loading regime. Clinical trials by Diez-Perez have shown the RPI to be successful at discriminating between patients with and without fragility fracture [4].…”

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

“…Thus, the distance measured with the strain gauge is the same as the distance that the probe further indents into the sample from the reference point. The elimination of the reference probe has the advantage of simplicity and of removing the possibility of soft tissue buildup and friction between the test probe and the reference probe as in other RPI Devices [7][8][9][10]. Further detail of the instrument operation has been reported previously by Bridges et al [19].…”

“…V R , was correlated with the BioDent V R [7][8][9][10] and a standard Vickers hardness test. Cadaver samples of cortical bone were excised from the mid diaphysis of the tibia from two 83-year-old female donors.…”

“…On a large scale, this is clearly impractical; however, on a microscopic scale, one can induce microfractures safely. Recently, a new technique, RPI [7][8][9][10], has been reported to quantify the ability of bone to resist indentation in vivo and can also distinguish between the bone of patients with and without fracture [7]. It does so by inducing microfractures in the bone (Fig.…”

Deep atomic force microscopy

“…[5][6][7][8][9] We are interested in using long range AFM to study fractured bone, a sample with rough topography and deep features exceeding the actuation range of conventional AFM. Since the development of the Reference Point Indenter (RPI), [10][11][12][13][14][15] an instrument which directly quantifies bone fracture resistance by creating an indent in bone and measuring the depth of the indent produced, we have been eager to image these indents with long range AFM. Previously, we developed a long range AFM based on voice coil actuation with a range of the order of 1 mm in each axis.…”