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Noninvasive Determination of Bone Mechanical Properties using Vibration Response: A Refined Model and Validation in vivoAccurate non-invasive mechanical measurement of long bones is made difficult by the masking effect of surrounding soft tissues. Mechanical Response Tissue Analysis (MRTA) offers a method for separating the effects of the soft tissue and bone; however, a direct validation has been lacking. A theoretical analysis of wave propagation through the compressed tissue revealed a strong mass effect dependent on the relative accelerations of the probe and bone. The previous mathematical model of the bone and overlying tissue system was reconfigured to incorporate the theoretical finding. This newer model (six-parameter) was used to interpret results using MRTA to determine bone cross-sectional bending stiffness, EI(sub MRTA). The relationship between EI(MRTA) and theoretical EI values for padded aluminum rods was R(exp 2) = 0.999. A biological validation followed using monkey tibias. Each bone was tested in vivo with the MRTA instrument. Postmortem, the same tibias were excised and tested to failure in three-point bending to determine EI(sub 3-PT) and maximum load. Diaphyseal Bone Mineral Density (BMD) measurements were also made. The relationship between E(sub 3-PT) and in vivo EI(sub MRTA) using the six-parameter model is strong (R(exp 2) = 0.947) and better than that using the older model (R(exp 2) = 0.645). EI(MRTA) and BMD are also highly correlated (R(exp 2) = 0.853). MRTA measurements in vivo and BMD ex vivo are both good predictors of scaled maximum strength (R(exp 2) = 0.915 and R(exp 2) = 0.894, respectively). This is the first biological validation of a non-invasive mechanical measurement of bone by comparison to actual values. The MRTA technique has potential clinical value for assessing long-bone mechanical properties.
Document ID
19980021299
Acquisition Source
Ames Research Center
Document Type
Contractor Report (CR)
Authors
Roberts, S. G.
(Stanford Univ. Stanford, CA United States)
Hutchinson, T. M.
(NASA Ames Research Center Moffett Field, CA United States)
Arnaud, S. B.
(NASA Ames Research Center Moffett Field, CA United States)
Steele, C. R.
(Stanford Univ. Stanford, CA United States)
Kiratli, B. J.
(California Univ. Davis, CA United States)
Martin, R. B.
(California Univ. Davis, CA United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1996
Publication Information
Publication: Journal of Biomechanics
Publisher: Elsevier Science Ltd.
Volume: 29
Issue: 1
ISSN: 0021-9290
Subject Category
Aerospace Medicine
Report/Patent Number
NASA/CR-96-207209
NAS 1.26:207209
Funding Number(s)
PROJECT: RTOP 106-30-43-04
PROJECT: RTOP 199-26-12-02
Distribution Limits
Public
Copyright
Public Use Permitted.
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