Article

A new method for measurement of bone deformation by echo tracking.

Department of Orthopaedic Surgery, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033, Japan.
Medical Engineering & Physics (impact factor: 1.62). 08/2006; 28(6):588-95. DOI:10.1016/j.medengphy.2005.09.005 pp.588-95
Source: PubMed

ABSTRACT No method has been available to noninvasively detect bone deformation or strain under loading in vivo. We focused on ultrasonic measurement of the displacement at a certain point on a bone using the echo-tracking method (ET). To develop a method that can noninvasively detect bone deformation in vivo, a preliminary investigation was performed. We investigated the accuracy of measuring displacement with our echo tracking system by using a flat metal panel and found that the method could measure displacement with a precision of a few microns. A three-point bending test of a porcine tibia with both ends fully constrained was performed to measure bone surface displacement, and simultaneous measurement of the surface strain was done using two strain gauges. The correlation between the displacement measured by ET and the strain gauge readings was completely linear (r=0.999), showing that the method could precisely detect bone deformation. The loads versus displacement curves obtained with cyclic loading were typical hysteresis loops that showed viscoelastic properties of the measured bone. We also improved a multi-ET system capable of simultaneously tracking multiple points to detect deformation of the bone surface. Measurement by this echo tracking system was also compared with strain gauge readings during a three point bending test with both ends of the tibia supported. The linearity of both methods was very high (r=0.998). Our ET method might have considerable potential for noninvasive measurement of bone viscoelasticity and plasticity.

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Keywords

bone deformation
 
bone surface
 
bone viscoelasticity
 
certain point
 
cyclic loading
 
echo-tracking method
 
ET method
 
flat metal panel
 
measure bone surface displacement
 
measured bone
 
multi-ET system capable
 
noninvasive measurement
 
porcine tibia
 
preliminary investigation
 
showed viscoelastic properties
 
simultaneous measurement
 
strain gauge readings
 
strain gauges
 
surface strain
 
ultrasonic measurement
 

J Matsuyama