A new method for measurement of bone deformation by echo tracking

Matsuyama, J.; Ohnishi, I.; Sakai, R.; Suzuki, H.; Harada, A.; Bessho, M.; Matsumoto, T.; Nakamura, K.

doi:10.1016/j.medengphy.2005.09.005

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Volume 28, Issue 6 , Pages 588-595, July 2006

A new method for measurement of bone deformation by echo tracking

J. Matsuyama
- Department of Orthopaedic Surgery, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033, Japan
I. Ohnishi
- Department of Orthopaedic Surgery, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033, Japan
- Corresponding author. Tel.: +81 3 5800 8656; fax: +81 3 3818 4082.
R. Sakai
- Research Laboratory, Aloka Co. Ltd., Tokyo, Japan
H. Suzuki
- Research Laboratory, Aloka Co. Ltd., Tokyo, Japan
A. Harada
- Research Laboratory, Aloka Co. Ltd., Tokyo, Japan
M. Bessho
- Department of Orthopaedic Surgery, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033, Japan
T. Matsumoto
- Department of Orthopaedic Surgery, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033, Japan
K. Nakamura
- Department of Orthopaedic Surgery, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033, Japan

Received 18 February 2005; received in revised form 14 August 2005; accepted 27 September 2005. published online 02 November 2005.

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.

Keywords: Echo tracking, Bone deformation, Noninvasive measurement, Bone strain