A new method for measurement of bone deformation by echo tracking

Area of Science:

• Biomechanics
• Biomedical Engineering
• Materials Science

Background:

• Noninvasive in vivo methods for detecting bone deformation and strain under loading are currently unavailable.
• Accurate assessment of bone mechanical properties is crucial for diagnosing and managing skeletal conditions.

Purpose of the Study:

• To develop and validate a noninvasive ultrasonic echo-tracking (ET) method for measuring bone deformation and strain in vivo.
• To assess the accuracy and reliability of the ET method in detecting bone mechanical properties.

Main Methods:

• Developed an echo-tracking (ET) system to measure ultrasonic displacement on bone surfaces.
• Validated the ET system's precision using a flat metal panel, achieving micron-level accuracy.
• Conducted three-point bending tests on porcine tibiae, comparing ET displacement measurements with strain gauge readings.
• Utilized a multi-ET system for simultaneous multi-point tracking of bone surface deformation.

Main Results:

• The ET method demonstrated high precision in measuring displacement (a few microns).
• A strong linear correlation (r=0.999) was observed between ET-measured displacement and strain gauge readings during porcine tibia tests.
• Cyclic loading revealed hysteresis loops, indicating the viscoelastic properties of the bone.
• The multi-ET system also showed high linearity (r=0.998) when compared with strain gauges.

Conclusions:

• The ultrasonic echo-tracking (ET) method provides a precise and noninvasive approach for measuring bone deformation in vivo.
• The ET technique accurately reflects bone strain and can characterize viscoelastic and plastic properties.
• This method holds significant potential for advancing the noninvasive assessment of bone mechanical health.