Quantitative Ultrasound Does Not Reflect Mechanically Induced Damage in Human Cancellous Bone

Authors

  • P. H. F. Nicholson,

    1. Orthopedic Biomechanics Laboratory, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, U.S.A.
    Search for more papers by this author
  • M. L. Bouxsein

    Corresponding author
    1. Orthopedic Biomechanics Laboratory, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, U.S.A.
    • Address reprint requests to: Mary L. Bouxsein, Ph.D., Orthopedic Biomechanics Laboratory, RN115, Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Boston, MA 02215, U.S.A.
    Search for more papers by this author

Abstract

This study investigated the ability of quantitative ultrasound (QUS) to detect reductions in the elastic modulus of cancellous bone caused by mechanical damage. Ultrasonic velocity and attenuation were measured using an in-house parametric imaging system in 46 cancellous bone cores from the human calcaneus. Each core was subjected to a mechanical testing regime to (a) determine the predamage elastic modulus, (b) induce damage by applying specified strains in excess of the yield strain, and (c) measure the postdamage elastic modulus. The specimens were divided into four groups: a control group subjected to a nominally nondestructive 0.7% maximum strain (ϵm) and three damage groups subjected to increasing strain levels (ϵm = 1.5, 3.0, and 4.5%). QUS measurements before and after the mechanical testing showed no significant differences between the control group and damage groups, despite highly significant (p < 0.001) reductions in the elastic modulus of up to 72%. These results indicate that current QUS techniques do not intrinsically reflect the elastic properties of cancellous bone. This is consistent with ultrasonic properties being determined by other factors (apparent density and/or architecture), which normally are associated strongly with elastic properties, but only when bone is mechanically intact. Clinically, this implies that ultrasound cannot be expected to detect bone fragility in the absence of major changes in bone density and/or trabecular architecture.

Ancillary