Improvements to mechanical response tissue analysis

Lyn Bowman,Anne B Loucks

doi:10.1016/j.mex.2019.10.004

Abstract

Cortical Bone Mechanics Technology™ (CBMT) comprises certain improvements over a previous method known as Mechanical Response Tissue Analysis (MRTA). Both methods are dynamic 3-point bending tests intended for measuring the mechanical properties of cortical bone in living people. MRTA presented a theoretical potential for direct measurement of skeletal fragility, but it had acquired a reputation for error and fallen into disuse. We found sources of error in both MRTA data collection and data analysis. We describe here the fundamentals of MRTA, the major sources of error we found in MRTA, and our innovations for avoiding them.•Data collection at many sites across the mid-shaft of the ulna bone in the forearm.•Parameter estimation by fitting analytical complex compliance and stiffness transfer functions to empirical complex compliance and stiffness frequency response functions.•Optimization by selecting results from frequency response functions with the smallest deviations between fits to compliance and stiffness frequency response functions.

Highlights

We reported the excellent accuracy of a novel non-invasive, radiation-free method for measuring the bending stiffness and estimating the bending strength of cortical bone in ulnas of living people [1]
This method embodies certain improvements over a method known as Mechanical Response Tissue Analysis (MRTA) that had fallen into disuse [2]
Because current clinical methods do not predict fractures well [7,8,9,10], and because MRTA presented a theoretical potential for direct measurement of skeletal fragility, we undertook to discover the major sources of error in MRTA and, if possible, to correct them

Summary

Introduction

MRTA was expected to overcome the clinical limitations of QMT by applying small, rapidly oscillating forces spanning a range of audio frequencies to the skin overlying a long bone. The amount of force required to bend an ulna bone into the linear portion of its range of motion where KB is calculated by QMT is typically more than 100 N.

Results

Conclusion