Bone Stiffness Measurement via Frequency Response Analysis
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Solution Overview
Problem
Current methods for determining bone stiffness in vivo are limited, as they cannot differentiate between skin compression and bone bending, require invasive procedures, and often fail to accurately predict bone strength due to their inability to measure mechanical properties directly.
Innovation Solution
A parametric model-based computer implemented method and system that applies static and oscillatory forces to a skin-bone complex to measure oscillatory accelerations, transforming the data into frequency response functions to fit a parametric mathematical model, allowing for the determination of bone stiffness without invasive procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current methods are used to determine bone stiffness, then measurement can be performed, but the methods cannot differentiate between skin compression and bone bending, leading to inaccurate measurements
Solution Approach 1:
The patent segments the skin-bone complex into separate components (skin and bone) by applying oscillatory forces at frequencies that selectively excite each component. The skin responds at lower frequencies while the bone responds at higher frequencies, allowing independent measurement of each component's mechanical properties and accurate determination of bone stiffness without contamination from skin compression.
Solution Approach 2:
The patent applies oscillatory forces at multiple frequencies to the skin-bone complex, utilizing mechanical vibration to selectively excite different components. By sweeping through a frequency range and identifying resonant frequencies specific to bone vibration, the method isolates bone response from skin response, enabling precise bone stiffness measurement.
2Measurement precision
If invasive procedures are used to measure bone mechanical properties, then direct measurement is possible, but the procedures require surgery or bone exposure
Solution Approach 1:
The patent replaces invasive mechanical testing (which requires direct bone access and often fracturing) with non-invasive oscillatory force application and frequency response analysis. By measuring the resonant frequency and vibration characteristics of the skin-bone complex, the method derives bone mechanical properties without physical invasion, surgery, or bone damage.
Solution Approach 2:
The patent uses oscillatory forces at specific frequencies as an intermediary to indirectly measure bone properties. Rather than directly loading and testing the bone, the method applies controlled vibrations that propagate through the skin-bone system, and the frequency response serves as a mediator that reveals bone stiffness and strength characteristics without direct contact or invasion.
3Ease of operation
If simple force application methods are used, then the procedure is easy to perform, but the methods fail to accurately predict bone strength
Solution Approach 1:
The patent applies periodic oscillatory forces at multiple frequencies rather than a single static force. By sweeping through a frequency range and analyzing the periodic response at each frequency, the method extracts detailed mechanical properties including resonant frequency, damping characteristics, and stiffness. This periodic multi-frequency approach maintains procedural simplicity while dramatically improving bone strength prediction accuracy.
Solution Approach 2:
The patent transitions from static force application to dynamic oscillatory forcing. By applying forces that vary with time at multiple frequencies and analyzing the dynamic response, the method captures the frequency-dependent mechanical behavior of bone, providing more accurate predictions of bone strength under various loading conditions while keeping the procedure simple and non-invasive.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables non-invasive, accurate measurement of bone stiffness by differentiating between skin and bone responses, improving the prediction of bone strength and reducing measurement errors.
Implementation Method 1
applying a superposition of static and oscillatory forces (F) over a range of frequencies (f) to a region of a skin-bone complex thereby exciting oscillatory accelerations (a) over the range of frequencies (f) of the skin-bone complex
Data Source
AI summary
Parametric model based computer implemented methods for determining the stiffness of a bone, systems for estimating h the stiffness of a bone in vivo, and methods for determining the stiffness of a bone. The computer implemented methods include determining a complex compliance frequency response function Y(f) and an associated complex stiffness frequency response function H(f) and independently fitting a parametric mathematical model to Y(f) and to H(f), and using a first measure of conformity and a second measure of conformity of the collected data to determine accuracy and repeatability of measurements. The systems include a device for measuring the stiffness of the bone in vivo and a data analyzer to determine a complex compliance frequency response function Y(f) and an associated complex stiffness frequency response function H(f).