External Fixator Struts with Strain Gauges for Bone Healing Monitoring
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Solution Overview
Problem
Current external fixation devices for stabilizing bone fractures lack effective methods to determine the state of bone healing, leading to variable healing rates and potential re-fracture risks, as they rely on inconclusive x-rays and clinical judgment.
Innovation Solution
Incorporating modified struts with strain gauges attached to a smooth center section, connected to an electronic module that measures and records mechanical strains on the struts, allowing for non-invasive monitoring of bone healing through mechanical force analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If external fixation devices are used to stabilize bone fractures, then bone stability is improved, but the ability to accurately determine bone healing status deteriorates due to reliance on inconclusive x-rays and clinical judgment
Solution Approach 1:
The patent replaces the conventional mechanical/radiological assessment system (x-rays and clinical judgment) with an electronic sensing system. Strain gauges are attached to the external fixator struts to convert mechanical strain information into electrical signals, enabling precise, real-time monitoring of bone healing status through quantitative force measurements rather than indirect imaging.
Solution Approach 2:
The patent introduces strain gauges as intermediary sensing elements between the external fixator structure and the measurement system. These gauges act as mediators that detect mechanical forces on the struts and transmit this information to the data processing system, providing an indirect but accurate measurement of bone healing status without requiring direct contact with the bone or reliance on x-ray imaging.
2Reliability
If the external fixator is kept on the patient for extended periods to ensure adequate healing, then bone healing reliability is improved, but patient quality of life and risk of infection deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where strain gauge measurements continuously monitor bone healing progress and provide real-time information to clinicians. This feedback loop enables early detection of healing milestones, allowing the fixator to be removed as soon as adequate healing is achieved, thereby minimizing the duration of patient intrusiveness and infection risk while maintaining high healing reliability.
Solution Approach 2:
The patent enables preliminary detection of healing status through continuous strain monitoring, allowing clinicians to anticipate when healing will be sufficient for fixator removal. This preliminary assessment capability prevents both premature removal (which would compromise healing reliability) and unnecessary prolonged retention (which would increase infection risk and patient burden).
3Measurement precision
If strain gauges are attached to the external fixator struts to measure mechanical forces, then measurement precision of bone healing status is improved, but device complexity increases
Solution Approach 1:
The patent leverages the existing external fixator structure to serve multiple functions: mechanical stabilization of the fracture and simultaneous host for strain gauge attachment. The struts perform dual roles as both structural support elements and sensing platforms, eliminating the need for separate sensing devices and reducing overall system complexity despite the added measurement capability.
Solution Approach 2:
The patent applies strain gauges only to specific locations on the external fixator struts where mechanical forces are most indicative of bone healing status. This localized sensing approach concentrates measurement resources on critical areas rather than requiring comprehensive instrumentation of the entire device, thereby improving measurement precision while minimizing the added complexity and cost.
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
Provides accurate and reliable indicators of bone healing status, enabling clinicians to determine when to remove the fixator and preventing further complications by quantifying mechanical forces on the struts and foot plantar forces, thus optimizing treatment.
Implementation Method 1
one or more strain gauges configured to measure the mechanical strains acting on the modified strut
Data Source
AI summary
A device for and a method of monitoring the healing status of a fractured bone in a person's limb is disclosed. The external fixation device may include one or more rods or struts that incorporate strain gauges designed to measure the mechanical forces on the strut when force is applied to the fractured bone. The mechanical force data may be collected by an electronic module and transmitted to a computer for statistical analysis. The device may also include a foot insole sensor for measuring the foot plantar force to normalize the data collected by an external fixation device attached to a person's leg. The method of measuring the healing status of a fractured bone includes measuring the changes in mechanical forces exerted on the one or more struts, and based on the measurements, estimating the healing status of the bone.