External Fixation Strut Length Measurement with Threaded-Rod Sensing
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Solution Overview
Problem
Existing external fixation systems face challenges in accurately and efficiently measuring strut lengths during bone deformity correction procedures, leading to potential human error and time inefficiencies, especially when relying on manual measurements or x-ray imaging.
Innovation Solution
The implementation of adjustable-length struts with mechanisms such as fluctuation counters, optical sensors, ultrasonic sensors, and electrically conductive loops to precisely determine strut length changes, utilizing gear mechanisms and controller modules for automated or manual adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual measurement methods are used to determine strut lengths, then the measurement process is simple to implement, but human error increases and measurement precision deteriorates
Solution Approach 1:
The patent replaces manual visual estimation and physical measuring tools with automated sensing systems including optical sensors, ultrasonic sensors, and image processing algorithms. These systems automatically capture and analyze the positions of measurement markers on the strut to calculate precise length measurements, eliminating human error while maintaining implementation feasibility through standardized sensor integration.
Solution Approach 2:
The patent uses image capture devices to create digital copies of the strut and its measurement markers. By processing these optical copies through image analysis algorithms, the system determines strut length without requiring direct physical contact or manual measurement, thereby improving precision while keeping the overall device complexity manageable through software-based solutions.
2Measurement precision
If x-ray imaging is used to measure strut lengths, then measurement precision can be improved, but time consumption increases and the process becomes less efficient
Solution Approach 1:
The patent incorporates measurement markers directly onto the strut components during manufacturing. These pre-positioned markers enable immediate optical detection and measurement without requiring post-assembly imaging procedures. The measurement capability is built into the structure itself, allowing rapid assessment that does not delay the correction procedure.
Solution Approach 2:
The patent substitutes x-ray imaging with optical sensing systems including cameras and ultrasonic sensors. These systems provide real-time or near-real-time measurements through non-ionizing methods, dramatically reducing measurement time while maintaining or improving precision through digital image processing and automated calculation algorithms.
3Productivity
If automated sensing systems are implemented for strut measurement, then measurement speed and precision are improved, but device complexity increases
Solution Approach 1:
The patent integrates multiple sensing modalities (optical sensors, ultrasonic sensors, image capture devices) into a unified measurement system that can determine various strut parameters including length, position, and orientation. This multi-functional approach improves measurement speed and comprehensiveness while managing complexity through shared processing hardware and integrated control algorithms that handle multiple sensor inputs simultaneously.
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
Enables accurate, rapid, and objective measurement of strut lengths, reducing human error and time consumption, and facilitating precise bone deformity corrections through automated or manual strut length determination.
Implementation Method 1
The free end of the needle is configured to maintain contact with the threaded rod. While the threaded rod moves into or out of the tube, the free end of the needle may be configured to maintain contact with the threaded rod by riding along peaks and valleys of threads of the threaded rod.
Implementation Method 2
The fluctuation counter may be configured to count a total number of fluctuations as the free end of the needle rides along peaks and valleys of threads of the threaded rod, with one fluctuation corresponding to one complete revolution of the threaded rod.
Implementation Method 3
determining a total length change of the strut by multiplying the total number of fluctuation cycles by a pitch of the threaded rod
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
A strut for use with an external fixation system may include first and second joints proximate the first and second ends of the strut, the first and second joints configured to couple to first and second rings of the external fixation system. The strut may include a threaded rod coupled to the first joint, a tube that receives the threaded rod, a fluctuation counter coupled to the tube, and a needle coupled to the fluctuation counter. The needle may extend through a bore in the outer tube, and the needle may have a free end in contact with the threaded rod. The strut may be an adjustable-length strut whereby the threaded rod is moveable axially into or out of the tube, and while the threaded rod moves into or out of the tube, the free end of the needle may be configured to maintain contact with the threaded rod.