Knee Alignment Sensor Assembly for Precise Compression Measurement
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Solution Overview
Problem
Current tools for achieving balance of forces and proper operation of knee prostheses during knee replacement surgery are limited by precision, accessibility, adaptability, and interference issues, particularly in measuring compression forces between components.
Innovation Solution
A novel precision knee alignment tool with a sensor assembly featuring a rigid base and flexible cover design, along with a gooseneck cable and calibration apparatus, to accurately measure compression forces without interference, and a dual-blade cutting saw for precise bone cuts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid housing is used to enclose the sensor assembly, then structural stability is improved, but measurement precision deteriorates due to interference from the housing during compression
Solution Approach 1:
The housing is segmented into rigid and flexible portions. The rigid portions provide structural stability while the flexible portions (including the flexible cover and flexible circuit board) allow accurate force transmission to sensors without interference, resolving the contradiction between stability and measurement precision
Solution Approach 2:
Different portions of the housing have different mechanical properties - rigid portions for structural support and flexible portions for force transmission. This local differentiation allows the housing to simultaneously provide stability while enabling precise measurements by allowing compression forces to reach sensors without being distorted by rigid housing interference
2Volume of moving object
If sensor assemblies are positioned close together to reduce device size, then device compactness is improved, but measurement precision deteriorates due to cross-interference between sensors
Solution Approach 1:
The sensor assembly is segmented with individual flexible covers over each sensor and flexible circuit boards for each sensor channel. This segmentation allows sensors to be positioned close together while each sensor's measurement path remains independent, preventing cross-interference and maintaining precision in a compact form factor
Solution Approach 2:
Flexible circuit boards serve as intermediaries between the sensors and the rigid housing structure. These flexible intermediaries allow each sensor to independently transmit its measurement signal without mechanical coupling or cross-interference between adjacent sensors, enabling high-density sensor placement while maintaining measurement precision
3Manufacturing precision
If advanced navigation systems and robotic assistance are used, then manufacturing precision of bone cuts is improved, but device complexity and cost increase
Solution Approach 1:
The sensor assembly acts as an intermediary measurement tool that provides real-time feedback on compression forces during surgery. This relatively simple sensor-based system complements navigation systems by providing direct mechanical feedback, reducing reliance on complex computational systems while maintaining high precision in implant placement
Solution Approach 2:
The sensor assembly autonomously measures and reports compression forces without requiring complex external systems. The self-contained sensor assembly with integrated flexible circuitry provides independent measurement capability, reducing the need for complex external navigation and control systems while maintaining surgical precision
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
Enhances the precision and adaptability of knee replacement surgery by providing independent force measurements and ensuring parallel bone cuts, improving the longevity and functionality of the replacement knee.
Implementation Method 1
compression forces between components of a knee replacement prosthesis
Implementation Method 2
pressure sensors positioned between the femoral and tibial components
Data Source
AI summary
A knee alignment measurement tool for use during a total knee replacement surgery may include the following main components: a sensor assembly, a display unit configured to power up, operatively control the individual sensors of the sensor assembly, and display the readings therefrom, and a flexible cable operatively connecting the sensor assembly to the display unit. The sensor assembly may include a rigid base supporting a circuit board, a left sensor and a right sensor positioned adjacent to the left center, and a cover sealed to the rigid base to enclose the left sensor and the right sensor, wherein the cover does not abut the rigid base during the compression of the sensor assembly.