Femur-Tibia Positioning Device Using Multi-Height Sensors
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Solution Overview
Problem
Current devices for determining the relative position of a femur with respect to a tibia are not precise enough, as they rely on rough approximations and cannot make direct contact with the femur, making it difficult to accurately assess the joint's geometry for total knee prosthesis placement.
Innovation Solution
A device comprising multiple measuring members positioned on the tibia and femur, using sensors and accelerometers to generate signals that are processed to determine the absolute and relative positions, allowing for precise joint analysis by cross-referencing measurements taken at different heights on the thigh.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single sensor is placed on the tibia and femur to determine the angle between them, then the device structure is simple, but the measurement precision is insufficient due to rough approximation
Solution Approach 1:
The device divides the measurement system into multiple independent measuring units: a first measuring unit on the tibia and at least two measuring units on the femur at different heights. Each unit independently measures its local position and orientation, and the calculating unit processes these segmented measurements to compute the relative angle, thereby improving measurement precision while keeping each individual unit simple
Solution Approach 2:
The invention adds the dimension of height by placing measuring units at different vertical positions on the femur (first height and second height). This multi-level arrangement allows the system to capture three-dimensional spatial relationships and calculate the femur-tibia angle more accurately by cross-referencing measurements from multiple heights, transforming a two-dimensional approximation into a three-dimensional measurement
2Measurement precision
If direct contact sensors are used on the femur, then the measurement precision would improve, but it is not possible due to the thickness of skin and soft tissue
Solution Approach 1:
The measuring units on the femur serve as intermediaries that do not require direct contact with the bone. Instead of placing sensors directly on the femur (which is blocked by skin and soft tissue), the device uses external measuring units that detect the position and orientation of the femur through the soft tissue layer, thereby obtaining measurement data without direct bone contact
Solution Approach 2:
By positioning measuring units at different heights on the femur, the system creates a multi-dimensional measurement framework that can infer the femur's spatial orientation and position without requiring direct contact sensors. The multi-height arrangement allows calculation of the femur's angular position relative to the tibia through geometric relationships
3Measurement precision
If multiple measuring devices are placed at different heights on the femur, then the absolute position of the femur can be determined more accurately, but the device complexity increases
Solution Approach 1:
The system segments the femur measurement into multiple independent units positioned at different heights. Each measuring unit is a self-contained module that measures local position and orientation, and the calculating unit processes these segmented measurements to determine the overall femur position and the femur-tibia angle, improving precision while maintaining modular simplicity
Solution Approach 2:
The measuring units are designed to be multi-functional: they can measure position, orientation, and angular relationships. The same type of measuring unit can be placed at multiple heights on the femur, and the system can determine both the absolute position of the femur and the relative angle between femur and tibia using these universal measuring units
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 more precise determination of the relative position of the femur with respect to the tibia, improving the accuracy of knee joint analysis and aiding in the design of more effective total knee prostheses.
Implementation Method 1
each comprising means for generating a signal representative of a position of the associated measuring device
Data Source
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AI summary
DEVICE FOR DETERMINING A RELATIVE POSITION OF A FEMUR WITH RESPECT TO A TIBIA The invention relates to a device for determining a relative position of a femur (F) with respect to a tibia (T) comprising at least: - a first measuring member (4) intended to be 10 positioned against the tibia and comprising means (11) for collecting an absolute position of the tibia and means (12) for generating a signal representing this position - a second and a third measuring member (20; 30) 15 intended to be positioned relatively to the femur by each surrounding the thigh (2) associated with the femur at different heights, the second and third measuring member each comprising means (55) for generating a signal representing a position of the 20 associated measuring member; - a calculating member (100) comprising communication means (101) for receiving at least the signals generated by the first, second and third measuring members, comparison means (102) which 25 compare the signals of the second and third members in order to deduce an absolute position of the femur and processing means (103) which analyze the signal of the first measuring member and the absolute position of the femur in order to deduce a relative 30 position of the femur with respect to the tibia. Figure 1 5650802_1 (GHMatters) P97782.AU BELAG '41) Fig.1