Force Sensor for Knee Ligament Balancing
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Solution Overview
Problem
Balancing ligament tension during knee replacement surgeries is challenging due to the complex dynamic motion of the knee joint, leading to instability, limited range of motion, and uneven wear of prosthetic devices, with existing methods being subjective and lacking standardization.
Innovation Solution
A system comprising a force sensor with a thin force sensing distal portion and a proximal handle portion, equipped with a sensor element and a visual display, is used to measure forces in the knee joint, providing accurate and quantifiable measurements of ligament tension, allowing for standardized and repeatable balancing of ligament tension before making final bone cuts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional subjective methods are used to balance ligament tension, then the surgical process is simple, but the measurement precision and reliability are poor
Solution Approach 1:
The patent replaces subjective mechanical assessment methods with an electronic force sensing system. A force sensor with sensor element converts mechanical ligament tension forces into electrical signals that can be objectively measured and displayed, eliminating reliance on surgeon subjectivity while providing quantifiable data for precise ligament balancing.
Solution Approach 2:
The force sensor acts as an intermediary device between the ligament tissue and the measurement system. It is positioned in the joint space to directly sense ligament tension forces, serving as a mediator that translates biological mechanical forces into readable electrical signals for surgical decision-making.
2Reliability
If ligament tension is not properly balanced, then the surgery is faster, but the stability and range of motion of the prosthetic knee joint deteriorate
Solution Approach 1:
The system provides real-time feedback during surgery by displaying measured ligament tension forces on a visual display. This allows the surgeon to immediately assess whether ligament balancing is adequate and make adjustments before completing the procedure, ensuring reliable prosthetic knee joint stability without requiring multiple revision surgeries.
Solution Approach 2:
The force sensor enables preliminary assessment of ligament tension balancing before final bone cuts are made. By measuring forces during trial assembly, the surgeon can determine the appropriate amount of bone to remove and the orientation of cuts, performing the balancing action in advance to ensure optimal joint stability.
3Manufacturing precision
If no quantitative measurement is used, then the surgical procedure is simpler, but the repeatability and standardization of the procedure are poor
Solution Approach 1:
The patent replaces informal mechanical assessment with a standardized electronic measurement system. The force sensor provides consistent, repeatable measurements of ligament tension forces across different patients and surgeons, enabling standardization of the ligament balancing procedure and reducing variability in surgical outcomes.
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
The system enables precise and standardized ligament tension balancing, improving the range of motion, stability, and patellar tracking of the prosthetic knee joint, reducing the need for repeat surgeries and enhancing the accuracy of knee replacement procedures.
Implementation Method 1
a sensor element... adapted to detect forces in the knee joint
Data Source
AI summary
Systems, devices, and methods are provided for measuring forces in the space of a knee during surgery. Such forces can be caused by tension in the ligaments of the knee. A femoral member is engaged with a distal femur. While the knee is flexed, partially extended, or fully extended, a force sensor and a gauge shim can be placed in the gap between the femoral member and the tibial plateau to measure the forces therebetween. The force sensor provides an accurate and quantifiable measurement of force, making knee replacement surgery and ligament tension balancing more accurate, standardized and repeatable. The force sensor comprises an elongate housing which comprises a thin force sensing distal portion and a proximal handle portion.