Joint Tensioning Arms With Strain Sensing for Laxity Measurement
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Solution Overview
Problem
The lack of standardized methods for collecting soft-tissue tension/laxity data in joint procedures, particularly in robotically assisted total knee arthroplasty, leads to inconsistent results due to the subjective nature of manual force application during varus/valgus stress quantification.
Innovation Solution
A joint tensioning system with a first and second arm configured to apply a distraction force to a joint, equipped with a sensor device to measure strain, and a computing device to determine the distraction force based on the measured strain, allowing for standardized force application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual force application is used to assess soft-tissue laxity, then the procedure is simple and quick, but the measurement precision and reliability are poor due to subjective variability
Solution Approach 1:
The patent replaces manual mechanical force application with an instrumented tensioning device that uses sensors (load cells, strain gauges) to objectively measure soft-tissue tension. This substitution eliminates subjective variability while providing quantitative data, directly resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The tensioning device acts as an intermediary between the surgeon and the joint, providing standardized force application through articulated arms with known mechanical properties. The device mediates the interaction by translating manual manipulation into precise, measurable forces, thereby improving measurement reliability without requiring the surgeon to directly apply unquantified forces.
2Reliability
If standardized force application is implemented using instrumented devices, then measurement reliability improves, but the ease of operation decreases due to complex device handling
Solution Approach 1:
The tensioning device is designed to perform multiple functions: it applies distraction force, measures soft-tissue tension, and provides real-time feedback to the surgical plan. This multi-functionality consolidates several operations into a single tool, improving reliability while maintaining ease of operation by reducing the number of separate devices and steps required.
Solution Approach 2:
The device incorporates real-time feedback mechanisms where measured soft-tissue tensions are immediately compared against the virtual surgical plan. This feedback loop guides the surgeon's manipulation, making the complex device easier to operate by providing continuous directional guidance and reducing the cognitive load required to interpret measurements.
3Measurement precision
If real-time strain measurement is implemented, then the accuracy of distraction force determination improves, but the device complexity increases due to additional sensor devices
Solution Approach 1:
The patent merges the sensor device with the tensioning device structure, integrating load cells and strain gauges directly into the articulated arms. This combination eliminates the need for separate measurement instruments, reducing overall system complexity while maintaining high measurement precision for distraction force quantification.
Solution Approach 2:
The patent replaces complex mechanical force measurement mechanisms with electrical sensors (load cells, strain gauges) that directly convert mechanical stress into electrical signals. This substitution simplifies the measurement system while improving accuracy, as electronic sensors provide precise, real-time data without the mechanical complexity of traditional force measurement devices.
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 precise and standardized quantification of joint laxity, improving the consistency and accuracy of surgical outcomes by providing real-time feedback on the applied force.
Implementation Method 1
A sensor device is located in the first arm and positioned to measure a strain applied to the first tip based on the distraction force applied to the joint
Data Source
AI summary
A joint tensioning device and methods of use thereof are disclosed. The joint tensioning device includes a flexing arm and a loading arm having a tensioning tip and a loading tip, respectively, configured for insertion into a joint. The flexing arm is coupled to the loading arm such that, during use, the loading arm may be adjusted to separate the tensioning tip and the loading tip to apply a distraction force to the joint. A strain gauge measures strain applied to the flexing arm based on the applied distraction force. The measured strain is used to determine the amount of force applied to the joint. The force data is employed in surgical planning to determine the amount of joint laxity when a particular load is applied to the joint.