Off-axis Motion Analysis of Knee Joints via Robotic Testing
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Solution Overview
Problem
Current manual tests for knee joint injuries, such as the Lachman, Dial, and Varus-Valgus tests, are subjective and prone to inconsistencies due to clinician variability, leading to inaccurate diagnoses and potential misdiagnosis of ligament damage, especially in complex knee injuries where multiple structures are affected.
Innovation Solution
A robotic testing apparatus that applies forces oriented in primary degrees of freedom to knee joints, capturing data on primary and concomitant movements in multiple degrees of freedom to objectively assess joint conditions, using a free body kinematic framework to analyze off-axis motions and generate load-deformation curves for comprehensive joint evaluation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual tests are used to evaluate knee joint injuries, then the testing process is simple and accessible, but the diagnosis accuracy and measurement precision deteriorate due to clinician subjectivity
Solution Approach 1:
The patent replaces manual mechanical testing with a robotic testing apparatus that uses computer-controlled actuators to apply precise forces and measure joint responses. The robotic system substitutes human clinician actions with automated mechanical systems that can precisely control and measure forces applied to the knee joint, eliminating subjectivity while maintaining operational capability.
Solution Approach 2:
The patent introduces a robotic system as an intermediary between the clinician and the patient's knee joint. This intermediary device objectively measures joint play and ligament compliance through sensors and actuators, translating physical joint movements into quantifiable data that can be analyzed without human subjectivity.
2Measurement precision
If robotic testing apparatus is used to improve measurement precision, then diagnosis accuracy improves, but device complexity increases
Solution Approach 1:
The robotic testing apparatus is divided into separate functional modules: actuators for applying forces, sensors for measuring responses, a control system for coordinating operations, and a data analysis system. This segmentation allows each component to be optimized independently and simplifies maintenance and calibration while maintaining overall system precision.
Solution Approach 2:
The robotic testing apparatus is designed to perform multiple knee joint evaluation functions including measuring anterior-posterior translation, internal-external rotation, varus-valgus angulation, and ligament compliance. This multi-functionality consolidates what would otherwise require multiple separate devices into a single comprehensive system, managing complexity through integration of diverse testing capabilities.
3Productivity
If manual tests are performed by individual clinicians, then the testing process is quick and simple, but reliability and reproducibility deteriorate due to clinician variability
Solution Approach 1:
The robotic testing system incorporates real-time feedback through sensors that continuously monitor joint position, applied forces, and joint play measurements. This feedback is fed back to the control system to maintain precise control during testing and to provide immediate objective data, ensuring consistent and reliable measurements across different patients and testing sessions.
Solution Approach 2:
The system maintains productivity by optimizing testing parameters such as force magnitudes, application rates, and measurement thresholds based on extensive calibration and validation. These parameter settings are standardized across all testing sessions, ensuring that testing remains efficient while achieving high reliability and reproducibility through consistent parameter application.
Data Source
AI summary
A method includes obtaining test data for a joint, the test data being indicative of motion of the joint during joint testing implemented by a robotic testing apparatus applied to the joint to impart force oriented in a first degree of freedom for the joint, generating first data indicative of movement of the joint in the first degree of freedom based on the test data, generating second data indicative of concomitant movement of the joint in a second degree of freedom for the joint based on the test data, the concomitant movement arising from the imparted force, and determining a condition of the joint based on an analysis of the first data and the second data.