Non-ferromagnetic Knee Laxity Measurement Device for MRI Compatibility
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Solution Overview
Problem
Current devices for evaluating knee instability due to ligament ruptures, such as the anterior and posterior cruciate ligaments, lack accuracy and cannot differentiate between patients requiring surgery and those needing physiotherapy, as they interfere with MRI and CAT-scan image processing and do not account for rotational instability or associated injuries.
Innovation Solution
A device using non-ferromagnetic materials like plastics, resins, and carbon fibers that allows precise measurement of knee laxity and rotation within MRI or CAT-scan devices, enabling accurate diagnosis of all ligament-related instabilities and associated injuries by measuring tibial translation and rotation without distorting images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ferromagnetic materials are used in knee laxity measurement devices, then the device can be manufactured with sufficient structural strength, but the device interferes with MRI and CAT-scan image processing
Solution Approach 1:
The patent changes the material parameter from ferromagnetic to non-ferromagnetic materials, enabling the device to be used in MRI and CAT-scan environments without interfering with image processing while maintaining sufficient structural strength through material selection and design optimization
Solution Approach 2:
The device employs composite materials that combine non-ferromagnetic properties with adequate mechanical strength, allowing it to function both as a structural measurement device and as an MRI/CAT-scan compatible instrument without image interference
2Ease of manufacture
If external measurement methods are used to measure tibial translation, then the device can be manufactured simply, but the measurement accuracy is reduced due to muscle mass and soft tissue compression variability
Solution Approach 1:
The patent replaces external mechanical measurement methods with internal imaging-based measurement, where MRI or CAT-scan images directly visualize the tibial translation between bone structures, eliminating the influence of soft tissue compression and muscle mass variability on measurement accuracy
3Device complexity
If measurement is limited to anterior and posterior cruciate ligaments, then the device can be designed for specific function, but it cannot evaluate other knee ligaments and associated injuries
Solution Approach 1:
The patent designs a universal measurement device that can evaluate all knee ligaments (anterior and posterior cruciate ligaments, postero-internal and postero-external capsules) and associated injuries (meniscus, cartilage) through comprehensive imaging-based measurement protocols, rather than being limited to specific ligament evaluation
4Device complexity
If rotation control is not considered in the measurement device, then the device design is simplified, but it cannot distinguish patients needing different surgical techniques
Solution Approach 1:
The patent adds rotational measurement capability to the device, incorporating internal rotation and external rotation assessments in addition to anterior-posterior translation measurements, thereby providing comprehensive knee instability evaluation that enables differentiation between patients requiring different surgical techniques with varying rotation control
Data Source
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AI summary
The present invention relates to a device (1) for measuring the knee laxity, with or without use of additional means of diagnosis such as computed axial tomography and magnetic resonance imaging, evaluating the instability of the knee due to rupture of any ligament, namely the anterior cruciate ligament, posterior cruciate ligament, postero-internal capsule, postero-external capsule, as well as around the axis of an orthonormal referential, that comprises three parts respectively to accept and retain the thigh, leg and foot. The device (1) includes independent means (20) and (21) to push backward the anterior zone of the leg and to push forward the posterior zone of the leg, and independent means (12) and (13) to push the part (5) for support and fixation of the foot in clockwise direction and in anti-clockwise direction.