Surgical Aid for Knee Joint Isometry Maintenance

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Solution Overview

Problem

Traditional surgical techniques for knee joint prosthetics alter the tension of peri-articular and intra-articular capsule-ligamentous tissues during bone resections, leading to unsatisfactory clinical results and pain, as they prioritize alignment with the mechanical or anatomical axis over maintaining isometric tissue tension.

Innovation Solution

A surgical aid comprising a first and second element positioned on the femur and tibia, respectively, with an actuator and sensors to maintain isometric tension of capsule-ligamentous tissues by measuring displacement and force, allowing precise alignment and resection planning to ensure optimal prosthetic positioning and kinematics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional surgical techniques align bone resections with the mechanical or anatomical axis, then the prosthetic components achieve proper alignment, but the capsule-ligamentous tissues experience altered tension leading to pain and unsatisfactory clinical results

Engineering Contradiction:
Improvealignment precisionVSAvoidtissue tension alteration
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The surgical aid incorporates sensors that provide real-time feedback on the tension state of capsule-ligamentous tissues during bone resection. This feedback mechanism allows the surgeon to adjust the resection parameters to maintain isometric tension in the soft tissues while achieving proper prosthetic alignment, thereby resolving the contradiction between alignment precision and tissue tension preservation

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The invention replaces traditional mechanical alignment methods with a sensor-based system that uses electronic measurement and control. Instead of relying solely on mechanical guides and anatomical landmarks, the system uses sensors to detect tissue tension and provides data-driven guidance for bone resection, enabling simultaneous achievement of precise alignment and isometric tissue tension

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If asymmetric bone resections are performed to accommodate anatomical variations, then the prosthetic components can be positioned correctly, but the soft tissues become excessively tensioned requiring surgical release

Engineering Contradiction:
Improveanatomical adaptationVSAvoidsoft tissue integrity
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The surgical aid system dynamically adjusts the bone resection plan based on real-time sensor feedback regarding soft tissue tension. Rather than committing to a fixed asymmetric resection pattern, the system allows continuous modification of resection parameters during surgery to maintain optimal tissue tension, adapting to actual anatomical conditions while preserving soft tissue integrity

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the parameters of bone resection (such as resection depth, angle, and location) based on sensor measurements of soft tissue tension. By dynamically adjusting these parameters during surgery, the system can accommodate anatomical variations and achieve proper prosthetic positioning without creating excessive tissue tension that would require surgical release

Inventive Principle:
Principle #35Parameter changes

3Volume of moving object

If the extensor mechanism is reduced to position the surgical aid, then compact positioning is achieved, but the intervention time may be extended

Engineering Contradiction:
Improvedevice compactnessVSAvoidsurgery duration
Core Design Contradiction:
Volume of moving objectVSLoss of time

Solution Approach 1:

The surgical aid is positioned with the extensor mechanism reduced as a preliminary step before the main prosthetic implantation. This preliminary positioning allows the compact device to be installed and configured in advance, enabling it to guide the subsequent bone resections and component positioning efficiently, thereby minimizing the overall surgery duration despite the initial setup step

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3270832B1A surgical aid for joints
Publication Date: 2019.05.01 MANTOVANI
  • EP3270832B1 patent drawingFigure 1~2
  • EP3270832B1 patent drawingFigure 3~4
  • EP3270832B1 patent drawingFigure 5~6

AI summary

A surgical aid for joints which allows the positioning of mono-compartment or three-compartment prosthetic components so that the isometry of the capsular-ligament tissues of the knee is maintained during the entire range of motion. Such surgical aid comprises: a first element (10) intended to be positioned in contact with a first bone of a joint; a second element (20), intended to be positioned in contact with a second bone of the joint; the first and second element (10,20) being movable relatively to one another along at least a first direction (X); a displacement sensor (30) predisposed for measuring a relative displacement between the first and second element (10,20); an actuator/motor (50) predisposed for exerting a force that tends to move the first element (10) and second element (20) away from one another; a pressure sensor (40) which measures the force that is exerted between the first and second bone; a processing module (60) arranged to control the actuator/motor (50) so as to calculate the variation of the slope arising from the relationship between distance and force; the processing module (60) receives in input the signal emitted by the displacement sensor (30), the force sensor (10) and the pressure sensor (40).