Rotating Hinged-Knee Prosthesis with Modular Insert
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Solution Overview
Problem
Current knee prostheses lack the ability to accurately replicate the complex articulation and range of motion of a natural human knee, particularly in the flexion and extension movements, which can lead to suboptimal functional outcomes in knee replacement surgeries.
Innovation Solution
The orthopaedic prosthesis system includes a femoral component attached to the femur, a tibial tray attached to the tibia, and a modular insert that allows for specific ranges of motion, enabling the femoral component to rotate relative to the tibial insert and the tibial tray, with adjustable rotation and positioning to mimic the natural knee's movement through a range of flexion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fixed hinge mechanism is used to couple femoral and tibial components, then mechanical stability is improved, but the ability to replicate natural knee range of motion deteriorates
Solution Approach 1:
The prosthesis is divided into multiple independent rotatable components: the tibial insert rotates relative to the tibial tray, and the modular insert rotates relative to the tibial insert. This segmentation allows each component to contribute to different aspects of knee motion, achieving both stability and multi-directional range of motion that mimics natural knee articulation.
Solution Approach 2:
The hinge mechanism transitions from a fixed connection to a dynamic system with multiple degrees of freedom. The first hinge joint allows rotation between the tibial insert and tibial tray, while the second hinge joint allows rotation between the modular insert and tibial insert. This dynamic design enables the prosthesis to adapt its configuration during movement, replicating the complex kinematics of a natural knee while maintaining mechanical stability through controlled articulation.
2Adaptability or versatility
If a modular insert with multiple hinge joints is implemented, then range of motion is improved, but device complexity increases
Solution Approach 1:
The modular insert is received within a cavity in the tibial insert, and the femoral component is received within the modular insert, creating a nested arrangement. This nesting approach allows multiple functional components to be integrated in a compact configuration, reducing the overall space required while maintaining the complexity of multi-joint articulation. The hierarchical structure simplifies the assembly and reduces the number of separate parts needed.
3Measurement precision
If rotation between modular insert and tibial insert is allowed, then articulation accuracy is improved, but manufacturing precision requirements increase
Solution Approach 1:
The modular insert acts as an intermediary component between the femoral component and the tibial insert. It includes a second hinge joint that facilitates controlled rotation and articulation. This intermediary structure provides a defined axis of rotation and controlled degrees of freedom, which simplifies the manufacturing tolerances required for the interfacing surfaces while maintaining high articulation accuracy through the engineered hinge mechanism.
Data Source
AI summary
An orthopaedic prosthesis includes a femoral component configured to be attached to a distal end of a patient's femur. A tibial tray is configured to be attached to a proximal end of a patient's tibia. A tibial insert is configured to rotate relative to the tibial tray. A modular insert is received in a cavity defined in the tibial insert. The femoral component is rotatably coupled to the body of the modular insert.