Rotating Hinged-Knee Prosthesis Modular Insert Design
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Solution Overview
Problem
Current knee prostheses lack the ability to accurately replicate the complex range of motion and articulation of a natural human knee, particularly in the flexion and extension movements, leading to suboptimal functional outcomes during 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 rotation about two axes, enabling a range of motion from -3 to 140 degrees of flexion and an additional 3 to 10 degrees of secondary rotation, mimicking the natural knee's articulation through a hinged mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed hinge mechanism is used to couple femoral and tibial components, then mechanical constraint and stability are improved, but the ability to replicate natural knee range of motion is worsened
Solution Approach 1:
The hinge mechanism incorporates a dynamic adjustment feature that allows the axis of rotation to shift position along the hinge pin during knee flexion and extension. This dynamic characteristic enables the prosthesis to adapt to varying ranges of motion while maintaining mechanical constraint through the hinge structure.
Solution Approach 2:
The invention changes the parameter of the hinge axis position, allowing it to vary along the length of the hinge pin. This parameter change enables the prosthesis to replicate different ranges of motion by adjusting where along the pin the effective rotation occurs, thereby improving adaptability while maintaining structural reliability.
2Adaptability or versatility
If a modular insert design is implemented, then adaptability and customization of range of motion are improved, but device complexity is worsened
Solution Approach 1:
The insert is divided into modular components including a tibial insert and a femoral insert that can be independently positioned and adjusted. This segmentation allows for customization of the range of motion by selecting and assembling different insert configurations, while each individual component remains relatively simple in structure.
Solution Approach 2:
The modular insert acts as an intermediary element between the femoral and tibial components, providing the mechanism for range of motion adjustment. This intermediary structure enables customization without requiring complex modifications to the primary femoral or tibial components themselves.
3Device complexity
If the hinge axis is fixed in position, then structural simplicity is improved, but the ability to mimic natural knee articulation is worsened
Solution Approach 1:
Rather than fixing the hinge axis at a single predetermined location, the design allows the effective hinge axis to dynamically shift to different positions along the hinge pin depending on the knee's flexion angle and loading conditions. This dynamic behavior mimics natural knee articulation more accurately while maintaining a relatively simple hinge structure.
Solution Approach 2:
The invention adds a longitudinal dimension to the hinge axis position, allowing it to shift along the length of the hinge pin. This dimensional freedom enables more accurate replication of natural knee articulation paths without requiring a completely complex multi-axis mechanism.
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
This system provides enhanced mobility and flexibility during knee replacement surgeries, allowing for precise adjustment and customization of the range of motion, thereby improving the functional alignment and movement of the prosthetic knee, closely mimicking the natural knee's articulation.
Implementation Method 1
the tibial insert is configured to rotate relative to the tibial tray
Implementation Method 2
the femoral component is configured to rotate about a first axis relative to the tibial insert over a first range of motion, the first axis extends in a mediolateral direction
Implementation Method 3
the body of the modular insert is configured to rotate relative to the tibial insert about a second axis extending parallel to the first axis over a second range of motion
Implementation Method 4
a tab is coupled to the platform, the tab is configured to engage the outer surface of the base to limit rotation of the tibial insert relative to the tibial tray
Data Source
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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.