Knee Prosthetic Implant with Conforming Facet Surfaces
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Solution Overview
Problem
Current knee prosthetic implants face challenges in achieving stability and full range of motion due to difficulties in adjusting and maintaining ligament tension, leading to joint instability or restricted motion.
Innovation Solution
The design incorporates sets of cooperating convex and concave facet surfaces within the prosthesis joint compartment to provide stability and a large range of motion, independent of primary ligament tension, accommodating three ranges of knee motion through conforming interfacing surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If knee prosthetic implants use a mechanical hinge design with single-axis rotation, then the structure is simple, but the range of motion is limited and the mechanism breaks easily
Solution Approach 1:
The knee prosthesis is divided into separate femoral and tibial components with distinct articulating surfaces. The femoral component includes medial and lateral condyles with specific convex surfaces, while the tibial component has corresponding concave surfaces, allowing independent motion in different compartments
Solution Approach 2:
The articulating surfaces use curved geometries instead of flat planes. The femoral condyles have convex surfaces with specific radii of curvature that match the concave surfaces of the tibial platform, enabling smooth rolling and gliding motions that replicate natural knee kinematics
2Stability of the object's composition
If knee prosthetic implants rely on ligament tension for stability, then the joint stability is maintained, but the range of motion becomes restricted and ligament adjustment is difficult
Solution Approach 1:
The prosthesis design allows the joint to self-regulate stability through its geometric features. The cam-like effect of the distal medial articular surface and the conforming interfacing surfaces automatically maintain joint stability and control ligament tension throughout the range of motion without requiring external adjustment mechanisms
Solution Approach 2:
The design incorporates variable curvature radii in the articulating surfaces. The femoral condyles have different radii of curvature in different regions, allowing the contact point to migrate during flexion and extension, which dynamically adjusts the mechanical constraints and maintains stability across the full range of motion
3Stability of the object's composition
If knee prosthetic implants use conforming surfaces for stability, then joint stability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The conforming surfaces are segmented into distinct zones with specific functions. The medial and lateral compartments have different surface geometries optimized for their respective kinematic requirements, allowing each zone to be manufactured and adjusted independently
Solution Approach 2:
The prosthesis components are designed with pre-configured surface geometries that establish proper alignment and conformity upon implantation. The cam-like effects and arcuate paths are built into the component design, requiring minimal intraoperative adjustment to achieve optimal surface contact and joint stability
Data Source
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AI summary
A human knee prosthetic implant having a tibia component forming first and second medial concave surfaces and first and second lateral concave surfaces, and a femur component forming first and second medial convex surfaces and first and second lateral convex surfaces. The tibia and femur surfaces are formed to provide contact interaction in full extension, a mid flexion range and in a state of full flexion of the knee prosthetic implant.