Knee Prosthesis Tibial Condylar Surface Design
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Solution Overview
Problem
Conventional knee prostheses with tibial implants have limited flexion angles due to direct contact between tibial and femoral components during knee bending, restricting smooth luxation and rotation.
Innovation Solution
The lateral condylar bearing surface of the tibial implant features a downwardly sloping end section with a convex transition, allowing for trouble-free luxation and rotation, while the medial condylar surface is shaped as a depression to maintain contact area stability, and an additional dorsal bearing surface facilitates the return rotation of the femur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lateral condylar bearing surface has a downwardly sloping end section, then luxation during knee flexion is facilitated and range of motion is improved, but the structure becomes more complex
Solution Approach 1:
The lateral condylar bearing surface is segmented into multiple functional zones: a first bearing surface for initial contact, a downwardly sloping end section for facilitating luxation during flexion, and a second bearing surface for support during extended flexion. This segmentation allows each zone to perform its specific function optimally, improving ease of operation while managing complexity through functional differentiation.
Solution Approach 2:
Different regions of the bearing surface are given different geometric properties tailored to their specific functions. The downwardly sloping end section has a specific inclination angle (10-30 degrees) to facilitate luxation, while other regions have different curvatures and orientations optimized for their respective roles. This local quality optimization improves performance without requiring complete redesign of the entire structure.
2Stability of the object's composition
If the medial condylar bearing surface is shaped as a depression widening in the dorsal direction, then contact area stability is maintained during flexion, but manufacturing precision requirements increase
Solution Approach 1:
The medial condylar bearing surface is designed as a depression with specific geometric parameters: it widens in the dorsal direction and has a controlled curvature profile. These parameter changes are optimized to maintain contact area stability during flexion while remaining compatible with standard manufacturing capabilities. The depression geometry is carefully calibrated to balance performance improvement with manufacturability.
Data Source
AI summary
The invention relates to a knee prosthesis with a tibial part (1) that has concave or plane condylar bearing surfaces (2, 3). According to the invention, the lateral condylar bearing surface (2) merges into a preferably convex end portion (4) that falls away in the dorsal direction.