Adjustable Prosthetic Tibial Component Alignment
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Solution Overview
Problem
Existing prosthetic tibial components for knee joints often experience misalignment between the condyles of the femur and the scalloped seats, leading to reduced stability, excessive wear, and early loosening, due to angular offsets in the anterior-posterior centerlines.
Innovation Solution
A novel prosthetic tibial component with a modular metal base construct and polyethylene bearing construct, featuring adjustable locking rails and a tongue mechanism, allows for precise alignment of the anterior-posterior centerline of the scalloped seats with the condyles, ensuring proper seating and stability through adjustable mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed prosthetic tibial component with predetermined geometry is used, then manufacturing is simplified, but alignment precision between condyles and scalloped seats deteriorates due to angular offsets
Solution Approach 1:
The locking rails are designed to be adjustable in angle relative to the baseplate, allowing the component to adapt from a fixed predetermined geometry to an adjustable configuration. This enables precise alignment of the anterior-posterior centerline of the scalloped seats with the condyles by rotating the locking rails to the optimal angular position, thereby resolving the contradiction between manufacturing simplicity and alignment precision.
Solution Approach 2:
The prosthetic tibial component is divided into separable modules: a baseplate, adjustable locking rails, and a bearing construct. This segmentation allows the locking rails to be independently adjusted relative to the baseplate, enabling precise alignment without requiring the entire component to be manufactured with complex adjustable mechanisms, thus maintaining manufacturing simplicity while achieving high alignment precision.
2Device complexity
If the anterior-posterior centerline of scalloped seats is fixed relative to the baseplate, then device complexity is reduced, but stability and wear resistance deteriorate due to misalignment
Solution Approach 1:
The locking rails incorporate an adjustable angular mechanism that allows them to be rotated relative to the baseplate to achieve the optimal alignment with the femoral condyles. This dynamic adjustment capability, implemented through a relatively simple rotational mechanism with locking features, maintains low device complexity while significantly improving joint stability and reducing wear by ensuring precise alignment of the anterior-posterior centerlines.
3Reliability
If bone integration is optimized through porous surfaces, then osseo-integration improves, but alignment precision may be compromised if the baseplate geometry is fixed
Solution Approach 1:
The baseplate is segmented from the locking rails, allowing the baseplate to be optimized with porous surfaces for bone integration while the locking rails can be independently adjusted to achieve precise alignment. This modular segmentation enables the baseplate geometry to focus on biological integration functions without compromising alignment precision, as the alignment is achieved through adjustment of the separate locking rail component.
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
The solution provides improved alignment and stability between the femoral condyles and the tibial component, reducing wear and loosening, and allowing for optimal bone integration, thereby enhancing the longevity and functionality of the knee joint prosthesis.
Implementation Method 1
bottom surface 43 of baseplate 40 (and, optionally, stem 45 and/or posts 50) comprises a porous material so as to allow bone ingrowth into baseplate 40 (and/or stem 45 and/or posts 50), whereby to facilitate osseo-integration of baseplate 40 (and/or stem 45 and/or posts 50) with resected tibia 15 over time
Data Source
AI summary
A prosthetic tibial component for a knee joint, said prosthetic tibial component comprising:a base construct for engaging the tibia; anda bearing construct for engaging the femoral side of the knee joint;said bearing construct being adjustably fixedly mountable to said base construct.