Tibial Prosthesis Dovetail Securement Mechanism
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Solution Overview
Problem
Current tibial prostheses experience micromotion issues due to material deformation and slight clearances between components, which can lead to instability and discomfort during natural knee articulation, and existing solutions do not effectively prevent lift-off and transverse movement of the bearing component relative to the tibial tray.
Innovation Solution
A fixed bearing tibial prosthesis with a two-pronged securement mechanism, including a dovetail boss and peripheral rail locking system, which provides a secure fit and guides the insertion trajectory of the bearing component onto the tibial tray, minimizing micromotion and eliminating the need for secondary locking mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bearing component is secured to a tibial tray using conventional locking mechanisms, then the bearing component is fixed in position, but micromotion still occurs due to material deformation and clearances
Solution Approach 1:
The securement mechanism is divided into two distinct functional elements: a dovetail boss for preventing lift-off and a peripheral rail system for preventing transverse movement. This segmentation allows each element to address specific micromotion vectors independently, providing comprehensive stabilization without requiring excessive interference fits that would cause material deformation.
Solution Approach 2:
The dovetail boss is nested within a corresponding recess in the bearing component, while the peripheral rail is nested within a groove on the bearing component. This nested configuration creates interlocking joints that eliminate clearances between components, preventing micromotion while maintaining material integrity without requiring excessive force.
2Reliability
If existing locking mechanisms are used to prevent bearing component movement, then some stability is achieved, but lift-off and transverse movement are not effectively prevented
Solution Approach 1:
The combined dovetail boss and peripheral rail system performs multiple functions simultaneously: the dovetail boss prevents lift-off while the peripheral rail prevents transverse movement in all directions. This multi-functional design eliminates the need for separate secondary locking mechanisms, achieving comprehensive movement prevention with a unified securement system.
3Ease of operation
If material deformation is allowed to accommodate clearances between components, then assembly is easier, but micromotion increases causing instability
Solution Approach 1:
The dovetail boss and peripheral rail are designed with precise preliminary dimensions that create interference-free interlocking joints. The boss fits into a recess and the rail fits into a groove with predetermined clearances that eliminate the need for material deformation during assembly, achieving both ease of assembly and elimination of micromotion through pre-engineered fit tolerances.
Data Source
AI summary
A tibial prosthesis, and, particularly, a fixed bearing tibial prosthesis is disclosed that has a two-pronged securement mechanism. The securement mechanism may or may not be angled. Advantageously, the securement mechanism, working alone or in cooperation with other securement features, minimizes micromotion between the tibial tray and tibial bearing component.