Knee Prosthesis Bayonet Joint Fixation for Wear Reduction
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Solution Overview
Problem
Existing knee prostheses require separate components for primary total knee arthroplasty and revision procedures, leading to material inefficiency and increased backside wear due to screw installation methods, which compromise the stability and thickness of tibial and femoral components.
Innovation Solution
A prosthetic component with a bayonet joint connection using an insert and fastening element that engages through a spacing element, allowing for a thinner main body and minimizing surface roughness and wear, while providing a durable connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a screw is installed through the tibial component into the spacing element, then the spacing element can be fixed to the tibial component, but backside wear of the inlay is increased due to surface roughness and screw head protrusion
Solution Approach 1:
An insert is introduced as an intermediary component between the screw and the tibial component. The insert receives the screw and provides a bearing surface, preventing the screw head from directly contacting and roughening the inlay receiving surface of the tibial component, thereby eliminating backside wear while maintaining fixation strength
Solution Approach 2:
The fixation mechanism is segmented into separate functional components: the tibial component, the insert (separated from the tibial component), and the screw. This segmentation allows the insert to bear the mechanical load and surface contact, protecting the critical inlay receiving surface of the tibial component from wear
2Object-affected harmful factors
If a screw is installed through the spacing element into the tibial component, then backside wear is decreased, but the main body thickness must be increased to provide sufficient thread depth
Solution Approach 1:
The insert acts as a mediator that provides the thread reception function without requiring the tibial component main body to have sufficient thickness. The screw threads engage with the insert, not the tibial component directly, allowing a thinner main body design while maintaining secure fixation
Solution Approach 2:
The thread reception function is extracted from the tibial component main body and transferred to a separate insert. This extraction allows the main body to be thinner since it no longer needs to accommodate deep threads, while the insert provides the necessary thread engagement for screw fixation
3Ease of manufacture
If separate tibial components are provided for primary and revision procedures, then each component can be optimized for its specific use, but material usage increases and device complexity increases
Solution Approach 1:
The tibial component is designed with universal applicability for both primary total knee arthroplasty and revision procedures. The key feature is the receiving portion that can accommodate inserts, allowing the same tibial component design to serve multiple functions - primary implantation and revision with spacing elements - thereby reducing the need for separate component inventories and material usage
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A prosthetic component (2) adapted to be mounted to a bone as part of a knee prosthesis comprises a spacing element for compensating resected bone. The prosthetic component (2) further comprises a main body (6) with a contact surface (7) configured to abut the spacing element and a fixation mechanism (9) for fixing the spacing element between the contact surface (7) and the bone. The fixation mechanism (9) comprises a receiving portion (10) located at the contact surface (7). The fixation mechanism (9) further comprises an insert (11) for insertion into the receiving portion (10) and a fastening element adapted to engage with the insert (11). The receiving portion (10) is adapted to fix the insert (11) via a bayonet joint connection such that the fastening element, extending through the spacing element and engaging with the insert (11), fixes the spacing element to the contact surface (7).