Interchangeable Knee Prosthesis Components for Anatomical Fit
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Solution Overview
Problem
Current fixed-bearing knee prostheses are limited by the need for matching sizes of femoral and tibial components, which restricts flexibility in accommodating varying patient anatomy, and do not allow for adjustable sizing to fit different tibial trays and bearings effectively.
Innovation Solution
A fixed-bearing knee prosthesis design featuring a femoral component with medial and lateral condyle surfaces, a bearing with articulating surfaces, and a tibial tray with adjustable posterior and anterior buttresses and recesses, allowing for secure snap-fit attachment and accommodating various sizes of tibial trays and bearings, enabling greater flexibility in matching patient anatomy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If matching sizes of femoral and tibial components are used, then proper articulation is achieved, but flexibility in accommodating varying patient anatomy is restricted
Solution Approach 1:
The tibial tray is designed with a universal interface system comprising standardized recesses and corresponding protrusions that can accommodate multiple bearing sizes. The buttress structure with specifically oriented undercuts creates a universal mounting mechanism that works across different component sizes, allowing one tibial tray design to serve multiple sizing configurations.
Solution Approach 2:
The prosthesis is divided into separable components (tibial tray, bearing, femoral component) with standardized interface features. The bearing can be independently selected and attached to the tibial tray based on patient anatomy requirements, while the femoral component remains separate. This segmentation allows flexible combination of components with different size specifications.
2Adaptability or versatility
If multiple bearing sizes are provided for a particular size of femoral component, then adaptability improves, but each bearing size must be matched to a particular size of tibial tray
Solution Approach 1:
The tibial tray incorporates a universal attachment mechanism with standardized recess dimensions and orientations that can receive multiple bearing sizes. The protrusion geometry and undercut orientations are designed to accommodate various bearing diameters and thicknesses, allowing a single tibial tray to universally mount different bearing options without requiring size-specific tray variations.
3Reliability
If a secure fit between bearing and tibial tray is achieved, then micromotion is reduced, but interchangeability of differently-sized components is limited
Solution Approach 1:
The attachment mechanism features dynamic geometric relationships where the undercut orientations (first and second undercuts in the buttress, third undercut in the anterior buttress) are specifically angled to create secure mechanical interlocking. The protrusions engage these undercuts at optimized angles that provide reliable retention while maintaining standardized interface dimensions that allow interchangeability across different component sizes.
Data Source
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AI summary
A fixed-bearing prosthesis (10) includes a femoral component (12) having a medial condyle surface (32) and a lateral condyle surface (30). A bearing (16) has a medial bearing surface (28) configured to articulate with the medial condyle surface of the femoral component, and a lateral bearing surface (26) configured to articulate with the lateral condyle surface of the femoral component. A tibial tray (14) is secured to the bearing. The tibial tray has a platform (18) with an elongated stem (20) extending downwardly from a lower surface (22) thereof. A posterior buttress (44) extends along a posterior section of the perimeter of the tray's platform, and an anterior buttress (64) extends along an anterior section of the perimeter of the tray's platform. Differently-sized tibial trays are interchangeable with differently-sized bearings.