Interchangeable Knee Prosthesis Components
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Solution Overview
Problem
Current fixed-bearing knee prostheses are limited in flexibility as they are typically available in matching sizes for femoral and tibial components, restricting the ability to accommodate varying patient anatomy and requiring multiple sizes for each component, which can complicate surgical procedures.
Innovation Solution
A fixed-bearing knee prosthesis design featuring a tibial tray with a Y-shaped posterior buttress and T-shaped anterior buttress, allowing for secure snap-fit attachment of a bearing with adjustable sizing, enabling compatibility across a range of tibial tray and bearing sizes, thereby enhancing flexibility and interchangeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If matching sizes are used for femoral and tibial components, then proper articulation is ensured, but flexibility in accommodating varying patient anatomy is reduced
Solution Approach 1:
The prosthesis is divided into separate modular components: a tibial tray component and a bearing component. The bearing can be detached and replaced independently from the tibial tray, allowing different bearing sizes to be used with the same tibial tray. This segmentation enables flexibility in component sizing while maintaining proper articulation through the designed interface between the bearing and tibial tray.
Solution Approach 2:
The tibial tray component is designed with a universal interface that can accommodate multiple bearing sizes. The Y-shaped posterior buttress and T-shaped anterior buttress create a standardized mounting structure that can securely hold bearings of varying dimensions, allowing one tibial tray to serve multiple functions with different bearing options.
2Adaptability or versatility
If multiple sizes of each component are provided, then flexibility in matching components is improved, but device complexity and surgical procedure complexity increase
Solution Approach 1:
By separating the bearing from the tibial tray as independent replaceable components, the system reduces the need for multiple complete prosthesis sets. Surgeons can use a single tibial tray size and simply exchange bearings of different sizes, thereby reducing overall device complexity while maintaining flexibility.
Solution Approach 2:
A single tibial tray design with standardized buttress structures can accommodate multiple bearing sizes, reducing the total number of unique component combinations needed. This universal interface approach simplifies the overall system by allowing one tibial tray to serve multiple sizing configurations.
3Adaptability or versatility
If multiple sizes of each component are provided, then flexibility in matching components is improved, but surgical procedure complexity increases
Solution Approach 1:
The bearing is designed as a separate, independently replaceable component that can be quickly exchanged during surgery without requiring removal or replacement of the entire tibial tray assembly. This segmentation simplifies the surgical workflow when size adjustments are needed.
Solution Approach 2:
The Y-shaped and T-shaped buttresses are pre-formed integral structures on the tibial tray, eliminating the need for additional assembly steps or complex alignment procedures during surgery. The bearing simply snaps into these pre-prepared receptacles, streamlining the surgical process.
4Reliability
If secure attachment of bearing to tibial tray is achieved, then micromotion is reduced, but device complexity increases
Solution Approach 1:
The combination of Y-shaped posterior buttress and T-shaped anterior buttress creates an asymmetric, interlocking geometry that provides secure attachment. The bearing's recesses are shaped to complement these asymmetric buttress forms, creating a snap-fit connection that resists micromotion through geometric interlocking rather than complex fastening mechanisms.
Solution Approach 2:
The bearing and tibial tray features are designed to automatically engage and lock together through the snap-fit mechanism formed by the buttresses and recesses. This self-securing connection eliminates the need for additional fasteners, screws, or complex attachment procedures, achieving secure attachment while maintaining design simplicity.
Data Source
Figure 1
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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). The knee prosthesis also includes a bearing (16) having 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 (50) of the perimeter of the tray's platform, and an anterior buttress (64) extends along an anterior section (70) of the perimeter of the tray's platform. Differently-sized tibial trays are interchangeable with differently-sized bearings.