Interchangeable Knee Prosthesis Components with Snap-Fit Fixation
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Solution Overview
Problem
Current fixed-bearing knee prostheses have limited flexibility in sizing, as they are typically provided in matching sizes for femoral and tibial components, which can restrict their adaptability to varying patient anatomies, and they lack efficient mechanisms to prevent micromotion and ensure stable fixation.
Innovation Solution
The design includes a femoral component with medial and lateral condyle surfaces, a bearing with articulating surfaces, and a tibial tray with Y-shaped and T-shaped buttresses and recesses, allowing for secure snap-fit assembly and adjustable sizing, reducing micromotion and accommodating different patient anatomies through interchangeable components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fixed-bearing knee prosthesis components are provided in matching sizes, then manufacturing and inventory management are simplified, but adaptability to varying patient anatomies is restricted
Solution Approach 1:
The prosthesis system is divided into separable components (femoral component, tibial tray, and bearing) that can be independently sized and selected. The bearing is detachable from the tibial tray, allowing the surgeon to mix and match different sizes and configurations to achieve optimal fit for each patient's anatomy while maintaining standardized manufacturing of individual components.
2Stability of the object's composition
If bearing is fixed to tibial tray, then structural stability is improved, but micromotion between components cannot be prevented
Solution Approach 1:
The bearing is designed with a dynamic retention system featuring posterior tabs that engage with corresponding recesses in the tibial tray. This allows the bearing to be securely retained during normal function while enabling controlled adjustment and removal when needed, providing both stability during use and flexibility for correction of micromotion issues.
Solution Approach 2:
The bearing contains nested retention features (posterior tabs) that fit into corresponding recesses in the tibial tray, creating a nested structure that provides stable fixation while allowing for controlled movement and adjustment to prevent micromotion.
3Device complexity
If bearing size is matched to tibial tray size, then assembly is simplified, but flexibility in optimizing articulation surfaces is lost
Solution Approach 1:
The bearing is made detachable from the tibial tray, segmenting the assembly into separate components that can be independently selected and optimized. This allows the surgeon to choose the optimal bearing size for the femoral component's articulation surface regardless of the tibial tray size, while the standardized interface simplifies assembly.
Data Source
AI summary
A fixed-bearing prosthesis includes a femoral component having a medial condyle surface and a lateral condyle surface. The knee prosthesis also includes a bearing having a medial bearing surface configured to articulate with the medial condyle surface of the femoral component, and a lateral bearing surface configured to articulate with the lateral condyle surface of the femoral component. A tibial tray is secured to the bearing. The tibial tray has a platform with an elongated stem extending downwardly from a lower surface thereof. A posterior buttress extends along a posterior section of the perimeter of the tray's platform, and an anterior buttress extends along an anterior section of the perimeter of the tray's platform. Differently-sized tibial trays are interchangeable with differently-sized bearings.