Universal Stem Extension for Modular Knee Implants
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Solution Overview
Problem
Existing modular orthopaedic knee implant systems require a substantial number of components, limiting flexibility and increasing inventory needs for surgeons to customize prosthetic knee implants for individual patients.
Innovation Solution
A modular orthopaedic knee implant system that includes a distal femoral component, a proximal tibial component, an adapter, and a stem extension, with a tapered metaphyseal sleeve and femoral adapters that allow for adjustable valgus angles and anterior-posterior offsets, enabling the use of a single set of stem extensions for both tibial and femoral sides, thereby reducing the overall number of components required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing modular orthopaedic knee implant systems use multiple separate stem extensions for femoral and tibial sides, then customization options are provided, but the number of components and inventory requirements increase substantially
Solution Approach 1:
The stem extension is designed with a universal connecting end that can be attached to both the femoral component and the tibial component. The connecting end features a standardized interface that accommodates both sides of the implant system, allowing a single stem extension design to serve multiple functions and reducing the need for separate femoral and tibial stem extensions.
Solution Approach 2:
The implant system is divided into modular components including the femoral component, tibial component, and a separate stem extension that can be selectively attached. This segmentation allows the stem extension to be a standalone universal component rather than being integrated into side-specific assemblies, enabling flexibility while reducing total component count.
2Adaptability or versatility
If multiple side-specific stem extensions are provided for different anatomical configurations, then patient-specific customization is enabled, but surgeon inventory needs increase
Solution Approach 1:
A single universal stem extension design with a standardized connecting end interface replaces the need for multiple side-specific stem extensions. This universal component can be configured for different anatomical requirements through selective attachment to either the femoral or tibial component, thereby reducing inventory complexity while maintaining patient-specific customization capability.
3Manufacturing precision
If separate femoral and tibial stem extensions are used, then proper anatomical alignment is achieved, but the overall system requires more components
Solution Approach 1:
The system separates the alignment function from the side-specific component design. The universal stem extension maintains alignment capabilities through its connecting interface geometry, while the modular segmentation allows it to be selectively attached to either femoral or tibial components, achieving proper anatomical alignment without requiring separate dedicated stem extensions for each side.
Solution Approach 2:
The universal connecting end acts as an intermediary interface between the stem extension and both femoral and tibial components. This standardized interface ensures proper anatomical alignment regardless of which side the stem extension is attached to, while simplifying the overall system by eliminating the need for side-specific connecting geometries.
Data Source
AI summary
A knee implant system includes a femoral adapter. The femoral adapter has a threaded bore so that a stem extension can be threaded onto the proximal end of the adapter. The same stem extension can be threaded onto the distal end of the tibial tray so that the number of stem extensions required in the system is reduced. The femoral adapter has a tapered exterior surface so that a metaphyseal sleeve can be frictionally connected to the femoral adapter. The metaphyseal sleeve has a threaded bore so that the same type of stem extension can be threaded onto the metaphyseal sleeve. The system can include a group of adapters to give the surgeon the option of selecting the appropriate valgus angle and anterior-posterior position of the stem extension.