Offset Morse Taper Shoulder Implant for Easier Disassembly
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Solution Overview
Problem
Current reverse shoulder prostheses face challenges in manufacturing due to central alignment of sphere and baseplate, leading to limited articulation, difficulty in disassembly, and potential tissue and bone damage during extraction.
Innovation Solution
The development of humeral replacement prostheses with an offset post and locking screw design allows for easier assembly and disassembly, enabling a greater range of articulation and adaptability to different shoulder sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a modular design with separate baseplate and articulating component is used, then ease of manufacture and inventory management are improved, but device complexity increases due to multiple components requiring assembly
Solution Approach 1:
The implant system is divided into separate modular components: a baseplate and an articulating component. Each component can be manufactured independently using optimized processes, and they are designed to be assembled together in the surgical procedure. This segmentation allows each part to be produced with specialized manufacturing techniques while maintaining overall system functionality.
Solution Approach 2:
The baseplate is designed as a universal component that can accommodate different articulating components through standardized coupling mechanisms. The baseplate includes features such as a coupling component with a bore and positioning features that can work with various articulating component designs, allowing one baseplate to serve multiple functions with different articulating surfaces or geometries.
2Strength
If traditional fixation methods are used, then manufacturing simplicity is maintained, but fixation strength and prevention of micromotion are insufficient
Solution Approach 1:
The fixation component is designed with a nested structure that includes an outer shell and an inner core, with the inner core fitting within the outer shell. This nested design provides multiple fixation surfaces and mechanisms within a compact component, increasing fixation strength without proportionally increasing overall component size or complexity.
Solution Approach 2:
The fixation component utilizes composite construction with different materials or material properties in different regions of the component. This allows optimization of each region for its specific function: some areas provide structural strength, while others provide fixation surfaces or flexibility, achieving superior overall fixation performance.
3Strength
If the articulating component is made as a single solid piece, then structural strength is improved, but stress shielding occurs due to lack of flexibility
Solution Approach 1:
The articulating component features local quality variations with different regions having different material properties or structural characteristics. Some regions are designed with higher density or stiffness to provide structural strength, while other regions have reduced density or increased flexibility to allow controlled micromotion and prevent stress shielding. This local differentiation optimizes both strength and biological integration.
Solution Approach 2:
The articulating component incorporates porous material structures in specific regions to reduce overall density while maintaining local strength. The porous structure allows for bone ingrowth and provides flexibility to reduce stress shielding effects, while strategic placement of denser material regions ensures adequate structural support for load-bearing functions.
4Stability of the object's composition
If the baseplate is made thick and robust, then fixation stability is improved, but the implant profile increases making it less suitable for anatomic shoulder anatomy
Solution Approach 1:
The baseplate incorporates nested structural elements where internal components are positioned within cavities or recesses of the baseplate body. This nesting arrangement maintains structural stability through the nested configuration while minimizing the external profile of the baseplate, allowing it to conform better to the anatomic shoulder geometry.
Solution Approach 2:
The baseplate design utilizes three-dimensional structural optimization with varying thickness profiles and internal geometry. Rather than being uniformly thick, the baseplate has strategic thickening in areas requiring fixation stability while being thin in areas where profile matters. Internal reinforcement structures provide strength without increasing external dimensions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design facilitates easier manufacturing, reduces costs, and minimizes tissue and bone damage during disassembly, providing a more versatile and adaptable prosthesis.
Implementation Method 1
The fixation component can be held within the cavity by a spring and cap
Implementation Method 2
The baseplate includes a first Morse taper that is offset from a center line of the baseplate
Data Source
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AI summary
An implant is disclosed that has a base member, an articulating member, and a coupling portion that secures the base member to the articulating member. A shoulder implant that has a baseplate, an articulating component, and a fixation component is disclosed. The baseplate includes a first side that has a first Morse taper that is offset from a center line of the baseplate and a second side that has a post that is offset from the center line of the baseplate. The articulating component is attachable to the baseplate. The articulating component includes a second Morse taper that is offset from a center of the articulating component. A threaded through hole extends from a first side of the articulating component to a second side thereof. The through hole can be aligned with the second Morse taper. The fixation component can engage the through hole and is contained within a cavity of the baseplate by a spring and a cap.