Acetabular Cup Insertion Cap With Segmented Impaction Plate
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Solution Overview
Problem
Existing prosthetic acetabular cup insertion tools face challenges in securely gripping and positioning thin-walled cups without compromising the structural integrity or articulating properties of the prosthesis, particularly during impaction, repositioning, and extraction, and require multiple tool sizes for different cup sizes, leading to cost and practical issues.
Innovation Solution
A cap with an impaction plate comprising multiple sectors connected by flanges, featuring lugs that engage with recesses on the cup's rim, allowing flexible connection and disconnection to the insertion tool, which minimizes distortion risks and can be used with various cup sizes using a single tool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the insertion tool grips the cup on the inner hemisphere mechanical feature, then the tool can apply impaction forces, but the mechanical feature may not be strong enough and could result in damage to the insertion tool, metal shell or both
Solution Approach 1:
The cap acts as an intermediary component between the insertion tool and the acetabular cup. The cap includes an impaction plate with sectors that can be connected to the insertion tool, and lugs that engage with recesses on the cup's rim. This intermediary structure distributes the impaction forces across multiple engagement points (lugs with recesses) rather than concentrating them on a single mechanical feature on the inner hemisphere, thereby preventing damage to both the tool and the cup while enabling effective impaction forces to be applied.
2Strength
If the wall thickness of the shell is kept to a minimum, then the structural efficiency is improved, but the tool cannot generally grip the wall
Solution Approach 1:
The invention moves the engagement interface from the radial dimension (gripping the thin shell wall) to the axial dimension (engaging the rim from above). The lugs extend downwardly from the underside of the impaction plate and engage with recesses on the rim of the cup, allowing the tool to grip the cup through the cap without requiring the shell wall to be thick enough for direct tool engagement. This dimensional shift enables effective gripping while maintaining minimum wall thickness for structural efficiency.
3Manufacturing precision
If multiple tool sizes are provided for different cup sizes, then the correct fit and engagement is achieved, but cost implications for hospitals arise
Solution Approach 1:
The cap is designed with a standardized engagement interface (lugs fitting into recesses) that can accommodate different cup sizes while maintaining consistent geometric relationships. The impaction plate sectors and lug configurations can be adapted to work with various cup diameters (42mm to 62mm) without requiring fundamentally different tool designs. This universal approach allows a single insertion tool design to work with multiple cap sizes, thereby eliminating the need for hospitals to purchase multiple specialized tools for different cup sizes while still achieving correct fit and engagement.
4Reliability
If the cap provides robust attachment for thin-walled cups, then distortion risk is reduced, but the attachment system must be flexible for connection and disconnection
Solution Approach 1:
The impaction plate is divided into multiple sectors that are mutually connected at a connection point by means of flanges. Each sector includes interlocking means for connection to the insertion tool and lugs for engagement with the cup rim. This segmentation allows the cap to provide robust attachment through multiple distributed engagement points (lugs with recesses) while maintaining flexibility for connection and disconnection. The segmented structure can accommodate the thin-walled cup geometry and provide stable engagement without requiring a complex monolithic attachment system.
Data Source
AI summary
A cap used during the insertion of an acetabular cup prosthesis. The cap includes impaction plate having an upperside and an underside. The impaction plate includes a plurality of separate sectors mutually connected at a connection point on the impaction plate by flanges. Each sector includes interlocking elements which in use enable the impaction plate to be connected to an introduction tool. The cap also includes at least one lug extending downwardly from the underside of each sector. The lug is located at the portion of the underside of the impaction plate which will in use enable the lug to be interconnected with a corresponding recess on an internal wall, an external wall or a rim of a prosthesis.