Composite Trial Prosthesis Shim Marking Visibility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing composite trial tibial inserts for knee replacement procedures require careful marking to prevent incorrect recording of thickness and shape, which can be difficult due to the thin nature of shims and visibility issues during joint reduction.
Innovation Solution
A composite trial prosthesis design where a first component has markings obscured by a shim, with the shim having visible markings indicating the composite thickness, reducing the risk of incorrect recording and improving visibility during surgical procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a full range of trial tibial inserts with different thicknesses are provided for every size and shape of bearing surface, then all possible combinations can be accommodated, but the number of required trial inserts increases significantly
Solution Approach 1:
The trial insert system is segmented into two independent components: a bearing component (providing size and shape) and a shim (providing thickness variation). This allows the thickness function to be separated from the bearing surface function, reducing the total number of components needed while maintaining full combinatorial coverage.
Solution Approach 2:
The bearing component is designed to be universal and can be combined with multiple different shims of varying thicknesses. This multi-functionality allows a single bearing component to work with the entire range of shim thicknesses, eliminating the need for dedicated trial inserts for each thickness variation.
2Loss of information
If markings are placed on both the bearing component and shims to indicate thickness, then thickness information is available, but the risk of incorrect recording increases due to visible markings on both components
Solution Approach 1:
The thickness indication function is extracted from the bearing component and placed exclusively on the shim. By removing the thickness marking from the bearing component, the source of confusion is eliminated, and only the shim provides thickness information, ensuring accurate recording.
3Manufacturing precision
If shims are made as thin sheets to provide precise thickness adjustments, then accurate thickness control is achieved, but visibility of markings on the shim becomes difficult during joint reduction
Solution Approach 1:
The marking visibility problem is solved by extending the marking onto the tab that protrudes from the shim plane. This dimensional extension allows the marking to be viewed from above (anterior of the joint) rather than requiring viewing from the side, making thin shim markings easily visible during joint reduction.
4Reliability
If a tab is added to the shim to extend over the bearing component and obscure markings, then incorrect recording is prevented, but the device complexity increases
Solution Approach 1:
The tab is designed as a multi-functional feature that simultaneously provides marking visibility extension and automatic obscuration of the bearing component markings. This single structural element performs multiple protective and informative functions, minimizing the actual increase in complexity while maximizing reliability.
Data Source
AI summary
A composite trial prosthesis comprises a first component (2) and a shim (4). The first component (2) has a first surface (8) corresponding to a surface of a prosthetic component and a reverse surface (10). The shim (4) is arranged to couple to the reverse surface (10). The first component (2) further comprises a first marking (24) which is arranged to be visible when the first component (2) is coupled directly to a bone or a further prosthetic component. Part of the shim (26) is arranged to obscure the first marking (24) when the shim (4) is coupled to the reverse surface (10), the shim (4) further comprising a second marking (28) which is visible when the shim (4) is coupled to a bone or a further prosthetic component. A set of composite trial prostheses and a method of selecting a required surgical prosthesis are also disclosed.