Pivoting Shim for Knee Prosthesis Trial Alignment
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Solution Overview
Problem
Current orthopaedic surgical instruments for knee prosthesis implantation lack efficient methods for accurately sizing and selecting prosthetic components, leading to instability and misalignment during joint arthroplasty procedures.
Innovation Solution
The development of an orthopaedic surgical instrument system featuring a tibial bearing trial assembly with a shim that can pivot or be locked, allowing for precise adjustment and selection of tibial bearing surface trial components, coupled with a keel punch for preparing the tibia, to ensure proper alignment and sizing of prosthetic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed orientation shim is used, then the tibial bearing trial assembly is stable and prevents rotation, but it cannot accommodate different bearing surface orientations needed for accurate component sizing
Solution Approach 1:
The shim is designed with a slot and lug mechanism that allows it to be positioned in multiple discrete orientations (first orientation with slot, second orientation without slot) relative to the central post. This dynamic reconfigurability enables the assembly to adapt between different bearing surface orientations while maintaining stability in each configured state, resolving the contradiction between adaptability and stability.
2Measurement precision
If multiple trial components are used for different bearing surfaces, then component sizing accuracy is improved, but the complexity of the surgical instrument system increases
Solution Approach 1:
The shim serves multiple functions: it connects the central post to the bearing surface trial component, provides rotational positioning capability, and enables different bearing surface orientations. By making the shim multi-functional rather than requiring separate components for each function, the system achieves high measurement precision while controlling overall complexity.
Solution Approach 2:
The trial assembly is segmented into modular components (central post, shim, bearing surface trial component) that can be independently selected and assembled. This segmentation allows the surgeon to assemble the appropriate configuration for each specific sizing requirement without needing completely separate trial assemblies, balancing precision needs with system complexity.
3Manufacturing precision
If the tibial bearing trial assembly is prevented from rotating, then alignment accuracy is improved, but it cannot facilitate the pivoting motion needed to test different component configurations
Solution Approach 1:
The slot-and-lug mechanism on the shim provides conditional rotational freedom: the assembly can pivot when the lug engages the slot for testing different configurations, and becomes rotationally locked when the lug engages the flat surface for precise alignment. This dynamic behavior resolves the contradiction between needing rotation for testing and preventing rotation for alignment.
Data Source
AI summary
An orthopaedic surgical instrument system that includes an orthopaedic surgical instrument adapted to be positioned on a proximal end of a patient's tibia, and a tibial bearing trial assembly configured to be coupled to the orthopaedic surgical instrument. The tibial bearing trial assembly includes a plurality of tibial bearing surface trial components and at least one shim.