Multiaxial Tibia Stem Retraction Mechanism for Anti-Migration Fixation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Tibia stem components in total ankle arthroplasty face issues with pistoning and loosening due to limited bone engagement, leading to implant instability and migration over time.
Innovation Solution
The design of a tibia stem component with retractable members that can be controllably extended outward from the longitudinal axis to engage the intramedullary canal's surrounding bone, enhancing anchoring within the canal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tibia stem component uses a traditional fixed design, then the structure is simple and easy to manufacture, but the implant stability is insufficient and pistoning occurs
Solution Approach 1:
The tibia stem component incorporates retractable members that can dynamically change their configuration between retracted and extended positions. This dynamic feature allows the stem to adapt to different surgical conditions and bone densities, providing enhanced anchoring when needed while maintaining a compact profile during insertion, thereby resolving the contradiction between stability and structural simplicity.
Solution Approach 2:
The stem structure is divided into multiple independent retractable members that can be controlled individually or collectively. This segmentation allows for localized engagement with the intramedullary canal bone, providing targeted anchoring in specific regions while maintaining overall structural integrity, thus improving stability without requiring complete structural complexity throughout the entire stem.
2Reliability
If the retractable members are extended outward to engage bone, then anchoring is enhanced, but the device complexity increases
Solution Approach 1:
The retractable members are designed to be self-actuating through cam mechanisms that convert the axial insertion force into radial outward movement. This self-service mechanism eliminates the need for external actuators or complex control systems, allowing the stem to automatically engage the bone upon insertion while maintaining relative structural simplicity, thus resolving the contradiction between anchoring strength and mechanism complexity.
Solution Approach 2:
The cam mechanisms are pre-configured in the stem structure to automatically activate the retractable members during the insertion process. This preliminary action ensures that the anchoring engagement occurs seamlessly as part of the standard implantation procedure, without requiring additional steps or complex post-insertion activation mechanisms, thereby enhancing anchoring while controlling overall device complexity.
3Reliability
If the stem is designed for immediate stability, then implant migration is reduced, but the ease of operation during surgery decreases
Solution Approach 1:
The dynamic retractable members provide immediate stability upon insertion by automatically engaging the intramedullary canal bone, eliminating the need for separate stabilization steps. The surgical ease is maintained because this engagement occurs passively during the normal insertion process, requiring no additional surgical maneuvers or complex activation procedures, thus resolving the contradiction between immediate stability and ease of operation.
Data Source
AI summary
Provided are tibia stem components of ankle replacement prosthesis that are designed to engage dense tibia bone to reduce implant migration over long term.