Modular Tibia Stem with Tension Compression Coupling
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Solution Overview
Problem
Current tibia stem components in total ankle replacement surgeries face challenges with pistoning or loosening, leading to long-term complications such as implant migration due to limited bone engagement and stability issues.
Innovation Solution
The development of modular stem components with specific geometries and surface texturing, including tapered connections and tensioning mechanisms, to enhance immediate stability and long-term fixation by engaging both cancellous and cortical tibia bone, allowing for adjustable length and secure coupling without threading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional tibia stem components are used, then the implant can be inserted into the bone, but pistoning or loosening occurs leading to implant migration over time
Solution Approach 1:
The tibia stem is divided into multiple modular components (first component, second component, third component) that can be coupled together. This segmentation allows each component to be optimized for specific functions: the first component engages cancellous bone, the second component provides the coupling interface, and the third component engages cortical bone, thereby improving overall implant stability and preventing pistoning or loosening over time
Solution Approach 2:
The coupling member is inserted through the second component and into the first and third components, creating a nested structure. The shaft portion of the coupling member is received within openings in the first and third components, while the head portion is received in the second component. This nesting arrangement secures all components together and prevents relative movement, eliminating pistoning issues
2Reliability
If modular stem components with tapered connections are used, then immediate implant stability is improved, but the device complexity increases
Solution Approach 1:
The first, second, and third components are pre-configured with specific geometries including tapered surfaces and openings of predetermined dimensions. The coupling member is pre-designed with a shaft portion and head portion that match these predetermined geometries. This preliminary configuration allows the components to be assembled together to form a stable modular stem construct, achieving immediate implant stability while managing device complexity through standardized interfaces
3Reliability
If the stem components are designed to engage both cancellous and cortical bone, then long-term migration is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
Different portions of the modular stem components have different geometries optimized for specific bone types. The first component has a geometry optimized for engaging cancellous bone, while the third component has a geometry optimized for engaging cortical bone. The second component has a geometry optimized for coupling with the coupling member. This local quality approach allows each component to be manufactured with precision tailored to its specific function, reducing overall manufacturing complexity while achieving reliable engagement with both bone types
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A prosthesis (100) may include a first component (102), a second component (120), and a coupling member (140). The first component may include a first body extending from a first end (104) to a second end (106), which may define a first opening (112) that extends inwardly toward the first end. The first opening may include a first portion (112a) having a first diameter and a second portion (112b) having a second diameter. The second component may include a second body extending from a first end (124) to a second end (126). The second body may define a second opening (132) that extends through the second body. The coupling member may be configured to couple the first component and the second component by compressing the first component and the second component. The coupling member may include a shaft portion (146) and a head portion (144). The shaft portion may be sized and configured to be received in the first opening and the second opening.