Sternal Anchor Assembly with Ratcheting Lock for Multi-Directional Fixation
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Solution Overview
Problem
Current methods for closing a sternotomy, such as wire cerclages and rigid bone plates, are either ineffective in limiting all types of sternal movement or are costly and time-consuming to implement.
Innovation Solution
An anchor assembly is used to secure the sternal halves, featuring an anchor insertable into a bone tunnel and cerclage elements that are locked to the anchor using a ratcheting lock, thereby limiting movement in multiple directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire cerclages are used to close the sternum, then the procedure is simple and cost-effective, but the wire cerclages are less effective at limiting relative movement of the sternal halves in all directions
Solution Approach 1:
The fixation device is divided into multiple independent components: a first fixation element engaging the first sternal half and a second fixation element engaging the second sternal half. These segmented elements can independently limit movement in different directions, providing comprehensive stabilization without requiring a single complex structure.
Solution Approach 2:
A compression member acts as an intermediary element that bridges the two sternal halves and engages with both fixation elements. This intermediary component transmits compressive forces to limit relative movement while simplifying the overall assembly process compared to direct rigid plate fixation.
2Reliability
If rigid bone plates are used to secure the sternal halves, then all types of sternal movement are limited effectively, but the procedure is costly and time-consuming
Solution Approach 1:
The fixation device is divided into multiple independent components: a first fixation element engaging the first sternal half and a second fixation element engaging the second sternal half. These segmented elements can independently limit movement in different directions, providing comprehensive stabilization without requiring a single complex structure.
Solution Approach 2:
The fixation elements incorporate movable or adjustable components that allow dynamic adaptation to the sternal anatomy during insertion. The compression member can be adjusted to apply optimal compressive force, enabling the device to achieve rigid plate-level stabilization with simpler, more rapid installation procedures.
3Reliability
If rigid bone plates are used to secure the sternal halves, then all types of sternal movement are limited effectively, but the procedure is costly
Solution Approach 1:
Each fixation element is designed with localized engagement features that specifically target particular regions of the sternal halves. The first fixation element engages the first sternal half with specific geometric features, while the second fixation element engages the second sternal half with corresponding features, providing targeted stabilization without the need for expensive comprehensive rigid plate systems.
Solution Approach 2:
The fixation device utilizes simpler, more cost-effective materials and designs compared to traditional rigid bone plates. The fixation elements and compression member can be manufactured from cheaper materials while maintaining sufficient mechanical properties for the application, reducing overall procedure cost while achieving the required stabilization effect.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
An anchor assembly (100), for securing a first portion and a second portion of a separated sternum, can include a lock (118), an anchor (102), and a cerclage (104). The anchor can include a body (112) locatable between the first portion and the second portion of the sternum, where the body can define an end portion. The anchor can include a collar (114) connected to the body and extending outward from the end portion of the body. The collar can engage an outer surface of the sternum to limit movement of the body beyond the outer surface of the sternum. The cerclage can be connected to and can extend from the anchor. The cerclage can be configured to at least partially surround the first portion and the second portion of the separated sternum.