Bone Anchor Device Using Shape Memory Alloy Pivot
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Solution Overview
Problem
Current bone anchor technologies face challenges in accurately and efficiently joining or fusing bone pieces under compression, particularly in small bone structures like the phalangeal bones of the human foot, due to issues with strain distribution and deployment mechanisms that can cause misalignment and movement during the deployment process.
Innovation Solution
The use of shape memory alloys with super-elastic properties in bone anchor devices, which include a central portion with pivot points and actuation mechanisms that allow for controlled strain release to rotate anchor elements, ensuring precise alignment and deployment of bone anchor elements within the bone pieces, utilizing a deployment pin mechanism that balances forces to maintain accurate placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bone anchor deployment mechanisms are used, then bone pieces can be joined, but misalignment and movement occur during deployment due to strain distribution issues
Solution Approach 1:
The patent changes the physical state and mechanical properties of the material by using shape memory alloys that undergo phase transformation between martensite and austenite. This parameter change allows the central portion to transition from a soft, easily deformable state during insertion to a rigid, strain-retaining state during deployment, ensuring precise alignment control.
Solution Approach 2:
The bone anchor device utilizes composite material properties by combining shape memory alloy characteristics (super-elasticity, phase transformation) with traditional surgical implant requirements. The central portion's unique material behavior enables it to function as both a flexible insertion component and a rigid deployment mechanism, resolving the alignment-stability contradiction.
2Reliability
If shape memory alloys are used in the central portion, then strain can be retained for controlled deployment, but the device complexity increases
Solution Approach 1:
The shape memory alloy central portion serves multiple functions automatically without external intervention: it retains strain during insertion, maintains alignment, and provides controlled deployment force. The material's inherent phase transformation properties enable it to self-regulate its mechanical behavior based on temperature and stress conditions, reducing the need for additional control mechanisms.
Solution Approach 2:
The central portion made of shape memory alloy performs multiple functions: it acts as the structural core, the strain retention mechanism, the alignment guide, and the deployment actuator. This multi-functionality reduces overall device complexity by eliminating the need for separate components for each function.
3Ease of operation
If the central portion is made soft for easy insertion, then insertion is facilitated, but deployment control is lost
Solution Approach 1:
The central portion's mechanical properties are made dynamic through the shape memory effect. During insertion, the material behaves in a soft, compliant manner that facilitates easy passage through bone tissue. Upon deployment when temperature or stress conditions change, it transitions to a rigid state that provides precise control and retains strain for accurate anchor element positioning.
Solution Approach 2:
The patent exploits the phase transition between martensite (soft, easily deformable) and austenite (rigid, strain-retaining) phases of the shape memory alloy. This phase transition enables the central portion to automatically adjust its mechanical properties: soft during insertion for ease of operation, then rigid during deployment for precise control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables precise and efficient deployment of bone anchor devices, minimizing misalignment and movement during surgery, and effectively fusing bone pieces by utilizing the super-elastic properties of shape memory alloys to apply and release strain, ensuring stable bone fixation.
Implementation Method 1
The central portion includes a shape memory alloy actuator made of a shape memory alloy with a selected austenitic finish temperature of the shape memory alloy selected such that the martensitic crystalline phases of the shape memory alloy are unstable at room temperature or far below body temperature
Implementation Method 2
Embodiments using shape memory alloys may use super-elastic properties of shape memory alloys to provide forces and deflections that actuate bone anchoring element(s) within bones
Data Source
AI summary
Provided herein are bone anchor devices including embodiments using adaptive materials, including shape memory materials such as shape memory alloys. Embodiments using shape memory alloys may use super-elastic properties of shape memory alloys to provide forces and deflections that actuate bone anchoring element(s) within bones. Embodiments of bone anchoring elements may be created that actuate with respect to one or more pivot point(s), with the bone anchoring elements on an opposite side of the pivot point from the actuating member composed of, for example, shape memory material. The pivot point(s) of a bone anchor device may be positioned in a central portion of the bone anchor device. The central portion of the bone anchor device may span between two pieces of bone or two separate bones (e.g., two bones of a joint) into which bone anchoring elements may be embedded and fixed.