Shape-Memory Intramedullary Compression for Bone Healing Stability
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Solution Overview
Problem
Existing intramedullary devices fail to consistently bring bone fragments into close proximity, generate and maintain compressive loads effectively for prolonged periods during healing, and provide insufficient torsional stability.
Innovation Solution
Intramedullary devices made of shape memory materials like Nitinol or PEEK, featuring differential thread pitches, mirrored thread geometries, and reversible elongation or deformation mechanisms to enhance compression and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If traditional intramedullary devices with coplanar legs are used, then the device can be inserted into the intramedullary canal, but the compressive load dissipates rapidly as the bone relaxes and remodels
Solution Approach 1:
The intramedullary device incorporates a non-coplanar leg configuration that dynamically adapts to bone relaxation and remodeling during the healing process. The legs are positioned at different angles and planes, allowing the device to maintain compressive force as the bone changes shape during healing, rather than losing compression as traditional fixed coplanar leg devices do.
Solution Approach 2:
The device utilizes shape memory materials that change their physical parameters in response to temperature or stress changes. This allows the device to adjust its compression force dynamically during the healing process, maintaining optimal compressive load even as the bone relaxes and remodels over time.
2Stability of the object's composition
If traditional intramedullary devices with coplanar legs are used, then the device structure is simple, but the device provides insufficient torsional stability to the fusion site
Solution Approach 1:
The device employs non-coplanar legs arranged in an asymmetric configuration rather than symmetric coplanar positioning. This asymmetric arrangement creates multiple planes of resistance to torsional forces, significantly improving rotational stability at the fusion site while maintaining a relatively simple overall device structure.
Solution Approach 2:
The legs are positioned in three-dimensional space rather than confined to a single plane, adding dimensional complexity to the force distribution. This spatial arrangement allows the device to resist torsional loads more effectively by distributing forces across multiple planes, enhancing stability without requiring a substantially more complex device architecture.
3Force
If traditional intramedullary devices are used, then the device can grip the bone wall, but the device does not always succeed in bringing bone fragments into close contact
Solution Approach 1:
The device applies compression forces at multiple localized points through its non-coplanar leg configuration, ensuring that bone fragments are brought into close contact at each grip point. This distributed local compression approach ensures uniform approximation of bone surfaces, preventing gaps that would occur with single-point or coplanar compression methods.
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
These devices effectively maintain bone fragment proximity and compressive loads, enhancing healing by providing superior compression holding capabilities and torsional stability.
Implementation Method 1
Intramedullary devices made of shape memory materials like Nitinol or PEEK, featuring differential thread pitches, mirrored thread geometries, and reversible elongation or deformation mechanisms to enhance compression and stability
Data Source
AI summary
This disclosure describes exemplary screw and intramedullary devices that are better able to bring bone fragments into close proximity with each other, generate a compressive load, and maintain that compressive load for a prolonged period of time while healing occurs. The devices are made of a shape memory material.