Controlling Nitinol Unloading Stress for Orthopedic Bone Compression
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Solution Overview
Problem
Existing orthopedic devices, such as screws, staples, plates, and intramedullary devices, often fail to maintain sufficient compressive load between bone fragments for prolonged periods, leading to non-unions, mal-unions, and delayed unions due to rapid dissipation of compressive force as bone relaxes and remodels, and Nitinol devices may exert excessive recoverable strain damaging bone tissue.
Innovation Solution
The development of devices that control the unloading stress and recoverable strain of Nitinol and other shape memory material devices, allowing surgeons to adjust the compression and strain levels by using internal retaining pins or delivery mechanisms, enabling controlled application and maintenance of compressive loads without damaging bone tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If Nitinol devices are used to generate compressive load between bone fragments, then the compressive force is improved, but the recoverable strain may be excessive and damage bone tissue
Solution Approach 1:
The patent employs a dynamic adjustment mechanism that allows the compressive force to be controlled and modified after implantation. The device transitions from a static force application system to a dynamic one where the recoverable strain can be adjusted within a range, enabling the compressive load to be optimized as bone healing progresses and preventing excessive force that could damage bone tissue.
Solution Approach 2:
The patent changes the physical parameters of the Nitinol device by allowing adjustment of the recoverable strain parameter. This enables control over the magnitude of compressive force generated, transforming it from a fixed parameter determined solely by manufacturing to a可调 parameter that can be optimized post-implantation to prevent bone tissue damage while maintaining effective compression.
2Force
If conventional devices are used to generate compressive load, then the initial compression is achieved, but the compressive force dissipates rapidly as bone relaxes and remodels
Solution Approach 1:
The patent creates a dynamic system where the compressive force can be adjusted in response to bone relaxation and remodeling. As the bone heals and changes shape, the device can be adjusted to maintain optimal compressive force, preventing the rapid dissipation that occurs with conventional static devices.
Solution Approach 2:
The device is designed to work in conjunction with the natural bone healing process, where the adjustable nature of the compressive force allows it to adapt to the changing mechanical environment as bone relaxes and remodels, effectively serving itself by maintaining force without requiring external intervention for force application.
3Reliability
If the compressive load is increased to ensure bone fragments remain in close contact, then the healing outcome is improved, but the risk of damaging bone tissue increases
Solution Approach 1:
The patent implements a dynamic force adjustment system that allows the compressive load to be optimized for reliable healing outcomes. The ability to adjust the recoverable strain enables the force to be increased sufficiently to ensure bone fragments remain in close contact for healing, while preventing excessive force that could damage bone tissue, thus resolving the reliability-harmfulness contradiction.
4Force
If Nitinol devices with high recoverable strain are used, then the compressive force generation is improved, but the control over compression levels is reduced
Solution Approach 1:
The patent transforms the device from a static system with fixed compressive force to a dynamic system where the recoverable strain and resulting compressive load can be adjusted. This dynamic capability provides surgeons with control over compression levels while maintaining the high force generation capability of Nitinol, resolving the contradiction between force generation and controllability.
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 enable controlled application and maintenance of compressive loads between bone fragments, facilitating optimal healing by allowing surgeons to adjust the compression and strain levels, thereby reducing the risk of non-unions and mal-unions and improving bone healing outcomes.
Implementation Method 1
Nitinol can be used to improve the functional performance of these devices by utilizing either the shape memory effect of Nitinol or the superelastic properties of Nitinol
Implementation Method 2
Nitinol can be used to improve the functional performance of these devices by utilizing either the shape memory effect of Nitinol or the superelastic properties of Nitinol
Data Source
AI summary
This disclosure provides novel devices for controlling the unloading stress and recoverable strain of Nitinol devices and/or other shape memory material devices. The devices may be used to bring bone fragments into close proximity with each other, generate a compressive load between the bone fragments, and maintain that compressive load between the bone fragments while healing occurs.