Biodegradable Shape Memory Medical Device for Dynamic Bone Fixation
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Solution Overview
Problem
Current medical devices for bone fixation and osteotomy lack the ability to dynamically adjust their shape and tension in response to physiological conditions, which can lead to inadequate fixation or loosening, and often require manual operation, increasing the risk of infection and limited continuous movement in distraction osteogenesis.
Innovation Solution
A biodegradable medical device made from shape memory polymers that can change dimension and exert predetermined forces on healing tissues, activated by liquid stimuli, allowing for self-adjustment of tension and shape change, incorporating materials like polyglycolide, polylactides, and ceramic fibers, with mechanical and biochemical properties for enhanced tissue healing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a biodegradable medical device is made from conventional bioabsorbable materials, then the device can be absorbed by the body over time, but the device loses its mechanical strength and dimensional stability too quickly to maintain effective fixation throughout the healing period
Solution Approach 1:
The patent changes the material parameters by incorporating shape memory polymers that undergo phase transitions at specific temperatures. The device is programmed to maintain its mechanical properties and dimensional stability until a predetermined temperature is reached, at which point it undergoes a controlled phase transition to achieve dimensional change. This allows the device to maintain strength throughout the healing period while providing controlled dimensional changes when needed.
Solution Approach 2:
The patent uses composite materials combining shape memory polymers with traditional bioabsorbable materials. This composite structure allows the device to exhibit both the biodegradability of traditional materials and the controlled dimensional stability and shape-memory properties of shape memory polymers, resolving the contradiction between duration of action and strength retention.
2Strength
If a fixation device is made too tight to ensure stable fixation, then the initial fixation strength is improved, but the device cannot adapt to changes in tissue healing and may cause damage or loosening
Solution Approach 1:
The patent makes the fixation device dynamic by incorporating shape memory polymers that can change dimensions in response to temperature changes. The device is programmed to maintain its initial tight fixation to provide stable initial strength, then undergo controlled dimensional changes as the temperature reaches predetermined levels, allowing it to adapt to tissue healing changes while maintaining adaptability through controlled dimensional adjustment.
Solution Approach 2:
The device incorporates temperature-sensitive shape memory polymers that respond to the thermal environment as a feedback mechanism. As the body temperature and local thermal conditions change during healing, the device automatically adjusts its dimensions in response, providing feedback-driven adaptation without requiring external intervention.
3Adaptability or versatility
If a fixation device is made too loose to allow for tissue movement, then tissue healing flexibility is improved, but the fixation strength becomes insufficient to maintain proper alignment
Solution Approach 1:
The patent makes the device dynamic with shape memory polymers that can adjust dimensions based on temperature. The device starts with a loose configuration to allow tissue movement flexibility, then undergoes controlled dimensional changes at predetermined temperatures to increase fixation strength when needed, providing both flexibility and strength at different stages of healing.
4Ease of operation
If manual operation is used to adjust distraction osteogenesis devices, then the device can be operated and adjusted, but the risk of infection increases and continuous movement cannot be achieved
Solution Approach 1:
The patent makes the device self-operating by incorporating temperature-sensitive shape memory polymers that automatically adjust dimensions in response to thermal stimuli. The device eliminates the need for manual operation by using the body's thermal environment as a trigger for controlled dimensional changes, thereby reducing infection risk while maintaining operability through autonomous temperature-responsive adjustment.
Solution Approach 2:
The patent replaces the manual mechanical adjustment system with a temperature-driven shape memory polymer system. Instead of requiring external mechanical manipulation, the device uses thermal energy to trigger controlled dimensional changes, substituting a mechanical operation system with a thermally-actuated material response system.
5Stability of the object's composition
If the device maintains constant tension to ensure stable fixation, then the initial fixation stability is improved, but the device cannot compensate for changes in tissue healing and may become too tight or too loose
Solution Approach 1:
The patent makes the tension maintenance dynamic by incorporating shape memory polymers that adjust dimensions in response to temperature changes. The device maintains constant tension initially for stability, then automatically adjusts tension through controlled dimensional changes at predetermined temperatures, providing both stability and adaptability throughout the healing process.
Solution Approach 2:
The patent changes the tension parameter dynamically through temperature-triggered phase transitions in shape memory polymers. The device maintains constant tension during the initial healing phase, then undergoes controlled parameter changes when temperature reaches predetermined levels, allowing tension adjustment capability while maintaining stability during critical healing periods.
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
The device provides controlled, continuous movement and force in distraction osteogenesis, maintains predetermined tension for extended periods, and adjusts to ensure proper fixation, reducing the risk of infection and enhancing bone healing by adapting to physiological conditions.
Implementation Method 1
The shape memory polymeric material may be biodegradable or non-biodegradable. The polymeric material tends to assume its memory condition by activation of a polymer transition. The activation can occur e.g. by adsorption of liquid by the polymer
Implementation Method 2
The self-reinforced samples tended to keep a certain level of stress after 7 days testing period, whereas the not oriented samples had no significant residual stress left after 1 day
Data Source
AI summary
The invention relates to a biodegradable medical device which is made of at least one biodegradable material and has an initial shape and at least one evolved shape. The evolved shape is different from the initial shape, and the initial shape is adapted to change towards the evolved shape due to an external stimulus. The medical device has been loaded to have a predetermined tension level and the medical device is adapted to restore its tension to the predetermined tension level for at least 2 weeks in the physiological conditions, or conditions simulating the physiological conditions. The invention also relates to a method for manufacturing a biodegradable medical device.