Adjustable Constraining Apparatus for Adaptive Bone Healing
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Solution Overview
Problem
Current constraint devices for anatomical structures, such as fractured bones and spinal segments, provide constant fixation forces that can hinder healing by stress shielding and limiting motion, leading to tissue necrosis and inadequate tissue remodeling, as they do not adjust forces over the healing process.
Innovation Solution
A constraining apparatus with a motion limiting member and a regulating member that adjusts the force resistance over time using bioabsorbable materials, compliance members, and damping elements, allowing for varying stiffness and damping properties to accommodate different phases of healing, and can be adjusted or automatically change properties based on tissue expansion or contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If constant fixation force is applied throughout healing, then initial stability is improved, but stress shielding occurs and tissue remodeling is hampered
Solution Approach 1:
The constraint device incorporates a compliance member that allows dynamic adjustment of fixation force throughout the healing process. The device transitions from rigid initial fixation to more compliant later-stage fixation, enabling the system to adapt its mechanical properties over time rather than maintaining constant rigidity
Solution Approach 2:
The device changes its mechanical parameters (stiffness, compliance) over time through the use of bioabsorbable materials and compliance members. The fixation force is not static but evolves during healing, with the compliance member allowing controlled deformation that reduces stress shielding while maintaining initial stability
2Stability of the object's composition
If constant fixation force is applied throughout healing, then initial stability is improved, but tissue necrosis may occur due to excessive compression
Solution Approach 1:
The compliance member enables dynamic reduction of compression force during healing. As the tissue heals and requires less support, the compliance member allows controlled motion that prevents excessive compression and associated tissue necrosis, while maintaining sufficient stability during critical early phases
3Stability of the object's composition
If rigid instrumentation is used for spinal stabilization, then segmental translation is prevented, but loading of fusion material is reduced
Solution Approach 1:
The device changes its stiffness parameter over time, providing high rigidity initially to prevent segmental translation and stabilize the fusion environment, then gradually reducing rigidity to allow loading of the fusion material. This temporal variation in mechanical properties resolves the contradiction between stability and loading requirements
4Stability of the object's composition
If static constraint device is used, then initial immobilization is improved, but motion is excessively limited throughout healing
Solution Approach 1:
The constraint device transitions from a static rigid constraint to a dynamic system with varying compliance. The compliance member allows controlled motion that adapts to healing stages, providing immobilization when needed while allowing progressive motion as tissue heals, thus resolving the contradiction between initial stability and ongoing adaptability
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 apparatus provides adjustable and adaptive fixation forces that reduce stress shielding, promote tissue repair by allowing micromotion, and minimize tissue necrosis, enabling effective healing by varying constraining forces and stiffness over time without the need for additional surgeries.
Implementation Method 1
A portion of the compliance member is encapsulated in a bioabsorbable material such that the compliance member is regulated by erosion of the bioabsorbable material
Implementation Method 2
a compliance member that provides a force resistant to relative movement of the first anatomical structure away from the second anatomical structure
Implementation Method 3
The constraining apparatus may also include a damper element that reduces relative motion between the first and second anatomical structures
Data Source
AI summary
A constraining apparatus includes a constraining structure that captures a first and a second anatomical structure. A motion limiting member coupled with the constraining structure is adapted to provide a force resistant to relative movement of the first anatomical structure away from the second anatomical structure. A regulating member is detachably coupled with the motion limiting member or the constraining structure and is adapted to change the resistant force provided by the motion limiting member when the regulating member is in direct engagement with the motion limiting member or constraining structure.