Shape-Changing Bone Implant for Gap Closure and Healing
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Solution Overview
Problem
Existing rigid bone fixation implants often fail to promote effective healing due to gaps between bone segments, soft tissue infiltration, and inadequate mechanical loading, leading to delayed or non-healing fractures and joint fusions.
Innovation Solution
Development of shape-changing bone implants that store mechanical energy and change shape to actively pull and compress bone segments together, maintaining constant contact and applying pressure to enhance healing, while also acting as a scaffold for bone formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If rigid bone fixation implants are used to hold bone segments in place, then the bone segments are stabilized for healing, but gaps form between bone edges due to inflammation-mediated bone resorption and surgical reduction difficulties, delaying healing
Solution Approach 1:
The implant transitions from a rigid static structure to a dynamic shape-changing structure that can actively close gaps between bone edges. The implant undergoes a shape change after implantation to pull bone edges together and maintain contact, adapting to the healing process rather than remaining fixed in the initial configuration.
Solution Approach 2:
The implant is designed with pre-stored mechanical energy in a strained state before implantation. This preliminary stored energy is released after implantation to actively pull bone edges together, preventing gap formation before it occurs rather than correcting it afterward.
2Strength
If rigid bone implants are used to fixate bone segments, then mechanical support is provided, but soft tissue infiltrates the space between healing bones, blocking bone fusion
Solution Approach 1:
The dynamic shape-changing capability allows the implant to actively close gaps and maintain bone edge contact throughout the healing process. This continuous contact prevents soft tissue from infiltrating between bone surfaces, eliminating the pathway for harmful tissue intrusion while maintaining mechanical support.
3Reliability
If shape-changing bone implants are used to actively pull and compress bone segments together, then bone healing is enhanced by maintaining constant contact and applying pressure, but the device complexity increases compared to rigid implants
Solution Approach 1:
The implant utilizes changes in material parameters (shape, volume, density) through phase transformation or elastic deformation. By changing physical parameters rather than adding mechanical components, the implant achieves complex functions with relatively simple structure. The material itself performs the work of closing gaps and maintaining compression through its inherent shape memory or elastic properties.
Solution Approach 2:
The implant is designed to automatically perform the healing-enhancing functions without requiring external actuation or complex control mechanisms. The stored mechanical energy and material properties enable the implant to self-activate and maintain bone compression autonomously throughout the healing process, reducing device complexity while ensuring reliable healing promotion.
4Stability of the object's composition
If bone segments are held apart by rigid implants, then alignment is maintained, but mechanical loading is inadequate to stimulate bone density and growth
Solution Approach 1:
The dynamic shape-changing implant actively applies mechanical loading to bone segments during the healing process. As the implant changes shape and maintains bone edge contact, it creates controlled mechanical stress and strain that stimulates bone density and growth. This dynamic mechanical stimulation is superimposed on the alignment function, providing both stability and biological activation.
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 shape-changing implants significantly improve bone healing by closing gaps, blocking soft tissue infiltration, and stimulating bone density and growth through mechanical loading and electrical current flow, resulting in quicker and more effective bone fusion without the formation of calluses.
Implementation Method 1
The shape changing implant uses its material properties and mechanisms to store recoverable mechanical energy in its structure or mechanism and change shape to pull together and compress the bone fixation interface
Implementation Method 2
The implants change shape through their metallurgic (or polymeric) properties and mechanisms
Implementation Method 3
The implants change shape through their metallurgic (or polymeric) properties and mechanisms
Implementation Method 4
stimulating bone density and growth through mechanical loading and electrical current flow
Data Source
AI summary
Described is a new bone healing method and class of bone fixation implants that change shape once implanted so as to minimize non-healing and speed the bone healing process. The bone fixation method involves shape changing implants that continuously hold the bones in apposition so that a gap does not form. Gaps in time allow non-bony tissue to infiltrate and stop healing. Furthermore, the implants actively compress bone to increase bone mass and strength. Bone cell pressure due to compression and electrical current flow due to bone deformation act to stimulate healing. The new implant designs also provide a scaffolding to conduct bone through the implant and across the healing bone interface. The methods and designs are applicable to but not limited to use for bone screws, plates, staples, rods, cylinders and external fixation devices.