Morphable Bone Fixation Device with Reinforcement
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Solution Overview
Problem
Screw implants face complications such as screw misplacement, fracture, bone fracture, loosening, and pullout, particularly in osteoporotic bones and those with low bone mineral density, due to anatomical constraints and limited dexterity of traditional drilling instruments.
Innovation Solution
A bone fixation device comprising a continuum morphable hollow shell structure with a screw thread and reinforcement wires, along with a castable filler material, is used, allowing for customizable implantation trajectories and material properties to enhance fixation in high-density bone regions, fabricated using 3D printing and steerable drilling robots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional rigid drilling instruments and screws are used, then the implantation process is simple, but the ability to navigate anatomical constraints and achieve precise placement is limited
Solution Approach 1:
The patent employs a continuum morphable hollow shell structure that can dynamically change its configuration during implantation. The shell transitions from a compressed delivery state to an expanded functional state within the bone, allowing it to adapt to complex anatomical trajectories while maintaining precise placement capability
Solution Approach 2:
The hollow shell structure is designed as a flexible, morphable component that can be compressed for delivery through narrow anatomical passages and then expanded to its functional shape within the bone. This flexible shell enables navigation through complex 3D trajectories while maintaining structural integrity and placement precision
2Reliability
If linear implantation trajectories are used, then the implantation process is straightforward, but the ability to avoid low BMD regions and nerves is compromised
Solution Approach 1:
The patent transitions from traditional linear 1D implantation trajectories to complex 3D curved trajectories. The morphable shell structure enables navigation through three-dimensional space, allowing the implant to follow optimal paths that avoid low BMD regions and neural structures while anchoring in high-density bone areas for improved fixation reliability
Solution Approach 2:
The hollow shell structure is designed with curved, morphable geometry that can follow non-linear trajectories within the bone. This curvature capability allows the implant to navigate around anatomical obstacles and follow optimal stress distribution paths, improving fixation reliability while maintaining ease of deployment through the delivery system
3Adaptability or versatility
If a fixed stiffness implant is used, then the device structure is simple, but the ability to adapt to different bone mineral densities is limited
Solution Approach 1:
The patent employs a composite structure where the hollow shell and internal filler material can be customized with different material properties and stiffness characteristics. This local quality variation allows the implant to be tailored to match specific bone mineral density conditions, providing optimal adaptability while maintaining a relatively simple overall device architecture
Solution Approach 2:
The implant combines a hollow shell structure with an internal filler material, creating a composite device where each component can be optimized for specific mechanical properties. This composite approach enables customization of stiffness and mechanical behavior to adapt to different bone densities without significantly increasing device structural complexity
4Stability of the object's composition
If the hollow shell structure is expanded in vivo, then the fixation stability is improved, but the implantation procedure becomes more complex
Solution Approach 1:
The hollow shell structure is pre-compressed into a compact delivery configuration that facilitates easy insertion through the bone. Once in place, the shell is then expanded to its functional size to achieve optimal fixation stability. This preliminary compression action simplifies the implantation procedure while maintaining the stability benefits of the expanded structure
Data Source
AI summary
A bone fixation device comprises a continuum morphable hollow shell structure including a proximal end and a distal end, an implantation head at the proximal end and a screw thread positioned external to the shell structure between the implantation head and a screw tip positioned at the distal end. A bone fixation system comprises a bone fixation device as described above, at least one reinforcement wire configured for insertion into the bone fixation device, and a castable filler material configured for insertion into the bone fixation device. A bone fixation method comprises fabricating a bone fixation device as described above, drilling the implantation trajectory, implanting the bone fixation device, implanting at least one reinforcement wire within the bone fixation device, and injecting the bone fixation device with a castable filler material via an aperture of the bone fixation device.