3D-Printed Spinal Implant Porosity for Stable Bone Fusion
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Solution Overview
Problem
Conventional prosthetic implants for spinal fusion often fail to mimic bone density, leading to non-union and expulsion due to insufficient bone ingrowth, and lack optimal space for fusion, necessitating a solution that promotes bone integration and stability.
Innovation Solution
A spinal rod is manufactured using a molybdenum rhenium alloy through additive manufacturing processes, with specific geometric designs and surface features to promote bone ingrowth and fusion, including surface roughness, orifices, and channels to enhance integration with vertebral bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional prosthetic implants are used for spinal fusion, then the implant can be inserted between adjacent vertebrae, but the implant fails to mimic bone density sufficiently, leading to non-union and expulsion
Solution Approach 1:
The patent applies parameter changes by varying the density of the porous implant material to match bone density. The implant features a porous structure with controlled pore size and distribution, allowing it to mimic the mechanical properties of natural bone while facilitating bone ingrowth. This density matching prevents implant expulsion and promotes successful fusion.
Solution Approach 2:
The patent utilizes porous materials as the core structural feature of the implant. The porous architecture provides both mechanical support and pathways for bone ingrowth, enabling the implant to integrate with surrounding vertebral bone tissue. The porous structure allows bone cells to penetrate and colonize the implant, creating a strong biological bond that prevents expulsion.
2Strength
If conventional prosthetic implants are used, then the implant can provide structural support, but the implant does not allow optimal space for bone ingrowth
Solution Approach 1:
The implant employs a porous structure that creates interconnected void spaces throughout its volume. These pores provide channels for bone cells to migrate into and along the implant, facilitating extensive bone ingrowth. The porous architecture maintains structural integrity while maximizing the volume available for biological integration.
Solution Approach 2:
The patent applies dimensionality change by creating a three-dimensional porous network within the implant structure. This multi-dimensional pore system allows bone ingrowth to occur throughout the entire volume of the implant, not just at the surface. The 3D porous architecture provides pathways in multiple directions, enhancing bone integration while maintaining mechanical strength.
3Ease of operation
If conventional prosthetic implants are used, then the implant can be inserted between vertebrae, but the implant does not provide sufficient stability, causing dislodgement or movement from desired location
Solution Approach 1:
The porous structure of the implant enables bone cells to penetrate deep into the implant material, creating a strong biological anchor. As bone grows into the porous structure, it forms a mechanical interlock that firmly secures the implant in place. This biological fixation prevents dislodgement and movement, providing long-term stability while maintaining ease of initial insertion.
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 solution provides a robust spinal implant that facilitates optimal bone ingrowth, reduces the risk of expulsion, and ensures stable fusion by mimicking bone density and structure, enhancing the integration with vertebral bodies.
Implementation Method 1
forming at least part of the spinal rod using an additive manufacturing process, the process comprising: selecting a molybdenum rhenium alloy consisting of 52% to 70% molybdenum and 30% to 48% rhenium, the molybdenum rhenium alloy being used to form the at least part of the spinal rod; and curing a plurality of layers of the selected molybdenum rhenium alloy to form the at least part of the spinal rod having the required geometric shape
Data Source
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Figure 5A~5B
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AI summary
In some embodiments, a spinal implant (10, 110, 210, 310, 400) is provided and includes a body portion defining a longitudinal axis. The body portion includes a distal end portion, a proximal end portion, opposed side surfaces that extend between the distal and proximal end portions, and top and bottom surfaces configured and adapted to engage vertebral bodies. The top and bottom surfaces have a surface roughness between 3-4 μm. A cavity extends through the top and bottom surfaces defining a surface area that is at least 25% of a surface area of the top surface or the bottom surface. First orifices (24, 124, 224, 324, 426a) are defined through the top surface and second orifices (34, 134, 234, 334, 426b) are defined through the bottom surface. The second orifices are connected to the first orifices by a plurality of channels.