Controlled randomized porous structures and methods for making same
Inventors
Landon, Ryan L. • Agnihotri, Aashiish • Gilmour, Laura J. • Sharp, Jeffrey • Winebarger, Randy C.
Assignees
Publication Number
US-12285547-B2
Publication Date
2025-04-29
Expiration Date
2030-11-12
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Abstract
Improved randomized porous structures and methods of manufacturing such porous structures are disclosed. The scaffold of the porous structures are formed from by dividing the space between a plurality of spatial coordinates of a defined volume, where the plurality of spatial coordinates have been moved in a random direction and a random finite distance according to a predetermined randomization limit.
Core Innovation
The invention relates to improved randomized porous structures and manufacturing methods for such structures, particularly suitable for medical implants. The central innovation involves forming a scaffold by dividing the space between a plurality of spatial coordinates within a defined volume, where these coordinates have been randomly shifted in direction and distance according to a predetermined randomization limit. The result is a controlled, yet random arrangement of struts and nodes within the structure, closely resembling trabecular bone features for enhanced physiological compatibility.
The problem addressed by this invention is that conventional fabrication methods for porous structures, such as those used in orthopedic implants, trade off porosity for strength, often resulting in weak areas at the strut intersections and lacking the randomness of natural bone. Prior art methods for randomizing these structures are limited, tend to introduce structural weaknesses, or are inefficient and costly. Furthermore, conventional structures do not provide the seamless integration or customization needed for optimal implant performance.
The invention provides methods for defining and perturbing inner and outer seed points within geometric volumes, limiting their random movement to prevent overlap and ensure compatibility between adjacent tiles or volumes. Tessellation, such as Voronoi tessellation, is applied to these randomized points to define struts and nodes, allowing seamless joining of multiple volumes. The model is then fabricated using free-form or rapid manufacturing techniques such as direct metal fabrication, resulting in biocompatible, strong, and porous scaffolds with customizable shape, porosity, pore size, and strength.
Claims Coverage
The independent claim covers a computer-aided process for creating customizable, randomized porous structures through defined base volumes, controlled spatial randomization, and tessellation-based strut definition integrated with layer-by-layer additive fabrication.
Computer-aided process for creating a porous structure from stacked or tiled base volumes of randomized struts
A process wherein a model of the porous structure is created by defining one or more stacked or tiled base volumes, each composed of randomized struts with elongated bodies and nodes at each end, the struts being connected at nodes. The model is converted to a format compatible with a computer-aided apparatus, provided to the apparatus, and fabricated by iterative deposition and energy-induced fusing, melting, or sintering of material layers to produce a cross-section in accordance with the model.
Randomization of strut location and size by tessellation of perturbed seed points
The model's randomized strut network is generated by dividing each base volume into multiple three-dimensional cells, using a tessellation process (such as Voronoi tessellation) applied to a plurality of seed points that have been randomly perturbed in location. The edges of the cells define the strut locations, and vertices define the end nodes of the struts, ensuring controlled randomization and structural uniqueness.
In summary, the inventive features provide a process for designing and fabricating porous structures with controlled, randomized strut networks by tiling and tessellation of randomized seed points, supporting seamless integration and additive manufacturing.
Stated Advantages
Provides porous biocompatible structures with improved strength for weight bearing, porosity for tissue in-growth, and enhanced connectivity to resemble trabecular bone.
Promotes bone tissue and soft tissue in-growth due to the controlled, yet random scaffold arrangement.
Enables efficient methods for fabricating customized porous structures tailored to application needs, such as specific patient requirements for distribution, pore size, porosity, and strength.
Offers seamless fit and interface between joined structures, regardless of whether they are identical or not.
Allows for time- and cost-effective fabrication of complex porous structures using negative space manipulation.
Reduces the need for thicker struts to achieve strength, maintaining higher porosity without compromising mechanical integrity.
Improves resistance to stress, vibration, and fracture by eliminating weak planes present in uniform, regular structures.
Documented Applications
Medical implants, including orthopedic implants such as hip, knee, ankle, dental, shoulder, foot/hand, flanges, spine, skull plates, fracture plates, intramedullary rods, augments, staples, bone screws, and small joint implants.
Cardiovascular implants, including heart valves and artificial heart and ventricular assist devices.
Ligament and muscle fasteners.
Filters requiring controlled porosity.
Heat sinks, cushions, wound dressings, cartilage or fat pad substitutes, instrument weight reduction material, rasps, tissue sampling structures, and debridement burrs.
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