Controlled randomized porous structures and methods for making same

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.

1 . A porous three-dimensional structure arranged and configured to be implanted in a body, the porous three-dimensional structure comprising:
 a plurality of connected cells, each cell comprising a plurality of struts and a plurality of nodes, wherein the porous three-dimensional structure includes:   at least one first cell comprising the plurality of struts and the plurality of nodes, and a plurality of second cells positioned within the at least one first cell, the second cells formed out of a plurality of struts coupled with one of the plurality of nodes associated with the first cell.   
     
     
         2 . The porous three-dimensional structure of  claim 1 , wherein each second cell includes an internal volume that is substantially equal to an internal volumes of the other second cells. 
     
     
         3 . The porous three-dimensional structure of  claim 1 , wherein the porous three-dimensional structure includes a porosity between about 60% and about 85%. 
     
     
         4 . The porous three-dimensional structure of  claim 1 , wherein the at least one first cell includes a polyhedron with four or more faces. 
     
     
         5 . The porous three-dimensional structure of  claim 1 , wherein at least one of the plurality of second cells include a polyhedron with four or more faces. 
     
     
         6 . The porous three-dimensional structure of  claim 5 , wherein at least one of the four or more faces of the polyhedron comprises a portion of a first cell of the at least one first cell. 
     
     
         7 . The porous three-dimensional structure of  claim 1 , wherein each of the at least one first cells comprise a first polyhedron with a first number of faces and each of the plurality of second cells comprise a second polyhedron with a second number of faces. 
     
     
         8 . The porous three-dimensional structure of  claim 7 , wherein the first number of faces equals the second number of faces. 
     
     
         9 . The porous three-dimensional structure of  claim 1 , wherein the plurality of struts and the plurality of nodes are formed from a powdered metal that is melted or sintered in a plurality of layers. 
     
     
         10 . A porous structure for implantation in a body of a patient, the porous structure comprising:
 a unit cell with an outer boundary and an interior volume, the outer boundary comprising a first geometric structure defined by a set of boundary struts and the interior volume comprising a second geometric structure within the outer boundary, the second geometric structure defined by a set of internal struts and at least one boundary strut in the set of boundary struts.   
     
     
         11 . The porous structure of  claim 10 , comprising a porosity between about 60% and about 85%. 
     
     
         12 . The porous structure of  claim 10 , wherein a shape of the first geometric structure is different than a shape of the second geometric structure. 
     
     
         13 . The porous structure of  claim 10 , wherein the first geometric structure includes a polyhedron with four or more faces. 
     
     
         14 . The porous structure of  claim 10 , wherein the second geometric structure includes a polyhedron with four or more faces. 
     
     
         15 . The porous structure of  claim 14 , wherein at least one of the four or more faces of the polyhedron comprises a portion of the first geometric structure. 
     
     
         16 . The porous structure of  claim 10 , wherein the first geometric structure includes a first polyhedron with a first number of faces and the second geometric structure includes a second polyhedron with a second number of faces. 
     
     
         17 . The porous structure of  claim 16 , wherein the first number of faces equals the second number of faces. 
     
     
         18 . The porous structure of  claim 10 , wherein the set of boundary struts and the set of internal struts are formed from a powdered metal that is melted or sintered in a plurality of layers. 
     
     
         19 . A method for producing a porous three-dimensional structure, the method comprising:
 depositing and scanning successive layers of metal powder with a beam to form a porous three-dimensional structure comprising a plurality of unit cells and having predetermined geometric properties, each unit cell comprising a set of boundary struts and a set of internal struts, each unit cell comprising:   a first geometric structure defined by the set of boundary struts, and   a second geometric structure defined by the set of internal struts and at least one boundary strut in the set of boundary struts.   
     
     
         20 . The method of  claim 19 , comprising depositing and scanning the successive layers of metal powder on a substrate, wherein the substrate and the porous three-dimensional structure form at least a portion of an implant.