Patent Publication Number: US-2022218487-A1

Title: Surgical implant devices incorporating porous surfaces and associated method of manufacture

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present patent application/patent is a continuation (CON) of co-pending U.S. patent application Ser. No. 16/788,353, filed on Feb. 12, 2020, which is a continuation-in-part (CIP) of co-pending U.S. patent application Ser. No. 14/339,508, filed on Jul. 24, 2014, the contents of both of which are incorporated in full by reference herein. U.S. patent application Ser. No. 14/339,508 claims the benefit of priority of: (1) U.S. Provisional Patent Application No. 61/857,824, filed on Jul. 24, 2013, (2) U.S. Provisional Patent Application No. 61,885,778, filed on Oct. 2, 2013, and (3) U.S. Provisional Patent Application No. 61/916,469, filed on Dec. 16, 2013, the contents of all of which are also incorporated in full by reference herein. U.S. patent application Ser. No. 14/339,508 is also a continuation-in-part (CIP) of U.S. patent application Ser. No. 13/530,048, filed on Jun. 21, 2012, which claims the benefit of priority of: (1) U.S. Provisional Patent Application No. 61/587,336, filed on Jan. 17, 2012, and (2) U.S. Provisional Patent Application No. 61/595,249, filed on Feb. 6, 2012, the contents of all of which are further incorporated in full by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to novel surgical implant devices incorporating porous surfaces. More specifically, the present disclosure relates to novel surgical implant devices incorporating porous surfaces for enhancing bony fixation and purchase when implanted. These porous surfaces are formed via novel additive manufacturing techniques and, optionally, novel post-processing manufacturing techniques. They include novel lattice structures and needle-like protrusions. 
     BACKGROUND 
     When various surgical implant devices, all well known to those of ordinary skill in the art, are placed adjacent to or between bony surfaces, it is desirable that adequate friction is present to hold them in place and that surfaces are available for bony fixation and purchase over time. Accordingly, these surgical implant devices often incorporate mechanically-manufactured friction surfaces or utilize friction coatings or bondings for such purposes. However, these mechanically-manufactured friction surfaces, typically consisting of teeth, grooves, striations, or the like that impart a degree of surface porosity, are often not adequate and do little to promote bony purchase. Similarly, these friction coatings or bondings may delaminate and fail. 
     Thus, what are still needed in the art are improved surgical implant devices that incorporate essentially-integral friction surfaces that are strong and durable, and that provide adequate surface area for bony fixation and purchase, while still being economical to manufacture. Improved additive and post-processing manufacturing techniques now make this possible. 
     SUMMARY 
     In one exemplary embodiment, the present disclosure provides a surgical implant device, including: a body portion; and one or more surfaces including a plurality of protruding structures; wherein the body portion and the one or more surfaces including the plurality of protruding structures are integrally formed. The one or more surfaces including the plurality of protruding structures are formed by an additive manufacturing process. The plurality of protruding structures include a plurality of needles. Optionally, the plurality of protruding structures include a plurality of needles that are disposed substantially perpendicular to the body portion. Alternatively, the plurality of protruding structures include a plurality of needles that are disposed at an angle to the body portion. Preferably, the plurality of protruding structures include a plurality of needles that include titanium. The body portion defines a hollow interior cavity. Optionally, the body portion defines one or more ports that are configured to receive a bone screw. The body portion defines one or more ports that are configured to allow bony ingrowth. The surgical implant device includes one of an anterior lumbar interbody fusion cage, a posterior lumbar interbody fusion cage, a transforaminal lumbar interbody fusion cage, an oblique lumbar interbody fusion cage, a cervical cage, and a bone screw. 
     In another exemplary embodiment, the present disclosure provides a method for manufacturing a surgical implant device, including: providing a body portion; and forming one or more surfaces including a plurality of protruding structures on an exterior portion of the body portion; wherein the body portion and the one or more surfaces including the plurality of protruding structures are integrally formed. The one or more surfaces including the plurality of protruding structures are formed by an additive manufacturing process. The plurality of protruding structures include a plurality of needles. Optionally, the plurality of protruding structures include a plurality of needles that are disposed substantially perpendicular to the body portion. Alternatively, the plurality of protruding structures include a plurality of needles that are disposed at an angle to the body portion. Preferably, the plurality of protruding structures include a plurality of needles that include titanium. The body portion defines a hollow interior cavity. Optionally, the body portion defines one or more ports that are configured to receive a bone screw. The body portion defines one or more ports that are configured to allow bony ingrowth. 
     In a further exemplary embodiment, the present disclosure provides a surgical implant device, including: an implant body; a porous layer disposed adjacent to the implant body, wherein the porous layer includes a lattice of intersecting struts; and a plurality of needle structures protruding from the porous layer opposite the implant body, wherein at least some of the plurality of needle structures traverse the porous layer and are anchored to the implant body. The plurality of needle structures that traverse the porous layer and are anchored to the implant body are coupled to one or more intersecting struts of the lattice. Optionally, some of the plurality of needle structures are spaced apart from the implant body and are anchored only to the porous layer. Preferably, one or more of the implant body, the porous layer, and the plurality of needle structures are formed by an additive manufacturing technique. Optionally, one or more of the implant body, the porous layer, and the plurality of needle structures include a titanium material. The intersecting struts of the lattice have a plurality of thicknesses, lengths, cross-sectional shapes, and intersection points. Optionally, the plurality of needle structures are disposed substantially normal to a surface of the implant body. Optionally, the plurality of needle structures are disposed randomly across a surface of the implant body. The plurality of needle structures are disposed across the surface of the implant body with a density of about 0.3 needles/mm 2 . Optionally, each of the plurality of needle structures has a substantially rectangular cross-sectional shape. 
     In a still further exemplary embodiment, the present disclosure provides a method for manufacturing a surgical implant device, including: providing an implant body; disposing a porous layer adjacent to the implant body, wherein the porous layer includes a lattice of intersecting struts; and providing a plurality of needle structures protruding from the porous layer opposite the implant body, wherein at least some of the plurality of needle structures traverse the porous layer and are anchored to the implant body. The plurality of needle structures that traverse the porous layer and are anchored to the implant body are coupled to one or more intersecting struts of the lattice. Optionally, some of the plurality of needle structures are spaced apart from the implant body and are anchored only to the porous layer. Preferably, the providing, disposing, and providing steps include, using a software application: defining a melt volume corresponding to a volume occupied by the implant body; defining a structure volume corresponding to a volume occupied by the porous layer; defining a needle volume corresponding to a volume occupied by the plurality of needle structures; formulating a lattice pattern within the structure volume; formulating a needle pattern within the needle volume; and additively manufacturing one or more of the implant body, the porous layer using the lattice pattern, and the plurality of needle structures using the needle pattern. The intersecting struts of the lattice have a plurality of thicknesses, lengths, cross-sectional shapes, and intersection points. Optionally, the plurality of needle structures are disposed substantially normal to a surface of the implant body. Optionally, the plurality of needle structures are disposed randomly across a surface of the implant body. The plurality of needle structures are disposed across the surface of the implant body with a density of about 0.3 needles/mm 2 . Optionally, each of the plurality of needle structures has a substantially rectangular cross-sectional shape. The method for manufacturing the surgical implant device further includes surface treating a bone opposition surface of one or more of the implant body, the porous layer, and the plurality of needle structures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is illustrated and described herein with reference to the various drawings, in which like reference numbers are used to denote like device components/method steps, as appropriate, and in which: 
         FIG. 1  depicts an exemplary method for producing surgical implant devices having osteo-derived and/or osteo-porous surface(s). 
         FIG. 1A  depicts an exemplary method for producing surgical implant devices having osteo-derived and/or osteo-porous surface(s) with additional outwardly-protruding “needles.” 
         FIG. 1B  depicts an exploded section of a computer-generated rendering of an exemplary osteo-derived and/or osteo-porous surface with outwardly-protruding needles. 
         FIG. 1C  conceptually depicts various exemplary shapes of outwardly-protruding needles (including, from left to right, tubular, rod-shaped, conical, square/rectangular, and barbed/irregular) useful with the present disclosure. 
         FIG. 1D  conceptually depicts an exemplary surgical implant device surface containing a uniform distribution of outwardly-protruding needles. 
         FIG. 1E  conceptually depicts an exemplary surgical implant device surface containing a non-uniform distribution of outwardly-protruding needles. 
         FIG. 1F  conceptually depicts an exemplary surgical implant device surface containing a gradient distribution of outwardly-protruding needles. 
         FIG. 1G  conceptually depicts an exemplary osteo-porous, osteo-derived, and/or trabecular surgical implant device surface containing a randomized distribution of outwardly-protruding needles. 
         FIG. 1H  conceptually depicts an exemplary cross-section of an implant surface containing a randomized distribution of needle heights. 
         FIG. 1I  conceptually depicts an exemplary cross-section of an implant surface containing an exemplary osteo-porous, osteo-derived, and/or trabecular coating with needles anchored to the underlying substrate. 
         FIG. 1J  conceptually depicts an exemplary cross-section of an implant surface containing an exemplary osteo-porous, osteo-derived, and/or trabecular coating with needles anchored to the osteo-porous, osteo-derived, and/or trabecular coating. 
         FIG. 1K  conceptually depicts an exemplary cross-section of an implant surface containing an exemplary osteo-porous, osteo-derived, and/or trabecular coating with uniformly tilted needles anchored to the underlying substrate. 
         FIG. 1L  conceptually depicts an exemplary cross-section of an implant surface containing an exemplary osteo-porous, osteo-derived, and/or trabecular coating with non-uniformly tilted needles anchored to the underlying substrate. 
         FIG. 2A  depicts preferred process flows for manufacturing abrasive-blasted implants in accordance with the disclosure. 
         FIG. 2B  depicts alternative process flows for manufacturing abrasive-blasted implants in accordance with the disclosure. 
         FIGS. 3A and 3B  depict exemplary SEM views of porous/trabecular metal sections fabricated by additive manufacturing in accordance with the disclosure, but not subjected to a post-fabrication abrasive blast step. 
         FIGS. 4A and 4B  depict exemplary SEM views of porous/trabecular metal sections fabricated by additive manufacturing in accordance with the disclosure, after being subjected to a post-fabrication abrasive blast step. 
         FIG. 5A  conceptually depicts a 2-D rendering of a cubic lattice structure, with no node perturbation and no strut size randomization. 
         FIG. 5B  conceptually depicts a 3-D rendering of the cubic lattice structure, with no node perturbation and no strut size randomization. 
         FIG. 5C  conceptually depicts a 2-D rendering of a cubic lattice structure, with 20% node perturbation and no strut size randomization. 
         FIG. 5D  conceptually depicts a 3-D rendering of the cubic lattice structure, with 20% node perturbation and no strut size randomization. 
         FIG. 5E  conceptually depicts a 2-D rendering of a cubic lattice structure, with 40% node perturbation and no strut size randomization. 
         FIG. 5F  conceptually depicts a 3-D rendering of the cubic lattice structure, with 40% node perturbation and no strut size randomization. 
         FIG. 5G  conceptually depicts a 2-D rendering of a cubic lattice structure, with 20% node perturbation and 100% strut size randomization. 
         FIG. 5H  conceptually depicts a 3-D rendering of the cubic lattice structure, with 20% node perturbation and 100% strut size randomization. 
         FIG. 5I  conceptually depicts a 2-D rendering of a dodecahedron lattice structure, with no node perturbation and no strut size randomization. 
         FIG. 5J  conceptually depicts a 3-D rendering of the dodecahedron lattice structure, with no node perturbation and no strut size randomization. 
         FIG. 5K  conceptually depicts a 2-D rendering of a dodecahedron lattice structure, with 20% node perturbation and no strut size randomization. 
         FIG. 5L  conceptually depicts a 3-D rendering of the dodecahedron lattice structure, with 20% node perturbation and no strut size randomization. 
         FIG. 6A  depicts an illustrative, irregular (e.g., trabecular, osteo-porous, and/or osteo-derived) unit cell appropriate for additive manufacture in accordance with the disclosure. 
         FIG. 6B  shows the unit cell of  FIG. 6A  repeated in a 3×3 array. 
         FIG. 6C  shows the unit cell of  FIG. 6A  repeated in a 6×6 array. 
         FIG. 6D  shows an isometric view of a 9×9 array of the unit cell of  FIG. 6A . 
         FIG. 6E  shows the unit cell of  FIG. 6A  patterned across the surface of an acetabular shell. 
         FIG. 6F  shows the unit cell of  FIG. 6A  patterned across the surface of an ALIF cage “blank.” 
         FIG. 7  illustrates one exemplary embodiment of the additive manufacturing modeling and file-generation methodology of the present disclosure, by which the associated structure(s) are formed. 
     
    
    
     DETAILED DESCRIPTION 
     Generally speaking, and without intending to be limiting, one aspect of the disclosure relates to improved medical implants that include, for example, at least the following: a primary structure formed from metal; and at least one needle-populated, metallic surface portion formed on at least one exterior portion of the primary structure, the at least one surface portion located such that it engages with a patient&#39;s bone when the implant is implanted in the patient. Such needle-populated, metallic surface portions may contain, for example, a collection of at least fifty, a hundred, two hundred, five-hundred or more needles, and may be further characterized by at least one, two, three, four, five or more of the following characteristics: (a) the needles in the collection are all oriented substantially normal to the surface portion; (b) the needles in the collection are all oriented in substantially the same direction, with the direction being other than normal to the surface portion; (c) the needles in the collection are all oriented in substantially the same direction, with the direction being other than normal to the surface portion, but within 15 degrees from the normal direction; (d) the needles in the collection are all oriented in substantially the same direction, with the direction being other than normal to the surface portion, and more than 15 degrees from the normal direction; (e) the collection includes needles oriented in at least three different directions relative to the surface portion; (f) the collection includes needles oriented in at least five different directions relative to the surface portion, with all of the needles oriented within 20 degrees from the surface portion normal direction; (g) all of the needles in the collection have substantially the same height; (h) the collection includes needles of at least three different heights; (i) all of the needles in the collection have substantially the same shape; (j) the collection includes needles of at least two different shapes; (k) the needles are distributed substantially uniformly over the surface portion; (l) the needles are distributed non-uniformly over the surface portion; (m) all of the needles in the collection are anchored to the primary structure; (n) most of the needles in the collection are anchored to the primary structure; (o) most of the needles in the collection are anchored to structural elements contained within an osteo-porous, osteo-derived or trabecular coating on the at least one exterior portion of the primary structure; and/or (p) all of the needles in the collection are anchored to structural elements contained within an osteo-porous, osteo-derived or trabecular coating on the at least one exterior portion of the primary structure. The at least one exterior portion preferably includes at least one osteo-porous surface, which may comprise at least one osteo-derived surface. The at least one osteo-porous surface and the needles may be simultaneously formed by an additive manufacturing process, such as, but not limited to, EBM or DMSLS. The primary structure may comprise, for example, a dental implant, a foot-and-ankle or long-bone osteotomy wedge, an intervertebral fusion device, a tibial/femoral augment or spacer, a tibial tray portion of a knee implant, a femoral component portion of a knee implant, a primary hip implant, a revision hip implant, a hip trauma component, an acetabular cup, a hip acetabular augment, or other appropriate structure. 
     Again, generally speaking, and without intending to be limiting, another aspect of the disclosure relates to method(s) for making a medical implants with at least one osteo-porous surface by, for example: forming at least a portion of a primary structure of the implant; and forming at least one needle-populated, metallic surface portion on at least one exterior portion of the primary structure using an additive manufacturing technique, the at least one needle-populated surface portion located such that it engages with a patient&#39;s bone when the implant is implanted in the patient. 
     Other aspects of the disclosure relate to additional features, structures, processes and materials depicted in the figures and/or described herein. 
     Referring to  FIG. 1 , the exemplary flow starts with a spongy bone sample  10 , which is micro CT scanned to obtain 3D scan data  12 , which is then processed into solid model data representing an osteo-porous or osteo-derived texture  14 , 16 . This texture data is then combined with data representing the overall implant geometry to create a fabrication file  18  for use by either of the manufacturing steps  20 , 22  that follow. 
     The fabrication file may utilize any recognizable solid model specification, such as “.amf” format or “.stl” format, and may be embodied on any sort of permanent storage medium (e.g., CD, CD-ROM, flash), semi-permanent (e.g., SRAM) or transitory (e.g., DRAM) storage medium, or embodied in a coded data signal. 
     Referring to  FIG. 1A , an additional step can be inserted that adds outwardly-protruding “needles” on the outer surface(s) of the osteo-porous and/or osteo-derived coating(s)  24 . Referring to  FIGS. 1B and 1C , such needles  30  substantially increase the coefficient of friction of the implant surface  32 . Having a high coefficient of friction is clinically advantageous because it provides stronger initial fixation, which is important before bone is able to grow onto/into the porous structure. Such needles  30  can be uniformly or non-uniformly distributed along the porous surface. Likewise, various shapes for the needles  30  are possible, including rectangular, pyramidal, conical, tube-shaped, barbed, etc. Also, the needles  30  need not be oriented exactly normal to the exterior surface, but are preferably oriented in a substantially normal (e.g., within +/−15 degrees from normal) orientation. Furthermore, the orientation and/or shape of all needles  30  need not be the same, and the needles  30  may be rendered on selected portions, or the entirety, of the exterior coated surface(s). 
       FIG. 1D  conceptually depicts an exemplary surgical implant device surface, specifically an acetabular cup  34 , containing a uniform distribution of outwardly-protruding needles  30  disposed on a surface  32  thereof.  FIG. 1E  conceptually depicts an exemplary surgical implant device surface, specifically an acetabular cup  34 , containing a non-uniform distribution of outwardly-protruding needles  30  disposed on a surface  32  thereof.  FIG. 1F  conceptually depicts an exemplary surgical implant device surface, specifically an acetabular cup  34 , containing a gradient distribution of outwardly-protruding needles  30  disposed on a surface  32  thereof.  FIG. 1G  conceptually depicts an exemplary surgical implant device surface, specifically an acetabular cup  34 , containing a randomized distribution of outwardly-protruding needles  30  disposed on a surface  32  thereof. 
       FIGS. 1H and 1I  conceptually depict an exemplary cross-section of a generic implant surface  32  containing a randomized distribution of needles  30 .  FIG. 1H  illustrates that this collection of needles  30  can be randomized in terms of distribution and/or needle length/height with respect to the implant surface  32 . 
     Referring specifically to  FIG. 1I , the methodology and implant of the present disclosure generate and provide a surface  32  that includes the implant body  40  and a porous layer  50  that is disposed directly adjacent to the implant body  40 . The porous layer  50  can be additively manufactured on top of the implant body  40 , or can be additively manufactured with the implant body  40 . The porous layer  50  consists of a bone-interfacing lattice of macroscopic, randomly distributed stochastic struts  52  of various thicknesses, shapes, and intersection points. This lattice is comparable to cancellous bone in terms of pore size and overall porosity, thus it elicits a favorable bone response when applied to the bone-opposition surfaces of the associated implant to which it is applied. The needles  30  are additively manufactured with the porous layer  50  and/or the implant body  50  and some or all of the needles  30   a  protrude from and are anchored directly to the implant body  40 , through the porous layer  50 , and from the bone-opposition surface of the porous layer  50 , forming regularly or randomly-arranged friction structures protruding from the bone-opposition surface of the porous layer  50 . This provides advantageous needle strength and stability. Within the porous layer  50 , these penetrating needles  30   a  are integrally formed with or otherwise anchored to adjacent of the struts of the lattice, again providing advantageous needle strength and stability. In one preferred embodiment, all needles  30  are planted 0.004-0.006 in. into the solid substrate, either physically or for behavioral modeling purposes (having a corresponding support stiffness), and extend about 0.008 in. above the bone-opposition surface of the porous layer  50 , with a plurality of intervening lattice strut connections along the length of each needle  30 . Here, the needles are 0.2 mm×0.2 mm rectangular prisms with constant cross-sections. The preferred needle density is 0.3 needles/mm 2  or 1 needle every 3.33 mm 2  for optimal bone friction engagement. The needles  30  are largely disposed normal to the bone-opposition surface of the porous layer  50  and the implant body  40 , but may be angled with respect to one another due to curvature of the bone-opposition surface of the porous layer  50  and the implant body  40 . The finished porous layer-needle construct is blasted with calcium phosphate or otherwise surface treated to promote roughness of the resulting bone-engagement structure. 
       FIG. 1J  conceptually depicts an exemplary cross-section of an implant surface containing an exemplary osteo-porous, osteo-derived, and/or trabecular coating  50  with needles  30   b  anchored only to the bone-opposition surface of the osteo-porous, osteo-derived, and/or trabecular coating  50  and not the underlying implant body  40 .  FIG. 1K  conceptually depicts an exemplary cross-section of an implant surface containing an exemplary osteo-porous, osteo-derived, and/or trabecular coating  50  with uniformly tilted needles  30   a , 30   b  variously anchored to both the bone-opposition surface of the osteo-porous, osteo-derived, and/or trabecular coating  50  and the underlying implant body  40 .  FIG. 1L  conceptually depicts an exemplary cross-section of an implant surface containing an exemplary osteo-porous, osteo-derived, and/or trabecular coating  50  with non-uniformly tilted needles  30   a , 30   b  variously anchored to both the bone-opposition surface of the osteo-porous, osteo-derived, and/or trabecular coating  50  and the underlying implant body  40 . Utilizing these or similar techniques, one can efficiently and advantageously form (and/or finish) implants of the sort depicted herein. 
     Referring to  FIGS. 2A and 2B , two preferred process flows for fabricating and finishing implants using an abrasive blast are shown. In the first  60 , the base metal portion of the implant is formed by machining or additive manufacturing  62 , 64 , prior to the porous layer and needles being additively disposed on the bone-opposition surface of the implant  66 . The resulting structure is then finished with an abrasive blast  68 . In the second  70 , the base metal portion of the implant is again formed by machining or additive manufacturing  72 , 74 , prior to the porous layer and needles being additively disposed on the bone-opposition surface of the implant  76 . The resulting structure is then machined into the final implant form  78  and finished with an abrasive blast  80 . Alternatively, the resulting structure is then abrasively blasted  82  and finished into the final implant form by machining  84 . 
       FIGS. 3A and 3B and 4A and 4B  contrastingly depict SEM images of porous implant sections that have and have not undergone an abrasive blasting step. As can be seen from the images, the non-blasted samples are mostly smooth if viewed on the  20  or  100 -μm scale, whereas the blasted samples are almost entirely rough, when viewed at similar magnification. This blast process creates a texture approximately 1-20 μm in scale. This is an ideal scale for microtexture because it helps osteoblasts adhere to the titanium struts and needles. The blast material is not deposited on the struts and needles (as an HA coating would be). It simply textures the titanium surface by erosion. 
     In accordance with the disclosure, the preferred abrasive blast process utilizes an MCD apatitic abrasive (multi-phased calcium phosphate containing HA, TCP and other CaP phases. The blast media has a 125-180-μm size range, for example. The process utilizes a Comco AccuFlo® standard tank micro-abrasive blaster, equipped with Simoom® Technology and a PowderGate® valve. The tank orifice is 0.40 in.; the nozzle is 0.060 in.; the pressure is 90+/−5 psi. A satisfactory roughness has been achieved when the blast does not further affect the visual appearance, specifically the color and reflectivity of the device. Machined devices may require a blast touch up subsequent to machining. 
       FIGS. 5A-5L  illustratively depict the concept of slightly-irregular lattices that are ideally adapted for additive manufacturing in accordance with the present disclosure. As shown in these figures, node perturbation refers to the location of intersecting struts. In accordance with this aspect of the disclosure, such intersection locations can be randomized such that the node deviates from a uniform lattice by a randomized distance or degree. Strut size randomization refers to a deviation in cross-sectional dimension (e.g., strut diameter), as well as shape and length. Discrete struts in a lattice could have different cross-sectional sizes, or the struts could have a diameter gradient from one end to the other. These parameters can be randomized for greater diversity in the lattice&#39;s geometry. Such slightly-irregular lattices can be used to fabricate any sort of medical implant for which regular lattices might otherwise be used. 
     Exemplary fusion/fixation devices fabricated by the additive techniques of the present disclosure may utilize multi-circular cross-sectional profiles (either uniform or tapered), and preferably include exterior needles, preferably oriented in a direction that would resist removal of the implant. Multi-circular cross-sectional profiles, by way of example, have the distinct advantage of not requiring one or more bore broaching steps, thus making insertion quicker and reducing patient infection risk. 
     It should be understood that the novel structures disclosed and enabled by the present disclosure are not limited exclusively to those manufactured using additive manufacturing. Indeed, as persons skilled in the art will appreciate, other known surface modification techniques may be used to produce the osteoporous, osteo-derived, and/or needle-containing textures of the inventive implants. 
     Again, generally speaking, and without intending to be limiting, one aspect of the present disclosure relates to improved medical implants that include, for example, at least the following: a primary structure formed from metal; and at least one needle-populated, metallic surface portion formed on at least one exterior portion of the primary structure, the at least one surface portion located such that it engages with a patient&#39;s bone when the implant is implanted in the patient. Such needle-populated, metallic surface portions may contain, for example, a collection of at least fifty, a hundred, two hundred, five-hundred or more needles, and may be further characterized by at least one, two, three, four, five or more of the following characteristics: (a) the needles in the collection are all oriented substantially normal to the surface portion; (b) the needles in the collection are all oriented in substantially the same direction, with the direction being other than normal to the surface portion; (c) the needles in the collection are all oriented in substantially the same direction, with the direction being other than normal to the surface portion, but within 15 degrees from the normal direction; (d) the needles in the collection are all oriented in substantially the same direction, with the direction being other than normal to the surface portion, and more than 15 degrees from the normal direction; (e) the collection includes needles oriented in at least three different directions relative to the surface portion; (f) the collection includes needles oriented in at least five different directions relative to the surface portion, with all of the needles oriented within 20 degrees from the surface portion normal direction; (g) all of the needles in the collection have substantially the same height; (h) the collection includes needles of at least three different heights; (i) all of the needles in the collection have substantially the same shape; (j) the collection includes needles of at least two different shapes; (k) the needles are distributed substantially uniformly over the surface portion; (l) the needles are distributed non-uniformly over the surface portion; (m) all of the needles in the collection are anchored to the primary structure; (n) most of the needles in the collection are anchored to the primary structure; (o) most of the needles in the collection are anchored to structural elements contained within an osteo-porous, osteo-derived or trabecular coating on the at least one exterior portion of the primary structure; and/or (p) all of the needles in the collection are anchored to structural elements contained within an osteo-porous, osteo-derived or trabecular coating on the at least one exterior portion of the primary structure. The at least one exterior portion preferably includes at least one osteo-porous surface, which may comprise at least one osteo-derived surface. The at least one osteo-porous surface and the needles may be simultaneously formed by an additive manufacturing process, such as, but not limited to, EBM or DMSLS. The primary structure may comprise, for example, an ALIF cage, portions of a bone screw, a dental implant, a foot-and-ankle or long-bone osteotomy wedge, an intervertebral fusion device, a tibial/femoral augment or spacer, a tibial tray portion of a knee implant, a femoral component portion of a knee implant, a primary hip implant, a revision hip implant, a hip trauma component, an acetabular cup, a hip acetabular augment, or other appropriate structure. 
     Again, generally speaking, and without intending to be limiting, another aspect of the present disclosure relates to method(s) for making a medical implants with at least one osteo-porous surface by, for example: forming at least a portion of a primary structure of the implant; and forming at least one needle-populated, metallic surface portion on at least one exterior portion of the primary structure using an additive manufacturing technique, the at least one needle-populated surface portion located such that it engages with a patient&#39;s bone when the implant is implanted in the patient. 
     The exemplary flow starts with a spongy bone sample, which is micro CT scanned to obtain 3D scan data, which is then processed into solid model data representing an osteo-porous or osteo-derived texture. This texture data is then combined with data representing the overall implant geometry to create a fabrication file for use by either of the manufacturing steps that follow. The fabrication file may utilize any recognizable solid model specification, such as “.amf” format or “.stl” format, and may be embodied on any sort of permanent storage medium (e.g., CD, CD-ROM, flash), semi-permanent (e.g., SRAM) or transitory (e.g., DRAM) storage medium, or embodied in a coded data signal. 
     An additional step can be inserted that adds outwardly-protruding “needles” on the outer surface(s) of the osteo-porous and/or osteo-derived coating(s). Such needles substantially increase the coefficient of friction of the coating. Having a high coefficient of friction is clinically advantageous because it provides stronger initial fixation, which is important before bone is able to grow onto/into the porous structure. Such needles can be uniformly or non-uniformly distributed along the porous surface. Likewise, various shapes for the needles are possible, including rectangular, pyramidal, conical, tube-shaped, etc. Also, the needles need not be oriented exactly normal to the exterior surface, but are preferably oriented in a substantially normal (e.g., within +/−15 degrees from normal) orientation. Furthermore, the orientation and/or shape of all needles need not be the same, and the needles may be rendered on selected portions, or the entirety, of the exterior coated surface(s). 
     Utilizing these or similar techniques, one can efficiently and advantageously form (and/or finish) implants. Finally, it should be understood that the novel structures disclosed and enabled by the present disclosure are not limited exclusively to those manufactured using additive manufacturing. Indeed, as persons skilled in the art will appreciate, other known surface modification techniques may be used to produce the osteoporous, osteo-derived, and/or needle-containing textures of the inventive implants. 
       FIG. 6A  depicts an illustrative, irregular (e.g., trabecular, osteo-porous, and/or osteo-derived) unit cell appropriate for additive manufacture in accordance with the disclosure.  FIG. 6B  shows the unit cell of  FIG. 6A  repeated in a 3×3 array.  FIG. 6C  shows the unit cell of  FIG. 6A  repeated in a 6×6 array.  FIG. 6D  shows an isometric view of a 9×9 array of the unit cell of  FIG. 6A .  FIG. 6E  shows the unit cell of  FIG. 6A  patterned across the surface of an acetabular shell.  FIG. 6F  shows the unit cell of  FIG. 6A  patterned across the surface of an ALIF cage “blank.” 
     Referring to  FIG. 7 , the methodology  100  and implant of the present disclosure generate and provide a surface that includes the implant body  40  (or “melt”) and a porous layer  50  (or “structure”) that is disposed directly adjacent to the implant body  40 . The porous layer  50  can be additively manufactured on top of the implant body  40 , or can be additively manufactured with the implant body  40 . The porous layer  50  consists of a bone-interfacing lattice of macroscopic, randomly distributed stochastic struts  52  of various thicknesses, shapes, and intersection points. This lattice is comparable to cancellous bone in terms of pore size and overall porosity, thus it elicits a favorable bone response when applied to the bone-opposition surfaces of the associated implant to which it is applied. The generation of the overall structure is accomplished through several CAD modeling programs in the following data preparation process flow. CAD modeling software is used to generate the design envelope (i.e. the volumes) and spatial relationship (i.e. the overlap) of the various structural elements  102 , 104 . The overall structure is comprised of three specific volume elements: the melt volume, structure volume, and the needle volume. The melt volume is the CAD volume that defines the solid substrate that the structure and needles interface and overlap to ensure a mechanical interface during the additive manufacturing process. For most scenarios, the melt volume is the bulk of the device. The structure volume is the CAD volume that defines the virtual boundary conditions for which the random, stochastic structure will be generated. The structure volume is purely solid and without any lattice. The needle volume is the CAD volume that defines the virtual boundary conditions for which the random, protrusions will extend beyond the regions of the structure volume. The needle volume is purely solid and without any needles (i.e. protrusions). A CAD assembly combines the melt volume, structure volume, and needle volume part models. The structure volume and needle volume elements overlap with the melt volume within the defined coordinate system through the mate interface GUI. This overlap is based on the resolution and accuracy of the intended additive manufacturing technology for which the device will be manufactured. After the CAD assembly has been defined, the models are exported as .STL file format. The .STL files are imported into additional CAD software and used to generate the structure and needles from the structure volume and needle volume elements that were previously defined  106 . Using the structure volume, the user executes the GUI algorithm. This algorithm applies a unit cell within a defined volume relative to the CAD environment&#39;s coordinate system. The algorithm executes a Boolean operation between the array of unit cells and the structure-volume to yield only the portions of the unit cell within the volume. The overall structure utilizes a porous structure unit cell of defined dimensions, shape, and volume. The algorithm is used to duplicate the porous structure unit cell as an array across the structure volume element and then trim the unit cells within the boundaries of the structure volume. The result is the structure; a random, stochastic lattice that fills the volume of the original structure volume envelope. Similar to structure generation, needles are generated via an intersection Boolean operation between the needle volume element and a pre-programmed. STL file that was generated by an equation-driven algorithm. The pre-programmed needle-element is imported into the CAD software and spatially-aligned with the needle volume. The Boolean is executed and the resulting geometry is an array of randomly located needles (i.e. protrusions) within the boundaries previously defined by the needle volume. After successfully generating the structure and needles, the components are exported as .STL files. The .STL files are then imported into additive manufacturing technology-specific software programs in preparation for the additive manufacturing process. The technology-specific software programs slice the CAD models at a defined thickness acceptable for the additive manufacturing equipment, define the sequence of part build order, and apply exposure strategies. The result of these programs is a build file that is imported and executed on the additive manufacturing machine to yield a physical part. 
     It is to be recognized that, depending on the example, certain acts or events of any of the techniques described herein can be performed in a different sequence, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the techniques). Moreover, in certain examples, acts or events may be performed concurrently, e.g., through multi-threaded processing, interrupt processing, or multiple processors, rather than sequentially. 
     In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. 
     Computer-readable media may include computer-readable storage media, which corresponds to tangible media, such as data storage media, or communication media, including any medium that facilitates transfer of a computer program from one place to another, e.g., according to a communication protocol. In this manner, computer-readable media generally may correspond to (1) a tangible computer-readable storage medium that is non-transitory or (2) a communication medium, such as a signal or carrier wave. Data storage media may be any available media that can be accessed by one or more computers or one or more processors to retrieve instructions, code, and/or data structures for implementation of the techniques described in this disclosure. A computer program product may include a computer-readable medium. 
     By way of example, and not limitation, such computer-readable storage media can include random-access memory (RAM), read-only memory (ROM), electrically erasable-programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, magnetic disk storage, or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR), radio frequency (RF), and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies, such as IR, RF, and microwave are included in the definition of medium. It should be understood, however, that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but are instead directed to non-transitory, tangible storage media. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), and Blu-ray disc, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. 
     Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), complex programmable logic devices (CPLDs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor,” as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and/or software modules. Also, the techniques could be fully implemented in one or more circuits or logic elements. 
     The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses, including an integrated circuit (IC) or a set of ICs (e.g., a chip set). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but do not necessarily require realization by different hardware units. Rather, as described above, various units may be combined in a hardware unit or provided by a collection of interoperative hardware units, including one or more processors as described above, in conjunction with suitable software and/or firmware. 
     Although the present disclosure is illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present disclosure, are contemplated thereby, and are intended to be covered by the following non-limiting claims for all purposes.