Method for forming an implant with a porous surface using thermal bonding

Abstract

To provide methods of forming an implant including heat-bonding a porous material to an insert and heat-bonding the insert to an implant body.SOLUTION: A method of forming an orthopaedic implant includes: heat-bonding a porous material to a surface of an insert to form a bonded insert; placing a bare portion of the bonded insert in an opening formed in a material of an implant body; and-heat bonding the bare portion to the material to bond the bonded insert to the implant body.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This is a non-provisional application based on U.S. Provisional Patent Application No. 62 / 835,600, filed April 18, 2019, entitled "Method of Forming an Implant with a Porous Surface Using Thermal Bonding," which is incorporated herein by reference.

[0002] Background of the Invention 1. Field of the Invention The present invention relates to a method for forming an implant with a porous surface, and in particular to a method for forming an implant using thermal bonding. 2. Description of Related Technology Orthopedic implants often incorporate one or more porous materials that allow for cell infiltration and proliferation. Such porous materials may be combined with non-porous materials of the implant. Porous materials generally have lower strength and can be more difficult to shape than their non-porous counterparts, which increases manufacturing costs.

[0003] What is needed in the art is a method for forming orthopedic implants that is less expensive than known methods.

[0004] Summary of the Invention Exemplary embodiments disclosed herein provide a method of forming an implant that includes heat bonding a porous material to an insert and heat bonding the insert to an implant body.

[0005] In some embodiments provided by the present invention, a method of forming an orthopedic implant includes heat-bonding a porous material to a surface of an insert to form a bonded insert; placing a bare portion of the bonded insert in an opening formed in the material of an implant body; and heat-bonding the bare portion to the material to bond the bonded insert to the implant body.

[0006] In some exemplary embodiments provided by the present invention, an orthopedic implant includes an implant body having a surface with an opening formed therein; a bonded insert disposed within the opening and having a bare portion heat-bonded to the implant body and an adhesive portion bonded to the bare portion; and a porous ingrowth material bonded to the adhesive portion.

[0007] In some embodiments provided by the present invention, a method of forming an orthopedic implant includes placing a porous ingrowth material having a shape including at least one complex outer surface in contact with at least one bonding surface of an implant body; and thermally bonding the porous ingrowth material to the at least one bonding surface to form the orthopedic implant.

[0008] One potential advantage that may be realized by the exemplary embodiments disclosed herein is that the formation of the bonded insert and heat bonding of the bonded insert to the implant body may be quick and easy, thereby reducing the manufacturing costs of the orthopedic implant.

[0009] Another possible advantage that may be realized by the exemplary embodiments disclosed herein is that multiple orthopedic implants may be formed simultaneously in a heated vessel, such as a furnace, thereby further reducing manufacturing costs.

[0010] Yet another possible advantage that may be realized by the exemplary embodiments disclosed herein is that the difficulty and expense of fabricating orthopedic implants with porous ingrowth material having complex geometries may be reduced by using pre-bonded inserts or other methods to heat bond the porous ingrowth material to the implant body. [Brief explanation of the drawings]

[0011] The above and other features and advantages of the present invention, and the manner in which they are achieved, will become more apparent and the invention will be better understood by referring to the following description of the embodiments of the invention taken in conjunction with the accompanying drawings. [Figure 1] 1 is a top view of one exemplary embodiment of an orthopedic implant provided by the present invention, the orthopedic implant including a bonded insert heat-bonded to the implant body. [Figure 2] 2 is a cross-sectional view of the orthopedic implant shown in FIG. 1 taken along line 2-2. [Figure 3] 1 is a cross-sectional view of another exemplary embodiment of an orthopedic implant provided by the present invention, the implant including a bonded insert heat-bonded to an implant body having a relatively large opening. [Figure 4] 1 is a flow chart illustrating one exemplary embodiment of a method for forming an orthopedic implant provided by the present invention. [Figure 5] 1 is a cross-sectional view of one exemplary embodiment of a bonded insert assembly provided by the present invention for producing a pair of bonded inserts. [Figure 6] 1 is a cross-sectional view of one exemplary embodiment of a bonded insert including a tapered surface provided by the present invention. [Figure 7] 1 is a partially exploded cross-sectional view of one exemplary embodiment of an orthopedic implant including a cemented insert having a shoulder provided by the present invention; [Figure 8] 1 is a cross-sectional view of one exemplary embodiment of an orthopedic implant including a bonded insert with a porous ingrowth material having a complex outer surface. [Figure 9] 10 is a cross-sectional view of another exemplary embodiment of an orthopedic implant including a bonded insert with a porous ingrowth material having a complex outer surface. [Figure 10] 10 is a cross-sectional view of yet another exemplary embodiment of an orthopedic implant including a bonded insert with a porous ingrowth material having a complex outer surface. [Figure 11] 1 is a flow chart illustrating another exemplary embodiment of a method for forming an orthopedic implant with a porous ingrowth material having a complex surface provided by the present invention. [Figure 12] 1 is an exploded view illustrating one exemplary embodiment of an orthopedic implant provided by the present invention, the implant comprising an implant body and a mating part bonded to the implant body. [Figure 13] 13 is a perspective view of the implant body shown in FIG. 12 with multiple walls defining an opening. [Figure 14] FIG. 14 is an enlarged perspective view of the implant body shown in FIGS. 12 and 13. [Figure 15] 1 is a perspective view illustrating another exemplary embodiment of an orthopedic implant provided by the present invention, including an implant body and a mating part, prior to bonding of the mating part to the implant body. FIG. [Figure 16A] FIG. 16 is a perspective view of the implant body shown in FIG. 15. [Figure 16B] FIG. 16B is another perspective view of the implant body shown in FIGS. 15 and 16A. [Figure 17] 1 is a cross-sectional view illustrating another exemplary embodiment of an orthopedic implant provided by the present invention, including an implant body and a mating part, prior to bonding of the mating part to the implant body. [Figure 18] 18 is another cross-sectional view of the orthopedic implant shown in FIG. 17. [Figure 19] 19 is a cross-sectional view of the orthopedic implant shown in FIGS. 17 and 18 after the mating parts have been bonded to the implant body. FIG. [Figure 20] 1 is a flowchart illustrating one exemplary embodiment of a method for forming an orthopedic implant including an implant body and a mating part bonded to the implant body provided by the present invention.

[0012] Corresponding reference characters represent corresponding parts throughout the several views. The examples set forth herein illustrate embodiments of the present invention, and such examples are not to be construed as limiting the scope of the invention in any way.

[0013] Detailed Description of the Invention Referring to the figures, and particularly to FIG. 1 , one exemplary embodiment of an orthopedic implant 100 formed in accordance with the present disclosure is shown. The implant 100 may take the form of a tibial implant, a femoral implant, an acetabular implant, a glenoid implant, a dental implant, or any other type of medical or veterinary implant. The orthopedic implant 100 includes a substrate 101, sometimes referred to as an “implant body,” having a plurality of inserts 110 adhered to the substrate 101. Each insert 110 may be, for example, a peg at least partially coated with a porous ingrowth material 112 and having an exposed surface 111 sized and shaped for insertion into an opening formed in bone or other tissue. In some embodiments, the insert 110 is comprised of one or more porous ingrowth materials without an underlying substrate. The insert 110 may comprise, for example, a metal such as titanium, stainless steel, or cobalt chromium, or a polymer such as polyetheretherketone. The porous ingrowth material 112 may be, for example, a porous metallic or polymeric material having a pore geometry selected to promote tissue ingrowth into the ingrowth material. Exemplary porous ingrowth materials that may be utilized include materials sold under the trade name OSTEOSYNC® by SITES MEDICAL®, Inc. of Columbia City, Indiana. The inserts 110 may each be adhered to the bottom surface of the substrate 101, which may also be at least partially coated with the porous ingrowth material to promote fixation of the implant.

[0014] 2, a cross-section of the implant 100 and several bonded inserts 110 is shown. Each insert 110 may have a bare portion 113 disposed within each opening 102 formed in the substrate 101 material and a bonded portion 114 bonded to the porous ingrowth material 112. As used herein, portion 113 is "bare" in the sense that it does not include the porous ingrowth material 112, but may still have a surface coating to inhibit corrosion of the material, for example. The bare portion 113 of the insert 110 may have a flange 115 extending perpendicularly away from the longitudinal axis LA of the insert 110 and defining the widest portion of the insert 110. The longitudinal axis LA extends through the bonded portion 114 of the insert 110, with the bonded portion 114 having a surface 111 bonded to the porous ingrowth material 112. In some embodiments, the flange 115 is also at least partially coated with a porous ingrowth material and / or has threads 116 that threadably engage with corresponding threads in the opening 102 to form a mechanical fastener prior to thermal bonding.

[0015] As can be seen in FIG. 2 , the opening 102 formed in the material can define an opening width OW that is smaller than the width FW of the flange 115 to prevent the flange 115 from easily removing from the opening 102 once it is positioned therein. The opening 102 can be defined by a plurality of walls 104 extending perpendicularly from a bottom surface 105 that defines a closed bottom of the opening 102; i.e., in some embodiments, the opening 102 is not formed entirely by the base / implant body 101. As can be seen in the exemplary embodiment of the orthopedic implant 300 shown in FIG. 3 , the implant body 301 can also include an opening 302 that defines an opening width OW2 that is the same as or slightly larger than the width FW of the flange 115. When the flange 115 is placed within the opening 102, 302, the porous ingrowth material may contact the walls 103, 303 of the opening 102, 302 and / or the surface of the material within which the opening 102, 302 is formed, thereby causing the porous ingrowth material 112 to substantially cover the opening 102.

[0016] To form the implants 100, 300 shown in Figures 1-3, one exemplary embodiment of an implant forming method 400 is provided and is illustrated in Figure 4. The method 400 includes thermally bonding 401 a porous material, such as the porous ingrowth material 112 described above, to the surface 111 of the insert to form the bonded insert 110. As used herein, "thermal bonding" refers to a bonding process that utilizes temperatures above room temperature to bond two components together without significant liquefaction of the material of either component. Typical thermal bonding techniques include, but are not limited to, diffusion bonding, which utilizes relatively low temperatures and high pressures, and sintering, which utilizes relatively high temperatures and low pressures. Another thermal bonding technique that may be utilized includes coating one or both of the components to be joined with a third material, such as polyetheretherketone, which is melted to bond the components together. Many different types of alternative thermal bonding techniques are known, depending on the materials of the components to be bonded together, and will not be further described for the sake of brevity.

[0017] The bonded insert 110 may have a bare portion 113, such as a flange 115, that is disposed 402 within an opening 102, 302 formed in a material, such as the material of the substrate / implant body 101, 301 of the implant 100. As discussed above, the bare portion 113 is not bonded to the porous material 112. To bond the bonded insert 110 to the material, the bare portion 113 may be heat bonded 403 to the material, resulting in an implant 100, 300 formed with the bonded insert 110. Alternatively, the bare portion 113 of the bonded insert 110 may be covered by a porous material and heat bonded to the material to bond the bonded insert 110 to the material.

[0018] Forming the implants 100, 300 by the above-described method 400 can result in several advantages. In known techniques, inserts such as posts are typically formed into the implant during casting, or alternatively, directly into machined, forged, or cast implants by machining the post. Once the post is formed, a porous ingrowth material is bonded to the post, which requires compacting the material against the post and implant during bonding. This process is difficult and time-consuming due to the relatively small size of the post and the difficulty of adequately compacting and holding the porous material against the post without damaging or rejecting the part.

[0019] In contrast, the method 400 described herein produces bonded inserts 110 that are thermally bonded to the material of the implant 100, 300. The bonded inserts 110 can be formed in relatively large batches by placing several unbonded inserts, with the porous ingrowth material pressed into them, in a diffusion bonding oven. After "cooking" the unbonded inserts and the porous ingrowth material 112 for a sufficient time and temperature to achieve a thermal bond, the formed bonded inserts 110 can be removed from the oven. The bonded inserts 110 are then ready to be thermally bonded to the substrate / implant body 101, 301. Thus, a large number of pre-fabricated bonded inserts 110 can be stored on-site to form implants 100, 300, for example, with multiple pegs, as needed. It has been found that the thermal bond between the bonded inserts 110 and the material of the implant 100, 300 is at least strong enough to exceed the functional strength requirements of many medical implants. Additionally, in some embodiments, the bare post can be bonded to the substrate / implant body 101, 301 and then the porous material can be applied to the bare post, for example, by plasma spraying or other methods, to provide the porous material to the post on implant components that are not easily fabricated with porous components. Thus, implants formed in accordance with the present disclosure can be manufactured significantly faster than using known techniques without compromising the strength or durability requirements of a wide variety of medical implants.

[0020] The method 400 also allows for the rapid creation of multiple different implant designs. It is well known that many implants have different numbers of pegs and peg locations. Using the disclosed method 400, multiple different implant styles with different numbers of pegs and peg locations can be created using pre-fabricated bonded inserts 110 by forming 404 the desired aperture pattern in the material of the substrate / implant body 101, 301 to form at least the apertures 102, 302, placing 402 the bare portions 113 of the bonded inserts 110 within the formed apertures 102, 302, and heat-bonding 403 the bare portions 113 to the material to bond the bonded inserts 110 to the material and form the implant. Implant blanks, generally having the shape of the finished implant but without the apertures, can be stored on-site. In this case, the implant can be created by forming 404 one or more apertures in the implant blank at desired locations, and then placing 403 the bare portions 113 of the bonded inserts 110 within the apertures 102, 302 and heat-bonding. It should thus be appreciated that the method 400 provided in accordance with the present disclosure is readily adaptable to the formation of many different types of implants using pre-fabricated, bonded inserts and implant blanks.

[0021] 5, in some embodiments, the bonded insert 110 is formed from a bonded insert assembly 500. The bonded insert assembly 500 may have a pair of flange ends 501A, 501B representing bare portions, and a porous ingrowth material 502 bonded to a surface 503 between the flange ends 501A, 501B. The porous ingrowth material 502 is heat-bonded to the surface 503 of the bonded insert assembly 500. After heat-bonding, the bonded insert assembly 500 can be separated at a parting line L to form two individual bonded inserts, each having one flange end 501A, 501B. It should be appreciated that the bonded inserts 110 provided in accordance with the present disclosure can thus be rapidly manufactured to further reduce the amount of time required to fabricate an implant in accordance with the present disclosure.

[0022] 6, in some embodiments, the bare portion 611 of the bonded insert 610 is fully or partially tapered to have a variable thickness T along the width W of the bare portion 611. Such a shape can aid in, for example, thermal bonding of the insert 610 to an uneven surface, which is relatively difficult to achieve using previously known methods. Thus, the present disclosure also provides a method for forming multiple implants having different shapes that is less difficult and less costly than known methods.

[0023] 7, there is shown an exemplary embodiment of another bonded insert 710 that may be used to form an implant. As can be seen, the bonded insert 710 does not have a flanged end like the bonded insert 110 described above, but instead has a shoulder 711 between the portion 712 of the insert 710 that is bonded to the porous ingrowth material 713 and the bare portion 714 of the insert 710 that is disposed within the opening 721 in the material 722 of the implant body 720. It should be understood that the implant body 720 shown is exemplary only, and that the bonded insert 710 may be used to form a variety of different orthopedic implants and / or components of orthopedic implants, including, but not limited to, total knee implant femoral components, total knee implant tibial components, partial knee implant components, glenoid implants, etc. A shoulder 711 may be formed, for example, at the interface between the bonded portion 712 of the porous ingrowth material 713 and the bare portion 714, where the width is increased relative to the bare portion 714 based on the bonded porous ingrowth material 713. The bare portion 714 of the insert 710 is heat bonded to the material 722 of the implant body 720, and the porous ingrowth material 713 may cover the opening 721 after heat bonding, similar to the bonded inserts described above. In some embodiments, the bare portion 714 of the insert 710 may have threads 715 that threadably engage with corresponding threads 723 of the opening 721 to form a mechanical fastener prior to heat bonding the bare portion 714 to the implant body 720.

[0024] Referring to FIGS. 8-10, in some exemplary embodiments, orthopedic implants 800, 900, 1000 are provided that include complex components 810, 910, 1010 having one or more complex outer surfaces 811, 911, 1011 coupled to implant bodies 820, 920, 1020. As used herein, a "complex outer surface" is an outer surface that is not perpendicular or parallel to a corresponding surface of the opposite implant body 820, 920, 1020 and that complicates the component 810, 910, 1010. In the embodiment shown in FIG. 8, for example, the complex outer surface 811 is a tapered surface that is not parallel and / or perpendicular to a surface 821, which may be the bottom surface of the implant body 820, located on the opposite side. Based on the complex outer surface 811 that is complex and not parallel or perpendicular to the surface 821 located on the opposite side, it is extremely difficult to adhere the complex component 810 to the implant body 820 using conventional methods that typically include clamping. This is because there is little surface area for clamping to press the complex component 810 and the implant body 820 together for engagement. In some embodiments, the complex components 810, 910, 1010 have a solid material, i.e., a material having a porosity of less than 10%. However, it should be understood that the complex components 810, 910, 1010 may additionally or alternatively have a porous ingrowth material that forms the component 810, 910, 1010 and / or is adhered to the component as a separate porous layer 813, 913, 1013 as shown.

[0025] To address issues with known methods of forming an orthopedic implant 800, a complex component 810 may be placed in contact with at least one adhesive surface of an implant body 820, shown as two adhesive surfaces 822, 823, and heat-bonded to the adhesive surfaces 822, 823 to bond the complex component 810 to the implant body 820. As shown, the adhesive surfaces 822, 823 may be part of an extension, shown as a post 824, extending from the implant body 820. The complex component 810 may be formed with a machined opening 812, for example, extending through the complex outer surface 811 and defining an opening width OW3 approximately the same as, or otherwise slightly smaller than, the width PW of the post 824. The complex component 810 may be fitted over the implant body 820 such that the post 824 is located within the aperture 812, which in some embodiments may have threads 814 formed therein that mate with corresponding threads 825 on the post 824 to form a mechanical bond. Once the complex component 810 is in place, with the post 824 positioned within the aperture 812, with or without a press fit or other mechanical bond, the complex component 810 and implant body 820 may be thermally bonded together, firmly bonding the complex component 810 to the implant body 820. In this regard, both the complex component 810 and the implant body 820 may be formed separately using conventional fabrication methods such as machining and then bonded together using thermal bonding.

[0026] While implant body 820 is shown and described as including post 824 with bonding surfaces 822, 823, it should be understood that in some embodiments, complex component 810 includes an extension, such as a post, and implant body 820 includes an opening into which the extension is disposed prior to thermal bonding. Alternatively, complex component 810 and / or implant body 820 may include multiple openings and / or extensions that mate with one another prior to thermal bonding. Furthermore, while orthopedic implant 800 shown in FIG. 8 is shown in the embodiment of a shoulder implant, other types of orthopedic implants may similarly be fabricated in accordance with the present invention, including, but not limited to, total knee implants, partial knee implants, tibial implants, etc. Thus, it should be understood that a variety of different orthopedic implants may be fabricated in accordance with the present invention, including a porous ingrowth material having at least one complex outer surface.

[0027] With particular reference to Figure 9, another exemplary embodiment of an orthopedic implant 900 provided in accordance with the present invention is shown, including a complex component 910 with a complex outer surface 911 that is curved rather than tapered. Figure 10 shows an orthopedic implant 1000 including a complex component 1010 with a similarly curved complex outer surface 1011, but inverted compared to the complex component 910. Similar to the complex component 810 described above, the complex components 910, 1010 may also include solid and / or porous ingrowth materials that may be bonded to the complex component 910, 1010 as the porous layers 913, 1013 described above. Both orthopedic implants 900, 1000, similar to the orthopedic implant 800 described above, can be fabricated by placing an extension, shown as a post 924, 1024, of each implant body 920, 1020 into an opening 912, 1012 formed, i.e., machined, in the complex component 910, 1010, with or without a thread, thereby contacting the complex component 910, 1010 with one or more bonding surfaces 922, 923, 1022, 1023 of the implant body 920, 1020, which may be part of the extension 924, 1024, and thermally bonding the complex component 910, 1010 to the bonding surfaces 922, 923, 1022, 1023.

[0028] 9 and 10, due to the curvature of the complex outer surfaces 911, 1011, it would be extremely difficult to form the orthopedic implants 900, 1000 using known manufacturing methods, including clamping. In contrast, forming the orthopedic implants 900, 1000 in accordance with the present invention is relatively easy and therefore economical, and reliably produces orthopedic implants 900, 1000 having acceptable strength values for implantation. It should thus be appreciated that many different types of orthopedic implants may be economically fabricated in accordance with the present invention.

[0029] 11 , there is shown one exemplary embodiment of a method 1100 for forming any of the above-described orthopedic implants 800, 900, 1000, etc., provided in accordance with the present invention. The method 1100 includes placing 1101 a porous ingrowth material 810, 910, 1010 having at least one complex outer surface 811, 911, 1011 in contact with at least one bonding surface 822, 823, 922, 923, 1022, 1023 of an implant body 820, 920, 1020. The bonding surface 822, 823, 922, 923, 1022, 1023 may be part of an extension of a post 824, 924, 1024, etc., and may be disposed 1101 within a respective opening 812, 912, 1012 formed in the porous ingrowth material 810, 910, 1010. To bond the porous ingrowth material 810, 910, 1010 to the implant body 820, 920, 1020, the porous ingrowth material 810, 910, 1010 is heat bonded 1102 to the bonding surface 822, 823, 922, 923, 1022, 1023 to form the orthopedic implant 800, 900, 1000. As described above, the complex outer surface 811, 911, 1011 may be a tapered and / or curved surface.

[0030] While the orthopedic implants described above include porous ingrowth materials, exemplary embodiments provided by the present invention may be provided without the porous ingrowth material. With particular reference to Figures 12-14, one exemplary embodiment of an orthopedic implant 1200 is shown, including an implant body 1210 and a mating part 1220 bonded to the implant body 1210. While the implant body 1210 and mating part 1220 are shown in the form of a shoulder implant, it should be understood that the orthopedic implant may also be formed as other types of implants, such as a total knee implant or a partial knee implant.

[0031] The implant body 1210 has a surface 1211 with an opening 1212 formed therein. The implant body 1210 may be formed by any suitable manufacturing method, such as, but not limited to, casting and / or machining. The opening 1212 may be formed in the surface 1211, for example, by machining. The opening 1212 is defined by a plurality of walls 1213A, 1213B, which may extend from a bottom surface 1214 that defines the bottom of the opening 1212. In other words, the opening 1212 has a closed bottom rather than an open-bottom opening that extends entirely through the implant body 1210. 13 and 14 , the walls 1213A, 1213B may extend perpendicularly from a bottom surface 1214 that may be parallel to the surface 1211 in which the opening 1212 is formed, i.e., the walls 1213A, 1213B extend perpendicularly to both the surface 1211 of the implant body 1210 and the bottom surface 1214 of the opening 1212. The opening 1212 is shown as having a D-shaped perimeter formed by the walls 1213A, 1213B, with some flat walls 1213A and some curved walls 1213B. However, it should be understood that the opening 1212 may be formed in any shape suitable for thermally bonding the mating part 1220 to the implant body 1210, as described further herein.

[0032] The mating part 1220 has an adhesive portion 1221 that is disposed within the opening 1212 and heat-bonded to the implant body 1210 to form the orthopedic implant 1200. The mating part 1220 may be formed by any suitable method, such as, but not limited to, casting and / or machining. As can be seen in FIG. 12 , the adhesive portion 1221 has a shape similar to the opening 1212. The peripheral wall 1222 of the adhesive portion 1221 may be adjacent to and / or contact the walls 1213A, 1213B that define the opening 1212 when the adhesive portion 1221 is disposed within the opening 1212. In some embodiments, the adhesive portion 1221 is shaped and dimensioned such that the entire peripheral wall 1222 is in contact with the walls 1213A, 1213B that define the opening 1212 when the adhesive portion 1221 is disposed within the opening 1212. To bond the mating parts 1220 to the implant body 1210, the material of the peripheral wall 1222 is heat bonded to the material of the walls 1213A, 1213B to form the orthopedic implant 1200. Heat bonding may include, for example, diffusion bonding and / or sintering.

[0033] In some embodiments, mating part 1220 has a post assembly including a post 1223 extending from adhesive portion 1221. Post 1223 may, for example, extend perpendicularly from adhesive portion 1221 and may have a cylindrical shape. Mating part 1220 may have no porous ingrowth material at all, i.e., no porous ingrowth material bonded to mating part 1220, or alternatively, may have one or more portions (shown in dashed lines), such as post 1223, to which porous ingrowth material 1224 is bonded. If porous ingrowth material 1224 is included, it may also be heat bonded to mating part 1220.

[0034] In some cases, additional adhesive strength may be desired between the parts forming the orthopedic implant. Referring to Figures 15, 16A, and 16B, another exemplary embodiment of an orthopedic implant 1500 provided in accordance with the present invention is shown. The orthopedic implant 1500 includes an implant body 1510 and a mating part 1520 having an adhesive portion 1521 heat-bonded to the implant body 1510. The illustrated mating part 1520 is the same as the mating part 1220 described above and may include a post assembly having, for example, a post 1523.

[0035] 16A and 16B , the implant body 1510 itself is shown in enlarged detail. Similar to the implant bodies described above, the implant body 1510 has a surface 1511 with an opening 1512 formed therein. An adhesive portion 1521 of a mating part 1520 is disposed within the opening 1512 and heat-bonded to the implant body 1510. Unlike the implant bodies described above, which were shown and described with an opening defining a constant opening width, the opening 1512 is defined by a plurality of walls 1513A, 1513B that may extend non-perpendicularly from a bottom surface 1514, thereby defining a variable opening width OW4 that may vary based on the distance from the bottom surface 1514. The wall 1513A may be continuous with the bottom surface 1514, and the wall 1513B may be continuous with the wall 1513A and define the surface 1511 in which the opening 1512 is formed.

[0036] The opening width OW4 may be a first value at a first distance from the bottom surface 1514 that is substantially zero, i.e., the first value of the opening width OW4 is defined at the bottom surface 1514. The opening width OW4 at the first distance may be smaller than the opening width OW4 at a second distance from the bottom surface 1514 that is greater than the first distance. This can be particularly seen in FIG. 16A , where the wall 1513A extends such that the opening width OW4 increases with increasing distance from the bottom surface 1514. The opening width OW4 may increase to a maximum value at a second distance from the bottom surface 1514 where the walls 1513A and 1513B meet. The opening width OW4 may then decrease at a third distance from the bottom surface 1514, corresponding to the wall 1513B extending greater than the second distance and such that the opening width OW4 decreases with increasing distance from the bottom surface 1514. An undercut 1515 may be formed at the junction of the walls 1513A, 1513B, i.e., at a position between the second distance and the third distance from the bottom surface 1514, and the undercut 1515 represents a transition region between the opening width OW4, which increases as the distance from the bottom surface 1514 increases, and the opening width OW4, which decreases.

[0037] Forming the undercuts 1515 in the implant body 1510 allows for a mechanical bond to be formed during thermal bonding of the mating part 1520 and the implant body 1510. During diffusion bonding, for example, due to relatively high temperatures and pressures, material from the bonded portion 1521 of the mating part 1520 tends to deform into the walls 1513A, 1513B of the implant body 1510 without significant liquefaction of the material in the bonded portion 1521. As the material deforms into the walls 1513A, 1513B, it tends to fill the pre-formed undercuts 1515. Because opening width OW4 decreases past undercut 1515 and further from bottom surface 1514, i.e., closer to surface 1511, material that deforms from bond 1521 into undercut 1515 will form an interference fit between bond 1521 and wall 1513B, making it more difficult to pull mating part 1520 out of opening 1512. Thus, by forming undercut 1515 in implant body 1510, orthopedic implant 1500 can be formed with both thermal and mechanical bonds between implant body 1510 and mating part 1520, enhancing the bond between implant body 1510 and mating part 1520.

[0038] 17-19, another exemplary embodiment of an orthopedic implant 1700 provided in accordance with the present invention is shown. The orthopedic implant 1700 includes an implant body 1710 having a surface 1711 with a variable width opening 1712 formed therein, and a mating part 1720 having an adhesive portion 1721 disposed within the opening 1712 and heat-bonded to the implant body 1710. The mating part 1720 may be the same as the mating parts 1220 and 1520 described above and may include a post assembly having a post 1723.

[0039] The opening 1712 may be defined by a plurality of walls 1713 extending from a bottom surface 1714 that defines a bottom of the opening 1712. As shown in particular in FIG. 18 , the walls 1713 may extend from the bottom surface 1714 such that the opening 1712 defines an opening width OW5 that decreases with increasing distance from the bottom surface 1714. In other words, the opening width OW5 may be greater at a first distance from the bottom surface 1714 than at a second distance from the bottom surface 1714 that is greater than the first distance. The opening width OW5 may decrease at a constant rate, i.e., at a constant angle, with increasing distance from the bottom surface 1714, or may decrease at a variable rate.

[0040] 18 , it is shown that the adhesive portion 1721 of the mating part 1720 can contact at least one wall 1713 when positioned within the opening 1712. As shown, the contact between the adhesive portion 1721 and the wall 1713 can be adjacent to the surface 1711 of the implant body 1710 where the opening width OW5 can be smallest. The adhesive portion 1721 can define a consistent width and can define a variable separation distance SD from the wall 1713 when positioned within the opening 1712. The variable separation distance SD can vary, for example, within a range of 0.0001 inches to 0.125 inches, such as 0.005 inches to 0.020 inches, inclusive. While the variable separation distance SD is illustrated and described as being based on a variable opening width OW5 and a constant width of the adhesive 1721, in some embodiments the adhesive 1721 has a variable width that adjusts or provides a variable separation distance between the adhesive 1721 and the wall 1713.

[0041] By providing a variable separation distance SD between the wall 1713 defining the opening 1712 and the adhesive portion 1721, an interference fit can be formed between the implant body 1710 and the mating part 1720 during thermal bonding. Referring specifically to FIG. 19 , which shows the orthopedic implant 1700 after the mating part 1720 has been thermally bonded to the implant body 1710, material has deformed from the adhesive portion 1721 into the gap between the adhesive portion 1721 and the wall 1713, filling the gap. Due to the opening width OW5 of the opening 1712, which decreases with increasing distance from the bottom surface 1714, i.e., toward the surface 1711, an interference fit is formed between the deformed material of the adhesive portion 1721 and the wall 1713, making it more difficult to pull the mating part 1720 out of the opening 1712. Maintaining the separation distance SD at, for example, 0.125 inches or less ensures that the material of the bonded portion 1721 deforms sufficiently to contact the wall 1713, forming an interference fit. Thus, the orthopedic implant 1700 has a mating part 1720 that is both thermally bonded and mechanically secured to the implant body 1710, increasing the bond strength between the mating part 1720 and the implant body 1710.

[0042] 20 , one exemplary embodiment of a method 2000 for forming an orthopedic implant 1500, 1700 provided in accordance with the present invention is shown. The method 2000 includes placing 2001 adhesive portions 1521, 1721 of mating parts 1520, 1720 into openings 1512, 1712 formed in the implant body 1510, 1710, the openings defining variable opening widths OW4, OW5. The adhesive portions 1521, 1721 are thermally bonded 2002 to the implant body 1510, 1710 to bond the mating parts 1520, 1720 to the implant body 1510, 1710 to form the orthopedic implant 1500, 1700. In some embodiments, the thermal bonding 2002 includes diffusion bonding. In some embodiments, the implant body 1510 has an undercut 1515 formed therein as described above, and the material of the adhesive portion 1521 flows into the undercut 1515 during thermal bonding 2002, forming an interference fit between the adhesive portion 1521 and the walls 1513A, 1513B defining the opening 1512.

[0043] While this invention has been described with respect to at least one embodiment, it may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the scope of the appended claims.

Claims

1. 1. A method of forming an orthopedic implant, comprising: heat bonding the porous ingrowth material to the surface of the insert to form a bonded insert; placing the bare portion of the bonded insert into a recess formed in the material of the implant body; and heat bonding the bare portion to the material of the implant body to bond the bonded insert to the implant body. Including, the recess has an opening and a closed bottom surface on the vertical opposite side of the opening, the bare portion has at least one flange, the opening defines an opening width, the flange defines a flange width greater than the opening width, and the flange is entirely positioned within the recess when the bare portion and the material of the implant body are thermally bonded together. A method for forming an orthopedic implant.

2. The method of claim 1 , wherein thermal bonding of the bare portion comprises diffusion bonding the bare portion to the material of the implant body.

3. The method of claim 1 , wherein thermal bonding the bare portion comprises sintering the bare portion to the material of the implant body.

4. The method of claim 1 , wherein the recess is defined by the bottom surface and a plurality of walls extending from the bottom surface.

5. The method of claim 4 , wherein the wall extends perpendicularly from the bottom surface.

6. The method of claim 1 , wherein the porous ingrowth material of the bonded insert covers the opening when the bare portion is placed within the recess.

7. The method of claim 1 , further comprising forming an opening pattern in the implant body that includes the recess.

8. 1. An orthopedic implant comprising: an implant body having a surface with a recess formed therein; a bonded insert disposed within the recess and having a bare portion heat-bonded to the implant body and a bonded portion bonded to the bare portion; and a porous ingrowth material bonded to said adhesive joint; Including, the recess has an opening and a closed bottom surface on the vertical opposite side of the opening, the bare portion has at least one flange, the opening defines an opening width, the flange defines a flange width greater than the opening width, and the flange is entirely positioned within the recess when the bare portion and the material of the implant body are thermally bonded together. Orthopedic implants.

9. The orthopaedic implant of claim 8 , wherein the porous ingrowth material covers the opening.

10. The orthopaedic implant of claim 8 , wherein the recess is defined by a bottom surface and a plurality of walls extending from the bottom surface.

11. The orthopaedic implant of claim 10 , wherein the wall extends perpendicularly from the bottom surface.

12. 9. The orthopaedic implant of claim 8, wherein the implant body has a plurality of said recesses, and the orthopaedic implant has a plurality of bonded inserts each having a respective one of said bare portions disposed within said opening of a respective one of said recesses.

13. 1. An orthopedic implant comprising: an implant body having a surface with a recess formed therein; a bonded insert disposed within the recess and having a bare portion heat-bonded to the implant body and a bonded portion bonded to the bare portion; and a porous ingrowth material bonded to said adhesive joint; Including, the recess has an opening and a closed bottom surface on the vertical opposite side of the opening, the porous ingrowth material is configured to cover the opening when the bare portion is disposed within the recess; the bare portion has at least one flange, the opening defines an opening width, the flange defines a flange width greater than the opening width, and the flange is entirely positioned within the recess when the bare portion and the material of the implant body are thermally bonded together. Orthopedic implants.

Images