WO2023064330A1 - Porous implant surfaces - Google Patents

Abstract

In various examples, the present disclosure pertains to methods of forming porous regions on ceramic oxide surfaces of zirconium- containing medical device components. In these methods, the porous regions are formed by a process that comprises (a) using laser beam (220) surface texturing or electron beam surface texturing to create one or more beam-textured regions (240) in one more ceramic oxide surfaces of a zirconium-containing component of a medical device and, optionally, (b) subjecting the one or more beam-textured regions to a secondary oxidation process. In some examples, such porous regions are produced by electrolytic oxidation process alone.

Description

POROUS IMPLANT SURFACES

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This PCT application claims the benefit of the filing date of pending U.S. provisional patent application number 63/255,498, filed October 14, 2021, entitled “Porous Implant Surfaces,” the entirety of which application is incorporated by reference herein.

FIELD OF THE DISCLOSURE

[0002] The present disclosure is directed to methods of forming porous regions on surfaces of implantable devices and to implantable devices that are formed using such methods.

BACKGROUND

[0003] The wrought forged components typically used in current generation total joint arthroplasty are fabricated from an alloy of 97.5% zirconium and 2.5% niobium (Zr-2.5Nb). They are oxidized in air at temperatures above 500°C. Thermal diffusion in an oxygen-rich environment, referred to hereafter as thermal graded oxidation (TGO), creates a hard implantable oxidized surface with a thickness of approximately 5 pm. An example of such a material is OXINIUM™ Oxidized Zirconium, OxZr (Smith and Nephew Inc., Memphis TN, USA). The thermal diffusion process forms a uniform oxide even on complex-shaped components such as a femoral component of a total knee replacement, with a gradual transition from the surface ceramic oxide to substrate Zr-2.5Nb.

[0004] The resulting black ceramic oxide surface is an integral part of the material, as opposed to a surface coating, which is characterized by a weak coating-substrate interface, especially under mechanical strain and bending deformation. The ceramic surface of OxZr caused by its chemical bond to the underlying substrate is also less susceptible to debonding or chipping than nitrogen- ion-implanted Ti-6A1-4V surfaces.

[0005] In total knee arthroplasty (TKA), OxZr is used in the femoral component of the prosthesis due to its unique properties of having a ceramic surface with the ductility of a metallic component. Consequently, OxZr reduces the incidence of abrasive and adhesive wear mechanisms and the accompanying release of debris. Currently, OxZr femoral components rely on cemented fixation whereby horizontal splines located on the inside bone contacting surface are able to trap bone cement such as poly methyl methacrylate (PMMA), to facilitate mechanical fixation of the femoral component with bone.

[0006] Cementless fixation in TKA has gained more and more popularity as a better alternative to cemented fixation. To promote biological bone ingrowth, the inner side of the femoral component, i.e., the surface that is in contact with the bone, has a porous surface with porous characteristics as per Food and Drug Administration (FDA) requirements (see, e.g., FDA Guidance Document 1418, “Class II Special Controls Guidance Document: Knee Joint Patellofemorotibial and Femorotibial Metal/Polymer Porous-Coated Uncemented Prostheses; Guidance for Industry and FDA”, issued Jan 16, 2003).

[0007] The traditional approach to creating porous surfaces on orthopedic implants utilizes porous bead or wire structures, which are sintered at high-temperature. However, sintering (at ~1100°C) after the oxidation step changes the parent material as well as OxZr microstructure and can result in a loss of fatigue strength, oxide integrity issues and mottled or non-uniform oxide. If sintering of the porous structure occurs before TGO, grain growth can cause a mottled appearance of the oxide, and loss of fatigue strength. If sintering of the porous structure occurs after TGO, the microstructure created is a wavy, non-uniform oxide, which can have oxide integrity issues and loss of fatigue strength. Consequently, in order to avoid degrading the unique characteristics of

OxZr, alternatives to high temperature sintering are desired. [0008] Thermal porous plasma spraying (PPS) is a low-temperature coating process used to create in-growth surfaces for cementless fixation. Plasma spray coatings applied to joint replacement prostheses are designed to encourage new bone formation around an implant, thereby improving fixation and long-term survivorship of the artificial joint. The thermal porous plasma spray process utilizes melted (or heated) materials, i.e., "feedstocks" (coating precursors), which are sprayed directly onto a surface using a plasma jet as the energy carrier, which is produced by establishing a DC (direct current) arc between the electrode (cathode) and the nozzle (anode) with partial or total ionization of the plasma gas occurring. The plasma gases commonly used are argon, hydrogen, helium, nitrogen, or mixtures thereof. By controlling the plasma gas composition, its thermal conductivity and viscosity can be adjusted. The plasma jet heats the spray material, which may be injected into the plasma jet inside or outside the nozzle. The high velocity of the jet emerging from the nozzle and acceleration of the particles is generated by the thermal expansion of the plasma.

[0009] There are, however, some disadvantages to using thermal porous plasma spraying for creating porous ingrowth surfaces. Firstly, it requires a line of sight to the surface being coated, similar to all other thermal spraying processes making it challenging to coat inner surfaces of small diameter bores and other restricted access surfaces. The process is particularly challenging for parts with complex geometry, such as femoral components, which have special features that would block the line of sight, such as femoral pegs. Further, femoral components may have 4 or 5 faces that need coating with a uniform thickness. Most of the faces are inclined at different angles, which makes spraying inside a femoral component and maintaining uniform coating thickness difficult. The size of the femoral components to be coated is another challenge, with smaller size of the femoral components preventing the spray gun from spraying all the inner surfaces. There is also a low degree of adhesion (spray efficiency) on small substrates and substrates with small radii of curvature. Brittleness, hardness, anisotropic properties and residual stresses can occur, which is the result of very rapidly cooled and flattened particles. The porosity of the coatings is also difficult to control due to the chaotic process associated with the buildup of the thermal spray coating. Particles overheated in the spray jet can become oxidized, and non-melted particles may simply be embedded in the accumulating deposit, which can lead to particle shedding.

[0010] It is with this in mind that the present disclosure is provided. The methods herein provide a transformative process (re-melting and casting) to form integral porous regions having many structural patterns on ceramic oxide surfaces of zirconium-containing components of medical devices.

SUMMARY

[0011] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter.

[0012] In various examples, the present disclosure pertains to methods of forming porous regions on ceramic oxide surfaces of zirconium-containing components of medical devices. In these methods, the porous regions are formed by a process that comprises (a) using laser beam surface texturing or electron beam surface texturing to create one or more beam-textured regions in one more ceramic oxide surfaces of a zirconium-containing component of a medical device and, optionally, (b) subjecting the one or more beam-textured regions to a secondary oxidation process. Alternatively, in some examples, the present disclosure pertains to methods of forming one or more porous regions on ceramic oxide surfaces of zirconium-containing components of medical devices by masking one or more regions of the medical device and treating the device by an oxidation process to selectively create one or more porous regions in one more ceramic oxide surfaces of a zirconium-containing component of the medical device. [0013] In any preceding or subsequent example, one or more porous regions are formed on one more ceramic oxide surfaces of a pure zirconium component.

[0014] In any preceding or subsequent example, one or more porous regions are formed on one more ceramic oxide surfaces of a zirconium alloy component. Examples of zirconium alloys include those that comprise zirconium and one or more biocompatible elements such as niobium, titanium, molybdenum, silver, manganese or tantalum, among others.

[0015] In any preceding or subsequent example, one or more porous bone ingrowth regions may be formed on one more bone-interfacing ceramic oxide surfaces of a zirconium-containing component of an implantable device. Examples of implantable devices that can be treated using such methods include knee implants, hip implants, shoulder implants, ankle implants, spinal implants, trauma implants, mid-shaft implants, arthrodesis implants, UniSpacers, and cartilage replacements, among others. In particular examples, one or more porous bone ingrowth regions are formed on bone-interfacing ceramic oxide surfaces of a zirconium-containing femoral implant body (e.g., a femoral implant body configured for use in a total knee arthroplasty).

[0016] In any preceding or subsequent example, the ceramic oxide surface may be formed on the zirconium-containing component by thermal diffusion at elevated temperature in an oxy genrich environment.

[0017] In any preceding or subsequent example, laser beam texturing and/or electron beam texturing is performed such that an initial porous region is formed on the surface of the zirconium- containing component, wherein one or more of the following types of features are formed: bladelike protrusions, columnar protrusions, blind hole-type intrusions, blind slot-type intrusions, penetrating hole-type intrusions, penetrating slot-type intrusions, shaped protrusions of high aspect ratio in one elevation, curved blade-like protrusions, multi-faceted protrusions, angled protrusions, multi-faceted (i.e., intersecting) slot-type intrusions, curved intrusions, slot-type intrusions, and angled intrusions. [0018] In any preceding or subsequent example, laser beam texturing and/or electron beam texturing is performed such that an initial porous region is formed on the surface of the zirconium- containing component. In these examples, a porous region may be formed which has a 30-60% volume fraction of porosity, beneficially, a 50-60% volume fraction of porosity, a mean pore diameter ranging from 20 to 800 microns, and a coating thickness ranging from 20 to 2000 microns, among other values. In some examples, the porous regions are formed to meet FDA requirements for porous structures, including, for example, a porosity greater than 30% volume fraction, a mean pore size ranging from 100 to 100 microns and a coating thickness ranging from 500 to 1500 microns. Obtaining these values depend on the laser bean power (60 - 80 mW), average pulse energy (60 - 80 pj), average fluence (0.05 - 0.8 J/cm²), repetition rate (1 - 1000 Hz), scanning speed (1-20 mm/s), number of laser pulses (2-1069), lateral displacement (0.09-0.2 mm) and the processing atmosphere (air, Ar).

[0019] In any preceding or subsequent example, the secondary oxidation process is an electrolytic oxidation process, for example, a plasma electrolytic oxidation (PEO) process.

[0020] In any preceding or subsequent example, an existing porosity of the beam-textured surface is increased by the secondary oxidation process. For example, the secondary oxidation process may be used to form a porous region which has an average porosity ranging from a 30- 80% volume fraction of porosity, beneficially, a 70 to 80% volume fraction of porosity, a mean pore diameter ranging from 600 to 900 microns, and a thickness ranging from 1000 to 2000 microns, among other values.

[0021] In any preceding or subsequent example, the secondary oxidation process may be used to form a porous region having an oxide surface layer that ranges from 1000 to 2000 microns in thickness.

[0022] In any preceding or subsequent example, the secondary oxidation process may be used to incorporate an additional substance into the porous region. In some of these examples, the additional substance is a compound comprising calcium and phosphorous, for example, a calcium phosphate compound such as hydroxyapatite, among others. In some of these examples, the additional substance enhances the bioactivity of the porous region.

[0023] In any preceding or subsequent example, one or more surface areas of the zirconium- containing component are masked during the secondary oxidation process to preserve the characteristics of the ceramic oxide layer (e.g., bearing surfaces of an implant body may be masked). After the secondary oxidation process is completed, the masking material is removed. [0024] Exemplary embodiments of the present disclosure provide numerous technological advantages and technical features over conventional systems. For example, one non-limiting technological advantage may include the ability to provide porous regions on zirconium-containing components, without the need for heating to high temperatures that degrade the properties of the zirconium-containing component. Another non-limiting technological advantage may include the ability to provide porous regions on zirconium-containing components, without the need for thermal spraying processes, which can lead to a low tensile adhesion strength, poor porosity control and/or a non-uniform coating thickness . Another non-limiting technological advantage may include the ability to provide bioactive porous regions on zirconium-containing components promoting durable long-term biologic fixation.

[0025] In further examples of the disclosure, the methods herein produce an implantable medical device with one or more porous regions in one or more ceramic oxide surfaces of a zirconium-containing component surface of said implantable device.

[0026] In any preceding or subsequent example, the implantable medical device is selected from femoral implants, knee implants, hip implants, shoulder implants, ankle implants, spinal implants, trauma implants, mid-shaft implants, arthrodesis implants, UniSpacers, or cartilage replacements, among others. [0027] Further features and advantages of at least some of the exemplary embodiments of the present invention, as well as the structure and operation of various exemplary embodiments of the present invention, are described in detail below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] By way of example, specific examples of the disclosed methods, systems, and apparatuses will now be described, with reference to the accompanying drawings, in which:

[0029] FIG. 1 depicts a femoral component , in accordance with an example of the present disclosure.

[0030] FIG. 2 depicts a process of laser surface texturing, in accordance with an example of the present disclosure.

[0031] FIG. 3A schematically depicts how a laser beam can enable protrusions to be built and shaped in separate operations. FIG. 3B is an electron micrograph showing a protrusion formed by laser texturing.

[0032] FIG. 4 illustrates various patterns that can be created using laser assisted texturing.

[0033] FIG. 5 A is a cross-sectional view of a laser-textured Zr-2Nb alloy surface, in accordance with an example of the present disclosure.

[0034] FIGS. 5B and 5C are images of electron beam-textured Oxinium coupons illustrating different density porous structures.

[0035] FIGS. 6 A and 6B depict porous network structures that are produced by additive manufacturing processes.

[0036] FIG. 7 schematically illustrates a metal implant body immersed in an electrolyte, in accordance with an example of the present disclosure.

[0037] FIGS. 8A-8C are images of a titanium surface in which surface topography is created by a secondary PEG process. [0038] FIG. 9 schematically illustrates a process of forming a femoral implant in which a laser texturing process is used to create a porous surface, in accordance with an example of the present disclosure.

[0039] FIGS. 10A and 10B are schematic illustrations of a cross-section of a laser textured surface after PEG treatment, in accordance with an example of the present disclosure.

DETAILED DESCRIPTION

[0040] Various features or the like of implantable devices and methods of forming the implantable devices will now be described more fully hereinafter with reference to the accompanying drawings, in which one or more features of the implantable devices and methods will be shown and described. It should be appreciated that the various features may be used independently of, or in combination, with each other. It will be appreciated that implantable devices and methods as disclosed herein may be embodied in many different forms and should not be construed as being limited to the examples set forth herein. Rather, these examples are provided so that this disclosure will convey certain features of the implantable devices and methods to those skilled in the art.

[0041] In various examples, the present disclosure pertains to methods for forming porous regions on ceramic oxide surfaces of zirconium-containing components of implantable devices. For example, in some examples, one or more porous bone ingrowth regions may be formed on one more bone-interfacing ceramic oxide surfaces of a zirconium-containing component of an implantable device.

[0042] Examples of implantable devices that can be made using such methods include knee implants, hip implants, shoulder implants, ankle implants, spinal implants, trauma implants, midshaft implants, arthrodesis implants, UniSpacers, and cartilage replacements, among others. [0043] In some examples, one or more porous regions are formed on one more ceramic oxide surfaces of a pure zirconium component of a medical device. In some examples, one or more porous regions are formed on one more ceramic oxide surfaces of a zirconium alloy component of a medical device. Examples of zirconium alloys include those that comprise zirconium and one or more biocompatible elements such as niobium, titanium, molybdenum, silver, manganese or tantalum, among others (e.g., Zr-Nb, Zr-Ti, Zr-Mo, Zr-Ta, Zr-Zr-Nb-Zn, Zr-Mo-Zn, Zr-Nb-Ti, and Zr-Al-Fe-Nb alloys), with an alloy of 97.5% zirconium and 2.5% niobium (Zr-2.5Nb) being a particular example.

[0044] The ceramic oxide surface may be formed on the zirconium-containing component, for example, by thermal diffusion at elevated temperature in an oxygen-rich environment. In certain beneficial examples, the zirconium-containing component is fabricated from an alloy of 97.5% zirconium and 2.5% niobium (Zr-2.5Nb alloy) having a ceramic oxide surface, such as an OXINIUM™ Oxidized Zirconium implant body, in which the ceramic oxide surface is formed in air at temperatures above 500°C.

[0045] In certain examples, the zirconium-containing component corresponds to an implant body and the one or more porous regions correspond to one or more porous bone ingrowth regions of the implant body. One particular example of a zirconium-containing implant body is femoral implant body 5, like that shown in FIG. 1. The bone-interfacing ceramic oxide surfaces of the femoral implant body 5, in which porous regions can be formed, include two posterior flat surfaces (25) (one shown), two posterior chamfer surfaces (26) (one shown), one or two distal flat surfaces (27) (one shown), an anterior chamfer surface (28), an anterior flange surface (29), and two pegs (30) (one shown). Also shown in FIG. 1 are a posterior articular surface (31), a distal articular surface (32), and an anterior articular surface (33).

[0046] In the methods of the present disclosure, porous regions are formed on ceramic oxide surfaces of zirconium-containing components by a process that comprises (a) using laser or electron beam surface texturing to create one or more beam-textured regions in the one more ceramic oxide surfaces and (b) subjecting the one or more beam-textured regions to a post oxidation process, for example, an electrolytic oxidation process to increase surface bioactivity. [0047] A wide variety of lasers are available including solid state lasers (e.g., ruby laser, neodymium-YAG (yttrium aluminum garnet) lasers, etc.), gas lasers (e.g., helium lasers, heliumneon lasers, CO2 lasers, etc.), excimer lasers, and dye lasers, among others. In some examples, shifted laser surface texturing (sLST) in combination with hybrid polygonal laser beam scanning systems are particularly beneficial due to increased process speed and the ability to produce surfaces with precise periodical shapes and structures at higher laser scanning speeds. sLST is a newly developed method, which has a potential to be at least 100 times more productive than traditional laser texturing with no heat accumulation effect and a virtually unlimited number of complex shape objects being producible with high precision on surfaces. In sLST, laser pulses are typically rapidly distributed across an entire surface by applying only one laser spot to one object at one repetition, with each repetition being slightly shifted on the surface and a sequence of shifts forming shapes of objects. Scanning is typically done along straight lines and laser pulsing is switched on continuously during processing of whole lines.

[0048] Laser beam texturing can generally operate under an ambient atmosphere, an inert atmosphere, a reducing atmosphere, an oxidizing atmosphere, or a vacuum, with an argon atmosphere being preferred in some examples to avoid surface oxidation. Electron beam texturing is generally operated under vacuum.

[0049] Laser beam texturing can be operated in the following regimes, among others: continuous wave (CW) mode, quasi-continuous wave (QCW) monde, single pulsed (normal mode), single pulsed Q-switched mode, repetitively pulsed mode, nanosecond (NS) pulsed mode, picosecond (PS) pulsed mode, femtosecond (FS) pulsed mode, and mode locked. Different laser beam pulse regimes (nanosecond, picosecond and femtosecond) can be used to control the size and shape of the laser-ablated structures.

[0050] FIG. 2 schematically depicts a process in which a laser or electron beam 220 is focused through a lens 225 onto a surface at an interaction region 230, which is used to produce a series of beam-textured areas 240.

[0051] FIG. 3A schematically depicts how melting and moving material using a laser or electron beam can enable protrusions to be built and shaped in separate operations. An energy beam (laser or electron beam) is used to locally melt the surface of the substrate and then to translate the molten material laterally. Multiple passes of the energy beam allow complex surface textures to be created. First an intense energy beam interacts with the surface, to distort the flat surface and create an intrusion. The energy beam is translated, and the molten material is translated laterally to form a protrusion. With several passes of the energy beam a sculpted surface is generated, with higher, taller features. In this way uniform and repeatable structure can be manufactured, with no adhesion issues of the features. FIG. 3B is an electron micrograph showing how an overall structure 340 can be built and shaped into a structure having various nodules and grooves 340g.

[0052] FIG. 4 illustrates various regular or irregular patterns of bumps, dimples, and linear or non-linear grooves that can be created by beam texturing of a either titanium 6AL-4V alloy, cobalt chrome alloy or stainless-steel hip prostheses. Porous regions 400a, 400b of a hip prosthesis 400 are schematically illustrated at the center of FIG. 4.

[0053] FIG. 5A is a cross-sectional view of a laser-textured Zr-2Nb alloy surface, highlighting a porous structure that can be created by a beam texturing process. Different porous characteristics can be generated by varying key energy beam parameters: accelerating voltage (range: 60-100 kV), beam current (range: 5 - 15 mA), beam deflection parameters i.e., pattern, amplitude gain and frequency (Hz); etc. [0054] FIG. 5B shows an Oxinium coupon with a surface texture created by electron-beam texturing to generate features (structures) with heights above 1 mm. However, the feature density was low. FIG. 5C illustrates an improved surface texture created by slightly modifying the beam deflection parameters, amplitude (mA) and frequency (Hz). Beam texturing can produce a surface texture with an average porosity of 55% ± 3%, pore size of 551 ±31 microns, and a thickness of 1150 to 1300 microns, among other values.

[0055] The beam texturing process is capable of creating the following structures, which may positively influence bone on-growth: (a) high aspect ratio blade-like protrusions (typically -15:1, height: width), (b) high aspect ratio columnar protrusions (typically -10: 1, height: width), (c) blind hole-type intrusions, (d) blind slot-type intrusions, (e) penetrating hole-type intrusions, with burr- free edges on the penetrating side, (1) penetrating slot-type intrusions, with burr-free edges on the penetrating side, (g) shaped protrusions of high aspect ratio (e.g., -10-20:1, heightwidth) in one elevation, (h) curved blade-like protrusions, (i) multi-faceted protrusions, (j) angled protrusions, (k) multi-faceted (intersecting) slot-type intrusions, (k) curved, slot-type intrusions and (1) angled intrusions.

[0056] Electron beam processing can also create features approximately 500 pm in height using a laboratory 60kV, 4kW EB (electron beam) machine.

[0057] Beam texturing has the advantage of creating uniform and repeatable structures, and superior adhesion (>20MPa per ASTM Fl 044 and ASTM Fl 147) without requiring a third material, which could potentially adversely affect biocompatibility. Beam surface texturing cannot currently achieve the size and shape of porous network structures that are produced by additive manufacturing processes, such as those shown FIGS. 6A and 6B (CONCELOC™, Smith & Nephew Inc. TN, US). However, such structures must be bonded onto the implant body using traditional high-temperature process, which makes this very challenging for oxidized zirconium alloy materials. [0058] In the present disclosure, the porosity of the beam textured surface is increased by subjecting the beam textured surface to a secondary oxidation process. In some examples, the oxidation process is an electrolytic oxidation process, such as a plasma electrolytic oxidation (PEO) process.

[0059] PEO is an electrochemical process of oxidation that is performed by creating microdischarges on the surface of components immersed in an electrolyte. FIG. 7 schematically illustrates an implant body comprising a metal substrate 710 and having a porous ceramic oxide surface 715 immersed in an electrolyte 720 that is used in conjunction with the PEO process. During PEO, plasma discharge occurs at the metal/electrolyte interface when an applied voltage exceeds a certain critical breakdown value and appears as a number of discrete short-lived micro discharges moving across the surface. This plasma discharge oxidizes the surface of the part and grows a nano-structured ceramic oxide layer from the metal substrate material. The oxide film is produced by subsurface oxidation. The oxidation may be performed at progressively higher voltages. Advanced pulsed-current techniques are available which offer the potential for further dramatic improvements in process control and flexibility. As a result, the PEO process can produce thick oxide coatings of varying porosity. The PEO treatment has the advantage of being low cost while creating a uniform coating thickness. Other advantages include; (a) minimal surface preparation, (b) application to substrates, including titanium, stainless steel, cobalt-chrome and zirconium alloys, which are shot-peened, grit-blasted, (c) formation of a hard, wear resistant surface, (d) enhanced corrosion resistance, (e) minimal impact on mechanical strength i.e., elastic modulus, of substrates, (f) flexibility in terms of strain tolerance, (g) good adhesion of the ceramic oxide layer to the underlying substrate, (h) the ability to coat inside cavities and complex shapes and (i) stable m-ZrCh and t-ZrCh phases can be formed on Zr-containing substrates.

[0060] The properties of the beam-textured surface may be enhanced by the PEO process in two ways. First, surface macropores created by the beam texturing process may be etched by the PEO process creating more asperities for bone to interdigitate within the porous surface. FIGS. 8A-8C are images highlighting the surface topographies that can be created in a standard, non- laser-ablated titanium surface using a PEO process by controlling the process parameters, with FIG. 8A showing a dense surface, FIG. 8B showing a more porous surface and FIG. 8C showing an etched surface. Microparticles of magnesium or silica can also be incorporated in PEO electrolytic solution in order to enhance the porosity of the component in order to meet the FDA requirements for a bone-ingrowth surface. These trapped particles can decompose within the oxide layer leading to increased porosity. Porosity percentages in PEO-processed, beam-textured surfaces may be in a range of 25-35% with a mean pore diameter ranging between 60-100 pm, which can be improved further by adjusting electrical and electrolyte parameters and repeating the PEO process (duplex).

[0061] Second, while the coating generated in the PEO process is principally the oxide of the underlying metal substrate, the coating can further include other species incorporated from the electrolyte. For example, the PEO process can be designed to introduce species such as Ca²⁺, Zn²⁺, P³⁺, and phosphate (PO4³ ) into standard electrolytes to create a bioactive surface. For example, the electrolyte solution can be prepared using a calcium salt (e.g., calcium acetate or another calcium salt) and a phosphate salt (e.g., glycerophosphate disodium or another phosphate salt) in water (e.g., deionized water) (Type I or Type II). Oxidizing the beam-textured, zirconium-containing components in solutions containing compounds of calcium and phosphorous can lead to the formation of bioactive layers, which may significantly reduce the time required for the osseointegration of implant to bone. HAP (hydroxyapatite) (Caio(P04)e(OH)2) is one example of a compound of calcium and phosphorus that may be formed. It is postulated that the biomimetic porous surface may dispense with the need for an additively manufactured 3D porous network, like that discussed above. [0062] In some examples, an additional substance, such as those described above, is incorporated into the porous region or as a surface coating before (or instead of) the PEO processing. Methods for incorporating these additional substances are known in the art, and include for example, coating methods disclosed in U.S Pat. No. 8,821,911 and the like.

[0063] An increase in the PEO processing voltage increases the thickness of oxide coatings that are produced and the size of the pores in the coatings. An increase in the PEO processing voltage also increases the amount of material that is introduced into the coatings from the electrolyte. An increase in the voltage frequency of the PEO processing, on the other hand, results in a reduced coating thickness and a reduced size of the largest pores, while increasing the amount of material that is introduced into the coatings from the electrolyte. Increasing the overall time of PEO treatment results in an increase in coating thickness, an increase in coating porosity, an increase in the size of the pores in the coating, and an increase in the amount of material that is introduced into the coatings from the electrolyte.

[0064] Areas of the zirconium-containing component where it is desirable retain the original thermally grown oxide layer (e.g., bearing surfaces of a zirconium-containing implant body) can be protected by either using a soft insulating mask (e.g., a mask of lacquer or wax material) or a hard insulating mask (e.g., a mask of stop-off tape, aluminium foil, glass or plastic tape or permanent masks molded from polyethylene, polypropylene, rubber or polyvinyl chloride (PVC)) to prevent plasma discharge from occurring in the masked areas during the PEO process. The PEO process parameters (e.g., the electrical regimes, electrolyte composition, processing tank geometry, etc.) can be optimized to enhance the level of inter-connected porosity and the coating thickness. After the PEO process is completed, the masking material is removed.

[0065] As seen from the preceding discussion, the present disclosure provides porous regions on ceramic oxide surfaces of zirconium-containing components of implantable devices, which have properties tailored for cementless fixation. The porous regions are created by first subjecting the ceramic oxide surface of the zirconium-containing component to a laser or electron beam texturing process to create a textured surface that can support bone in-growth. Subsequently, the beam-textured surface is subjected to a secondary oxidation process, such as a PEO process, to enhance osseointegration by increasing the degree of interconnected porosity. The secondary PEO process may also be used to create a biomimetic surface, which may have a calcium phosphate composition similar to the major inorganic component of natural bone. This may be achieved by introducing special species like Ca²⁺, Zn²⁺, P³⁺, and PO4³' into the electrolytes used in PEO to create a bioactive surface. For example, employing an aqueous electrolyte containing CsFENaOeP SFEO and (CHsCOCfhCa H2O during the PEO process (e.g., pulse voltage 250-450 V, frequency 1000 Hz, duty cycle 60%, 1-3 min) can lead to a biomimetic surface. The presence of calcium and phosphorous in the oxide layer may improve cell adhesion and proliferation and also stimulate the production of key marker proteins such as Runx2 (RUNX Family Transcription Factor 2) indicating differentiation of cells.

[0066] A specific example will now be described. In a first step, a wrought or forged Zr-2.5Nb alloy implant is heated in air above 500°C allowing oxygen to diffuse into the surface, transforming the metal surface into ceramic oxide. This creates oxy gen-enriched metal under ceramic oxide, which provides gradient properties. The ceramic oxide surface is complemented with a tough, ductile metal interior.

[0067] One or more surfaces of the implant are then subjected to a laser- or electron-beam texturing process to create one or more porous regions. As shown in FIG. 9, bone-interfacing ceramic oxide surfaces of a femoral implant 905 can be subjected to a laser- or electron-beam texturing process to create the porous regions. The bone-interfacing ceramic oxide surfaces in which porous regions can be formed include, one or two distal flat surfaces (927), an anterior chamfer surface (928), an anterior flange surface (929), two posterior chamfer surfaces (926) (a portion of one posterior chamfer surface is shown), two posterior flat surfaces (not shown), and two pegs (930). Also shown in FIG. 9 are portions of the posterior articular surface (931) and the anterior articular surface (933) which is illustrated as a glossy black ceramic oxide surface that has not been laser textured.

[0068] Critical areas of the resulting textured component, e.g., articulating surfaces, such as the posterior articular surface, the distal articular surface, and the anterior articular surface, are then masked to protect them from plasma oxidation. The unmasked portions of the component are then subjected to a PEO treatment using either a standard PEO electrolyte to provide interconnected pores 1042, as shown in FIG. 10A, or an electrolyte containing materials such as calcium- and phosphorous-containing compounds, to create interconnected pores that are doped with biomimetic materials 1044, 1046, as shown in FIG. 10B. Standard electrolytes include Na2SiC>3 orNaOH electrolyte. The functional properties of the resulting oxide coating depend on the synthesis conditions, including the electrolyte composition, the cathode and anode current densities, and the treatment time, among other factors. After the oxidation process is completed, the masking material is removed.

[0069] Stress caused by the formation and growth of the oxide film (i.e., intrinsic stress) can arise because an oxide usually has a larger volume than that of the metal from which it is formed. If the oxide maintains crystallographic coherency with the underlying metal, then the oxide is in compression, while the metal is placed in tension. It is generally recognized that compressive stresses in coatings are more favorable than tensile stresses because they increase resistance to fatigue failure.

[0070] While the preceding discussion is directed to the formation of porous regions on ceramic oxide surfaces of zirconium-containing components of implantable devices by laser or electron beam texturing followed by oxidation, in other examples, porous regions may be formed on ceramic oxide surfaces of zirconium-containing components by cold gas spraying. Cold gas spraying is a solid-state process, which is able to provide a porous zirconium oxide coating on an underlying zirconium-containing component with minimal damage to the zirconium-containing component and minimal metallurgical changes at the interface between the two dissimilar materials. In addition, cold gas spraying may be combined with PEO to meet the pore size and shape requirements per ASTM Fl 854.

[0071] While the present disclosure refers to certain examples, numerous modifications, alterations, and changes to the described examples are possible without departing from the sphere and scope of the present disclosure, as defined in the appended claim(s). Accordingly, it is intended that the present disclosure not be limited to the described examples, but that it has the full scope defined by the language of the following claims, and equivalents thereof. The discussion of any example is meant only to be explanatory and is not intended to suggest that the scope of the disclosure, including the claims, is limited to these examples. In other words, while illustrative examples of the disclosure have been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed, and that the appended claims are intended to be construed to include such variations, except as limited by the prior art. [0072] Directional terms such as top, bottom, superior, inferior, medial, lateral, anterior, posterior, proximal, distal, upper, lower, upward, downward, left, right, longitudinal, front, back, above, below, vertical, horizontal, radial, axial, clockwise, and counterclockwise) and the like may have been used herein. Such directional references are only used for identification purposes to aid the reader’s understanding of the present disclosure. For example, the term “distal” may refer to the end farthest away from the medical professional/operator when introducing a device into a patient, while the term “proximal” may refer to the end closest to the medical professional when introducing a device into a patient. Such directional references do not necessarily create limitations, particularly as to the position, orientation, or use of this disclosure. As such, directional references should not be limited to specific coordinate orientations, distances, or sizes, but are used to describe relative positions referencing particular examples. Such terms are not generally limiting to the scope of the claims made herein. Any example or feature of any section, portion, or any other component shown or particularly described in relation to various examples of similar sections, portions, or components herein may be interchangeably applied to any other similar example or feature shown or described herein.

[0073] While the present disclosure refers to certain examples, numerous modifications, alterations, and changes to the described examples are possible without departing from the sphere and scope of the present disclosure, as defined in the appended claim(s). Accordingly, it is intended that the present disclosure not be limited to the described examples. Rather these examples should be considered as illustrative and not restrictive in character. All changes and modifications that come within the spirit of the invention are to be considered within the scope of the disclosure. The present disclosure should be given the full scope defined by the language of the following claims, and equivalents thereof. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure belongs.

[0074] The foregoing description has broad application. The discussion of any example is meant only to be explanatory and is not intended to suggest that the scope of the disclosure, including the claims, is limited to these examples. In other words, while illustrative examples of the disclosure have been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed, and that the appended claims are intended to be construed to include such variations, except as limited by the prior art.

[0075] It should be understood that, as described herein, an "embodiment" or an “example” (such as illustrated in the accompanying Figures) may refer to an illustrative representation of an environment or article or component in which a disclosed concept or feature may be provided or embodied, or to the representation of a manner in which just the concept or feature may be provided or embodied. However, such illustrated embodiments or examples are to be understood as examples (unless otherwise stated), and other manners of embodying the described concepts or features, such as may be understood by one of ordinary skill in the art upon learning the concepts or features from the present disclosure, are within the scope of the disclosure. Furthermore, references to “one embodiment” or “one example” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments or examples that also incorporate the recited features.

[0076] In addition, it will be appreciated that while the Figures may show one or more examples of concepts or features together in a single example of an environment, article, or component incorporating such concepts or features, such concepts or features are to be understood (unless otherwise specified) as independent of and separate from one another and are shown together for the sake of convenience and without intent to limit to being present or used together. For instance, features illustrated or described as part of one example can be used separately, or with another example to yield a still further example. Thus, it is intended that the present subject matter covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0077] As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used herein, specify the presence of stated features, regions, steps, elements and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components and/or groups thereof.

[0078] The phrases “at least one”, “one or more”, and “and/or”, as used herein, are open-ended expressions that are both conjunctive and disjunctive in operation. The terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein. [0079] Connection references (e.g., engaged, atached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative to movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other. Identification references (e.g., primary, secondary, first, second, third, fourth, etc.) are not intended to connote importance or priority, but are used to distinguish one feature from another. The drawings are for purposes of illustration only and the dimensions, positions, order and relative to sizes reflected in the drawings atached hereto may vary.

[0080] The foregoing discussion has been presented for purposes of illustration and description and is not intended to limit the disclosure to the form or forms disclosed herein. For example, various features of the disclosure are grouped together in one or more examples or configurations for the purpose of streamlining the disclosure. However, it should be understood that various features of the certain examples or configurations of the disclosure may be combined in alternate examples or configurations. Moreover, the following claims are hereby incorporated into this Detailed Description by this reference, with each claim standing on its own as a separate example of the present disclosure.

Claims

CLAIMS A method of forming porous regions on ceramic oxide surfaces of zirconium- containing components of medical devices which comprises (a) using laser beam surface texturing or electron beam surface texturing to create one or more beam- textured regions in one more ceramic oxide surfaces of a zirconium-containing component of a medical device and, optionally, (b) subjecting the one or more beam- textured regions to a secondary oxidation process. The method of claim 1, wherein one or more porous regions are formed on one more ceramic oxide surfaces of a pure zirconium component. The method of claims 1 or 2, wherein one or more porous regions are formed on one more ceramic oxide surfaces of a zirconium alloy component The method of claim 3, wherein said zirconium alloy comprises zirconium and one or more biocompatible elements. The method of claim 4 wherein said biocompatible element is selected from the group consisting of niobium, titanium, molybdenum, silver, manganese and tantalum. The method of any one of claims 1-5, wherein one or more porous bone ingrowth regions are formed on one more bone-interfacing ceramic oxide surfaces of a zirconium-containing component of an implantable device. The method of claim 6, wherein said implantable devices are selected from the group consisting of femoral implants, knee implants, hip implants, shoulder implants, ankle implants, spinal implants, trauma implants, mid-shaft implants, arthrodesis implants, UniSpacers, and cartilage replacements.

- 23 - The method of any one of claims 1 to 5, wherein said one or more porous bone ingrowth regions are formed on bone-interfacing ceramic oxide surfaces of a zirconium-containing femoral implant body. The method of any one of claims 1 to 8, wherein said beam texturing beam texturing forms an initial porous region on the surface of the zirconium-containing component, with one or more of the following types of features: blade-like protrusions, columnar protrusions, blind hole-type intrusions, blind slot-type intrusions, penetrating hole-type intrusions, penetrating slot-type intrusions, shaped protrusions of high aspect ratio in one elevation, curved blade-like protrusions, multi-faceted protrusions, angled protrusions, multi-faceted slot-type intrusions, curved intrusions, slot-type intrusions, or angled intrusions. The method of any one of claims 1 to 9, wherein said porous region has a porosity of at least about 30% to about 60% volume fraction, a mean pore size diameter ranging from about 20 to about 1000 microns, a coating thickness of from about 20 to about 2000 microns, or any combination thereof. The method of any one of claims 1 to 10, the secondary oxidation process is an electrolytic oxidation process. The method of claim 11, wherein said electrolytic oxidation process is a plasma electrolytic oxidation (PEO) process. The method of any one of claims 1 to 12, wherein the porosity of the beam-textured surface is increased by the secondary oxidation process. The method of any one of claims 1 to 12, wherein after the secondary oxidation process, said porous region has a porosity of at least about 30-80% volume fraction of porosity, a mean pore diameter ranging from about 600 to about 900 microns, a coating thickness ranging from about 1000 to about 2000 microns, or any combination thereof. The method of claim 14, wherein the secondary oxidation process forms a porous region having an oxide surface layer that ranges from 1000 to 2000 microns in thickness. The method of any one of claims 1 to 15 which comprises incorporating an additional substance into the porous region or as a surface coating. The method of claim 16, wherein said additional substance comprises calcium, phosphorous or both. The method of claim 17, wherein said substance is hydroxyapatite and enhances the bioactivity of the porous region. The method of any one of claims 16-18, wherein the secondary oxidation process is an electrolytic oxidation process which comprises an electrolyte solution comprising calcium- and phosphorous-containing compounds. The method of any one of claims 1 to 16, which wherein one or more surface areas of the zirconium-containing component are masked during the secondary oxidation process to preserve the characteristics of the ceramic oxide layer. A method of forming one or more porous regions on ceramic oxide surfaces of zirconium-containing components of medical devices which comprises masking one or more regions of said medical device and treating said device by an oxidation process to selectively create one or more porous regions in one more ceramic oxide surfaces of a zirconium-containing component of the medical device The method of claim 21, wherein the oxidation process is an electrolytic oxidation process. The method of claim 22, wherein said electrolytic oxidation process is a plasma electrolytic oxidation (PEO) process. The method of any one of claims 21 to 23, wherein the one or more porous regions have a porosity of at least about 30-80% volume fraction of porosity, a mean pore diameter ranging from about 20 to about 1000 microns, and preferably from about 600 to about 900 microns, a coating thickness ranging from about 20 to about 2000 microns, or any combination thereof. The method of claim 24, wherein the oxidation process forms one or more porous regions having an oxide surface layer that ranges from 1000 to 2000 microns in thickness. The method of any one of claims 21 to 25 which comprises incorporating an additional substance into the one or more porous regions. The method of claim 26, wherein said additional substance comprises calcium, phosphorous or both. The method of claim 27, wherein said substance is hydroxyapatite and enhances the bioactivity of the one or more porous regions.

- 26 - The method of any one of claims 26-28, wherein the oxidation process is an electrolytic oxidation process which comprises an electrolyte solution comprising calcium- and phosphorous-containing compounds. An implantable device formed by a method of any one of claims 1-29 to produce one or more porous regions in one or more ceramic oxide surfaces of a zirconium-containing component surface of said implantable device. The implantable medical device of claim 30, wherein said implantable device is selected from the group consisting of femoral implants, knee implants, hip implants, shoulder implants, ankle implants, spinal implants, trauma implants, mid-shaft implants, arthrodesis implants, UniSpacers, and cartilage replacements.

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