Patent Description:
Joint arthroplasty is a well-known surgical procedure by which a diseased and/or damaged natural joint is replaced by a prosthetic joint. A typical knee prosthesis includes a patella prosthetic component, a tibial tray, a femoral component, and a tibial bearing positioned between the tibial tray and the femoral component. Femoral components are designed to be attached to a surgically-prepared distal end of a patient's femur. Tibial trays are designed to be attached to a surgically-prepared proximal end of a patient's tibia.

The femoral component and the tibial tray can be made of biocompatible materials such as metal alloys of cobalt-chrome. The tibial bearing component disposed between the femoral component and the tibial tray can be formed from a plastic material like polyethylene. However, cobalt alloys tend to be expensive, and accordingly, a need exists for a component made from a non-cobalt metal material and a method of manufacturing the same. For example, a need exists for a femoral component of a knee prosthesis out of a non-cobalt metal material and a method for manufacturing the same. <CIT> provides an implant according to the preamble of claim <NUM>, with <CIT>, <CIT> and <CIT> representing other art in the area of coated implants.

According to an aspect of the disclosure, an orthopaedic implant includes a femoral component. The femoral component is configured to be coupled to the distal end of a patient's femur. The femoral component includes a substrate that comprises a titanium alloy. The substrate has a condylar surface that is curved in a sagittal plane and a bone-facing surface positioned opposite the condylar surface. An articular layer (also referred to as a "coating") is disposed on the condylar surface. The coating comprises a first layer (also referred to as a "bonding layer" or "inner layer") comprising niobium, zirconium, titanium, tantalum, platinum, molybdenum, or combinations thereof. The coating also comprises a second layer (also referred to as an "intermediate layer") comprising a number of alternating sublayers. The coating further comprises a third layer (also referred to as an "outer layer") comprising zirconium oxide, niobium oxide, zirconium oxynitride, niobium oxynitride, titanium, or a combination thereof. The first layer extends between and interconnects the second layer and the condylar surface. The second layer extends between and interconnects the first layer and the third layer. The third layer forms an outer articular surface of the femoral component.

In some embodiments, the second layer may comprise at least eight sublayers of alternating zirconium nitride and niobium nitride sublayers. In some embodiments, each zirconium nitride sublayer of the alternating sublayers may have a thickness of about <NUM> to about <NUM>. In some embodiments, the second layer may have a thickness of about <NUM> to about <NUM>.

In some embodiments, the third layer may comprise at least about <NUM>% monoclinic oxidized zirconium. In some embodiments, the third layer may have a thickness of about <NUM> to about <NUM>.

In some embodiments, at least one sublayer of the second layer may comprise at least about <NUM>% zirconium nitride.

In some embodiments, at least one sublayer of the second layer may have a thickness of about <NUM> to about <NUM>. In some embodiments, at least one sublayer of the second layer may comprise at least about <NUM>% niobium nitride.

In some embodiments, the first layer may comprise at least about <NUM>% zirconium. In some embodiments, the first layer may have a thickness of about <NUM> to about <NUM>.

Illustratively, the femoral component may include a bone-engaging layer disposed on the bone-facing surface. In some embodiments, the bone-engaging layer may be porous.

In some embodiments, the second layer may comprise an inner sublayer and an outer sublayer. In some embodiments, the inner sublayer and the outer sublayer may have the same composition. In some embodiments, the second layer may comprise an intermediate sublayer having a composition different from the inner sublayer, the outer sublayer, or both.

In some embodiments, the third layer may be titanium zirconium nitride. Additionally, in some embodiments, the atomic percent of zirconium in the third layer may be <NUM> At% to <NUM> At%. In some embodiments, the atomic percent of zirconium in the third layer may be <NUM> At% to <NUM> At%.

In some embodiments, the number of alternating sublayers include a number of titanium zirconium nitride sublayers and a number of metallic layers. In some embodiments, the atomic percent of zirconium in the plurality of alternating sublayers is <NUM> At% to <NUM> At%. Additionally, in some embodiments, the atomic percent of zirconium-titanium alloy in the plurality of alternating sublayers is <NUM> At% to <NUM> At%.

According to another aspect, a process for forming a femoral component of an orthopaedic knee implant includes depositing a first layer comprising niobium, zirconium, titanium, tantalum, platinum, molybdenum, or combinations thereof, on a condylar surface of a substrate. The substrate comprises titanium. The condylar surface is curved in a sagittal plane. In some embodiments, the process includes depositing a second layer that comprises a number of alternating sublayers.

The process may include oxidizing a portion of the second layer to form a third layer comprising oxidized zirconium.

The alternating sublayers may comprise a sublayer of zirconium nitride and a sublayer of niobium. Depositing the number of alternating sublayers to form the second layer may comprise (a) creating a sublayer of zirconium nitride on the first layer, (b) creating a sublayer of niobium on the sublayer of zirconium nitride, and (c) repeating steps (a) and (b) to form the second layer.

The process may include depositing a third layer on an outer surface of the second layer. The third layer may comprise zirconium oxide, niobium oxide, zirconium oxynitride, niobium oxynitride, or a combination thereof.

The detailed description particularly refers to the following figures, in which:.

While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications and alternatives falling within the scope of the invention as defined by the appended claims.

Terms representing anatomical references, such as anterior, posterior, medial, lateral, superior, inferior, etcetera, may be used throughout the specification in reference to the orthopaedic implants or orthopaedic prostheses described herein as well as in reference to the patient's natural anatomy. Such terms have well-understood meanings in both the study of anatomy and the field of orthopaedics. Use of such anatomical reference terms in the written description and claims is intended to be consistent with their well-understood meanings unless noted otherwise.

Referring now to <FIG>, in one example, an orthopaedic knee prosthesis <NUM> includes a femoral component <NUM>, a tibial bearing <NUM>, and a tibial tray <NUM>. The femoral component <NUM> is configured to articulate with the tibial bearing <NUM>, which is configured to be coupled with the tibial tray <NUM>. In the illustrative embodiment of <FIG>, the tibial bearing <NUM> is embodied as a rotating or mobile tibial bearing and is configured to rotate relative to the tibial tray <NUM> during use. However, in other examples, the tibial bearing <NUM> may be embodied as a fixed tibial bearing, which may be limited or restricted from rotating relative to the tibial tray <NUM>.

The tibial tray <NUM> is configured to be secured to a surgically-prepared proximal end of a patient's tibia (not shown). The tibial tray <NUM> may be secured to the patient's tibia via use of bone cement or other attachment methods. The tibial tray <NUM> includes a platform <NUM> having a top surface <NUM> and a bottom surface <NUM>. Illustratively, the top surface <NUM> is generally planar. The tibial tray <NUM> also includes a stem <NUM> extending downwardly from the bottom surface <NUM> of the platform <NUM>. A cavity or bore <NUM> is defined in the top surface <NUM> of the platform <NUM> and extends downwardly into the stem <NUM>. The bore <NUM> is formed to receive a complimentary stem <NUM> of the tibial bearing <NUM> as discussed in more detail below.

As discussed above, the tibial bearing <NUM> is configured to be coupled with the tibial tray <NUM>. The tibial bearing <NUM> includes a platform <NUM> having an upper bearing surface <NUM> and a bottom bearing surface <NUM>. In the illustrative example wherein the tibial bearing <NUM> is embodied as a rotating or mobile tibial bearing, the bearing <NUM> includes a stem <NUM> extending downwardly from the bottom surface <NUM> of the platform <NUM>. When the tibial bearing <NUM> is coupled to the tibial tray <NUM>, the stem <NUM> is received in the bore <NUM> of the tibial tray <NUM>. In use, the tibial bearing <NUM> is configured to rotate about an axis defined by the stem <NUM> relative to the tibial tray <NUM>. In examples wherein the tibial bearing <NUM> is embodied as a fixed tibial bearing, the bearing <NUM> may or may not include the stem <NUM> and/or may include other devices or features to secure the tibial bearing <NUM> to the tibial tray <NUM> in a non-rotating configuration.

The upper bearing surface <NUM> of the tibial bearing <NUM> includes a medial bearing surface <NUM> and a lateral bearing surface <NUM>. The medial and lateral bearing surfaces <NUM>, <NUM> are configured to receive or otherwise contact corresponding medial and lateral condyles <NUM>, <NUM> of the femoral component <NUM> as discussed in more detail below. As such, each of the bearing surfaces <NUM>, <NUM> has a concave contour.

The femoral component <NUM> is configured to be coupled to a surgically-prepared surface of the distal end of a patient's femur (not shown). The femoral component <NUM> may be secured to the patient's femur via use of bone adhesive or other attachment methods. The femoral component <NUM> includes a pair of medial and lateral condyles <NUM>, <NUM>. The condyles <NUM>, <NUM> are spaced apart to define an intracondyle notch <NUM> therebetween. In use, the condyles <NUM>, <NUM> replace the natural condyles of the patient's femur and are configured to articulate on the corresponding bearing surfaces <NUM>, <NUM> of the platform <NUM> of the tibial bearing <NUM>.

The illustrative orthopaedic knee prosthesis <NUM> (sometime referred to as an "implant") of <FIG> is embodied as a posterior cruciate-retaining knee prosthesis. That is, the femoral component <NUM> is embodied as a posterior cruciate-retaining knee prosthesis and the tibial bearing <NUM> is embodied as a posterior cruciate-retaining tibial bearing <NUM>. However, in other examples, the orthopaedic knee prosthesis <NUM> may be embodied as a posterior cruciate-sacrificing knee prosthesis.

Referring now to <FIG> and <FIG>, the femoral component <NUM> is configured to articulate on the tibial bearing <NUM> during use. Each condyle <NUM>, <NUM> of the femoral component <NUM> includes an outer articular surface <NUM>, which is convexly curved in the sagittal plane and configured to face the respective bearing surface <NUM>, <NUM> of the tibial bearing <NUM>.

As shown in <FIG>, the femoral component <NUM> includes a substrate <NUM> and a coating <NUM>. Illustratively, the coating <NUM> is disposed on the substrate <NUM> and is configured to interact with the tibial bearing <NUM>. The femoral component <NUM> includes a bone-engaging layer <NUM> located opposite the coating <NUM> to locate the substrate <NUM> therebetween. The bone-engaging layer <NUM> is configured to interact with a surgically prepared femur of a patient.

The substrate <NUM> comprises a condylar surface <NUM> and a bone-facing surface <NUM>, as shown in <FIG>. The condylar surface <NUM> is curved in a sagittal plane and is configured to locate the coating <NUM> on the substrate <NUM>. The bone-facing surface <NUM> is positioned opposite the condylar surface <NUM> and is arranged to face a surgically-prepared distal end of a patient's femur. The bone-facing surface <NUM> contacts the surgically-prepared femur bone directly. In some embodiments, a bone-engaging layer <NUM> is coupled to the bone-facing surface <NUM> of the substrate <NUM>.

<FIG> and <FIG> show a cementless example of the femoral component <NUM> where the bone-engaging layer <NUM> is configured to be implanted in the absence of cement between the femoral component <NUM> and the surgically-prepared distal end of a patient's femur. The bone-engaging layer <NUM> comprises titanium. It should be appreciated that the bone-engaging layer <NUM> could be a separately-applied coating such as Porocoat® Porous Coating, which is commercially available from DePuy Synthes of Warsaw, Indiana.

In some examples, the bone-engaging layer <NUM> can be defined by a porous three-dimensional structure formed by a plurality of interconnected struts. In one example, the plurality of interconnected struts form a plurality of geometric structures, which, in the illustrative example, are rhombic trigonal trapezohedrons. It should be appreciated that such geometric structures may vary to fit the needs of a given design. Further, it should be appreciated that the bone-engaging layer <NUM> may be formed from any other alternative geometry suitable to fit the needs of a given design.

In some examples, the bone-engaging layer <NUM> is formed from a metal powder. Illustratively, the metal powder may include, but are not limited to, titanium, titanium alloys, stainless steel, cobalt chrome alloys, tantalum, niobium, or a combination thereof. The bone-engaging layer <NUM> has a porosity suitable to facilitate bony ingrowth into the bone-engaging layer <NUM> of the femoral component <NUM> when implanted into the surgically-prepared surface of the distal end of a patient's femur.

In the illustrative example described herein, the bone-engaging layer <NUM> is additively manufactured directly onto the bone-facing surface <NUM> of the femoral component <NUM>. The two structures - i.e., the femoral component <NUM> and bone-engaging layer <NUM> - may be manufactured contemporaneously during a common additive manufacturing process. For example, the two structures may be manufactured contemporaneously in a single 3D printing operation that yields a common, monolithic metallic component including both structures. Alternatively, the bone-engaging layer <NUM> could be manufactured as a separate component that is secured to the bone-facing surface <NUM> of the femoral component <NUM>.

In alternative examples, the femoral component <NUM> is configured to attach to the surgically-prepared distal end of a patient's femur using cement. In some examples, the femoral component <NUM> comprises a cement reservoir (not shown) disposed on the bone-facing surface <NUM>. In some examples, the bone adhesive is disposed on the bone-facing surface <NUM>. In some examples, the bone adhesive comprises bone cement. In some examples, the bone-facing surface <NUM> is configured to receive a bone adhesive.

In some examples, the substrate <NUM> is metallic. In some examples, the substrate <NUM> comprises a metal alloy. According to the invention, the substrate <NUM> comprises a titanium alloy. In some embodiments, the substrate <NUM> comprises titanium and vanadium. In some embodiments, the substrate <NUM> comprises titanium, aluminum, and vanadium. In some embodiments, the substrate <NUM> comprises Ti-6Al-4V. In some embodiments, the substrate <NUM> consists essentially of Ti-6Al-4V.

Referring now to <FIG> and <FIG>, the coating <NUM> is disposed on the condylar surface <NUM>. The coating <NUM> is located opposite the bone-facing surface <NUM> to locate the substrate <NUM> therebetween. The coating <NUM> is configured to interact with the bearing surfaces <NUM>, <NUM> and to articulate with the tibial bearing <NUM>.

The coating <NUM> has a number of layers <NUM>, <NUM>, <NUM>. The layers <NUM>, <NUM>, <NUM> may each be constructed with a material which possesses mechanical properties favorable for use in the construction of the coating <NUM> (e.g., enhanced wear resistance, resists chipping, resists delamination, tunable stiffness, ductile, corrosion resistance, and oxidation resistance).

In some embodiments, the coating <NUM> cooperates with the substrate <NUM> to minimize scratching of the outer articular surface <NUM> of the femoral component <NUM>. In some embodiments, the coating <NUM> cooperates with the substrate <NUM> to minimize cohesive chipping and delamination of the coating <NUM>. In some embodiments, the coating <NUM> cooperates with the substrate <NUM> to resist corrosion. In some embodiments, the coating <NUM> provides density and toughness. In some embodiments, the coating <NUM> cooperates with the substrate <NUM> to provide sufficient toughness to minimize or avoid fracturing.

Referring now to <FIG>, the coating <NUM> comprises an inner or bonding layer <NUM>, an intermediate layer <NUM>, and an outer layer <NUM>. The outer layer <NUM>, the intermediate layer <NUM>, or both the outer layer <NUM> and the intermediate layer <NUM> of the coating <NUM> is constructed with a material which possesses mechanical properties favorable for use in the construction of the coating <NUM>. For example, the intermediate layer <NUM> is constructed with materials that provide a stiffness and ductility that spread the load of a force, arrest cracking, and improve adhesion of the coating <NUM> to the substrate <NUM>. The bonding layer <NUM>, on the other hand, is constructed of a material which possesses mechanical properties favorable for use in securing the coating <NUM> to the substrate <NUM>.

It should be appreciated that, as used herein, the term "layer" is not intended to be limited to a "thickness" of material positioned proximate to another similarly dimensioned "thickness" of material, but rather is intended to include numerous structures, configurations, and constructions of material. For example, the term "layer" may include a portion, region, or other structure of material which is positioned proximate to another portion, region, or structure of differing material. For example, although the interface between the intermediate layer <NUM> and the outer layer <NUM> is shown to be uniform in <FIG>, in some embodiments the interface is irregular such that the intermediate layer <NUM> and the outer layer <NUM> do not have a uniform thickness. In some embodiments, a "layer" is formed by modifying a surface or a portion of an existing layer. For example, in some embodiments, the outer layer <NUM> is formed from oxidizing an outer portion of the intermediate layer <NUM>. In alternative embodiments, a "layer" is formed by providing additional material to an existing surface. For example, in some embodiments, the bonding layer <NUM> is formed by depositing a material onto the condylar surface <NUM>.

As shown in <FIG>, the bonding layer <NUM> is disposed on the condylar surface <NUM>. The outer layer <NUM> is arranged to form the outer articular surface <NUM> of the coating <NUM> and hence the femoral component <NUM>. The intermediate layer <NUM> extends between and interconnects the bonding layer <NUM> and the outer layer <NUM>. In some illustrative examples which do not form part of the present invention, the coating <NUM> does not include an outer layer <NUM> (as shown in <FIG>) such that an exposed surface of the intermediate layer <NUM> may be further processed to form the outer articular surface <NUM>.

The bonding layer <NUM> extends between and interconnects the intermediate layer <NUM> and the condylar surface <NUM>. The inner layer <NUM> includes an inner surface <NUM> and an outer surface <NUM>. The inner surface <NUM> is located between the outer surface <NUM> and the condylar surface <NUM>. The outer surface <NUM> of the inner layer <NUM> is located between the inner surface <NUM> of the inner layer <NUM> and the intermediate layer <NUM>. In some embodiments, the inner layer <NUM> is configured to reduce delamination of the coating <NUM> from the femoral component <NUM>.

The bonding layer <NUM> may have a particular thickness as measured from the condylar surface <NUM>. In some embodiments, the bonding layer <NUM> may be present at a thickness in the nanoscale to the micron scale. In some embodiments, the bonding layer <NUM> has a thickness of about <NUM> to about <NUM>, about <NUM> to about <NUM>, or about <NUM> to about <NUM>. In some embodiments, the bonding layer <NUM> has a thickness of about <NUM> to about <NUM>. In some embodiments, the bonding layer <NUM> has a thickness of about <NUM> to about <NUM>. In some embodiments, the bonding layer <NUM> has a thickness of at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM>. In some embodiments, the bonding layer <NUM> has a thickness of about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about, or about <NUM>.

The bonding layer <NUM> may include metals, alloys, or other suitable material to provide mechanical properties favorable for use in securing the coating <NUM> to the substrate <NUM>. For example, the composition of the bonding layer <NUM> can be selected to minimize cohesive chipping of the coating <NUM> during manufacturing and in use. According to the invention, the bonding layer <NUM> comprises niobium, zirconium, titanium, tantalum, molybdenum, platinum, hafnium, or combinations thereof. In some embodiments, the bonding layer <NUM> comprises zirconium. In some embodiments, the bonding layer <NUM> comprises at least about <NUM>% zirconium. In some embodiments, the bonding layer <NUM> comprises at least about <NUM>% zirconium. In some embodiments, the bonding layer <NUM> comprises at least about <NUM>% of niobium, titanium, tantalum, molybdenum, platinum, or combinations thereof. In some embodiments, the bonding layer <NUM> comprises at least about <NUM>% niobium, zirconium, titanium, tantalum, molybdenum, platinum, hafnium, or combinations thereof.

As described above, the intermediate layer <NUM> extends between and interconnects the bonding layer <NUM> and the outer layer <NUM>. The intermediate layer <NUM> comprises an inner surface <NUM> and outer surface <NUM>. The inner surface <NUM> of the intermediate layer <NUM> is located between the inner layer <NUM> and the outer surface <NUM> of the intermediate layer <NUM>. The outer surface <NUM> of the intermediate layer <NUM> is located between the inner surface <NUM> of the intermediate layer <NUM> and the outer layer <NUM>.

In some embodiments, the intermediate layer <NUM> has an overall thickness of about <NUM> to about <NUM>. In some embodiments, the intermediate layer <NUM> has an overall thickness of about <NUM> to about <NUM>. In some embodiments, the intermediate layer <NUM> has an overall thickness of about <NUM> to about <NUM>. In some embodiments, the intermediate layer <NUM> has an overall thickness of about <NUM> to about <NUM>. In some embodiments, the intermediate layer <NUM> has an overall thickness of at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM>. In some embodiments, the intermediate layer <NUM> has an overall thickness of about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>.

The intermediate layer <NUM> is formed of a plurality of sublayers. The order and composition of the sublayers <NUM>, <NUM>, <NUM> are configured to disperse the load and arrest cracking that may occur. In an illustrative embodiment, the intermediate layer <NUM> is formed of an inner sublayer <NUM>, an intermediate sublayer <NUM>, and an outer sublayer <NUM>. Some or all of the sublayers <NUM>, <NUM>, <NUM> repeat so that the intermediate layer <NUM> includes two or more of one of the sublayers.

The sublayers <NUM>, <NUM>, <NUM> can include metals, alloys, ceramics, or other suitable materials as described herein. Illustratively, the various combinations of sublayers <NUM>, <NUM>, or <NUM> provide fracture toughness and corrosion resistance. For example, each of the sublayers <NUM>, <NUM>, and <NUM> may comprise niobium, zirconium, titanium, tantalum, hafnium, molybdenum, platinum, combinations thereof, or any other suitable metal, including alloys thereof. Each of the sublayers <NUM>, <NUM>, and <NUM> may comprise a ceramic comprising niobium, zirconium, titanium, tantalum, molybdenum, platinum, combinations thereof, or any other suitable ceramic. Illustratively, a ceramic may comprise a metal and a nitride, a carbide, an oxide, or combinations thereof. For example, the ceramic may comprise zirconium nitride, titanium zirconium nitride, zirconium oxide, or niobium nitride.

In some embodiments, the number of alternating sublayers include a number of titanium zirconium nitride sublayers and a number of metallic layers. In some embodiments, the atomic percent of zirconium in the plurality of alternating sublayers is <NUM> At% to <NUM> At%. In some embodiments, the atomic percent of zirconium in the plurality of alternating sublayers is about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, or about <NUM> At%. Additionally, in some embodiments, the atomic percent of zirconium-titanium alloy in the plurality of alternating sublayers is <NUM> At% to <NUM> At%. In some embodiments, the atomic percent of zirconium-titanium alloy in the plurality of alternating sublayers is about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, or about <NUM> At%.

In illustrative embodiments, some of or all of the sublayers <NUM>, <NUM>, <NUM> may participate in a super lattice with adjacent layers or sublayers. In some embodiments, each of the sublayers <NUM>, <NUM>, <NUM> has a thickness of about <NUM> to about <NUM>, about <NUM> to about <NUM>, or about <NUM> to about <NUM>. In some embodiments, each of the sublayers <NUM>, <NUM>, <NUM> has a thickness of about <NUM> to about <NUM>.

The intermediate layer <NUM> may comprise two different sublayers, which may be superimposed alternatingly. Referring to <FIG> for example, the intermediate layer <NUM> may comprise an inner sublayer <NUM>, an intermediate sublayer <NUM>, and an outer sublayer <NUM>. The compositions of the inner sublayer <NUM>, the intermediate sublayer <NUM>, and the outer sublayer <NUM> may be the same or different. For example, the intermediate layer <NUM> may comprise a sequence of two sublayers, for example the inner sublayer <NUM> and the intermediate sublayer <NUM>, having the composition -A-B- or (-A-B-)n where each of A and B are a different composition and n is at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM>. In this embodiment, inner sublayer <NUM> is A and intermediate sublayer <NUM> is B. Where there is a repeat of two sublayers, such as A-B-A-B-A-B for example, each A-B may be referred to as a "bilayer. " Accordingly, a bilayer is a grouping of two sublayers. In some embodiments, the composition of layer A comprises zirconium nitride. In some embodiments, the composition of layer B comprises niobium nitride, tantalum nitride, hafnium nitride, niobium, tetragonal and/or monoclinic zirconium, tantalum, titanium, or hafnium. In some embodiments, the number of alternating sublayers is chosen so that the intermediate layer <NUM> reaches an overall thickness of, for example, up to about <NUM>, up to about <NUM>, up to about <NUM>, or up to about <NUM>.

Alternatively, the intermediate layer <NUM> may have a sequence of two repeating sublayers, for example an inner sublayer <NUM> and an intermediate sublayer <NUM>, and an outer sublayer <NUM>, as shown in <FIG> and <FIG>. In some examples, the intermediate layer <NUM> includes a sequence A-(B-A)n-C- including a repeating inner sublayer <NUM> and intermediate sublayer <NUM> where each of A and B are a different composition and n is at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM>, and where C is the outer sublayer <NUM> and has the same composition as one of the inner sublayer <NUM> or the intermediate sublayer <NUM>. In some embodiments, the composition of layer A comprises zirconium nitride. In some embodiments, the composition of layer B comprises niobium nitride, tantalum nitride, hafnium nitride, niobium, tetragonal and/or monoclinic zirconium, tantalum, titanium, or hafnium. In some embodiments, the outer sublayer <NUM> comprises zirconium nitride. In some embodiments, the intermediate layer <NUM> comprises a repeating sequence of i) a sublayer of zirconium nitride, ii) a sublayer of niobium, tetragonal and/or monoclinic zirconium, tantalum, titanium hafnium, niobium nitride, tantalum nitride, or hafnium nitride, and iii) capped by an outer sublayer <NUM> of zirconium nitride. In some embodiments, the number of alternating sublayers is chosen so that the intermediate layer <NUM> reaches a thickness of, for example, up to about <NUM>.

Alternatively, the intermediate layer <NUM> may have a sequence of three repeating sublayers, for example, an inner sublayer <NUM>, an intermediate sublayer <NUM>, and an outer sublayer <NUM>. In some examples, the intermediate layer <NUM> includes a repeating sequence of the inner sublayer <NUM>, the intermediate sublayer <NUM>, and the outer sublayer <NUM>, having the composition -(A-B-C)n- where each of A, B, and C are a different composition and n is at least <NUM>, at least <NUM>, or at least <NUM>. In this embodiment, inner sublayer <NUM> is A, intermediate sublayer <NUM> is B, and outer sublayer <NUM> is C. Where there is a repeat of three sublayers, such as A-B-C-A-B-C-A-B-C for example, each A-B-C may be referred to as a "trilayer. " Accordingly, a trilayer is a grouping of three sublayers. It should be noted that although the formula shows a sequence of A-B-C, any permutation on the order of the sublayers is contemplated, for example A-C-B, B-C-A, etc. It should be further noted that the intermediate layer <NUM> may comprise more than one sequence of sublayers, for example a sequence of -A-B-C-B-C-A- and the like. It should be further noted that the intermediate layer <NUM> may comprise more than one sequence of sublayers, for example a sequence of -A-B-A-B-A-B-A-C-A-C-A-C- and the like. It should be further noted that the intermediate layer <NUM> may comprise more than one sequence of sublayers, for example a sequence of -A-B-A-C-A-B-A-C-A-B-A-C- and the like. Referring to <FIG> for example, the intermediate layer <NUM> may comprise a first sequence of two sublayers having the composition -A-B- or (-A-B-)n where each of A and B are a different composition and n is at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM> and a second sequence of two sublayers having the composition -A-C- or (-A-C-)n where each of A and C are a different composition and n is at least <NUM>, at least <NUM>, at least <NUM>, or at least <NUM>. Illustratively, any of composition A, B, or C can include niobium nitride, tantalum nitride, hafnium nitride, zirconium nitride, niobium, tetragonal and/or monoclinic zirconium, tantalum, titanium, or hafnium.

In some embodiments, the intermediate layer <NUM> comprises a zirconium nitride inner sublayer <NUM>, a niobium nitride intermediate sublayer <NUM>, and a zirconium nitride outer sublayer <NUM>. In some embodiments, the intermediate layer <NUM> comprises at least one zirconium nitride inner sublayer <NUM> and at least one niobium nitride intermediate sublayer <NUM>. In some embodiments, the intermediate layer <NUM> comprises a number of alternating sublayers of zirconium nitride and niobium nitride. In some embodiments, the intermediate layer <NUM> comprises at least four alternating sublayers of the zirconium nitride inner sublayer <NUM> and the niobium nitride intermediate sublayer <NUM>. In illustrative embodiments, the zirconium nitride outer sublayer <NUM> is formed on the outermost niobium nitride intermediate sublayer <NUM>. It will be appreciated that although <FIG> shows a single sublayer of the zirconium nitride inner sublayer <NUM> and a single sublayer of the niobium nitride intermediate sublayer <NUM>, any number of alternating sublayers is contemplated.

In some embodiments, the inner sublayer <NUM> has a thickness of about <NUM> to about <NUM>. In some embodiments, the inner sublayer <NUM> has a thickness of at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM>. In some embodiments, the inner sublayer <NUM> has a thickness of about <NUM> to about <NUM> or about <NUM> to about <NUM>. In some embodiments, the sublayer <NUM> has a thickness of about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>. In some embodiments, the sublayer <NUM> has a thickness of about <NUM>, about <NUM>, about <NUM>, about <NUM> or about <NUM>.

In some embodiments, the inner sublayer <NUM> comprises at least about <NUM>% zirconium nitride. In some embodiments, the inner sublayer <NUM> comprises at least about <NUM>% zirconium nitride.

In some embodiments, the intermediate sublayer <NUM> has a thickness of about <NUM> to about <NUM>. In some embodiments, the intermediate sublayer <NUM> has a thickness of at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM>. In some embodiments, the sublayer <NUM> has a thickness of about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>. In some embodiments, the sublayer <NUM> has a thickness of about <NUM>, about <NUM>, about <NUM>, about <NUM> or about <NUM>.

In some embodiments, the intermediate sublayer <NUM> comprises at least about <NUM>% niobium nitride, tantalum nitride, hafnium nitride, niobium, tetragonal and/or monoclinic zirconium, tantalum, titanium, or hafnium. In some embodiments, the intermediate sublayer <NUM> comprises at least about <NUM>% niobium nitride, tantalum nitride, hafnium nitride, niobium, tetragonal and/or monoclinic zirconium, tantalum, titanium, or hafnium.

In some embodiments, the outer sublayer <NUM> has a thickness of about <NUM> to about <NUM>. In some embodiments, the outer sublayer <NUM> has a thickness of about <NUM> to about <NUM>. In some embodiments, the outer sublayer <NUM> has a thickness of at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM>. In some embodiments, the outer sublayer <NUM> forms the outer articular surface <NUM> of the femoral component <NUM> and coating <NUM>.

In some embodiments, the outer sublayer <NUM> comprises at least about <NUM>% zirconium nitride. In some embodiments, the outer sublayer <NUM> comprises at least about <NUM>% zirconium nitride.

The outer layer <NUM> is configured to form the outer articular surface <NUM> of the coating <NUM> and hence the femoral component <NUM>. The outer layer <NUM> comprises an inner surface <NUM> and an outer surface <NUM>. The inner surface <NUM> of the outer layer <NUM> is located between the intermediate layer <NUM> and the outer surface <NUM> of the outer layer <NUM>. The outer surface <NUM> of the outer layer <NUM> forms an outer surface <NUM> of the femoral component <NUM>. Illustratively, the outer surface <NUM> of the outer layer <NUM> forms the outer articular surface <NUM> of the femoral component <NUM> and is configured to interact and rotate about the tibial bearing <NUM>, as shown in <FIG>.

In some examples, the outer layer <NUM> can be formed by depositing the outer layer <NUM> or by thermal growth through oxidation of a portion of the intermediate layer <NUM>. In some embodiments, the outer layer <NUM> has a thickness of at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM>. In some embodiments, the outer layer <NUM> has a thickness of at least about <NUM>, at least about <NUM>, at least about <NUM>, at least about <NUM>, or at least about <NUM>. When the outer layer <NUM> is deposited, the outer layer <NUM> can have a thickness of about <NUM> to about <NUM>. When the outer layer <NUM> is formed by oxidation, the outer layer <NUM> can have a thickness of about <NUM> to about <NUM>. In some embodiments, the outer layer <NUM> has a thickness of about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM>.

In an illustrative embodiment, the outer layer <NUM> is formed by oxidizing at least part of the intermediate layer <NUM>. For example, the outer surface <NUM> of the intermediate layer <NUM> can be oxidized to thermally grow the outer layer <NUM>. Illustratively, the thermal growing may occur by oxygen inserting into the lattice of portions, for example an outer portion, of the intermediate layer <NUM> to form an oxide. In some embodiments, the outer layer <NUM> comprises a ceramic. In illustrative embodiments, the ceramic of the outer layer <NUM> is an oxide of the composition of the intermediate layer <NUM>. In some embodiments, the outer layer <NUM> comprises an oxide of a niobium and zirconium alloy. In some embodiments, the outer layer <NUM> comprises zirconium oxide. In some embodiments, the outer layer <NUM> comprises niobium oxide. In some embodiments, the outer layer <NUM> comprises zirconium oxide and niobium oxide. In some embodiments, the outer layer <NUM> comprises monoclinic zirconium oxide. In some embodiments, the outer layer <NUM> comprises at least about <NUM>% zirconium oxide. In some embodiments, the outer layer <NUM> comprises at least about <NUM>% monoclinic zirconium oxide. In some embodiments, the outer layer <NUM> comprises monoclinic and/or tetragonal zirconium oxynitride. In some embodiments, the outer layer <NUM> comprises at least about <NUM>% zirconium oxynitride. In some embodiments, the outer layer <NUM> comprises at least about <NUM>% tetragonal zirconium oxide. In some embodiments, the outer layer <NUM> comprises at least about <NUM>% cubic zirconium oxide. In some embodiments, the outer layer <NUM> comprises a ceramic that includes titanium. In one illustrative aspect, the outer layer <NUM> comprises titanium zirconium nitride. In some embodiments, the outer layer <NUM> comprises an oxidized metal and titanium.

In illustrative embodiments, the outer layer <NUM> is formed by depositing the outer layer <NUM>. In some illustrative embodiments, the outer layer <NUM> comprises deposited zirconium oxide. The deposited zirconium oxide of the outer layer <NUM> can be tetragonal zirconium oxide or monoclinic zirconium oxide. In an illustrative embodiment, when monoclinic zirconium oxide is deposited, a layer of tetragonal zirconium oxide will form between the monoclinic zirconium oxide and the intermediate layer <NUM>. In some illustrative embodiments, the outer layer <NUM> is formed by increasing the concentration of oxygen while depositing the outermost sublayer of the intermediate layer <NUM> such that the outer layer <NUM> is an oxide of the outermost sublayer of the intermediate layer <NUM>. For example, if the outermost sublayer (e.g., outer sublayer <NUM>) of the intermediate layer <NUM> is zirconium nitride, the outer layer <NUM> can be formed by increasing the oxygen concentration of the deposition to form oxidized zirconium nitride, sometimes called zirconium oxynitride. In some embodiments, the outer layer <NUM> may comprise zirconium oxynitride and niobium oxynitride.

In some embodiments, the third layer may be titanium zirconium nitride. Additionally, in some embodiments, the atomic percent of zirconium in the third layer may be <NUM> At% to <NUM> At%. In some embodiments, the atomic percent of zirconium in the third layer may be about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, or about <NUM> At%. In some embodiments, the atomic percent of zirconium in the third layer may be <NUM> At% to <NUM> At%. In some embodiments, the atomic percent of zirconium in the third layer may be about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, about <NUM> At%, or about <NUM> At%.

In some embodiments, the bonding layer <NUM> comprises zirconium, the intermediate layer <NUM> comprises at least one zirconium nitride sublayer <NUM> and at least one niobium nitride sublayer <NUM>, and the outer layer <NUM> comprises oxidized zirconium.

Referring now to <FIG>, the femoral component <NUM> of an orthopaedic knee prosthesis <NUM> may be formed through a process <NUM>. In some embodiments, the process <NUM> comprises a first depositing step <NUM> of depositing the bonding layer <NUM>, a second depositing step <NUM> of depositing the intermediate layer <NUM>, and an oxidizing step <NUM>. In illustrative embodiments, the process <NUM> includes the steps of preparing the substrate <NUM> for the step of depositing <NUM>. In some embodiments, the process <NUM> includes finishing steps after the step of oxidizing <NUM> such as polishing.

Referring now to <FIG>, shown are illustrative diagrammatic embodiments of a femoral component <NUM>. Illustratively, A denotes a sublayer and is shown in optionally repeating stack with a sublayer of zirconium nitride as shown in <FIG>.

Referring now to <FIG>, shown are illustrative diagrammatic embodiments of a femoral component <NUM>. In each example, A denotes a portion of the substrate <NUM>, B denotes a layer or sublayer comprising niobium, C denotes a layer or sublayer comprising zirconium nitride, one B and one C together form a bilayer, and D denotes a layer comprising niobium nitride. In some embodiments, the outer layer <NUM> of C denotes a layer comprising Ti-doped zirconium nitride. As shown illustratively in <FIG>, the bonding layer <NUM> comprises niobium. Bonding layer <NUM> comprises niobium, zirconium, titanium, tantalum, platinum, molybdenum, alloys thereof, or combinations thereof.

As shown in the embodiment of <FIG>, the intermediate layer <NUM> includes a number of alternating sublayers (C and B) such that n = <NUM> and the outer layer <NUM> is a single layer C. In the illustrative example of <FIG>, the intermediate layer <NUM> is a single layer D. In this example, single layer D may be further processed to form the outer articular surface <NUM> (e.g., oxidized). In the embodiment of <FIG>, the intermediate layer <NUM> includes a number of alternating sublayers (C and B) and (C and D) such that n= <NUM> and the outer layer <NUM> is a single layer C. In the embodiment of <FIG>, the intermediate layer <NUM> includes a number of alternating sublayers (C and D) and (B and C) such that n = <NUM> and the outer layer <NUM> is a single layer C. In the embodiment of <FIG>, the intermediate layer <NUM> includes a number of alternating sublayers (C-D-C-B) such that n = <NUM> and the outer layer <NUM> is a single layer C. In the embodiment of <FIG>, the intermediate layer <NUM> includes a number of alternating sublayers (C and D) such that n = <NUM> and the outer layer <NUM> is a single layer C.

The intermediate layer <NUM> can include repeating stacks of layers. In some embodiments, the intermediate layer <NUM> comprises a repeating stack of a sublayer comprising zirconium nitride and a sublayer comprising niobium, as illustratively shown in <FIG>. In some embodiments, the intermediate layer <NUM> comprises a first repeating stack of a sublayer <NUM> comprising zirconium nitride and a sublayer <NUM> comprising niobium and a second repeating stack of a sublayer <NUM> comprising zirconium nitride and a sublayer <NUM> comprising niobium nitride, as illustratively shown in <FIG> and <FIG>. In some embodiments, the intermediate layer <NUM> comprises a repeating stack of a sublayer <NUM> comprising zirconium nitride, a sublayer <NUM> comprising niobium nitride, a sublayer <NUM> comprising zirconium nitride, and a sublayer <NUM> comprising niobium, as illustratively shown in <FIG>. In some embodiments, the intermediate layer <NUM> comprises a repeating stack of a sublayer <NUM> comprising zirconium nitride and a sublayer <NUM> comprising niobium nitride, as illustratively shown in <FIG>. In the embodiments of <FIG> and <FIG>, and in the illustrative example of <FIG>, the bonding layer <NUM> has a thickness of about <NUM> or about <NUM>. Each sublayer <NUM> and <NUM>, except for the sublayer <NUM> furthest the substrate, of the intermediate layer <NUM> has a thickness of about <NUM>. Illustratively, each of the embodiments/illustrative example in <FIG> includes an outer sublayer <NUM> of zirconium nitride having a thickness of about <NUM>. This outer layer can optionally undergo further processing to form the outer layer <NUM>.

Alternatively, the intermediate layer <NUM> may comprise repeating sublayer sequences, wherein repeats have a uniform thickness throughout the span of the intermediate layer <NUM> but the individual sublayers' thicknesses vary. Referring to <FIG>, sublayers <NUM> and <NUM> are stacked in a repeating sequence with each repeat having a combined thickness that is uniform in the intermediate layer <NUM>, but each individual thickness of sublayer <NUM> or sublayer <NUM> is varied. For example, the percentage thickness of sublayer <NUM> may decrease incrementally and the percentage thickness of sublayer <NUM> may increase incrementally for each subsequent sequence. In one embodiment, a sublayer <NUM> may be <NUM>% of the combined thickness and sublayer <NUM> may be <NUM>% of the combined thickness of the first sequence. Then in the second sequence, sublayer <NUM> may comprise <NUM>% and sublayer <NUM> may comprise <NUM>%. Following that, the third sequence may comprise <NUM>% sublayer <NUM> and <NUM>% sublayer <NUM>. In this manner, sublayer <NUM> and sublayer <NUM> are graded stepwise over the span of the intermediate layer <NUM>. In some embodiments, sublayer <NUM>'s presence in a sequence is reduced by <NUM>% in each subsequent sequences and sublayer <NUM>'s presence in a sequence is increased by <NUM>% over the span of intermediate layer <NUM>. Accordingly, each sequence of sublayer <NUM> and sublayer <NUM> maintains a uniform thickness throughout the span of intermediate layer <NUM>. Further exemplary embodiments are provided in Tables <NUM>, <NUM>, and <NUM>. In some embodiments, the amount present of sublayer <NUM> in a sequence reduces by about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>% about <NUM>%, about <NUM>%, about <NUM>% about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, or about <NUM>% in each subsequent sequence. Reciprocally, in some embodiments, the amount present of sublayer <NUM> increases about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>% about <NUM>%, about <NUM>%, about <NUM>% about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, about <NUM>%, or about <NUM>% in each subsequent sequence.

In some examples, , the first depositing step <NUM> deposits a material and forms the bonding layer <NUM> on the condylar surface <NUM> of the substrate <NUM>. In some examples, the first depositing step <NUM> is performed by physical vapor deposition (PVD). In some examples, the first depositing step <NUM> is performed by a magnetron sputter system. In other examples, PVD may be performed using HiPIMS, IBAD, or other deposition systems.

In some examples, the second depositing step <NUM> forms the intermediate layer <NUM> on the outer surface <NUM> of the bonding layer <NUM>. In some examples, the second depositing step <NUM> is performed by PVD. In some examples, the step of depositing <NUM> is performed by a magnetron sputter system.

In some examples, the second depositing step <NUM> comprises depositing the inner sublayer <NUM>. Illustratively, the inner sublayer <NUM> is deposited onto the bonding layer <NUM> by the second depositing step <NUM>.

In some examples, the second depositing step <NUM> comprises depositing the intermediate sublayer <NUM> onto the inner sublayer <NUM>. In illustrative examples, the second step of depositing <NUM> includes repeating the steps of depositing the inner sublayer <NUM> and the intermediate sublayer <NUM> until a desired number of sublayers is achieved. Then, the outer sublayer <NUM> may be deposited on the outermost deposited sublayer (e.g., the inner sublayer <NUM> or the intermediate sublayer <NUM>).

In some examples, the second depositing step <NUM> comprises depositing the outer sublayer <NUM> onto the intermediate sublayer <NUM>. In illustrative examples, the second step of depositing <NUM> includes repeating the steps of depositing the inner sublayer <NUM>, the intermediate sublayer <NUM>, and the outer sublayer <NUM> until a desired number of sublayers is achieved. Optionally, a final outer sublayer <NUM> is deposited on the outermost sublayer (e.g., the inner sublayer <NUM>, the intermediate sublayer <NUM>, or the outer sublayer <NUM>).

In some examples, the second depositing step <NUM> comprises depositing a zirconium nitride inner sublayer <NUM> onto the bonding layer <NUM>, depositing a niobium nitride intermediate sublayer <NUM> on the zirconium nitride inner sublayer <NUM>, and depositing a zirconium nitride outer sublayer <NUM> on the niobium nitride intermediate sublayer <NUM>.

In some examples, the second depositing step <NUM> is performed to produce a number of alternating sublayers of the zirconium nitride inner sublayer <NUM> and the niobium nitride intermediate sublayer <NUM>. In some examples, the steps of depositing the zirconium nitride inner sublayer <NUM> and the niobium nitride intermediate sublayer <NUM> are repeated until a desirable thickness is obtained. In some examples, the thickness is up to <NUM>.

In some examples, the second depositing step <NUM> deposits an outer sublayer <NUM> of zirconium nitride for subsequent processing.

In some examples, the step of depositing <NUM> is performed by PVD. In some examples, the first depositing step <NUM> is performed by a magnetron sputter system. In other examples, PVD may be performed using HiPIMS, IBAD, or other deposition systems.

In some examples, the oxidizing step <NUM> oxidizes a portion of the intermediate layer <NUM> to form the outer layer <NUM>. In some examples, the oxidizing step <NUM> is performed as described in <CIT> and <CIT>. In some examples, the oxidizing step <NUM> oxidizes at least a portion of the outer surface <NUM> of the intermediate layer <NUM>. In some examples, the oxidizing step <NUM> oxidizes at least a portion of the zirconium nitride outer sublayer <NUM> into oxidized zirconium thus forming the outer layer <NUM>. In some examples, the oxidizing step <NUM> oxidizes, partially or completely, the exposed surface of the zirconium nitride outer sublayer <NUM> into monoclinic oxidized zirconium. In some examples, the outer layer <NUM> comprises zirconium oxynitride. In some examples, the outer layer <NUM> comprises at least about <NUM>% zirconium oxynitride.

In some examples, the oxidizing step <NUM> is performed by heating an environment comprising oxygen. In some examples, the environment is at a temperature of least <NUM> or about <NUM>. In some examples, the environment is at a temperature of about <NUM> to about <NUM>. In an illustrative example, the environment comprises about <NUM>% oxygen in argon. In some examples, the oxidizing step <NUM> is performed for about <NUM> hours.

In alternative examples, the process <NUM> comprises a step of depositing the outer layer <NUM> (not shown). The step of depositing the outer layer <NUM> is performed by PVD, which may be performed using a magnetron sputter system. In other examples, PVD may be performed using HiPIMS, IBAD, or other deposition systems. In some examples, the step of depositing the outer layer <NUM> deposits a layer of ceramic, for example zirconium oxide.

In some examples, the deposited zirconium oxide forming the outer layer <NUM> comprises tetragonal, monoclinic, or cubic zirconium oxide. In some examples, the deposited zirconium oxide forming the outer layer <NUM> comprises tetragonal, monoclinic, or cubic zirconium oxynitride.

In some embodiments, the coating <NUM> is configured to resist chipping when a force is applied. For example, the embodiment of <FIG>, shows the ability of a multi-layer coating <NUM> to resist chipping and arrest cracking when a force of about <NUM> N is applied. Cracking occurs when the tensile strength of the material fails and begins to fracture. As is illustrated in <FIG>, the niobium sublayer arrests the cracks that are forming in the zirconium nitride sublayers. Compare the toughness and ductility to <FIG>. As illustrated in <FIG>, a monolayer of zirconium nitride developed much longer cracks compared to the multilayer coating (i.e., Sample <NUM> discussed below) in <FIG>.

In the following Examples, a series of monolayer zirconium nitride (ZrN) coatings with a niobium (Nb) bonding layer were produced and tested. Additionally, various multilayer Nb/ZrN coatings of varying architecture and thickness were produced and tested. Table <NUM> provides information on each sample. Sample coatings <NUM>-<NUM> used a Nb bonding layer of about <NUM> to <NUM> to facilitate adhesion between the Ti-6Al-4V substrate and the coating. The coatings were prepared by deposition using either magnetron sputtering with enrichment of the plasma with ions produced by thermionic emission (Sample <NUM>) from electrodes using the chamber walls as the anode (Plasma Enhanced Magnetron Sputtering), or via unbalanced magnetron sputtering to achieve the same objective of increasing the ionization rate of the plasma. The unbalanced magnetron deposition was performed on a Flexicoat <NUM> platform. Deposition parameters were selected from a series of experimental runs performed prior to producing the test samples described below.

Monolayer (Samples <NUM>-<NUM>): Ti-Al6-V4 ("Ti-<NUM>-<NUM>") coupons were polished to less than <NUM> roughness average (Ra) and were cleaned in preparation for thin film deposition. Four monolayer ZrN coatings with thicknesses ranging from <NUM> pms to <NUM>µms were produced by unbalanced magnetron sputtering in a Flexicoat <NUM> coating platform. Coating thickness was verified by examination of cross sections produced by either mounting and cross sectioning or by Focused Ion Beam (FIB) followed by examination in a scanning electron microscope (SEM).

Multilayer (Samples <NUM>-<NUM>): Ti-<NUM>-<NUM> coupons were polished to less than <NUM> Ra and were cleaned in preparation for thin film deposition. A series of multilayer Nb/ZrN coatings were produced by unbalanced magnetron sputtering in a Flexicoat <NUM> coating platform. Thickness of the various sublayers within the intermediate layer were determined by examination of cross sections produced by either mounting and cross sectioning or by FIB sectioning followed by examination in an SEM. All multilayered coatings (i.e., Samples <NUM>-<NUM>) had <NUM> sublayers, or described below as <NUM> bilayers, of Nb/ZrN with Nb representing <NUM>-<NUM>% of the bilayer thickness. Sample <NUM>, designated ML-nom is a coating designed as having a potential nominal thickness with each Nb/ZrN bilayer having a thickness of about <NUM>, a ZrN outer layer thickness of about <NUM>, and a Nb bonding layer thickness of about <NUM>. This coating is shown in cross-section in <FIG> with the layer thicknesses summarized in Table <NUM>. Three additional multilayer (ML) coatings were produced by growing all layers by <NUM>% (ML+ <NUM>), shrinking all layers by <NUM>% (ML-<NUM>), and shrinking all layers by <NUM>% (ML-<NUM>) as compared to ML-nom (Sample <NUM>). Samples <NUM>-<NUM> are summarized in Table <NUM>.

Multilayer Graded (Samples <NUM>-<NUM>): Finally, coatings with a graded stiffness were prepared in a series of <NUM> multilayer graded coatings with the same bilayer number (i.e., <NUM>) of the non-graded structures described above, but with the % Nb in the first bilayer set to about <NUM>% of the bilayer thickness and then reduced by <NUM>% in subsequent bilayer's such that bilayer <NUM> contained about <NUM>% Nb. A potential nominal graded coating with <NUM> ZrN outer layer and total thickness of <NUM> was produced and is identified as MLG-Nom (i.e., Sample <NUM>) and is shown in FIB cross section in <FIG> and summarized in Table <NUM>. All layers were increased by <NUM>% (MLG+<NUM>) and reduced by <NUM>% in MLG-<NUM> with summary thicknesses shown in Tables <NUM> and <NUM>.

Control (Sample <NUM>): Samples <NUM>-<NUM> were compared to the monolayered coatings (Samples <NUM>-<NUM>) and a commercially available coating to demonstrate the advantages and improvements in the described coatings.

Scratch testing. A scratch test was developed that reproduced scratches observed on Cobalt chromium (CoCr) femoral retrievals. A diamond tip with either a <NUM> or <NUM> radius, applied loads from <NUM>- <NUM> Newtons (N) or from <NUM>-<NUM> N, respectively, to reproduce the majority of scratches on retrievals and was applied to the Monolayer and Multilayer samples described above as well as the Commercial Comparator.

The results shown in <FIG> and <FIG> and tabulated in Table <NUM> and Table <NUM>, respectively, show that the multilayer Nb/ZrN samples resisted chipping and delamination better than those produced with a monolayer of ZrN (Samples <NUM> and <NUM>) and to a similar extent as the Commercial Comparator (Sample <NUM>) of similar thickness. <FIG> shows a cross section of multilayer coating ML-Nom (Sample <NUM>) after scratch testing, which shows how the ductile Nb layers arrest cracks that begin in the harder and more brittle ZrN layers.

While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the scope of the invention are desired to be protected.

Claim 1:
An orthopaedic knee implant comprising:
a femoral component [<NUM>] configured to be coupled to a distal end of a patient's femur, the femoral component comprising
(i) a substrate [<NUM>] comprising a titanium alloy having (a) a condylar surface [<NUM>] that is curved in a sagittal plane and (b) a bone-facing surface [<NUM>] positioned opposite the condylar surface; and
(ii) a coating [<NUM>] disposed on the condylar surface, the coating comprising (a) a bonding layer [<NUM>] comprising niobium, zirconium, titanium, tantalum, platinum, molybdenum, an alloy thereof, or combinations thereof, (b) an outer ceramic layer [<NUM>], and characterized in that the coating comprises: (c) a plurality of alternating sublayers [<NUM>, <NUM>, <NUM>] positioned between and interconnecting the bonding layer and the outer ceramic layer,
wherein (i) the plurality of alternating sublayers are configured to resist crack propagation from the outer ceramic layer, the plurality of alternating sublayers include a number of metallic sublayers [<NUM>] and a number of ceramic sublayers [<NUM>] that are harder than the metallic sublayers, and (ii) the outer ceramic layer forms an outer articular surface of the femoral component and is shaped to contact a concave proximal surface of a tibial bearing.