US20120022653A1 - Composite orthopedic implant having a low friction material substrate with primary frictional features and secondary frictional features - Google Patents

Abstract

An orthopedic implant comprising a substrate material adapted to provide the orthopedic implant. The implant has a primary friction area located on or integral with the substrate material. The primary friction area defining an engagement surface having a primary frictional feature. A secondary friction area is located on or integral with the engagement surface and defining a second frictional feature. The primary friction area and the secondary friction area defining a friction interface zone between the orthopedic implant and at least one bone. The secondary friction area increases a friction of the engagement surface and modulus of elasticity to enhance the frictional engagement between the engagement surface and the at least one bone.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• The present application claims priority to provisional U.S. Application Ser. No. 61/365,912 filed Jul. 20, 2010, to which Applicant claims the benefit of the earlier filing date. This provisional application is incorporated herein by reference and made a part hereof.
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• This invention relates to a composite orthopedic implant having a low friction material substrate with primary frictional features and secondary frictional features.
• 2. Description of the Related Art
• The placement of spinal implants between vertebrae is a common surgical procedure. A number of such spinal implants, which are generally hollow and box-shaped or cylindrical, have been developed. One risk of such procedures is the post-operative expulsion or dislocation of the implanted device. There is a need to increase the frictional forces between the device and the bone surface.
• The most advantageous material for the manufacture of intervertebral spinal implants is thermoplastic polymer, of which the most commonly used is polyetheretherketone (PEEK). This material has proven biocompatibility with human tissue and is biomechanically strong enough to withstand long-term cyclical loading as occurs within the spine. This type of material has a modulus of elasticity similar to bone, reducing the probability of bone subsidence which can occur with harder metallic implants. A significant problem, however, with the use of such polymeric spinal implants is inherent low levels of bone-device surface interaction. Machined or molded polymeric materials tend to have relatively high levels of lubricity, elasticity, and smoothness which conspire to reduce friction at the bone-device interface. This can result in undesirably low frictional forces between bone and the implanted device. Several parties have attempted to address this issue by adding large frictional features to the polymer implant. These features are typically exemplified by surface teeth of various designs. Although surface teeth increase interface friction somewhat, the underlying challenges of lubricity, smoothness and elasticity remain.
• What is needed, therefore, is a polymer implant that builds upon the current state of the art.
SUMMARY OF THE INVENTION
• One object of an embodiment is to provide simple frictional features that add a metallic surface material which has features of low lubricity, low elasticity and secondary frictional features. Such a design will maintain the desirable biomechanical properties of the polymeric implant itself while addressing frictional shortcomings at the bone-device interface. Physical properties of the metallic surface can be further optimized using dispersed deposition techniques onto the polymeric substrate.
• A composite bone-device interface used, in its preferred embodiment, in an orthopedic implant for the support of spinal vertebrae. The interface is manufactured from, in its preferred embodiment, a combination of biocompatible materials, which comprise a bone-device interface zone. The interface zone comprises a relatively low friction polymeric substrate material and primary frictional features. The primary frictional features further comprise a high-friction surface material containing secondary frictional features.
• One object of one embodiment is to provide a primary friction feature in combination with a secondary friction feature.
• Another object is to provide an embodiment where the primary friction feature is integral with the body and comprises the same material as the body, such as a polymeric substrate, whereas the secondary friction feature which is integral with, applied to, deposited on or otherwise adhered to the primary friction feature is of a different substrate, such as a metal or a metal alloy.
• Still another object is to provide a surgical implant having improved frictional engagement at the bone-implant engaging interfaces.
• Still another object is to provide an embodiment wherein the secondary frictional features are plasma vapor depositions on the primary frictional features.
• Still another embodiment is to provide an implant having a body with both primary frictional features and secondary frictional features.
• Yet another object of one embodiment is to provide primary and secondary frictional features in the form of teeth or serrations that can be regular or irregular in shape, discontinuous or continuous or otherwise have different or the same shape or configuration with respect to each other.
• Another object of an embodiment is to provide secondary frictional features in the form of elongated teeth that are situated on or integral with the primary frictional features, which in one embodiment are also teeth, and which are either regular and uninterrupted or irregular and interrupted.
• In one aspect, one embodiment comprises an orthopedic implant comprising a substrate material adapted to provide the orthopedic implant, a primary friction area located on or integral with the substrate material, the primary friction area having a primary surface having a primary frictional feature and a secondary friction area located on or integral with the primary surface and defining a secondary frictional feature, the primary friction area and the secondary friction area defining a friction interface zone, the secondary friction area increasing a friction of the primary surface to enhance the frictional engagement between the primary surface and at least one bone.
• In another aspect, another embodiment comprises an orthopedic implant comprising a body comprising a composite material, a first friction area situated between the body and bone of a patient when the orthopedic implant is implanted in the patient and a second friction area associated with the first friction area for directly engaging the bone, each of the first and second friction areas for improving a frictional engagement between the bone and the orthopedic implant.
• In yet another aspect, another embodiment comprises a method for improving a frictional interface between an implant and bone of a patient, comprising the steps of processing a body to comprise a primary friction feature, and processing the body to comprise a secondary friction feature directly on the primary friction feature.
• These and other objects and advantages will be apparent from the following description, the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view of one embodiment;
• FIG. 1A is sectional view taken along the line1A-1A inFIG. 1;
• FIG. 2 is an enlarged view of a portion of the implant shown inFIG. 1 showing details of the primary friction feature and secondary friction feature;
• FIG. 3 is a perspective view of the enlargement shown inFIG. 2;
• FIG. 4 is a sectional view taken along the line4-4 inFIG. 5 illustrating the secondary friction feature in the form of a deposit or coating on the primary friction feature;
• FIG. 5 is a view of another embodiment showing the primary friction feature as teeth and the secondary friction feature as a deposit or coating;
• FIGS. 6A-6B is a view of another embodiment of the invention showing the elongated teeth that are interrupted or spaced in the direction of arrow A;
• FIG. 7 is a view of another embodiment of the invention similar toFIG. 5;
• FIGS. 8A-8B are views of the secondary friction features having a curved or serpentine shape;
• FIGS. 9A-9B illustrate an embodiment wherein the primary friction features have a curved or serpentine shape while the secondary friction features have a generally linear (FIG. 9A) shape or a curved (FIG. 9B) shape;
• FIGS. 10A-10B illustrate another embodiment similar toFIGS. 4 and 5 wherein the deposit or coating is selectively placed;
• FIG. 11 illustrates the primary friction feature and secondary friction feature in the form of teeth having different shapes, pitches, pitch thickness and the like; and
• FIGS. 12A-12B illustrate embodiments wherein the primary friction feature or secondary friction feature are interrupted (FIG. 12A) along their longitudinal length and wherein the primary friction feature is not interrupted along its longitudinal length, but the secondary friction feature is interrupted (FIG. 12B).
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
• Referring now toFIGS. 1-5, a first embodiment of anorthopedic implant10 is shown. Theorthopedic implant10 comprises abody12 that is adapted to provide or define theorthopedic implant10. In the illustration being described, theorthopedic implant10 could be a spinal implant, such as a cage, plate or other implant wherein surfaces of theorthopedic implant10 engage, for example, bone of a patient. In one application, theorthopedic implant10 is situated between adjacent vertebrae (not shown) of a patient. In the illustration being described, theorthopedic implant10 comprises thebody12 made from a substrate or composite material, such as a polymeric material. The polymeric material may be a thermoplastic material, such as polyetheretherketone (PEEK). The substrate or composite material has a low coefficient of friction with bone.
• Theorthopedic implant10 defines anorthopedic cage11 in this illustration having a plurality ofwalls14a,14b,14cand14d.Thewalls14aand14chavewindows18 and20 as shown. Theorthopedic implant10 has a plurality ofwalls21 that definetool apertures22 for receiving a tool (not shown) for placement of theorthopedic implant10, for example, between adjacent vertebrae (not shown) in the patient.
• Theimplant10 further has afirst end12aand asecond end12b.As best illustrated inFIGS. 2-5, note that theorthopedic implant10 comprises a first or primary friction area, layer or feature24 applied to, adhered to or integrally formed on each ends12aand12b.In the illustration, thebody12 defines acage11 that has four bone-engaging areas or surfaces12a1,12a2,12b1 and12b2.
• In the illustration being described, the first or primary friction area, layer or feature24 comprises or is adapted to define a first plurality of teeth orserrations26 which are integrally formed in thesurfaces12a1,12a2,12b1 and12b2 as shown. Thebody12 is machined, molded, extruded, centered, cast or has a deposited substrate that is applied to thebody12 to provide or define the first or primary friction area, layer orfeature24. Although not shown, it should be appreciated that the first or primary friction area, layer or feature24 may be separate from and non-integral with thebody12, for example, but that is secured thereto by a weld, bond adhesive or other type of fixation. In the illustration being described relative toFIGS. 1-3, the first or primary friction area, layer or feature24 comprises the first plurality of teeth orserrations26 that are integral with thebody12 and both are made of the same polymeric substrate, such as polyetheretherketone (PEEK). Alternatively, thebody12 could be made from a polymeric substrate while the first or primary friction area, layer or feature24 may comprise a metallic or metallic alloy that is applied or, adhered to or otherwise affixed or secured to thebody12. After theorthopedic implant10 is implanted into the patient, the first or primary friction area, layer or feature24 becomes situated between thebody12 and the bone of the patient, such as the adjacent vertebra (not shown).
• As mentioned earlier, the first or primary friction area, layer or feature24 comprises the first plurality of teeth orserrations26 that are integral with both ends12aand12bof thebody12, and each of the areas or surfaces12a1,12a2,12b1 and12b2 have the first plurality of teeth orserrations26. For ease of illustration, portions of the first plurality of teeth orserrations26 on thesurface12a2 are shown fragmentarily and enlarged inFIGS. 2 and 3, but it should be understood that the first plurality of teeth orserrations26 of the first or primary friction area, layer or feature24 on the other portions ofsurface12a2 and on theother surfaces12a1,12b1 and12b2 are substantially the same in this embodiment.
• Theorthopedic implant10 further comprises a second or secondary friction area, layer or feature28 associated with the first or primary friction area, layer orfeature24. In the illustration being described, the second or secondary friction area, layer or feature28 is applied to, deposited on, adhered to, bonded, located on or integral with the first or primary friction area, layer or feature24 as shown. In the illustration being shown inFIGS. 1-3, the first or primary friction area, layer or feature24 and the second or secondary friction area, layer or feature28 cooperate to define a plurality of friction interface zones30 (FIGS. 1-1A).
• The second or secondary friction area, layer or feature28 is applied to, deposited on, adhered to, located on or adhered to teeth surfaces, such assurfaces26aand26b(FIG. 2) of each of the first plurality of teeth orserrations26 on thesurfaces12a1,12a2,12b1 and12b2 where theorthopedic implant10 engages bone and increases a friction between each of the first plurality of teeth orserrations26 and the bone of the patient. It has been found that the enhanced frictional engagement facilitates maintaining the position of theorthopedic implant10 in the patient. For example, it is desirable that thecage11 illustrated inFIGS. 1 to 5 not move after it is implanted in the patient, and the second or secondary friction area, layer or feature28 enhances the frictional engagement between the first or primary friction area, layer or feature24 and the bone of the patient to prevent or minimize such movement.
• The first or primary friction area, layer or feature24 comprises a first or primary friction feature in the form of the first plurality of teeth orserrations26, and the second or secondary friction area, layer or feature28 comprises a second or secondary friction feature that enhances the orthopedic implant's10friction interface zone30. In the embodiment ofFIGS. 1-3,6A-6B,7,8A-8B,9A-9B,11 and12A-12B, the second or secondary friction area, layer or feature28 comprises a second plurality of teeth orserrations32 integral with, deposited on, adhered to or otherwise applied to one or more of the first plurality of teeth orserrations26 as shown. Thebody12, the first or primary friction area, layer or feature24 and the second or secondary friction area, layer or feature28 is manufactured from, in its preferred embodiment, a combination of bio-compatible materials, including but not limited to, at thefriction interface zone30.
• In the illustration being described, the second or secondary friction area, layer or feature28 may comprise a microscopically and/or macroscopically rough or porous surface, which enhances the frictional engagement between the first or primary friction area, layer or feature24 and the bone of the patient. The rough surface may be provided by, for example, sand blasting, coating, plasma spraying, vapor deposition, adhering a frictional layer, peening or even laser shock peening.
• The secondary friction features may comprise a machined, molded, extruded, sintered or deposited surface material. In the illustration ofFIGS. 4-5,10A and10B, the deposited surface material may comprise a coating or deposition that is sprayed onto, melted to or otherwise applied or adhered to theprimary surface26aof the first or primary friction area, layer orfeature24. In the embodiment shown inFIGS. 4,5,7 and10A-10B, the coating or deposition is a plasma vapor deposition applied using a conventional plasma vapor deposition process. Thus, it should be understood that the second or secondary friction area, layer or feature28 may be integral with, welded to, machined into, adhered to, deposited on or otherwise affixed, processed or applied to the first or primary friction area, layer orfeature24.
• In the illustrations being described, thebody12, the first or primary friction area, layer or feature24 and the second or secondary friction area, layer or feature28 may be made from the same bio-compatible material or one or more of them can comprise or be made from different bio-compatible materials. In one embodiment, each of thebody12 and the first or primary friction area, layer or feature24 are made of a bio-compatible polymeric substrate, such as polyetheretherketone (PEEK), while the second or secondary friction area, layer or feature28 is comprised of a metal or metallic alloy. In the embodiments ofFIGS. 1-5, thebody12 and the first or primary friction area, layer or feature24 are integral and monolithically formed and are made from the same PEEK material, while the second or secondary friction area, layer or feature28 is a metallic material, metal, or metallic alloy, such as titanium, cobalt or associated alloys. It should be understood that thebody12, first or primary friction area, layer or feature24 and the second or secondary friction area, layer or feature28 could be the same material, such as a polymer, a metal or metal alloy or different materials.
• Thebody12 and the first or primary friction area, layer or feature24 comprise the polymeric substrate have a relatively low modulus of elasticity and/or a modulus of elasticity equivalent to bone while the second or secondary friction area, layer or feature28 has a higher modulus elasticity and has a modulus of elasticity that is higher than bone. It should be understood, however, that both of the first or primary friction area, layer or feature24 and/or the second or secondary friction area, layer or feature28 could comprise a relatively high modulus of elasticity or a modulus of elasticity that is higher than bone if desired.
• Thus, at least one or both of the first or primary friction area, layer or feature24 or the second or secondary friction area, layer or feature28 may comprise a relatively high coefficient of friction with bone, while the underlying substrate orbody12 and the first or primary friction area, layer or feature24 may comprise a relatively low modulus of elasticity and low coefficient of friction relative to bone. In the embodiment ofFIGS. 1-5, the second or secondary friction area, layer or feature28 comprises a higher coefficient of friction and higher modulus of elasticity compared to the first or primary friction area, layer or feature24 andbody12 which facilitate the frictional engagement and locking of theorthopedic implant10 in the patient, such as between the patient's vertebra.
• Thus, it should be understood that while thebody12 and the first or primary friction area, layer or feature24 and the second or secondary friction area, layer or feature28 may be made from the same materials having the same coefficient of friction and modulus of elasticity, they could comprise different materials which have either the same or different coefficients of friction and/or the same or different moduli of elasticity. Also, the first or primary friction area, layer or feature24 and the second or secondary friction area, layer or feature28 could be different materials and their respective modulus of elasticity and coefficients of friction relative to bone may be different as mentioned earlier.
• Again, it should be understood that one advantage of the embodiments being described is that they enhance the frictional engagement of theorthopedic implant10 when it is implanted in the patient. Thus, theorthopedic implant10 having the first or primary friction area, layer or feature24 comprising the second or secondary friction area, layer or feature28 will comprise a higher modulus of elasticity and higher coefficient of friction compared to bone.
• Advantageously, the polymers or polymeric materials used in the past may be utilized in manufacturing thebody12 and the shortcomings of such materials can be used to provide theorthopedic implant10 having thebody12 that has relatively high levels of lubricity, elasticity and smoothness, but which have been adapted, machined or processed as provided herein to provide relatively high modulus of elasticity and high coefficients of friction at the orthopedic implant10-bone interface by providing the first or primary friction area, layer or feature24 with the second or secondary friction area, layer or feature28 as described herein.
• As mentioned earlier, the first or primary friction area, layer or feature24 may be machined, molded, integral extruded, sintered or deposited onto thebody12. The first or primary friction area, layer or feature24 may be separate from or integral with thebody12 as mentioned earlier. Likewise, the second or secondary friction area, layer or feature28 may be machined, molded, extruded, sintered or deposited directly on the first or primary friction area, layer or feature24 and may also be separate from or integral with it. For example, the second or secondary friction area, layer or feature28 may be sprayed onto, deposited on, melted to, or otherwise applied to or adhered to the first plurality of teeth orserrations26 surfaces, such assurfaces26aand26bof each of the first plurality of teeth orserrations26, and/or on eachsurface12a1,12a2,12b1 and12b2 having the first or primary friction area, layer orfeature24, thereby enhancing the frictional engagement between theorthopedic implant10 and the bone. As mentioned earlier, the second or secondary friction area, layer or feature28 may be deposited on these surfaces using a plasma vapor deposition process.
• Returning to the embodiment ofFIGS. 1-3, the first or primary friction area, layer or feature24 comprises the first plurality of teeth orserrations26 that have peaks and valleys in cross section and are elongated, with each tooth or serration being generally the same in shape and dimension. Likewise, the second or secondary friction area, layer or feature28 is defined by the second plurality of teeth orserrations32 that are machined into, integral with, adhered to or applied directly to thesurfaces26aand26bof the first plurality of teeth orserrations26 as illustrated inFIGS. 1-3. In the illustration being described, the plurality ofteeth32 are thermally bonded, adhered, impregnated, embedded on or in into theteeth26. For ease of illustration,FIG. 2 shows bonding of the teeth orserrations32 to teeth orserrations26 with an adhesive37, but it should be understood that the teeth may be adhered by other means. As with the first plurality of teeth orserrations26, the second plurality of teeth orserrations32, such asteeth32aand32binFIG. 2, may each comprise generally the same shape and be elongated along the longitudinal axis and continuous as shown inFIG. 3. In other words, the first and second pluralities of teeth orserrations26 and32 may be regular in shape.
• Note that the first plurality of teeth orserrations26 are elongated and comprisesurfaces26aand26bcomprising the rows or strips33 of the second plurality of teeth orserrations32. The rows or strips33 are made of metal or a metal alloy, such as titanium or other biocompatible substance capable of providing a high-friction layer, in the illustration and adhered to or overmolded with thebody12.
• In the illustration, theorthopedic implant10 is inserted into the patient and the first or primary friction area, layer or feature24 and the second or secondary friction area, layer or feature28 onsurfaces12a1,12a2,12b1 and12b2 frictionally engage bone to secure theorthopedic implant10 in the patient.
• FIGS. 6-9B and11-12B illustrate other embodiments with like parts being identified with the same part numbers except that one or more legends or prime marks (“′”) have been added to distinguish the various embodiments of these figures.
• Note that the first plurality of teeth orserrations26′ inFIG. 11 comprises different cross-sectional shapes and sizes. Thus, the first and second pluralities of teeth orserrations26′ and32′ may be adapted to be irregular in shape, and the first plurality of teeth orserrations26′ inFIG. 11 could comprise different cross-sectional shapes and sizes. For example, note thattooth26c′ has a different shape and size compared totooth26d′.
• Likewise, the shape or size of each individual tooth, such asteeth32a′ and32b′ (FIG. 11) of the second plurality of teeth orserrations32′ may be different. Thus, the individual teeth in each of the first and second plurality of teeth orserrations26′ and32′ could be the same or have different shapes, and they could have different pitches, depths, widths and the like and will be described later herein.
• As mentioned, while the embodiment inFIGS. 1-3 illustrate that each of the first plurality of teeth orserrations26 and the second plurality of teeth orserrations32 are generally regular and uninterrupted as shown, but it should be understood that either at least one of both of the first and second pluralities of teeth orserrations26 and32 may be non-elongated and interrupted. For example,FIG. 12A illustrates that both the first plurality of teeth orserrations26″ and the second plurality of teeth orserrations32″ that are situated on or integral with each of the first plurality of teeth orserrations26′ are not continuous and are interrupted along their longitudinal axis.FIG. 12B illustrates an embodiment where only the second plurality of teeth orserrations32″ is interrupted, but not the first plurality of teeth orserrations26″. Alternatively, while the embodiments shown inFIGS. 12A and 12B illustrates first and second pluralities of teeth orserrations26″ and32″ being interrupted along their longitudinal axis, it should be understood that there may be a mixture of interrupted and uninterrupted teeth if desired.
• FIGS. 6A-6B illustrate still another embodiment wherein the second plurality of teeth orserrations32″″ are spaced or interrupted in the direction of arrow A inFIG. 6A-6B as shown. In this regard, it should be appreciated that one or both surfaces of each tooth, such assurfaces26a″″ and26b″″ inFIGS. 6A-6B, are shown as having at least one or a plurality of the second plurality of teeth orserrations32″″ mounted thereon or integral therewith. They are separately shown, but it should be understood that either one or both surfaces of the plurality of teeth orserrations26″″, such assurfaces26a″″ and26b″″, may either have or not have less teeth or one or more of the second plurality of teeth orserrations32″″.
• Still other embodiments are shown inFIGS. 8A-8B and9A-9B wherein the second plurality of teeth orserrations32″″ are shown in a curved or serpentine and non-linear shape. It should be understood that the first plurality of teeth orserrations26″″ could also be provided in a serpentine or curved shape, with the second plurality of teeth orserrations32″″ as shown. Although not shown, the first plurality of teeth orserrations26″″ could be generally serpentine or curved (FIGS. 9A-9B) with the second plurality of teeth orserrations32″″ also having a serpentine or curved shape.FIGS. 8A-8B illustrate the first teeth orserrations26 being generally linear with the second teeth orserrations32 being curved or serpentine.
• Although not shown, it should be appreciated that the embodiments shown inFIGS. 6,7,8A-8B,9A-9B and11 could be provided such that they are continuous and uninterrupted or discontinuous and interrupted. Likewise, the teeth illustrated in the figures could be provided such that the first and second pluralities of teeth orserrations26 and32 in the embodiments are not of the same cross-sectional dimension or shape. As mentioned earlier relative toFIG. 11, it should be understood that theindividual tooth26 and32 could be adapted or provided so that they are neither regular nor symmetrical when viewed in one or more of the directions in arrow B, arrow C or arrow D inFIGS. 1-1A. Thus, individual teeth of both the first plurality of teeth orserrations26 and the second plurality of teeth orserrations32 could have different pitches, depths, widths and the like.
• Referring now to the embodiment shown inFIGS. 4,5,10A and10B, the second or secondary area, layer or feature28 may be provided in the form of a deposit orcoating40. As with prior embodiments, those parts that are the same or similar to the parts shown inFIGS. 1-1A are identified with the same part number except that prime marks (“′″”) has been added to the part numbers inFIGS. 4 and 5 and a mark (“VI”) has been added to those parts in the embodiment ofFIGS. 10A and 10B. As mentioned earlier, the second or secondary friction area, layer or feature28′″ coating ordeposit40′″ could be deposited onto, sprayed onto, melted onto or otherwise applied to the first or primary area, layer or feature24′″. In the illustration being described relative toFIGS. 4 and 5, thecoating40′″ comprises a plurality ofparticles42′″ that are deposited onto, adhered to or otherwise applied tosurfaces12a1′″,12a2′″,12b1′″ and12b2′″. In this embodiment, thecoating40′″ is applied using a plasma layer deposition
• In this regard, thebody12′″ defines theorthopedic implant10′″ for implanting into the patient. The first or primary area, layer or feature24′″ in this embodiment is similar to the embodiment inFIGS. 1-1A in that each surface12a1′″,12a2′″,12b1′″ and12b2′″ has or defines a plurality of teeth orserrations26′″. In the illustration being described, each of the plurality of teeth orserrations26′″ comprises a first surface26e′″ (FIG. 4) and thesecond surface26f′″ as shown having the coating ordeposit40′″ ofparticles42′″. Note also that areas or surfaces12a3′″,12a4′″,12b3′″ and12b4′″ (FIG. 5) also have the coating ordeposit40′″ ofparticles42. In the illustration being described, the coating ordeposit40′″ is titanium, cobalt or associated alloys. As previously mentioned, the teeth orserrations26 may be asymmetrical to enhance frictional engagement.
• Thus, each of theends12a′″ and12b′″ in the illustration being described comprise the coating ordeposit40′″ ofparticles42′″. In the illustration shown inFIGS. 4 and 5, note that the layer or coating46′″ is continuous over the first or primary area, layer or feature24′″ and onends12a′″ and12b′″, but it should be understood that the ends12a′″ and12b′″ could be spot coated, and less than the entire first or primary area, layer or feature24′″ may have no deposit or coating thereon. This is illustrated inFIGS. 10A-10B where some of the areas of the first teeth orserrations26, such as theareas50, may not comprise the deposit or coating as shown. Stated another way, thecoating40^VIordeposit40′″ may be selectively provided or applied to those surfaces of theorthopedic implant10′″ that engage bone.
• In the embodiment ofFIG. 7, the surfaces, such assurfaces32b^VIIand32c^VIIof each of the second plurality of teeth orserrations32^VIIcomprises a deposit or coating ordeposit40^VIIofparticles42^VIIsimilar to that shown inFIG. 5. Thus, it should be understood that the embodiment shown inFIGS. 4 and 5 illustrates the second or secondary area, layer or feature28′″ comprising the deposit or coating as shown, whereas the embodiment illustrated inFIG. 7 shows the first or primary area, layer or feature24^VIIhaving the first plurality of teeth orserrations26^VIIhaving the second or secondary area, layer or feature28^VIIin the form of the second plurality of teeth orserrations32^VIIwhich themselves have the coating ordeposit40^VIIofparticles42^VII.
• In the illustrations being described, anyparticles42^VIIthat are applied, sprayed, adhered, coated, deposited or melted onto at least one of the first or primary area, layer or feature24^VIIor the second or secondary area, layer or feature28^VIImay be round, not round or circular or non-circular, coarse, acyclic, and may form a continuous layer or discontinuous or discreet layer on all or only a portion of the first or primary area, layer or feature24^VIIor the second or secondary area, layer orfeature28^VII. As mentioned earlier, the first or primary area, layer or feature24^VIIand the second or secondary area, layer or feature28^VIImay be comprised of the same substance or material or they could comprise different materials, such as a metallic or metallic alloy as mentioned earlier herein, or a thermal plastic such as PEEK. In the illustration ofFIGS. 4,5,7 and10A-10B, the layer or coating46′″ is a metallic coating of titanium, cobalt or associated alloys deposited on the first plurality of teeth orserrations26′″ using plasma vapor deposition.
• Advantageously, the second or secondary area, layer or feature in all embodiments augments at least a portion or all of the external first or primary area, layer or feature, such as thesurfaces26a,26bof the one or more of the first plurality of teeth orserrations26 in the embodiment ofFIGS. 1-3 in order to enhance or add high friction to the engagement surfaces of theorthopedic implant10. While traditional implants have engagement surfaces that engage bone, the embodiments described herein improve the frictional engagement between the bone and theorthopedic implant10 by adding the second or secondary area, layer or feature28 which provides improved frictional engagement between the frictional surfaces of theorthopedic implant10 and bone.
• Advantageously, one advantage of theorthopedic implant10 as described herein is that it improves the inherently low levels of bone-orthopedic implant10 interface and surface interaction. The primary frictional features described herein add a surface material, such as a metallic surface material, to the first or primary friction area, layer or feature24 which provides low lubricity, low elasticity and the secondary frictional features defined by the second or secondary friction area, layer orfeature28. The embodiments described provide or comprise a design that will maintain the biomechanical properties of theorthopedic implant10 while addressing frictional shortcomings of theorthopedic implant10 and the interfaces between the bone and the implants of the past.
• While the system, apparatus and method herein described constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to this precise system, apparatus and method, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

Claims (76)

1. An orthopedic implant comprising:

a substrate material adapted to provide the orthopedic implant;

a primary friction area located on or integral with said substrate material, said primary friction area having a primary surface having a primary frictional feature; and

a secondary friction area located on or integral with said primary surface and defining a secondary frictional feature;

said primary friction area and said secondary friction area defining a friction interface zone, said secondary friction area increasing a friction of said primary surface to enhance the frictional engagement between said primary surface and at least one bone.

2. The orthopedic implant as recited inclaim 1 wherein said primary friction area having a primary friction surface that is at least one of machined, molded, extruded, sintered or deposited substrate.

3. The orthopedic implant as recited inclaim 2 wherein said deposited substrate is a polymeric substrate.

4. The orthopedic implant as recited inclaim 2 wherein said primary friction surface defines a plurality of teeth or serrations.

5. The orthopedic implant as recited inclaim 4 wherein said secondary friction area that is at least one of machined, molded, extruded, sintered or deposited substrate.

6. The orthopedic implant as recited inclaim 4 wherein said secondary friction area comprises at least one of a microscopically or macroscopically rough surface.

7. The orthopedic implant as recited inclaim 1 wherein said secondary friction area is regular in shape.

8. The orthopedic implant as recited inclaim 1 wherein said secondary friction area is irregular in shape.

9. The orthopedic implant as recited inclaim 1 wherein said substrate material is made from a thermoplastic.

10. The orthopedic implant as recited inclaim 9 wherein said thermoplastic is a polyetheretherketone (PEEK).

11. The orthopedic implant as recited inclaim 1 wherein a modulus of elasticity of said substrate material is less than or equivalent to bone.

12. The orthopedic implant as recited inclaim 11 wherein said substrate material has a low coefficient of friction with bone.

13. The orthopedic implant as recited inclaim 1 wherein at least one of said primary friction area or said secondary friction area being made from a metal or metallic alloy.

14. The orthopedic implant as recited inclaim 1 wherein at least one of said primary friction area or said secondary friction area having a modulus of elasticity that the same as or greater than bone.

15. The orthopedic implant as recited inclaim 11 wherein said at least one of said primary friction area or said secondary friction area having a modulus of elasticity that the same as or greater than bone.

16. The orthopedic implant as recited inclaim 1 wherein at least one of said primary friction area or said secondary friction area comprising a higher coefficient of friction with bone.

17. The orthopedic implant as recited inclaim 1 wherein at least one of said primary friction area or said secondary friction area having a modulus of elasticity that the same as or greater than bone.

18. The orthopedic implant as recited inclaim 1 wherein said primary friction area comprising a higher coefficient of friction with bone and said secondary friction area comprising a higher coefficient of friction than said primary friction area.

19. The orthopedic implant as recited inclaim 1 wherein said primary friction area having a modulus of elasticity that the same as or greater than bone and said secondary friction area having a modulus of elasticity that is the same or greater than said primary friction area.

20. The orthopedic implant as recited inclaim 1 wherein said secondary frictional feature is integral with, welded to, adhered to or otherwise affixed to said primary frictional feature.

21. The orthopedic implant as recited inclaim 1 wherein said secondary frictional feature is sprayed onto, melted to or applied to said primary friction area.

22. The orthopedic implant as recited inclaim 21 wherein said secondary frictional feature are defined by particles that are at least one of round, not round or acicular, circular, coarse, acyclic.

23. The orthopedic implant as recited inclaim 22 wherein said particles are continuous or discontinuous or discrete on at least a portion of said primary frictional feature.

24. The orthopedic implant as recited inclaim 1 wherein said secondary frictional feature defines a plurality of teeth, points or peaks on said primary friction area.

25. The orthopedic implant as recited inclaim 24 wherein said plurality of teeth, points or peaks are neither regular nor symmetrical.

26. The orthopedic implant as recited inclaim 24 wherein said plurality of teeth, points or peaks are regular and symmetrical.

27. The orthopedic implant as recited inclaim 1 wherein said primary frictional feature and said secondary frictional feature are made from different materials.

28. The orthopedic implant as recited inclaim 1 wherein said primary frictional feature and said secondary frictional feature are made from the same materials.

29. The orthopedic implant as recited inclaim 1 wherein said at least one of said primary frictional feature, said secondary frictional feature or said substrate material is made from a different material than the others.

30. The orthopedic implant as recited inclaim 1 wherein said secondary frictional feature increases a coefficient of friction of said orthopedic implant and bone.

31. The orthopedic implant as recited inclaim 1 wherein said orthopedic implant is a spinal implant.

32. The orthopedic implant as recited inclaim 31 wherein said spinal implant is a cage.

33. The orthopedic implant as recited inclaim 1 wherein said secondary frictional feature is a deposit onto said primary surface.

34. The orthopedic implant as recited inclaim 33 wherein said deposit is a plasma vapor deposition deposit.

35. The orthopedic implant as recited inclaim 33 wherein said primary surface defines a plurality of teeth or serrations and said deposit is applied to surfaces of one or more of said plurality of teeth or serrations.

36. An orthopedic implant comprising:

a body comprising a composite material;

a first friction area situated between the body and bone of a patient when the orthopedic implant is implanted in the patient; and

a second friction area associated with said first friction area for directly engaging said bone,

each of said first and second friction areas for improving a frictional engagement between said bone and said orthopedic implant.

37. The orthopedic implant as recited inclaim 36 wherein said body and said first friction area comprise have a modulus of elasticity that is lower than a modulus of elasticity of said second friction area.

38. The orthopedic implant as recited inclaim 36 wherein said second friction area defines a frictional engaging surface that increases a coefficient of friction between said first friction area and said bone.

39. The orthopedic implant as recited inclaim 36 wherein body is made from a polymeric material, and at least one of said first or second friction areas comprises a metallic or metallic alloy.

40. The orthopedic implant as recited inclaim 38 wherein said first friction area defines a plurality of teeth or serrations and said second friction area defines a layer or coating thereon.

41. The orthopedic implant as recited inclaim 40 wherein said second friction area is at least one of machined, molded, extruded, sintered or deposited substrate.

42. The orthopedic implant as recited inclaim 40 wherein said second friction area comprises at least one of a microscopically or macroscopically rough surface.

43. The orthopedic implant as recited inclaim 36 wherein said second friction area is uninterrupted.

44. The orthopedic implant as recited inclaim 36 wherein said second friction area is irregular in shape.

45. The orthopedic implant as recited inclaim 36 wherein said composite material is made from a thermoplastic.

46. The orthopedic implant as recited inclaim 45 wherein said thermoplastic is a polyetheretherketone (PEEK).

47. The orthopedic implant as recited inclaim 36 wherein a modulus of elasticity of said composite material is less than or equivalent to bone.

48. The orthopedic implant as recited inclaim 47 wherein a coefficient of friction associated with said composite material and bone is lower than a coefficient of friction between said second friction area and said bone.

49. The orthopedic implant as recited inclaim 36 wherein each of said first friction area and said second friction area are made from a metal or metallic alloy and said body is made of a polymer.

50. The orthopedic implant as recited inclaim 36 wherein each of said first friction area or said second friction area have a modulus of elasticity that is the same as or greater than bone.

51. The orthopedic implant as recited inclaim 47 wherein each of said first friction area and said second friction area comprise a higher coefficient of friction with bone.

52. The orthopedic implant as recited inclaim 36 wherein said second friction area is integral with, welded to, adhered to or otherwise affixed to said first friction area.

53. The orthopedic implant as recited inclaim 36 wherein said second friction area is sprayed onto, melted to, adhered to or applied to said first friction area.

54. The orthopedic implant as recited inclaim 53 wherein said second friction area is defined by particles that are at least one of round, not round, circular, coarse, acyclic.

55. The orthopedic implant as recited inclaim 54 wherein said particles are continuous or discontinuous or discrete on at least a portion of said first friction area.

56. The orthopedic implant as recited inclaim 36 wherein said second friction area defines a plurality of points or peaks on said first friction area.

57. The orthopedic implant as recited inclaim 56 wherein said plurality of points or peaks are neither regular nor symmetrical.

58. The orthopedic implant as recited inclaim 56 wherein said plurality of points or peaks are regular and symmetrical.

59. The orthopedic implant as recited inclaim 36 wherein said orthopedic implant is a spinal implant.

60. The orthopedic implant as recited inclaim 59 wherein said spinal implant is a cage.

61. The orthopedic implant as recited inclaim 36 wherein said second friction area is a deposit onto said first friction area.

62. The orthopedic implant as recited inclaim 61 wherein said deposit is a plasma vapor deposition deposit.

63. The orthopedic implant as recited inclaim 61 wherein said first friction area defines a plurality of teeth or serrations and said deposit is applied to surfaces of one or more of said plurality of teeth or serrations.

64. A method for improving a frictional interface between an implant and bone of a patient, comprising the steps of:

processing a body to comprise a primary friction feature, and

processing said body to comprise a secondary friction feature directly on said primary friction feature.

65. The method as recited inclaim 64 wherein said primary friction feature has a primary friction surface that is at least one of machined, molded, extruded, sintered or deposited substrate.

66. The method as recited inclaim 65 wherein said least one of machined, molded, extruded, sintered or deposited substrate is a polymeric substrate.

67. The method as recited inclaim 65 wherein said primary friction surface defines a plurality of teeth or serrations.

68. The method as recited inclaim 64 wherein said secondary friction feature that is at least one of machined, molded, extruded, sintered or deposited substrate.

69. The method as recited inclaim 64 wherein said secondary friction feature comprises at least one of a microscopically or macroscopically rough surface.

70. The method as recited inclaim 64 wherein said secondary friction feature is regular in shape.

71. The method as recited inclaim 64 wherein said secondary friction feature is irregular in shape.

72. The method as recited inclaim 65 wherein said least one of machined, molded, extruded, sintered or deposited substrate has a low coefficient of friction with bone.

73. The method as recited inclaim 65 wherein at least one of said primary friction surface or said secondary friction feature being a deposit on said primary friction surface of a metal or metallic alloy.

74. The method as recited inclaim 65 wherein said secondary friction feature defines a plurality of teeth, points or peaks on said primary friction surface.

75. The method as recited inclaim 64 wherein said method comprises the step of:

depositing said secondary friction feature onto said primary friction feature.

76. The method as recited inclaim 75 wherein said depositing step is performed using plasma vapor deposition.

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