Patent Description:
A variety of different implants are used in the body. Implants used in the body to stabilize an area and promote bone ingrowth provide both stability (i.e. minimal deformation under pressure over time) and space for bone ingrowth.

Some implants include portions that are inserted within recesses in bone. In some cases, at least a portion of an implant receiving recess may be generally preformed in the bone. For example, at least a portion of an implant receiving recess may be formed by a medullary cavity. In such cases, tools may be used to drill or ream out the cavity further. In other cases, the recess is completely formed in the bone with tools. The portions of implants that are inserted within recesses in bone often include structural features that facilitate bone ingrowth and securing the implant within the bone. For example, some implants include texture on the bone contacting surface. Some implants include porous surfaces, or gaps between structural members that permit bone ingrowth.

In some cases the inner surfaces of the recess within the bone may have irregularities due to the natural shape of the bone and/or imperfections in the surfaces prepared by the tools. Such irregularities can reduce the amount of surface contact between the bone and the implant, which can limit the effectiveness of the mechanical fixation of the implant within the bone.

<CIT> shows an implant, comprising: a body including a substrate and a bone interfacing lattice disposed on the substrate; wherein the bone interfacing lattice includes at least two layers of elongate curved structural members; wherein the at least two layers of elongate curved structural members include a first layer adjacent the substrate and a second layer adjacent the first layer; and wherein the layers have different porosities, but the layers have a modulus of elasticity that is the same as bone.

<CIT> shows an implant, comprising: a body including a substrate and a bone interfacing lattice disposed on the substrate; wherein the bone interfacing lattice includes at least two layers of elongate curved structural members; and wherein the at least two layers of elongate curved structural members include a first compressible layer adjacent the substrate and a second compressible layer adjacent the first compressible layer. <CIT> shows an implant according to the preamble of claim <NUM>. There, the first and second layers of elongate structural members are stacked on each other, but not intermingled.

The present invention provides an implant according to claims <NUM> and <NUM>.

Other systems, methods, features and advantages of the embodiments will be, or will become, apparent to one of ordinary skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description and this summary, be within the scope of the embodiments, and be protected by the following claims.

The components in the figures are not necessarily to scale, with emphasis instead being placed upon illustrating the principles of the embodiments.

The embodiments described herein are directed to implants including portions for insertion within recesses in bone. The portions configured for insertion within the recesses each include a body having a substrate or central portion and a multi-layer bone interfacing lattice. The layers of the bone interfacing lattice may include elongate curved structural members. Such structural members may have any of a variety of curved configurations. For example, the structural members may include portions that are helical, spiraled, coiled, sinusoidal, arched, or otherwise curved. Examples of such curved configurations are provided in the following applications.

In addition to the various provisions discussed below, any of the embodiments disclosed herein may make use of any of the body/support structures, frames, plates, coils or other structures disclosed in McShane III et al. , <CIT> and titled "Implant with Protected Fusion Zones,". For purposes of convenience, this application will be referred to throughout the present application as "The Protective Fusion Zones application.

Also, any of the embodiments disclosed herein may make use of any of the body/support structures, elements, frames, plates or other structures disclosed in <CIT> titled "Implant with Arched Bone Contacting Elements,".

Also, any of the embodiments disclosed herein may make use of any of the body/support structures, elements, frames, plates or other structures disclosed in <CIT> and titled "Implant with Structural Members Arranged Around a Ring," and which is referred to herein as "The Ring application.

Also, any of the embodiments disclosed herein may make use of any of the body/support structures, elements, frames, plates, or other structures disclosed in <CIT> titled "Coiled Implants and Systems and Methods of Use Thereof," and which is referred to herein as "The Coiled Implant Application.

Also, any of the embodiments disclosed herein may make use of any of the body/support structures, elements, frames, plates, or other structures disclosed in <CIT> entitled "Implant with Bone Contacting Elements Having Helical and Undulating Planar Geometries,".

Also, any of the embodiments disclosed herein may make use of any of the body/support structures, elements, frames, plates, or other structures disclosed in <CIT> entitled "Corpectomy Implant,".

Also, any of the embodiments disclosed herein may make use of any of the body/support structures, elements, frames, plates, or other structures disclosed in <CIT> entitled "Implant with Supported Helical Members,".

As used herein, the term "fixedly attached" shall refer to two components joined in a manner such that the components may not be readily separated (for example, without destroying one or both components).

For purposes of clarity, reference is made to various directional adjectives throughout the detailed description and in the claims. As used herein, the term "anterior" refers to a side or portion of an implant that is intended to be oriented towards the front of the human body when the implant has been placed in the body. Likewise, the term "posterior" refers to a side or portion of an implant that is intended to be oriented towards the back of the human body following implantation. In addition, the term "superior" refers to a side or portion of an implant that is intended to be oriented towards a top (e.g., the head) of the body while "inferior" refers to a side or portion of an implant that is intended to be oriented towards a bottom of the body. Reference is also made herein to "lateral" sides or portions of an implant, which are sides, or portions, facing along a lateral direction of the body (and which correspond with the left or right sides of a patient).

An implant may also be associated with various reference planes or surfaces. As used herein, the term "median plane" refers to a vertical plane which passes from the anterior side to the posterior side of the implant, dividing the implant into right and left halves, or lateral halves. As used herein, the term "transverse plane" refers to a horizontal plane that divides the implant into superior and inferior portions. As used herein, the term "coronal plane" refers to a vertical plane located in the center of the implant that divides the implant into anterior and posterior halves. In some embodiments, the implant is symmetric about one or more of these planes.

<FIG> is a schematic cutaway cross-sectional view of a bone having a recess and a longitudinal cross-sectional view of a portion of an implant configured to be inserted into the recess in the bone. As shown in <FIG>, a portion of an implant <NUM> may include a body <NUM>. Body <NUM> may include a substrate <NUM> and a bone interfacing lattice <NUM> disposed on substrate <NUM>.

Bone interfacing lattice <NUM> may be fixedly attached to substrate <NUM> in any suitable manner. For example, in some embodiments, body <NUM> may be 3D printed, such that substrate <NUM> and bone interfacing lattice <NUM> are a continuous unitary structure. In other embodiments, bone interfacing lattice <NUM> may be sintered, welded, thermally bonded, or otherwise joined to substrate <NUM>.

<FIG> also shows a portion of a bone <NUM>, illustrated in a cutaway cross-sectional view. As shown in <FIG>, bone <NUM> includes a recess <NUM>. In some cases, recess <NUM> may be substantially naturally occurring in the bone. For example, in some cases, recess <NUM> may be a medullary cavity. In order prepare a medullary cavity for insertion of an implant, bone marrow may be removed from the medullary cavity. In addition, portions of the cancellous bone lining the medullary cavity may also be removed, to provide an inner bone surface that is primarily cortical bone. In other cases, recess <NUM> may be wholly formed by surgical tools. For example, in some cases, a recess may be bored, reamed, or otherwise surgically formed in cortical bone or trabecular bone.

Portions of implants configured to be inserted into recesses in bone may include provisions to promote bone ingrowth. For example, bone interfacing surfaces of implants may include porous structures, such as a lattice of elongate curved structural members. In some embodiments, the porous structures may include provisions to maximize the amount of surface contact between the porous bone interfacing lattice of the implants and the bone. For example, in some embodiments, the bone interfacing lattice may include portions that are conformable to the interior wall of the recess in the bone.

As shown in <FIG>, in some embodiments, body <NUM> of implant <NUM> may have a substantially elongate shape configured to be inserted into recess <NUM> in bone <NUM>. For example, body <NUM> may be elongate along a central longitudinal axis <NUM>. Body <NUM> of implant <NUM> is illustrated as being a substantially conical shape. Other elongate shapes are also envisioned, including substantially cylindrical rods or posts. Further, any suitable cross-sectional shape may be used, including circular, oval, square, rectangular, triangular, and any other suitable shape.

The bone interfacing lattice may include at least two layers having differing deformabilities. For example, inner layers (positioned closer to the substrate) may have a low deformability (or even substantially no deformability in practical use). Outer layers (positioned further from the substrate) may have greater deformability. Accordingly, these outer layers may deform in order to conform to the inner wall of the recess in the bone. The bone interfacing lattice includes at least two layers of elongate curved structural members. In some embodiments, the bone interfacing lattice may have three or more layers of elongate curved structural members, wherein the three or more layers have differing deformabilities.

As shown in <FIG>, bone interfacing lattice <NUM> may include three layers. For example, a first layer <NUM> may be disposed adjacent substrate <NUM>. In addition, lattice <NUM> may include a second layer <NUM> disposed adjacent first layer <NUM> outward of first layer <NUM> relative to central longitudinal axis <NUM>. Also, lattice <NUM> may include a third layer <NUM> adjacent second layer <NUM> and outward of second layer <NUM>.

The layers of bone interfacing lattice <NUM> may be fixedly attached to one another in any suitable manner. For example, in some embodiments, body <NUM> may be 3D printed, such that the layers form a continuous unitary structure. In other embodiments, the layers may be sintered, welded, thermally bonded, or otherwise joined to one another. In addition, first layer <NUM> may be fixedly attached to substrate <NUM>.

First layer <NUM> may have a first deformability, second layer <NUM> may have a second deformability, and third layer <NUM> may have a third deformability. In some embodiments, the second deformability of second layer <NUM> may be greater than the first deformability of first layer <NUM>. In addition, the third deformability of third layer <NUM> may be greater than the second deformability of second layer <NUM>.

Each layer of the lattice structure may include a plurality of elongate curved structural members. The configuration of the elongate curved structural members may vary from layer to layer in order to provide the respective layers with differing amounts of deformability. The layers can be deformable in any of a variety of ways (e.g., elastic vs. plastic deformation) described in more detail below. In addition, the configuration of the elongate curved structural members can differ in a variety of ways to provide the variance in deformability.

In some embodiments, the respective layers may be provided with differing amounts of elastic deformability. In some embodiments, the respective layers may be provided with differing amounts of plastic deformability. In some embodiments, a given layer may be configured to maintain its thickness but deform by bending as a whole. In other cases, a layer may be configured to collapse, for example, by compressing. Thus, in some embodiments, the layers of the lattice may have different compressibilities. For example, in some embodiments, outer layers may be more compressible than inner layers. That is, the outer layers may have a greater capacity for the thickness of the layers to collapse. In some embodiments, the further the layer is from the substrate of the implant, the greater the compressibility, with the outermost (i.e., bone contacting) layer being the most compressible.

In some embodiments, a combination of varying compressibility and varying deformability may be utilized. For example, in some embodiments, an innermost layer may be substantially non-deformable, an outermost layer may be deformable by bending, but may maintain its thickness despite deforming. That is, the outermost layer may deflect inward in order to conform to the inner surface of the bone recess. In order to permit the inward deflection of the outermost layer, an intermediate layer between the innermost layer and the outermost layer may be relatively compressible. Thus, the compressible intermediate layer may collapse in various locations to accommodate the inward deflection of the outermost layer. However, since the outermost layer does not collapse to reduce its thickness, the porosity of the outermost layer may be preserved in deflected areas, which may maximize the capacity of the outermost bone contacting layer to permit bone ingrowth. Other arrangements of layers having differing deformabilities are also possible. Among other alternatives, more than three layers may be used to form the lattice. In some embodiments, different portions of the same lattice layer may have different deformabilities.

In some embodiments, the densities of the elongate curved structural members may vary. For example, outer layers may have lower densities than inner layers. For purposes of this disclosure, the term densities shall refer to ratio of open space to volume occupied by elongate curved structural members. A lower density of structural members provides a layer with greater porosity. Thus, lower densities in the outer layers provide a more porous bone contacting surface. The greater porosity may facilitate bone ingrowth. In addition, the greater porosity may enable the outer layers to maintain a desired level of porosity even when the layers are partially compressed upon implantation.

In some embodiments, the outer layers may be formed of different materials than the inner layers. For example, in some embodiments, the outer layers may be formed of more flexible or more deformable materials than the inner layers.

In some embodiments, the gauge of the elongate curved structural members may differ from layer to layer. That is, the cross-sectional size of the elongate curved structural members may be larger in some layers and smaller in other layers. For example, in some embodiments, the further from the substrate a layer is disposed, the smaller the gauge of the elongate curved structural members in the layer. The smaller gauge renders the structural members to be more deformable (plastically or elastically).

As shown in <FIG>, each of first layer <NUM>, second layer <NUM>, and third layer <NUM> are formed of elongate curved structural members. Such structural members may have any of a variety of curved configurations. For example, the structural members may include portions that are helical, spiraled, coiled, sinusoidal, arched, or otherwise curved.

The configuration of curved structural members may be regular or irregular. That is, the members may be arranged in a regular pattern or in a random arrangement. Some of the structural members within each layer may overlap or intersect with one another. In some cases, the cross-sectional size and/or shape of a structural member could vary along its length (e.g., the diameter could change along the length of a structural member).

Embodiments can include provisions for protecting bone growth along and adjacent to elongate curved structural members of an implant. In some embodiments, an elongate curved structural member can be configured with a geometry that helps to protect new bone growth in selected regions or "protected fusion zones. " In some embodiments, an elongate curved structural member can have a spiral, helical or twisted geometry that provides a series of such protected fusion zones for enhanced bone growth.

Some elongate curved structural members may have a generalized helical geometry. As used herein, a "generalized helical geometry" or "spiraling geometry" refers to a geometry where a part (portion, member, etc.) winds, turns, twists, rotates or is otherwise curved around a fixed path. In some cases, the fixed path could be straight. In other cases, the fixed path can be curved. In the present embodiments, for example, the fixed path is generally a combination of straight segments and curved segments.

Curves having a generalized helical geometry (also referred to as generalized helical curves) may be characterized by "coils," "turns," or "windings" about a fixed path. Exemplary parameters that may characterize the specific geometry of a generalized helical curve can include coil diameter (including both a major and minor diameter) and the pitch (i.e., spacing between adjacent coils). In some cases, the "amplitude" of a coil or loop may also be used to describe the diameter or widthwise dimension of the coil or loop. Each of these parameters could be constant or could vary over the length of a generalized helical curve.

Generalized helical curves need not be circular or even round. In some embodiments, for example, a generalized helical curve could have linearlysegmented shape (or locally polygonal shape) such that each "coil" or "turn" is comprised of straight line segments rather than arcs or other curved segments. Generalized helical curves may also include combinations of curved and straight segments.

The arrangement of elongate curved structural members may be designed to achieve a desired total open volume. As used herein a total open volume is the combined volume of any openings between structural members or between structural members and the substrate. This open configuration may facilitate bone growth in and through the implant. A portion, or substantially all of, the open spaces may be filled with a bone graft or bone growth promoting material prior to insertion of the implant to facilitate bone growth.

The implantation process may begin with the application of a bone growth promoting material, also referred to as a BGPM, to the implant. As used herein, a "bone growth promoting material" is any material that helps bone growth. Bone growth promoting materials may include provisions that are freeze dried onto a surface or adhered to the metal through the use of linker molecules or a binder. Examples of bone growth promoting materials are any materials including bone morphogenetic proteins (BMPs), such as BMP-<NUM>, BMP-<NUM>, BMP-<NUM>, BMP-<NUM>, and BMP-<NUM>. These are hormones that convert stem cells into bone forming cells. Further examples include recombinant human BMPs (rhBMPs), such as rhBMP-<NUM>, rhBMP-<NUM>, and rhBMP-<NUM>. Still further examples include platelet derived growth factor (PDGF), fibroblast growth factor (FGF), collagen, BMP mimetic peptides, as well as RGD peptides. Generally, combinations of these chemicals may also be used. These chemicals can be applied using a sponge, matrix or gel.

Some bone growth promoting materials may also be applied to an implantable prosthesis through the use of a plasma spray or electrochemical techniques. Examples of these materials include, but are not limited to, hydroxyapatite, beta tri-calcium phosphate, calcium sulfate, calcium carbonate, as well as other chemicals.

A bone growth promoting material can include, or may be used in combination with a bone graft or a bone graft substitute. A variety of materials may serve as bone grafts or bone graft substitutes, including autografts (harvested from the iliac crest of the patient's body), allografts, demineralized bone matrix, and various synthetic materials.

Some embodiments may use autograft. Autograft provides the implantation site with calcium collagen scaffolding for the new bone to grow on (osteoconduction). Additionally, autograft contains bone-growing cells, mesenchymal stem cells and osteoblast that regenerate bone. Lastly, autograft contains bone-growing proteins, including bone morphogenic proteins (BMPs), to foster new bone growth in the patient.

Bone graft substitutes may comprise synthetic materials including calcium phosphates or hydroxyapatites, stem cell containing products which combine stem cells with one of the other classes of bone graft substitutes, and growth factor containing matrices such as INFUSE® (rhBMP-<NUM>-containing bone graft) from Medtronic, Inc.

It should be understood that the provisions listed here are not meant to be an exhaustive list of possible bone growth promoting materials, bone grafts, or bone graft substitutes.

In some embodiments, BGPM may be applied to one or more outer surfaces of an implant. In other embodiments, BGPM may be applied to internal volumes within an implant. In still other embodiments, BGPM may be applied to both external surfaces and internally within an implant.

As shown in <FIG>, the elongate curved structural members of first layer <NUM> may have a first gauge, the elongate curved structural members of second layer <NUM> may have a second gauge, and the elongate curved structural members of third layer <NUM> may have a third gauge. As further shown in <FIG>, the second gauge may be smaller than the first gauge, and the third gauge may be smaller than the second gauge. This difference in gauges may provide each of the layers with a different deformability.

Accordingly, the dimensions of the elongate curved structural members can vary. In some embodiments, the elongate curved structural members can have cross-sectional diameters ranging between <NUM> and <NUM>. For example, in some embodiments the elongate curved structural members of first layer <NUM> may be approximately <NUM> in diameter, the elongate curved structural members of second layer <NUM> may be approximately <NUM> in diameter, and the elongate curved structural members of third layer <NUM> may be approximately <NUM> in diameter.

<FIG> is a schematic transverse cross-sectional view of the implant shown in <FIG>. As shown in <FIG>, first layer <NUM> may have a first thickness that is substantially consistent such that an outer shape of first layer <NUM> is substantially the same as the outer shape of substrate <NUM>. In addition, second layer <NUM> may have a second thickness that is substantially consistent such that the outer shape of second layer <NUM> is substantially the same as the outer shape of first layer <NUM>. Further, third layer <NUM> may have a third thickness that is substantially consistent such that the outer shape of third layer <NUM> is substantially the same as the outer shape of second layer <NUM>. In other words, in some embodiments, the interfaces between layers may be concentric.

In some embodiments, the interface between layers may have a substantially negligible thickness. In other embodiments, the interface between the first layer and the second layer is a transition region having a thickness within which the elongate curved structural members of the first layer are intermingled with the elongate curved structural members of the second layer. Similarly, the interface between the second layer and the third layer may also be a transition region having a thickness, within which the elongate curved structural members of the second layer are intermingled with the elongate curved structural members of the third layer.

Implant <NUM> may be configured to be implanted within any of a variety of bones within the body of a human or animal. In some embodiments, body <NUM> of implant <NUM> may be configured for implantation into the medullary cavity of long bones, such as the femur or humerus. In some embodiments, body <NUM> of implant <NUM> may be configured for implantation into a drilled or reamed recess in cortical or trabecular bone.

<FIG> is a schematic cross-sectional view of bone <NUM> of <FIG> with body <NUM> of implant <NUM> inserted into recess <NUM>. In addition, <FIG> is a schematic transverse cross-sectional view of bone <NUM> and implant <NUM> inserted as shown in <FIG>. As shown in <FIG>, portions of third layer <NUM> and portions of second layer <NUM> may be deformed to conform with irregularities in the inner surface of recess <NUM>. In an area where bone <NUM> protrudes into recess <NUM>, such as protrusion <NUM> in <FIG>, one or more layers of implant <NUM> may deform as shown by a deformed area <NUM> in <FIG>.

<FIG> is a schematic enlarged cross-sectional view of bone <NUM> and implant <NUM>. <FIG> generally illustrates the different gauges of the elongate structural members in first layer <NUM>, second layer <NUM>, and third layer <NUM>. It will be noted that depiction of the size, shape, and general configuration of these layers is intended to be schematic. The elongate curved structural members can have any suitable shape and arrangement. The present disclosure is directed to the properties of the multi-layer lattice in terms of the relative deformabilities of the layers.

As shown in <FIG>, one or more layers of the lattice of implant <NUM> are deformable. Protrusion <NUM> of bone <NUM> represents an irregularity in a bone recess. While surgical tools are generally able to prepare a bone recess with minimal irregularities, the relative size of protrusion <NUM> is exaggerated in <FIG> for purposes of illustration. As shown in <FIG>, two of the layers of the lattice are deformed by protrusion <NUM>, resulting in a reduction in the thickness of the two deformed layers at the location of protrusion <NUM>. In particular, first layer <NUM> has a first undeformed thickness of <NUM>, second layer <NUM> has a second undeformed thickness <NUM>, and third layer <NUM> has a third undeformed thickness <NUM>. In the deformed area, third layer <NUM> has a deformed thickness <NUM> that is smaller than third undeformed thickness <NUM>. In addition, second layer <NUM> has a deformed thickness <NUM> that is smaller than second undeformed thickness <NUM>. In some embodiments, the deformability of the layers may differ. For example, in some embodiments, third layer <NUM> may deform more than second layer <NUM>. <FIG> is a schematic enlarged view of three layers of elongate curved structural members. In some embodiments, the layers may be formed as a single unitary structure, for example, by 3D printing. As shown in <FIG>, in some embodiments, the transition between one layer to the next layer may occur in two dimensions. That is, the transition may have no thickness, such that adjacent layers are completely discreet. For example, as shown in <FIG>, a first transition <NUM> between first layer <NUM> and second layer <NUM> may have no thickness. Similarly, a second transition <NUM> between second layer <NUM> and third layer <NUM> may also have no thickness. This configuration may ensure that the deformabilities of the respective layers remain unchanged by the transitions between layers. <FIG> is a schematic enlarged view of three layers of elongate curved structural members wherein the layers intermingle with one another at the respective boundaries. <FIG> is a schematic further enlarged view of the three layers of elongate curved structural members shown in <FIG>. As shown in <FIG>, in some embodiments, the transitions between layers may have a thickness. That is, there is a portion of the lattice where elongate curved structural members from one layer intermingle with the elongate curved structural members of the adjacent layer. <FIG> illustrates first layer <NUM> as having a first thickness <NUM>, second layer <NUM> as having a second thickness <NUM>, and third layer <NUM> as having a third thickness <NUM>. As further shown in <FIG>, first layer <NUM> and second layer <NUM> intermingle to form a transition region <NUM>, which has a thickness, and therefore a volume. Similarly, second layer <NUM> intermingle with third layer <NUM> to form a second transition region <NUM>, which has a thickness, and therefore a volume. This configuration may provide the lattice with additional strength, and prevent delamination of layers.

In some embodiments, some layer transitions may have a thickness, and others may not. For example, in some embodiments, the transition between the first (innermost) layer and the second layer may have a thickness, whereas the transition between the second (middle) layer and the third (outermost) layer may not have a thickness. In such embodiments, since the first layer may not deform much, if at all, having a transition with thickness to the second layer may not unduly alter the deformability of the first layer. Whereas, for the transition between the second layer and the third layer, a transition without thickness may be preferred in order to maintain the relative deformability properties of the respective layers and the lattice as a whole.

<FIG> are schematic illustrations intended to generally illustrate a portion of an implant having a multi-layer bone interfacing lattice inserted into a portion of a bone. <FIG> are not intended to be specific to a particular type of implant or a particular type of bone. <FIG> illustrate exemplary embodiments in which such a multi-layer bone interfacing lattice may be implemented.

<FIG> is a schematic exploded view of a knee replacement implant system according to an exemplary embodiment. There are multiple components of a knee replacement system that can implement a multi-layer bone interfacing lattice. As shown in <FIG>, a knee replacement implant system <NUM> may include a femoral component <NUM> and a tibial component <NUM>. Femoral component <NUM> may be configured for mounting onto the distal end of a femur <NUM>. Femoral component <NUM> may include one or more posts <NUM> configured to be inserted into holes <NUM> in femur <NUM> which are drilled by the surgeon. Posts <NUM> may include a multi-layer bone interfacing lattice to facilitate maximum bone contacting surface within holes <NUM>. Stippling indicates general areas of posts <NUM> that may include a multi-layer bone interfacing lattice. Tibial component <NUM> may also include a post <NUM> configured for insertion into a recess <NUM> in the proximal end of a tibia <NUM>. Recess <NUM> may include a portion of the medullary cavity within the tibia, and may also be at least partially formed by the surgeon via cutting, drilling, reaming, or other bone shaping processes. Post <NUM> may also include a multi-layer bone interfacing lattice to facilitate maximum bone contacting surface within recess <NUM>. Stippling indicates general areas of post <NUM> that may include a multi-layer bone interfacing lattice.

In some embodiments, a multi-layer bone interfacing lattice may be implemented on metaphyseal sleeves. Such sleeves are utilized, for example, during revision surgeries when a significant amount of bone resorption has taken place. The sleeves take up the space between an implant post and the inner surface of the bone recess, which has become enlarged due to bone resorption and/or further reaming performed to prepare the recess for a new implant.

<FIG> is a schematic exploded view of a metaphyseal sleeve <NUM> and a tibial plateau implant <NUM>. As illustrated in <FIG>, metaphyseal sleeve <NUM> may include a central hole <NUM> configured to receive a post <NUM> of tibial plateau implant <NUM>. In addition, sleeve <NUM> may include a bone interfacing lattice configured for implantation in a proximal end of a tibia <NUM>. The lattice may include a plurality of concentric layers formed of elongate curved structural members. As shown in <FIG>, the lattice may include a first layer <NUM>, a second layer <NUM>, and a third layer <NUM>.

As further shown in <FIG>, first layer <NUM> may include elongate curved structural members having a first gauge. Second layer <NUM> may include elongate curved structural members having a second gauge. Third layer <NUM> may include elongate curved structural members having a third gauge. As shown in <FIG>, the second gauge may be smaller than the first gauge, and the third gauge may be smaller than the second gauge.

As also shown in <FIG>, in some embodiments, implant <NUM> may include an inner sleeve <NUM>. Inner sleeve <NUM> may provide a substrate layer upon which first layer <NUM> of elongate curved structural members may be formed. In addition, the inner surface of inner sleeve <NUM> may be configured to mate with the surface of post <NUM> of tibial plateau implant <NUM>. For example, the two surfaces may have textures or other features to prevent or otherwise minimize the likelihood that post <NUM> comes out of central hole <NUM>.

<FIG> is a schematic view of a hip replacement implant system according to an exemplary embodiment. As shown in <FIG>, a hip replacement implant system <NUM> may include a femoral component <NUM> and pelvic component <NUM>. Femoral component <NUM> may be configured for mounting onto the proximal end of a femur <NUM>. Femoral component <NUM> may include a post <NUM> configured to be inserted into a recess in femur <NUM>. The recess may include a portion of the medullary cavity within femur <NUM>, and may also be at least partially formed by the surgeon via cutting, drilling, reaming, or other bone shaping processes. Post <NUM> may include a multi-layer bone interfacing lattice to facilitate maximum bone contacting surface within the recess of femur <NUM>. Stippling indicates general areas of post <NUM> that may include a multi-layer bone interfacing lattice.

As shown in <FIG>, pelvic component <NUM> may be an acetabular cup configured for implantation in an acetabulum <NUM> of a patient's pelvis <NUM>. Pelvic component <NUM> may include a substantially spherical outer surface <NUM>. Outer surface <NUM> may be configured to interface with acetabulum <NUM>. Pelvic component <NUM> may be affixed to acetabulum <NUM> with several mechanisms. For example, pelvic component <NUM> may be affixed to acetabulum <NUM> with one or more screws.

In addition, the screw fixation of pelvic component <NUM> may be supplemented with bone ingrowth into outer surfaces of pelvic component <NUM>. For example, as shown in <FIG>, in some embodiments, outer surface <NUM> of pelvic component <NUM> may include a multi-layer bone interfacing lattice similar to that described in other embodiments discussed herein. The multi-layer bone interfacing lattice of outer surface <NUM> may promote bone ingrowth into outer surface <NUM>. Stippling indicates general areas of outer surface <NUM> that may include a multi-layer bone interfacing lattice.

Additionally, in some embodiments, pelvic component <NUM> may include one or more posts, such as a first post <NUM> and a second post <NUM>. Upon implantation of pelvic component <NUM>, first post <NUM> may be inserted into a first hole <NUM>, which may be drilled into acetabulum <NUM>. Similarly, upon implantation of pelvic component <NUM>, second post <NUM> may be inserted into a second hole <NUM>, which may be drilled into acetabulum <NUM>. In some embodiments, first post <NUM> and second post <NUM> may have outer surfaces including a multi-layer bone interfacing lattice similar to that described in other embodiments discussed herein. The multi-layer bone interfacing lattice of first post <NUM> and second post <NUM> may promote bone ingrowth into the surfaces of these posts, and thus, provide additional fixation of pelvic component <NUM> to pelvis <NUM>. Stippling indicates general areas of first post <NUM> and second post <NUM> that may include a multi-layer bone interfacing lattice.

<FIG> is a schematic view of a shoulder replacement implant system according to an exemplary embodiment. As shown in <FIG>, a shoulder replacement implant system <NUM> may include a humoral component <NUM> and a glenoid component <NUM>. Humoral component <NUM> may be configured for mounting onto the proximal end of a humerus <NUM>. Humoral component <NUM> may include a post <NUM> configured to be inserted into a recess in humerus <NUM>. The recess may include a portion of the medullary cavity within humerus <NUM>, and may also be at least partially formed by the surgeon via cutting, drilling, reaming, or other bone shaping processes. Post <NUM> may include a multi-layer bone interfacing lattice to facilitate maximum bone contacting surface within the recess of humerus <NUM>. Stippling indicates general areas of post <NUM> that may include a multi-layer bone interfacing lattice.

<FIG> is a schematic exploded view of the glenoid side of the shoulder replacement implant system shown in <FIG>. Glenoid component <NUM> may be configured to be implanted in glenoid cavity <NUM> of a patient's shoulder <NUM>. Glenoid component <NUM> may include a base component <NUM> and a liner <NUM>. Liner <NUM> may be a low friction material, such as plastic, which may facilitate motion against humeral component <NUM> (see <FIG>). Liner <NUM> may be attached to base component <NUM>, for example using a snap-in configuration.

Base component <NUM> may be affixed within glenoid cavity <NUM> with several mechanisms. For example, base component <NUM> may be affixed within glenoid cavity <NUM> by bone ingrowth into outer surfaces of base component <NUM>. For example, as shown in <FIG>, in some embodiments, a bone contacting surface <NUM> of base component <NUM> may include a multi-layer bone interfacing lattice similar to that described in other embodiments discussed herein. The multi-layer bone interfacing lattice of bone-contacting surface <NUM> may promote bone ingrowth into outer surface <NUM>. Stippling indicates general areas of bone-contacting surface <NUM> that may include a multi-layer bone interfacing lattice.

Additionally, in some embodiments, base component <NUM> may include one or more posts, such as a first post <NUM> and a second post <NUM>. Upon implantation of base component <NUM>, first post <NUM> may be inserted into a first hole <NUM>, which may be drilled into glenoid cavity <NUM>. Similarly, upon implantation of base component <NUM>, second post <NUM> may be inserted into a second hole <NUM>, which may be drilled into glenoid cavity <NUM>. In some embodiments, first post <NUM> and second post <NUM> may have outer surfaces including a multi-layer bone interfacing lattice similar to that described in other embodiments discussed herein. The multi-layer bone interfacing lattice of first post <NUM> and second post <NUM> may promote bone ingrowth into the surfaces of these posts, and thus, provide additional fixation of base component <NUM> to glenoid cavity <NUM>. Stippling indicates general areas of first post <NUM> and second post <NUM> that may include a multi-layer bone interfacing lattice.

<FIG> is a schematic assembled view of an ankle replacement implant system according to an exemplary embodiment. There are multiple components of an ankle replacement system that can implement a multi-layer bone interfacing lattice. As shown in <FIG>, an ankle replacement implant system <NUM> may include a tibial component <NUM> and a talar component <NUM>. Tibial component <NUM> may be configured for mounting onto the distal end of a tibia <NUM>. Tibial component <NUM> may include a baseplate <NUM> and one or more posts <NUM> extending from baseplate <NUM> and configured to be inserted into one or more recesses in tibia <NUM>. The recesses in tibia <NUM> may include a portion of the medullary cavity within the tibia, and may also be at least partially formed by the surgeon via cutting, drilling, reaming, or other bone shaping processes. Posts <NUM> may include a multi-layer bone interfacing lattice to facilitate maximum bone contacting surface within the recesses. Stippling indicates general areas of posts <NUM> that may include a multi-layer bone interfacing lattice.

Baseplate <NUM> may include a bone contacting surface having one or more recesses <NUM>. Recesses <NUM> may be at least partially filled with a multi-layer bone interfacing lattice to promote bone ingrowth.

Talar component <NUM> may also include one or more posts <NUM> configured for insertion into one or more recesses in the proximal end of a talus <NUM>. The one or more recesses may be at least partially formed by the surgeon via cutting, drilling, reaming, or other bone shaping processes. Posts <NUM> may also include a multi-layer bone interfacing lattice to facilitate maximum bone contacting surface within the recess. Stippling indicates general areas of posts <NUM> that may include a multi-layer bone interfacing lattice.

<FIG> is a schematic assembled view of an ankle fusion implant system according to an exemplary embodiment. As shown in <FIG>, an ankle fusion implant system <NUM> may include an intramedullary rod <NUM>. Intramedullary rod <NUM> may be configured for mounting onto the distal end of a tibia <NUM>. As shown in <FIG>, intramedullary rod <NUM> may also be inserted through a talus <NUM> and a calcaneus <NUM>. Intramedullary rod <NUM> may be inserted within a recess in tibia <NUM> that may include a portion of the medullary cavity within tibia <NUM>. In addition, intramedullary rod <NUM> may be inserted into recesses in talus <NUM> and calcaneus <NUM> that may be at least partially formed by the surgeon via cutting, drilling, reaming, or other bone shaping processes. Intramedullary rod <NUM> may include a multi-layer bone interfacing lattice to facilitate maximum bone contacting surface within the recesses within the tibia and ankle bones. Stippling indicates general areas of intramedullary rod <NUM> that may include a multi-layer bone interfacing lattice.

<FIG> is a schematic perspective view of an alternative intramedullary rod embodiment for an ankle fusion implant system. <FIG> shows an intramedullary rod <NUM>. Intramedullary rod <NUM> may include a plurality of elongate curved structural members <NUM>. As shown in <FIG>, structural members <NUM> may intersect at junctions <NUM> that are recessed from the outermost envelope of intramedullary rod <NUM>. Accordingly, the support member junctions are generally not located at the bone-implant interface when rod <NUM> is implanted.

<FIG> is a schematic view of a hammertoe correction implant according to an exemplary embodiment. As shown in <FIG>, a hammertoe correction implant <NUM> may be implanted into adjacent phalanges to fuse an interphalangeal joint. The outer surface of implant <NUM> may include a multi-layer bone interfacing lattice of elongate curved structural members to facilitate bone ingrowth. For example, as shown in <FIG>, implant <NUM> may include a first layer <NUM>, a second layer <NUM>, and a third layer <NUM>. In some embodiments, implant <NUM> may have a central hole <NUM>. Bone graft material may be placed in central hole <NUM> to facilitate fixation and bone ingrowth.

<FIG> depicts a substantially cylindrical embodiment having a three layer lattice. This configuration may be used for any of a number of different intramedullary rods. In some embodiments, such cylindrical implants may be used to join adjacent bones, such as phalanges in the foot (as shown in <FIG>) or the hand. In other cases, such implants may be used to repair long bones, such as the humerus, femur, tibia, and other such bones. For severe breaks, long bones may be repaired by placing a rod inside the substantially hollow bone. The three layer lattice discussed herein may facilitate fixation and bone ingrowth for such intramedullary rods.

In addition, other intramedullary implants are also possible. For example, in some embodiments, an implant having dual, concentric helical members may be utilized.

<FIG> is a schematic perspective view of another substantially cylindrical implant configured for intramedullary implantation. As shown in <FIG>, an implant <NUM> may include a first outer spiral <NUM> and first inner spiral <NUM>. In addition, implant <NUM> may include a second outer spiral <NUM> and a second inner spiral <NUM>. This dual, concentric spiral configuration may provide structural support, while maintaining a substantially hollow inner volume to receive bone graft material and/or bone ingrowth.

The inner and outer spirals may have separate starting points akin to a dual-start thread. In addition, the inner and outer spirals may be joined to one another at the ends. For example, as shown in <FIG>, first outer spiral <NUM> and first inner spiral <NUM> may be joined by a first connecting portion <NUM>. As also shown in <FIG>, second outer spiral <NUM> and second inner spiral <NUM> may be joined by a second connecting portion <NUM>.

<FIG> illustrate other views of implant <NUM>. As shown in <FIG>, longitudinal spacing <NUM> may be provided between spirals. Ain addition, as shown in <FIG>, the outer and inner spirals may be concentric. In addition, first inner spiral <NUM> and second inner spiral <NUM> may define a cylindrical central opening <NUM>. In addition, the inner spirals and outer spirals may define an annular space <NUM> between the inner spirals and the outer spirals. Central opening <NUM>, annular space <NUM>, and longitudinal spacing <NUM> may be configured to receive bone graft material and/or bone ingrowth.

<FIG> is a schematic perspective view of a substantially cylindrical intramedullary implant according to another exemplary embodiment. <FIG> shows an implant <NUM> being formed of a plurality of criss-crossing support members <NUM> forming a substantially cylindrical grid or cage having a longitudinal axis <NUM>. As shown in <FIG>, implant <NUM> may have a bend in it, such that longitudinal axis <NUM> has a curved portion. This bend may facilitate implantation into separate pieces of bone that are intended to be maintained at an angle with respect to one another.

Implant <NUM> may be configured to be placed within elongate bones, such as phalanges of the hand or foot. In some cases, implant <NUM> may be configured to be implanted in the intramedullary space of larger bones, such as the femur or humerus. In some embodiments a first end <NUM> of implant <NUM> may be inserted into a first bone or first piece of bone, and a second end <NUM> of implant <NUM> may be inserted into a separate bone or piece of bone. By inserting opposing ends of implant <NUM> into separate bones (e.g., phalanges) or pieces of bones (e.g., broken long bones), implant <NUM> may stabilize these bones to facilitate fusion of separate bones or healing of separate broken bone pieces.

In order to prevent egress of implant <NUM> after implantation, implant <NUM> may include one or more spikes <NUM>. Spikes <NUM> may be configured to facilitate insertion of implant <NUM> but prevent removal of implant <NUM> as well as preventing rotation of implant <NUM> about longitudinal axis <NUM>. For example, implant may include a first spike <NUM> located proximate first end <NUM> of implant <NUM>. First spike <NUM> may include a first surface <NUM> facing away from first end <NUM> and extending substantially perpendicularly with respect to longitudinal axis <NUM>. First spike <NUM> may also include a second surface <NUM> facing toward first end <NUM> of implant <NUM> and extending at a non-zero angle with respect to longitudinal axis <NUM>. That is, as second surface <NUM> extends away from the surface of support members <NUM>, second surface <NUM> slopes away from first end <NUM> of implant <NUM>. The slope of second surface <NUM> may facilitate insertion of implant <NUM> and the perpendicular configuration of first surface <NUM> may prevent removal of implant <NUM> from within a bone into which it has been implanted.

As shown in <FIG>, spikes <NUM> at opposing ends of implant <NUM> may have sloped surfaces facing in opposite directions. That is, the spikes closest to first end <NUM> may have sloped surfaces facing toward first end <NUM>, as with first spike <NUM>. And the spikes closest to second end <NUM> may have sloped surfaces facing toward second end <NUM>. For example, implant may include a second spike <NUM> proximate to second end <NUM> of implant <NUM>. Second spike <NUM> may include a first surface <NUM> facing away from second end <NUM> and extending substantially perpendicularly from longitudinal axis <NUM>. In addition, second spike <NUM> may include a second surface <NUM> facing toward second end <NUM> and extending at a non-zero angle with respect to longitudinal axis <NUM>.

<FIG> is a schematic lateral view of the implant shown in <FIG>. As shown in <FIG>, in some embodiments, spikes <NUM> may be disposed on opposing sides of implant <NUM>. For example, implant <NUM> may include a third spike <NUM> disposed opposite first spike <NUM>. Similarly, implant <NUM> may include a fourth spike <NUM> disposed opposite second spike <NUM>. Accordingly, in at least one plane, implant <NUM> may be substantially symmetrical about longitudinal axis <NUM>.

<FIG> is a schematic perspective view of a substantially cylindrical intramedullary implant according to another exemplary embodiment. As shown in <FIG>, an implant <NUM> may be formed of a plurality of spiral members <NUM> extending about a central longitudinal axis <NUM>. To support spiral members <NUM>, implant <NUM> may include a framework. The framework may be formed from a first substantially circular end member <NUM> and a second substantially circular end member <NUM>. A plurality of longitudinal members <NUM> may extend between first substantially circular end member <NUM> and second substantially circular end member <NUM>. Spiral members <NUM> may be supported by longitudinal members <NUM>. Implant <NUM> may have any suitable longitudinal length and radial diameter with respect to longitudinal axis <NUM>. For example, implant <NUM> may have a suitable size for implantation within small bones like phalanges or large bones such as the humerus or femur.

As illustrated in <FIG>, spiral members <NUM> may have a substantially sinusoidal configuration, deviating in and out radially with respect to longitudinal axis <NUM>. In addition, spiral members <NUM> may include a plurality of flattened surfaces <NUM> that collectively form at least a portion of the outer surface of implant <NUM>. The structural members of implant <NUM> define a central hollow cavity in the interior of implant <NUM>. The central hollow cavity may be configured to receive bone graft material.

<FIG> is another schematic perspective view of the implant shown in <FIG>. <FIG> better shows the central hollow cavity, as well as the sinusoidal configuration of spiral members <NUM>, as seen from the inside of implant <NUM>.

<FIG> is a schematic lateral view of the implant shown in <FIG>. <FIG> illustrates the angle or pitch of spiral members <NUM>. <FIG> also shows that flattened surfaces <NUM> of spiral members <NUM> alternate as to which side of longitudinal members <NUM> they are disposed. This may provide an even distribution of surface area for the outer (bone contacting) surface of implant <NUM>.

The various components of an implant may be fabricated from biocompatible materials suitable for implantation in a human body, including but not limited to, metals (e.g. titanium or other metals), synthetic polymers, ceramics, and/or their combinations, depending on the particular application and/or preference of a medical practitioner.

Generally, the implant can be formed from any suitable biocompatible, non-degradable material with sufficient strength. Typical materials include, but are not limited to, titanium, biocompatible titanium alloys (e.g. γTitanium Aluminides, Ti<NUM>-Al<NUM>-V ELI (ASTM F <NUM> and F <NUM>), or Ti<NUM>-Al<NUM>-V (ASTM F <NUM>, F <NUM> and ASTM F <NUM>)) and inert, biocompatible polymers, such as polyether ether ketone (PEEK) (e.g. PEEK-OPTIMA®, Invibio Inc and Zeniva Solvay Inc. Optionally, the implant contains a radiopaque marker to facilitate visualization during imaging.

In different embodiments, processes for making an implant can vary. In some embodiments, the entire implant may be manufactured and assembled via readditional/CNC machining, injection-molding, casting, insertmolding, co-extrusion, pultrusion, transfer molding, overmolding, compression molding, <NUM>-Dimensional (<NUM>-D) printing (including Direct Metal Laser Sintering and Electron Beam Melting), dip-coating, spray-coating, powder-coating, porouscoating, milling from a solid stock material and their combinations. Moreover, the embodiments can make use of any of the features, parts, assemblies, processes and/or methods disclosed in the "The Coiled Implant Application.

Claim 1:
An implant, comprising:
a body (<NUM>) including a substrate (<NUM>) and a bone interfacing lattice (<NUM>) disposed on the substrate;
wherein the bone interfacing lattice (<NUM>) includes at least two layers (<NUM>, <NUM>) of elongate curved structural members;
wherein the at least two layers (<NUM>, <NUM>) of elongate curved structural members include a first layer (<NUM>) adjacent the substrate (<NUM>) and configured to receive bone ingrowth and a second layer (<NUM>) adjacent the first layer (<NUM>) and configured to receive bone ingrowth;
wherein the first layer (<NUM>) has a first deformability and the second layer (<NUM>) has a second deformability; and
wherein the second deformability is greater than the first deformability such that the second layer (<NUM>) has a deformability that renders it configured to conform to an inner wall of a recess (<NUM>) within a bone (<NUM>);
characterized in that an interface between the first layer (<NUM>) and the second layer (<NUM>) is a transition region (<NUM>) having a thickness within which the elongate curved structural members of the first layer (<NUM>) are intermingled with the elongate curved structural members of the second layer (<NUM>).