(12) Unlted States Patent
`(10) Patent No.:
`US 9,308,093 B1
`
`Lyren
`(45) Date of Patent:
`Apr. 12, 2016
`
`USOO9308093B1
`
`(54) HIP IMPLANT WITH AN INTERFACE THAT
`CONNECTS A METAL NECK BODY TO A
`POROUS BONE FIXATION BODY
`
`(71) Applicant: Four Mile Bay, LLC, Wadsworth, OH
`(US)
`
`(72)
`Inventor: Philip Scott Lyren, Hong Kong (CN)
`( * ) Notice:
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`U’S'C' 154(1)) by 0 days.
`(21) Appl.No.: 14/878,092
`
`(22)
`
`Filed:
`
`Oct. 8, 2015
`
`Related U'S'Apphcatlon Data
`(63) Continuation of application No. 13/947,069, filed on
`Jul. 21, 2013, now Pat. No. 9,265,612, which is a
`continuation of application No. 11/409,611, filed on
`Apr. 24, 2006, now Pat. No. 8,506,642, which is a
`continuation of application No. 10/446,069, filed on
`May 273 2003, now abandoned.
`
`(51)
`
`(2006.01)
`(2006.01)
`(2006.01)
`(2006.01)
`
`Int- Cl-
`A61F 2/36
`A61F 2/30
`322F 7/04
`A6117 2/28
`(52) U_s_ C1.
`CPC ........... A61F 2/3601 (2013.01); A61F 2/30767
`(2013.01); BZZF 7/04 (2013.01); A61F
`2002/28] 7 (2013.01); A61F 2002/30013
`(2013.01); A61F 2002/3092 (2013.01); A6IF
`
`2002/30] 25 (2013.01); A6IF 2002/30] 56
`(2013.01); A6IF 2002/30]58(2013.01);A61F
`2002/3033] (2013.01); A6IF 2002/30354
`(2013.01);A6]F 2002/30377 (2013.01);A6IF
`2002/30403 (2013.01); A6IF 2002/30677
`(2013.01); A6IF 2002/30968 (2013.01); A6IF
`2002/3625 (2013.01);A61F2310/00023
`(2013.01)
`(58) Egg 0f Class1ficil6t11()1:n2S()e)2121'/gl;25. A61F 2002/3631'
`A61F 2/3662; A61F 2002/3678
`See application file for complete search history.
`
`(56)
`
`References Cited
`US. PATENT DOCUMENTS
`
`6,361,566 B1*
`
`3/2002 Al-Hafez .................. A61F 2/32
`623/2215
`
`* cited by examiner
`
`Primary Examiner 7 Yashita Sharma
`
`Assistant Examiner 7 Daniel Bissing
`
`(57)
`
`ABSTRACT
`
`A hip implant haVing two distinct bodies, a neck body and a
`bone fixation body. The neck body is formed from a solid
`metal and has an interface for connecting to a femoral ball.
`The bone fixation body has an elongated shape and is formed
`as a porous structure that is inserted into an intramedullary
`canal Ofa Patient
`
`15 Claims, 3 Drawing Sheets
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`\ w82
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`ZIMMER EXHIBIT 1001
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`US 9,308,093 B1
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`HIP IMPLANT WITH AN INTERFACE THAT
`CONNECTS A METAL NECK BODY TO A
`POROUS BONE FIXATION BODY
`
`FIELD OF THE INVENTION
`
`The disclosure herein generally relates to hip implants for
`osseointegration into bone and, more particularly, to hip
`implants having a porous body.
`
`BACKGROUND OF THE INVENTION
`
`Much effort has been directed to integrating hip implants
`into surrounding bone. Ideally, a hip implant would be placed
`into the femur, and thereafter bone would readily grow into
`the surface of the implant. To achieve this objective, many
`different surface technologies have been applied to hip
`implants. In some instances, the surface of the implant is
`roughened, grit-blasted, plasma-sprayed, or microtextured.
`In other instances, the surface is coated with a biological
`agent, such as hydroxylapatite (known as HA). In all of these
`instances, the goal is the same: Produce a surface on the hip
`implant into which surrounding bone will grow or bond.
`Porous coatings have also been applied to surfaces of hip
`implants. These coatings are advantageous since bone will
`indeed grow into a portion of the outer most surface of the
`implant. Osseointegration, to a limited extent then, has been
`achieved with porous coated surfaces. These surfaces though
`are far from ideal in terms of accepting and encouraging bone
`growth into the body of the implant.
`As one disadvantage, porous surfaces are often thin coat-
`ings applied to the metallic substrate of the implant. Bone
`surrounding the implant can only grow into the thin coating
`itself. Bone cannot grow through the coating and into the
`metallic substrate. The depth of bone growth into the implant
`is limited to the depth of the porous coating. Bone simply
`cannot grow completely through the implant or deeply into
`the body of the implant.
`It therefore would be desirable to have a hip implant that
`offers optimum anchoring in bone with bone growth into a
`porous body.
`
`SUMMARY OF THE INVENTION
`
`The present invention is directed toward a femoral hip
`implant for integrating with surrounding bone. In one exem-
`plary embodiment, the implant includes two separate and
`distinct bodies, a neck body and a bone fixation body.
`Together, these bodies form a complete femoral hip implant.
`The neck body is located at the proximal end ofthe implant
`and includes an interface adapted to connect with a femoral
`ball component. In an exemplary embodiment, this interface
`comprises an elongated cylindrical shaft or neck adapted to
`matingly engage with a cylindrical recess in the femoral ball
`component.
`In one exemplary embodiment, the neck body is formed of
`a solid metal piece, such as titanium, titanium alloy, or other
`metals or alloys suitable for a hip prosthesis. The body is
`formed from a machining process and has a base portion that
`may comprise a collar. The neck extends outwardly away
`from the base portion.
`The bone fixation body is formed of a porous metal, such as
`titanium or other metals or alloys suitable for a hip prosthesis.
`In one exemplary embodiment, the body is formed with a
`sintering process, is completely porous, and does not include
`a metal substrate. In cross section then, the body has a porous
`structure with no solid metal substrate.
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`The neck body (formed of solid metal) and the bone fixa-
`tion body (formed of a completely porous structure) are per-
`manently connected together. When connected, the two bod-
`ies form a hip implant. In one exemplary embodiment, these
`two bodies are connected with a sintering process.
`In one exemplary embodiment, the bone fixation body
`portion of the hip implant is completely porous. This porous
`structure extends entirely through the body of the implant
`along the region where the implant engages femoral bone. As
`such,
`the depth of bone growth into the implant is not
`restricted to a thin porous coating. Instead, bone can grow
`deeply into the body of the implant or completely into and
`even through the body of the implant. The implant, then, can
`become fully integrated into surrounding bone with the struc-
`ture of bone dispersed throughout the body of the implant.
`In one exemplary embodiment, the geometric structure of
`the porous body may be shaped and sized to emulate the shape
`and size of natural bone surrounding the implant. Specifi-
`cally, the porous structure of the bone fixation body thus
`replicates the porous structure of natural bone itself. The
`porous structure, thus, readily accepts and encourages sur-
`rounding bone to grow into and even through the body of the
`implant.
`In one exemplary embodiment, the bone fixation body may
`be doped with bone growth agents to enhance and stimulate
`bone growth. These agents can be placed throughout the bone
`fixation body so bone grows deeply into the implant or com-
`pletely through the implant. Bone growth, as such, is not
`restricted to the surface of the implant.
`As noted, the porous structure of the implant enables bone
`to grow deeply into or completely through the implant itself.
`Growth deep into the body of the implant provides an
`extremely strong interface between the implant and surround-
`ing natural bone. As such, the likelihood that the implant will
`loosen is greatly reduced. Further,
`the overall
`long-term
`acceptance of the implant in the bone is increased. Further
`yet, the porous structure ofthe bone fixation body reduces the
`overall weight of the hip implant.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a side view of one embodiment of a hip implant of
`an exemplary embodiment of the present invention.
`FIG. 2 is a cross-sectional view of the implant of FIG. 1
`embedded in the intramedullary canal of a femur.
`FIG. 3 is a side view of another exemplary embodiment of
`a hip implant of the present invention.
`FIG. 4 is a cross-sectional view of FIG. 3 showing the hip
`implant embedded in the intramedullary canal of a femur.
`FIG. 5 is a side cross-sectional view of yet another exem-
`plary embodiment of a hip implant of the present invention.
`FIG. 6 is a side view ofyet another exemplary embodiment
`of the present invention.
`FIG. 7 is a top view of a horizontal cross section of an
`exemplary embodiment of the present invention.
`FIG. 8 is a top view of a horizontal cross section of another
`exemplary embodiment of the present invention.
`FIG. 9 is a top view of a horizontal cross section of yet
`another exemplary embodiment of the present invention.
`
`DETAILED DESCRIPTION
`
`Referring to FIGS. 1 and 2, a hip implant 10 is shown
`according to an exemplary embodiment of the invention.
`Implant 1 0 is preferably constructed ofa biocompatible mate-
`rial such as titanium, titanium alloy, or other metals or alloys
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`US 9,308,093 B1
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`3
`suitable for a hip prosthesis. Implant 10 comprises two pri-
`mary components or bodies, a neck body 14 and a bone
`fixation body 16.
`The neck body 14 is located at the proximal end 18 of the
`hip implant 10 and functions to connect the hip implant 10 to
`a spherically shaped femoral ball 19 and acetabular compo-
`nent (not shown). The neck body extends from a flat or planar
`distal end surface 21 to a proximal end surface 23. Further, the
`neck body has a base portion 20 that includes a collar 22
`adapted to seat against a resected or end portion ofa femur. An
`interface is adapted to connect the neck body to the femoral
`ball. A neck portion 24 extends outwardly from the base
`portion 20. This neck portion has a short cylindrical configu-
`ration and has an end 26 with a slight taper. This end 26 is
`adapted to be received in a correspondingly shaped and sized
`cylindrical recess 30 in the femoral ball 19. Together, end 26
`and recess 30 form a Morse taper connection.
`Preferably, the neck body 14 is formed of a biocompatible
`metal, such as a solid metal piece of titanium, titanium alloy
`or other metals or alloys suitable for a hip prosthesis. The
`body can be machined to have a size and shape shown in the
`figures or other sizes and shapes adapted for use as a hip
`implant.
`The bone fixation body 16 has an elongated tapering shape
`that extends from a flat or planar proximal end surface 40 to a
`rounded distal end surface 42. The distal end surface 21 of
`
`neck body 14 connects or fuses to the proximal end surface 40
`of the bone fixation body 16 at a junction 44.
`In the exemplary embodiments of FIGS. 1 and 2, bone
`fixation body 16 is formed from a porous metal, such as
`titanium. The body has a completely porous structure that
`extends throughout the entire body from the proximal end
`surface 40 to distal end surface 42. Specifically, as shown in
`FIG. 2, body 16 does not include a solid metal substrate.
`FIG. 2 shows the implant 10 embedded in a femur 50 of a
`patient. In this embodiment, the implant is embedded into the
`intramedullary canal 52 of the femur. The length of the bone
`fixation body 16 extends along the region where the implant
`contacts surrounding bone. As shown, the collar 22 seats
`against a resected end 56 ofthe femur above an entrance 57 to
`the intramedullary canal 59. In this embodiment, the bone
`fixation body 16 extends into the intramedullary canal, and
`the neck body 14 extends outwardly from the resected end of
`the intramedullary canal and femur. Further, the proximal end
`surfaced 40 is adjacent the entrance 57 to the intramedullary
`canal.
`
`As noted, the bone fixation body 16 has a porous structure
`that extends throughout the body from the proximal end sur-
`face to the distal end surface. By “porous,” it is meant that the
`material at and under the surface is permeated with intercon-
`nected interstitial pores that communicate with the surface.
`The porous structure can be formed by sintering titanium,
`titanium alloy powder, metal beads, metal wire mesh, or other
`suitable materials, metals, or alloys known in the art.
`The porous structure ofbody 16 is adapted for the ingrowth
`of cancellous and cortical bone spicules. In the exemplary
`embodiment, the size and shape of the porous structure emu-
`lates the size and shape of the porous structure of natural
`bone. Preferably, the average pore diameter of body 16 is
`about 40 um to about 800 um with a porosity from about 45%
`to 65%. Further, the interconnections between pores can have
`a diameter larger than 50-60 microns. In short, the geometric
`configuration of the porous structure should encourage natu-
`ral bone to migrate and grow into and throughout the entire
`body 16.
`Although specific ranges are given for pore diameters,
`porosity, and interconnection diameters,
`these ranges are
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`exemplary and are applicable to one exemplary embodiment.
`In other embodiments, these ranges could be modified, and
`the resulting hip implant still within the scope of the inven-
`tion.
`
`Preferably, body 16 is created with a sintering process. One
`skilled in the art will appreciate that many variations exist for
`sintering, and some of these variations may be used to fabri-
`cate the present invention. In the exemplary embodiment, the
`neck body is formed from a solid piece of metal and prepared
`using conventional and known machining techniques. Next, a
`ceramic mold is provided. The mold has a first cavity that is
`sized and shaped to match the size and shape of the bone
`fixation body. In this first cavity, the sintering material can be
`placed. The mold also has a second cavity that is adjacent and
`connected to the first cavity. This second cavity is sized and
`shaped to receive the neck body. The neck body is positioned
`in the second cavity such that the distal end surface is adjacent
`and continuous with the first cavity.
`The sintering material is then placed into the first cavity.
`This material may be a titanium alloy powder, such as Ti-6Al-
`4V. Some of this powder will contact the distal end surface of
`the neck body. The mold is then heated to perform the sinter-
`ing process. During this process, as the material in the first
`cavity heats and sinters, the bone fixation body forms and
`simultaneously bonds or fuses to the distal end surface of the
`neck body.
`The size and shape of the pores and porous structure pro-
`duced in the first cavity depend on many factors, These factors
`include, for example, the temperature obtained in the fumace,
`the sintering time, the size and shape of sintering material, the
`composition ofthe sintering material, and the type of ceramic
`mold used. These factors (and others) can be varied to pro-
`duce a bone fixation body in accordance with the present
`invention. Further, these factors (and others) can be varied to
`produce a strong bond between the bone fixation body and
`neck body.
`Once the sintering process is finished, the neck body is
`directly fused to the bone fixation body. These two bodies are
`now permanently connected together to form the hip implant.
`In the aforementioned sintering process, the bone fixation
`body simultaneously forms and attaches to the neck body.
`One skilled in the art though will appreciate that each ofthese
`bodies can be fabricated independently and subsequently
`connected together. If the bodies are made separately, then
`they may be attached or fused together using known welding
`or brazing techniques, for example.
`In FIG. 1, for example, the bone fixation body has an
`elongated tapering body with a slight bow. The bone fixation
`body, though, may have other configurations and still be
`within the scope of the invention. The size and shape of the
`body depend on the size and shape of the cavity of the mold
`during the sintering process. This cavity can be shaped, for
`example, to emulate the natural size, shape, and contour of a
`human intramedullary canal. As such, the bone fixation body
`will more naturally fit into the intramedullary canal and con-
`form to the natural anatomical contours of a human patient.
`FIGS. 3 and 4 show another hip implant 50 according to an
`exemplary embodiment of the invention. With some differ-
`ences, implant 50 is similarly configured to the implant 10. As
`one difference, the neck body 60 of implant 50 has two
`different and distinct regions on its outer surface. A first
`region 62 has a smooth outer surface. A second region 64 has
`a bone-engaging surface that is contiguous and adjacent to the
`first region 62 on one side and contiguous and adjacent the
`porous bone fixation body 66 on the other side. The second
`region is non-porous and is shaped as a band that extends
`completely around the neck body. This second region can be
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`US 9,308,093 B1
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`5
`formed on the outer surface of the neck body with various
`techniques. These techniques include, for example, coating
`with HA, grit-blasting, etching, micro-texturing, other non-
`porous surface treatments, or combinations of these tech-
`niques. This surface 64 is provided as an intermediate zone
`between the porous body and the smooth first region 62.
`As shown in FIG. 4, the second region 64 is below collar 68
`and is positioned into the intramedullary canal to contact
`bone. Region 64, then, contacts bone, and region 62 does not
`contact bone and extends above it.
`
`FIG. 5 shows another implant 70 according to another
`exemplary embodiment of the invention. With some differ-
`ences, implant 70 is similarly configured to the implant 10. As
`one difference, neck body 72 includes a male protrusion 74
`that extends outward from base portion 76. This protrusion 74
`is adapted to extend partially into the bone fixation body 78 of
`implant 70.
`The protrusion 74 forms a core for the bone fixation body.
`As shown in FIG. 5, this protrusion extends past the proximal
`end surface 80 and into the bone fixation body. The depth of
`the protrusion into the bone fixation body can be increased or
`decreased in various embodiments and still remain within the
`
`scope of the invention. For example, the protrusion can par-
`tially extend into the bone fixation body and remain substan-
`tially near the proximal end surface. Alternatively, the protru-
`sion can extend farther into the bone fixation body toward the
`distal end surface 82. In this latter embodiment, the protrusion
`gradually tapers as it extends toward the distal end surface.
`The size and shape of the protrusion can also have various
`embodiments and still remain within the scope of the inven-
`tion. For example,
`the protrusion can be cylindrical or
`polygonal, such as rectangular or square. Other configura-
`tions are possible as well; the protrusion can taper or have
`longitudinal ribs placed along its outer surface. The size and
`shape of the protrusion can have various embodiments to
`serve various functions. For example, the protrusion can be
`sized and shaped to provide a strong connection between the
`neck body and bone fixation body. The protrusion can be
`sized and shaped to provide an anti-rotational
`interface
`between the neck body and bone fixation body. Further, the
`protrusion can be sized and shaped to provide additional
`strength to the bone fixation body or more equally or effi-
`ciently distribute loads from the neck body to the bone fixa-
`tion body. Other factors as well may contribute to the design
`of the protrusion.
`FIG. 6 shows another implant 90 according to an exem-
`plary embodiment of the invention. Implant 90 has a bone
`fixation body 92 with an outer surface that has a plurality of
`undulations 94, such as hills and valleys. These undulations
`may be provided as tiny ripples or waves. Alternatively, the
`undulations may be larger and more rolling. Regardless, the
`undulations are adapted to firmly secure the implant into the
`intramedullary canal of the femur after the implant is placed
`therein.
`
`As shown in FIG. 6, the undulations extend along the entire
`length of the bone fixation body 92 from the proximal end
`surface 96 to the distal end surface 98. In alternative embodi-
`
`ments, the undulations do not extend along the entire length
`ofthe bone fixation body, but partially extend along this body.
`FIGS. 7-9 show various longitudinal cross-sectional
`shapes of the bone fixation body for different exemplary
`embodiments of the invention. The bone fixation body may
`have one single longitudinal cross-sectional shape, or the
`body may have numerous different longitudinal cross-sec-
`tional shapes. FIGS. 7-9 represent examples of some of these
`shapes.
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`FIG. 7 shows a trapezoidal longitudinal cross-sectional
`shape. FIG. 8 shows a triangular longitudinal cross-sectional
`shape. FIG. 9 shows an elliptical or oval longitudinal cross-
`sectional shape.
`The bone fixation body can be adapted to induce bone
`growth partially into or entirely through the body. The body,
`for example, can be doped with biologically active sub-
`stances. These substances may contain pharmaceutical
`agents to stimulate bone growth all at once or in a timed-
`release manner. Such biological active substances are known
`in the art.
`
`Although illustrative embodiments have been shown and
`described, a wide range of modifications, changes, and sub-
`stitutions is contemplated in the foregoing disclosure; and
`some features of the embodiments may be employed without
`a corresponding use of other features. Accordingly,
`it is
`appropriate that the appended claims be construed broadly
`and in a manner consistent with the scope ofthe embodiments
`disclosed herein.
`What is claimed is:
`
`1. A method, comprising:
`machining a neck body from solid metal to have a base
`portion, a neck portion that extends outwardly from the
`base portion and includes a cylindrical configuration
`with a taper that receives a femoral ball, and a male
`protrusion that extends outwardly from the base portion
`oppositely from the neck portion and has an elongated
`shape that tapers and has a polygonal shape in a cross-
`sectional view;
`fabricating, separately from the neck body, a bone fixation
`body that is formed of a porous metal structure without
`a solid metal substrate but with the porous metal struc-
`ture that extends throughout the bone fixation body, has
`a size and a shape that emulate a size and a shape of a
`porous structure of natural human bone, has a trapezoi-
`dal shape in a cross-sectional view, and has a tapering
`body with an external bow; and
`permanently connecting, after the bone fixation body is
`separately fabricated from the neck body, the bone fixa-
`tion body to the neck body at an interface where the male
`protrusion extends into and engages the bone fixation
`body and forms a core for the bone fixation body, the
`bone fixation body abuts the base portion of the neck
`body, and the bone fixation body abuts the polygonal
`shape of the male protrusion in order to provide anti-
`rotation at the interface between the neck body and the
`bone fixation body.
`2. The method of claim 1, wherein the bone fixation body
`has a size and a shape to distribute loads from the neck body
`to the bone fixation body.
`3. The method of claim 1, wherein the bone fixation body
`has a size and a shape that emulate a size and a shape of a
`human intramedullary canal.
`4. The method of claim 1, wherein the bone fixation body
`is fused to the male protrusion ofthe neck body after the bone
`fixation body is formed.
`5. The method of claim 1, wherein the bone fixation body
`is bonded to the male protrusion of the neck body after the
`bone fixation body is formed.
`6. The method of claim 1, wherein the male protrusion also
`includes a circular shape in a cross-sectional view.
`7. A method, comprising:
`machining, from solid metal, a neck body that includes a
`base portion, a neck portion that extends outwardly from
`the base portion and has a cylindrical configuration with
`a taper that receives a femoral ball, and a male protrusion
`that extends outwardly from the base portion oppositely
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`7
`from the neck portion and has an elongated shape that
`tapers and has a non-circle shape in a cross-sectional
`view;
`making, separately from the neck body, a bone fixation
`body that is formed of a completely porous metal struc-
`ture without a solid metal substrate, has a size and a
`shape that emulate a size and a shape of a porous struc-
`ture of natural human bone, has a trapezoidal shape in a
`cross-sectional view, and has a tapering body with an
`external bow; and
`permanently attaching, after the bone fixation body is sepa-
`rately made from the neck body, the bone fixation body
`to the neck body at an interface that occurs where the
`male protrusion extends into and engages the bone fixa-
`tion body to form a core for the bone fixation body,
`where the bone fixation body engages the base portion of
`the neck body, and where the bone fixation body engages
`the non-circle shape ofthe male protrusion and provides
`anti-rotation at the interface where the neck body and the
`bone fixation body attach.
`8. The method of claim 7, wherein the bone fixation body
`has a size and a shape to distribute loads from the neck body
`to the bone fixation body.
`9. The method of claim 7, wherein the bone fixation body
`has a size and a shape that emulate a size and a shape of a
`human intramedullary canal.
`10. The method of claim 7, wherein the bone fixation body
`is fused to the male protrusion ofthe neck body after the bone
`fixation body is formed.
`11. The method of claim 7, wherein the bone fixation body
`is bonded to the male protrusion of the neck body after the
`bone fixation body is formed.
`12. The method of claim 7, wherein the male protrusion
`also includes a circular shape in a cross-sectional view.
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`13. A method, comprising:
`machining a neck body from solid metal to have a base
`portion, a neck portion that extends outwardly from the
`base portion and includes a cylindrical configuration
`with a taper that receives a femoral ball, and a male
`protrusion that extends outwardly from the base portion
`oppositely from the neck portion and has an elongated
`shape that tapers and has a polygonal shape in a cross-
`sectional view;
`fabricating, separately from the neck body, a bone fixation
`body that has a tapering cylindrical body with an exter-
`nal bow on one side and with a trapezoidal shape in a
`cross-sectional view and that is formed of a porous metal
`structure without a solid metal substrate such that the
`porous metal structure extends throughout the bone fixa-
`tion body, has a porosity with values that include 45% to
`65%, and has a size and a shape that emulate a size and
`a shape of a porous structure ofnatural human bone; and
`permanently connecting, after the bone fixation body is
`separately fabricated from the neck body to have the
`tapering cylindrical body with the external bow on one
`side and with the trapezoidal shape, the bone fixation
`body to the neck body to form a hip implant such that the
`male protrusion forms a core for the bone fixation body,
`the bone fixation body abuts the base portion of the neck
`body, and the bone fixation body abuts the polygonal
`shape of the male protrusion in order to provide anti-
`rotation between the neck body and the bone fixation
`body.
`14. The method of claim 1, wherein the porous metal
`structure is fabricated to have a porosity with values that
`include 45% to 65%.
`
`15. The method of claim 7, wherein the porous metal
`structure is made to have a porosity with values that include
`45% to 65%.
`
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`Page 8 of 8
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