US008821582B1
`
`(12) United States Patent
`US 8,821,582 B1
`(10) Patent N0.:
`
`Lyren
`(45) Date of Patent:
`Sep. 2, 2014
`
`(54) HIP IMPLANT WITH POROUS BODY
`
`(56)
`
`References Cited
`
`(76)
`
`Inventor: Philip Scott Lyren, Bangkok (TH)
`
`UHS PATENT DOCUMENTS
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`were is exeeneee er adjueeee under as
`U30 1540)) by 168 days~
`(21) Appl. N0.: 13/592,349
`,
`<22)
`Filed:
`Aug- 23, 2012,
`Related U-S- APPhcathIl Data
`<63) Continuation-impart of application NO- 11/409511:
`filed 0114131 2.4: 2006: HOW Pat N0~ 8506542: Wthh
`15 a contmuat1on of appl1catlon No. 10/446,069, filed
`on May 27, 2003, now abandoned.
`
`_
`*
`3/133; 33,13,534~~~~~~~~~~~~~~~~ 233/3332
`12333;; g .
`
`.....
`6:296:667 B1* 10/2001 Johnson et al.
`623/2361
`6,361,566 B1:
`3/2002 Al-Hafez
`623/2215
`2:912:33? 3% e 13/3882 62131211350
`::: 233/3323
`*
`.
`7,981,161 B2 *
`7/2011 Choi et al.
`......
`623/22.42
`
`3883853133 :1 e 12/3885 33%;; e121."
`::: 233/3336
`................ 623/2242
`2004/0107001 A1*
`6/2004 Cheal etal.
`.
`.
`c1ted by exammer
`
`
`
`*
`
`(51)
`
`(2006.01)
`
`Int. Cl.
`A61F 2/32
`(52) us. Cl.
`USPC ....................................................... 623/22.11
`(58) Field of Classification Search
`CPC ............ A61F 2/3 4. A61F 2002/30332' A61F
`2/3609; A61F 2/32; A61F 2220/0033; A61F
`2002/365; A61F 2220/0025; A61F 2002/3401;
`A61F 2002/3652; A61F 2002/3092
`USPC .......... 623/22.11, 22.1572326, 23.2972237,
`623/23.53723.55; 606/62768
`See application file for complete search history.
`
`Primary Examiner 7 Jan Christopher Merene
`Assistant Examiner 7 Steven Cotroneo
`
`ABSTRACT
`
`(57)
`.
`.
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`A h1p 1mplant has a neck body that connects to a bone fixatlon
`body. The bone fixation body has a porous structure with an
`elongated shape. An internal cavity is formed in the bone
`fixation body and includes a substance to stimulate bone
`growth.
`
`20 Claims, 8 Drawing Sheets
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`Page 1 of18
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`ZIMMER EXHIBIT 1024
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`ZIMMER EXHIBIT 1024
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`500A
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`500B
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`540A
`550A
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`V» £(/
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`510A
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`520A
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`530A
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`A:’/
`510B
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`520B
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`5305
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`FIG. 14A
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`FIG. 14B
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`550C 540C
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`500C
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`Ar’
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`5300
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`FIG. 140
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`FIG. 14D
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`540E
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`FIG. 14E
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`FIG. 15A
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`FIG. 15B
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`710
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`730
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`740
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`V
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`V
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`V
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`Bone from core
`\ growing to \
`natural bone
`\\\\
`Natural bone \
`k growing into
`surface of \\
`implant to core \
`L
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`FIG. 16
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`700
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`720 \
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`\Bone from 00
`\ growing to
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`\ Natural bone
`\ growing into
`\ surface of
`\ implant to core
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`US 8,821,582 B1
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`1
`HIP IMPLANT WITH POROUS BODY
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This application is a continuation-in-part of Ser. No.
`11/409,611 filed on 24 Apr. 2006 now US. Pat. No. 8,506,
`642, which is a continuing application of Ser. No. 10/446,069
`filed on May 27, 2003 now abandoned, both entitled “Hip
`Implant with Porous Body” and both being incorporated
`herein by reference.
`
`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. Porous surfaces are often thin coatings applied to
`the metallic substrate of the implant. Bone surrounding the
`implant can only grow into the thin coating itself. Bone can-
`not 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 com-
`pletely through the implant or deeply into the body of the
`implant.
`
`SUMMARY OF THE INVENTION
`
`One example embodiment is a hip implant that includes a
`bone fixation body that connects to a neck body. The bone
`fixation body is formed of a porous structure that extends
`through a center ofthe bone fixation body in a cross-sectional
`view ofthe bone fixation body. An internal cavity is located in
`the porous structure of the bone fixation body. This internal
`cavity includes a substance to stimulate bone growth.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a side view of an example embodiment of a hip
`implant.
`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 example embodiment of a
`hip implant.
`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 ofyet another example
`embodiment of a hip implant.
`FIG. 6 is a side view ofyet another example embodiment a
`hip implant.
`FIG. 7 is a top view of a horizontal cross section of an
`example embodiment.
`FIG. 8 is a top view of a horizontal cross section of another
`example embodiment.
`FIG. 9 is a top view of a horizontal cross section of yet
`another example embodiment.
`FIG. 10A is another example of a hip implant.
`
`2
`
`FIG. 10B is a cross-section taken along lines 10B-10B of
`the hip implant in FIG. 10A.
`FIG. 11A is another example of a hip implant.
`FIG. 11B is a cross-section taken along lines 11B-11B of
`the hip implant in FIG. 11A.
`FIG. 12 is a cross-section of another example of a hip
`implant.
`FIG. 13 is a cross-section of another example of a hip
`implant.
`FIG. 14A is an example ofa cross-section ofa bone fixation
`body of a hip implant.
`FIG. 14B is another example of a cross-section of a bone
`fixation body of a hip implant.
`FIG. 14C is another example of a cross-section of a bone
`fixation body of a hip implant.
`FIG. 14D is another example of a cross-section of a bone
`fixation body of a hip implant.
`FIG. 14E is another example of a cross-section ofa bone
`fixation body of a hip implant.
`FIG. 15A is an example cross-section ofa neck body ofa
`hip implant.
`FIG. 15B is an example cross-section of a bone fixation
`body of a hip implant.
`FIG. 16 is a partial cross-sectional view of a hip implant
`embedded in a femur of a patient.
`
`DETAILED DESCRIPTION
`
`In one example embodiment, a hip implant includes two
`separate and distinct bodies, a neck body and a bone fixation
`body. Together, these bodies connect together to form a femo-
`ral hip implant.
`The bone fixation body is formed of a porous structure,
`such as titanium, tantalum, or other metals, polymers, or
`alloys suitable for a hip prosthesis. The bone fixation body has
`at least one cross-section in which the porous structure is
`completely porous. This completely porous structure can
`extend through a portion of the bone fixation body (e. g.,
`throughout a cross-section) or through the entire body of the
`bone fixation body. For example in one embodiment, the bone
`fixation body is completely porous from its proximal to distal
`ends and does not include a metal substrate. In another
`
`example embodiment, a portion of the bone fixation body is
`completely porous and does not include a metal substrate. In
`at least one cross-sectional view then, the bone fixation body
`has a porous structure with no solid metal substrate.
`In one example embodiment, the porous structure extends
`entirely through a cross-section of the bone fixation body of
`the hip implant along the region where the hip implant
`engages femoral bone. As such, the depth ofbone growth into
`the hip implant is not restricted to a thin porous coating.
`Instead, bone can grow deeply into the bone fixation body of
`the hip implant or completely into and even through the bone
`fixation body of the hip implant (i.e., bone can grow from one
`side of the hip implant through its center and to another
`oppositely disposed side). The hip implant can become fully
`integrated into surrounding bone with the structure of bone
`dispersed throughout
`the bone fixation body of the hip
`implant.
`In one example embodiment, the geometric structure ofthe
`porous structure ofthe bone fixation body is shaped and sized
`to emulate the shape and size of natural bone surrounding the
`hip implant. The porous structure of the bone fixation body
`thus replicates the porous structure ofnatural bone itself. The
`porous structure readily accepts and encourages surrounding
`bone to grow into and even through the bone fixation body of
`the hip implant.
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`US 8,821,582 B1
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`3
`the bone fixation body
`In one example embodiment,
`includes an internal cavity with a substance that causes and/or
`stimulates bone growth. This internal cavity can be enclosed
`within the bone fixation body without an egress or ingress.
`Alternatively, one or more openings in the bone fixation body
`or hip implant can lead to the internal cavity.
`In one example embodiment, the bone fixation body and/or
`internal cavity include one or more substances to cause and/or
`stimulate bone growth. This sub stance can be placed through-
`out the bone fixation body and/or internal cavity so bone
`grows deeply into the hip implant or completely through the
`hip implant from one side to an oppositely disposed side.
`Bone growth, as such, is not restricted to the surface ofthe hip
`implant.
`In one example embodiment, the substance in the internal
`cavity includes a porous structure that causes and/or stimu-
`lates bone growth from within the internal cavity. Bone grows
`from the internal cavity toward an exterior surface ofthe bone
`fixation body. After the hip implant is implanted, bone can
`thus simultaneously grow from the internal cavity toward an
`exterior surface of the bone fixation body and from the exte-
`rior surface of the bone fixation body toward the internal
`cavity. New bone growth thus concurrently occurs and origi-
`nates from two separate and distinct locations (i.e., from
`locations within the hip implant and from locations exterior to
`the hip implant).
`As noted, the porous structure of the hip implant enables
`bone to grow deeply into or completely through the hip
`implant or portions ofthe hip implant. Bone growth deep into
`the body of the hip implant provides a strong interface
`between the hip implant and surrounding natural bone. As
`such,
`the likelihood that
`the hip implant will
`loosen is
`reduced. Further, the overall long-term acceptance of the hip
`implant in the bone is increased. Further yet, the porous
`structure of the bone fixation body and internal cavity reduce
`the overall weight ofthe hip implant. The size and shape ofthe
`internal cavity also enables the physical properties ofthe bone
`fixation body to more closely emulate the physical properties
`of natural bone.
`
`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
`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.
`
`10
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`15
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`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 1 6 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 pm 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 diam-
`eters, porosity, and interconnection diameters, these ranges
`are exemplary and are applicable to one exemplary embodi-
`ment. In other embodiments, these ranges could be modified,
`and the resulting hip implant still within the scope of the
`invention.
`
`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
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`US 8,821,582 B1
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`5
`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 of the 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
`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
`fixationbody. 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 partially extend into the bone fixation body
`
`6
`and remain substantially near the proximal end surface. Alter-
`natively, the protrusion can extend farther into the bone fixa-
`tion 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.
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`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-
`
`35
`
`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.
`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.
`
`FIGS. 10A and 10B show a hip implant 100 according to an
`example embodiment. The hip implant 100 comprises two
`primary components or bodies, a neck body 114 and a bone
`fixation body 116.
`The neckbody 114 is located at the proximal end 118 ofthe
`hip implant 100 and functions to connect the hip implant 100
`to a spherically shaped femoral ball and acetabular compo-
`nent. The neck body extends from one or more flat or planar
`distal end surfaces 121 to a proximal end surface 123. A neck
`portion 124 extends outwardly from a base portion 120. This
`neck portion has a short cylindrical configuration and has an
`end 126 with a slight taper. This end 126 is adapted to be
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`received in a correspondingly shaped and sized cylindrical
`recess in the femoral ball (shown in FIGS. 1 and 2).
`Preferably, the neck body 114 is formed ofa biocompatible
`metal, such as one or more of a solid metal piece of titanium,
`titanium alloy, polymer, or other metals or alloys suitable for
`a hip prosthesis. The neck body can be machined, casted,
`molded, or otherwise configured 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 116 has an elongated tapering
`shape that extends from a proximal end 140 to a rounded
`distal end 142. The proximal end includes one or more flat or
`planar surfaces 144. One or more ofthese surfaces connect to
`the distal end surfaces 121 ofthe neckbody 114 at an interface
`or junction 146.
`As shown in FIG. 10B, the bone fixation body 116 forms a
`shell 148 with a completely porous structure that extends
`throughout the entire bone fixation body from the proximal
`end 140 to the distal end 142. This shell 148 has a hollow 20
`center that forms an internal chamber or cavity 150 located
`inside the bone fixation body 116. The internal cavity 150
`extends from a location adjacent the interface 146 to the distal
`end 142. A circular opening 152 leads into the internal cavity
`150 and forms at the distal end 142 of the bone fixation body 25
`116. The internal cavity 150 is thus enclosed inside of the
`porous structure of the bone fixation body 116.
`As shown in FIG. 10B, the internal cavity 150 includes a
`substance 154 to cause or stimulate bone growth. This sub-
`stance 154 fills the internal cavity 150 from a proximal end 30
`surface of the internal cavity to an oppositely disposed distal
`end surface of the internal cavity. Alternatively, the sub stance
`can partially fill the internal cavity or be absent from the
`internal cavity.
`A shape and/or size of the internal cavity 150 can vary 35
`along its longitudinal length. In an example embodiment, this
`shape matches or emulates the external shape of the bone
`fixation body 116. As the size and/or shape of the bone fixa-
`tion body 116 changes, the size and/or shape of the internal
`cavity 150 correspondingly changes. With regard to size for 40
`example, as the cross-sectional diameter of the bone fixation
`body increases or decreases, the cross-sectional diameter of
`the internal cavity proportionally increases or decreases to
`match the increases or decreases in the diameter of the bone
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`fixation body. With regard to shape for example, the bone 45
`fixation body 116 has an elongated cylindrical or elliptical
`shape at a distal end portion 156 in cross-section. Likewise,
`the internal cavity 150 has an elongated cylindrical or ellip-
`tical shape at this distal end portion 156. At a proximal end
`portion 158, the bone fixation body has a rectangular or 50
`trapezoidal shape in cross-section. Likewise, the internal cav-
`ity 150 has a rectangular or trapezoidal shape at this proximal
`end portion 158. Thus, as the size and/or shape of the bone
`fixation body changes along its longitudinal length, the size
`and/or shape of the internal cavity can also change to match 55
`with or correspond to these changes.
`In an example embodiment, the internal cavity 150 is cen-
`trally located inside of the bone fixation body 116 such that
`the sides or walls 160 ofthe internal cavity are equally spaced
`from an external surface 162 of the bone fixation body. The 60
`walls 160 can include one or more grooves 164 formed in the
`porous structure of the bone fixation body. These grooves
`form one or more channels that extend from the circular
`
`opening 152 to an end surface 166 of the internal cavity 150.
`As shown in FIG. 10B, the internal cavity 150 has a larger 65
`diameter in cross-section adjacent the interface 146 at the
`proximal end 158 than at the distal end 156. The size of the
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`internal cavity narrows and tapers as it transitions from the
`proximal end of the hip implant toward the distal end of the
`hip implant.
`While the hip implant 100 is being positioned into the
`femur ofthe patient, bone, tissue, and/or blood enters and fills
`the internal cavity 150. As the hip implant passes into the
`medullary canal of the femur, bone, tissue, and/or blood are
`forced into the internal cavity and travel upwardly along the
`grooves 164 toward the end surface 166. The grooves guide
`and facilitate the passage ofbone, tissue, and/orblood into the
`internal cavity. For example, bone travels in the grooves 164
`from the opening 152 to the end surface 166 in order to fill or
`collect within the internal cavity 150.
`The grooves 164 can be straight and extend parallel to each
`other from the opening 152 to the end surface 166. Altema-
`tively, the grooves can be nonlinear, such as being curved or
`spiraling. Grooves facilitate the transfer of bone, tissue, and/
`orblood into the internal cavity 150 while the hip implant 100
`is being forced, pressed, or inserted into the femur. Altema-
`tively, the internal cavity 150 can be formed without grooves.
`FIGS. 11A and 11B show a hip implant 200 with a neck
`body 202 that connects to a bone fixation body 206 according
`to an example embodiment. With some differences, the hip
`implant 200 is similarly configured to the hip implant 100 in
`FIGS. 10A and 10B. As one difference, the hip implant 200
`includes an internal cavity 210 that is enclosed and trapped
`within the bone fixation body 206. One of end this internal
`cavity 21 0 is located near or adj acent ajunction 218 where the
`neck body 202 connects to a proximal end 214 of the bone
`fixation body 206. Another end of this internal cavity 210
`extends toward a distal end 216 ofthe bone fixation body 206.
`In an example embodiment, the internal cavity 210 is com-
`pletely enclosed within the bone fixation body 206. The bone
`fixationbody 206 completely surrounds the sides, the top, and
`the bottom of the internal cavity 210 (i.e., the internal cavity
`is surrounded on all sides by the porous structure). As such,
`the internal cavity 210 lacks an ingress (such as a hole or a
`passageway) for entering the cavity or an egress for exiting
`the cavity (such as a hole or a passageway). Nonetheless, the
`open-celled configuration of the porous structure of the bone
`fixation body does allow bone to grow into and through the
`bone fixation body. Thus, the internal cavity can still commu-
`nicate with the porous structure ofthe bone fixation body and
`with bone external to the bone fixation body through the
`interconnected interstitial pores to enable bone growth since
`the internal cavity is surrounded by and formed within an
`open-celled porous structure. Alternatively, the bone fixation
`body 206 includes openings, holes, and/or passageways from
`an external surface 238 to the internal cavity 210.
`As shown in FIG. 11B, the internal cavity 210 includes a
`substance 220 to cause or stimulate bone growth. This sub-
`stance 220 fills the internal cavity 210 from a proximal end
`surface 230 of the internal cavity to an oppositely disposed
`distal end surface 232 of the internal cavity. Alternatively, the
`substance can partially fill the internal cavity or be absent
`from the internal cavity.
`In one example embodiment, the substance 220 is trapped
`within the enclosed internal cavity. For example, the sub-
`stance is placed in the internal cavity during manufacturing or
`formation of the hip implant. Alternatively, the substance is
`placed in the internal cavity after the hip implant is con-
`structed. For instance, a small opening is formed through the
`hip implant, the substance is placed through the opening and
`into the internal cavity, and then the opening is sealed and/or
`closed. As yet another example, the substance is liquefied and
`forced through the interconnected interstitial pores of the
`bone fixation body and into the internal cavity.
`In this
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