United States Patent (19)
`Zolman et al.
`
`Patent Number:
`11
`(45) Date of Patent:
`
`5,018,285
`May 28, 1991
`
`54 METHOD OF CONSTRUCTING
`PROSTHETIC IMPLANT WITH WRAPPED
`POROUS SURFACE
`75) Inventors: Arden R. Zolman, Warsaw; Phillip J.
`Andersen, Silver Lake; Steven T.
`Bayne, Warsaw, all of Ind.
`73) Assignee: Zimmer, Inc., Warsaw, Ind.
`(21) Appl. No.: 463,829
`(22 Filed:
`Jan. 16, 1990
`Related U.S. Application Data
`Continuation of Ser. No. 277,525, Nov. 28, 1988, aban
`doned, which is a division of Ser. No. 88,363, Aug. 24,
`1987, abandoned.
`51) Int. Cl.......................... B23Q 9/02; B23P 19/04
`52 U.S. C. ..................................... 29/465; 29/419.1;
`29/467; 623/18; 623/23
`58) Field of Search ................. 29/419.1, 426.5, 469.5,
`29/429, 448, 439, 465, 466, 467; 72/401, 402;
`128/92 C, 92 CA; 623/11, 16, 18, 22, 23, 901,
`DIG. 1
`
`(60)
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`D. 283,731 5/1986 Kenna .................................. D24/33
`3,026,610 3/1962 Wakefield .....
`... 29/419.1
`3,605,123 9/1971 Hahn .....
`... 3/1
`3,808,606 5/1974 Tronzo .
`... 3/1
`3,855,638 12/1974 Pilliar .......................................... 3/1
`3,906,550 9/1975 Rostoker et al. .
`4,064,567 12/1977 Burstein et al. .
`4,276,765 7/1981 Yoneda ................................. 72/402
`4,406,023 9/1983 Harris................................... 3/1912
`4,479,271 10/1984 Bolesky et al. .
`4,495,664 1/1985 Blanquaert .
`4,536,894 8/1985 Galante et al. ....................... 62.3/22
`4,570,271 2/1986 Sump ..................................... 623/18
`4,589,883 5/1986 Kenna ................................... 623/22
`4,608,055 8/1986 Morrey et al. ........................ 623/23
`4,636,219 1/1987 Pratt et al. ............................ 623/22
`4,644,942 2/1987 Sump ..................................... 623/16
`4,660,755 4/1987 Farling et al. ...
`... 228/178
`4,718,916 1/1988 Morscher .............................. 623/23
`4,728,335 3/1988 Jurgutis ................................. 623/23
`
`
`
`4,752,296 6/1988 Buechel et al. ....................... 623/23
`4,778,475 iO/1988 Ranawat et al. ...................... 623/23
`4,828,566 5/1989 Griss ..................................... 623/23
`FOREIGN PATENT DOCUMENTS
`0178650 4/1986 European Pat. Off. .
`273871 7/1988 European Pat. Off. .
`2404214 8/1974 Fed. Rep. of Germany .
`1207495 9/1985 Italy.
`2059267 4/1981 United Kingdom.
`2142544 1/1985 United Kingdom .
`2142830 1/1985 United Kingdom.
`2153233 8/1985 United Kingdom.
`OTHER PUBLICATIONS
`Brown, University of Illinois-Chicago, Journal of Bone
`& Joint Surgery, "Correction of Poliomyelitic Deformi
`ties with Frothed Latex Prostheses', vol. 27, #5, 1945,
`pp. 513-517.
`Zimmer Brochure-"Collarles HGP Femoral Pros
`thesis'-1986.
`Howmedica Ad-"The PCA Total Hip System"-JBJS,
`Jun. 1984, 66-A.
`Osteonics Brochure-“Integrated Systems of Implants
`and Instrumentation'-1984.
`(List continued on next page.)
`Primary Examiner-Joseph M. Gorski
`Assistant Examiner-Peter Dungba Vo
`Attorney, Agent, or Firm-Margaret L. Geringer
`(57)
`ABSTRACT
`A method of constructing a prosthetic implant includ
`ing a porous pad separate from the stem of the implant
`and in which the pad is wrapped around the stem for
`attachment thereto. The pad is first precontoured into a
`preliminary shape and is then wrapped about the stem in
`a second and final shape corresponding to the shape of
`the stem portion about which it is wrapped and subse
`quently secured.
`
`-
`
`21 Claims, 6 Drawing Sheets
`
`ZIMMER EXHIBIT 1009
`
`Page 1 of 14
`
`

`

`5,018,285
`Page 2
`
`OTHER PUBLICATIONS
`Osteonics Brochure-“HS2P. Micro-Structured Hip
`System'-1984.
`S & G Implants Brochure-"Anatomical Hip Endopros
`thesis System-Lubeck'-No data available.
`Richards Ad-"Opti-Fix Porous Coated Hip System'-
`'-JBJS, Feb. 1987, 69-A.
`Techmedica Ad-"Customize, Don't Compromise'-
`
`'-JBJS, Jan. 1987, 69-A.
`Kirschner Ad-"Freedom of Choice: A New Dimension
`in Hip Arthroplasty'-JBJS, Jan. 1987, 69-A.
`DePuy Ad-"Exclusive . . . The AML Total Hip Sys
`tem'-JBJS, Jan. 1987, 69-A.
`Intermedics Orthopedics Brochure-"APR Universal
`Hip System"-1984.
`McDonnell Douglas Ad Illustrating a Techmedica
`Prosthesis-Industry Week, Apr. 1, 1985.
`
`Page 2 of 14
`
`

`

`U.S. Patent -
`U.S. Patent
`
`May 28, 1991
`May 28, 1991
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`Sheet 1 of 6
`Sheet 1 of 6
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`5,018,285
`5,018,285
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`US. Patent
`U.S. Patent
`
`May 28, 1991
`May 28, 1991
`
`V Sheet 2 of 6
`Sheet 2 of 6
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`5,018,285
`5,018,285
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` 74
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`F.G. 5
`FIG. 5
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`36
`36
`F. G. 6
`Fl 6. 6
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`26
`26'
`38
`38
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`Page 4 of 14
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`Page 4 of 14
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`US. Patent I
`U.S. Patent
`
`May 28, 1991
`May 28, 1991
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`Sheet 3 of 6
`Sheet 3 of 6
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`5,018,285
`5,018,285
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`Page 5 of 14
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`U.S. Patent
`US. Patent
`
`May 28,
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`5,018,285
`5,018,285
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`Page 6 of 14
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`US. Patent ,
`U.S. Patent
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`May 28, 1991
`May 28, 1991
`
`Sheet 5 of 6
`Sheet 5 of 6
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`5,018,285
`5,018,285
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`Page 7 of 14
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`U.S. Patent
`US. Patent
`
`May 28, 1991
`. May 28, 1991
`
`Sheet 6 of 6
`Sheet 6 of 6
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`5,018,285
`5,018,285
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`Page 8 of 14
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`1
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`5,018,285
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`METHOD OF CONSTRUCI'ING PROSTHETIC
`IIVIPLANT WITH WRAPPED POROUS SURFACE
`
`This application is a continuation of application Ser.
`No. 07/277,525 filed Nov. 28, 1988, which is a division
`of application Ser. No. 07/088,363 filed Aug. 24, 1987,_
`both now abandoned.
`
`BACKGROUND OF THE INVENTION
`
`The present invention relates to a prosthetic implant
`device and more particularly to such implants including
`porous surfaces thereon. This invention is particularly
`suitable for use as a femoral component for a hip pros-
`thesis, although is not limited thereto.
`Heretofore, various types of porous surfaces have
`been incorporated into prosthetic implants. Such po-
`rous implants are often implanted without the use of any
`type of bone cement material so that the porous surface
`will be in direct contact with the bone surface. After a
`period of time, bony ingrowth occurs in and around the
`porous surface to biologically affix or further secure the
`implant in the bone. Alternatively, an implant having a
`porous surface may be implanted with bone cement,
`such that the penetration of the bone cement into the
`porous surface of the prosthesis will enhance the fixa-
`tion of the prosthesis.
`The following US patents disclose prosthetic im-
`plants which include various types of porous surfaces:
`US. Pat. No. 3,906,550 to Rostoker et a1. discloses a
`porous fiber metal structure adapted for attachment to a
`prosthesis. The fiber metal material is molded directly
`into the desired precise shape using dies and punches.
`US. Pat. No. 4,479,271 to Bolesky et a1. discloses a
`prosthesis including porous surfaces which are also
`either molded and compressed directly into shape or
`compressed and out directly into shape.
`US. Pat. No. 4,536,894 to Galante et al. discloses a
`prosthesis including porous surfaces in which the po-
`rous surfaces are porous pads which are compressed
`and cut directly to the desired shape and then adhered
`to substantially flat surfaces.
`US. Pat. No. 4,570,271 to Sump discloses a prosthesis
`with a porous surface in which the porous coating is
`preformed directly into the desired shape which corre~
`sponds to the preselected surface of the prosthesis. The
`preform porous coating is then overlaid onto the prese-
`lected surface, compressed, and heated to adhere the
`preform to the prosthesis. The preform may be pro-
`duced by conventional multi-layer knitting, braiding,
`winding, weaving, or other continuous wire processes.
`US. Pat. No. 4,589,883 to Kenna discloses a prosthe-
`sis including a porous surface in which the porous coat-
`ing is comprised of spherical particles which appear to
`have been directly bonded to the prosthesis stern.
`U.S. Pat. No. 4,636,219 to Pratt et a1. discloses a
`prosthesis including a porous surface comprised of a
`layered metal mesh structure. The mesh may be bonded
`to a thin substrate (on the order of 0.010 to 0.012 inch)
`which thin substrate can then be cut or formed and
`applied to the body of a prosthesis on a flat surface as in
`FIG. 3 of Pratt et 211. or contoured into specific shapes
`by processes such as creep forming.
`US. Pat. No. 4,660,755 to Farling et a1. discloses a
`method for constructing a surgical implant in which a
`porous layer is bended to a substrate in the absence of a
`furnace, the bonding Occurring via an electrode.
`
`Page 9 of 14
`
`U.K. patent application No. GBZOS9267A to Du-
`cheyne discloses a type of porous metal wire mesh suit-
`able for use on a prosthesis.
`U.K. patent application No. GB2142830A to Brown
`et a1. discloses a prosthetic implant having a porous
`surface provided by a perforated micro-contoured
`sheet.
`
`U.K. patent application No. GB2153233A to Lee et
`al. disclose a prosthetic implant which utilizes wedges
`to wedge between the bone cavity wall and the prosthe-
`sis stem in which the wedges may include a porous
`surface.
`European patent application No. EP0178650A2 to
`Ducheyne discloses a porous flexible metal fiber mate-
`rial for implantation in conjunction with a prosthesis in
`which one or' more layers of the porous sheet material
`are pressed against the bone surface with a layer of bone
`cement then between the implant and the porous sheet
`material.
`
`OBJECTS AND SUMMARY OF THE
`INVENTION
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`A principle object of this invention is to provide a
`prosthetic implant which includes a porous pad separate
`from the prosthesis stem which is adapted for wrapping
`around the stem for attachment thereto.
`Another object of the invention is to provide a pros—
`thetic implant which includes a porous pad separate
`from the fixation surface base portion such that the
`porous pad has a first preliminary precontoured shape.
`The porous pad is adapted for wrapping about the fixa-
`tion surface base portion in a second and final shape
`corresponding to the shape of the fixation surface base
`portion about which it is wrapped.
`A further object of the invention is to provide such a
`prosthetic implant in which the pad is wrapped about at
`least two adjacent sides.
`Astill further object of the invention is to provide a
`process for wrapping a porous pad about a prosthesis
`stem in which the pad has a first preliminary, substan-
`tially flat precontoured shape which is subsequently
`wrapped about the stem into a second and final shape
`for attachment to the stem.
`The present invention accomplishes the above ob-
`jects and as such provides a prosthetic implant which
`includes a porous pad which is preliminarily formed
`into a first shape and then wrapped and/or formed
`about the stem of the implant to conform to the shape of
`the implant in a second and final shape. The pad is then
`adhered to the stem. The invention also provides a
`process for preparing the porous pad and for conve-
`: niently wrapping the pad about the stem.
`
`45
`
`50
`
`55
`
`65
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`These features and objects of the invention, as well as
`others, will become apparent to those skilled in the art
`by referring to the accompanying drawings:
`FIG. 1 is a perspective view of a femoral component
`for a hip prosthesis according to the present invention;
`FIG. 2 is an anterior side elevational view thereof;
`FIG. 3 is a lateral side elevational view thereof;
`FIG. 4 is a medial side elevational view thereof;
`FIG. Sis a cross-sectional view taken along lines 5—5
`of FIG. 2;
`FIG. 6 is a cross-sectional view taken along lines 6—6
`of FIG. 2;
`FIG. 7 is a side View of a femoral component accord-
`ing to the present invention located in a forming fixture
`
`Page 9 of 14
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`3
`with the fixture shown in a cross-sectional view taken
`along lines 7—7 of FIG. 8c;
`FIG. 8 is a cross-sectional view of the forming fixture
`taken along lines 8—8 of FIG. 7;
`FIGS. Sa,_8b, and 8c are cross-sectional views taken 5
`along lines 8—8 of FIG. 7 of the forming fixture illus-
`.
`trating various jaws in activated positions about the
`femoral component stem;
`FIG. 9 is a top view of a pressed and prebonded sheet
`of porous material;
`FIG. 10 is a top view of the sheet of FIG. 9 illustrat-
`ing a cut out portion;
`FIG. 11 is a top view of the porous pad formed from
`the cut out of FIG. 10;
`FIG. 12 is a side view of a femoral component ac- 15
`cording to the present invention located in a bonding
`fixture with the fixture shown in a cross-sectional view
`taken along lines 12—12 of FIG. 13;
`FIG. 13 is a cross-sectional view of the bonding fix-
`ture taken along lines 13—13 of FIG. 12;
`FIG. 14 is an anterior side elevational view of an
`alternate embodiment of a femoral component;
`FIG. 15 is posterior side view of the component of
`FIG. 14; and
`FIG. 16 is an alternate embodiment for a porous pad 25
`to be used in conjunction with the component of FIG.
`14.
`
`DETAILED DESCRIPTION OF THE
`
`30
`
`INVENTION
`FIGS. 1—13 illustrate a particularly advantageous
`embodiment of a prosthetic implant according to the
`present invention. The invention will be described with
`reference to a femoral component 10 of a hip prosthesis
`and is particularly suitable as such. However, it is un- 35
`derstood that the principles of the invention may be
`suitable for other implants having elongated fixation
`stems. In addition, it is noted for reference that the
`particular femoral component 10 described herein is
`designed for implantation in a right femur, while a cor- 40
`responding femoral component (not shown) for implan-
`tation in a left femur would be a mirror image of the
`femoral component 10 shown for the right femur.
`The femoral component 10 of FIGS. 1-6 includes a
`distal end 12 and a proximal end 14. As is well known, 45
`the femoral component 10 is intended to fit within the
`intramedullary canal of a femur (not shown) such that
`the proximal end extends outwardly from the intramed-
`ullary canal of the femur to cooperate with an acetabu—
`lum or acetabular prosthetic member via a ball or the 50
`like carried at the proximal end 14. A distal portion 16
`may include a plurality of grooves 18 extending longitu-
`dinally. A proxirhal portion 24 includes a porous surface
`or pad 26 encircling the femoral component 10. The
`distal portion 16 and the proximal portion 24 comprise 55
`the stern portion 20 of the femoral component 10. A
`neck 28 extends from the proximal portion 24 and is
`adapted to carry a ball 30 shown in phantom lines in
`FIG. 1. An aperture 31 adjacent the neck 28 accommo-
`dates a tool for removing the femoral component 10 60
`from the intramedullary canal should removal be neces-
`sary. The porous pad 26 is designed to extend out-
`wardly from the proximal portion 24 albeit a small ex-
`tension of about 0.5 mm past the adjacent smooth sur-
`face of the proximal portion 24.
`FIGS. 2, 3, and 4 illustrate a chamfer 32 on the ante-
`rior side of the femoral component which may be in-
`cluded to avoid impingement of the distal end 12 into
`
`65
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`Page 10 of14
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`4
`the bone surrounding the intramedullary canal at that
`location.
`As shown in FIGS. 1—4, the proximal portion 24
`includes a lateral side 34, a posterior side 36, a medial
`side 38, and an anterior side 40. 'A porous pad 26, as
`shown in the embodiment of FIGS. 1—6, is circumferen-
`tially wrapped around the proximal portion 24 of the
`stem portion 20. The'pad 26 may be formed of any
`suitable porous material that is adapted to be preliminar-
`ily pressed into a first shape and then subsequently
`wrapped about the stem portion 20 into a second shape -
`conforming to the shape of the stem portion 20. One
`such suitable material is the fiber metal structure dis-
`closed in US. Pat. No. 3,906,550 to Rostoker and Ga-
`lante, although it is noted that the Rostoker et a1. patent
`teaches that the fiber metal material is molded directly
`into the desired shape, rather than providing a first
`preliminary shape which is then subsequently wrapped
`or formed about a prosthetic implant into the second
`and final shape in accordance with the present inven-
`tion. It is understood that any suitable porous material,
`particularly fibrous (wire-type) porous structures which
`are adaptable to be practiced in accordance with the
`present invention, may be utilized. The material for the
`porous pad may be titanium wire having a diameter of
`0.010 inches, and the material for the femoral compo-
`nent may also be titanium. Again it is understood that
`any suitable materials may be utilized.
`The shape of the porous pad 26 may have any desir—
`able configuration, although preferably the pad is first
`formed in or pressed into a substantially flat sheet 126
`(see FIGS. 9—11). The outer boundary of the pad 26
`may have any suitable contour. The porous pad 26 is
`separate from the stem portion 20. The pad 26 is
`adapted for wrapping around the stem portion 20 for
`attachment thereto. The porous pad 26 has a first pre-
`liminary precontoured shape as shown in FIG. 11 and is -
`then subsequently wrapped and/or formed about the
`stem portion 20 for attachment thereto in a second and
`final shape corresponding to the shape of the stem por-
`tion 20 as shown in FIGS. 1—4. The porous pad 26 is
`wrapped around at least two to three adjacent sides,
`although preferably is wrapped around all four sides 34,
`36, 38, and 40 to form a continous porous surface cir-
`cumferentially about the stem portion 20.
`The porous material, such as a kinked titanium fiber
`metal, is press formed into a sheet 126 of porous mate-
`rial. The sheet 126 may have any desired thickness or
`dimensions. The dimensions of the sheet 126 may be
`adapted to cut out a single pad 26 having aldesired outer
`boundary or adapted to cut out multiple pads 26 from a
`single sheet. The sheet 126 is prebonded in a vacuum
`furnace by holding the sheet for a suitable length of time
`at a temperature sufficient to create metallurgical bonds
`at the points of contact of the fibers of the porous mate-
`rial within the sheet 126. A porous pad 26 having the
`desired outer contour is then cut from the sheet leaving
`a corresponding cut out 226 in the sheet 126. Prebond-
`ing the fiber metal sheet prior to cutting it creates me-
`chanical integrity in the sheet 126 so that the fiber mate-
`rial is more easily formable and holds its shape better.
`The porous pad 26, shown in FIG. 11 which is subse-
`quently applied to the femoral component 10 of FIGS.
`1—4, includes a medial pad side 138 to correspond to the
`medial stem side 38, posterior and anterior pad sides 136
`and 140 each extending from or adjacent to the medial
`pad side 138 and adapted to correspond to the posterior
`and anterior stem sides 36 and 40, respectively, and first
`
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`and second tabs 121 and 122 extending from the poste-
`rior and anterior sides, respectively. The two tabs to-
`gether comprise the lateral pad side 134 which will
`correspond to the lateral stern side 34 of the femoral
`component 10. The pad 26 may be asymmetric as shown
`with the posterior porous pad surface 136 having
`greater surface area than the anterior porous pad sur-
`face 140 and with the medial pad surface 138 being
`longer than the lateral pad surface 134. However, the
`pad 26 could readily be made symmetrically, if desired,
`as any appropriate shape may be utilized for'the pad 26.
`The pad 26 is then ready to be wrapped about the
`stem portion 20. The proximal portion 24 of the stem
`portiOn 20 includes a recess 74 (see FIG. 6) having a
`shape corresponding to the pad 26 and adapted to re-
`ceive the pad 26 for subsequent attachment thereto. The
`pads 26 can be shaped to conform to any desirable and
`suitable implant stem or fixation surface configuration.
`The proximal portion 24 of the stem portion 20 of the
`femoral component shown has an asymmetric noncircu-
`lar cross-section as shown in FIGS. 5 and 6.
`The process for wrapping the porous pad 26 may be
`accomplished by placing the femoral component 10
`(without pad 26)} in a forming fixture 60 as shown in
`FIGS. 7 and 8. The fixture 60 has a plurality of forming
`jaws 61, 62, 63, and 64. The forming jaws are each
`operated by corresponding rod 161, 162, 163, and 164,
`respectively, which operatively connects the jaws to
`cylinders 261, 262, 263, and 264, respectively. The cyl-
`inders 261, 262, 263, and 264 may be air operated cylin-
`ders or hydraulic cylinders or any other suitable activa-
`tion mechanism. The jaws, rods, and cylinders may be
`made of tool steel, or any other suitable material strong
`enough to form the porous pad 26 about the femoral
`component 10.
`The neck 28 of the femoral component 10 is seated in
`a cylindrical bushing 66 within base plate 68 of fixture
`60 to hold the femoral component 10 in place. A sliding
`locating pin 69 may be placed through the aperture 31
`to keep the femoral component 10 from rotating while
`the forming is taking place. The bushing 66 may suit-
`ably be made from a nonmetallic material such as delrin
`so as not to scratch the neck 28. The base plate may be
`made of aluminum or steel. Other suitable means of
`holding the femoral component 10 securely in the form-
`ing fixture 60 could also be utilized.
`The jaws 61, 62, 63, and 64 are each in a retracted
`position about the femoral component 10. The precut
`substantially flat porous pad 26 is placed in position
`between the jaws and the implant 10 with the medial
`pad portion 138 aligned with the corresponding medial
`side 38 of the stem portion 20. The jaws, which have
`interfacing surfaces corresponding to the desired pad
`and stem configuration, are then activated in a predeter-
`mined sequence to form the pad 26 about the implant
`conforming the pad 26 to the shape of the implant 10 as
`shown in FIGS. 80, 8b, and 8c. In FIG. 8a the first
`forming jaw 61 is activated from its retracted position to
`a position in which the first jaw 61 is pressed up against
`the medial porous pad surface 138 which is thus pressed
`against the corresponding medial ‘side 38 of the stem
`portion 20 shaping and locating the respective portion
`of the pad 26 thereto. The first jaw 61 is then held in its
`activated position against thestem portion 20.
`Alternatively,
`the medial porous pad surface 138
`could be preformed to the shape of the medial side 38 by
`utilizing a correspondingly shaped separate forming die
`(not shown) for just the medial side (rather than form-
`
`Page 11 of 14
`
`ing this medial side using the sequential fixture 60). The
`separate die would include a substantially U—shaped
`depression such as that shown in the cross-Section of
`jaw 61 in FIG. 80 and a corresponding U-shaped pro-
`jection corresponding to the outer contour of the me-
`dial side of the femoral component, which when
`brought together with the pad 26 in between would
`preform the pad 26 into the substantially U-shaped con-
`figuration, such as that achieved using the first jaw 61 of
`the sequential forming fixture 60. If such a separate die
`is used, the pad 26 having the preformed (U-shaped)
`medial pad surface 138 would then be placed in position
`in the forming fixture 60 between the jaws and the
`implant 10 with the preformed medial pad 138 aligned
`with the medial side 38 of the stern portion 20. The jaw
`61 would be activated to hold the pad 26 having the
`preformed medial pad surface against the stem portion
`20. The remaining sequential activation of the jaws
`would then continue.
`The second and third jaws 62 and 63 may be then
`activated simultaneously as shown in FIG. 8b to press
`the posterior and anterior porous pad surfaces 136 and
`140, respectively, against
`the posterior and anterior
`sides 36 and 40 of the stem portion 20 thus shaping the
`respective portions of the pad thereto. Jaws 61, 62, and
`63 are then held in this activated position against the
`stern portion 20.
`The fourth jaw 64 is then activated as shown in FIG.
`8c to press the first and second tabs 121 and 122 of the
`lateral porous pad surface 134 against the lateral side 34
`of the stem portion 20 thus shaping the respective por-
`tions of the pad thereto. The tabs 120 and 122 mate
`together on the lateral side 34 to form a flush interface
`27, thus providing a continuous circumferential porous ‘
`surface connecting the anterior, medial, posterior, and
`lateral sides.
`The forming jaws are then released from their acti-
`vated positions, and thus retracted away from the stem
`portion 20. The femoral component 10 with the con-
`formed pad 26 surrounding it is removed from the form-
`ing fixture 60. The femoral component 10 is then placed
`in an appropriate bonding fixture 80 such as in FIGS.
`12-13 in which the porous pad is held securely in place
`against the stem portion 20. The pad 26 is positioned
`securely in the recess 74 which corresponds to the
`wrapped shape of the pad 26. The porous pad 26 is then
`bonded to the stem portion 20 to securely attach it
`thereto. The bonding may be achieved by diffusion
`bonding the pad to the stem portion by holding the pad
`securely thereagainst at a sufficient temperature for a
`sufficient length of time to achieve secure bonding.
`However, it is understood that other bonding processes
`such as sintering or other suitable bonding methods may
`be utilized.
`
`Although any appropriate bonding fixture or holding
`mechanism may be used for bonding the pad 26 to the
`stem portion 20, FIGS. 12 and 13 illustrate such a suit-
`able fixture 80. The fixture 80 includes a support frame
`86 with a plurality of holding or bonding blocks or jaws
`81, 82, 83, and 84 which surround the porous pad 26 on
`the proximal portion 24 and which conform to the
`shape of the stem portion 20 about which they are posi-
`tioned. The bonding blocks which hold the, pad 26 in
`place against the stem portion 20 are suitably made of a
`carbon material, as is the frame 86. The bonding blooks
`81, 82, 83, and 84 are placed under sufficient pressure
`evenly holding the pad 26 against the stern portion 20
`via screws 88.
`
`5
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`10
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`15
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`5,018,285 .
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`8
`subsequently contacting with and applying force to
`the pad thereafter.
`2. The method of claim 1 further including the step of
`bonding the pad to the stem portion while holding the
`pad against the stem portion in a suitable bonding fix-
`ture.
`
`3. The method of claim 1 further including the steps
`of press forming and prebonding the porous pad prior to
`precontouring the pad.
`4 The method of claim 1 wherein the step of wrap-
`ping the pad around the stem portion further includes
`wrapping the pad around at least two adjacent sides of
`the stem portion.
`5. The method of claim 1 wherein the step of wrap-
`ping the pad around the stem portion further includes
`wrapping the-pad circumferentially around the plurality
`of sides substantially fully surrounding the stem portion.
`6. The method of claim 1 wherein the step of provid-
`ing a base implant further includes providing a base
`implant in which the stem portion has a noncircular
`cross-section and wherein the step of wrapping the pad
`further includes wrapping the pad around the stem
`portion in a second non-flat, noncylindrical configura-
`tion conforming to the shape of the stem portion about
`which the pad is wrapped.
`7. A method of constructing a prosthetic implant
`comprising the following steps:
`(a) providing a base metal implant including a stem
`portion having a medial, a posterior, an anterior,
`and a lateral side;
`(b) forming a sheet of porous fiber metal material;
`(c) prebonding the sheet to bond the fiber metal mate-
`rial together;
`(d) cutting a porous pad from the sheet to provide the
`pad with an outer boundary defining a desired
`contour and having a substantially flat first config-
`uration;
`(e) wrapping the pad around the stem portion for
`attachment thereto in a second non-flat configura-
`tion conforming to the shape of the stem portion
`about which the pad is wrapped; and
`(i) applying to said pad, thereby converting "said a
`plurality of sequentially applied forming jaws sub-
`stantially flat first configuration to the non-flat
`second configuration, said plurality of jaws apply-
`ing such force to the pad in a desired sequence,
`with one of 'said plurality of jaws initially contact-
`ing with and applying force to the pad first, and
`with at least one other of the plurality of jaws
`subsequently contacting with and applying force to
`the pad thereafter.
`8. The method of claim 7 wherein the step for wrap-
`ping the pad around the stern portion further includes
`the step of forming the pad conforming to the shape of
`one side of the stem portion first and then sequentially
`forming the pad corresponding to the shape of the re-
`maining sides.
`9. The method of claim 7 wherein the method further
`includes the steps of:
`(a) forming the pad corresponding to the shape of the
`stem portion to which it is to be attached by shap-
`ing the porous pad about a mandrel which has a
`shape which corresponds to the portion of the
`implant to which the pad is to be attached;
`(b) removing the formed pad from the mandrel,
`(c) placing the formed pad about the prosthetic im-
`plant; and
`(d) attaching the pad securely to the stem portion.
`
`-
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`7
`Alternatively, rather than forming the substantially
`flat first preliminarily shaped pad 26 about the stem
`portiOn 20 into its second and final contoured shape, the
`pad 26 can be formed about a mandrel (not shown)
`which has a shape which corresponds to the portion of 5
`the implant to which the pad is to be attached. This
`forming about a mandrel can be done with a fixture 60
`such as that described above used for forming the sub-
`stantially flat or medially preformed pad 26 about the
`implant itself. Then the formed pad 26 which has been
`shaped about the mandrel is removed from the mandrel
`and placed about the femoral component 10. The pad 26
`' can then be securely bonded to the stem portion 20 as
`described above.
`An alternate embodiment for a femoral component
`400 is shown in FIGS. 14—16 in which the porous pad
`426 is adapted to fit in recess 474. FIGS. 14 and 15 show
`the component 400 without the porous pad 426 there-
`about. The pad 426 is adapted to 'be wrapped about
`three adjacent sides including the lateral, medial, and
`anterior sides 36, 38, and 40 to form a continuous porous
`surface interconnecting these three sides. Since the pad
`426 does not completely surround all sides of the im-
`plant, the pad 426 may be conveniently formed from its
`substantially flat first preliminary shape (as shown in
`7 FIG. _16) to its second and final contoured shape which
`corresponds to the shape of the recess 474 in the stern
`portion 20 either by using a correspondingly shaped
`(substantially U-shaped for the embodiment shown in
`FIGS. 14—16) separate single forming die (not shown),
`or a forming fixture 60 with multiple sequentially oper-
`ated forming jaws such as previously described. The
`formed pad 426 can then be bonded to the stem portion
`20 in a similar manner as previously described for the
`pad 26 which circumferentially surrounds the stem
`portion.
`The prosthetic implant of the present invention pro-
`vides an implant having a wrapped porous pad and a
`method of wrapping such pad about a prosthetic stem
`portion. The present invention provides for a substan-
`tially flat pad having a predetermined outer boundary
`to be subsequently wrapped about a prosthesis stem to
`conform to the shape of the stem and to be attached
`thereto. While this invention has been described and
`exemplified in terms of particularly advantageous em-
`bodiments, those skilled in the art can appreciate that
`modifications can be made without departing from the
`spirit and scope of this invention.-
`_
`We claim:
`1. A method of constructing a prosthetic implant
`comprising the following steps:
`(a) providing a base implant including a stem portion
`having a plurality of sides;
`(b) precontouring a separate porous pad having a first
`desired configuration which is substantially flat;
`(c) wrapping the pad around the stem portion for
`attachment thereto in a second non-flat configura-
`tion conforming to the shape of the stem portion
`about which the pad is wrapped; and
`(d) applying a plurality of sequentially applied form-
`ing jaws to said pad, thereby convertingsaid sub-
`stantially flat first configuration to the non-flat
`second configuration, said plurality of jaws apply-
`ing such force to the pad in a desired sequence,
`with one of said plurality of jaws initially contact-
`ing with and applying force to the pad first, and
`with at least one other of the plurality of jaws
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`9
`10. The method of claim 7 wherein the step for wrap-
`ping the pad around the stem portion further includes
`the step of forming the pad corresponding to the shape
`of the stem portibn to which it is to be