_
`
`Umted States Patent [19]
`Slamin
`
`llllllllllllllllllllllIllllllllllllllllllllllllllllllllllIlllllllllllllllll
`[11] Patent Number:
`5,152,796
`[45] Date of Patent:
`Oct. 6, 1992
`
`USOO5l52796A
`
`[54] MODULAR KNEE PROSTHESIS
`
`[56]
`
`References Cited
`
`[75] Inventor: John E. Slamin, Wrentham, Mass.
`
`[73] Assignee: Johnson & Johnson Orthopaedics,
`Inc.’ Raynham, Mass.
`
`[21] Appl. No.: 713,921
`
`[22] Filed:
`
`Jun. 12, 1991
`
`[63]
`
`Related US. Application Data
`Continuation-impart of Ser. No. 630,419, Dec. 19,
`l990, abandoned, which is a continuation of Ser. No.
`560,247, M1 27, 1990, abandoned, which is a cominua.
`tion of Ser. No. 290,540, Dec. 27, 1988, abandoned.
`
`[51] Int. Cl.5 .............................................. .. A61F 2/38
`[52] U S Cl
`.
`........ .. 623/20
`[58] Field of Search ........................................ .. 623/20
`
`U'S' PATENT DOCUMENTS
`4,187,559 2/1980 Grell et al. .......................... .. 623/20
`623/20
`4’822’365 M1989 Walker 61 a1‘ '
`623/20
`4,822,366 4/1989 Bolesky ...... ..
`Primary Examiner-David Isabella
`Assistant Examiner-Debra S. Brittingham
`[57]
`ABSTRACT
`A knee prothesis system which is composed of a femo
`ral component and a series of bolts capable of being
`attached to the femoral component and extending
`thmugh the femmal °°mP9nem 3‘ different angles
`These angles correspond to dlfferent valgus angles The
`system also includes stems of different lengths and di
`ameters which can be attached to the bolts to provide a
`system with stems of different and diameter lengths set
`at different valgus angles.
`
`15 Claims, 3 Drawing Sheets
`
`22
`
`Smith & Nephew Ex. 1057
`IPR Petition - USP 8,377,129
`
`

`
`U.S. Patent
`US. Patent
`
`- Oct. 6, 1992
`- Oct. 6, 1992
`
`Sheet 1 of3
`Sheet 1 Ora
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`5,152,796
`5,152,796
`
`

`
`U.S. Patent
`U.S. Patent
`
`Oct. 6, 1992
`0a. 6, 1992
`
`Sheet 2 of 3
`Sheet 2 of 3
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`5,152,796
`5,152,796
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`22
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`

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`US. Patent
`
`Oct. 6, 1992
`
`Sheet 3 0f 3
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`5,152,796
`
`FIG 6
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`FIG
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`7
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`@EM?
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`IO
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`1
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`5,152,796
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`2
`provide for a prosthesis with no stem or variation in the
`valgus angle of the stem.
`US. Pat. No. 4,822,366 discloses a modular knee
`prosthesis in which the valgus angle of a femoral stem
`including a femoral stem extension can be varied to
`some degree. The con?guration of the device requires
`extensive removal of bone from the distal femur to
`implant the device.
`
`SUMMARY OF THE INVENTION
`The prosthesis of the present invention gives a ?exi
`bility to the orthopedic surgeon in providing a single
`femoral component of a total knee prosthesis. This fem
`oral component is identical for right or left knees and
`can be varied to accept stems of different diameters,
`different lengths and set at different valgus angles for
`use in right or left knees. The system of the present
`invention allows a surgeon greater ?exibility in the
`implantation of a prosthesis and provides a number of
`relatively inexpensive components to be available and
`ready to be implanted during the surgical procedure.
`The system of the present invention is particularly use
`ful for revision knee surgery. This prosthesis simpli?es
`inventory control systems and the cost of inventory for
`both the manufacturer and hospital and therefore re
`duces the costs of such procedures.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`In the drawings:
`FIG. 1 is an isometric view of the completely assem
`bled prosthesis of the present invention.
`FIG. 2 is a front view showing the prosthesis of the
`present invention.
`FIG. 3 is a side view, partially in section, of the pros
`thesis of the present invention.
`FIG. 4 is an exploded view of a portion of the pros
`thesis of the present invention.
`FIG. 5 is an exploded view of the prosthesis of the
`present invention.
`FIG. 6 and FIG. 7 are side views, partially in section,
`of embodiments of the invention in which there is a
`variation in the diameter of the stem.
`
`MODULAR KNEE PROSTHESIS
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`This application is a continuation-in-part of applica
`tion Ser. No. 630,419 ?led Dec. 19. 1990 ABN, in turn
`is a continuation of application Ser. No. 560,247 ?led
`Jul. 27, 1990, now abandoned, which in turn is a contin
`uation of application Ser. No. 290,540 ?led Dec. 27,
`1988, now abandoned.
`
`BACKGROUND OF THE INVENTION
`1. Field of the Invention
`The present invention relates to a modular knee pros
`thesis system, that is a system of implantable prosthesis
`used to replace a natural knee and which includes a
`series of intramedullary stems having different con?gu
`rations including different lengths and different valgus
`angles. The valgus angle and the stem length and stem
`diameter can be varied by the surgeon immediately
`prior to the implantation of the device which allows
`greater surgical ?exibility in the implantation of a total
`knee prosthesis.
`‘
`2. Prior Art
`Total knee prostheses have been in use for some time.
`These prostheses generally comprise a tibia component,
`a femoral component and a patellar component. The
`femoral component of the prosthesis generally com
`prises spaced-apart condylar portions and a connector
`joining the condylar portions. The tibial component of
`the prosthesis is constructed to receive the condylar
`portions of the femoral component, that is, the condylar
`portions are in direct contact and are supported by the
`tibial component. The femoral contact surface of the
`tibial component is made from a biocompatible plastic
`material such as ultra high molecular weight polyethyl
`ene. The patellar portion of the prosthesis is generally a
`ultra-high molecular weight polyethylene button,
`which may be metal backed or reinforced, and which is
`af?xed to the natural patella and rides in a depression on
`the metal surface of the femoral component. Typical of
`such prosthesis is the prosthesis shown in US. Pat. No.
`
`15
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`25
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`35
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`4,298,992.
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`-
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`'
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`45
`
`The prostheses of the type shown in the above men
`tioned patent are generally available with or without an
`intramedullary stem. The intramedullary stem is used to
`lend lateral stability to the prosthesis and is inserted into
`the medullary canal of the femur. The stems are set at an
`angle to the vertical which duplicates the valgus angle
`in the human anatomy. The valgus angle is the angle
`between the center line of the femur and an imaginary
`vertical line extending from the distal femur to the cen
`ter of the femoral head. This angle is generally some
`where between 5° and 9”.
`When selecting a prosthesis for implantation, the
`surgeon does not necessarily know the valgus angle
`precisely and may or may not know whether or not a
`prosthesis with an intramedullary stem would be de
`sired for the particular patient. It is the general rule of
`thumb that the least complicated prosthesis which re
`quires the least removal of bone from the patient would
`be the prosthesis of choice to be implanted.
`Modular prosthesis such as those shown in US. Pat.
`Nos. 4,404,691 and 4,578,081 have been proposed. The
`prosthesis disclosed in these patents have stems or
`shanks which may be extended in length, but do not
`
`55
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`65
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`DETAILED DESCRIPTION OF THE
`INVENTION
`As shown in FIGS. 1-3, the prosthesis of the present
`invention consists of a femoral component which has
`two condylar surfaces 10 which are joined by intercon
`dylar connector 11. The condylar surfaces have a pa
`tella depression 12 between the condylar surfaces which
`allows for the patellar portion of the total knee prosthe
`sis to ride in the depression 12 when the knee is ?exed.
`For purposes of orientation, the inner surface 25 of the
`prosthesis is referred to as the inferior surface and the
`outer surface 26 is referred to as the superior surface.
`The side of the prosthesis having the patella depression
`12 is the anterior side of the prosthesis and the opposite
`side is the posterior side. The portion of the prosthesis
`including the condylar surfaces and the intercondylar
`connector may be similar in construction to the prosthe
`sis that is shown in U.S. Pat. No. 4,298,992. In the pres
`ent prosthesis, there is an aperture 13 which is shown in
`the drawings as being a circular aperture. This aperture
`could be a different shape if desired. At the posterior
`edge of the aperture there is a small opening or slot 16
`whose purpose will be subsequently described. The
`present prosthesis includes a femoral bolt 17 which has
`the same cross sectional con?guration as the aperture
`
`

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`15
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`25
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`30
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`5,152,796
`3
`4
`and which will ?t through the aperture and extend
`6, the ratio of the diameter of the proximal portion
`through a stem collar 18 and into the threaded portion
`(larger diameter) to the distal portion (smaller diameter)
`of a stem 19. The interior of the stem has a female por
`may be from about 1 to l to about 2 to 1, preferably
`tion of threads which can be threaded onto the threaded
`about 1.3 to l. The stem shown in FIG. 7 has a distal
`portion of the femoral bolt 17 when the device is assem
`end 30 which is the same diameter as the stem collar 18.
`bled. The bolt will be held in position in the aperture as
`The proximal end 31 of the stern has diameter which is
`the head 14 of the bolt is wider than the aperture 13.
`smaller than the diameter of the distal portion of the
`When the stem on the bolt is tightened, the stem collar
`stem. The ratio of the diameter of the distal (larger
`18 and the bolt head 14 are drawn toward each other
`diameter) portion to the diameter of the proximal
`until the bolt head 14 and stem collar 18 are in ?rm
`(smaller diameter) portion may be from about 1 to 1 to
`contact with the intercondylar surface thereby holding
`2 to 1, preferably about 1.3 to 1. A ratio of 1 to l indi
`the stem at the proper valgus angle. The stem collar has
`cates that the stem has a constant diameter along its
`a circumferential slot 21 near the end of the collar
`length. The distal portion of the stems could be the same
`which can receive a circular clip 22 to lock the stem
`diameter as the stem collars used with the constant
`onto the stem collar. There is a corresponding depres
`diameter stems, i.e. 10 or 13 millimeters. The proximal
`sion or slot 23 in the stem. As shown in FIG. 4, the clip
`portions of the stems would be 10 or 22 millimeters.
`22 ?ts partially into the slot 21 in the stem collar and
`Other than the variation in the diameter of the stem, the
`' partially into the slot 23 in the stem to lock the stem
`details of the construction of the embodiments of the
`onto the stem collar. The femoral bolt has a head 14
`stems of FIG. 6 and FIG. 7 is the same as that shown in
`which is sized to snugly ?t into a recess 15 on the supe
`FIG. 4 and FIG. 5.
`rior surface of the intercondylar connector.
`It should be understood that the basic femoral com
`The femoral bolt 17 is constructed with the axis of its
`ponent design in the present system can be used for
`shaft at an angle to the head 14 of the bolt which can be
`either the right or left knee whether or not a stem is
`seen in FIG. 2. The head of the bolt is also angled so
`used. If the stem is used, it is necessary to have bolts that
`that the surface of the head is relatively flush in the
`are inclined to the left or right depending on which
`recess 15 in the bottom of the intercondylar box. The
`knee would be involved. The bolts would also have
`stem forms an angle ,the valgus angle, with the bottom
`different valgus angles. If one wanted to have the capa
`of the box of from 5°, 7° or 9°. These are the angles that
`bility of implanting a prosthesis in either the right or left
`are generally used in stem prosthesis constructions for
`knee at valgus angles of 5°, 7° or 9° and with stem diam
`the valgus angles. The bolt, when it is fully seated in the
`eters of 13 or 15 millimeters and stem lengths of 90 or
`bottom of the intercondylar box, forms the valgus an
`130 millimeters, it would normally be necessary to have
`gle. The stem collar,in order to ?t tightly around the
`available twelve different prosthesis for the right knee
`bolt, has an angle with the horizontal which corre
`and twelve different prosthesis for the left knee. In the
`sponds to the valgus angle.
`present modular system, one would need only a single
`In the modular system of the present invention, bolts
`femoral component, and would preferably have 12 left
`are provided in right and left con?gurations and at
`knee stem sets and 12 right knee stem sets available for
`angles of 5°, 7° and 9°. For each bolt, there is a corre
`implantation. Since the actual femoral component is the
`sponding stem collar. The stems are provided in con
`most expensive component, it is not necessary to keep a
`stant but different diameters, usually 13 millimeters and
`high cost inventory of this component, but a great num
`15 millimeters and of different lengths such as 90 and
`ber of implant options can be made with the changing of
`the relatively inexpensive materials such as the femoral
`130 millimeters. The stem collars are sized to corre
`spond to the diameter of the stem. For each knee, i.e.,
`bolt, the intramedullary stems and the stem collars.
`right or left, there are 12 possible modi?cations; three
`With the use of stems of variable diameter, even more
`different valgus angles each having two possible stem
`options are available to the surgeon. If the prosthesis of
`diameters and two possible stem lengths.
`the present invention were selected by an orthopedic
`FIG. 6 and 7 show alternate embodiments of the
`surgeon for implantation, the surgeon would have avail
`present invention in which there is a variation in the
`able the correct size of the femoral component and a set
`diameter of the stem along its length. The distal portion
`of femoral bolts, stems and stem collars. If, during the
`of the stem 18 is that portion which is in contact with
`operative procedure it would appear that a stem would
`the stern collar and extends proximally a distance which
`not be needed for the particular patient, the stem, femo
`50
`is about equal to the length of the femoral bolt 17. The
`ral bolt, stem collar would not be used. If it was decided
`proximal portion is the remainder of the stem. The
`that a stem would be used, the correct valgus angle
`purpose of variable diameter stems is to provide stems
`femoral bolt and stem assembly of the desired diameter
`in which the diameter of the proximal portion may be to
`and length would be selected. The femoral bolt would
`varied to more closely correspond to the diameter of 55
`then be ?tted into the bottom of the femoral component
`the medullary canal of the femur of a particular patient.
`and the stem assembly inserted with the antirotation
`The diameter of the distal end of a particular stem is
`stud 20 of the stem collar in the slot 16. The antirotation
`sized to correspond to the diameter of a particular stern
`stud 20 sitting in the slot 16 would prevent the rotation
`collar. Therefore, stems which have a constant diameter
`of the stem collar when the stem is tightened on the
`and stems with proximal portions having diameters
`femoral bolt. After the stem was tightened to the bolt,
`larger or smaller than the diameter of the collar can be
`the prosthesis would be ready to implant.
`?tted to the same stem collar. This offers surgeons
`The stems and stem collars can be preassembled at a
`greater ?exibility in construction of a prosthesis to ?t
`factory into a stem assembly if desired. Each stem as
`the needs of a particular patient. The stem shown in
`sembly would include a stem and a stem collar of the
`FIG. 6 has a distal end 28 which is the same diameter as
`same diameter as the stem, connected with a circular
`the stem collar 18. The proximal portion of the stem 29
`clip. The preassembly of the stem and stem collars is a
`has a diameter which is larger than the diameter of the
`convenience to the surgeon. During the surgical proce
`distal portion of the stem 28. In the stem shown in FIG.
`dure, if the surgeon would decide that a stern were to be
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`5,152,796
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`desirable, he would select the proper bolt and stem
`assembly, insert the bolt through the aperture 13 and
`attach the stem assembly to the bolt insuring that the
`stud 20 is positioned in the slot 16.
`I claim:
`1. A modular femoral component for a modular knee
`system, comprising a femoral component with two
`condylar surfaces joined by an intercondylar connector
`having an inferior portion and including at least two
`femoral bolts having a shaft and head, at least one of
`said bolts constructed with said shaft at an acute angle
`to said head, each of said bolts adapted to be connected
`to and ?tted into an opening in said intercondylar con
`nector, a recess in a superior surface of the opening, the
`head of the bolt being shaped so that the head is ?ush in
`the recess when the bolt is seated therein and the bolt
`extending upwardly towards an inferior surface of the
`femoral component, at least one stem collar adapted to
`be ?tted around the bolt and in contact with the inferior
`portion of the intercondylar connector, the stem collar
`and the femoral bolt being ?xable into the intercondylar
`connector at acute angles which correspond to a valgus
`angle desired in the implanted femoral component, and
`in which a plane passing along a surface of the stem
`collar in contact with the inferior portion of the inter
`condylar connector forms an acute angle with a plane
`passing along an opposite surface of the stem collar
`which corresponds to the valgus angle, a series of at
`least two stems of different lengths, the distal portion of
`each of said stems having an equal diameter as its associ
`ated stem collar and each of said stems being adapted to
`be ?xed to a femoral bolt to form a completed femoral
`component.
`2. The femoral component of claim 1 in which at least
`one of the bolts is angled to the left of the opening in the
`intercondylar connection and at least one of the bolts is
`angled to the right of the opening in the intercondylar
`connector.
`3. The femoral component of claim 1 in which the
`series of stems includes at least four stems and proximal
`portions of said stems having at least two different di
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`20
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`6
`intercondylar connector, at an angle which differs from
`the angle at which the other bolts extend when fully
`seated in the intercondylar connector.
`5. The femoral component of claim 4 wherein the
`proximal portion of said stems are of at least two differ
`ent diameters.
`6. The femoral component of claim Sin which at least
`one of said bolts is angled to the left of the opening in
`the intercondylar connector and at least one of said
`bolts is angled to the right of the opening in the inter
`condylar connection.
`7. The femoral component of claim 1 in which each
`stem further includes, a connector to connect the stem
`collar to the stem and in which each stem collar is sub
`stantially cylindrical.
`8. The femoral component of claim 7 in which the
`stem is threaded onto the femoral bolt to af?x the stem
`in position.
`9. The femoral component of claim 7 in which the
`femoral bolt extends from the superior surface of the
`femoral component through a aperture, said aperture
`having a slot at a posterior edge and said stern collar
`having a stud on its lower surface which fits into said
`slot to prevent rotation of the stem collar.
`10. The femoral component of claim 1 in which the
`ratio of the diameter of the distal portion of the stem to
`the proximal portion of the stem is from 2 to l to l to l.
`11. The femoral component of claim 1 in which the
`ratio of the diameter of the proximal portion of the stem
`to the distal portion of the stem is from 2 to l to l to l.
`12. The femoral component of claim 1 in which the
`proximal portion of the stem has the same diameter as
`the distal portion of the stem.
`13. The femoral component of claim 1 in which the
`proximal portion of a stem has a different diameter than
`the distal portion of the stem.
`14. The femoral component of claim 13 in which the
`diameter changes of the distal portion of the stem is
`larger than the diameter of the proximal portion of the
`stem.
`15. The femoral component of claim 13 in which the
`diameter of the proximal portion of the stem is larger
`than the diameter of the distal portion of the stem.
`ll
`ll
`1!
`t t
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`40
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`ameters.
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`.
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`4. The femoral component of claim 1 having at least
`three femoral bolts, each of said bolts having different
`acute angles thereby extending, when fully seated in the
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