CA2153913A1 - Anti-rotation implant prothesis - Google Patents

Abstract

An endoprosthetic apparatus which may be utilized with an associated guide apparatus that guides the formation of a hole in a bone through which is insertable a fastener to prevent rotation of the implanted endoprosthetic apparatus relative to the bone.
The endoprosthetic apparatus includes an attachment member, with a fastener receiving bore, and a first guide locating module.
When the attachment member inserts into a bone hollow, the bore is hidden within the bone but the locating module remains exposed. The guide apparatus includes a cooperating locating module shaped to engage the first guide locating module, and when so engaged a guide bore of the guide apparatus is aligned with the attachment member bore. The guide bore is then used as a guide for a drill utilized to form a hole in the bone through which a fastener inserts into the attachment member bore. The endoprosthetic apparatus may include an artificial knuckle and an attachment member which is attachable to the exterior of a bone.

Description

2~53913 ~._ Dr. Benny Fair ANTI-ROTATION IMPLANT PROSTHESIS
BACKGROUND OF THE INVENTION
This invention pertains to an endoprosthetic apparatus, and, in particular, to an endoprosthetic joint secured during implantation to resist rotation during subsequent usage.
A variety of endoprosthetic apparatuses are known which are employed to replace different defective or deteriorating internal portions of a human body. The digits of the hands and feet are - frequently the subject of the implantation of such apparatuses.In particular, due to a number of causes such as rheumatoid arthritis or a deforming injury or congenital condition, the joints between the metacarpal bones and phalanges in the fingers, or the metatarsal bones and phalanges of the toes, may require replacement with an endoprosthetic joint. A number of endoprosthetic joints potentially implantable in the hands or feet of a patient are known, and include devices disclosed in U.S. Patent Nos. 4,911,719, 4,194,250, 4,193,139, 4,131,957, 4,059,854, and 3,899,796.
One shortcoming of many existing endoprosthetic joints pertains to a tendency to become misaligned during subsequent use. For example, endoprosthetic joints for digits typically involve hinged opposing stems which are each inserted into the hollow core of a bone after the bone marrow has been surgically extracted. Bone cement injected into these cores is used to secure the stems in the cores at a rotational orientation of the stems which the implanting surgeon selects to provide a life-like joint operation. Regardless of the stems configurations, --- frequently over time the bone cement presently being utilizedbegins to wear or break down around the stems. Consequently, the stems can begin to rotate or longitudinally piston within the bones, causing the toe or finger digit to experience similar 21~3913 motion which appears unnatural. As a result, the realistic appearance and motion of the digits may be compromised.
Thus, it desirable to provide an endoprosthetic apparatus which over time will not experience movement relative to the bones to which it may be attached in order to maintain during usage, the lifelike appearance of the body portion which the apparatus has replaced.
SUMMARY OF THE INVENTION
The present invention is a prosthetic device which is surgically implanted. In one form thereof, the present invention provides an endoprosthetic apparatus and an associated guide apparatus. The endoprosthetic apparatus includes a first attachment member, a first guide locating module, a fastener, and a second attachment member. The first attachment member is insertab'e into a hollow of a first bone and includes a bore which resides within the first bone hollow when the first attachment member is inserted therein. The first guide locating module is positioned in spaced relationship with the bore such that the guide locating module resides outside the first bone hollow when the first attachment member is inserted into the first bone hollow. The second attachment member is operatively connected to the first attachment member and is attachable to a second bone. The guide apparatus includes a body with a guide bore for guiding formation of a hole in the first bone through which the fastener inserts. The guide apparatus also includes a cooperating locating module shaped complementarily to the first guide locating module for engagement therebetween to allow operative arrangement of the guide apparatus body relative to the first attachment member for hole formation. The body guide bore is located along the body at a predetermined position such that the body guide bore and the first attachment member bore are aligned when the cooperating locating module and the first guide 21~3~13 locating module engage to operatively arrange the guide apparatus body and the first attachment member.
In another form thereof, the present invention provides an endoprosthetic joint including a first attachment member, an articulated joint, and a second attachment member. The first attachment member is attachable to a first bone and includes at least one arm, which is positionable adjacent to the exterior of the first bone and has multiple fastener receiving apertures.
The articulated joint is operatively connected to both the first and second attachment members. The second attachment member is attachable to a second bone.
In still another form thereof, the present invention provides an endoprosthetic joint including a first attachment member attachable to a first bone, a second attachment member attachable to a second bone, an articulated joint operatively connecting the first and second attachment members, and an artificial knuckle. At least one of the first and second attachment members includes a first type attachment module. The artificial knuckle is structured to at least partially encapsulate the articulated joint and includes a second type attachment module shaped complementarily to the first type attachment module for engagement therewith. Either the first type attachment module or the second type attachment module includes a projection, and the other of the first type attachment module and the second type attachment module includes a projection receiving cavity.
One advantage of the present invention is that future undesirable rotation of the implant relative to the bone to which the implant is surgically attached is prevented. Another advantage of the present invention is that the location of a fastener receiving bore in an implant can be identified despite the bore being hidden by a surrounding bone. Still another 21.~39~3 advantage of the present invention is that it provides a realistic knuckle which fills the space between the hinged bones.
BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned and other advantages and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Fig. 1 shows a perspective view of a preferred embodiment of an endoprosthetic apparatus and associated guide apparatus of the present invention;
Fig. 2 shows an abstract side view of the endoprosthetic apparatus of Fig. 1 after its implantation replacing a joint between the bones of a patient;
Fig. 3 shows a cross-sectional top view, taken along line 3-3 of Fig. 2, of the implanted endoprosthetic apparatus;
Fig. 4 shows an exploded top view of the endoprosthetic apparatus, initially inserted into opposing bones of a patient, the associated guide apparatus, and an introduced drill employed to drill a fastener receiving bore through the bone of a patient;
Figs. 5 and 6 show partial side views of the endoprosthetic apparatus showing alternative shapes for the projection receiving cavity of the guide locating module;
Fig. 7 shows a perspective view of an alternate embodiment of the endoprosthetic apparatus of the present invention;
Fig. 8 shows a perspective view of the endoprosthetic apparatus of Fig. 1 with an artificial knuckle attached thereto;
Fig. 9 shows a cross-sectional view, taken along line 9-3 of Fig. 8, of the endoprosthetic apparatus with the attached --~ artificial knuckle;

21.~39~3 Fig. 10 shows a top view of the endoprosthetic apparatus of Fig. 1 with a multiple-piece artificial knuckle;
Fig. 11 shows a partial, cross-sectional view of a projection with locking tabs by which the artificial knuckle may be attached to a cavity having locking notches in the endoprosthetic apparatus;
Fig. 12 shows an elevational side view of an alternate embodiment of an endoprosthetic joint; and Fig. 13 shows a top plan view of the endoprosthetic joint of Fig. 12.
Fig. 14 shows a sectional view of the endoprosthetic joint of Fig. 13 after being shifted to an angled orientation, taken along line 14-14 and viewed in the direction of the arrows.
Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to Fig. 1, a preferred embodiment of an endoprosthetic apparatus of the present invention, generally designated 15, and a preferred embodiment of an associated guide apparatus of the present invention, generally designated 50, are shown in disassembled arrangement. Endoprosthetic apparatus 15 is illustrated and further described herein as being an endoprosthetic articulated joint particularly suitable for implantation between bones located in the digits of a hand or foot of a patient. However, it will become apparent in view of the following disclosure that the teachings of the present invention may also find advantageous application with other types of endoprosthetic apparatuses, wherein the attachment of these -- apparatuses to bones with mechanical fasteners is desirable, and 21~ 3 913 therefore the invention claims are intended to encompass apparatuses other than the shown articulated joint.
_ Referring to Figs. 1 and 2, endoprosthetic articulated --- joint 15 includes a first stem 17 and an opposing second stem 19.
The different sizes of stems 17, 19 are a function of their intended usage, such as to serve as attachment members to the proximal phalange and the middle phalange of a patient's finger.
Stems 17, 19 are operatively connected in this embodiment by an articulated joint or hinge 20, which allows for pivotal movement of stem 17 relative to stem 19. Elongated in a longitudinal direction, stems 17 and 19 both include generally rectangular transverse cross-sections which taper in size away from hinge 20.
Stems 17, 19 can also be alternatively shaped and sized so as to have, for example, a generally circular cross-section. While shown being of a unitary construction, first stem 17, second stem 19, and articulated joint 20 may be separately formed and then interconnected for use. Endoprosthetic joint 15 may be fabricated from appropriate non-reactive materials, such as various plastics or titanium, suitable for internal use in a body.
Formed along a middle portion of the longitudinal length of first stem 17 and second stem 19 and completely extending therethrough are transverse bores 22, 23. As shown in Fig. 2, when first stem 17 and second stem 19 are inserted into hollows reamed or bored into opposing bones 46 and 47 in preparation for the implantation of endoprosthetic joint 15, transverse bores 22, 23 reside within the bone hollows.
--- As shown in Fig. 2, body segments 24, 25 are the portions of endoprosthetic joint 15 between first stem 17 and hinge 20 and second stem 19 and hinge 20 respectively which protrude into the open region between bones 46, 47 when stems 17, 19 are fully inserted into the bones during prosthesis implantation. 8Ody 21;~3913 segments 24, 25 can also be considered portions of the inward ends of the respective stems 17, 19 which are exposed after - complete stem insertion. Guide locating module 27 is preferably formed within apparatus body segment 24, and guide locating module 28 is preferably formed within apparatus body segment 25.
Module 27, which engages guide apparatus 50 during the implantation procedure as described more fully below, is preferably a projection receiving cavity which transversely extends into body segment 24. As better shown in Fig. 5, projection receiving cavity 27 is square in cross-sectional shape and defines a parallelepiped volume. Provided corresponding changes are made in projection 55 of guide apparatus 50, alternate cavity constructions are possible. For example, the hexagonal configuration of module 27' shown in the partial side view of Fig. 6, as well as additional distinct cross-sectional shapes such as a star or other polygons, may be used. Guide locating module 27 may be formed on any surface of first or second stem bur preferably on the same side as transverse bores 22, 23.
Guide locating module 27 is positioned along the longitudinal length and height of body segment 24 in a particular spaced relationship with transverse bore 22. This positioning is a function of the configuration of a guide bore and a cooperating locating module of guide apparatus 50. Guide locating module 28 is preferably positioned with respect to transverse bore 23 in a similar spaced relationship, such that a single guide apparatus 50 can be utilized to provide both fastener receiving bores used in the mechanical fastening of stems 17, 19 to bones 46, 47.
When formed as cavities, guide locating modules 27, 28 may be a continuous bore extending through the entire width of body segments 24, 25. Alternatively, as represented in Fig. 3, guide 21~3~I3 locating modules 27j 28 can each be a pair of bores formed at identical locations along either side of body segments 24, 25.
Placing modules 27, 28 on both sides of endoprosthetic joint 15 allows a surgeon to drill from whichever side is more convenient, as well as allows a more secure attachment of artificial knuckles as described further below. It will also be appreciated that with corresponding changes to guide apparatus 50, guide locating modules 27, 28 could be protuberance or projections designed to mate with recesses in guide apparatus 50.
As shown in Fig. 3, transverse bores 22, 23 can receive various types of fasteners capable of securing and maintaining endoprosthetic joint 15 in its implanted orientation. In Fig. 3, a screw type fastener 41 is shown inserted through a hole formed in bone 47 and extending fully through transverse bore 23. An alternate fastener, namely pin type fastener 42, is shown passing through a hole formed in bone 46, extending through transverse bore 22, and ending back within a portion of bone 46 adjacent the bone interior hollow. Pin 42 can be, for example, a roll type pin which radially expands after its insertion. Other types of fasteners known in the art may be utilized to secure endoprosthetic joint 15 in its implanted orientation, and may include a bolt, having a threaded distal end, which extends from a first side of bone 46 and engages a threaded nut provided on the opposite side of bone 46.
Referring again to Fig. 1, guide apparatus 50 is shown including a generally elliptical body 52 which is provided with a transverse bore 5~ extending completely through the body thickness proximate one body end. Connected proximate the other end of body 52 and projecting laterally therefrom is a cooperating locating module 55, which is shaped complimentarily to guide locating module 27. Consequently, for the shown embodiment, module 55 is a projection having a square cros6-215391~

sectional shape. Projection 55 is configured relative to body 52 such that when projection 55 inserts and thereby engages guide locating module 27, guide body 52 is operatively arranged parallel to and along the longitudinal length of first stem 17 such that body bore 54 is aligned with stem transverse bore 22.
It will be appreciated that the distinct shapes of modules 27, 28 ensure that proper bore alignment occurs, as stem transverse bore 22 will be hidden within bone 46 during implantation. When guide apparatus 50 is removed from recess 27 and rotated 180 degrees from the orientation shown in Fig. 1, and projection 55 inserts into guide locating module 28, body bore 54 of operatively arranged guide body 52 will be aligned with transverse bore 23 of second stem 19.
With reference to Fig. 4, the implantation of endoprosthetic joint 15 will now be more particularly explained. After the bone marrow has been reamed out or removed to thereby form a hollow in each bone, joint stems 17, 19 are longitudinally inserted into position within the hollows of bones 46, 47 respectively.
Stems 17, 19 are inserted to such an extent that the portions of apparatus body segments 24, 25 which house guide locating modules 27, 28 project into the joint space between the bones.
At this stage of the procedure, bones 46, 47 and endoprosthetic joint 15 appear as diagrammatically shown in the cross-sectional view of Fig. 4. Guide apparatus 50 can then be operatively arranged with respect to either stem 17, 19, and is shown in Fig. 4 being arranged with stem 19 by way of the engagement of module projection 55 with projection receiving cavity 28. While rotating endoprosthetic apparatus 15 relative to the bones, a surgeon flexes the digit of the patient along hinge 20 to ~-~ 30 determine how the digit and endoprosthetic apparatus 15 must be aligned to achieve appropriate motion. When the resulting digit motion is satisfactorily lifelike, a K-wire drill 48 known in the 2153~

art may be used to provide a hole through bone 47 through which a fastener can be inserted. In particular, K-wire 48 inserts through guide apparatus bore 54 and into cutting engagement with the portion of bone 47 aligned with transverse bore 23. After cutting is complete and K-wire drill 48 and guide apparatus 50 are removed, fastener 41 tsee Fig. 3) may be screwed into the drilled hole in bone 46 and transverse bore 23 to thereby fixedly secure endoprosthetic joint 15 to the bone in a manner which resists relative rotation therebetween. It will be appreciated that guide apparatus 50 can then be used in conjunction with transve~se bore 22 and guide locating module 27 associated with first stem 17 to thereby attach endoprosthetic joint 15 in a similar fashion to bone 46 to complete the implantation procedure.
The provision of transverse bores 22, 23 is advantageous in that a surgeon is not required to drill or bore out the stem region which may introduce foreign particulates to the operating zone, as well as because it reduces the amount of time drill 48 is operated.
Referring now to Fig. 7, there is shown a perspective view of an alternate embodiment of the endopro~thetic joint 15' of the present invention. In this embodiment, stem 19 is shaped and configured identical to its corresponding element in the embodiment of Fig. 1, and therefore stem 19 includes transverse bore 23 and guide locating module 27 formed within body segment 25. Articulated joint 20 is also utilized in this embodiment. The attachment member employed in the attachment to a second bone, such as bone 46 in Figs. 2-4, includes opposing parallel arms 60 and 61. Attachment arms 60, 61 define a bone rèceiving space 62 therebetween and are positionable adjacent the exterior surface of bone 46 during attachment. Arm 60 includes a pair of transverse apertures 64 therethrough, and attachment 2~ ~3~13 arm 61 similarly includes a pair of apertures 65 in alignment with apertures 64. During implantation of endoprosthetic joint 15' a bore aligned with apertures 64, 65 may be drilled through bone 46 to allow the introduction of fasteners into bone 46. For example, bolts having heads abutting an outward surface of arm 60, and distal ends which engages nuts tightened against an outward surface of arm 61, may be inserted through the shown apertures and bone 46.
Referring now to Figs. 8 and 9, there is shown one embodiment of a replacement or artificial knuckle, generally deslgnated 70, of the present invention. Knuckle 70 is shown attached to the embodiment of the endoprosthetic joint of Fig. 1.
Knuckle 70 is sized and shaped to fill the potenti~ally wide joint space which often results during the implantation of endoprosthetic joints of this type. Knuckle 70 may be formed of a resilient, plastic material which can closely conform to the portions of endoprosthetic joint 15 which it encapsulates. As shown in Fig. 9, the side portions 71 of knuckle 70 extend around the sides of endoprosthetic joint 15 and include inwardly -extending tabs 74. Tabs 74 are parallelepiped in shape to be received in a friction fit by guide locating module projection receiving cavities 27, 28 on both sides of endoprosthetic joint 15.
Referring now to Fig. lo, there is shown an alternate embodiment of an artificial knuckle, generally designated 80.
Knuckle 80 includes resilient mating portions 81, 82 which cover - opposing sides and top halves of the hinge of endoprosthetic --~~ joint 15. Knuckle portions 81, 82 include complimentary or mating engagement faces, for instance the saw-shaped faces shown in Fig. 10, which mate to form an artificial knuckle which appears continuous when portions 81, 82 are separately attached to joint 15. For proper operation, knuckles 70 should only 2 1 :~ 3 ~ L 3 attach to a single stem portion to permit articulated joint 20 to flex without impairment.
It will be appreciated that while knuckle 70 and 80 may advantageously utilize guide locating modules 27, 28 for attachment to endoprosthetic joint 15, it is within the scope of the invention for other or additional attachment modules to be used for attachment of the artificial knuckles to the endoprosthetic apparatus. For example, recesses in a knuckle which receive projecting tabs serving as modules 27, 28 of joint 15, or projections or recesses of the knuckle which engage complimentary recesses or projections disposed at alternate locations around joint 15, may be used.
Referring now to Fig. 11, there is shown one embodiment of a projecting locking tab for the attachment module of artificial knuckle 80. In this embodiment, the attachment cavity formed in endoprosthetic joint 15, such as module cavity 27, is formed with a square mouth 85 and a substantially parallelepiped interior cavity 84. The insert end of cavity 84 is provided with triangular notches 86 on opposing sides. Projection 90 of knuckle portion 81 includes triangular locking tabs 91 which are shaped complimentary to notches 86. During knuckle attachment, due to the resilient composition of knuckle 80, locking tabs 91 are forced through cavity mouth 85 and snap fit into engagement with notches 86, such that an interlocking engagement results which secures knuckle 80.
Referring now to Figs. 12 - 14, there is shown a pivot hinge suitable for use with the endoprosthetic joint 15 of the present -~ invention. In this embodiment, bone attaching stem 95 includes a ~~ spherical or ball shaped end 97 having an arc shaped through opening 98 as seen in elevational view of Fig. 12 or sectional view of Fig. 14. This spherical end 97 fits into a complimentary radiused end 100 of bone attaching stem 96. End 100 includes two 21 ~ 3 3 13 projecting ears 102 and 104 connected together by means of a rod 106. As shown in Fig. 14, this embodiment of the prosthetic joint 15 is articulated by means of rod 106 sliding through a groove 98. As endoprosthetic joint 15 bends or articulates rod 106 will slide from the top most portion of groove 98 to the bottom of groove 98. The circular arounded outer surface of end 97 slides easily and complimentary with end 100 of bone attaching stem 96. This pivoting hinge provides for realistic digit motion when implanted within a finger or toe. For superior strength and joint life it may be necessary to strengthen the portion about ears 102 and 104 identified as 108 to prevent reverse fluxation or hyperextension of the joint within the finger or toe. It is foreseen that supporting structures of the fingers i.e. tendons and muscles will tend to prevent reverse articulation of endoprosthetic joint 15.
While this invention has been described as having preferred designs, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover these and any other variations, uses, or adaptations of the invention using its general principles.
Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.

Claims (18)

1. In combination, an endoprosthetic apparatus and a guide apparatus, wherein said endoprosthetic apparatus comprises:
a first attachment member insertable into a hollow of a first bone, said first attachment member comprising a bore, wherein said bore resides within the first bone hollow when said first attachment member is inserted into the first bone hollow;
a first guide locating module positioned in spaced relationship with said bore, wherein said first guide locating module resides outside the first bone hollow when said first attachment member is inserted into the first bone hollow;
a fastener receivable within said bore; and a second attachment member, operatively connected to said first attachment member, attachable to a second bone;
wherein said guide apparatus comprises:
a body including a guide bore for guiding formation of a hole in the first bone through which said fastener inserts;
a cooperating locating module, connected to said body, shaped complementarily to said first guide locating module for engagement therebetween to allow operative arrangement of said guide apparatus body relative to said first attachment member for hole formation;
wherein said body guide bore is located along said body at a predetermined position such that said body guide bore and said first attachment member bore are aligned when said cooperating locating module and said first guide locating module engage to operatively arrange said guide apparatus body and said first attachment member.

2. The combination of claim 1 wherein said first attachment member comprises an elongate stem.

3. The combination of claim 1 wherein said cooperating locating module comprises a projection and said first guide locating module comprises a projection receiving cavity.

4. The combination of claim 3 wherein said projection and said projection receiving cavity are each square in cross-sectional shape.

5. The combination of claim 3 wherein said projection and said projection receiving cavity are each hexagonal in cross-sectional shape.

6. The combination of claim 1 wherein said fastener comprises a threaded screw.

7. The combination of claim 1 wherein said first attachment member and said second attachment member are operatively connected by an articulated joint.

8. The combination of claim 7 wherein said articulated joint comprises a dual pivot hinge.

9. The combination of claim 1 wherein said second attachment member comprises a stem insertable into a hollow of the second bone and including a second bore, and wherein said endoprosthetic apparatus further comprises a second guide locating module positioned in spaced relationship with said second bore and a second fastener receivable within said second bore.

10. The combination of claim 1 wherein said second attachment member comprises at least one arm positionable adjacent to the exterior of the second bone, said at least one arm comprising a plurality of fastener receiving apertures.

11. The combination of claim 1 wherein said endoprosthetic apparatus further comprises an artificial knuckle comprising an attachment module engagable with said first guide locating module.

12. An endoprosthetic joint comprising:
a first attachment member attachable to a first bone, said first attachment member comprising at least one arm positionable adjacent to the exterior of the first bone, said at least one arm comprising a plurality of fastener receiving apertures;
an articulated joint operatively connected to said first attachment member; and a second attachment member, operatively connected to said articulated joint, attachable to a second bone.

13. The endoprosthetic joint of claim 12 wherein said at least one arm comprises a first arm and a second arm positionable adjacent to the exterior of the first bone on.
opposite sides of the first bone.

14. The endoprosthetic joint of claim 13 wherein said plurality of fastener receiving apertures in said first arm are aligned with said plurality of fastener receiving apertures in said second arm.

15. An endoprosthetic joint comprising:
a first attachment member attachable to a first bone;
a second attachment member attachable to a second bone;
an articulated joint operatively connecting said first attachment member and said second attachment member;
wherein at least one of said first attachment member and said second attachment member comprises a first type attachment module; and an artificial knuckle structured to at least partially encapsulate said articulated joint, said artificial knuckle comprising a second type attachment module shaped complementarily to said first type attachment module for engagement therewith, wherein one of said first type attachment module and said second type attachment module comprises a projection, and the other of

16 said first type attachment module and said second type attachment module comprises a projection receiving cavity.
16. The endoprosthetic joint of claim 15 wherein said projection receiving cavity comprises at least one locking notch formed in a surface defining said cavity, and wherein said projection comprises at least one locking tab complementarily sized and shaped with said notch for interlocking engagement therebetween.

17. The endoprosthetic joint of claim 15 wherein said artificial knuckle comprises a unitary construction.

18. The endoprosthetic joint of claim 15 wherein said artificial knuckle comprises a multiple piece construction including a first knuckle portion and a second knuckle portion, wherein said first knuckle portion comprises a first mating surface, and wherein said second knuckle portion comprises a second mating surface shaped complementarily to said first mating surface for mating engagement therebetween.