Note: Descriptions are shown in the official language in which they were submitted.
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
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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
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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
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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;
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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
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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
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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
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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
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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.
I3
