U.S. patent application number 09/792172 was filed with the patent office on 2002-08-29 for knee joint prosthesis.
Invention is credited to Hoeppner, Jacy C., Metzger, Robert G..
Application Number | 20020120340 09/792172 |
Document ID | / |
Family ID | 25156022 |
Filed Date | 2002-08-29 |
United States Patent
Application |
20020120340 |
Kind Code |
A1 |
Metzger, Robert G. ; et
al. |
August 29, 2002 |
Knee joint prosthesis
Abstract
A modular tibial component for a knee joint prosthesis. The
modular tibial component includes a tray, a stem and an adapter
assembly. The tray includes a support surface and downwardly
extending extension having a generally circular shape. The stem
includes a main body portion and an upwardly extending extension.
The adapter assembly connects the tray and the stem. The adapter
assembly includes a first generally cylindrical cavity receiving
the downwardly extending extension of the tray and a second
generally cylindrical cavity receiving the upwardly extension of
the stem.
Inventors: |
Metzger, Robert G.;
(Wakarusa, IN) ; Hoeppner, Jacy C.; (Syracuse,
IN) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
25156022 |
Appl. No.: |
09/792172 |
Filed: |
February 23, 2001 |
Current U.S.
Class: |
623/20.15 ;
623/20.34 |
Current CPC
Class: |
A61F 2002/30538
20130101; A61F 2220/0041 20130101; A61F 2250/0006 20130101; A61F
2002/30357 20130101; A61F 2002/30574 20130101; A61F 2002/30797
20130101; A61F 2002/30339 20130101; A61F 2002/30329 20130101; A61F
2220/0033 20130101; A61F 2002/30405 20130101; A61F 2002/30594
20130101; A61F 2002/30433 20130101; A61F 2230/0021 20130101; A61F
2220/0025 20130101; A61F 2230/0017 20130101; A61F 2002/30133
20130101; A61F 2002/30143 20130101; A61F 2002/30616 20130101; A61F
2/30721 20130101; A61F 2002/30476 20130101; A61F 2230/0015
20130101; A61F 2002/30878 20130101; A61F 2002/30336 20130101; A61F
2002/30604 20130101; A61F 2002/4638 20130101; A61F 2002/30154
20130101; A61F 2002/3079 20130101; A61F 2002/30774 20130101; A61F
2002/30354 20130101; A61F 2/38 20130101 |
Class at
Publication: |
623/20.15 ;
623/20.34 |
International
Class: |
A61F 002/38 |
Claims
What is claimed is:
1. A modular tibial component for a knee joint prosthesis, the
modular tibial component comprising: a tray having a support
surface and a downwardly extending extension having a generally
circular shape; a stem having a main body portion and an upwardly
extending extension; and an adapter assembly connecting the tray
and the stem, the adapter assembly including a first generally
cylindrical cavity receiving the downwardly extending extension of
the tray and a second generally cylindrical cavity receiving the
upwardly extending extension of the stem.
2. The modular tibial component for a knee joint prosthesis of
claim 1, wherein the first generally cylindrical cavity includes a
first central axis and the second generally cylindrical cavity
includes a second central axis, the first and second central axes
being parallel to one another and spaced apart.
3. A modular tibial component for a knee joint prosthesis, the
modular tibial component comprising: a tray having a support
surface and a downwardly extending extension defining a first axis;
a stem having a main body portion and an upwardly extending
extension defining a second axis; an adapter assembly connecting
the tray and the stem, the adapter assembly including a first
cavity receiving the downwardly extending extension of the tray and
a second cavity receiving the upwardly extending extension of the
stem, the adapter assembly being selectively engageable with the
downwardly extending extension to provide a predetermined offset
between the first and second axis in any direction in a transverse
plane.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to a joint
prosthesis and more particularly to a knee joint prosthesis having
a modular tibial component with an offset tibial stem.
BACKGROUND OF THE INVENTION
[0002] A knee joint prosthesis typically comprises a femoral
component and a tibial component. The femoral component and tibial
component are designed to be surgically attached to the distal end
of the femur and the proximal end of the tibia respectively. The
femoral component is further designed to cooperate with the tibial
component in simulating the articulating motion of an anatomical
knee joint. Knee joint prostheses, in combination with ligaments
and muscles, attempt to duplicate natural knee motion as well as
absorb and control forces generated during the range of
flexion.
[0003] While known knee joint prostheses have proven to be
effective in replacing the anatomical knee joint, they nevertheless
have several disadvantages. For example, knee joint prostheses
sometimes lack interchangeability between a femoral component
designed specifically for a right knee or a left knee and a
particular component. In this regard, in a normally shaped tibia,
the central canal is typically offset from the center of the tibial
articulating surfaces or the center of the tibial plateau. The
stems of most prior tibial implants have been positioned centrally
to the implant base or tibial tray. Although a central location of
the stem allows for particular implant to be used for either the
right or left knee, such a stem position is associated with
drawbacks. The primary drawback is that the centrally located stem
was substantially offset from the center of the tibial canal itself
when the base of the implant was aligned with the resected tibial
surface.
[0004] To a more limited extent, it is also known to provide a knee
joint prosthesis with an offset tibia stem. While knee joint
prosthesis with offset tibial stems provide certain identified
advantages, they nevertheless can be the subject of certain
improvement.
SUMMARY OF THE INVENTION
[0005] According to one aspect of the present invention, the
invention relates to a tibial component for a knee joint prosthesis
having an offset stem.
[0006] One particular advantage of the present invention is to
provide a tibial component of a knee joint prosthesis having a
common tibial tray and a plurality of tibial stems with various
offsets for selectively engaging the tibial tray.
[0007] Another advantage of the present invention is to provide a
tibial component of a knee joint prosthesis having a offset modular
stem that securely engages a tibial tray.
[0008] Another advantage of the present invention is to provide a
modular component of a knee joint prosthesis that permits different
degrees of stem offset with minimal inventory.
[0009] Another advantage of the present invention is the provision
of a tibial component of a knee joint prosthesis having a stem
which is offset immediately below a tibial tray.
[0010] Another advantage of the present invention is the provision
of a modular tibial component of a knee joint prosthesis having a
stem that easily and securely engages a tray.
[0011] Another advantage of the present invention is the provision
of a modular tibial component of a knee joint prosthesis which
provides an offset in any direction within the transverse
plane.
[0012] In one form, the present invention provides a modular tibial
component for a knee joint prosthesis. The modular tibial component
includes a tray, a stem and an adapter assembly. The tray includes
a support surface and downwardly extending extension having a
generally circular shape. The stem includes a main body portion and
an upwardly extending extension. The adapter assembly connects the
tray and the stem. The adapter assembly includes a first generally
cylindrical cavity receiving the downwardly extending extension of
the tray and a second generally cylindrical cavity receiving the
upwardly extending extension of the stem.
[0013] Additional advantages and features of the present invention
will become apparent from the following description and appended
claims, taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0015] FIG. 1 is a front view illustration of a knee joint
prosthesis, the knee joint prosthesis illustrated to include a
first adapter assembly for providing a first predetermined offset
according to the teachings of a preferred embodiment of the present
invention.
[0016] FIG. 2 is front view of a modular tibial component for a
knee joint prosthesis including a second adapter assembly according
to the teachings of the present invention for providing a second
predetermined offset.
[0017] FIG. 3 is front view of a modular tibial component for a
knee joint prosthesis including a third adapter assembly according
to the teachings of the present invention which does not include an
offset.
[0018] FIG. 4 is a bottom view of the tibial tray of the knee joint
prosthesis of FIG. 1.
[0019] FIG. 5 is a cross-sectional view taken along the line 5-5 of
FIG. 4.
[0020] FIG. 6 is an exploded view of a portion of the modular
tibial component of FIG. 1.
[0021] FIG. 7 is a cross-sectional view taken along the line 7-7 of
FIG. 6.
[0022] FIG. 8 is a cross-sectional view taken along the line 8-8 of
FIG. 6.
[0023] FIG. 9 is a cross-sectional view taken along the line 9-9 of
FIG. 6.
[0024] FIG. 10 is an enlarged view of the stem insert according to
the present invention and shown in FIG. 6.
[0025] FIG. 11 is an exploded view similar to FIG. 6, illustrating
a portion of the modular tibial component of FIG. 2.
[0026] FIG. 12 is a cross-sectional view taken along the line 12-12
of FIG. 11.
[0027] FIG. 13 is a cross-sectional view taken along the line 13-13
of FIG. 11.
[0028] FIG. 14 is a cross-sectional view taken along the line 14-14
of FIG. 11.
[0029] FIG. 15 is another exploded view similar to FIG. 6,
illustrating a portion of the modular tibial component of FIG.
3.
[0030] FIG. 16 is a cross-sectional view taken along the line 16-16
of FIG. 15.
[0031] FIG. 17 is an enlarged view of the locking insert of FIG.
15.
[0032] FIG. 18 is an illustration of a modular femoral component
for a knee joint prosthesis according to the teachings of the
present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] With initial reference to FIG. 1, a knee joint prosthesis
constructed in accordance with the teachings of a preferred
embodiment of the present invention is illustrated and generally
identified at reference number 10. The knee joint prosthesis 10 is
generally shown to include a tibial component 12 and a femoral
component 14. The tibial component 12 supports a bearing 16 which
engages an articulation surface 18 of the femoral component 14.
Insofar as the present invention is concerned, it will be
understood that the femoral component 14 and the bearing 16 shown
in FIG. 1 are conventional in construction.
[0034] The tibial component 12 illustrated in FIG. 1 will be
understood to be modular in construction and generally include a
stem 20, a tray 22, and a first adapter assembly 24. In a manner
which will be discussed more fully below, the adapter assembly 24
connects the tray 22 and the stem 20 so as to provide an offset to
the stem 20 in the transverse plane. Explaining further, when the
stem 20 is attached to the tray 22 through the first adapter
assembly 24, a central axis of the stem 20 is offset from a central
axis 27 of a downwardly extending extension 30 of the tray 22. In
the embodiment illustrated, the first adapter assembly 24 provides
a first offset of approximately 5 mm. It will become apparent below
that the offset can be in any direction in the transverse
plane.
[0035] With brief reference to FIGS. 2 and 3, second and third
adapter assemblies 28 and 30 according to the teachings of the
preferred embodiment of the present invention are illustrated,
respectively. The second and third adapter assemblies 28 and 30 are
shown connecting the tray 22 and stem 20 of FIG. 1. As will be
discussed more fully below, the second adapter assembly 28 provides
a second offset which in the embodiment illustrated is
approximately 2.5 mm. The third adapter assembly is a neutral
adapter assembly 30 and does not provide any offset. Explaining
further, the central axis 26 of the stem 20 is aligned with the
central axis 27 of the downwardly extending extension 29 of the
tray 22. It will be appreciated by those skilled in the art that
the particular degrees of offset provided by the various adapter
assemblies 24, 28, and 30 of the present invention are strictly a
matter of design choice. Alternate offsets will be understood to
fall within the scope of the present invention.
[0036] With continued reference to FIG. 1 and additional reference
to FIGS. 4 through 10, the first adapter assembly 24 will be
further described. The first adapter assembly 24 is illustrated to
generally include an adapter body 32, a locking insert member 34
and a stem insert member 36. The adapter body 32 of the first
adapter assembly 24 is shown to include a first generally
cylindrical cavity 38 for receiving the downwardly extending
extension 29 of the tray 22 and a second generally cylindrical
cavity 40 for receiving and upwardly extending extension 42 of the
stem 20. The first generally cylindrical cavity 38 includes a first
central axis 42 and the second generally cylindrical cavity 40
includes a second generally cylindrical axis 44. In the embodiment
illustrated, the first central axis 42 and the second central axis
44 are parallel to one another and spaced apart. Insofar as the
first adapter assembly 24 provides a 5 mm offset, the first and
second central axes 42 and 44 are spaced apart 5 mm.
[0037] The first generally cylindrical cavity 38 includes a first
portion 46 for directly receiving the downwardly extending
extension 29 of the tray 22 and a second reduced diameter portion
48 which receives the locking insert 34. The first portion 46
preferably tapers slightly as it extends into the adapter body 32
from a top end of the adapter body 32. The second generally
cylindrical cavity 40 similarly includes a first portion 50 and a
second portion 52 of reduced diameter. The first portion 50
preferably tapers slightly as it extends into the adapter body 32
from a lower end 54 of the adapter body 32. The second portion 52
of the second generally cylindrical cavity 40 is shown to intersect
the second portion 48 of the first generally cylindrical cavity 38.
In a manner to be described further below, the stem insert 36 is
partially disposed within the first portion 50 and extends into the
second portion 52 where it engages the locking insert member
34.
[0038] With particular reference to FIG. 10, the stem insert member
36 is illustrated to include a lower portion 60 which is externally
threaded for engaging an internally threaded aperture of the
upwardly extending extension 42 of the stem 20. The stem insert
member 36 further includes a central portion 62 having a hexagonal
or other suitable cross-section which can be engaged by a tool (not
shown) for rotating the stem insert member 36 into the stem 20.
Further, the stem insert member 36 includes an upper end 64
including an enlarged diameter head 66 which extends into the
second portion 52 of the second generally cylindrical cavity
40.
[0039] With particular reference to the cross-sectional views of
FIGS. 8 and 9, the locking insert member 34 will be further
described. The locking insert member 34 includes an upper portion
having an internally threaded aperture 68 and having a square,
hexagonal or other suitable cross section that can be engaged by a
tool (not shown). The internally threaded aperture 68 threadably
receives a fastener 70 which extends through a central aperture 72
provided in the tray 22. The locking insert member 34 additionally
includes a radially extending segment 74 for engaging the head 66
of the stem insert member 36.
[0040] Upon selection by the surgeon of the first adapter assembly
24, the stem insert member 36 is screwed into the stem 20. Next,
the adapter body 32 is placed over the upwardly extending extension
42 of the stem 20 such that the upwardly extending portion 42 is
received in a press fit within the first portion 50 of the first
generally cylindrical aperture 40 and the upper end 64 of the stem
insert member 36 extends into the reduced diameter second portion
52 of the second generally cylindrical cavity 40. At this point,
the locking insert member 34 is inserted into the first generally
cylindrical cavity 38 with the radially extending segment 74
opposite the side of the reduced diameter portion 48 which
intersects the reduced diameter portion 52. Upon complete
insertion, the locking insert member 34 is rotated approximately
between 180.degree. and 270.degree. such that the radially
extending portion 74 engages the enlarged head 66 of the stem
insert member 36.
[0041] The adapter body 32 is rotated about the axis 27 to provide
the offset in the desired direction. The first portion 46 of the
first generally cylindrical cavity 38 is now press fit onto the
downwardly extending extension 29 of the tray 22. The stem 20 is
secured to the tray 22 by the threaded fastener 70 which extends
through the aperture 72 and threadably engages the internally
threaded aperture 68 of the locking insert member 34. Rotation of
the threaded fastener 70 in a clockwise direction causes the
locking insert member 34 to be drawn towards the tray 22 and a
secure connection to be established between the tray 22 and the
stem 20.
[0042] With reference now to FIGS. 2 and 11 through 14, the second
adapter assembly 28 of the present invention will now be described.
The second adapter assembly 28 is illustrated to generally include
an adapter body 80, a locking insert member 82 and a stem insert
member 84. The stem insert member 84 is identical to stem insert
member 36 described above.
[0043] The adapter body 80 of the second adapter assembly 28 is
shown to include a first generally cylindrical cavity 86 for
receiving the downwardly extending extension 29 of the tray 22 and
a second generally cylindrical cavity 88 for receiving the upwardly
extending extension 42 of the stem 20. The first generally
cylindrical cavity 86 includes a first central axis 90 and the
second generally cylindrical cavity 88 includes a second generally
cylindrical axis 92. In the embodiment illustrated, the first
central axis 90 and the second central axis 92 are parallel to one
another and spaced apart. Insofar as the second adapter assembly 80
provides a 2.5 mm offset, the first and second central axes 90 and
92 are spaced apart 2.5 mm.
[0044] The first generally cylindrical cavity 86 includes a first
portion 94 for directly receiving the downwardly extending
extension 29 of the tray 22 and a second reduced diameter portion
96 which receives the locking insert 82. As with the first adapter
assembly 24, the first portion 94 preferably tapers slightly as it
extends into the adapter body 80 from a top end. The second
generally cylindrical cavity 88 similarly includes a first portion
98 and a second portion 100 of reduced diameter. The first portion
98 preferably tapers slightly as it extends into the adapter body
80 from a lower end 102 of the adapter body 80. The second portion
100 of the second generally cylindrical cavity 88 is shown to
intersect the second portion 96 of the first generally cylindrical
cavity 86.
[0045] With particular reference to the cross-sectional views of
FIGS. 13 and 14, the locking insert member 82 will be further
described. The locking insert member 82 includes an upper portion
having an internally threaded aperture 104 and having a square,
hexagonal or other suitable cross section that can be engaged by a
tool. The internally threaded aperture 104 threadably receives the
fastener 70 which extends through the central aperture 72 in the
tray 22. The locking insert member 82 additionally includes a
radially extending segment 106 defining a cavity 108 for engaging
the head 66 of the stem insert member 36. The aperture 108 includes
a non-cylindrical opening for receiving the head 66 of the stem
insert member 36 and retaining the head 66 upon rotation in the
manner discussed above with respect to the first adapter assembly
24.
[0046] With reference now to FIGS. 3 and 15 through 17, the third
adapter assembly 30 of the present invention will now be described.
The third adapter assembly 30 is illustrated to generally include
an adapter body 110 and a locking insert member 112. The adapter
body 110 of the third adapter assembly 30 is shown to include a
first generally cylindrical cavity 114 for receiving the downwardly
extending extension 29 of the tray 22 an a second generally
cylindrical cavity 116 for receiving the upwardly extending
extension 42 of the stem 20. The first generally cylindrical cavity
includes a first central axis 118 and the second generally
cylindrical cavity includes a second generally cylindrical axis
120. In the embodiment illustrated, the first central axis 118 and
the second central axis 120 are coincident as the third adapter
assembly 30 does not provide any offset.
[0047] The first generally cylindrical cavity 114 includes a first
portion 122 for directly receiving the downwardly extending
extension 29 of the tray 22 and a second reduced diameter portion
124 which receives the locking insert 112. The first portion 122
preferably tapers slightly as it extends into the adapter body 110
from an upper end. The second generally cylindrical cavity 116
similarly includes a first portion 126 and a second portion 128 of
reduced diameter. The first portion 126 preferably tapers slightly
as it extends into the adapter body 110 from a lower end 130 of the
adapter body 110. The second portion 128 of the second generally
cylindrical cavity 126 is shown to communicate with the second
portion 124 of the first generally cylindrical cavity 114.
[0048] With particular reference to FIG. 17, the locking insert
member 112 is illustrated to include a lower portion 132 which is
externally threaded for engaging the internally threaded aperture
of the upwardly extending extension 42 of the stem 20. The locking
insert member 112 further includes a central portion 134 and an
upper portion 136. The upper portion has a square, hexagonal or
other suitable cross section which can be engaged by a tool (not
shown) for rotating the locking insert member 112 into the stem 20.
The internally threaded aperture 138 threadably receives the
fastener 70 which extends through the central aperture 72 provided
in the tray 22.
[0049] Turning finally to FIG. 18, a modular femoral component for
a knee joint prosthesis of the present invention is generally
identified at reference 200. The embodiment of FIG. 18 illustrates
application of the teachings of the present invention adapted to a
modular femoral component 200. The modular femoral component 200
includes an articulating member 202, a stem 204 and an adapter
assembly 206. While not shown in great detail, it will be
understood by those skilled in the art that the adapter assembly
206 is substantially identical to the first adapter assembly 24
described above. In this regard, the adapter assembly 206 connects
the articulating member 202 and the stem 204 and provides an offset
between an upwardly extending extension 208 of the articulating
member and a downwardly extension 210 of the stem 204. The adapter
assembly 206 will be understood to include an adapter body, locking
insert member and stem insert member substantially identical to
that described above with respect to the first adapter assembly 24.
Alternatively, it will be understood that the adapter assembly of
the modular femoral component 200 may be similar to either of the
second and third adapter assemblies 28 and 30.
[0050] While the invention has been described in the specification
and illustrated in the drawings with reference to a preferred
embodiment, it will be understood by those skilled in the art that
various changes may be made and equivalents may be substituted for
elements thereof without departing from the scope of the invention
as defined in the claims. In addition, many modifications may be
made to adapt a particular situation or material to the teachings
of the invention without departing from the essential scope
thereof. Therefore, it is intended that the invention not be
limited to the particular embodiment illustrated by the drawings
and described in the specification as the best mode presently
contemplated for carrying out this invention, but that the
invention will include any embodiments falling within the
description of the appended claims.
* * * * *