U.S. patent application number 09/792174 was filed with the patent office on 2002-08-29 for method and apparatus for acetabular reconstruction.
Invention is credited to Gibbs, Phillip M..
Application Number | 20020120342 09/792174 |
Document ID | / |
Family ID | 25156031 |
Filed Date | 2002-08-29 |
United States Patent
Application |
20020120342 |
Kind Code |
A1 |
Gibbs, Phillip M. |
August 29, 2002 |
METHOD AND APPARATUS FOR ACETABULAR RECONSTRUCTION
Abstract
An acetabular prosthesis for implantation in an acetabulum and
surrounding pelvis is described. The acetabular prosthesis includes
an acetabular cup having a substantially concave inner surface and
a substantially convex outer surface, wherein an area defining a
groove is located on the outer surface of the acetabular cup. An
optional spacer member, having a raised ridge formed on a surface
thereof, slidably engages the groove. The spacer provides
augmentation and load bearing support in cases where bone tissue
loss has occurred in and around the acetabulum. A fastener, such as
a surgical screw, is used to secure the acetabular cup, and the
optional spacer, to the acetabulum. At least one attachment member
is integrally formed with the acetabular cup for fastening to a
surface of the pelvis, such as the ilium and/or the ischium.
Another optional spacer member is provided for the attachment
member to provide augmentation around the attachment points on the
pelvis. A fastener, such as a surgical screw, is used to secure the
attachment member, and the other optional spacer, to the pelvis.
The described acetabular prosthesis is especially useful in
revision hip implant procedures where significant bone tissue loss
has occurred either in or around the acetabulum and/or the
pelvis.
Inventors: |
Gibbs, Phillip M.; (Winona
Lake, IN) |
Correspondence
Address: |
Harness, Dickey & Pierce, P.L.C.
P.O. Box 828
Bloomfield Hills
MI
48303-0828
US
|
Family ID: |
25156031 |
Appl. No.: |
09/792174 |
Filed: |
February 23, 2001 |
Current U.S.
Class: |
623/22.32 |
Current CPC
Class: |
A61F 2/34 20130101; A61F
2/30734 20130101; A61F 2250/0058 20130101; A61F 2/30724 20130101;
A61F 2002/30535 20130101 |
Class at
Publication: |
623/22.32 |
International
Class: |
A61F 002/32 |
Claims
What is claimed is:
1. An acetabular prosthesis for implantation in an acetabulum and
surrounding pelvis, the acetabular prosthesis comprising: an
acetabular cup having a substantially concave inner surface and a
substantially convex outer surface, the outer surface operable to
be received in the acetabulum; an area defining a receptacle
located in the outer surface of the acetabular cup; a spacer member
having an appendage formed on a surface thereof for mating
engagement with the receptacle; wherein the spacer member is
disposed between the outer surface of the acetabular cup and the
acetabulum; and an attachment member integral with the acetabular
cup for fastening to a surface of the pelvis.
2. The invention according to claim 1, wherein the receptacle
comprises a groove.
3. The invention according to claim 1, wherein the appendage is
slidably received in the receptacle.
4. The invention according to claim 1, wherein the appendage
comprises a raised ridge.
5. The invention according to claim 1, wherein the acetabular cup
include a throughbore.
6. The invention according to claim 5, wherein the throughbore
includes a threaded surface.
7. The invention according to claim 5, wherein the receptacle is
bisected by the throughbore.
8. The invention according to claim 1, wherein the receptacle is
located in proximity to a peripheral surface of the acetabular
cup.
9. The invention according to claim 1, wherein the acetabular cup
has a substantially arcuate peripheral surface.
10. The invention according to claim 1, wherein the spacer member
has a substantially curved surface.
11. The invention according to claim 1, wherein the appendage has a
substantially curved surface.
12. The invention according to claim 1, wherein the spacer member
has a throughbore.
13. The invention according to claim 12, wherein the appendage is
bisected by the throughbore.
14. The invention according to claim 12, wherein the throughbore
includes a threaded surface.
15. The invention according to claim 1, wherein the attachment
member is contiguous with the inner surface of the acetabular
cup.
16. The invention according to claim 1, wherein the attachment
member has a throughbore.
17. The invention according to claim 1, wherein the attachment
member is substantially planar.
18. The invention according to claim 1, wherein the attachment
member extends outwardly away from the acetabular cup.
19. The invention according to claim 1, wherein the attachment
member has a first portion and a second portion, wherein the second
portion is angled with respect to the first portion.
20. The invention according to claim 1, wherein the surface of the
pelvis is selected from the group consisting of the ilium, the
ischium, and combinations thereof.
21. The invention according to claim 1, further comprising a second
spacer member.
22. The invention according to claim 21, wherein the second spacer
member is adjacent to the attachment member.
23. The invention according to claim 21, wherein the second spacer
member includes a throughbore.
24. The invention according to claim 23, wherein the throughbore
includes a threaded surface.
25. The invention according to claim 21, wherein the second spacer
member includes a first surface and a second opposed and spaced
surface.
26. The invention according to claim 25, wherein the first surface
is substantially parallel to the second surface.
27. The invention according to claim 25, wherein the first surface
is substantially non-parallel to the second surface.
28. The invention according to claim 1, further comprising a second
attachment member.
29. The invention according to claim 28, further comprising a third
attachment member.
30. An acetabular prosthesis for implantation in an acetabulum and
surrounding pelvis, the acetabular prosthesis comprising: an
acetabular cup having a substantially concave inner surface and a
substantially convex outer surface, the outer surface operable to
be received in the acetabulum; an attachment member integral with
the acetabular cup for fastening to a surface of the pelvis; and a
spacer member adjacent to the attachment member; wherein the spacer
member is disposed between the attachment member and the surface of
the pelvis.
31. The invention according to claim 30, wherein the acetabular cup
includes an area defining a groove located in the outer surface
therein.
32. The invention according to claim 31, further comprising a
second spacer member having an area defining a raised ridge formed
on a surface thereof for sliding engagement with the groove,
wherein the second spacer member is disposed between the outer
surface of the acetabular cup and the acetabulum.
33. The invention according to claim 30, wherein the acetabular cup
includes a through bore.
34. The invention according to claim 33, wherein the throughbore
includes a threaded surface.
35. The invention according to claim 33, wherein the groove is
bisected by the throughbore.
36. The invention according to claim 31, wherein the groove is
located in proximity to a peripheral surface of the acetabular
cup.
37. The invention according to claim 30, wherein the acetabular cup
has a substantially arcuate peripheral surface.
38. The invention according to claim 32, wherein the second spacer
member has a substantially curved surface.
39. The invention according to claim 32, wherein the raised ridge
has a substantially curved surface.
40. The invention according to claim 32, wherein the second spacer
member has a throughbore.
41. The invention according to claim 40, wherein the raised ridge
is bisected by the throughbore.
42. The invention according to claim 40, wherein the throughbore
includes a threaded surface.
43. The invention according to claim 30, wherein the attachment
member is contiguous with the inner surface of the acetabular
cup.
44. The invention according to claim 30, wherein the attachment
member has at least one throughbore.
45. The invention according to claim 30, wherein the attachment
member is substantially planar.
46. The invention according to claim 30, wherein the attachment
member extends outwardly away from the acetabular cup.
47. The invention according to claim 30, wherein the attachment
member has a first portion and a second portion, wherein the second
portion is angled with respect to the first portion.
48. The invention according to claim 30, wherein the surface of the
pelvis is selected from the group consisting of the ilium, the
ischium, and combinations thereof.
49. The invention according to claim 30, wherein the spacer member
includes at least one throughbore.
50. The invention according to claim 49, wherein the throughbore
includes a threaded surface.
51. The invention according to claim 30, wherein the spacer member
includes a first surface and a second opposed and spaced
surface.
52. The invention according to claim 51, wherein the first surface
is substantially parallel to the second surface.
53. The invention according to claim 51, wherein the first surface
is substantially non-parallel to the second surface.
54. The invention according to claim 30, further comprising a
second attachment member.
55. The invention according to claim 54, further comprising a third
attachment member.
56. A method for implanting an acetabular prosthesis in an
acetabulum and surrounding pelvis, comprising: providing an
acetabular cup having a substantially concave inner surface and a
substantially convex outer surface, the outer surface operable to
be received in the acetabulum, the outer surface of the acetabulum
cup having an area defining a receptacle located therein, the
acetabular cup having an attachment member integral therewith for
fastening to a surface of the pelvis; providing a spacer member
having an appendage formed on a surface thereof for mating
engagement with the receptacle; securing the spacer member to the
outer surface of the acetabular cup; engaging the outer surface of
acetabular cup with the acetabulum such that the spacer member is
disposed between the outer surface of the acetabular cup and the
acetabulum; securing the acetabular cup to the acetabulum; and
securing the attachment member to the surface of the pelvis.
57. A method for implanting an acetabular prosthesis in an
acetabulum and surrounding pelvis, comprising: providing an
acetabular cup having a substantially concave inner surface and a
substantially convex outer surface, the outer surface operable to
be received in the acetabulum, the acetabular cup having an
attachment member integral with the acetabular cup for fastening to
a surface of the pelvis; providing a spacer member adjacent to the
attachment member; securing the spacer member to the attachment
member; engaging the outer surface of acetabular cup with the
acetabulum such that the spacer member is disposed between the
attachment member and the surface of the pelvis; securing the
acetabular cup to the acetabulum; and securing the spacer member
and the attachment member to the surface of the pelvis.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to a method and apparatus
for use in orthopedic surgery and, more particularly, to a method
and apparatus for providing a modular acetabular prosthesis having
various modular attachment components for use during an orthopedic
surgical procedure.
BACKGROUND OF THE INVENTION
[0002] A natural hip joint may undergo degenerative changes due to
a variety of etiologies. When these degenerative changes become so
far advanced and irreversible, it may ultimately become necessary
to replace a natural hip joint with a prosthetic hip. When
implantation of such a hip joint prosthesis becomes necessary, the
head of the natural femur is first resected and a cavity is created
within the intramedullary canal of the host femur for accepting the
hip prosthesis. The hip prosthesis may be inserted and supported
within the host femur by cementing the hip prosthesis within the
host femur. Alternatively, the hip prosthesis may be impacted into
the host femur so that it is snugly fit and supported by the host
femur. If the acetabulum also needs repair, all remnants of
articular cartilage are generally removed from the acetabulum and
an acetabular prosthesis which will accommodate the head or ball of
the hip prosthesis is affixed to the acetabulum. The acetabular
prosthesis is affixed to the acetabulum by means of cement, screws
or other appropriate fixation means.
[0003] Due to any number of reasons, however, a small portion of
patients that undergo such orthopedic surgical procedures may
require subsequent revision surgery to replace the prosthetic
device with a new prosthetic device generally referred to as a
revision prosthesis. One example of such a device is generally
known as a protrusio cage.
[0004] In this regard, a revision acetabular prosthesis will
generally include additional mounting points, such as integral
extension members or hooks that provide additional stability for
the revision acetabular prosthesis. These additional mounting
points are generally required due to additional bone loss or
defects exhibited at the acetabulum, such as collar/rim defects or
pelvic discontinuity defects.
[0005] Various types of revision acetabular prostheses are
currently available and different surgeons prefer different types
of revision acetabular prostheses. Some surgeons prefer to use what
is known as an ilium flange that is formed integral with the
acetabular prosthesis and enables further securement of the
acetabular prosthesis in the ilium region of the pelvis. Other
surgeons prefer to use what is known as an obturator hook that is
able to provide inferior fixation of the acetabular prosthesis by
engaging the obturator foramen which is a large aperture adjacent
the acetabulum. Because of this, a hospital must maintain a large
inventory of different revision acetabular cups to meet the various
surgeons' preferences. Moreover, the surgeon will generally have to
have several revision acetabular cups available during surgery to
account for any type of condition that may arise during the
surgical procedure. This increased inventory of prosthetic devices
increases the overall hospital costs and inventory control.
Furthermore, by requiring the multiple revision acetabular cups to
be available during the surgical procedure, multiple prosthetic
devices must be sterilized prior to the surgical procedure, thereby
increasing the surgical time, cost and complexity.
[0006] As previously noted, during hip revision procedures,
surgeons often encounter significant defects due to osteolysis at
the acetabular implant site or due to the removal of bone tissue
that has become attached to the removed acetabular implant. These
defects are usually filled with bulk bone allograft, bone cement,
or morselized bone graft. Each material type raises it's own set of
concerns.
[0007] With respect to bulk bone allograft, many doubts exist as to
whether significant portions of a bulk allograft actually become
viable over time. Dead allograft may not provide long term
structural support. Additionally, higher infection rates are
sometimes connected to the use of bulk allograft. Finally, bulk
allograft is also expensive and sometimes unavailable or difficult
to obtain.
[0008] With respect to bone cement, when defects are filled with
bone cement, subsequent revision procedures may be made more
difficult because there is even less bone tissue to work with.
[0009] With respect to morselized bone graft, this has become the
material of choice; however, it may not provide significant
structural support. Motion of the acetabular implant is of real
concern. For example, motion can prevent bone tissue from
infiltrating the porous surface of the acetabular implant and thus
can place too much load on a thin walled acetabular implant and
screws, potentially causing them to fail. Additionally, morselized
bone graft is very expensive and is sometimes unavailable or
difficult to obtain.
[0010] What is needed then is a method and apparatus for providing
a modular acetabular prosthesis having various modular attachment
components for use during an orthopedic surgical procedure. This
will, in turn, provide more surgical flexibility during
implantation of the acetabular prosthesis, provide the surgeon with
a variety of surgical options at the time of the surgical
procedure, provide a universal acetabular cup that can be
configured for use in many circumstances, reduce hospital inventory
and inventory tracking requirements, and reduce the overall
surgical time, cost and complexity.
SUMMARY OF THE INVENTION
[0011] In accordance with a first embodiment of the present
invention, an acetabular prosthesis for implantation in an
acetabulum and surrounding pelvis is provided, the acetabular
prosthesis comprising: (1) an acetabular cup having a substantially
concave inner surface and a substantially convex outer surface, the
outer surface operable to be received in the acetabulum; (2) an
area defining a receptacle located in the outer surface of the
acetabular cup; (3) a spacer member having an appendage formed on a
surface thereof for mating engagement with the receptacle, wherein
the spacer member is disposed between the outer surface of the
acetabular cup and the acetabulum; and (4) an attachment member
integral with the acetabular cup for fastening to a surface of the
pelvis.
[0012] In accordance with a second embodiment of the present
invention, an acetabular prosthesis for implantation in an
acetabulum and surrounding pelvis is provided, the acetabular
prosthesis comprising: (1) an acetabular cup having a substantially
concave inner surface and a substantially convex outer surface, the
outer surface operable to be received in the acetabulum; (2) an
attachment member integral with the acetabular cup for fastening to
a surface of the pelvis; and (3) a spacer member adjacent to the
attachment member, wherein the spacer member is disposed between
the attachment member and the surface of the pelvis.
[0013] In accordance with a third embodiment of the present
invention, a method for implanting an acetabular prosthesis in an
acetabulum and surrounding pelvis is provided, comprising: (1)
providing an acetabular cup having a substantially concave inner
surface and a substantially convex outer surface, the outer surface
operable to be received in the acetabulum, the outer surface of the
acetabulum cup having an area defining a receptacle located
therein, the acetabular cup having an attachment member integral
therewith for fastening to a surface of the pelvis; (2) providing a
spacer member having an appendage formed on a surface thereof for
mating engagement with the receptacle; (3) securing the spacer
member to the outer surface of the acetabular cup; (4) engaging the
outer surface of acetabular cup with the acetabulum such that the
spacer member is disposed between the outer surface of the
acetabular cup and the acetabulum; (5) securing the acetabular cup
to the acetabulum; and (6) securing the attachment member to the
surface of the pelvis.
[0014] In accordance with a fourth embodiment of the present
invention, a method for implanting an acetabular prosthesis in an
acetabulum and surrounding pelvis is provided, comprising: (1)
providing an acetabular cup having a substantially concave inner
surface and a substantially convex outer surface, the outer surface
operable to be received in the acetabulum, the acetabular cup
having an attachment member integral with the acetabular cup for
fastening to a surface of the pelvis; (2) providing a spacer member
adjacent to the attachment member; (3) securing the spacer member
to the attachment member; (4) engaging the outer surface of
acetabular cup with the acetabulum such that the spacer member is
disposed between the attachment member and the surface of the
pelvis; (5) securing the acetabular cup to the acetabulum; and (6)
securing the spacer member and the attachment member to the surface
of the pelvis.
[0015] A more complete appreciation of the present invention and
its scope can be obtained from the following detailed description
of the invention, the drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The present invention will become more fully understood from
the detailed description and the accompanying drawings,
wherein:
[0017] FIG. 1 is a rear perspective view of an acetabular
prosthesis, in accordance with one embodiment of the present
invention;
[0018] FIG. 2 is another rear perspective view of an acetabular
prosthesis, in accordance with one embodiment of the present
invention;
[0019] FIG. 3 is a rear elevational view of an acetabular
prosthesis, in accordance with one embodiment of the present
invention;
[0020] FIG. 4 is a rear plan view of an acetabular prosthesis, in
accordance with one embodiment of the present invention;
[0021] FIG. 5 is a front plan view of an acetabular prosthesis, in
accordance with one embodiment of the present invention;
[0022] FIG. 6 is a side perspective view of several acetabular
spacer members for an acetabular prosthesis, in accordance with one
embodiment of the present invention;
[0023] FIG. 7 is a bottom plan view of several acetabular spacer
members for an acetabular prosthesis, in accordance with one
embodiment of the present invention;
[0024] FIG. 8 is a top perspective view of several acetabular
spacer members for an acetabular prosthesis, in accordance with one
embodiment of the present invention;
[0025] FIG. 9 is a bottom perspective view of several acetabular
spacer members for an acetabular prosthesis, in accordance with one
embodiment of the present invention;
[0026] FIG. 10 is a front perspective view of two attachment spacer
members for an acetabular prosthesis, in accordance with one
embodiment of the present invention;
[0027] FIG. 11 is a top plan view of two attachment spacer members
for an acetabular prosthesis, in accordance with one embodiment of
the present invention; and
[0028] FIG. 12 is a side perspective view of two attachment spacer
members for an acetabular prosthesis, in accordance with one
embodiment of the present invention.
[0029] The same reference numerals refer to the same parts
throughout the various Figures.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The following description of the preferred embodiments
concerning a method and apparatus for providing a modular
acetabular prosthesis for use in orthopedic surgical procedures are
merely exemplary in nature and are not intended to limit the
invention or its application or uses. Moreover, while the present
invention is described in detail below with reference to performing
a revision type implantation procedure, it will be appreciated by
those skilled in the art that the present invention is clearly not
limited to only revision type orthopedic surgical procedures and
may be used with various other orthopedic surgical procedures as
well.
[0031] Referring to FIGS. 1-5, an acetabular prosthesis 10,
according to the general teachings of the present invention, is
shown. The acetabular prosthesis 10 includes a modified
hemispherical acetabular cup 12. The acetabular cup 12 is said to
be "hemispherical" in that it is not a perfect hemisphere; but
rather, it includes an arcuate portion 14 extending along the
periphery thereof without extending beyond the hemisphere of the
acetabular cup 12.
[0032] The acetabular cup 12 is preferably constructed from any
suitable biocompatible material, such as titanium, stainless steel,
titanium alloy, cobalt-chrome-molybdenum alloy, and the like.
[0033] It should be noted that the acetabular cup 12 would normally
also be associated with other components, such as a congruent shell
or bearing liner (not shown) retained within the acetabular cup 12,
via bone cement or a ring lock (not shown), which are not depicted
for purposes of clarity.
[0034] The acetabular cup 12 preferably includes a substantially
concave inner surface 16 and a substantially convex outer surface
18, wherein the outer surface 18 is operable to be received in the
acetabulum. The inner surface 16 is preferably smooth, whereas the
outer surface 18 may be smooth or roughened with a porous surface
layer (not shown) to facilitate bone tissue in-growth.
[0035] An area defining an optional receptacle or groove 20 is
located in at least a portion of the outer surface 18 of the
acetabular cup 12. The groove 20 preferably includes tapered end
portions 22, 24. The groove 20 is preferably located in proximity
to a peripheral surface of the acetabular cup 12, and generally in
the superior region of the acetabular cup 12. The exact purpose of
the groove 20 will be explained later in detail.
[0036] The acetabular cup 12 preferably includes at least one, and
more preferably, a plurality of throughbores 26 located therein. It
should be noted that the groove 20 is bisected by at least one of
the throughbores 26. The throughbores 26 provide a number of
functions, such as enabling fastening members (not shown) to pass
through the acetabular cup 12. Additionally, the throughbores 26
provide for the infiltration of bone cement to improve adhesion, as
well as providing for new bone tissue in-growth. At least one of
the throughbores 28 includes a threaded surface 30 thereon for
receiving an insertion instrument (not shown) for properly aligning
the acetabular prosthesis 10 within the acetabulum. Throughbore 28
also includes a recessed area 28A which permits the insertion
instrument (not shown) to securely engage the acetabular cup 12 and
permits controlled rotation of same. It will be noted that any
graft material and/or bone cement should preferably be placed into
the acetabulum before securing the acetabular cup 12 thereto.
[0037] A more specific description of the typical installation of
an acetabular prosthesis can be found in U.S. Pat. Nos. 5,314,490;
5,326,367; 5,326,368; 5,702,477; 5,871,548; 5,931,870; and
6,162,257, the entire specifications of which are incorporated
herein by reference.
[0038] The acetabular cup 12 preferably includes at least one, and
more preferably, three substantially rigid attachment or extension
members 32, 34, and 36 integrally formed with the acetabular cup 12
for fastening the acetabular prosthesis 10 to at least a portion of
one or more surfaces of the pelvis (not shown), such as the ilium
and/or the ischium. Preferably, attachment member 32 is used for
attachment to the ischium, whereas attachment members 34 and 36 are
used for attachment to various surfaces of the ilium (e.g.,
anterior and posterior).
[0039] Attachment member 32 is shown as being substantially
triangularly shaped; however, it is envisioned that the shape may
be altered to other configurations. It will be noted that
attachment member 32 has two distinct portions, i.e., a first
substantially curved portion 32A originating from, and contiguous
with, the inner surface 16 of the acetabular cup 12, and a second
substantially planar portion 32B extending out from, and angling
away from, the first portion 32A. The curvature profile may be
modified to meet any anatomical requirements.
[0040] Attachment member 32 preferably includes at least one, and
more preferably, a plurality of throughbores located therein. In
this view, a throughbore 38 is provided in the curved portion 32A
and another throughbore 40 is provided in the planar portion 32B.
The throughbores 38, 40 provide a number of functions, such as
enabling fastening members such as a surgical screw (not shown) to
pass therethrough in order to allow the fastening member 32 to be
secured to the ischium.
[0041] Attachment member 34 is shown as being substantially
rectangularly shaped; however, it is envisioned that the shape may
be altered to other configurations. It will be noted that
attachment member 34 has two distinct portions, i.e., a first
substantially curved portion 34A originating from, and contiguous
with, the inner surface 16 of the acetabular cup 12, and a second
substantially planar portion 34B extending out from, and angling
away from, the first portion 34A. The curvature profile may be
modified to meet any anatomical requirements.
[0042] Attachment member 34 preferably includes at least one, and
more preferably, a plurality of throughbores 42 located therein. In
this view, additional throughbores 42A and 42B are provided in the
curved portion 34A. The throughbores 42, 42A, and 42B provide a
number of functions, such as enabling fastening members such as a
surgical screw (not shown) to pass therethrough in order to allow
the fastening member 34 to be secured to at least a portion of a
surface of the ilium.
[0043] Attachment member 36 is also shown as being substantially
rectangularly shaped; however, it is envisioned that the shape may
be altered to other configurations. It will be noted that
attachment member 36 also has two distinct portions, i.e., a first
substantially curved portion 36A originating from, and contiguous
with, the inner surface 16 of the acetabular cup 12, and a second
substantially planar portion 36B extending out from, and angling
away from, the first portion 36A. Again, the curvature profile may
be modified to meet any anatomical requirements.
[0044] Attachment member 36 preferably includes at least one, and
more preferably, a plurality of throughbores 44 located therein. In
this view, an additional throughbore 44A is provided in the curved
portion 36A. The throughbores 44 and 44A provide a number of
functions, such as enabling fastening members such as a surgical
screw (not shown) to pass therethrough in order to allow the
fastening member 36 to be secured to at least another portion of a
surface of the ilium spaced away from attachment member 34.
[0045] The installation of the acetabular prosthesis 10 would be
accomplished in any number of ways, as are currently known in the
art. The surgeon would surgically prepare the acetabulum and
surrounding pelvic area to receive the acetabular prosthesis 10.
This preparation would typically include removing any debris (e.g.,
bone fragments, bone cement) from the acetabulum. The surgeon would
then install an allograft, if necessary, and install bone cement,
if necessary, into the acetabulum. The acetabular cup 12 would then
be received into, and anatomically aligned with, the acetabulum. At
least one fastening member, such as a surgical screw, would then be
placed through one of the throughbores 26 and into the interior of
acetabulum, thus securing the acetabular cup 12 to the acetabulum.
The attachment members 32, 34, and 36 would then be secured to the
ischium and ilium, respectively, with fastening members, such as
surgical screws.
[0046] However, if the acetabulum and/or the surrounding pelvic
structures have any significant defects present, the loading will
be borne primarily by the allograft and/or bone cement material, as
previously described. Therefore, it is desirable to have the
surfaces of the acetabular prosthesis 10 actually abut against the
respective surfaces of the acetabulum and/or the surrounding pelvic
structures, as opposed to using allografts and bone cement to fill
the gap therebetween. Because the acetabular prosthesis 10 is
constructed of metallic material, it is much stronger than
allografts and bone cement, and therefore is much more able to
withstand the loads and forces associated with standing, walking,
and running activities.
[0047] Therefore, the present invention preferably employs at least
one augment or spacer member to compensate for the fact that the
acetabulum and/or the surrounding pelvic structures may have
defects therein which prevent the outer surface 18 of the
acetabular cup 12 from contacting the surface of the acetabulum,
and/or the outer surfaces 32C, 34C, and 36C, respectively, from
contacting the respective surfaces of the pelvis, i.e., the ischium
and the ilium.
[0048] The spacer members are preferably constructed from any
suitable biocompatible material, such as titanium, stainless steel,
titanium alloy, cobalt-chrome-molybdenum alloy, etc. and is
preferably made of the titanium alloy Ti-6Al-4V.
[0049] Referring to FIGS. 6-9, several different types of
acetabular spacer members 60, 62, and 64 for use with the outer
surface 18 of the acetabular cup 12, according to the general
teachings of the present invention, are shown. It should be noted
that only one spacer member would generally be used at a time in
practice; however, multiple spacer members may be used in some
instances. For example, if there is a relatively small defect in
the superior region of the acetabulum, acetabular spacer member 60
can be employed. If there is a larger defect, either acetabular
spacer member 62 or 64 may be used. It is envisioned that either
smaller and/or larger acetabular spacer members may also be
employed with the present invention.
[0050] The acetabular spacer members 60, 62, and 64 are preferably
substantially curved so that the lower surfaces 60A, 60B, and 60C,
substantially conform to the curvature of the outer surface 18 of
the acetabular cup 12. Additionally, the acetabular spacer members
60, 62, and 64 preferably include an area defining a substantially
curved and raised appendage or ridge 66, 68, and 70 formed on the
lower surface 60A, 60B, and 60C, respectively, thereof for mating,
and more preferably, sliding engagement with the groove 20.
Finally, each acetabular spacer member 60, 62, and 64 preferably
has at least one throughbore 72. The throughbores 72 preferably
include a threaded surface 74 thereon. It should be noted that the
raised ridges 66, 68, and 70 are bisected by the respective
throughbore 72.
[0051] The purpose of the raised ridges 66, 68, and 70,
respectively, is to allow the respective acetabular spacer member
60, 62, or 64 to slidingly mate with the groove 20 on the outer
surface 18 of the acetabular cup 12. This allows the surgeon the
option of positioning the respective acetabular spacer member 60,
62, or 64 practically anywhere along the length of the groove 20 to
best deal with the particular acetabular defect in the
superior-posterior region. For example, the acetabular spacer
member 60, 62, or 64 can slide in a superior-posterior direction
with respect to the acetabulum. It is also envisioned that the
acetabular spacer member 60, 62, or 64 can slide in a medial
direction, as well. Once the final position of the acetabular
spacer member is determined, the surgeon can then secure the
respective acetabular spacer member to the acetabular cup 12 by
inserting a fastening member, such as a surgical screw, through one
or more available throughbores 72 which preferably aligns with one
or more of the throughbores 26 which bisect the groove 20. The
screw would preferably extend upwardly through the acetabular cup
12 and into the respective acetabular spacer member, with the screw
tip not extending past the upper surface of the respective
acetabular spacer member. The modified acetabular prosthesis 10 can
then be installed in the acetabulum, as previously described, such
that the acetabular spacer member 60, 62, or 64 is disposed between
the outer surface 18 of the acetabular cup 12 and the
acetabulum.
[0052] Unfortunately, the use of acetabular spacer members 60, 62,
or 64 alone is sometimes not enough to address each and every
particular clinical situation. The use of the acetabular spacer
members 60, 62, or 64 may address the defect in the acetabulum, but
it may not address a defect in the surrounding pelvic structures,
or alternatively, the use of the acetabular spacer members 60, 62,
or 64 may alter the attachment point of the attachment members 32,
34 or 36 such that an undesirable gap is created between the
respective outer surfaces 32C, 34C, and 36C and the pelvis.
[0053] Therefore, the present invention employs at least one other
augment or spacer member to compensate for the fact that the
surrounding pelvic structures may have defects therein which
prevent the outer surfaces 32C, 34C, and 36C of rigid attachment
members 32, 34, and 36, respectively, from contacting the
respective surfaces of the pelvis, i.e., the ischium and the
ilium.
[0054] Referring to FIGS. 10-12, two different types of attachment
spacer members 100 and 102 for use with the attachment members 32,
34, and 36, respectively, according to the general teachings of the
present invention, are shown. It should be noted that more than one
attachment spacer member can be used at one time in practice. For
example, if there is a relatively small defect in the surface of
the ischium, or attachment member 32 can not abut it, an attachment
spacer member 100 or 102 can be employed. If there is a defect in
the surface of the ilium (either anterior and/or posterior), or
attachment member 34 or 36 can not abut it, an attachment spacer
member 100 or 102 can be employed. It is envisioned that either
smaller and/or larger attachment spacer members may also be
employed with the present invention.
[0055] The attachment spacer members 100 and 102 preferably have at
least one flat surface 100A and 102A, respectively, for mating
adjacently against the planar portions 32B, 34B, and 36B of
attachment members 32, 34, and 36, respectively. The other surface
of the attachment spacer members 100 and 102 may be either flat and
parallel 100B or flat and non-parallel (i.e., inclined) 102B.
[0056] Each attachment spacer member 100 and 102 preferably has at
least one throughbore 104. At least one of the throughbores 104
preferably include a threaded surface 106 thereon. The surgeon can
then secure the respective attachment spacer member 100 or 102 to
the outer surface 32C, 34C, or 36C, respectively, by inserting a
fastening member, such as a surgical screw, through one or more
available throughbores 104 which preferably aligns with one or more
of the throughbores 40, 42, 44, respectively, in planar portions
32B, 34B, or 36B, respectively. The further modified acetabular
prosthesis 10 then can be installed in the acetabulum, as
previously described, such that the attachment spacer members 100
and/or 102 are disposed between the outer surface 32C, 34C, or 36C,
respectively, of the planar portions 32B, 34B, or 36B,
respectively, of the attachment members 32, 34, or 36,
respectively, and the pelvis, i.e., the ischium and/or the ilium.
Preferably, two diagonally opposed and spaced throughbores 104 are
used to attach the attachment spacer member 100 and 102 to the
outer surface 32C, 34C, or 36C, respectively, of the planar
portions 32B, 34B, or 36B, respectively, of the attachment members
32, 34, or 36, respectively, and the pelvis, i.e., the ischium
and/or the ilium. Bone screws (not shown) can then be inserted
through the two diagonally opposed throughbores 104, and the
aligned one or more of the throughbores 40, 42, 44, respectively,
to secure the attachment members 32, 34, or 36, respectively, to
the pelvis.
[0057] It should be noted that sometimes it is only necessary to
use the attachment spacer members 100 and/or 102 alone, instead of
using them in conjunction with an acetabular spacer member 60, 62,
or 64. In that scenario, it is beneficial that the groove 20 is
employed in the outer surface 18 of the acetabular cup 12, as
opposed to a raised appendage or ridge which may interfere with the
proper alignment of the acetabular cup 12, or might irritate the
acetabulum.
[0058] The foregoing description is considered illustrative only of
the principles of the invention. Furthermore, because numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
construction and process shown as described above. Accordingly, all
suitable modifications and equivalents that may be resorted to that
fall within the scope of the invention as defined by the claims
that follow.
* * * * *