ACETABULAR ROOF REINFORCEMENT PLATE
Inventors: Johann FIERLBECK, Alfred NIEDERBERGER and Herbert RESCH
Priority Claim
[0001] The present application claims priority to U.S. Provisional Application Serial No.
61/473,983 filed on April 11, 201 1 and entitled "Acetabular Roof Reinforcement Plate," the
entire disclosure of which is incorporated herein by reference.
Field of the Invention
[0002] The present invention relates to a device for treating a bone and, in particular, relates to
an implant for fixing the acetabulum of a hip joint.
Background
[0003] Fractures of the acetabulum often require surgical reconstruction using screws and
plates to stabilize the fracture. In the field of revision hip replacement the acetabulum may be
reinforced using an acetabular implant including a hemispherical basket with a plurality of
flanges extending therefrom. The flanges must be manually bent to adjust the fit to the anatomy
of the patient. Screws are inserted through holes in the flanges and the hemispherical basket in a
non-angularly stable configuration to fix the acetabular implant to the bone. However, these
osteosyntheses are generally unable to secure the fracture sufficiently to allow immediate weight
bearing. Thus, the fractured acetabulum is often fixed in a first surgical procedure after which the
patient is not allowed to place weight on the affected side of the pelvis for at least six weeks.
During this time the patient is confined to the bed. After six weeks, an artificial hip may be
implanted in a second surgical procedure after which weight may be placed on the joint.
However, the pain and reduced mobility associated with these separate procedures have a
significant negative impact on the health of patients who are often elderly. Among other
problems, prolonged periods of immobility may negatively impact muscle volume, blood
circulation and bone volume.
Summary of the Invention
[0004] The present invention is directed to an acetabular implant, comprising a body including
a substantially convex exterior surface configured to be received within and engage an
acetabulum and a substantially concave interior surface sized and shaped to receive a head
portion of a femur along with a rim extending about a periphery of the body and including a
plurality of first holes, each of the first holes being configured to lockingly receive a bone
fixation element therethrough in an angularly stable configuration and a flange extending radially
from the rim and including a plurality of second holes, each of the second holes being configured
to receive a bone fixation element therethrough in an angularly stable configuration.
Brief Description of the Drawings
[0005] Fig. 1 shows a perspective view of an implant according to an exemplary embodiment
of the present invention;
Fig. 2 shows another perspective view of the implant of Fig. 1; and
Fig. 3 shows a schematic drawing of the implant of Fig. .
Detailed Description
[0006] The present invention may be further understood with reference to the following
description and the appended drawings, wherein like elements are referred to with the same
reference numerals. The present invention relates to a device for treating a bone and, in
particular, relates to an implant for fixing the acetabulum of a hip joint. Exemplary embodiments
of the present invention describe an acetabular implant configured to receive angularly stable
bone fixation elements such that fractured portions of the acetabulum are securely fixed and
immediate weight bearing thereon is possible.
[0007] As shown in Figs. 1 - 3, an implant 100 according to an exemplary embodiment of the
present invention comprises a body 102 and a flange 104 extending therefrom. The implant 100
according to this embodiment is configured to fix fractures of the acetabulum in a hip joint
replacement and the body 102 is sized and shaped to engage the acetabulum while the flange 104
extends therefrom to engage the gluteal surface of the ilium (facies glutea). The implant 100 may
be formed of a biocompatible metal such as, for example, titanium or stainless steel. It will be
understood by those of skill in the art, however, that the implant 100 may be formed of any of a
variety of biocompatible materials so long as the material possesses the required strength. In
particular, the body 102 includes a substantially convex exterior surface 106 for engaging the
acetabulum and a substantially concave interior surface 108 sized and shaped to receive a
femoral head prosthesis. The substantially concave interior surface 108 may also be configured
for attachment to an acetabular cup including a smooth surface for interfacing with the femoral
head prosthesis during articulation. The implant 100 includes a rim 116 extending about at least
a portion of a perimeter of the body 102 sized and shaped to engage an edge of the acetabulum.
A plurality of bone fixation element receiving holes 118, 1 0, each configured to receive a bone
fixation element 1 2 in an angularly stable configuration, are distributed in the flange 104 and
the rim 16. The angularly stable connections between the bone fixation elements and the
implant 100 permits immediate weight bearing so that the acetabular- cup and/or the hip
prosthesis (e.g., artificial femur head) may be implanted in a single procedure during which the
implant 100 is also implanted.
[0008] The body 102 according to this embodiment is partially hemispherical and includes an
opening 10 extending therethrough along a central axis of the body 102. As would be
understood by those skilled in the art, bodies 102 may be provided in a variety of sizes to
accommodate anatomical differences from patient to patient. For example, the body 102 may
have an inner radius ranging from between 35 mm to 60 mm. The body 102 includes a first
elongated compression hole 112 extending therethrough from the interior surface 108 to the
exterior surface 106. The first compression hole 2 extends through a portion of the body 102
such that a shaft of a bone fixation element inserted therethrough extends through the acetabulum
and into the pubis portion of the pelvis. The body 102 may also include a second elongated
compression hole 114 extending therethrough from the interior surface 108 to the exterior surface
106 such that a shaft of a bone fixation element inserted therethrough may extend through the
acetabulum into the ischium bone. Each of the compression holes 112, 114 includes a sloped,
concave engagement surface 126 for engaging a spherical head of a bone fixation element 124.
As would be understood by those skilled in the art, the spherical heads of bone fixation elements
interface with the sloped surfaces 1 6 of the first and/or second compression holes 11 , 114 to
apply compression across a fracture. The partially hemispherical body 102 may have a radius
selected to be slightly smaller than a radius of the acetabulum to facilitate compression of the
fractured portions. In this embodiment, the first and second compression holes 112, 14, the
body 102 are the only bone fixation element receiving holes formed in the body 102.
[0009] The rim 116 extends about at least a portion of a perimeter of the body 102 and is
shaped to engage an edge or rim of the acetabulum. For example, the rim 116 may be curved,
extending laterally from an edge of the body 102. The rim 116 includes a plurality of bone
fixation element receiving holes 118. In this embodiment each of the bone fixation element
receiving holes 11 is configured to receive a bone fixation element therethrough in an angularly
stable configuration along an axis thereof. However as would be understood by those skilled in
the art, one or more of these holes 11 may be a variable angle hole permitting a user to mount a
bone fixation element therethrough at a user selected angle relative to an axis of the hole 118.
The axes of one or more of the bone fixation element receiving holes 11 may be angled with
respect to an axis perpendicular to a bone contacting surface 128 adjacent the hole 118 such that
a bone fixation element 122 inserted therethrough is angled with respect to the perpendicular
axis. Several factors may determine the angle of the axes of the bone fixation element receiving
holes 1 8 with respect to the perpendicular axis. For example, angles of the axes of the bone
fixation element receiving holes should be selected such that the bone fixation element 122
inserted therein engages as much volume as possible in the thin bone while facilitating insertion
through an existing surgical access path (e.g, the incision through which the implant was
inserted). Those skilled in the art will understand that, although a surgical incision may extend
along a surgical axis, surgical tools (e.g., drills, sleeves) and other items may be inserted
therethrough angled relative to the surgical axis. Bone fixation elements 122 may thus be
inserted into the holes 11 at any angle relative to the surgical access axis permitted by the
surrounding tissue. In addition, angles of each of the axes may vary from one another for optimal
anchorage in the bone. The holes 118 may, for example, including threading along inner surfaces
thereof for lockingly engaging a threaded head of the bone fixation element 122 inserted
thereinto. Thus, once the bone fixation elements 122 have been inserted through the holes 118
and engaged therewith, the bone fixation elements 22 are immovable relative to the implant
100.
[0010] The flange 104 extends radially from the body 102 and is sized and shaped to engage
the gluteal surface of the ilium. In particular, the flange 104 may extend from a portion of the
rim 116. Similarly to the rim 116, the flange 104 includes a plurality of bone fixation element
receiving holes 120, each of which are configured to receive a bone fixation element 122
therethrough in an angularly stable configuration along an axis thereof. The angles of the axes of
the holes 120 may be selected similarly to the axes of the holes 1 8, permitting bone fixation
elements 122 to be inserted therethrough via the surgical site while providing optimal anchorage
in the bone. The plurality of bone fixation element receiving holes 120 may include a threading
extending along an inner surface thereof for engaging a threaded head of the bone fixation
elements 122. Thus, similarly to the bone fixation element receiving holes 120 in the rim 116,
once the bone fixation elements 122 are inserted into and engaged with the holes 120, the bone
fixation elements 122 are immovable with respect to the implant 100.
[0011] As described above, the implant 100 is configured to treat fractures of the acetabulum.
According to an exemplary surgical technique using the implant 100, the body 102 is positioned
in the acetabulum with an exterior convex surface 106 thereof contacting the acetabulum while
the flange 104 is positioned along the iliac of the pelvis. The rim 116 is positioned around an
edge of the acetabulum. Bone fixation elements 122 (e.g., bone screws) are inserted through the
bone fixation element receiving holes 1 along the rim 16 and the bone fixation element
receiving openings 120 along the flange in an angularly stable configuration along axes thereof.
Bone fixation elements 124 may also be inserted through the first and/or second compression
holes 112, 114 to provide compression to the fractured portions of the bone as would be
understood by those skilled in the art.
[0012] As described above, the angularly stable fixation of the implant via the bone fixation
elements 122 provides sufficient strength of connection between the pelvis and the implant 100
that immediate weight bearing is possible. Thus, the patient is not required to wait six weeks for
a follow-up procedure in which a hip replacement is to be performed. Rather, the acetabular cup
and the prosthetic femur head may be implanted during the same surgical procedure. Once the
implant 100 has been fixed to the pelvis, as desired, the acetabular cup may be attached to the
interior surface 108 and a prosthetic femoral head may then be attached to the femur. The
prosthetic femoral head and the acetabular cup are then able to interface with one another,
providing articulation of the hip joint.
[0013] It will be apparent to those skilled in the art that various modifications and variations
can be made in the structure and the methodology of the present invention, without departing
from the spirit or scope of the invention. Thus, it is intended that the present invention cover the
modifications and variations of this invention provided that they come within the scope of the
appended claims and their equivalents.
What is claimed is:
1. An acetabular implant, comprising:
a body including a substantially convex exterior surface configured to be
received within and engage an acetabulum and a substantially concave interior
surface sized and shaped to receive a head portion of a femur;
a rim extending about a periphery of the body and including a plurality of
first holes, each of the first holes being configured to lockingly receive a bone
fixation element therethrough in an angularly stable configuration; and
a flange extending radially from the rim and including a plurality of
second holes, each of the second holes being configured to receive a bone fixation
element therethrough in an angularly stable configuration.
2. The implant of claim , further comprising an opening extending through the body along
a central axis thereof.
3. The implant of claim 1, further comprising a first compression hole extending through the
body, the first compression hole being elongated and including a sloped surface therein
configured to engage a spherical head of a bone fixation element.
4. The implant of claim 3, further comprising a second compression hole extending through
the body, the second compression hole being elongated and including a sloped surface
therein configured to engage a spherical head of a bone fixation element.
5. The implant of claim 1, wherein the plurality of first holes include a threading along an
inner surface thereof configured to engage a threaded head of a bone fixation element.
6 . The implant of claim , wherein the plurality of second holes include a threading along an
inner surface thereof configured to engage a threaded head of a bone fixation element.
7. The implant of claim 1, further comprising a variable angle hole extending through the
rim, the variable angle hole configured to receive a bone fixation element therethrough at
a user selected angle within a permitted range of angulation relative to a central axis
thereof.
8 . The implant of claim 1, wherein the flange is configured to engage an ilium portion of a
pelvis.
9. An implant for treating a pelvis, comprising:
a cup-shaped body including a convex exterior surface configured to
engage an acetabulum and a concave interior surface sized and shaped to receive
one of a femoral head and a femoral head implant;
a rim extending about at least a portion of a periphery of the cup-shaped
body, the rim being configured to engage a portion of bone surrounding an
acetabulum into which the cup-shaped body is inserted and including a plurality of
first holes extending therethrough, each of the first holes being configured to
lockingly receive a bone fixation element therethrough in an angularly stable
configuration; and
a flange extending radially outward from the rim to engage an ilium
portion of a pelvis to which the implant is to be mounted, the flange including a
plurality of second holes extending therethrough, each of the second holes being
configured to lockingly receive a bone fixation element therethrough in an
angularly stable configuration.
10. The implant of claim 9, further comprising a first opening defined by a portion of the cupshaped
body adjacent to the rim through which the one of a femoral head and a femoral
head implant is inserted, and a second opening extending through a portion of the body
opposite the first opening.
11. The implant of claim 9, further comprising a first compression hole extending through the
body, the first compression hole being elongated and including a sloped surface therein
configured to slidingly engage a head of a bone fixation element inserted therethrough to
apply compression across a fracture of the acetabulum.
1 . The implant of claim 1 , further comprising a second compression hole extending
through the body, the second compression hole being elongated and including a sloped
surface therein configured to slidingly engage a head of a bone fixation element inserted
therethrough to apply compression across a fracture of the acetabulum.
1 . The implant of claim 9, wherein each of the first holes includes threading along an inner
surface thereof configured to engage a threaded head of a bone fixation element inserted
therein.
14. The implant of claim 9, wherein each of the second holes includes threading along an
inner surface thereof configured to engage a threaded head of a bone fixation element
inserted therein.
15. The implant of claim 9, further comprising a variable angle hole configured to receive a
bone fixation element therethrough at a user selected angle within a permitted range of
angulation relative to a central axis thereof.
16. The implant of claim 9, wherein the flange is configured to engage a fades glutea.
17. A method for treating a hip joint, comprising:
positioning an implant along a pelvis such that a body of the implant is within an
acetabulum and a flange of the implant extends along an ilium portion, the body including
a substantially convex exterior surface engaging a surface of the acetabulum and a
substantially concave interior surface sized and shaped to receive a head portion of a
femur, a rim extending about a periphery of the body over an edge of the acetabulum and
including a plurality of first holes, the flange extending radially from the body and
including a plurality of second holes; and
inserting bone fixation elements through the first and second holes, each in an
angularly stable configuration.
18. The method of claim 15, wherein an opening extends through the body along a central
axis thereof.
19. The method of claim 17, further comprising inserting a second bone fixation element
through an elongated first compression hole extending through the body, a spherical head
of the second bone fixation element engaging a sloped surface of the first compression
hole.
20. The method of claim 19, further comprising inserting a third bone fixation element
through a second elongated compression hole extending through the body, a spherical
head of the third bone fixation element engaging a sloped surface of the second
compression hole.