Invention (Patent): Dennis DA, Komistek RD. Method and apparatus for hip prosthesis US5951605 (1999).
US5951605A United States
Inventors: Douglas A. Dennis, Richard D. Komistek
Current Assignee: Rose Biomedical Res
Worldwide applications 1996 US 1997 EP WO CA
Application US08/672,994 events:
1996-07-01 Application filed by Rose Biomedical Res
1996-07-01 Priority to US08/672,994
1996-09-19 Assigned to ROSE BIOMEDICAL RESEARCH
1997-06-05 Priority to PCT/US1997/010170
1997-06-05 Priority to CA002262407A
1997-06-05 Priority to EP97929949A
1999-09-14 Application granted
1999-09-14 Publication of US5951605A
2016-07-01 Anticipated expiration
Status: Expired - Fee Related
Method and apparatus for hip prosthesis
Douglas A. Dennis, Richard
D. Komistek
Abstract
An
prosthesis for allowing natural ball and socket type movement, as in a hip or
shoulder. A femoral component having a ball at one extremity is engaged with an
acetabular component having a hemispherical cup to receive the ball. A
ligamentous material extends from a port in the hemispherical cup to a port in
the ball to apply a resistive force to resist any dislocating force, the
resistive force varying in proportion to the movement of the femoral component
from a natural and relaxed position in relation to the acetabular component.
Description
FIELD OF THE INVENTION
The present invention
relates to a prosthesis, and more particularly to an apparatus and method for
engaging the femoral component of a hip prothesis with the acetabular component
of the hip prosthesis utilizing a ligamentous attachment extending from the
femur through a hole in the femoral stem and femoral head and through the cup
of the acetabular component to the acetabulum.
BACKGROUND OF THE INVENTION
Artificial hip and
shoulder ball joints conventionally employ ball and socket articulation
components. In a hip prosthesis, the acetabular portion is embedded in the bony
structure of the acetabulum and the femoral portion is embedded in the femur.
The femoral portion normally includes the ball while the acetabular portion
normally includes the socket or cup. The ball is attached to an arm composed of
a neck which in turn is attached to a stem or shaft.
It has been found
in use that a dislocating force is created when the neck of the arm attached to
the ball impinges on the rim of the acetabular component. Because of the leverage
associated with the patient's femur, the dislocating force produced when the
neck contacts the rim of the bearing can be considerable. For example, a force
applied to a patient's leg can produce a dislocating force of several fold
because of the leverages involved. Unfortunately, as is apparent from the
geometry of the situation, the more the socket bearing encompasses the ball,
the greater the restraining force on the ball, but at the same time the less
the range of motion prior to the neck impinging upon the edge of the bearing to
create undesired leverage.
A number of methods
are known for retaining the ball in the cup. In the most common method, the
patient's own anatomy, i.e., his or her muscles, tendons and ligaments, are
used to retain the ball within the socket. A hemispherical cup typically is
used which allows the ball and its attached neck the maximum amount of movement
without contact of the neck with the edge of the cup. The surgeon when
installing such a prosthesis aligns the ball and cup as closely as possible
with the patient's natural anatomy so that the patient's movements do not tend
to dislocate the ball from the cup. Such precise alignment is easiest the first
time the prosthesis is implanted in a patient. Subsequent reconstructions are
much more difficult to align because of deterioration of the anatomy as a
result of the first operation, the healing process after the operation, the
incompetency of soft tissue, and changes in the anatomy caused by the presence
of the prosthesis itself.
Notwithstanding the
various retaining systems attempted in the prior art, a significant number of
prostheses dislocate. Such dislocations immobilize the patient, can be painful,
and can necessitate the discomfort and expense of a second operation. As discussed
above, the critical alignment is even more difficult to achieve and maintain
when a second implantation is performed. Accordingly, even higher dislocation
frequencies are encountered for second and subsequent implantations.
An alternative to
the semi-constrained construction is a construction wherein the cup is
physically constrained. In this construction, a spherically-shaped bearing
surrounds the ball and serves as the cup. The bearing is attached to a fixation
element which is embedded in, for example, the patient's pelvic bone. The
bearing encompasses more than one-half of the ball surface and thus constrains
the ball and its attached arm from dislocation. For plastic bearings, the ball
and bearing are usually assembled by forcing the bearing over the ball. The
more of the ball which is encompassed by the bearing, the greater the required
assembly force, and the greater the constraining force to prevent postoperative
dislocation of the joint. In addition, the more that the bearing encompasses
the ball, the smaller the range of motion for the ball prior to contact of the
bearing with the arm attached to the ball. An example of a constrained
artificial joint employing a plastic bearing is shown in U.S. Pat. No.
3,996,625 by Noiles.
A constrained
construction using a metal socket bearing is shown in U.S. Reissue Pat. No.
28,895 by Noiles. In a practical sense, the metal bearing of Noiles can be said
to be non-dislocatable, since the force required to extract the metal sphere
from the enclosing metal socket bearing is at least several thousand pounds.
Accordingly, in use, rather than the metal ball dislocating from the metal
socket bearing, a high dislocating force will cause the fixation element to be
disrupted from the bone in which it has been embedded. Metal balls in metal
socket bearings are used in only a minority of joint reconstructions.
Another type of
artificial ball and socket joint, referred to as an endoprosthesis, eliminates
the fixation element associated with the socket and simply uses a ball
surrounded by a plastic socket bearing in a spherical metal head, which head is
placed in the patient's natural socket but not secured to bone. For this
construction, the ball can rotate within the bearing up to the rim of the
bearing (the bearing is greater than a hemisphere so as to be retained on the
ball), and then the bearing and its attached head rotate in the patient's
socket. As with certain other constructions, anatomical alignment is used to
avoid dislocations, in this case between the metal head and the natural socket.
A device which is
adaptable to employ several different constraining systems is shown in U.S.
Pat. No. 4,960,427 by Noiles. Examples of other prostheses are disclosed in
U.S. Pat. Nos. 5,314,489 by Hoffman, U.S. Pat. No. 5,201,767 by Caldanse, U.S.
Pat. No. 4,778,473 by Mathews, U.S. Pat. No. 5,108,445 by Ashby, U.S. Pat. No.
5,370,704 by DeCarlo and U.S. Pat. No. 5,413,610 by Amino.
SUMMARY OF THE INVENTION
The present
invention is an apparatus and method for constraining the ball component and
the cup component of a prosthesis. Although the description below is set forth
in the context of a hip prosthesis, it will be apparent that the invention is
equally applicable to a shoulder prosthesis or any other prosthesis imitative
of a ball and socket joint.
The prosthesis of
the invention includes a ball which constitutes the femoral head of the femoral
component, a femoral neck which is securely attached to the ball either by
integral fabrication with the ball or by attachment means, and a femoral stem
extending from the neck for implantation within the medullary canal of the
femur. The stem preferably includes tissue in-growth surfaces for bone tissue
in-growth to facilitate secure attachment of the femoral component of the
prosthesis to the femur. The attachment of the femoral component to the femur
may or may not utilize cement.
The ball includes a
port extending from the interior of the ball through the wall of the ball to
the exterior surface of the extreme of the femoral head. Through the port is
threaded a natural or artificial ligamentous material such as teflon,
polyester, polyethylene, Gortex or other material. It may be autogenous,
homologous, xenographic or synthetic, or any combination thereof. The
ligamentous material continues from the ball interior through the femoral neck
and out a second port in the upper portion of the femoral stem opposite the
femoral ball and neck. The femoral end of the ligamentous material can be tied
off or otherwise secured on or outside the femoral stem or on the femur itself.
Alternatively, the ligamentous material may be fixed at one end in the ball
interior.
The cup in the
acetabulum component is of a conventional biocompatible cup material used for
ball and socket prostheses, such as polyethylene or polished cobalt chromium,
and is implanted in the bony structure of the acetabulum of the patient in the
conventional manner. The cup includes a cup port to receive the acetabulum end
of the ligamentous material, which is threaded through the cup port and tied
off or otherwise attached to the exterior surface of the acetabular component
or to the bony structure of the acetabulum. The acetabular component is secured
to the bony structure of the acetabulum of the patient in the conventional
manner utilizing an appropriate combination of cement, fasteners and in-growth
surfaces.
The ligamentous
material thus extends from the acetabular end which is attached to the
acetabulum, through the cup port, through the ball of the femoral head and
through the femoral neck interior, and out the femoral stem port where it is
tied off or secured to the femur. In a preferred embodiment the port in the
femoral ball or the port in the acetabulum cup or both are chamfered on the end
which meets the opposite joint component. The chamfering allows the ball to
move within the cup without binding the ligamentous material between the ball and
cup.
The ligamentous
material thus attaches the femur component to the acetabulum. The attachment
can be varied from a secure attachment in which there is tension in the
ligamentous material in order to maintain close alignment of the ball in the
cup while permitting normal universal ball and socket type movement, to a loose
attachment in which there is a desired amount of "play" in the
ligamentous material in order to allow normal universal ball and socket type
movement as well as limited movement of the ball into and out of the cup. The
two ends of the ligamentous material can be secured, and the degree of
attachment of the femoral component to the acetabular component can therefore
be established, either prior to or during the implantation procedure.
In an alternative
embodiment, the ligamentous material is wholly on the outer surfaces of the
femoral component and acetabular component. The ligamentous material thus
includes a femoral end which attaches to the femur and an acetabular end which
attaches to the acetabulum. The ligamentous material may comprise a single
element or multiple elements arranged in a mesh or other desired configuration.
The play in the
ligamentous material, and similarly the pathways for the ligamentous material,
can be chosen based on a variety of factors such as patient lifestyle and
physiology.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an
elevation view of the preferred embodiment of the invention.
FIG. 2 is a side
sectional view of a portion of the invention, shown with the femoral component
engaged with the acetabulum component by the ligament.
FIG. 3 is a side
sectional view of a portion of the invention, shown with the femoral component
shifted with respect to the acetabulum component.
FIG. 4 is an
elevation view of an alternative embodiment of the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
An elevation view
of a preferred embodiment of the invention 10 is depicted in FIG. 1
in which the bone structure of the patient is shown in phantom. A femoral
component 20 includes a ball 22 at the femoral extreme, the ball
being in the shape of a partial sphere or a hemisphere. The ball is attached to
or formed integrally with a neck portion 24 of the femoral
component 20, which in turn is attached to or formed integrally with
a stem portion 26 of the femoral component 20.
The femoral
component 20 is of an overall shape and size that is typical in the field
of hip prostheses. In-growth texturing is on the surface of portions of
the femoral component 20, illustrative texturing 28 being shown in
FIG. 1. The femoral component 20 may or may not be attached to the
femur with cement. The femoral component 20 is fabricated in the
well-known manner from forged stainless steel or other durable biocompatible
material such as titanium or cobalt alloys or alumina or zirconia ceramics. The
normal size, shape, material and manufacture of the femoral component of hip
prostheses are generally known in the art, and are not further described
herein.
The femoral
component 20 of the present invention 10 differs from those of
the prior art in that a ligament port 30 extends from the femoral
component extreme at the ball 22 surface, through the femoral
neck 24, and to the surface of femoral stem 26. The preferred
embodiment shown in FIG. 1 shows the ligament port 30 as
substantially straight, extending radially from the ball 22 surface,
through the ball 22 center. However, the ligament port 30
may assume other directions as well, so long as the ball end 32 of the ligament
port 30 meets the ball 22 surface. The port could therefore be
blind, or could exit through the femoral neck 24, or a portion of
the ball 22 that does not engage the cup, or through some other
location on the femoral stem 26. Of course, a straight port 30
is easier to produce, because it can be made with a single drilling operation
rather than involving casting or multiple drilling or complex machining
operations.
The acetabular
component 60 of the invention 10 includes a cup 62
having a hemispherical receptacle 64 to receive the ball 32
of the femoral component 20. The cavity of the hemispherical
receptacle 64 of the acetabular component 60 is thus
substantially the same size as or slightly larger than the ball 22 of
the femoral component 20. The exterior surface 66 of
the cup 62 generally defines a hemisphere larger than
the hemispherical receptacle 64, so that the hemispherical
receptacle 64 and the hemispherical exterior surface 66 define a cup wall
68 therebetween.
The cup 62
is of a size and overall configuration that is generally utilized in the art.
It is preferably fabricated from a biocompatible material having a low
coefficient of friction, such as polyethylene or other polymers or composites
of the same, in order to allow smooth sliding between the hemispherical
receptacle 64 of the acetabular component 60 and
the ball 22 of the femoral component 20.
The cup 62
includes an acetabular component ligament port 70 extending from
the hemispherical receptacle 64 through the cup wall 68 to the
exterior surface 66. As in the case of the femoral component ligament
port 30, the acetabular component ligament port 70 is shown
straight and through the cup wall 68 in the preferred embodiment of FIG. 1, but
could be in some other design as well such as a blind hole or a non-linear hole
so long as there is an opening to the hemispherical receptacle 64.
A ligament 80
extends from the exterior surface 66 of the cup 62 through the
acetabular component ligament port 70 and into the hemispherical
receptacle 64. From there, the ligament extends through the femoral
component 20 ball 22, the femoral neck 24
and femoral stem 26, via the femoral component ligament
port 30. A free end 82 of the ligament 80 extends out
the femoral component ligament port 30 adjacent the femoral
stem 26.
As shown in FIG. 2,
the acetabular end 84 of the ligament 80 is secured to the
acetabulum via a fastener 88. The fastener 88 may be any
device capable of attaching to the acetabulum such as a screw or an element
capable of being cemented to the bony structure. The femoral end 82
of the ligamentous material 80 extends through a hole drilled in the
femur and attaches to the femur. As in the case of the acetabular
end 84 of the ligamentous material, the attachment is accomplished with
a fastener 90 or other suitable means. Alternatively,
the femoral end 82 of the ligament 80 could be attached to
the femoral component 20 of the prosthesis, and the acetabular
end 84 of the ligament 80 could be attached to
the acetabular component 60 of the prosthesis, but such an
arrangement allows tension on the ligament to urge the prosthesis components
apart from the bony structure.
The ligament 20
may be of any biocompatible ligamentous material of sufficient strength and
durability. In a preferred embodiment, the ligament 70 is polyester,
Gortex or teflon.
Each of
the ligament ports 30 and 70 are preferably chamfered in the manner
shown in FIG. 1, on the ends opening to the opposite joint component. Thus
the end 32 of the femoral component ligament port 30 which
opens to the acetabulum 60 is chamfered. Similarly,
the end 78 of the acetabular component ligament port 70
which opens to the femoral component 20 is chamfered. The chamfering
facilitates the movement of the femoral ball 22 in
the acetabulum cup 62 without binding the ligament 80, in
the manner described below.
The
assembled femoral component 20 and acetabular component 60
are shown in the side sectional view of FIG. 2. The ball 22 of
the femoral component 20 is received by the hemispherical
receptacle 64 of the acetabulum component 60. (Although the
depictions of FIG. 2 and FIG. 3 show a gap between the ball 22 and
the hemispherical receptacle 64, such gap is only for clarifying the
drawings. It should be appreciated that the ball 22 in fact rests on
and in contact with the surface of the hemispherical receptacle 64.)
The femoral component 20 and acetabular component 60 are
held together, to ensure that the ball 22 and hemispherical
receptacle 64 remain engaged, by the ligament 80. The acetabular
end 84 of the ligament 80 is fastened to the fastener 88
which in turn is fastened to the acetabulum. The free end 82 of
the ligament 80 is formed into a knot or is otherwise secured in a
manner that fixes the length of the ligament 80. By fixing the length
of the ligament 80, the engagement between the ball 22 of
the femoral component 20 and the hemispherical
receptacle 64 of the acetabular component 60 is defined. A
relatively long ligament which includes significant "play" will
define a loose engagement; a shorter ligament with little or no play will
define a more secure engagement; and a ligament under tension will define an
even more secure engagement.
Another area for
adaptation of the prothesis of the present invention to accommodate the
specific needs of a patient relates to the positioning of the ligament
port 30. It can be appreciated that the particular physiology of a patient
my dictate a ligament port 80 position which urges the femoral
component 20 toward the acetabular component 60 in a direction other
than the particular direction depicted in the figures.
The present
invention thus allows for considerable choice by the physician in defining the
engagement between the femoral component 20 and acetabular
component 60 of the prostheses and thus the overall flexibility allowed by
the patient. In making this choice, the physician will likely consider the
patent's age, lifestyle, medical history a nd overall health among other
factors. The choice can be made prior to surgery, or can even be made in the
course of sfirgery to allow consideration of physiological factors discovered
at that time.
Another important
benefit of She invention involves the system by which universal ball and socket
type movement is allowed between the ball 22 of the femoral
component 20 and the hemispherical receptacle 64 of
the acetabulum component 60. FIG. 3 shows the femoral
component 20 shifted downwardly and inwardly in relation to
the acetabular component 60. Such a shift corresponds to the femur
moving inward in the patient, as occurs for example when the patient's legs are
crossed. It can be seen from FIG. 3 that this movement produces a
counterclockwise rotation of the ball 22 in the hemispherical
receptacle 64. This rotation shifts the surface of the ball 22
in relation to the surface of the hemispherical receptacle 64,
thereby shifting the end 32 of the femoral component ligament
port 30 in relation to the end 78 of the
acetabular component ligament port 70.
Because
the ports 30 and 70 are preferably larger in cross section than
the ligament 80, this shifting is accommodated without binding the
ligament between the ball 22 and the hemispherical
receptacle 64 by the ligament shifting to the port wall nearest the port
of the opposite component. Thus, as shown in FIG. 3, the ligament 80 shifts
to the wall of the end 32 of the femoral component port 30
that is nearest the acetabular port 70, and the ligament 80
shifts to the wall of the end 78 of the acetabular component
port 78 that is nearest the femoral port 30.
Additional movement
can be accommodated between the ball 22 of the femoral
component 20 in relation to the hemispherical receptacle 64 of
the acetabular component 60, without binding
the ligament 80 between the ball 22 and
the hemispherical receptacle 64, by chamfering the port ends 32 and
78 in the manner shown in FIG. 3. Such chamfering serves to enlarge the port
ends 32 and 78, thereby positioning a wall of each port end 32 and 78
closer to the port end of the opposite component. Thus, the chamfering of
the end 32 of the femoral component port 30 positions a wall
of that end 32 closer to the acetabular component port 70
upon rotation of the ball 22 within the hemispherical
receptacle 64. Similarly, the chamfering of the end 78 of
the acetabular component port 70 positions a wall of
that end 78 closer to the femoral component port 30 upon
rotation of the ball 22 within the hemispherical
receptacle 64. By effectively positioning the wall of each port end closer
to the port of the opposite component through the chamfer, the ball 22
can rotate further in relation to the hemispherical receptacle 64
without binding the ligament 80 between the two.
An additional
advantage to the system of the present invention for maintaining engagement of
the femoral component 20 with the acetabular component 60,
is that the engagement force steadily increases as the movement of
the femoral component 20 in relation to the acetabular
component 60 increases. The engagement force is at its minimum when
the femoral component 20 and acetabular component 60 are in
a natural and relaxed position with perfect alignment between the femoral
component port 30 and the acetabular component port 70, as shown
in FIG. 2. Because the shortest distance between two points is a straight line,
this alignment results in the least tension on and maximum "play" in
the ligament 80. Rotation of the ball 22 in relation to the
hemispherical receptacle 64 (and this movement of the femoral
component 20 in relation to the acetabular component 60) is little
resisted by the ligament 80. In contrast, the engagement force is
greater when the femoral component 20 and acetabular
component 60 are in a position shifted from the natural and relaxed
position. As shown in FIG. 3, such a shift results in misalignment between
the femoral component port 30 and the acetabular component
port 70. This misalignment uses up the "play" in
the ligament 80, or even tensions the ligament 80 depending
on the degree of misalignment and the "play" in the ligament chosen
by the physician. The result is that further movement of the femoral
component 20 in relation to the acetabular component 60 to cause
further rotation of the ball 22 in relation to the hemispherical
component 64 in the direction of misalignment, is resisted by
the ligament 80. The resistive force increases as the extent of
movement increases, in a manner similar to the resistive force exerted by
natural ligaments or a natural joint. Such a system is superior to prior art
systems in which the resistive force is at a constant minimum over a wide range
of movement, and then abruptly changes to a maximum where the neck 24 (see FIG.
1) of the femoral component 20 impinges on the edge of
the cup 62 of the acetabular component 80. The system of
the present invention helps to dissipate dislocating forces before they can
rotate the ball 22 in relation to the hemispherical
receptacle 64 sufficiently to impinge the neck 24 of
the femoral component 20 on the edge of the cup 62 of
the acetabular component 60. At the same time, however, the system
allows ample flexibility when the femoral component 20 is in a
natural and relaxed position in relation to the acetabular
component 60.
The prostheses of
the invention is implanted in a manner similar to the methods known in the art.
An important departure in the surgical procedure, however, is the step of the
fixing the ligament 80 onto the femur and acetabulum. As discussed above,
this step can be performed prior to or during the surgery. The point is to fix
the ligament 80 length to define the engagement between
the femoral component 20 and the acetabular component 70.
In a preferred embodiment, this entails screwing a fastener 88 for attachment
to the acetabular end 84 of the ligament 80 into the bony
structure of the acetabulum; cementing or press fitting the acetabular
component 60 into place; drilling a hole through the femur; threading
the ligamentous material 80 through the femur hole; and attaching
the femur end 82 of the ligamentous material 80 to the
femur.
An alternative
embodiment of the present invention is depicted in FIG.4. The alternative
embodiment includes a femoral component 120 and acetabular
component 160. The femoral component includes a ball 122
attached to a neck 124 which joins a stem 126 in the manner
of the embodiment of FIGS. 1-3. The acetabular component 160 includes
a receptacle 164 to receive the ball 122 of the femoral
component 120. The femur is shown in FIG. 4, as is a portion of the acetabulum
bony structure.
The embodiment of
FIG. 4 utilizes a ligament 180 on the exterior of the prosthesis to
maintain engagement between the femoral component 120 and the acetabular
component 160. The femoral end 182 of the ligament 180
is attached to the femur by a fastener 196 or by other suitable
means, and the acetabular end 198 of the ligament 180 is
attached to the acetabulum by another fastener 199 or other suitable
attachment means.
It can be
appreciated that the apparatus of FIG. 4 ensures engagement of the femoral
component 120 with the acetabular component 160, because any
dislocating movement of the ball 122 of the femoral component 120
from the receptacle 164 of the acetabulum component 160 is
resisted by the ligament 180. Moreover, the greater the dislocating
movement, the greater the resistive force.
Although
a single ligament 180 is depicted in the embodiment of FIG. 4, the
invention encompasses the use of multiple ligaments as well. For example,
ligaments may be spaced around the joint whereby excessive rotation in any
direction is resisted by at least one ligament. Such an arrangement could
include a criss-crossing of the multiple ligaments or a web or networked
design, or a positioning of the ligaments in a manner calculated to resist
dislocating forces from particular directions.
We claim:
1. A hip prosthesis
for implantation into a natural acetabulum and natural femur of a patient,
comprising: a femoral component having a hemispherical portion and a femoral
component hole in the hemispherical portion; an acetabulum component having a
cup-shaped receptacle to receive the hemispherical portion to allow universal
movement between the femoral component and acetabulum component, the acetabulum
component having an acetabulum component hole in the cup-shaped receptacle; and
a ligamentous material extending through the femoral component hole and the
acetabulum component hole and adapted for attachment to at least the natural
acetabulum to maintain engagement between the femoral component and acetabulum
component.
2. The prosthesis
of claim 1, wherein said femoral component hole includes a femoral component
hole first port in the hemispherical portion and a femoral component hole
second port not in the hemispherical portion, the femoral component hole
extending from the femoral component hole first port to the femoral component
hole second port.
3. The prosthesis
of claim 2, wherein the femoral component hole is substantially straight.
4. The prosthesis
of claim 3, wherein the ligamentous material extends through said femoral
component hole and is engaged with femoral bone of the patient outside the
femoral component hole.
5. The prosthesis
of claim 2, wherein the acetabulum component hole includes an acetabulum
component hole first port in the cup-shaped receptacle and an acetabulum component
hole second port not in the cup-shaped receptacle, the acetabulum component
hold extending from the acetabulum component hole first port to the acetabulum
component hole second port.
6. The prosthesis
of claim 5, wherein the ligamentous material extends through said acetabulum
component hole and is engaged with acetabulum bone of the patient outside the
acetabulum component hole.
7. The prosthesis
of claim 1, wherein the femoral component hole includes a femoral component
hole end in the hemispherical portion through which the ligamentous material
extends, the femoral component hole end having a cross section larger than a
cross section of the ligamentous material to allow lateral movement of the
ligamentous material in the femoral component hole end.
8. The prosthesis
of claim 7, wherein the femoral component hole end is chamfered.
9. The prosthesis
of claim 1, wherein the acetabulum component hole includes an acetabulum
component hole end in the cup-shaped portion through which the ligamentous
material extends, the acetabulum component hole end having a cross section
larger than a cross section of the ligamentous material to allow lateral
movement of the ligamentous material in the acetabulum component hole end.
10. The prosthesis
of claim 9, wherein the femoral component hole includes a femoral component
hole end in the hemispherical portion through which the ligamentous material
extends, the femoral component hole end having a cross section larger than a
cross section of the ligamentous material to allow lateral movement of the
ligamentous material in the femoral component hole end.
11. The prosthesis
of claim 10, wherein at least one of the acetabulum component hole end and
acetabulum component hole end is chamfered.
12. A hip
prosthesis for implantation into an acetabulum and femur of a patient,
comprising a femoral component having a hemispherical portion; an acetabulum
component having a cup-shaped receptacle to receive the hemispherical portion;
a femoral component hole in the femoral component, the femoral component hole
having a port opening toward the acetabulum component, the port of the femoral
component hole being chamfered to a diameter greater than a diameter of the
femoral component hole; an acetabulum component hole in the acetabulum component;
and a ligamentous material extending from the femoral component hole and out
the femoral component hole port and into the acetabulum component to maintain
engagement between the femoral component and the acetabulum component.
13. The prosthesis
of claim 12, wherein the acetabulum component hole has a port opening toward
the femoral component, the port of the acetabulum component hole being
chamfered to a diameter greater than a diameter of the acetabulum component
hole.
14. A hip
prosthesis for implantation into an acetabulum and femur of a patient,
comprising: a femoral component having a hemispherical portion; an acetabulum
component having a cup-shaped receptacle to receive the hemispherical portion;
an acetabulum component hole having a port opening toward the femoral
component, the port of the acetabulum component hole being chamfered to a
diameter greater than a diameter of the acetabulum component hole; a femoral
component hole in the femoral component; and a ligamentous material extending
from the acetabulum component hole and out the acetabulum component hole port
and into the femoral component to maintain engagement between the femoral
component and the acetabulum component.
References Cited
U.S. PATENT DOCUMENTS
2,765,787 10/1956 Pellet 623/23
3.658,056 4/1972 Huggler et al. 623/23
5,389,107 2/1995 Nassar et al. 623/22
5,549,691 8/1996 Harwin 623/22
External links
Dennis DA, Komistek RD. Method and apparatus for hip
prosthesis US5951605 July 1, 1996. 1999.
patents.google
Publications
of invention
CA2262407 (A1)
EP0909149 (A1)
EP0909149 (A4)
US5951605 (A)
WO1998000076 (A1)
1999DennisDA_KomistekRD
Authors & Affiliations
Douglas A. Dennis – Denver, Colo., US.
Richard D. Komistek – Denver, Colo., US.
Keywords
ligamentum capitis femoris, ligamentum teres, ligament
of head of femur, endoprosthesis, prosthesis,
invention, unipolar, subtotal
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