U.S. patent application number 11/089826 was filed with the patent office on 2005-08-04 for device and method for bicompartmental arthroplasty.
Invention is credited to Rolston, Lindsey R..
Application Number | 20050171612 11/089826 |
Document ID | / |
Family ID | 32868136 |
Filed Date | 2005-08-04 |
United States Patent
Application |
20050171612 |
Kind Code |
A1 |
Rolston, Lindsey R. |
August 4, 2005 |
Device and method for bicompartmental arthroplasty
Abstract
Disclosed is a device and method of bicompartmental arthroplasty
of the knee. The device permits arthroplasty of the medial or
lateral and patellofemoral compartments of the knee while leaving
the opposite compartments and the anterior and posterior cruciate
ligaments intact. The device provides a femoral prosthesis
component that includes a trochlear surface and a tibial prosthesis
component which can be secured to the tibia. The femoral component
is essentially "u" shaped having an anterior leg upon which the
trochlear surface is positioned and a posterior leg which engages
the posterior surface of the distal end of the femur. The femoral
component also has a convex articulating surface which engages a
concave articulating surface of the tibial prosthesis component to
approximate the articulation of a healthy knee. The patellar
prosthesis is applied to the posterior surface of the patella and
articulates with the trochlear exterior surface of the femur.
Inventors: |
Rolston, Lindsey R.; (New
Castle, IN) |
Correspondence
Address: |
Homer W. Faucett, III
ICE MILLER
One American Square
Box 82001
Indianapolis
IN
46282-0200
US
|
Family ID: |
32868136 |
Appl. No.: |
11/089826 |
Filed: |
March 25, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11089826 |
Mar 25, 2005 |
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10370002 |
Feb 20, 2003 |
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Current U.S.
Class: |
623/20.19 ;
623/20.3; 623/20.35 |
Current CPC
Class: |
A61F 2002/3895 20130101;
A61F 2220/0033 20130101; A61F 2/38 20130101; A61F 2310/00179
20130101; A61F 2/3877 20130101; A61F 2310/00017 20130101; A61F
2310/00023 20130101; A61F 2310/00029 20130101; A61F 2310/00353
20130101; A61F 2/30767 20130101; A61F 2002/30878 20130101; A61F
2002/4631 20130101; A61F 2310/00131 20130101; A61F 2002/30574
20130101; A61F 2/30771 20130101; A61F 2002/30364 20130101; A61F
2310/00239 20130101 |
Class at
Publication: |
623/020.19 ;
623/020.3; 623/020.35 |
International
Class: |
A61F 002/38 |
Claims
What is claimed is:
1. A method of performing bicompartmental arthroplasty of a
patient's knee comprising the steps of: a. making an incision along
the anterior medial aspect of the knee; b. excising the remnants of
the medial meniscus; c. surgically preparing a medial compartment
of a proximal end of the patient's tibia to receive a medial tibial
prosthesis component in a manner so as to preserve the integrity of
a anterior and posterior cruciate ligaments; said medial tibial
prosthesis component having a first surface configured to be
secured to said surgically prepared medial compartment of the
proximal end of the patient's tibia and a second concave curved
surface; d. rotating a patella approximately 90 degrees; e.
surgically preparing a medial compartment of a distal end of the
patient's femur to receive a medial femoral prosthesis component
having a concave trochlea surface; said medial femoral prosthesis
component also having a first surface configured to be secured to
said surgically prepared medial compartment of the distal end of
the femur and a second convex curved surface configured to
articulate with the second concave curved surface of said medial
tibial prosthesis component to permit pivotal articulation between
said medial femoral prosthesis component and said medial tibial
prosthesis component, said pivotal articulation approximating the
articulation of a healthy knee joint; f. securing a medial femoral
component to the femur; g. securing the medial tibial component to
the tibia; h. positioning the patella over the concave trochlea
surface of the medial femoral prosthesis component; and i. closing
the incision.
2. A method of performing bicompartmental arthroplasty of the knee
as claimed in claim 1, further comprising the additional steps of:
a. surgically preparing a posterior surface of the patient's
patella to receive a patella prosthesis component having a first
surface configured to be secured to said surgically prepared
posterior surface of the patella, and a convex curved second
surface configured to engage the concave trochlea surface of said
medial femoral prosthesis component; and b. securing said patella
prosthesis component to the patella.
3. A method for bicompartmental arthroplasty of the knee as claimed
in claim 1 wherein said medial femoral prosthesis component
comprises a metallic material.
4. A method for bicompartmental arthroplasty of the knee as claimed
in claim 1 wherein said medial femoral prosthesis component
comprises a bio-compatible plastic.
5. A method for bicompartmental arthroplasty of the knee as claimed
in claim 1 wherein said medial tibial prosthesis component
comprises a bio-compatible plastic.
6. A method for bicompartmental arthroplasty of the knee as claimed
in claim 1 wherein said medial tibial prosthesis component
comprises a metallic material.
7. A method for bicompartmental arthroplasty of the knee as claimed
in claim 1 wherein said medial tibial prosthesis component
comprises a bio-compatible plastic and metallic material.
8. A method for bicompartmental arthroplasty of the knee as claimed
in claim 1 wherein said medial femoral prosthesis component and
said medial tibial prosthesis component are dimensioned to permit
the distal end of the femur and the proximal end of the tibia to be
surgically prepared in manner so as to preserve the integrity of
the patient's anterior and posterior cruciate ligaments.
9. A method for bicompartmental arthroplasty of the knee as claimed
in claim 2 further comprising the additional step of: positioning
said convex curved second surface of said patella prosthesis
component to articulate with the concave trochlea surface of said
medial femoral prosthesis component.
10. A method for bicompartmental arthroplasty of the knee as
claimed in claim 1 wherein said femoral prosthesis component is
secured to the femur using a cement.
11. A method for bicompartmental arthroplasty of the knee as
claimed in claim 1 wherein said femoral prosthesis component is
secured to the femur by bone ingrowth into an ingrowth surface
applied to the first surface of the femoral prosthesis
component.
12. A method for bicompartmental arthroplasty of the knee as
claimed in claim 1 wherein said tibial prosthesis component is
secured to the tibia using a cement.
13. A method for bicompartmental arthroplasty of the knee as
claimed in claim 1 wherein said tibial prosthesis component is
secured to the tibia by bone ingrowth into an ingrowth surface
applied to the first surface of the tibial prosthesis
component.
14. A method for bicompartmental arthroplasty of the knee as
claimed in claim 2 wherein said patella prosthesis component is
secured to the patella by cement.
15. A method for bicompartmental arthroplasty of the knee as
claimed in claim 2 wherein said patella prosthesis component is
secured to the patella by bone ingrowth into an ingrowth surface
applied to the first surface of the patella prosthesis
component.
16. A method of performing bicompartmental arthroplasty of a
patient's knee comprising the steps of: a. making an incision along
an anterior medial aspect of the knee; b. excising remnants of a
medial meniscus; c. surgically preparing a medial compartment of a
proximal end of a patient's tibia to receive a medial tibial
prosthesis component in a manner so as to preserve the integrity of
anterior and posterior cruciate ligaments; said medial tibial
prosthesis component having a first surface configured to be
secured to said surgically prepared medial compartment of the
proximal end of the tibia and a second concave curved surface; d.
rotating the patient's patella approximately 90 degrees; e.
surgically preparing the medial compartment of a distal end of the
patient's femur to receive a medial femoral prosthesis component,
said medial femoral prosthesis component having a first leg portion
and a second leg portion and a base portion connected between said
first and second leg portions to form an essentially U-shaped
component, said medial femoral prosthesis component having a first
interior surface configured to be secured to a surgically prepared
medial compartment of a distal end of the patient's femur so that a
base portion of the femoral prosthesis contacts the distal end of
the femur, said first leg portion contacts the anterior surface of
the distal end of the femur, and the second leg portion contacts
the posterior surface of the distal end of the femur, and said
medial femoral prosthesis component also having a second exterior
convex curved surface on said base portion, and an exterior concave
trochlea surface positioned on said first leg portion and
configured to articulate with the patella; said second convex
curved surface on said base portion configured to articulate with
the second concave curved surface of said medial tibial prosthesis
component to permit articulation between said medial femoral
prosthesis component and said medial tibial prosthesis component,
said articulation motion approximating the articulation of a
healthy knee joint; f. securing the medial femoral component to the
femur; g. securing the medial tibial component to the tibia; h.
positioning the patella over the trochlea surface of the medial
femoral prosthesis component; and i. closing the incision.
17. A method of performing bicompartmental arthroplasty of the knee
as claimed in claim 16 comprising the additional steps of: a.
surgically preparing a posterior surface of the patient's patella
to receive a patella prosthesis component having a first surface
configured to be secured to said surgically prepared posterior
surface of the patella, and a convex curved second surface
configured to engage the concave trochlea surface of said medial
femoral prosthesis component; and b. Securing said patella
prosthesis component to the patella.
18. A method for bicompartmental arthroplasty of the knee as
claimed in claim 16 wherein said medial femoral prosthesis
component comprises a metallic material.
19. A method for bicompartmental arthroplasty of the knee as
claimed in claim 16 wherein said medial femoral prosthesis
component comprises a bio-compatible plastic.
20. A method for bicompartmental arthroplasty of the knee as
claimed in claim 16 wherein said medial tibial prosthesis component
comprises a bio-compatible plastic.
21. A method for bicompartmental arthroplasty of the knee as
claimed in claim 16 wherein said medial tibial prosthesis component
comprises a metallic material.
22. A method for bicompartmental arthroplasty of the knee as
claimed in claim 16 wherein said medial tibial prosthesis component
comprises a bio-compatible plastic and metallic material.
23. A method for bicompartmental arthroplasty of the knee as
claimed in claim 16 wherein said medial femoral prosthesis
component and said medial tibial prosthesis component are
dimensioned to permit the distal end of the femur and the proximal
end of the tibia to be surgically prepared in manner so as to
preserve the integrity of the anterior and posterior cruciate
ligaments.
24. A method for bicompartmental arthroplasty of the knee as
claimed in claim 16 wherein said femoral prosthesis component is
secured to the femur using a cement.
25. A method for bicompartmental arthroplasty of the knee as
claimed in claim 16 wherein said femoral prosthesis component is
secured to the femur by bone ingrowth into an ingrowth surface
applied to the first surface of the femoral prosthesis
component.
26. A method for bicompartmental arthroplasty of the knee as
claimed in claim 16 wherein said tibial prosthesis component is
secured to the tibia using a cement.
27. A method for bicompartmental arthroplasty of the knee as
claimed in claim 16 wherein said tibial prosthesis component is
secured to the tibia by bone ingrowth into an ingrowth surface
applied to the first surface of the tibial prosthesis
component.
28. A method for bicompartmental arthroplasty of the knee as
claimed in claim 17 wherein said patella prosthesis component is
secured to the patella by cement.
29. A method for bicompartmental arthroplasty of the knee as
claimed in claim 17 wherein said patella prosthesis component is
secured to the patella by bone ingrowth into an ingrowth surface
applied to the first surface of the patella prosthesis
component.
30. A method for bicompartmental arthroplasty of the knee as
claimed in claim 17 further comprising the additional step of:
positioning said convex curved second surface of said patella
prosthesis component to articulate with the concave trochlea
surface of said medial femoral prosthesis component.
Description
PRIORITY INFORMATION
[0001] This application is a divisional application of application
Ser. No. 10/370,002, titled DEVICE AND METHOD FOR BICOMPARTMENTAL
ARTHROPLASTY, the entirety of which is incorporated herein by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to a device and method for
bicompartmental arthroplasty for resurfacing of either the medial
joint and the patellofemoral joint of the knee or the lateral and
patellofemoral joint of the knee in order to treat the pain
associated with arthritis. The present device and method resurfaces
either the medial or lateral joints depending on which compartment
is diseased, but does not resurface both the lateral (outside) and
medial (inside) compartment of the knee at the same time.
BACKGROUND OF THE INVENTION
[0003] Total knee joint replacement (arthroplasty) is a common and
very successful surgery for people with degenerative arthritis
(osteoarthritis) of the knee. Over 450,000 patients a year in the
United States undergo total knee replacement surgery. Total knee
replacement puts an artificial surface on all parts of the knee
joint that contact each other as the knee bends. The damaged
cartilage is removed, a small amount of bone is removed, the knee
implant is attached to the distal end of the femur and proximal end
of the tibia, and the patella is resurfaced if necessary. The
implant typically is made of metal and plastic and provides an
artificial articulating surface which causes no pain to the
patient. Unfortunately total knee replacement results in sacrifice
of the anterior and posterior cruciate ligaments.
[0004] More recently, unicompartmental knee arthroplasty has been
utilized where there is arthritic damage to only a single
compartment of the knee and no damage to the other compartments.
The inside (medial) component (medial tibial plateau and the medial
femoral condyle) is most commonly involved and replaced using
unicompartmental arthroplasty. However, occasionally, the outside
(lateral) compartment (the lateral tibial plateau and the lateral
femoral condyle) is sometimes involved and must be replaced. Also
the knee cap, i.e., the patellofemoral compartment (the patella and
femoral trochlear notch) may also develop osteoarthritis.
Heretofore, if more than a single compartment of the knee had
arthritic disease, total knee replacement was the only available
treatment. The present invention provides a device and method for
bicompartmental arthroplasty which permits the resurfacing of the
medial and patellofemoral joints of the knee or the
[0005] lateral and patellofemoral joints without the necessity for
resurfacing of the opposite compartment of the knee or the
sacrifice of the anterior or posterior cruciate ligaments.
BRIEF DESCRIPTION OF THE INVENTION
[0006] A device for bicompartmental arthroplasty of a patient's
knee in accordance with the present invention comprises a femoral
prosthesis component configured to resurface the patellofemoral and
one other compartment of the knee i.e., either the medial
compartment or the lateral compartment depending on which
compartment is diseased. The femoral prosthesis component has a
first internal surface configured to be secured to a surgically
prepared distal end of the one other compartment of the patient's
femur so that the anterior and posterior cruciate ligaments remain
intact. The femoral prosthesis component also has a second exterior
convex curved surface positioned and configured to replicate a
femoral condyle for that compartment and a concave trochlea surface
positioned and configured to articulate with the patella. The
device also comprises a tibial prosthesis component configured for
the one other compartment of the knee having a first interior
surface configured to be secured to a surgically prepared proximal
end of the one other compartment of the patient's tibia and a
second concave curved exterior surface configured to receive the
second convex curved surface of the femoral prosthesis component to
permit pivotal articulation between said femoral prosthesis
component and the tibial prosthesis component, approximating the
articulation of a healthy knee joint.
[0007] A method of performing bicompartmental arthroplasty of a
patellofemoral and one other compartment of a patient's knee
comprises the steps of making an incision along the anterior aspect
of the one other compartment of the knee, excising the remnants of
the meniscus of the one other compartment, surgically preparing a
proximal end of the one other compartment of the patient's tibia to
receive a tibial prosthesis component in a manner so as to preserve
the integrity of the anterior and posterior cruciate ligaments. The
tibial prosthesis component has a first surface configured to be
secured to the surgically prepared one other compartment of the
proximal end of the tibia and a second concave curved surface. Next
the patella is rotated approximately 90 degrees. The distal end of
the one other compartment of a the patient's femur is surgically
prepared to receive a femoral prosthesis component. The femoral
prosthesis component has a concave trochlea surface and a first
surface configured to be secured to the surgically prepared one
other compartment of the distal end of the femur. The femoral
component also has a second convex curved surface configured to
replicate the condyle and articulate with the second concave curved
surface of the tibial prosthesis component to permit pivotal
articulation between the femoral prosthesis component and the
tibial prosthesis component in a manner approximating the
articulation of a healthy knee joint. The femoral component is next
secured to the femur and the tibial component is secured to the
tibia. The patella is positioned over the concave trochlea surface
of the femoral prosthesis component and the incision is closed.
[0008] If the patella is also diseased, the method also comprises
the additional steps of surgically preparing a posterior surface of
the patient's patella to receive a patella prosthesis component
having a first surface configured to be secured to the surgically
prepared posterior surface of the patella, and a convex curved
second surface configured to engage the concave trochlea surface of
the femoral prosthesis component, and securing the patella
prosthesis component to the patella.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1A is a perspective view of the articular surface of a
medial femoral prosthesis component in accordance with the present
invention.
[0010] FIG. 1B is a side view of the medial femoral prosthesis
component of FIG. 1.
[0011] FIG. 2 is a front view of the medial femoral prosthesis
component of FIG. 1 and a medial tibial prosthesis component of the
present invention as surgically implanted on a human knee.
[0012] FIG. 3 is a rear view of a device for bicompartmental
arthroplasty of the knee in accordance with the present invention
as surgically implanted on a human knee.
[0013] FIG. 4 is a front view of a device for bicompartmental
arthroplasty in accordance with the present invention as implanted
on a human knee showing the position of the patella on the
device.
[0014] FIG. 5 is a front view of a human knee flexed 90.degree.
showing the medial femoral prosthesis component and the medial
tibial prosthesis component implanted on the knee.
[0015] FIG. 6 is a lateral side view of a knee showing the
positioning of the patella and a patella prosthesis component.
[0016] FIG. 7 is a side view of a patella component that may be
used in conjunction with the present invention.
[0017] FIG. 8 is a side view of one type of medial tibial
prosthesis component for use in connection with the present
invention.
[0018] FIG. 9 is an upper side perspective view of the prosthesis
of FIG. 8.
[0019] FIG. 10 is an upper side perspective view of an alternative
medial tibial prosthesis component that may be used in connection
with the present invention.
[0020] FIG. 11 is a side view of the prosthesis shown in FIG.
10.
[0021] FIG. 12 is a front view of an alternative embodiment of the
present invention for the lateral compartment of the knee as
implanted on a human knee.
[0022] FIG. 13 is a rear view of the embodiment of FIG. 12.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] FIGS. 1A and B illustrate a medial femoral prosthesis
component 10 for use in connection with a combination device for
bicompartmental arthroplasty of the knee. The prosthesis 10 is
essentially unshaped with one leg of the "u" forming the anterior
(front) portion 20 of the prosthesis and the other leg of the "u"
forming the posterior (rear) portion 22 of the prosthesis and a
base portion 21 connecting the anterior and posterior portions 20
and 22. The medial femoral prosthesis component 10 has an interior
first surface 12 which is configured to be secured to a surgically
prepared portion of the distal end of the medial compartment of the
femur 26 as shown in FIG. 2 as will be described in more detail
below. The exterior surface 14 of component 10 has a concave
trochlear groove 16 formed on the anterior surface of the leg 20 of
prosthesis component 10. A convex second surface 18 is formed on
the medial side of the base portion 21 of prosthesis 10 and is
configured to replicate the medial femoral condyle of the knee. A
post 13 is mounted to the interior surface 12 of base portion 21
and extends essentially perpendicularly from that surface. Post 13
is inserted into a hole drilled in the femur during surgical
preparation to aid in securing the component 10 to the femur 26.
More than one post 13 could be mounted to device 10 as
necessary.
[0024] With reference to FIG. 2, the prosthesis component 10 is
shown in position as it would be on the distal end of the femur 26
of the human knee. The anterior leg 20 of the "u" shaped medial
component 10 is positioned over a surgically prepared anterior
surface of the femur 26. With reference to FIG. 3, the posterior
leg portion 22 of medial component 10 extends upwardly along the
posterior surface of a surgically prepared medial compartment of
the distal end of the femur 26. The interior first surface 12 can
be textured to facilitate attachment to the femur using a cement or
it may have a bone ingrowth surface applied so that the bone will
grow into the ingrowth surface thereby securing component 10 to the
femur. Prior to implanting, the distal end of the femur 26 is
surgically prepared to remove the diseased portions of the distal
end of the femur and the remnants of the medial meniscus are
excised or removed. The distal end of the femur is then cut to mate
with the interior surface 12 of component 10 and a hole is drilled
to accommodate post 13. Alternately, a second hole may be drilled
to accommodate a second post or a keel punch may be used to prepare
for a keel in place of the post to secure rotation of the femoral
implant.
[0025] With reference to FIG. 2, a medial tibial prosthesis
component 28 is shown secured to a surgically prepared portion of
the proximal end of the tibia. With reference to FIGS. 8 and 9, the
medial tibial component 28 has a first flat surface 30 and a second
concave surface 32. The concave surface 32 of the medial tibial
component 28 is configured to articulate with the convex second
surface of the medial femoral component 10. Flat surface 30 has a
post 31 extending perpendicularly from that surface and is
configured and adapted to be secured to a surgically prepared
portion of the medial compartment of the tibia 34. Flat surface 30
can be textured to facilitate attachment by cement or it can have a
bone ingrowth surface applied so that the bone will grow into the
ingrowth surface thereby securing the component 28 to the tibia. As
illustrated in FIGS. 2 and 3, a portion of the tibial plateau is
surgically removed so that the medial component 28 can be attached.
The medial tibial component 28 illustrated in FIGS. 8 and 9 is
comprised entirely of a plastic material that is biomedically
compatible with the human body.
[0026] FIGS. 10 and 11 illustrate an alternative embodiment of a
medial tibial prosthesis component for use in connection with the
present invention. The FIG. 10 and 11 component comprises a flat
metallic base 36 to which a plastic insert 38 with a flat base 37
and a concave upper surface 39 is attached either rigidly to or to
allow rotation or movement upon the fixed base plate 37. The
plastic insert 38 can be formed of the same plastic materials as
component 28 illustrated in FIGS. 8 and 9. Metal base portion 36
has a flat first surface 40 and a downwardly extending flange 42
along one edge which is designed and configured to extend into a
corresponding groove cut into the posterior surface of the tibia so
as to aid in securing base section 36 to the tibia. Surface 40 can
either be textured to aid in securing base portion 36 to the tibia
using a cement, or a bone ingrowth surface can be applied to
surface 40 so that base portion 36 can be secured to the tibia by
bone growth into the bone ingrowth surface.
[0027] It can be appreciated from FIGS. 2, 3 and 5 that the lateral
compartment of the knee remains in its natural state due to the
fact that device 10 is affixed only to the medial compartment of
the knee. Consequently, the anterior and posterior cruciate
ligaments 70 and 72 remain intact and are not compromised by the
device 10 or its implantation.
[0028] With reference to FIGS. 4 and 6, patella 50 is shown in its
normal position in the trochlear groove 16 of medial femoral
component 10. The patellar tendon 52 covers the patella and is
attached at one end 54 to the anterior surface of the tibia and the
other end 56 to the quadriceps muscle (not shown). Contraction of
the quadriceps muscles pulls the patella through the trochlear
groove, thereby lifting the tibia.
[0029] If there is arthritic disease of the patella, it may be
necessary to replace the diseased posterior surface of the patella
with a plastic prosthesis component. With reference to FIG. 6,
patella 50 is shown in dotted lines under the patellar tendon 52.
Also shown in dotted lines is a patellar component 58 as it would
be positioned in a surgically prepared posterior surface of the
patella 50. With reference to FIG. 7, a side view of a patella
prosthesis component 58 is shown. Patella component 58 is
configured to have a convex surface 60 configured and dimensioned
to engage and articulate in the trochlea surface 16 of the medial
femoral prosthesis component 10. Patellar insert component 58 also
comprises a surface 62 which includes a post 64 configured and
adapted to be secured to a surgically prepared posterior surface of
the patella.
[0030] As discussed above, the interior surface 12 of femoral
component 10 can either be configured to be secured to the femur by
the use of a cement, or a bone ingrowth surface may be applied to
the interior surface 12 so that the femur bone will grow into and
more permanently secure the femoral component to the femur. Such
bone ingrowth surfaces are well-known in the art and have
previously been used in connection with both unicompartmental and
full knee replacement prosthesis. Similarly, the medial tibial
prosthesis component 28 can either be secured to the tibia by use
of a cement or also by the use of a bone ingrowth surface applied
to the tibial component so that the bone structure of the tibia
will grow into the bone ingrowth surface to more permanently secure
the tibial component to the tibia.
[0031] With reference to FIGS. 3 and 5, it can be seen that the
present invention can be implanted in the knee without disturbing
or damaging the middle third of the knee joint where the anterior
cruciate ligament 70 and the posterior cruciate ligament 72 are
located. Thus, the present invention allows a bicompartmental knee
arthroplasty that preserves the integrity of the anterior and
posterior cruciate ligaments.
[0032] To implant the FIG. 1-4 embodiment in a patient, a 3 to 4
inch longitudinal incision is made on the anterior aspect of the
knee from the medial aspect of the patellar tendon 1 centimeter
below the joint line extending approximately 3 to 4 inches in a
vertical fashion. The incision is opened along the length of the
incision with a medial parapatellar arthrotomy extending in a
minimal fashion into the quadriceps femoris muscle medially.
Alternately, a mid vastus or mini mid vastus or trivector approach
may be employed to arthrotomize the knee joint. The remnants of the
medial meniscus are excised. A portion of the fat pad is excised
with care being taken to preserve the integrity of the anterior and
posterior cruciate ligaments.
[0033] Surface cuts are made on the medial tibial articular surface
using the technology previously employed by the Accuris.RTM.
unicompartmental arthroplasty of Smith and Nephew Orthopedics, Inc.
Alternately, intramedullary or extramedullary alignment guides can
be employed to guide the medial tibial cuts. After the tibial cut
is made, the patella is subluxed or rotated 90.degree.. The
intramedullary canal at the distal end of the femur is exposed
using a 3/8 inch drill bit. An intramedullary rod is inserted into
the distal femur until a distal femoral cutting block is flush
against the distal medial femur. A distal femoral cutting block of
the appropriate angle is attached after the cutting block is pinned
in place, the distal femoral cut is made with an oscillating saw.
The jig is removed and a sizing block is placed against the distal
femur in order to reference the posterior femoral condyles. A
stylus is attached in order to reference the anterior thickness of
the distal femur and the appropriate size of the femoral prosthesis
10 is selected, the appropriate femoral cutting block is attached
to the intramedullary rod in the appropriate rotation. The block is
pinned and the distal anterior cutting block is used to remove the
anterior surface of the distal femur.
[0034] Anterior and posterior chamfer cuts are made from the medial
aspect of the distal femur followed by a posterior femoral cut for
the medial femoral condyle. The anterior chamfer cut is extended
over the medial aspect of the lateral femoral condyle and a
sagittal saw is used to complete the diagonal cut.
[0035] Next, a trial reduction with the femoral component 10 and
tibial component 28 is employed to assure correct surgical
preparation and sizing. The extent of possible arthritic disease of
the patella is next assessed. If there is extensive disease of the
patella, the patella is rotated approximately 90.degree. and an
inset patella reamer is applied to the posterior surface of the
patella and the patella is reamed to permit the inset of a patella
prosthesis component 58. Alternatively, an onset or a mobile
bearing patella prosthesis may be used as is well known in the
art.
[0036] A partial lateral facetectomy is typically performed to
limit the patellar contact with the transition zone of the distal
femur and the femoral component 10. The patellar implant 58 should
be medialized to assist with patella tracking. Release of the
medial collateral ligament and/or postero-medial structures can be
employed as necessary to allow for ligamentous balancing of the
arthroplasty.
[0037] The femoral tibial and patellar implants 10 and 28 are next
either cemented in the usual fashion if the trial reduction is
found to be satisfactory or securely placed over the prepared bone
surface so that bone ingrowth can occur if the components have a
bone ingrowth surface applied. The knee capsule is closed with a
non-absorbable suture followed by skin closure and sterile metal
staples with sterile dressing.
[0038] With reference to FIGS. 12 and 13, an alternative embodiment
of the present invention is shown. While in most cases, the medial
compartment of the knee is more prone to be subject to arthritic
disease than the lateral compartment, in some cases, the lateral
compartment may be diseased while the medial compartment remains
healthy and unaffected. This alternative embodiment is designed for
those situations where the lateral and patellofemoral joints are
affected, but the medial compartment is not.
[0039] A lateral femoral prosthesis component 100 similar to the
medial femoral prosthesis component 10 of FIG. 1 except it is
configured for the lateral compartment rather than the medial
compartment. Lateral femoral prosthesis component 100 is
essentially "u" shaped having a first anterior leg portion 102 and
a second posterior leg portion 104 that are joined by a base
portion (not shown). Anterior leg portion 102 has a trochlear
groove 106 formed on the face thereof to receive and articulate
with the patella. Lateral femoral prosthesis component 100 has an
interior surface within the "u" (not shown) similar to the interior
surface 12 of component 10 that can be secured to a surgically
prepared portion of the lateral compartment of the femur 108 using
either a cement or a bone ingrowth surface as describe
previously.
[0040] A lateral tibial prosthesis component 110 similar to the
medial tibial component 28 of FIGS. 1-4 is shown in FIGS. 12 and 13
as implanted on a surgically prepared lateral compartment of tibia,
112. Component 110 has a flat bottom surface and a concave upper
surface that receives and articulates with a convex outer surface
(not shown) on the base portion of the femoral prosthesis component
100 in the same manner as describe previously with respect to the
FIG. 1 embodiment. Also, tibial component 110 can be fabricated
from both metal base and a plastic insert as shown in FIG. 10 and
11.
[0041] Femoral component 100 and tibial component 110 are also
configured and designed so that they can be implanted without
causing any damage to the middle portion of the knee so that the
anterior and posterior cruciate ligaments remain intact after
implantation.
[0042] It should be appreciated that both femoral prosthesis
components 10 and 100 and tibial prosthesis components 28 and 110
can be fabricated from either a metallic material or from plastic.
Typically, one component is fabricated from one material and the
opposing component is fabricated from the other material so that
there is a metal on plastic articulating joint for wear purposes.
However, both parts could be fabricated from the same material. A
variety of metallic materials can be used including but not limited
to stainless steel, cobalt chrome steel, titanium, Zirconia,
ceramics and tantalum. Also, a variety of plastic materials can be
used including but not limited to polyethylene, polycarbonate-based
polyurethane, and implantable-grade polymethyl methacrylate
(PMMA).
[0043] It should be recognized that the preferred embodiment of the
present invention as described above can be varied or modified
without departing from the spirit and scope of the present
invention as described and claimed in the following claims.
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