U.S. patent application number 15/618536 was filed with the patent office on 2017-09-28 for methods and devices for knee joint replacement with anterior cruciate ligament substitution.
The applicant listed for this patent is The General Hospital Corporation. Invention is credited to Guoan Li, Orhun K. Muratoglu, Harry E. Rubash, Kartik Mangudi Varadarajan, Thomas Zumbrunn.
Application Number | 20170273799 15/618536 |
Document ID | / |
Family ID | 47506914 |
Filed Date | 2017-09-28 |
United States Patent
Application |
20170273799 |
Kind Code |
A1 |
Muratoglu; Orhun K. ; et
al. |
September 28, 2017 |
Methods and Devices for Knee Joint Replacement with Anterior
Cruciate Ligament Substitution
Abstract
Methods and devices are provided for knee joint replacement with
anterior cruciate ligament (ACL) substitution. Generally, the
methods and devices can allow a knee joint to be partially or
totally replaced in conjunction with substitution of the knee
joint's ACL. In one embodiment, a knee replacement prosthesis can
include a medial or lateral femoral implant, a femoral
intercondylar notch structure, a medial or lateral tibial insert,
and an ACL-substitution member. The ACL-substitution member can be
configured to engage with the femoral intercondylar notch structure
during a full range of knee motion and/or during only early knee
flexion.
Inventors: |
Muratoglu; Orhun K.;
(Cambridge, MA) ; Varadarajan; Kartik Mangudi;
(Belmont, MA) ; Li; Guoan; (Milton, MA) ;
Rubash; Harry E.; (Weston, MA) ; Zumbrunn;
Thomas; (Somerville, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
The General Hospital Corporation |
Boston |
MA |
US |
|
|
Family ID: |
47506914 |
Appl. No.: |
15/618536 |
Filed: |
June 9, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14630421 |
Feb 24, 2015 |
9707085 |
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15618536 |
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13547383 |
Jul 12, 2012 |
9005299 |
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14630421 |
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61507434 |
Jul 13, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2/3836 20130101;
A61F 2/08 20130101; A61F 2/3886 20130101; A61F 2002/30688 20130101;
A61F 2/0811 20130101 |
International
Class: |
A61F 2/38 20060101
A61F002/38 |
Claims
1. A medical device, comprising: a tibial implant having an
inferior surface and an opposite, superior surface, the inferior
surface being configured to be fixed to a tibia of a patient; a
femoral implant mateable to the tibial implant and having an
inferior surface and an opposite, superior surface, the superior
surface being configured to be fixed to a femur of the patient, and
the tibial implant being configured to articulate relative to the
femoral implant when the tibial implant is fixed to the tibia and
the femoral implant is fixed to the femur; a femoral intercondylar
notch coupled to the femoral implant; and a post extending from the
superior surface of the tibial implant near an edge thereof such
that the post simulates an anterior cruciate ligament (ACL) when
the tibial implant is fixed to the tibia and the femoral implant is
fixed to the femur, wherein a mediolateral distance measured from a
medial or lateral surface of the post to an adjacent surface of the
femoral intercondylar notch is less than a second mediolateral
distance measured from the medial or lateral surface of the post to
an adjacent surface of the femoral intercondylar notch, the second
measurement being taken at a more posterior location on the post
than the first measurement.
2. The device of claim 1, wherein the mediolateral distance is
measured with the femoral component oriented at or near full
extension relative to the tibia
3. The device of claim 1, wherein the tibial implant has medial and
lateral compartments, the lateral compartment being configured to
be seated on a lateral surface of the tibia such that the lateral
surface is substantially covered by the lateral compartment, and
the medial compartment being configured to be seated on a medial
surface of the tibia such that the medial surface is substantially
covered by the medial compartment.
4. The device of claim 1, wherein the post is integrally formed
with the tibial implant.
5. The device of claim 1, wherein the post is a discrete element
configured to couple to the tibial implant.
6. The device of claim 1, wherein the post is configured to
articulate relative to the femoral intercondylar notch.
7. A medical device, comprising: a tibial implant having an
inferior surface and an opposite, superior surface, the inferior
surface being configured to be fixed to a tibia of a patient; a
femoral implant rateable to the tibial implant and having an
inferior surface and an opposite, superior surface, the superior
surface being configured to be fixed to a femur of the patient, and
the tibial implant being configured to articulate relative to the
femoral implant when the tibial implant is fixed to the tibia and
the femoral implant is fixed to the femur; and a post extending
from the superior surface of the tibial implant near an edge
thereof such that the post simulates an anterior cruciate ligament
(AOL) when the tibial implant is fixed to the tibia and the femoral
implant is fixed to the femur, a medial or lateral surface of the
post being angled in the transverse plane away from the adjacent
femoral intercondylar notch such that distance between the said
medial/lateral surface of the post and the adjacent femoral
intercondylar notch is greater at a posterior location than at an
anterior location on the post,
8. The device of claim 7, wherein the mediolateral distance is
measured with the femoral component oriented at or near full
extension relative to the tibia
9. The device of claim 7, wherein the tibial implant has medial and
lateral compartments, the lateral compartment being configured to
be seated on a lateral surface of the tibia such that the lateral
surface is substantially covered by the lateral compartment, and
the medial compartment being configured to be seated on a medial
surface of the tibia such that the medial surface is substantially
covered by the medial compartment.
10. The device of claim 7, wherein the post is integrally formed
with the tibial implant.
11. The device of claim 7, wherein the post is a discrete element
configured to couple to the tibial implant.
12. The device of claim 7, further comprising a femoral notch
structure coupled to the femoral implant, the femoral notch
structure being configured to prevent the post from impinging on a
lateral surface of the femur through a full range of knee flexion
when the tibial implant is fixed to the tibia and the femoral
implant is fixed to the femur, wherein the post is configured to
articulate relative to the femoral notch structure.
13. A medical device, comprising: a tibial implant having an
inferior surface and an opposite, superior surface, the inferior
surface being configured to be fixed to a tibia of a patient; a
femoral implant mateable to the tibial implant and having an
inferior surface and an opposite, superior surface, the superior
surface being configured to be fixed to a femur of the patient, and
the tibial implant being configured to articulate relative to the
femoral implant when the tibial implant is fixed to the tibia and
the femoral implant is fixed to the femur; and a post extending
from the superior surface of the tibial implant near an edge
thereof such that the post simulates an anterior cruciate ligament
(ACL) when the tibial implant is fixed to the tibia and the femoral
implant is fixed to the femur, a medial and/or lateral surface of
the post designed such that a mediolateral distance between a
medial and/or lateral surface of the post and a longitudinal plane
is greater at a superior location on the post than at an inferior
location on the post, the longitudinal plane being perpendicular to
the transverse plane, and being oriented along a longitudinal
length of the post measured along a line from an anterior edge to a
posterior edge of the post.
14. The device of claim 13, wherein the mediolateral distance is
measured with the femoral component oriented at or near full
extension relative to the tibia.
15. The device of claim 13, wherein such a reduction in
mediolateral distance at a superior location on the post relative
to an inferior location begins at or below the level of a distal
bony resection of the medial/lateral femoral condyle.
16. The device of claim 13, wherein the post is integrally formed
with the tibial implant.
17. The device of claim 13, wherein the post is a discrete element
configured to couple to the tibial implant.
18. The device of claim 13, further comprising a femoral notch
structure coupled to the femoral implant, the femoral notch
structure being configured to prevent the post from impinging on a
lateral surface of the femur through a full range of knee flexion
when the tibial implant is fixed to the tibia and the femoral
implant is fixed to the femur, wherein the post is configured to
articulate relative to the femoral notch structure.
19. A medical device, comprising: a tibial implant having an
inferior surface and an opposite superior surface, the inferior
surface configured to be fixed to a tibia of a patient; a femoral
implant mateable to the tibial implant and having an inferior
surface and an opposite superior surface, the superior surface
configured to be fixed to a femur of the patient, and the tibial
implant configured to articulate relative to the femoral implant
when the tibial implant is fixed to the tibia and the femoral
implant is fixed to the femur; and a post extending from the
superior surface of the tibial implant near an edge thereof such
that the post simulates an anterior cruciate ligament (ACL) when
the tibial implant is fixed to the tibia and the femoral implant is
fixed to the femur; wherein a bone facing surface of the femoral
component is raised near an anterior aspect of a femoral notch
relative to surfaces near the medial and/or lateral aspects of the
femoral notch.
20. A medical device, comprising: a tibial implant having an
inferior surface and an opposite superior surface, the inferior
surface configured to be fixed to a tibia of, a patient; a femoral
implant mateable to the tibial implant and having an inferior
surface and an opposite superior surface, the superior surface
configured to be fixed to a femur of the patient, and the tibial
implant configured to articulate relative to the femoral implant
when the tibial implant is fixed to the tibia and the femoral
implant is fixed to the femur; and a post extending from the
superior surface of the tibial implant near an edge thereof such
that the post simulates an anterior cruciate ligament (ACL) when
the tibial implant is fixed to the tibia and the femoral implant is
fixed to the femur an anterior surface of the tibial insert being
angled anteriorly relative to a plane perpendicular to the tibial
insert base.
Description
CROSS REFERENCES
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/630,421 filed Feb. 24, 2015, which is a
continuation of U.S. patent application Ser. No. 13/547,383 filed
Jul. 12, 2012, now U.S. Pat. No. 9,005,299, which claims priority
to U.S. Provisional Patent Application No. 61/507,434 entitled
"Methods and Devices for Knee Joint Replacement with Anterior
Cruciate Ligament Substitution" filed Jul. 13, 2011, which is
hereby incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to methods and devices for
knee joint replacement with anterior cruciate ligament (ACL)
substitution, and in particular to methods and devices for
substituting a prosthesis for an ACL.
BACKGROUND OF THE INVENTION
[0003] FIG. 1 illustrates a typical knee joint including a femur 1
and a tibia 3, shown with healthy femur cartilage 5 and healthy
tibia cartilage 7. The knee joint includes three primary elements;
a medial tibiofemoral joint, a lateral tibiofemoral joint, and a
central patellofemoral joint. Joint trauma or diseases such as
osteoarthritis and rheumatoid arthritis can cause severe damage to
one or more of these elements. In a case where one or more of the
knee elements are traumatized or diseased, while the other one or
two knee elements are healthy, the traumatized or diseased
element(s) can be replaced in a partial knee replacement surgical
procedure. In a case where all three primary elements are
traumatized or diseased, all three elements can be replaced in a
total knee replacement surgical procedure.
[0004] In both partial and total knee replacement surgical
procedures, the traumatized or diseased ones of the knee's bony
surfaces, e.g., femur, tibia, and patella, can be replaced by
prosthetic components. The knee's soft-tissue structures,
particularly ligaments surrounding the knee joint, can be largely
left intact. The knee's major ligament structures include medial
and lateral collateral structures, and anterior and posterior
cruciate ligaments. These ligamentous structures play a significant
role in controlling the motion and stability of a knee joint. With
regards to the cruciate ligaments, the posterior cruciate ligament
(PCL) is generally present and well-functioning in patients
undergoing partial or total knee replacement surgery. However, in
at least some patients, the anterior cruciate ligament (ACL) can be
absent or non-functional at surgery due to prior trauma or gradual
degradation.
[0005] Traditional partial knee replacement prostheses have no
mechanism for substitution of ACL function. Consequently, patients
with an absent or non-functional ACL may end up receiving total
joint replacement, which is a generally more invasive procedure
than partial knee replacement and which replaces the healthy
element(s) of the patient's knee. Alternatively, instead of total
knee replacement, patients with an absent or non-functional ACL may
undergo additional surgery prior to a partial knee replacement
surgical procedure to reconstruct the ACL, such as with a soft
tissue graft.
[0006] In traditional total knee replacement surgical procedures,
patients receive a type of prosthesis, e.g., a cruciate retaining
(CR) type implant, that allows the present and well-functioning PCL
to be retained. However, even for patients who have a functional
ACL, the ACL is traditionally resected during surgery prior to
implantation of a CR type implant because of difficulty in
achieving optimal soft-tissue balancing and component placement
with both the ACL and PCL present. However, traditional CR
prostheses have no mechanism for substitution of the ACL function.
Consequently, following CR prosthesis implantation, the knee shows
abnormal motion patterns characterized by features such as reduced
tibial internal rotation and paradoxical anterior femoral
translation.
[0007] Accordingly, there remains a need for improved knee
prostheses and methods for treating disease and trauma affecting
the knee.
SUMMARY OF THE INVENTION
[0008] The present invention generally provides methods and devices
for knee joint replacement with anterior cruciate ligament (ACL)
substitution. In one aspect, a medical device is provided that
includes a tibial implant, a femoral implant, and a post. The
tibial implant has an inferior surface and an opposite, superior
surface. The inferior surface is configured to be fixed to a tibia
of a patient. The femoral implant is mateable to the tibial implant
and has an inferior surface and an opposite, superior surface. The
superior surface of the femoral implant is configured to be fixed
to a femur of the patient, and the tibial implant is configured to
articulate relative to the femoral implant when the tibial implant
is fixed to the tibia and the femoral implant is fixed to the
femur. The post extends from the superior surface of the tibial
implant near an edge thereof. The post is configured to be
substantially centered on the tibia when the tibial implant is
fixed thereto such that the post simulates an ACL when the tibial
implant is fixed to the tibia and the femoral implant is fixed to
the femur.
[0009] The tibial implant can have a variety of configurations. The
tibial implant can have a medial compartment configured to be
seated on a medial surface of the tibia with a first portion of the
tibial implant being seated on or over the tibia's medial surface
and a second, substantially smaller portion of the tibial implant
being seated on or over the tibia's lateral surface. The tibial
implant can have a lateral compartment configured to be seated on a
lateral surface of the tibia with a first portion of the tibial
implant being seated on or over the tibia's lateral surface and a
second, substantially smaller portion of the tibial implant being
seated on or over the tibia's medial surface. The tibial implant
can have medial and lateral compartments. The lateral compartment
can be configured to be seated on a lateral surface of the tibia
such that the lateral surface is substantially covered by the
lateral compartment. The medial compartment can be configured to be
seated on a medial surface of the tibia such that the medial
surface is substantially covered by the medial compartment.
[0010] The post can have a variety of configurations. The post can
be asymmetric in sagittal, coronal, and transverse planes. The post
can be integrally formed with the tibial implant, or the post can
be a discrete element configured to couple to the tibial
implant.
[0011] In some embodiments, the device can include a femoral notch
structure coupled to the femoral implant. The femoral notch
structure can be configured to prevent the post from impinging on a
lateral surface of the femur through a full range of knee flexion
when the tibial implant is fixed to the tibia and the femoral
implant is fixed to the femur. The post can be configured to
articulate relative to the femoral notch structure.
[0012] In another aspect, a medical method is provided that
includes implanting a partial knee prosthesis in a patient to
replace one of a medial tibiofemoral joint of a knee and a lateral
tibiofemoral joint of the knee such that an inferior surface of a
tibial implant of the knee prosthesis faces a tibia of the knee, a
superior surface of the tibial implant faces an inferior surface of
a femoral implant of the knee prosthesis, a superior surface of the
femoral implant faces a femur of the knee, and a post extending
from the superior surface of the tibial implant functions as a
substitute for an ACL of the knee. The tibial implant and the post
are configured to articulate relative to the femoral implant, and
the post does not impinge on a lateral surface of the femur when
the post articulates relative to the femoral implant through a full
range of knee flexion.
[0013] In another embodiment, a medical method is provided, that
includes implanting a total knee prosthesis in a patient to replace
both of a medial tibiofemoral joint of a knee and a lateral
tibiofemoral joint of the knee such that an inferior surface of a
tibial implant of the knee prosthesis faces a tibia of the knee, a
superior surface of the tibial implant faces an inferior surface of
a femoral implant of the knee prosthesis, a superior surface of the
femoral implant faces a femur of the knee, and a post extending
from the superior surface of the tibial implant functions as a
substitute for an ACL of the knee. The tibial implant and the post
are configured to articulate relative to the femoral implant, and
the post does not impinge on a lateral surface of the femur when
the post articulates relative to the femoral implant through a full
range of knee flexion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention will be more fully understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0015] FIG. 1 (PRIOR ART) is a perspective view of a typical normal
human knee;
[0016] FIG. 1A is view of one embodiment of a knee prosthesis
having an ACL-substitution member including a plurality of discrete
pieces;
[0017] FIG. 1B is a top view of one embodiment of a knee
prosthesis;
[0018] FIG. 1C is a sagittal cross-sectional view of the knee
prosthesis of FIG. 1B;
[0019] FIG. 1D is a coronal cross-sectional view of the knee
prosthesis of FIG. 1B;
[0020] FIG. 1E is a side view of one embodiment of a knee
prosthesis including an ACL-substitution member and a femoral notch
structure configured to engage through a full range of knee
motion;
[0021] FIG. 1F is top, partial view of one embodiment of a tibial
insert;
[0022] FIG. 1G is coronal section view B-B of the tibial insert of
FIG. 1F and a femoral implant;
[0023] FIG. 2 is a posterior perspective view of one embodiment of
a medial knee prosthesis attached to a tibia arid a femur;
[0024] FIG. 3 is a posterior perspective view of one embodiment of
a lateral knee prosthesis attached to a tibia and a femur;
[0025] FIG. 4 is a top view of a tibial insert of the medial knee
prosthesis of FIG. 2 seated on the tibia;
[0026] FIG. 5 is a side perspective view of the tibial insert of
FIG. 4;
[0027] FIG. 6 is a top view of a tibial insert of the lateral knee
prosthesis of FIG. 3;
[0028] FIG. 7 is a side view of the tibial insert of FIG. 6;
[0029] FIG. 8 is a perspective view of the tibial insert of FIG.
6;
[0030] FIG. 8A is a side view of one embodiment of a knee
prosthesis including a tibial post located substantially anterior
to tibial center;
[0031] FIG. 8B is top view of the femoral component of the
prosthesis of FIG, 8A;
[0032] FIG. 8C is a top view of the prosthesis of FIG. 8A;
[0033] FIG. 9 is a top view of the tibial insert of the lateral
knee prosthesis of FIG. 3 seated on the tibia;
[0034] FIG. 10 is another top view of the tibial insert of FIG.
9;
[0035] FIG. 11 is a perspective view of one embodiment of a medial
knee prosthesis attached to a tibia, the medial knee prosthesis
including a post gradually blending into a tibial insert of the
prosthesis;
[0036] FIG. 12 is a schematic view of one embodiment of a lateral
knee prosthesis including a tibial post and a tibial insert, the
tibial post having a lateral edge extending back to a posterior
edge of the tibial insert;
[0037] FIG. 13 is a top view of the medial knee prosthesis of FIG.
2 attached to the tibia;
[0038] FIG. 13A is a top view of an embodiment of a lateral knee
prosthesis attached to a tibia;
[0039] FIG. 14 is a side perspective view of the medial knee
prosthesis of FIG. 13;
[0040] FIG. 14A is a side perspective view of the lateral knee
prosthesis of FIG. 13A;
[0041] FIG. 15 is a top view of one embodiment of a medial knee
prosthesis attached to a tibia, the prosthesis including a discrete
femoral notch structure and a discrete femoral implant;
[0042] FIG. 16 is a side perspective view of the medial knee
prosthesis of FIG. 15;
[0043] FIG. 17 is a perspective view of one embodiment of a lateral
knee prosthesis in an extended or closed position;
[0044] FIG. 18 is a perspective view of the prosthesis of FIG. 17
in a flexed or open position;
[0045] FIG. 19 is a top view of one embodiment of a lateral knee
prosthesis attached to a tibia, the prosthesis including a post
having a rounded top;
[0046] FIG. 20A is aside schematic view of the prosthesis of FIG.
19;
[0047] FIG. 20B is a side schematic view of one embodiment of a
lateral knee prosthesis attached to a tibia, the prosthesis
including a post having an angled or chamfered top;
[0048] FIG. 20C is a side view of an embodiment of a bone shaping
tool;
[0049] FIG. 20D is a top view of another embodiment of a bone
shaping tool adjacent to an embodiment of a femoral component;
[0050] FIG. 20E is a top view of an embodiment of a femoral trial
component that includes one or more guiding slots;
[0051] FIG. 20F is a side view of an embodiment of a trial tibial
insert that has a larger size than an embodiment of a tibial
insert;
[0052] FIG. 20G is a side view of the trial tibial insert of FIG.
20F positioned adjacent a femoral bone and an embodiment of a
femoral component;
[0053] FIG. 21 are top schematic views of one embodiment of a
lateral knee prosthesis including a tibial post and a femoral
intercondylar structure, the post, an anterior surface, and a
lateral surface of the femoral intercondylar structure having
concentric circular profiles;
[0054] FIG. 21A is top, partial view of one embodiment of a
prosthesis including a tibial post including angled cuts;
[0055] FIG. 21B is a perspective, partial view of the prosthesis of
FIG, 21A;
[0056] FIG. 21C is a sagittal section view A-A of the tibial insert
of FIG. 21A;
[0057] FIG. 21D is a coronal section view B-B of the tibial insert
of FIG. 21A;
[0058] FIG. 22 is a top view of one embodiment of a medial knee
prosthesis attached to a tibia, the prosthesis having a convex
tibial post and a convex femoral intercondylar notch;
[0059] FIG. 23 is a schematic, sagittal plane cross-sectional view
of the prosthesis of FIG. 22;
[0060] FIG. 24 is a schematic, sagittal plane cross-sectional view
of one embodiment of a medial knee prosthesis, the prosthesis
having a concave tibial post and a convex femoral intercondylar
notch;
[0061] FIG. 25 is a schematic, sagittal plane cross-sectional view
of one embodiment of a medial knee prosthesis, the prosthesis
having a convex tibial post and a concave femoral intercondylar
notch;
[0062] FIG. 26 is a schematic, sagittal plane cross-sectional view
of one embodiment of a medial knee prosthesis, the prosthesis
having a flat tibial post and a convex femoral intercondylar
notch;
[0063] FIG. 27 is a schematic, sagittal plane cross-sectional view
of one embodiment of a medial knee prosthesis, the prosthesis
having a convex tibial post and a flat femoral intercondylar
notch;
[0064] FIG. 28 is a top view of one embodiment of a lateral knee
prosthesis attached to a tibia, the prosthesis having a concave
tibial post and a convex femoral intercondylar notch;
[0065] FIG. 29 is a schematic, coronal plane cross-sectional view
of the prosthesis of FIG. 28;
[0066] FIG. 30 is a schematic, coronal plane cross-sectional view
of one embodiment of a lateral knee prosthesis attached to a tibia,
the prosthesis having a flat tibial post and a flat femoral
intercondylar notch;
[0067] FIG. 31 is a schematic, coronal plane cross-sectional view
of one embodiment of a lateral knee prosthesis attached to a tibia,
the prosthesis having a convex tibial post and a convex femoral
intercondylar notch;
[0068] FIG. 32 is a schematic, coronal plane cross-sectional view
of one embodiment of a lateral knee prosthesis attached to a tibia,
the prosthesis having a flat tibial post and a convex femoral
intercondylar notch;
[0069] FIG. 33 is a schematic, coronal plane cross-sectional view
of one embodiment of a lateral knee prosthesis attached to a tibia,
the prosthesis having a convex tibial post and a flat femoral
intercondylar notch;
[0070] FIG. 34 is a top perspective view of one embodiment of a
total knee replacement prosthesis;
[0071] FIG. 35 is a perspective view of one embodiment of a total
knee replacement prosthesis attached to a femur, the prosthesis
being in an extended or closed position and including a femoral
notch structure;
[0072] FIG. 36 is a perspective view of the prosthesis of FIG. 35
not attached to bone and in a flexed or open position;
[0073] FIG. 37 is a perspective view of the prosthesis of FIG. 34
attached to a femur and showing a representation of a PCL
ligament;
[0074] FIG. 38 is a perspective view of the prosthesis of FIG. 37
not attached to bone and with the representation of the PCL
ligament in positions corresponding to different knee flexion
angles;
[0075] FIG. 39 is a top view of a tibial implant of the prosthesis
of FIG. 34;
[0076] FIG. 40 is a side view of the tibial implant of FIG. 39;
[0077] FIG. 41 is a perspective view of the tibial implant of FIG.
39;
[0078] FIG. 42 is a top view of the tibial implant of FIG. 39;
[0079] FIG. 43 is another top view of the tibial implant of FIG.
39;
[0080] FIG. 44 is a perspective view of one embodiment of a total
knee replacement prosthesis including a post gradually blending
into a tibial insert of the prosthesis;
[0081] FIG. 45 is a schematic view of one embodiment of a total
knee replacement prosthesis including a tibial post and a tibial
insert, the tibial post having a lateral edge extending back to a
posterior edge of the tibial insert;
[0082] FIG. 46 is a perspective view of one embodiment of a total
knee replacement prosthesis attached to a femur and having a post
with a height configured to avoid impingement with the lateral
femoral condyle;
[0083] FIG. 47 is a top view of one embodiment of a total knee
replacement prosthesis including a post having a rounded top;
[0084] FIG. 48 is a side schematic view of the prosthesis of FIG.
47;
[0085] FIG. 49 is a perspective view of one embodiment of a total
knee replacement prosthesis in an extended or closed position;
[0086] FIG. 50 is a perspective view of the prosthesis of FIG. 49
in a flexed or open position;
[0087] FIG. 51 is a top view of one embodiment of a total knee
replacement prosthesis having a convex tibial post and a convex
femoral intercondylar notch;
[0088] FIG. 52 is a top view of one embodiment of a total knee
replacement prosthesis having a concave tibial post and a convex
femoral intercondylar notch;
[0089] FIG. 53 is a schematic, coronal plane cross-sectional view
of the prosthesis of FIG. 52 attached to a tibia;
[0090] FIG. 54 is a schematic, coronal plane cross-sectional view
of one embodiment of a total knee replacement prosthesis attached
to a tibia, the prosthesis having a flat tibial post and a flat
femoral intercondylar notch;
[0091] FIG. 55 is a schematic, coronal plane cross-sectional view
of one embodiment of a total knee replacement prosthesis attached
to a tibia, the prosthesis having, a convex tibial post and a
convex femoral intercondylar notch;
[0092] FIG. 56 is a schematic, coronal plane cross-sectional view
of one embodiment of a total knee replacement prosthesis attached
to a tibia, the prosthesis having a flat tibial post and a convex
femoral intercondylar notch;
[0093] FIG. 57 is a schematic, coronal plane cross-sectional view
of one embodiment of a total knee replacement prosthesis attached
to a tibia, the prosthesis having a convex tibial post and a flat
femoral intercondylar notch;
[0094] FIG. 58 is a graph showing motion of a medial flexion facet
center (FFC) of a total knee replacement prosthesis as a function
of knee flexion during a simulated lunge activity for a
ACL-substituted CR implant of the prosthesis and for a conventional
CR implant;
[0095] FIG. 59 is a graph showing motion of a lateral FFC of the
prosthesis of FIG. 58 as a function of knee flexion during a
simulated lunge activity for the ACL-substituted CR implant and for
a conventional CR implant;
[0096] FIG. 60 is a graph showing motion of the medial FFC of the
prosthesis of FIG. 58 as a function of knee flexion during a
simulated deep knee bending activity for the ACL-substituted CR
implant and for a conventional CR implant;
[0097] FIG. 61 is a graph showing motion of the lateral FFC of the
prosthesis of FIG. 58 as a function of knee flexion during a
simulated deep knee bending activity for the ACL-substituted CR
implant and for a conventional CR implant;
[0098] FIG. 62 is a graph showing motion of the medial FFC of the
prosthesis of FIG. 58 as a function of knee flexion during a
simulated chair rise/sit activity for the ACL-substituted CR
implant and for a conventional CR implant;
[0099] FIG. 63 is a graph showing motion of the lateral FFC of the
prosthesis of FIG. 58 as a function of knee flexion during a
simulated chair rise/sit activity for the ACL-substituted CR
implant and for a conventional CR implant;
[0100] FIG. 64 is a graph showing motion of the medial FFC of the
prosthesis of FIG. 58 as a function of knee flexion during a
simulated stair ascent activity for the ACL-substituted CR implant
and for a conventional CR implant;
[0101] FIG. 65 is a graph showing motion of the lateral FFC of the
prosthesis of FIG. 58 as a function of knee flexion during a
simulated stair ascent activity for the ACL-substituted CR implant
and for a conventional CR implant;
[0102] FIG. 66 is a graph showing motion of the medial FFC of the
prosthesis of FIG. 58 as a function of knee flexion during
simulated walking for the ACL-substituted CR implant and for a
conventional CR implant;
[0103] FIG. 67 is a graph showing motion of the lateral FFC of the
prosthesis of FIG. 58 as a function of knee flexion during
simulated walking for the ACL-substituted CR implant and for a
conventional CR implant;
[0104] FIG. 68 is a medial/lateral cross-sectional view of one
embodiment of a tibial insert of a knee prosthesis having a reduced
articular surface;
[0105] FIG. 69A is a medial/lateral cross-sectional view of another
embodiment of a tibial insert of a knee prosthesis having a reduced
articular surface;
[0106] FIG. 69B is a side view of the tibial insert of FIG. 69A
adjacent a femur;
[0107] FIG. 70 is a medial/lateral cross-sectional view of yet
another embodiment of a tibial insert of a knee prosthesis having a
reduced articular surface;
[0108] FIG. 71 is a medial/lateral cross-sectional view of an
embodiment of a tibial insert having a concave medial profile and a
convex lateral profile;
[0109] FIG. 72 is a medial/lateral cross-sectional view of an
embodiment of a tibial insert having an angled anterior edge;
[0110] FIG. 73 is a medial/lateral cross-sectional view of an
embodiment of a tibial insert of a knee prosthesis having a reduced
distal femoral condyle radius, the tibial insert shown adjacent a
femur;
[0111] FIG. 74A is a side, partially transparent view of an ACL and
PCL substituting prosthesis including a femoral component and a
tibial insert including a tibial post;
[0112] FIG. 74B is another view of the prosthesis of FIG. 74A;
[0113] FIG. 75 is a partial side cross-sectional view of an
embodiment of a femoral component mated to an anterior and
posterior tibial post, the femoral component having an increased
thickness and radius;
[0114] FIG. 76 is a partial side cross-sectional view of an
embodiment of a femoral component mated to an anterior and
posterior tibial post, the femoral component having an increased
radius;
[0115] FIG. 77 is a top view of one embodiment of a tibial post
having a convex profile, the tibial post engaged with a femoral
notch having a rounded profile;
[0116] FIG. 78 is top view and a perspective view of one embodiment
of a tibial post having a convex profile engaged with a femoral
notch having a concave profile;
[0117] FIG. 79 is a side view of one embodiment of a tibial post
engaging a femoral cam;
[0118] FIG. 80A is a sagittal view of an embodiment of a tibial
post that is angled posteriorly;
[0119] FIG. 80B is a sagittal view of an embodiment of a tibial
post that has an anteriorly angled anterior surface and a
posteriorly angled posterior surface;
[0120] FIG. 81A is a top view of one embodiment of a tibial implant
including a movable lateral tibial insert;
[0121] FIG. 81B is a side cross-sectional view of a portion of the
tibial implant of FIG. 81A;
[0122] FIG. 81C is a side view of an embodiment of a tibial
baseplate having a substantially flat top surface profile;
[0123] FIG. 81D is a coronal cross-sectional view of a portion of
the tibial implant of FIG. 81A;
[0124] FIG. 81E is a coronal cross-sectional view of an embodiment
of a tibial implant having a baseplate with a substantially flat
profile;
[0125] FIG. 81F is a coronal cross-sectional view of an embodiment
of a tibial implant having a baseplate with a substantially convex
profile;
[0126] FIG. 82A is a top view of an embodiment of a tibial implant
including a movable medial tibial insert and a movable lateral
insert;
[0127] FIG. 82B is a side view of an embodiment of a tibial
baseplate having a substantially flat top surface profile and
opposed side rails for a medial tibial insert and opposed side
rails for a lateral tibial insert;
[0128] FIG. 82C is a side view of an embodiment of a tibial
baseplate having a relatively small radius convex structure on a
top surface thereof configured to movably mate a tibial insert
thereto; and
[0129] FIG. 82D is a side view of an embodiment of a tibial
baseplate having a relatively large radius convex top surface
thereof configured to movably mate a tibial insert thereto.
DETAILED DESCRIPTION OF THE INVENTION
[0130] Certain exemplary embodiments will now be described to
provide an overall understanding of the principles of the
structure, function, manufacture, and use of the devices and
methods disclosed herein. One or more examples of these embodiments
are illustrated in the accompanying drawings. Those skilled in the
art will understand that the devices and methods specifically
described herein and illustrated in the accompanying drawings are
non-limiting exemplary embodiments and that the scope of the
present invention is defined solely by the claims. The features
illustrated or described in connection with one exemplary
embodiment may be combined with the features of other embodiments.
Such modifications and variations are intended to be included
within the scope of the present invention.
[0131] Various exemplary methods and devices are provided for knee
joint replacement with anterior cruciate ligament (ACL)
substitution. In general, the methods and devices can allow a knee
joint to be partially or totally replaced in conjunction with
substitution of the knee joint's ACL. In other words, when an ACL
is absent, non-functional, or otherwise needs repair during a
partial or total knee replacement surgical procedure, a partial or
total knee replacement prosthesis can be implanted in the same
surgical procedure as an ACL substitute. Providing, a substitute
for an ACL with a knee replacement prosthesis can help reduce a
number of surgical procedures needed to repair the knee and/or can
help the knee's functionality approach 100% after surgery.
[0132] The prostheses described herein can be formed of one or more
materials, such as polyolefins, polyethylene, ultra-high molecular
weight polyethylene, medium-density polyethylene, high-density
polyethylene, medium-density polyethylene, highly crosslinked
ultra-high molecular weight polyethylene (UHMWPE), etc. Exemplary
embodiments of UHMWPE prosthesis materials and manufacturing
processes are described in U.S. application Ser. No. 08/600,744
(now U.S. Pat. No. 5,879,400) filed Feb. 13, 1996, entitled
"Melt-Irradiated Ultra High Molecular Weight Polyethylene
Prosthetic Devices;" U.S. application Ser. No. 12/333,572 filed
Dec. 12, 2008, entitled "Radiation And Melt Treated Ultra High
Molecular Weight Polyethylene Prosthetic Devices;" U.S. application
Ser. No. 11/564,594 (now U.S. Pat. No. 7,906,064) filed Nov. 29,
2006, entitled "Methods For Making Oxidation Resistant Polymeric
Material;" U.S. application Ser. No. 12/522,728 filed Apr. 5, 2010,
entitled "Methods For Making Oxidation-Resistant Cross-Linked
Polymeric Materials;" U.S. application Ser. No. 11/030,115 (now
U.S. Pat. No. 7,166,650) filed Jan. 7, 2005, entitled "High Modulus
Crosslinked Polyethylene With Reduced Residual Free Radical
Concentration Prepared Below The Melt;" U.S. application Ser. No.
12/041,249 filed Mar. 3, 2008, entitled "Cross-Linking Of
Antioxidant-Containing Polymers;" which are hereby incorporated by
reference in their entireties.
[0133] Generally, a knee replacement prosthesis, also referred to
herein as a "knee replacement prosthesis," a "prosthesis." and an
"implant," can include a medial or lateral femoral component, also
referred to herein as a "femoral implant," a femoral intercondylar
notch structure, a medial or lateral tibial insert, also referred
to herein as a "tibial implant," and an ACL-substitution member,
also referred to herein as an "ACL-substitution member," "ACL
substituting post," a "tibial post," and a "post." The femoral
intercondylar notch structure can be formed integrally with the
femoral component, or the femoral intercondylar notch structure can
be a discrete element from the femoral component. The
ACL-substitution member can be configured to engage with the
femoral intercondylar notch structure, also referred to herein as a
"femoral intercondylar notch structure" and a "femoral notch
structure." The ACL-substitution member can extend from a surface
of the tibial insert, such as by being an integral part thereof, by
being integrally formed with another portion of the prosthesis, or
by being a discrete element configured to couple to the tibial
insert. In an exemplary embodiment, the ACL-substitution member can
be integrally formed with a tibial baseplate of the prosthesis. In
other exemplary embodiments, the ACL-substitution member can be
integrally formed with the tibial insert and extend from a tibial
articular surface thereof. The ACL-substitution member can be a
unitary or singular element, or it can include a plurality of
discrete pieces. FIG. 1A illustrates an exemplary embodiment of a
prosthesis 8 having an ACL-substitution member 10 including
multiple pieces, e.g., an anterior piece 10a and a lateral piece
10b, configured to engage with corresponding regions of the femoral
notch. For reference, a top side of FIG. 1A is an anterior side of
the prosthesis 8, and, a right side of FIG. 1A is a lateral side of
the prosthesis 8. Thus, an anterior part 12 of the anterior piece
10a is on a left side of FIG. 1A, and a posterior lateral part 14
of the lateral piece 10b is on a bottom side of FIG. 1A. Exemplary
embodiments of articular surface geometry are described in Intl.
App. No. PCT/US2010/059387 filed Dec. 8, 2010, entitled "Implant
For Restoring Normal Range Of Flexion And Kinematics Of The Knee,"
which is hereby incorporated by reference in its entirety.
[0134] Embodiments of prostheses described herein can generally be
configured to substitute the function of an ACL via engagement of
the femoral intercondylar notch with the prosthesis, e.g., with the
ACL-substitution member of the prosthesis, during a full range of
knee motion, e.g., in a range of about -20.degree. to 160.degree.
knee flexion, and/or during only early knee flexion, e.g., in a
range of about -20.degree. to 40.degree.. In an exemplary
embodiment, the ACL-substitution member configured to engage the
femoral intercondylar notch can have a low profile, e.g., be a
short post. In another embodiment of a prosthesis 16, shown in
FIGS. 1B, 1C, and 1D, an ACL-substitution member configured to
engage the femoral intercondylar notch can include a two-step
eminence between the medial and lateral tibial plateau that blends
smoothly with the medial and lateral articular surfaces in the
coronal and sagittal planes. Radii R1, R2, R3, R4 of the prosthesis
16 can be in a range of about 2 to 100 mm, e.g., about 2 to 30 mm,
about 5 to 25 mm, about 12 to 20 mm, about 25 to 50 mm, about 55 to
95 mm, etc. The radii R1 and R3 are at a tibial eminence of the
prosthesis 16, e.g., at an ACL-substitution member 18 of the
prosthesis 16. In an exemplary embodiment, the radii R1 and R3 can
each be about 10 mm, and the radii R2 and R4 can each be about 5
mm.
[0135] In another embodiment, a prosthesis can be configured to
restrict mediolateral motion of the prosthesis's femoral component,
which can prevent impinging, a PCL between the femoral component
and the prosthesis's tibial post and can prevent impinging the
tibial post against femoral bone. An exemplary embodiment of such a
prosthesis is illustrated in FIGS. 1F and 1G in which a central
eminence portion 216 of a tibial articular surface adjacent a post
222 of a tibial insert 218 substantially conforms to a surface of a
femoral implant 220 mateable to the tibial insert 218. This
substantial, conformity can restrict mediolateral motion of the
femoral implant 220 and thereby prevent impingement of a PCL and/or
femoral bone against the post 222.
[0136] Embodiments of prostheses described herein can be configured
to be fixed to a patient's tibia, which can facilitate healing
and/or functionality of the prosthesis. In one embodiment, the
prosthesis can be configured to be directly fixed to a tibia using
bone cement. As will be appreciated by a person skilled in the art,
any bone cement can be used to so affix the prosthesis. In another
embodiment, the prosthesis can be nonremovably coupled to a base,
e.g., a biocompatible metallic base. The metal base can be
configured to be fixed to a tibia by using bone cement and/or by
bone ingrowth or ongrowth at the bone/base interface. In yet
another embodiment, the prosthesis can be molded into a base, e.g.,
a biocompatible metallic base, by forming a monoblock implant. In
still another embodiment, the prosthesis can be removably coupled
to a base, e.g., a biocompadble metallic base using a locking
mechanism. The locking mechanism can be configured to be actuated
to affix the prosthesis to the base either during manufacture or
intraoperatively during surgery.
[0137] In use, with the prosthesis implanted in a patient, during
knee flexion from an extended position, the ACL-substitution member
can be configured to engage with the femoral notch structure, which
can prevent the patient's femur from displacing posteriorly, and
can gradually guide the femur's external rotation. In an exemplary
embodiment, during knee flexion from an extended position, anterior
and lateral edges of the ACL-substitution member can be configured
to engage with anterior and lateral, edges of the femoral notch
structure. With the prosthesis implanted in the patient, during
terminal extension from a flexed position, the ACL-substitution
member can be configured to engage with the femoral notch
structure, which can pull the patient's femur forward, and can
gradually guide the femur's internal rotation. Generally, as
illustrated in an embodiment shown in FIG. 1E, an ACL-substitution
member 20 and a femoral notch structure 22 can be configured to
engage through the full range of knee motion. The femoral notch
structure 22 is shown in cross-section in FIG. 1E at different
flexion angles. In an exemplary embodiment, this engagement can
occur during only early knee flexion, e.g., in a range of about
-20.degree. to 40.degree.. In this way, the ACL-substitution member
and the femoral notch engagement can be configured to substitute
for an absent, non-functional, or otherwise damaged ACL ligament.
The knee replacement prosthesis can also be configured to
accommodate a patient's PCL. Because a patient's PCL can be
generally present and well-functioning in patients undergoing
partial or total knee replacement surgery, the prosthesis can be
implanted in the patient while allowing the patient's PCL to remain
and be functional in the patient's body.
[0138] Knee replacement prostheses described herein can be
configured to be used in partial knee replacement surgical
procedures and in total knee replacement surgical procedures.
Exemplary embodiments of prostheses for both types of procedures
are discussed in turn below.
[0139] FIG. 2 illustrates an exemplary embodiment of a knee
replacement prosthesis configured to provide substitution of an ACL
in partial knee replacement surgery. The prosthesis of FIG. 2 is a
medial femoral prosthesis configured to resurface a medial tibial
compartment. In FIG. 2 showing the prosthesis implanted in a
patient, the patient's PCL ligament 24 is represented as a cylinder
joining the tibial insertion of the ligament 24 to its insertion on
the medial femoral condyle within the intercondylar region. As in
the illustrated embodiment, the prosthesis can include a femoral
implant 26, a tibial implant 28, an ACL-substituting post 30, and a
femoral notch structure 32. The prosthesis shown in FIG. 2 is a
medial prosthesis, but a lateral prosthesis can be configured
similarly to the prosthesis of FIG. 2. Further, any medial
prosthesis described herein can be similarly configured as a
lateral prosthesis, and vice versa. FIG. 3 illustrates an exemplary
embodiment of a lateral knee replacement prosthesis including a
femoral implant 34, a tibial implant 36, an ACL-substituting post
38, and a femoral notch structure 40 configured to provide
substitution of an ACL in partial knee replacement surgery and to
resurface a lateral tibial compartment. FIG. 3 also represents the
patient's PCL ligament 42 as a cylinder.
[0140] The tibial implant 36 can have a variety of configurations.
Although in the illustrated embodiment the post 38 is integrally
formed with the tibial implant 36, in some embodiments, the post 38
and the tibial implant 36 can be discrete elements. If the post and
the tibial implant are discrete elements, in any of the embodiments
described herein, the post can be configured to removably and
replaceably couple to the tibial implant. In this way, a kit can be
provided including a plurality of different posts, e.g., posts
having different sizes, being formed from different materials,
etc., and a tibial implant configured to couple to each of the
different posts. Similarly, a kit can be provided including a
plurality of different tibial implants and one post, or a plurality
of different posts, the one post or each of the plurality of posts
being configured to couple to any one of the tibial implants.
[0141] Generally, a medial tibial implant can be configured as a
substitute for a medial tibiofemoral joint. As in the embodiment
illustrated in FIGS. 2, 4, and 5, the tibial implant 28 can have a
shape substantially conforming to a shape of a medial tibial
compartment, e.g., a medial surface of a tibia 29. The tibial
implant 28 can have a size, e.g., a surface area configured to face
the medial tibial compartment, substantially similar to the medial
tibial compartment such that the tibial implant 28 can be seated on
the medial tibial compartment without extending beyond outside
edges of the tibia 29 except for a portion extending over a portion
of a lateral tibial compartment, e.g., a lateral surface of the
tibia 29. In other words, the tibial implant 28 can have a size and
shape such that the tibial implant 28 can be seated on the tibia 29
with a first portion of the tibial implant 28 being seated on or
over the tibia's medial surface and a second, substantially smaller
portion of the tibial implant being seated on or over the tibia's
lateral surface.
[0142] The tibial implant 28 can have the post 30 coupled thereto
near an edge thereof such that the post 30 can be positioned at a
region near a center of the proximal tibial bone, as also
illustrated in FIGS. 4 and 5, such that the post 30 can occupy a
lateral portion of the intercondylar region. The post 30 coupled to
the tibial implant 28 can have a variety of configurations. As in
the illustrated embodiment, the post 30 can be asymmetric in
sagittal, coronal, and transverse planes. For non-limiting example,
with reference to the embodiment of the lateral prosthesis
illustrated in FIG. 3, the tibial implant 36 of which having the
post 38 integrally formed therewith is also illustrated in FIGS.
6-8, 9, and 10, the post 38 can have an anteroposterior length a in
a range of about 5 to 35 mm, e.g., in a range of about 10 to 20 mm,
about 15 mm, etc. The prosthesis's post can have a mediolateral
width b of in a range of about 5 to 25 mm, e.g., in a range of
about 5 to 20 mm, in a range of about 5 to 15 mm, in a range of
about 8 to 15 mm, about 9 mm, etc. The post 38 can have a posterior
height c in a range of about 1 to 25 mm, e.g., in a range of about
5 to 20 mm, in a range of about 5 to 15 mm, about 8 mm, etc. The
post 38 can have an anterior height d in a range of about 3 to 25
mm, e.g., in a range of about 5 to 20 mm, in a range of about 8 to
15 mm, about 10 mm, etc. In some embodiments, the post's anterior
post height can be less than or equal to the post's posterior post
height. The post 38 can have a posterior slope in the sagittal view
such that its height anteriorly, e.g., in a range of about 8 to 15
mm, can be higher than its height posteriorly, e.g., in a range of
about 5 to 10 mm.
[0143] The location of the post 38 relative to the tibial insert 36
can vary. For non-limiting example, with reference to the
embodiment of the lateral prosthesis illustrated in FIGS. 9 and 10,
a distance e from an anterior edge of the post to an anterior edge
of the tibial base can be in a range of about 5 to 40 mm, e.g., in
a range of about 10 to 30 mm, in a range of about 15 to 25 mm,
about 22 mm, etc. A distance f from a posterior edge of the post 38
to the anterior edge of the tibial base can be in a range of about
5 to 60 mm, e.g., in a range of about 15 to 45 mm, in a range of
about 30 to 40 mm, about 37 mm, etc. A distance g from a lateral
edge of the post 38 to the lateral edge of the tibial base can be
in a range of about 10 to 50 mm, e.g., in a range of about 15 to 45
mm, in a range of about 25 to 35 mm, about 30 mm, etc. A distance h
from a medial edge of the post 38 to the lateral edge of the tibial
base can be in a range of about 15 to 60 mm, e.g., in a range of
about 25 to 50 mm, in a range of about 35 to 45 mm, about 43 mm,
etc.
[0144] In another exemplary embodiment, as illustrated in FIGS. 8A,
8B, and 8C, a tibial post 44 of a tibial insert 43 can be located
substantially anterior to the tibial center, which can avoid
potential impingement of the post 44 with a PCL ligament 46, which
is illustrated as a cylinder in FIGS. 8A and 8C. Optionally, as
illustrated in FIG. 8B, which shows a femoral component 45 of the
prosthesis 43, a femoral intercondylar notch 48 can be extended
anteriorly to enable engagement of the femoral notch 48 with the
anteriorly located tibial post 44. A dotted line in FIG. 8B
illustrates a conventional femoral intercondylar notch 48'.
[0145] In another exemplary embodiment, a tibial post can gradually
blend into a tibial insert, which can improve strength of the post.
FIG. 11 illustrates an exemplary embodiment of a prosthesis
including a gradually blending tibial post 50 adjacent a space 52
for a PCL.
[0146] In yet another exemplary embodiment, a lateral edge of a
post can be extended back to a posterior edge of a tibial insert,
which can increase tibial post strength. This embodiment can allow
gradual tibial post-femoral notch engagement from full flexion to
extension, e.g., 155.degree. to e.g., about 160.degree., and
gradual disengagement from extension to flexion, e.g., -20.degree.
to 155.degree., e.g., about 160.degree.. FIG. 12 illustrates an
exemplary embodiment of a prosthesis including a tibial insert
having such an extending post 54. In an exemplary embodiment, an
anterior width i of the post 54 can be in a range of about 3 to 25
mm, e.g., in a range of about 10 to 20 mm, about 15 mm, etc.; a
central width j of the post 54 can be in a range of about 3 to 25
mm, e.g., in a range of about 5 to 15 mm, about 8 mm, etc.; and a
length k of the post 54 can be in a range of about 5 to 35 mm,
e.g., in a range of about 15 to 30 mm, about 28 mm, etc. FIG. 12
shows a base profile 56 of the tibial insert by dotted outline,
with a space 58 for a PCL (not shown) being located adjacent the
post 54.
[0147] Referring again to the embodiment of FIG. 2, the femoral
implant 26 and the femoral notch structure 32, also shown in FIGS.
13 and 14, can also have a variety of configurations. The tibial
implant 28 can articulate against, e.g., relative to, the femoral
implant 26, and the ACL-substituting tibial post 30 can articulate
against the femoral notch structure 32. The prosthesis shown in
FIGS. 2, 13, and 14 is a medial prosthesis, but similar to that
mentioned above, a lateral prosthesis, such as an embodiment shown
in FIGS. 13A and 14A, can be configured similarly to the prosthesis
of FIGS. 2, 13. and 14. FIGS. 13A and 14A illustrate an exemplary
embodiment of a lateral knee replacement prosthesis including, a
femoral implant 33, a tibial implant 35 attached to a tibia bone
41, an ACL-substituting post 37, and a femoral notch structure
39.
[0148] Although in the illustrated embodiment of FIGS. 2, 13, and
14 the femoral notch structure 32 is integrally formed with the
femoral implant 26, in some embodiments, the femoral notch
structure and the femoral implant can be discrete elements. FIGS.
15 and 16 illustrate an exemplary embodiment of a prosthesis
including a discrete femoral notch structure 56 and a discrete
femoral implant 58. Such a discrete femoral notch structure 56 can
be independently mounted on the femoral bone. A tibial implant 60
in the embodiment of FIGS. 15 and 16 can articulate against the
femoral implant 58, and an ACL-substituting tibial post 62 coupled
to a tibia bone 64 can articulate against the femoral notch
structure 56 that is independently mounted on the femoral bone.
[0149] In addition to articulating against a tibial post, a femoral
notch structure can be configured to prevent the post from
impinging on the lateral femoral bone through the full range of
knee flexion, e.g., between extended and flexed positions of the
knee. In an exemplary embodiment, a height of the femoral notch
structure can be configured to prevent such impingement, such as by
being in a range of about 1 to 30 mm, e.g., in a range of about 2
to 15 mm, in a range of about 1 to 20 mm, in a range of about 5 to
15 mm, about 10 mm, etc. FIGS. 17 and 18 illustrate an exemplary
embodiment of a lateral prosthesis in which a height L of a femoral
notch structure 66 of a prosthesis is configured to prevent a
tibial post from impinging on the lateral femoral bone between an
extended position (FIG. 18) and a flexed position (FIG. 17). The
notch structure's height L can be in a range of about 1 to 30 mm,
e.g., in a range of about 5 to 15 mm, in is range of about 1 to 20
mm, about 10 mm, etc. In the embodiment shown in FIGS. 17 and 18,
the notch structure 66 is separate from the femoral implant such
that it is configured to be independently mounted to a femoral
bone, but as mentioned above, a notch structure can be integrally
formed with a femoral implant. Alternatively or in addition to a
height of a femoral notch structure, an edge of a tibial post can
be configured to prevent the post from impinging on the lateral
femoral bone through the full range of knee flexion. As in an
exemplary embodiment illustrated in FIGS. 19 and 20A, a lateral
edge of an ACL-substituting tibial post 68 of a tibial insert of a
lateral prosthesis can be rounded at a tip 68a thereof at a radius
r, and a height of the post 68 can be configured to avoid
impingement with lateral femoral bone 70. Being rounded at the tip
68a can allow the tibial post 68 to avoid impingement with the
lateral femoral bone 70. The radius r can be, e.g., in a range of
about 2 to 25 mm. FIGS. 19 and 20A also show the tibial insert
coupled to a femoral component 72. FIG. 20B illustrates another
embodiment of a lateral edge of an ACL-substituting tibial post 76
of a tibial insert of a lateral prosthesis that can be chamfered or
cut at an angle .gamma.. At a tip 76a thereof The angle .gamma. can
be in a range of about 5 to 70.degree.. Being chamfered or angled
at the tip 76a can allow the tibial post 76 to avoid impingement
with the lateral femoral bone. FIG. 20B also shows the tibial
insert coupled to a femoral component 74.
[0150] Alternatively or in addition to a height of a femoral notch
structure and/or an edge of a tibial post, the lateral femoral
condyle bone can be contoured during surgery to prevent the post
from impinging, on the lateral femoral bone, e.g., bone overhanging
into the femoral notch, through the full range of knee flexion. As
will be appreciated by a person skilled in the art, the lateral
femoral condyle bone can be contoured in a variety of ways, such as
by using a bone shaping tool, e.g. a burr, a reciprocating saw,
etc. In an exemplary embodiment, the bone shaping tool has a
geometry configured to match the femoral component's intercondylar
notch, which can help ensure clearance of bone in the intercondylar
region. FIGS. 20C and 20D illustrate embodiments of such bone
shaping tools 297, 298, with the bone shaping tool 299 of FIG. 20D
being shown adjacent to a femoral component 299 having an
intercondylar notch with matching geometry to the tool 299.
[0151] A prosthesis can include one or more guiding slots
configured to facilitate the bone contouring, e.g., by providing
adequate clearance for tool(s) used to contour the bone and/or by
providing adequate bony under hang (e.g., under hang in a range of
about 1 to 5 mm). The one or more guiding slots can be formed in a
femoral component of a prosthesis or in a femoral trial component
inserted into a patient prior to implantation of a femoral
component and, in an exemplary embodiment, can include at least one
guiding slot in a lateral portion of the femoral component. FIG.
20E illustrates an embodiment of a femoral trial component 292
including two guiding slots 293a, 293b in a lateral portion of the
femoral trial component 292, although any number of slots can be
provided. If multiple guiding slots are provided, the guiding slots
293a, 293b can intersect one another, which can allow a tool to
smoothly transition between slots oriented at different angles in
the femoral trial component 292. In some embodiments, a trial
tibial insert can include a tibial post having a larger size than a
tibial post coupled to a tibial insert to be implanted after the
"trial" insertion of the trial tibial insert, which can help ensure
that enough bone has been cleared so as to not impinge bone against
the tibial post coupled to the tibial insert to be implanted. FIGS.
20F and 20G illustrate an embodiment of a trial tibial post 294 of
a tibial insert that has a larger size than a tibial post 294a of a
tibial insert to be implanted. FIG. 20G shows the trial tibial post
294 adjacent a femoral component 295 and a femoral bone 296.
[0152] The femoral intercondylar notch can have a profile
substantially matching that of a tibial post. Substantially
matching the profiles of the femoral intercondylar notch and the
post can allow the post to guide femoral rotation and can maintain
continuous contact with the femoral notch even if the femoral
component is rotationally mal-aligned with respect to the tibia. As
discussed above, the medial edge of an ACL substituting post can be
contoured to avoid impingement with the PCL and can have a
generally curved or straight profile. As in an exemplary embodiment
illustrated in FIG. 21, a tibial post 78 of a lateral prosthesis
and a lateral femoral intercondylar edge 80 can have substantially
matching concentric circular profiles. In an exemplary embodiment,
a radius r5 of the circular profiles can be in a range of about 3
to 50 mm, e.g., in a range of about 5 to 30 mm, in a range of about
8 to 15 mm, about 10 mm, etc. In another exemplary embodiment
illustrated in FIGS. 21A, 21B, 21C, and 21D, a contour of a medial
edge 77a and a posterior edge 77b of a tibial post 77 can be
configured to prevent impingement of a PCL in the form of angled
cuts. In an exemplary embodiment, an angle .theta. of the posterior
edge 77b can be in a range of about 3.degree. to 80.degree., and an
angle .psi. of the medial edge 77a can be in a range of about
3.degree. to 80.degree..
[0153] FIGS. 22-27 illustrate various embodiments of prostheses
having posts and femoral intercondylar notches with substantially
matching profiles. Generally, in these embodiments, an anterior
edge of a tibial post has a convex, concave, or flat profile and
can engage with an anterior edge of a femoral notch, which also has
a convex, concave or flat profile. In an exemplary embodiment, a
radius of the convex profile or the concave profile can be in a
range of about 3 to 50 mm, e.g., in a range of about 5 to 30 mm, in
a range of about 8 to 15 mm, about 10 mm, etc. FIGS. 22 and 23
illustrate a convex femoral notch 82 of a femoral component 86
engaging with a tibial insert 88 with a tibial post 84 having a
convex profile. FIG. 24 illustrates an embodiment of a convex
femoral notch 90 engaging with a tibial post 92 having a concave
profile. FIG. 25 illustrates an embodiment of a concave femoral
notch 94 engaging with a tibial post 96 having a convex profile.
FIG. 26 illustrates an embodiment of a convex femoral notch 98
engaging with a tibial post 100 having a flat profile. FIG. 27
illustrates an embodiment of a flat femoral notch 102 engaging with
a tibial post 104 having a convex profile.
[0154] FIGS. 28-33 illustrate various embodiments of prostheses
having posts and femoral intercondylar notches with substantially
matching profiles. Generally, in these embodiments, a tibial post
occupies a lateral portion of the intercondylar region, and both a
lateral edge of a tibial post and a mating femoral notch can have a
convex, concave, or flat profile. In an exemplary embodiment, a
radius of the convex profile or the concave profile can be in a
range of about 3 to 50 mm, e.g., in a range of about 5 to 30 mm, in
a range of about 8 to 15 mm, about 10 mm, etc. FIGS. 28 and 29
illustrate an embodiment of a convex femoral notch 108 of a femoral
component 106 engaging with a tibial insert 110 with a tibial post
112 having a concave profile. FIG. 30 illustrates an embodiment of
a flat femoral notch 114 engaging with a tibial post 116 having a
flat profile. FIG. 31 illustrates an embodiment of a convex femoral
notch 118 engaging with a tibial post 120 having a convex profile.
FIG. 32 illustrates an embodiment of a convex femoral notch 122
engaging with a tibial post 124 having a flat profile. FIG. 33
illustrates an embodiment of a flat femoral notch 126 engaging with
a tibial post 128 having a convex profile.
[0155] As mentioned above, embodiments of prostheses described
herein can be configured to substitute function of an ACL at least
during early knee flexion, such as by a tibial insert of the
prosthesis including a tibial post configured to eliminate abnormal
posterior subluxation of the femur in early knee flexion.
Conventional tibial insert articular surfaces can, however, have a
relatively high anterior lip height, e.g., in a range from about 6
to 11 mm, which may hinder effectiveness of the tibial post in
substituting ACL function. Thus, tibial insert articular surfaces
of prostheses described herein can have a lower anterior lip
height, e.g., in a range of about 0 to 6 mm, e.g., less than 6 mm,
than an anterior lip height in conventional tibial inserts. FIG. 68
illustrates an embodiment of a tibial insert 224 having an anterior
lip height 224h that is less than an anterior lip height 224h' of a
conventional tibial insert 224', shown by dotted line in FIG. 68.
FIGS. 69A and 69B illustrate an embodiment of a tibial insert 226
having an anterior radius 226r, e.g., in a range of about 70 to 150
mm, that is higher than an anterior radius, e.g., in a range of
about 30 to 60 mm, of a conventional tibial insert, thereby
allowing an anterior lip height 226h of the tibial insert 226 to be
lower than an anterior lip height of the convention tibial insert.
The anterior radius 226r of the tibial insert 226 can be two or
more times larger, e.g., over four times larger, than that of a
conventional tibial insert. To allow for the lower anterior lip
height 226h, a low point 226p of the tibial insert 226 can be
located more anteriorly than a low point of a conventional tibial
insert such that a distance 226D between the low point 226p and a
lateral edge of the tibial insert 226 can be greater than a
distance between a low point and a lateral edge of the conventional
tibial insert. FIG. 70 illustrates an embodiment of a tibial insert
228 having a lower anterior lip height than a conventional tibial
insert by having an intermediate radius 228r, located between an
anterior radius 228r' and a posterior radius 228r'' of the tibial
insert 228, that can be substantially larger than the anterior
radius 228f'. The intermediate radius 228 can be, e.g., in a range
of about 70 to 300 mm, and the anterior radius 228r' can be, e.g.,
in a range of about 30 to 60 mm. The intermediate radius 228 of the
tibial insert 228 can therefore be two or more times larger, e.g.,
at about five times larger, than that of a conventional tibial
insert. In some embodiments, the intermediate radius 228r can be
substantially flat.
[0156] Medial and lateral anterior lip heights of a tibial insert
can have different heights to allow for ACL substitution at least
during early knee flexion. In a normal knee, the ACL attaches to
the lateral femoral condyle and pulls the ACL more anteriorly on
the tibia than the medial femoral condyle. Thus, generally, an
anterior medial lip height of a tibial insert can be greater than
an anterior lateral lip height of the tibial insert. Medial and
lateral tibial insert profiles can be different from one another to
reflect this normal ACL function. FIG. 71 illustrates an embodiment
of a tibial insert 230 having a convex lateral profile 230L and a
concave medial profile 230M. These profile geometries can result in
an anterior medial lip height that is greater than an anterior
lateral lip height by an amount 230D, e.g., greater by at least 1
mm, e.g., in a range of about 1 to 10 mm. These profile geometries
can allow the lateral femoral condyle to be located more anteriorly
than the medial femoral condyle.
[0157] In some embodiments, an anterior edge of a tibial insert can
extend at an angle relative to a base of the tibial insert, which
can allow for ACL substitution at least during early knee flexion
by increasing a tibiofemoral contact area during knee extension.
The anterior location of a femoral component on a tibia due to
engagement of the femoral component against the tibial insert's
post can pull the femur forward on the tibia. Thus, in extension
and particularly in hyperextenstion, the femoral component contacts
the tibial insert at its anterior edge. The angled anterior edge
can therefore increase tibiofemoral contact. FIG. 72 illustrates an
embodiment of a tibial insert 232 having an anterior edge 232A
extending at a non-zero angle a relative to a base 232B of the
tibial insert 232 such that the anterior edge 232A extends
anteriorly at the non-zero angle .alpha.. The angle .alpha. can be
up to about 30.degree., e.g., about 15.degree., up to about
5.degree., in a range of about 5.degree. to 10.degree., in a range
of about 10.degree. to 20.degree., in a range of about 20.degree.
to 30.degree., etc.
[0158] Instead of reducing an anterior lip height of a tibial
insert as compared to a conventional tibial insert, a distal
femoral condyle radius of a femoral implant can be reduced as
compared to a conventional tibial insert, thereby allowing a
prosthesis including the femoral implant to substitute function of
an ACL at least during early knee flexion. FIG. 73 illustrates an
embodiment of a tibial insert 234 having a reduced distal femoral
condyle radius 234r. The distal femoral condyle radius 234r is
medial in the illustrated example, but similar to that mentioned
above regarding medial/lateral prostheses, a distal femoral condyle
radius of a tibial insert can be lateral, thereby allowing an
anterior lip height 234h of the tibial insert 234 to be greater
than or equal to an anterior lip height of the convention tibial
insert, and still allow for ACL substitution function without
impediment. To allow for the greater anterior lip height 234h, a
low point 234p of the tibial insert 234 can be located more
posterior than a low point of a conventional tibial insert such
that a distance 234D between the low point 234p and a lateral edge
of the tibial insert 234 can be greater than a distance between a
low point and a lateral edge of the conventional tibial insert.
[0159] As mentioned above, prostheses described herein can be
configured for use in total knee replacement surgical procedures.
Generally, total knee replacement prostheses can be configured
similarly to the partial knee replacement prostheses discussed
above and variously illustrated in FIGS. 2-33 and 68-73 except that
the total knee replacement prostheses can be configured to
resurface both a medial tibial compartment and a lateral tibial
compartment. In other words, a total knee replacement prosthesis
can be configured to be seated on the medial and lateral tibial
compartment to provide total knee replacement and an ACL
substitution. Like-named elements of partial knee replacement
prostheses and total knee replacement prostheses discussed herein
can generally be similarly configured.
[0160] FIG. 34 illustrates an exemplary embodiment of a knee
replacement prosthesis configured to provide substitution of an ACL
in total knee replacement surgery. As in the illustrated
embodiment, the prosthesis can include a femoral implant 130, a
tibial implant 132, and an ACL-substituting post 134. The tibial
implant 132 can include a space 136 adjacent the post 134
configured to accommodate a PCL (not shown). A prosthesis
configured for total knee replacement surgery can also include a
femoral component 140 including a femoral notch structure 138, such
as in an exemplary embodiment illustrated in FIGS. 35 and 36. FIGS.
35 and 36 show the femoral component 140 coupled to a tibial insert
142 including a tibial post 144, and FIG. 35 shows a posterior view
of the femoral component 140 coupled to a femoral bone 146 and the
prosthesis seating a PCL 148, which is illustrated as a
cylinder.
[0161] FIG. 37 illustrates a posterior view of the prosthesis of
FIG. 34 in use with the patient's PCL ligament 131 being
represented as a cylinder joining the tibial insertion of the
ligament 131 to its insertion on the medial femoral condyle within
the intercondylar region. FIG. 38 shows the prosthesis and PCL
ligament 131 of FIG. 37 with the PCL ligament 131 in different
positions corresponding to different knee flexion angles between
about 0.degree. to 70.degree.. FIGS. 39-43 illustrate the tibial
implant 132 of the prosthesis of FIG. 34 and variously include
reference characters a1, b1, c1, d1, e1, f1, g1, and h1
respectively corresponding to length, width, posterior height,
anterior height, and distances of the post 134 similar to that
discussed above with reference to FIGS. 6-10. As shown, for
example, in FIGS. 42 and 43, the tibial implant 132 in a total knee
replacement prosthesis can be generally kidney-shaped to
substantially match the tibial surfaces to which it can be
affixed.
[0162] FIGS. 44 and 45 illustrate exemplary embodiments of total
knee replacement prostheses that are respectively similar to the
embodiments of FIGS. 11 and 12 discussed above. FIG. 44 illustrates
an exemplary embodiment of a prosthesis including a gradually
blending tibial post 150 adjacent a space 152 for a PCL. FIG. 45
illustrates an exemplary embodiment of a prosthesis including a
tibial insert having an extending post 154, the post 154 having an
anterior width i1, a central width j1, and a length k1. FIG. 45
shows a base profile 156 of the tibial insert by dotted outline,
with a space 158 for a PCL (not shown) being located adjacent the
post 154.
[0163] As discussed above, a notch structure and/or a post can be
configured to prevent the post from impinging on the lateral
femoral bone through the full range of knee flexion. FIG. 46
illustrates an exemplary embodiment of a prosthesis having a tibial
insert 162 having a post 160 with a height configured to avoid
impingement with the lateral femoral condyle. The prosthesis can
also include a femoral component 164 adjacent a femoral bone 166.
The patient's PCL ligament 168 is represented as a cylinder. FIGS.
47 and 48, similar to FIGS. 19 and 20A, illustrate an exemplary
embodiment of a prosthesis having a lateral edge of an
ACL-substituting tibial post 170 of a lateral prosthesis rounded on
top. FIGS. 47 and 48 also illustrate a femoral component 172 mated
to a tibial insert 174 that includes the post 170. FIGS. 49 and 50,
similar to FIGS. 17 and 18, illustrate an exemplary embodiment of a
prosthesis in which a height L1 of the prosthesis's notch structure
176 can be configured to prevent a post 178 of a tibial implant 180
from impinging on the lateral femoral bone between an extended
position (FIG. 49) and a flexed position (FIG. 50). The height L1
of the notch structure 176 can be in a range of about 1 to 20 mm,
in a range of about 5 to 15 mm, about 10 mm, etc.
[0164] Similar to that discussed above, a femoral intercondylar
notch of a total knee replacement prosthesis can have a profile
substantially matching that of the prosthesis's post. FIG. 21 also
illustrates an exemplary embodiment of a tibial post of a total
knee replacement prosthesis having a concentric circular profile
substantially matching concentric circular profile of anterior and
lateral surfaces of the femoral intercondylar notch structure.
FIGS. 23-27 discussed above also illustrate exemplary embodiments
of prostheses having posts and femoral intercondylar notches with
substantially matching profile, where the embodiment of FIG. 23
shows a sagittal cross section of an embodiment of a total knee
replacement prosthesis 182 illustrated in FIG. 51 that includes a
femoral component 184 and a tibial insert 186. The prosthesis 182
of FIG. 51 includes a convex tibial post 188 and a convex femoral
intercondylar notch 190. Similar to FIGS. 28-33 discussed above,
respectively, FIGS. 52-57 illustrate various embodiments of total
knee replacement prostheses having posts and femoral intercondylar
notches with substantially matching profiles. FIG. 52 illustrates
one embodiment of a total knee replacement prosthesis having a
tibial insert 192 with a concave tibial post 194 and a femoral
component 196 with a convex femoral intercondylar notch 198. FIG.
53 is a coronal plane cross-sectional view of the prosthesis of
FIG. 52 attached to a tibia. FIG. 54 illustrates one embodiment of
a total knee replacement prosthesis attached to a tibia and having
a flat tibial post 200 and a flat femoral intercondylar notch 202.
FIG. 55 illustrates one embodiment of a total knee replacement
prosthesis attached to a tibia and having a convex tibial post 204
and a convex femoral intercondylar notch 206. FIG. 56 illustrates
one embodiment of a total knee replacement prosthesis attached to a
tibia and having a flat tibial post 208 and a convex femoral
intercondylar notch 210. FIG. 57 illustrates one embodiment of a
total knee replacement prosthesis attached to a tibia and having a
convex tibial post 212 and a flat femoral intercondylar notch
214.
[0165] In addition to a prosthesis for total knee replacement being
configured for ACL substitution, the prosthesis can be configured
for PCL substitution. Providing a substitute for a PCL with a knee
replacement prosthesis can help reduce a number of surgical
procedures needed to repair the knee and/or can help the knee's
functionality approach 100% after surgery. Generally, PCL and ACL
substituting total knee replacement prostheses can be configured
similarly to ACL-only substituting knee replacement prostheses
discussed herein except that the PCL and ACL substituting total
knee replacement prostheses can be configured for ACL substitution
via engagement of an anterior surface of the prosthesis's tibial
post with the anterior femoral intercondylar notch. In contrast, a
conventional prosthesis substitutes PCL function via the engagement
of a posterior femoral cam and a posterior surface of a tibial
post. FIGS. 74A and 74B illustrate an embodiment of an ACL and PCL
substituting total knee replacement prosthesis including a femoral
component 236 including a PCL substituting cam 236p and an ACL
substituting cam 236a, and a tibial insert including a tibial post
238. Because of the absence of the PCL, an intercondylar notch of
the femoral component 236 can have a relatively large surface area
configured to mate with the tibial post's geometry, as shown in
FIGS. 74A and 74B, thereby allowing contact stresses at the mating
interface to be reduced. In some embodiments, such as in an
embodiment illustrated in FIG. 75, this relatively large surface
area can be achieved by a thickness 240t, e.g., a thickness in a
range of about 4 to 10 mm (e.g., greater than 5 mm), of a femoral
notch 240 of a femoral component being greater than a thickness,
e.g., in a range of about 2 to 5 mm, of a femoral notch in a
conventional femoral component, and by a radius 240r, e.g., in a
range of about 5 to 30 mm, of the femoral notch 240 being greater
than a radius, e.g., in a range of about 2 to 5 mm, of a femoral
notch in a conventional femoral component. In other embodiments,
such as in an embodiment illustrated in FIG. 76A, this relatively
large surface area can be achieved without increasing thickness
242t but by a radius 242r, e.g., in a range of about 5 to 30 mm, of
a femoral notch 242 being greater than a radius, e.g., in a range
of about 2 to 5 mm, of a femoral notch in a conventional femoral
component.
[0166] Tibial posts of prostheses configured to substitute ACL and
PCL function can have a variety of profiles. As in one embodiment
shown in FIG. 77, a tibial post 244 can have a convex profile in a
top-down view, which can be configured to engage a rounded geometry
of a femoral notch 246 of a femoral component. The convex profile
of the post 244 can have a radius 244r, e.g., in a range of about 5
to 60 mm. A posterior surface 244p of the post 244 can have a flat
profile configured to engage with a flat posterior femoral cam. In
another embodiment, shown in FIG. 78, anterior and posterior
surfaces of a tibial post 248 can have a convex profile configured
to engage with a concave profile of a femoral intercondylar notch
250 and a posterior femoral cam 252. The convex profile of the post
248 can have a radius 248R, e.g., in a range of about 5 to 60 mm.
In yet another embodiment, shown in FIG. 79, a tibial post 250 can
have an angled posterior surface 250p configured to engage a
posterior femoral cam 252 and configured to allow asymmetric
posterior motions of the medial and lateral condyles. In a sagittal
view, anterior and posterior surfaces of an ACL and PCL
substituting post can be angled. The angles of the surfaces can
both be anterior, both be posterior, or one of each. The angle
degree of the surfaces can vary, such as being a positive angle up
to about 15.degree.. FIG. 80A illustrates one embodiment of a post
254 that is posteriorly sloped relative to a base 254b of a tibial
insert including the post 254, which includes posteriorly sloped
posterior and anterior surfaces 254a, 254p. FIG. 80B illustrates
one embodiment of a post 256 that is anteriorly and posteriorly
sloped relative to a base 256b of a tibial insert including the
post 256, which includes a posteriorly sloped posterior surface
256p and an anteriorly sloped anterior surface 256a.
[0167] In any of the prosthesis embodiments disclosed herein, a
tibial insert can be in a fixed, non-variable position relative to
a tibial base such that a post coupled to the tibial insert,
whether the post is integral with the tibial insert or is a
discrete element from the tibial insert, can be in a fixed,
non-variable position relative to the tibial base. Alternatively,
in any of the prosthesis embodiments disclosed herein, particularly
in total knee replacement prostheses, the a tibial insert can be in
non-fixed, non-variable positions relative to a tibial baseplate.
In other words, a prosthesis can be a mobile bearing implant in
which the tibial insert is not in a fixed, non-variable position
relative to the prosthesis's tibial base.
[0168] As in an embodiment illustrated in FIG. 81A, 81B, and 81D, a
mobile bearing tibial insert 258 of a total knee replacement
prosthesis can include a base, e.g., a baseplate 260, a medial
tibial insert 262 fixedly coupled to the baseplate 260, and a
lateral tibial insert 264 movably coupled to the baseplate 260 such
that the lateral tibial insert 264 can move relative to the
baseplate 260 and to the medial tibial insert 262. A tibial post
266 can be coupled, either integrally or as a discrete element, to
the medial tibial insert 262. The lateral tibial insert 264 can
therefore be movable relative to the post 266. The lateral tibial
insert 264 can be movably coupled to the baseplate 260 in a variety
of ways, such as by a rail/track system. The baseplate 260 includes
an anterior-posterior rail 268, as shown in FIGS. 81A and 81D, and
the lateral tibial insert 264 includes a rail 270, but the
baseplate 260 could include a rail with the lateral tibial insert
including a track. The rail/track in the illustrated embodiment has
a T-shaped cross-section, but a rail/track system can have any
cross-sectional shape. The lateral tibial insert 264 can be
configured to be substantially conforming to a mating lateral
femoral condyle, as shown in FIG. 81B. FIG. 81B also shows movable
motion of the lateral tibial insert 264 relative to the baseplate
260 and the post 266 with the lateral tibial insert 264 in solid
line in a first position and in dotted line in a second, different
position. Only two different positions of the lateral tibial insert
264 is shown in FIG. 81B, but the lateral tibial insert 264 can be
movable between any number of positions relative to the baseplate
260 and the post 266. A surface 260s of the baseplate 260, e.g., a
top surface, to which the inserts 262, 264 can be coupled can have
a convex profile in a sagittal view, as shown in FIG. 81B. The
baseplate's convex profile can have a radius 260r, e.g., in a range
of about 20 to 200 mm, in a range of about 60 to 200 mm, in a range
of about 20 to 100 mm, etc. Alternatively, as shown in FIG. 81C, a
surface 260s' of a baseplate 260' to which medial and lateral
tibial inserts can be coupled can be substantially flat in a
sagittal view. A tibial baseplate 275 including a substantially
flat baseplate surface can, as shown in one embodiment in FIG. 81E,
be movably coupled to a tibial insert by including opposed side
rails 272 that define a channel 274 in which the tibial insert 276
can move. Similarly, a tibial baseplate 275a including a convex
baseplate surface 275b can, as shown in one embodiment in FIG. 81F,
be movably coupled to a tibial insert by including one side rail
272a that defines an interior guide surface along which a tibial
insert 276a can move.
[0169] Although a tibial post can be coupled to a tibial insert
coupled to a baseplate in a mobile beating implant as discussed
above, in another embodiment, a tibial post can be coupled to a
baseplate, either integrally or as a separate element, while medial
and/or lateral tibial inserts coupled to the baseplate can be
movably coupled to the baseplate. In an exemplary embodiment, both
the medial and lateral tibial inserts can be movably coupled to the
baseplate. FIG. 82A illustrates one embodiment of a tibial
baseplate 278 having a medial tibial insert 279a movably coupled
thereto, a lateral tibial insert 279b movably coupled thereto, and
a tibial post 280 non-movably coupled thereto either integrally or
as a separate element. The medial and lateral tibial inserts 279a,
279b can therefore each be movable relative to the post 280 and
relative to each other. The medial and lateral tibial inserts 279a,
279b can each be coupled to the baseplate 278 in any way, same or
different from one another, such as by being movable within
respective tracks 281a, 281b formed in the baseplate 278.
[0170] In another embodiment, similar to that discussed above
regarding a prosthesis including a tibial post coupled to a tibial
insert coupled to a baseplate in a mobile bearing implant, a
movable medial or lateral tibial insert can be movably coupled to a
baseplate having a substantially flat top surface including opposed
side rails defining a channel in which a tibial insert can move.
The side rails for a lateral tibial insert can be a farther
distance apart from one another than side rails for a medial tibial
insert such that the medial tibial insert can be configured to
undergo less anteroposterior translation compared to the lateral
tibial insert. This movement can allow normal kinematics
characterized by greater anteroposterior tibiofemoral motion in the
lateral compartment of the knee. FIG. 82B illustrates an embodiment
of a baseplate 281 including a substantially flat baseplate surface
to which a medial tibial insert 282a and a lateral tibial insert
282b can be coupled. The surface can include anterior-poster
opposed side rails 283a spaced a distance 284a apart from one
another between which the medial tibial insert 282a can move and
anterior-poster opposed side rails 283b spaced a farther distance
284b apart from one another between which the lateral tibial insert
282b. The side rails 283a, 283b can therefore be configured as
anterior-posterior stops, e.g., one 283a located posteriorly and
the other 283a located anteriorly and one 283b located posteriorly
and the other 283b located anteriorly, so as to allow their
associated tibial insert to move within a define anterior-posterior
area.
[0171] In another embodiment, a baseplate can include a protruding
convex member on a top surface thereof configured to allow a tibial
insert coupled to the baseplate to pivot thereabout. In one
embodiment illustrated in FIG. 82C, a baseplate 285 can include a
protruding convex member 286 about which a tibial insert 287, e.g.,
a medial tibial insert, can pivot. The protruding convex member 286
can have a relatively small radius 286r, e.g., in a range of about
3 to 30 mm. By having a relatively small radius 286r, the
protruding convex member 286 can allow the tibial insert 287 to
have relatively limited anteroposterior motion. FIG. 82C shows the
tibial insert 287 in a solid line in a first position at one end of
the insert's range of pivotal motion and in a dotted line in a
second position at the other end of the insert's range of pivotal
motion. FIG. 82D illustrates a baseplate 288 including a convex
surface 289 to which a tibial insert 290, e.g., a lateral tibial
insert, can mate and be movable relative thereto. The convex
surface 289 can have a relatively large radius 289r, e.g., in a
range of about 50 to 200 mm, which can allow for greater
anterior-posterior motion to occur than with a smaller radius. FIG.
82D shows the tibial insert 290 in a solid line in a first position
at one end of the insert's range of pivotal motion and in a dotted
line in a second position at the other end of the insert's range of
pivotal motion. A baseplate including the relatively small radius
protruding convex member 286 of FIG. 82C for a medial tibial insert
and the relatively large radius convex surface 289 of FIG. 82D for
a lateral tibial insert can allow for greater mobility of medial
relative to a lateral side of the tibia, which can allow for
natural medial pivot kinetics.
EXAMPLES
[0172] The performance of an ACL-substituted CR prosthesis
configured for total knee replacement surgery was compared with
that of a conventional CR implant. Five different activities of a
knee including the prosthesis were simulated, namely lunge, deep
knee bend, chair rise/sit, stair ascent, and walking. These
simulations were carried out using a Virtual Knee Simulator,
available from LifeModeler.RTM. Inc. of San Clemente, Calif., and
the motion of the medial and lateral flexion facet centers (FFC)
were measured during each activity. In all simulations the ACL
ligament was absent, while the PCL ligament was present. During all
simulated activities, the ACL-substituted prosthesis showed
kinematics close to that of healthy knees. In contrast, the
conventional CR prosthesis showed abnormal posterior location of
the femur at full extension and abnormal anterior sliding during
early to mid-flexion for all the simulated activities.
[0173] FIGS. 58-67 illustrate the prosthesis along with various
graphical results of the comparisons. Generally, FIGS. 58-65
illustrate results of simulations for the lunge, deep knee bend,
and chair rise/sit activities with reference to in vivo knee motion
data for healthy subjects variously extracted from Johal et al.,
"Tibio-Femoral Movement In The Living Knee: A Study Of Weight
Bearing And Non-Weight Bearing Knee," J Biomech. 2005 February,
38(2):269-76; Komistek et al., "In Vivo Fluoroscopic Analysis Of
The Normal Human Knee," Clin Orthop Relat Res. 2003 May,
(410):69-81; and Moro-oka, et al., "Dynamic Activity Dependence Of
In Vivo Normal Knee Kinematics," J Orthop Res. 2008 April,
26(4);428-34. Generally, FIGS. 66 and 67 illustrate graphs showing
results of simulated walking with reference to in vivo knee motion
data for patients who received bi-unicondylar implants that
preserve both the ACL and PCL ligaments extracted from Banks et
al., "Comparing In Vivo Kinematics Of Unicondylar And
Bi-Unicondylar Knee Replacements," Knee Surg Sports Traumatol
Arthrosc. 2005 October, 13(7):551-6.
[0174] FIGS. 58 and 59 illustrate graphical results of motion
during, simulated lunge activity, one cycle of flexion from
0.degree. to 120.degree. and one cycle of extension from
120.degree. to 0.degree., with reference to healthy subject data
from Johal et al., referenced above. FIG. 58 shows the motion of
the medial FFC 300 as a function of knee flexion angle during a
lunge activity. The medial FFC in the conventional CR implant was
shifted posteriorly at full extension and showed abnormal anterior
sliding in early to mid-flexion, e.g., from 0.degree. to
50.degree.. In contrast, the ACL-substituted CR prosthesis showed
more normal medial FFC motion, with minimal anterior-posterior
translation until 90.degree. flexion followed by posterior
translation at higher flexion angles. FIG. 59 shows the motion of
the lateral FFC 302 as a function of knee flexion angle during a
simulated lunge activity. The lateral FFC in the conventional CR
implant was again shifted posteriorly at full extension and showed
abnormal anterior sliding during early to mid-flexion. In contrast,
the ACL-substituted CR prosthesis showed kinematics very close to
the in vivo kinematics of healthy knees.
[0175] FIGS. 60 and 61 illustrate graphical results of motion
during simulated deep knee bend activity, one cycle of flexion from
0.degree. to 155.degree. and one cycle of extension from
155.degree. to 0.degree., with reference to healthy subject data
from Johal et al., referenced above. FIG. 60 shows the motion of
the medial FFC 304 as a function of knee flexion angle during a
deep knee bending activity. The medial FFC in the conventional CR
implant was shifted posteriorly at full extension and showed
paradoxical anterior sliding in a mid-flexion range, e.g., from
about 0.degree. to 55.degree.. In contrast, the ACL-substituted CR
prosthesis showed more normal medial FFC motion, with minimal
anterior-posterior motion until 85.degree. flexion followed by
posterior translation at higher flexion angles. FIG. 61 shows the
motion of the lateral FFC 306 as a function of knee flexion angle
during a simulated deep knee bending activity. The lateral FFC in
the conventional CR implant was again dislocated posteriorly at
full extension and showed paradoxical anterior sliding in the
mid-flexion range. On the other hand, the ACL-substituted CR
prosthesis showed kinematics closely mimicking the in vivo
kinematics of healthy knees.
[0176] FIGS. 62 and 63 illustrate graphical results of motion
during simulated rising from and sitting into a chair, one full
cycle from 10.degree. to 105.degree. flexion and from 10.degree. to
105.degree. flexion, with reference to healthy subject data from
Komistek et al., referenced above. Similar to the lunge and deep
knee bending activities, the medial FFC of the conventional CR
prosthesis again showed abnormal posterior location and anterior
sliding during a simulated chair rise/sit activity, as shown in
FIG. 62. The motion of the medial FFC 308 for the ACL-substituted
CR prosthesis was much more consistent with the in vivo data. Like
the medial FFC, the lateral FFC for the conventional CR prosthesis
showed abnormal posterior location at full extension followed by
anterior sliding, as shown in FIG. 63. In contrast, the lateral FFC
310 of the ACL-substituted prosthesis showed posterior rollback of
the lateral FFC consistent with in vivo data.
[0177] FIGS. 64 and 65 illustrate graphical results of motion
during simulated stair ascent, one full cycle from 0.degree. to
90.degree. flexion and from 90.degree. to 0.degree. flexion, with
reference to healthy subject data from Moro-oka et al., referenced
above. FIG. 64 shows that during the simulated stair ascent, the
medial FFC of the conventional CR prosthesis showed abnormal
posterior location at full extension, followed by anterior sliding.
The motion of the medial FFC 312 motion for the ACL-substituted CR
prosthesis was much more stable, although it did not show the
posterior rollback seen in the in vivo data. Like the medial FFC,
the lateral FFC for the conventional CR prosthesis also showed
abnormal posterior location at full extension followed by anterior
sliding, as shown in FIG. 65. In contrast, the lateral FFC 314 of
the ACL-substituted prosthesis showed posterior rollback consistent
with in vivo data.
[0178] FIGS. 66 and 67 illustrate graphical results of motion
during simulated walking, one full gait cycle going from 0.degree.
to 65.degree. flexion and from 65.degree. to 0.degree. flexion,
with reference to data from Banks et al., referenced above. FIG. 66
shows the motion of the medial FFC as a function of knee flexion
angle during simulated walking. The medial FFC in the conventional
CR implant was located posteriorly at full extension and showed
significant anterior sliding during flexion. In contrast, the
ACL-substituted CR prosthesis showed more stable medial FFC 316
motion, similar to that seen in vivo for patients with ACL and PCL
preserving implants. FIG. 67 shows the motion of the lateral
flexion facet center as a function of knee flexion angle during
simulated walking. The lateral FFC in the conventional CR implant
was again located posteriorly at full extension and showed abnormal
anterior sliding with flexion. In contrast, the ACL-substituted CR
prosthesis showed lateral FFC 318 motion similar to that seen in
vivo for patients with ACL and PCL preserving implants.
[0179] The devices disclosed herein can be designed to be disposed
of after a single use, or they can be designed to be used multiple
times. In either case, however, the device can be reconditioned for
reuse after at least one use. Reconditioning can include any
combination of the steps of disassembly of the device, followed by
cleaning or replacement of particular pieces, and subsequent
reassembly. In particular, the device can be disassembled, and any
number of the particular pieces or parts of the device can be
selectively replaced or removed in any combination. Upon cleaning
and/or replacement of particular parts, the device can be
reassembled for subsequent use either at a reconditioning facility,
or by a surgical team immediately prior to a surgical procedure.
Those skilled in the art will appreciate that reconditioning of a
device can utilize a variety of techniques for disassembly,
cleaning/replacement, and reassembly. Use of such techniques, and
the resulting reconditioned device, are all within the scope of the
present application.
[0180] One skilled in the art will appreciate further features and
advantages of the invention based on the above-described
embodiments. Accordingly, the invention is not to be limited by
what has been particularly shown and described, except as indicated
by the appended claims. All publications and references cited
herein are expressly incorporated herein by reference in their
entirety.
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